Assessing The Position And Angulation Of Single Implants Restored In

The Predoctoral Dentistry Program

By

Waad M. Kheder

A thesis submitted in conformity with the requirements

for the degree of MSc Prosthodontics

Department of Prosthodontics

University of Toronto

© Copyright by Waad Kheder 2014

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Assessing The Position And Angulation Of Single Implants Restored In The Predoctoral

Dentistry Program

Waad M. Kheder

Masters of Science

Graduate Prosthodontics

University of Toronto

2014

Abstract

Objective: to assess if single implants restored in the undergraduate clinic at the Faculty of

Dentistry, University of Toronto, are placed in a compromised position and angulation relative to

the adjacent natural teeth. Materials and Methods: The study sample consists of 108 patients

treated with single implants placed in the Implants Placement Unit and restored by predoctoral

students at the Faculty of Dentistry, University of Toronto. Assessing the angulation and 3D

position of implant relative to adjacent teeth were conducted by using the measurement tool in

the 3D scanner. Results: The highest percentage of the non-ideal implant position was for

mesiodistal implant position and the lowest percentage was for the non-ideal buccolingual

implant angulation. Conclusion: The placement of the implant in a non-ideal position/angulation

may be due to: Gingival biotype, buccal cortical plate concavity, selected implant diameter and

Implant site relation to vital anatomical structures and roots of adjacent teeth.

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Table of Contents

1- Introduction …………………………….………………………………………………...… 1

2- Aim of Study……………………………………………………………………………..… 13

3- Materials and Methods……………….……………………...…………………………….. 14

3.1- Materials ………………………………………………………….……….…....…….. 14

3.1.1- Patients inclusion criteria based on undergraduate implantology protocol…….14

3.1.2- Stone Models …………………………………………………..……..…….….14

3.1.3- 3Shape D180 Scanner …………………………………………..…………..…16

3.1.4- 3Shape Dental Manager Software ……………….…………………………...17

3.2- Methods ………………………………………………………………………..…..….. 19

3.2.1- Stone model scanning ……………………………………….…………............19

3.2.2- Implant position assessment technique ………………………….………..........20

3.2.2.1- Mesiodistal implants position assessment ………….………………...20

3.2.2.2- Buccolingual implants position assessment ……………….….………25

3.2.2.3- Apicocoronal implants position assessment …………….……………28

3.2.3- Implant angulation assessment technique.…………………...……….…….…. 31

3.2.3.1- Mesiodistal implant angulation assessment ……..………………….....32

3.2.3.2- Buccolingual implant angulation assessment …..…………..........……35

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3.2.3.2.1- Posterior implant .….……………………………...….…....35

3.2.3.2.2- Anterior implant ………………………….....……………..38

3.3- Statistical Analysis …………………………………………………………………………40

4- Results ………………………………………………………………………..…….………...41

4.1. Mesiodistal Implant position (mesial side) ………………………………………….…41

4.2. Mesiodistal Implant position (distal side) ………………………………………….…..41

4.3. Mesiodistal Implant angulation (mesial side).…………………………………..……...43

4.4. Mesiodistal Implant angulation (distal side)……………………………………....……44

4.5. Buccolingual implant position (buccal side) ………….……………….………………45

4.6. Buccolingual implant position (lingual side)…….………………………………….…46

4.7. Buccolingual implant angulation (buccal side)……………………..……….…...….....47

4.8. Buccolingual implant angulation (lingual side) ……………………..………………....48

4.9. Apicocoronal implant position ………………………………………..……...…….…..49

5- Discussion ……………………………………………………………….………...………….52

5.1- Selected implant diameter……………………………….…...........................................52

5.2- Gingival biotype …………………………………….......................................................55

5. 3- Buccal cortical plate concavity ………………………………………………….….... 56

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5.4- Implant site relation to vital anatomical structures and the roots of adjacent teeth

……………………………………………………………………………………..….…57

6- Conclusion………………………………………………………………………………….…58

References……………………………………………….……………………….……………...59

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List of Figures

Fig. 1: Ideal implant position in the buccolingualdimension.........................................................7

Fig. 2: Ideal implant position in the mesiodistal dimension...........................................................8

Fig. 3: Ideal implant position in the apicocoronal dimension........................................................9

Fig. 4: Defective tooth adjacent to the single implant .................................................................15

Fig. 5: Gingival recession of the teeth adjacent to the single implant .........................................16

Fig. 6a & b: 3Shape D810 dental laboratory scanner (3Shape A/S, Copenhagen, Denmark)…. 16

Fig. 7: 3Shape D810 dental scanner: setting up the scan field .....................................................17

Fig. 8a&b: 3Shape dental manager software measurement tools ................................................18

Fig. 9: A 2D cross section graph image ........................................................................................21

Fig.10a&b: Mesiodistal distance (distal), implant replacing tooth #11 ........................................21

Fig.11a&b: Mesiodistal distance (mesial), implant replacing tooth #11 …...……….................. 22

Fig.12a&b: Mesiodistal distance (distal), implant replacing tooth #36 ……................................23

Fig.13a&b: Mesiodistal distance (mesial), implant replacing tooth #36 ......................................24

Fig. 14: Buccal sides of teeth adjacent to the implant as reference points, tooth#11....................26

Fig. 15: Buccal sides of teeth adjacent to the implant as reference points, tooth #36...................26

Fig. 16: Lingual sides of teeth adjacent to the implant as reference points, tooth #36..................27

Fig. 17: Lingual sides of teeth adjacent to the implant as reference points, tooth #11..................27

Fig. 18: Looking at a non-right angle to the occlusal surface of the implant #36.........................27

Fig. 19: Lingual sides of teeth adjacent to the implant as reference points, tooth #36….. …….. 28

Fig. 20a&b: Apicocoronal implant position in relation to adjacent teeth (teeth #11&36)…...29-30

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Fig.21: a.Correct angulation to assess the apicocoronal implant position, b. Incorrect

angulation.......................................................................................................................................30

Fig. 22a, b & c: Mesiodistal angulation of implant replacing tooth #36…………………..…….34

Fig. 23a & b: Mesiodistal angulation of implant replacing tooth #11….……………….….……35

Fig. 24a & b: Buccolingual implant angulation-buccal height of contour as a reference point…36

Fig 25a & b: Buccolingual implant angulation-lingual height of contour as a reference point….37

Fig. 26a&b: Buccolingual implant angulation-buccal height of contour as a reference point.38-39

Fig. 27a&b: Buccolingual implant angulation-implant adjacent teeth cingula as a reference.39-40

Fig. 28: Mesiodistal implant position (mesial side) …………….….…………………….……...42

Fig. 29: Mesiodistal implant position (distal side)…………..…………………………………..43

Fig. 30: Mesiodistal implant position histogram…………………………………………….…..44

Fig. 31: Mesiodistal implant angulation (mesial side) …………..………………………………45

Fig. 32: Mesiodistal implant angulation (distal side)…………………………………...……..…46

Fig. 33: Buccolingual implant position (buccal side) …………………..……………………….46

Fig. 34: Buccolingual implant position (lingual side) ………..…………………………………46

Fig. 35: Buccolingual implant position histogram ……………….……………………………...47

Fig. 36: Buccolingual implant angulation (buccal side)……………...………………………….47

Fig. 37: Buccolingual implant angulation (lingual side)……...…………………………………48

Fig. 38: Buccolingual implant angulation histogram……………………………………………49

Fig. 39: Apicocoronal implant position………………………...………………………………..49

Fig. 40: Apicocoronal implant position histogram …...…………………….………………..….50

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List of Tables

Table 1: summary of the implants in a non-ideal angulation and 3D position …………….51

List of Appendices

Appendix A: Ethics Approval Form .......................................................................................64

Appendix B: Statistical Analysis Tables.……………….……………....…….………...........65

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1- Introduction

The placement of dental implants in a functionally and esthetically correct position and

angulation is still considered a challenge in spite of major advances in surgical techniques and

devices. Therefore, it is important to place the dental implants in a correct angulation and

position in relation to each other, adjacent teeth, and to the underlying bone, since alveolar bone

loss following tooth extraction often makes ideal implant placement difficult (Talwar et al.,

2012). Furthermore, non-axial loading of implant-supported prostheses may occur due to

incorrectly positioned and non-parallel dental implants which may cause improper occlusal load

distribution, overloading of the implant and ultimately failure of osseointegration (Saab et al.,

2007; Talwar et al., 2012). In addition, parallelism between dental implants supporting

overdentures is important to achieve complete seating of retentive elements, predictable

attachment retention, prevention of premature wear of the involved components, and provision of

axial loading (Gulizio et al., 2005).

One of the important factors leading to dental implant failure after fabrication of

prostheses is overloading; therefore, successful implant placement requires accurate positioning

and angulation to achieve a predictable esthetic result and resistance to heavy occlusal forces

(Payer et al., 2008; Al-Harbi & Sun, 2009; Talwar et al., 2012). According to an early report, 20

percent of implants which were located too far palataly had bone loss greater than 2 mm

(Cummings & Arbree, 1995).

The use of dental implant therapy in the treatment of dentate patients has become a well-

established clinical procedure due to its predictability and success in practice (Afsharzand et al.,

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2005; Petropoulos et al., 2008). The successful application of implants to restore edentulous sites

has captured the interest of the public (Wilcox et al., 2010). In our information technology era,

patients have become more educated and value how dental implants may improve the esthetics,

function, and oral health, and prevent the adverse psychosocial impact of the loss of all or some

of their natural teeth (Gulizio et al., 2005).

In order to meet the increase in patient expectation about dental implant treatments,

predoctoral dental students must be familiar with the indication of implants and able to offer

treatment at the proper level (Lee et al., 2011). Thus, it seems universally accepted to include

straight forward cases for implant therapy in the dental predoctoral curriculum in most dental

schools worldwide since implant-supported single-tooth replacements showed few biological and

technical complications as well as high survival rates (Bonde et al., 2010). The introduction of

implant dentistry education greatly varies from one school to another. For example, at the

University of Illinois-Chicago College of Dentistry, responsibilities of predoctoral dental

students as part of a predoctoral implant program include: a complete dental examination,

consideration of the patient’s medical history, identification of diagnostic criteria for implant

placement, diagnostic wax-ups, fabrication of radiographic and surgical templates, and assisting

in surgery (Lee et al., 2011).

However, the majority of schools allow predoctoral students to practice only the

restorative part of implant treatment; some schools include an additional didactic part and

laboratory instruction course in the curriculum (Kronstrom et al., 2008). In the United States,

36% of dental schools allow students to restore implants, 42% offer laboratory instruction in

implant dentistry, and a small number of dental schools allow students to place the dental

implant (Huebner, 2002). In contrast, Bavitz reported in 1989 that two percent of the

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undergraduate dental students participated in the surgical stage of implants therapy and 11%

provided restorative care for implant patients (Maalhagh-Fard et al., 2002).

Some studies found that exposing students to dental implant therapy at the predoctoral

level is directly related to an increased use of implants later in general practice (Maalhagh-Fard

et al., 2002). A survey conducted at the School of Dentistry/ University of Detroit Mercy found a

strong correlation between student participation in a predoctoral implantology elective program

and the use of implant restorations in their practices after graduation (Kido et al., 2009). Lee et

al. (2011) found that a predoctoral implant program can provide predictable patient-centered

therapy with few complications. The difficulty of incorporating dental implants in the

predoctoral curriculum may be due to several logistical barriers including lack of curriculum

time (53%), limited financial resources (28%), limited assisting staff (51%) and limited number

of patients who fulfill the educational criteria in relation to a large number of students

(Weintraub et al., 1995; Ghani & Moeen, 2011).

In spite of the continuous growth in the number of implant training programs, there are

still only a few studies available about the survival of implants placed and restored in these

programs (Petropoulos et al., 2008; Kido et al., 2009). From an educational point of view, it is

important to evaluate patients’ opinions and the clinical outcome of the treatment executed by

predoctoral dental students (Kronstrom et al., 2008). An evaluation of the clinical outcome of

implants placed in university training programs would be beneficial to identify and manage the

application of didactic and hands-on components in the predoctoral dental implant curriculum

(Petropoulos et al., 2008; Kido et al., 2009). In the literature, there are many studies about the

role of students in predoctoral implant dentistry programs in dental schools around the world;

none of those studies evaluated the single implant position restored in those undergraduate dental

4

programs. Most of those studies discussed the variety in duties of undergraduate students

according to their dental school implant curriculum, and the outcome or complication of implant

supported restoration. Thus, it is important to study the causes of these complications which may

be due to incorrect implant position and angulation.

Implant osseointegration is not the only factor which affects the success of implant-

supported restorations; the position and angulation of the implant may affect the success,

esthetics and function of the restoration. Precise assessment of the surgical site is required for

implant placement and restoratively driven treatment planning (Park et al., 2009).

Dental implant osseointegration is a predictable treatment modality; nevertheless, restorative

problems due to non-optimal implant placement may happen. Adverse outcomes relating to an

implant’s position and angulation may affect the longevity and success of a prosthetic

rehabilitation. These consequences arise when implants are not optimally placed in one or more

geometric planes (e.g., mesiodistally, buccolingually and apicocoronally). As a result, after

placing the implant and before selecting a restorative plan, the clinician should decide whether

there is a need to deal with issues relating to implant placing position.

The surgical guide is an effective method to ensure the communication, which is required

with regards to the implant position occur between the restorative dentist and the surgeon. Using

a surgical guide helps to provide guidance for implant placement in the ideal mesiodistal position

if the guide is fabricated according to correct artificial teeth setting in the diagnostic model.

Failure to use a surgical guide is considered one of the etiological factors related to prosthetic

complications after implant insertion. Therefore, before implant placement and surgical guide

fabrication, it is necessary to accomplish the planning phase, using appropriate radiographic

5

examination combined with study casts. All these can provide comprehensive information

regarding the three dimensional anatomy of an implant site (Froum, 2010).

A 3D scanner may be used to assess the angulation and three dimensional position of the

implant by scanning a stone model with implant replica and healing abutment.This scanner may

also be used to scan dental impression, inlays and bridge preparations, stone models and implant

retained restorations. The three dimension scanner consists of one or more cameras, a light

source, and a motion system supporting several axes to position the scanned object towards the

camera(s) and the light source. The camera(s) obtains images of the well-defined lines which are

projected by the light source onto the surface of the object. Based on the known distance and

angle between the light source and camera (together called the scan head), the 3D position(s)

where the projected light is reflected may be calculated using trigonometry. This principle of

measurement which is done with one camera is known as “triangulation”; and by using two

cameras the scan speed, accuracy and scan coverage will improve (Hollenbeck et al., 2012).

There is no common standard for validating and measuring the accuracy of 3D dental

scanners. In general, scanner manufacturers do not even disclose how they measure their

accuracy claims. Therefore, claimed accuracies – usually in the area of 20 microns – cannot be

compared or even confirmed. Scanner software algorithms cannot compensate for temperature

effects as the scanner hardware itself contains fasteners, weldings, varying loads, glued sections,

etc., and as a result it is prone to highly complex contraction and expansion. Accordingly, it is

important to re-calibrate the scanner when it is moved or when the lab’s temperature changes

(Hollenbeck et al., 2012).

The 3D scanner may capture the details of the dental model with high accuracy within 5

minutes.To ensure the maximum exposure of the object (model) to the scanner’s cameras and

6

light, the model is usually placed on a 360 degree rotation plate and is moved along a linear axis

(translation) and a secondary rotation axis (tilt) (Hollenbeck et al., 2012).

Ideal three dimensional positioning of the planned implants is a key to ideal treatment outcome

for optimal support and stability of the peri-implant soft and hard tissues regardless of the

implant system used. Implant 3D position will influence the relationship between the proposed

restoration and the implant, and the final hard and soft tissue response (Buser et al., 2004).

Preoperative planning and measurements are essential to accomplish a correct implant placement

to facilitate future implant supported prosthesis. Placing the implant in an incorrect position and

angulation in relation to adjacent teeth is an embarrassing, frustrating, and avoidable

complication. Measuring height and width of the ridge helps to verify if implants are indicated in

the first place. Implant position should be in line with some of the landmarks for adjacent teeth

and centered in relation to the opposing occlusion to avoid crossbites or overload on the

prosthesis (Misch & Wang 2008).

Proper buccolingual implant position results in a proper emergence profile, simplifies the

restorative procedure, and facilitates oral hygiene. At least 1 mm buccal wall thickness must be

maintained to prevent gingival recession and improve esthetics. In general, placing the implant

too far facially or lingually can create a number of complications at the prosthetic phase of

treatment, because soft-tissue topography follows the underlying osseous contour dehiscence of

the buccal cortical plate and gingival recession may occur as a result of placing the implant too

far buccally. This placement makes the restoration of the implant more complicated. In contrast,

placing the implant too far palataly usually requires a ridge-lap restoration in an attempt to

restore the crown to its correct position, which is both unesthetic and unhygienic (Al-Sabbagh,

2006; Froum, 2010).

7

The implant should be placed in such a way which makes the crown emerges from the

soft tissue scaffold and creates the illusion of a natural tooth. To accomplish this, the implant

centerline must regularly be located at or near the center of the replaced tooth; in some situations

this requires placing the implant in a more palatal position (e.g., implant site with a thin gingival

biotype). On the other hand, it is preferable to place the implant slightly labially to harmonize

with the occlusion of the opposing teeth, mainly in cases involving excessive vertical overlap

(Al-Sabbagh, 2006). Accordingly, evaluation of gingival biotype and type of occlusion at the

area of implant placement is necessary before planning the position of implant placement.

Another way to place the implant in an ideal buccolingual position is by depending on the

implant platform position; the margin of implant shoulder should be at the ideal point of

emergence. The palatal danger zone is located about 1.5-2 mm from the imaginary line drawn

between the emergence of the implant adjacent teeth and/or planned restoration. The labial

danger zone is located anywhere facially to that imaginary line (Fig. 1) (Buser et al., 2004).

Fig. 1: Ideal implant position in the buccolingual dimension (Buser et al., 2004).

8

Careful measuring of the mesiodistal space for the edentulous space (implant site) is

necessary for the selection of proper implant size and correct implant space planning.

Interproximal bone loss with subsequent loss of papillary height may occur as a result of placing

the implant too close to the adjacent tooth. According to Tarnow et al. (2000) and Esposito et al.

(1993), the distance of the implant to the adjacent tooth affects the crestal bone loss around the

implant. Usually 1.5-2 mm is the minimum distance required distance between the implant and

the neighbouring tooth.

The mesiodistal dimension of the implant site should be the same as that of the

neighbouring tooth (centrals) or the contralateral one (e.g., premolars, molars). It is preferable to

correct deficiencies or excesses in these dimensions by the use of enameloplasty, restorative

materials, or orthodontics before placing the implant. For implant placement in the mesiodistal

dimensions, the danger zones are located close to adjacent root surfaces and this zone is about

1.5 - 2 mm wide. The implant shoulder should avoid the danger zone and be positioned within

the comfort zone (Fig. 2) (Tarnow et al., 2000; Buser et al., 2004).

Fig. 2: Ideal implant position in the mesiodistal dimension (Buser et al., 2004).

9

It is easy to conceptualize the prevention of buccolingually or mesiodistally implant

malposition, but might be difficult to put into practice for a variety of reasons (e.g., anatomic

limitations). The clinician must visualize the osteotomy entry point or use the surgical guide to

put the implant in a correct angulation and position in relation to adjacent teeth. Malpositioned

implants are less amenable to modification than other implant placement issues (e.g., angulation

issues). In the esthetic zone, malposed implants can be problematic and may have to be removed

and new implants placed (Froum, 2010).

The apicocoronal implant position is related to the implant shoulder position. The implant

should be placed about 2-3 mm apical to the mid-facial gingival margin of the planned

restoration.The surgical guide may be used to achieve this relation with the planned restoration

(Buser et al., 2004). The apical incorrect position is usually anywhere 3 mm or more apical to the

proposed gingival margin of the restored tooth. On the other hand, the coronal incorrect position

is invaded once the implant shoulder is placed less than 2 mm coronal to the proposed gingival

margin and this may lead to poor emergence profile and a visible metal margin (Fig. 3). For

patients with no gingival recession, the implant shoulder is placed 1 mm apical to the CEJ of the

contralateral tooth (Buser et al., 2004; Al-Sabbagh, 2006).

Fig. 3: Ideal implant position in the apicocoronal dimension (Buser et al., 2004).

10

Implant angulation is determined by the trajectory of the drill while it proceeds into the

bone (Froum, 2010). Taking into consideration the implant’s angulation, it is necessary to

establish a balance between anatomic and prosthetic concerns. For instance, the platform of the

implant may be in a correct position, but the implant may require angulation to prevent surgical

fenestration of lingual cortical plate in the mandible or the labial bone in case of a concavity in

the anterior maxilla (Greenstein et al., 2008). Therefore, the implant might be placed in an ideal

position, but its trajectory might be misaligned; this may cause a severe misangulation (> 25

degrees) or a minor misangulation (0-15 degrees). It is easy to manage misangulation up to 15

degrees; most of the available prefabricated abutments are in 0–15 degree configurations. To

correct more severe implant angulation problems, components can be custom cast (e.g., 25˚,

35°).

The amount of existing running room is the major concern related to correction of

buccolingual angulation issues. Angulated components, which are usually used with incorrectly

angulated implant, require extra crevicular space (running room) to correct the angulation issue

before the abutment continues coronally to hold the implant supported crown. When there is not

enough running room (the implant is not placed apically enough), this will creating an esthetic

problem as the metal is likely to be visible. In addition, there will be possibility of fracture of the

coronal aspect of an implant, screw fracture, or abutment screw loosening as a result of high

stresses placed on the implant–abutment interface. These complications will be exacerbated in

the posterior area due to the greater masticatory forces. From a functional perspective, if severe

implant angulation cannot be avoided, additional implants can be placed to provide

supplementary support and avoid the previously mentioned complications (Lundgren & Laurell,

1984; Pjetursson et al., 2004; Greenstein et al., 2008).

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The anatomy at the proposed implantation site may cause minor mesiodistal angulation

issues. For example, avoiding penetration of the maxillary sinus and a vital structure such as the

mental foramen or the root of an adjacent tooth may dictate angulation of the implant. The non-

ideal mesiodistal angulation of the implant becomes evident when the coronal aspect of a transfer

coping makes contact with an adjacent tooth or transfer coping. In the esthetic zone, mesiodistal

angulation issues combined with inadequate running room may cause a metal abutment to be

exposed, which may be unesthetic. Prostheses supported by misangulated implants are subject to

extra forces, which may contribute to premature mechanical failures. Angulated components

may be used to provide parallelism between non-ideal angulated implants. Correcting an

angulation issue with a 25 degree abutment can shift a prosthesis 2-2.5 mm, and a 15 degree

angled abutment can shift a restoration about 1-1.5 mm at the occlusal side.

The angulation of the implant affects its esthetic and home care.The implant must be

placed to make the implant abutment resemble the natural tooth preparation. Poor implant

angulation (too much towards the palatal or the buccal) in case of screw retained prostheses can

alter screw placement and compromise the home care and esthetics. If the teeth adjacent to the

implant site are in reasonably good alignment, it is acceptable to place the implant in angulation

that mimics the angulation of adjacent teeth (Al-Sabbagh, 2006).

Our study will be the first one to evaluate, in an undergraduate dental program, the

bucco-lingual and mesiodistal position and angulation, and apicocoronal position of single

anterior and/or posterior implants in relation to natural adjacent teeth. Taking into consideration

the comfort zones in the three dimensional position will result in an implant located in an ideal

position in relation to adjacent teeth, soft tissue, and underlying bone.

12

The University of Toronto has an existing dental implant curriculum at the undergraduate

level which would benefit from feedback and quality control to evaluate the need for any

modification. This might improve the quality of single implant placement and restorations

performed by undergraduate students. As discussed earlier, it is necessary to place implants in

optimal position and angulation to achieve an acceptable functional and esthetic outcome.

Therefore, this study was proposed to assess single implant position and angulation, on stone

models, restored in the undergraduate clinic at the University of Toronto, Faculty of Dentistry.

13

2- Aim of Study

The aim of this study is to assess if the single implants restored in the undergraduate clinic at

the Faculty of Dentistry, University of Toronto, are placed in a compromised position and

angulation relative to the adjacent natural teeth.

14

3- Materials and Methods

3.1. Materials

3.1.1. Patients inclusion criteria based on undergraduate implantology protocol

1- A patient in need of single implant-supported crowns.

2- Teeth bounded implant site.

3- A patient with good bone quality (free of infection and no tooth chips remained after tooth

extraction).

4- A patient with good bone quantity (no need for bone graft).

5- A patient with standard dental radiographs (periapical radiograph and a panoramic

radiograph) to assist in determining the amount and quality of the bone available at the

proposed implant sites as well as the location of large nerves and blood vessels in relation to

implant site.

3.1.2. Stone Models

The study commenced after obtaining approval for scientific merit from the Research

Committee at the Faculty of Dentistry, University of Toronto (protocol reference # 28973). The

study sample consisted of all patients (128 patients) treated with single implants placed in the

Implants Placement Unit (IPU) and restored by predoctoral students at the Faculty of Dentistry,

University of Toronto, since incorporation of this treatment in the predoctoral curriculum. The

128 maxillary and mandibular stone models (available in the IPU office) for patients with

anterior and/or posterior single implants were collected; only 108 models fitted the inclusion

criteria for this study, and the 108 models included in the final appraisal. Any model with broken

15

stone teeth adjacent to the implant or with defective stone at the area of the single implant were

excluded from the study (Fig. 4); in addition, stone models for patients with gingival recession of

the teeth adjacent to the single implant were excluded from the study (Fig. 5).

On the stone model, the location of the original implant was represented by an implant

replica which was connected to a 10 mm high healing abutment. The healing abutment helped in

the process of stone model scanning and measurements by using the measurement tool available

in the 3Shape Dental Manager software of the scanner, to determine single implant mesiodistal

position in relation to adjacent teeth. The healing abutments has the same diameter of the implant

as this helped to simulate the implant diameter at the level of adjacent teeth cementoenamel

junction where the distance between the implant and the adjacent tooth was measured. The

maximum height for healing abutment available in the school is 6 mm and this height would not

reach the cementoenamel junction level of the implant adjacent teeth for the purpose of

apicocoronal implant position assessment (especially for an implant placed too deep).

Accordingly, a 10 mm height healing abutment fabricated by Nobel Biocare for narrow, regular

and wide platform implants was used to help in apicocoronal implant position assessment.

Fig. 4: Defective tooth adjacent to the single implant

16

Fig. 5: Gingival recession of the teeth adjacent to the single implant

3.1.3. 3Shape D180 Scanner

The 3Shape scanner provides three dimensional scanning of the stone models, as well as

metal implant bars and full-arch bridges. This technology includes 5.0 MP cameras, adaptive

impression scanning, and texture-capture capabilities (3D Scanner manual) (Fig. 6a & b).

a b

Fig. 6a & b: 3Shape D810 dental laboratory scanner (3Shape A/S, Copenhagen, Denmark)

17

The scanner captures the reflected lights from the scanned object with its two 5-

megapixel adjustable cameras. It employs a 3-axis rotation, translation and tilting mechanism to

move the object when scanning (Fig. 7). The system provides a high level of accuracy with a

maximum permissible error of 16 μm over 60 mm scan length and a maximum permissible

probing error of 2 μm. The scanned surfaces are required to be covered with a masking opaque

powder in order to eliminate reflections on the metal of healing abutment and implant replica

surfaces during the scanning stage. After scanning, the powder can be easily removed with a

small brush under running water.

Fig. 7: 3Shape D810 dental scanner: setting up the scan field

3.1.4. 3Shape Dental Manager Software

The scanner uses 3Shape Dental Manager Software to measure different characteristics

and dimensions of objects and compares them to the standard prosthesis specifications; 3Shape

Dental Manager has an extensive library of measurements grid, point dragging, material shaders,

2D cross section, 3D and 2D measurement tools, the software allows for a point-to-point distance

18

three-dimensional measurement for any given region of interest (3D Scanner manual) (Fig. 8a &

b).

a

b

Fig. 8a & b: 3Shape dental manager software measurement tools

19

3.2. Methods

After identifying patients with single implant retained restorations placed by predoctoral

students, their electronic health records were obtained from Axium at the Faculty of Dentistry,

University of Toronto, to obtain the following necessary information about the cases which were

included in the study:

1- Type of teeth adjacent to single implant site: the selected study samples should have natural

teeth (not restored with crowns) adjacent to the single implant. This is to avoid changes in the

adjacent teeth landmarks which were used as reference points to assess the position and

angulation of the single implant in relation to adjacent teeth.

2- Implant diameter: This helped in the selection of healing abutments that were attached to

implant replica during scanning of stone models; the diameter of the healing abutment should be

the same as that for the implant.

3.2.1. Stone model scanning

A high resolution stationary scanner, a 3Shape D810 dental laboratory scanner (3Shape

A/S, Copenhagen, Denmark), was used for scanning the stone models to identify the three

dimensional (buccolingual, apicocoronal and mesiodistal) position of the single implant in

relation to adjacent natural teeth. A 10 mm high healing abutment was used to help in identifying

the mesiodistal position of single implant in relation to the adjacent teeth. A 3 mm diameter

attachment screw was attached to the implant replica on the stone model to help in the scanning

of the model and assessing the mesiodistal and buccolingual implant angulation in relation to

implant adjacent teeth.

20

3.2.2. Implant position assessment technique

Implant position is the mesiodistal, buccolingual and apicocoronal locations that the

implant center occupies within the bone, that is to say, the center of the entry point of the implant

osteotomy. All measurements for assessing the mesiodistal, buccolingual and apicocoronal

implant position for anterior and posterior single implant in relation to mesial and distal surfaces

of the adjacent teeth were conducted by using the measurement tool available in the 3Shape

Dental Manager Software of the 3D scanner. The measurements depended on the lines which

were drawn in relation to the implant and the anatomical landmarks of adjacent teeth. During

stone model scanning, a 10 mm high healing abutment was attached to the implant replica,

representing the occlusal extension of the implant to help in assessing single implant position.

3.2.2.1. Mesiodistal implants position assessment

A line was drawn on the scanned stone model to pass through the healing abutment and

the mesial and/or distal adjacent tooth depending on the curvature of the dental arch and the

buccolingual implant position. A 2D cross section graphic screen (Fig. 9) was displayed during

the process of drawing this line. The distance from the lateral surface of the healing abutment to

the proximal surface of the adjacent tooth was measured on the 2D cross section graphic image

by drawing a line from the lateral surface of the healing abutment to the mesial or distal surface

of the adjacent tooth at the cemento-enamel junction level (Fig. 10a & b, 11a & b, 12a & b, 13a

& b).

21

Fig. 9: A 2D cross section graph image

a

b

Fig. 10a & b: Mesiodistal distance (Distal), implant replacing tooth # 11

22

a

b

Fig. 11a & b: Mesiodistal distance (Mesial), implant replacing tooth # 11

23

a

b

Fig. 12a & b: Mesiodistal distance (Distal), implant replacing tooth # 36

24

a

b

Fig. 13a & b: Mesiodistal distance (Mesial), implant replacing tooth # 36

To obtain a precise measurement of the distance from implant lateral surface to the

mesial or distal surface of the adjacent tooth, the line which is drawn by the 2D cross section tool

in the 3Shape Dental Manager Software should pass through the healing abutment and the mesial

and/or distal adjacent tooth. When this line passes through the healing abutment and the adjacent

teeth, there will be (on the graphic screen) clear and intact lateral surfaces for the healing

abutment and the adjacent teeth, which in turn will help to obtain a precise mesiodistal distance

measurement to assess the mesiodistal implant position.

25

Accordingly, for anterior and posterior implant, there will be an ideal and non-ideal

mesiodistal implant position in relation to the adjacent tooth. The implant will be in an ideal

position when there is at least 1.5mm distance from the lateral surface of the implant to the

proximal surface of the adjacent tooth at the gingival margin level. The non-ideal implant

position is when there is less than 1.5 mm distance from the lateral surface of the implant to the

mesial or distal surface of the adjacent tooth at the gingival margin level (Tarnow et al., 2000;

Buser et al., 2004; Froum, 2010).

The distance from the implant to the mesial or distal adjacent tooth depends on the

mesiodistal distance of the implant site and the diameter of the selected implant. After reviewing

the available mesiodistal distance for each case in the study sample, the data showed that the

majority of the cases have a mesiodistal implant site more than the mesiodistal distance that is

required to replace the missing tooth. Accordingly, the difference in the distance from the

implant to the mesial and distal adjacent tooth was considered as a guide to assess the ideal/non-

ideal mesiodistal implant position.

When the distance of the implant from the mesial adjacent tooth minus its distance from

the distal adjacent tooth was 0-1 mm, the implant was in an ideal mesiodistal position as it was

positioned almost midway of the available mesiodistal distance which was, as mentioned before,

more than the required mesiodistal distance for the majority of the cases in the study sample.

3.2.2.2. Buccolingual implant position assessment

Two lines were drawn to be used as reference points to determine the buccolingual

position of the single implant in relation to mesial and distal adjacent teeth. The first line is

represented by the facial curvature of the arch at the level of the gingival margin (Fig.14 &15).

26

The second line connects the lingual sides of the adjacent teeth at the level of the gingival margin

(Fig. 16 &17). These lines were drawn while looking at a right angle to the occlusal surface of

the implant; if it was not at a right angle, this would affect the accuracy of the implant position

assessment technique (Fig. 18).

Fig. 14: Buccal sides of teeth adjacent to the implant as reference points, tooth # 11

Fig. 15: Buccal sides of teeth adjacent to the implant as reference points, tooth # 36

27

Fig. 16: Lingual sides of teeth adjacent to the implant as reference points, tooth # 36

Fig. 17: Lingual sides of teeth adjacent to the implant as reference points, tooth # 11

Fig. 18: Looking at anon-right angle to the occlusal surface of the implant # 36

28

To place the implant in an ideal buccolingual position in relation to the adjacent teeth, the

implant should be located between the two reference lines representing the buccal and lingual

sides of the adjacent teeth at the gingival margin level, and the distance from the facial surface of

implant platform to the buccal reference line is 1.5 mm (Buser et al., 2004; Froum 2010). The

first non-ideal buccolingual implant position is when its platform is located less than 1.5 mm

from the buccal reference line. The second non-ideal buccolingual implant position is when its

platform is located partially or completely lingual to the lingual reference line.

For posterior teeth, when the implant was located too far lingually, the lingual reference line was

represented by a line that was in contact with the comparable adjacent tooth (at the level of

gingival margin) and parallel to the 2D section line which was in contact with the buccal surface

of the implant adjacent teeth (Fig. 19).

Fig. 19: Lingual sides of teeth adjacent to the implant as reference points, tooth # 36

3.2.2.3. Apicocoronal implant position assessment

The vertical distance from the platform of the implant to the line connecting the mesial

and distal adjacent teeth at the mid-facial gingival margin level represents the apicocoronal

position of the implant in relation to the adjacent teeth (Fig. 20 a & b). The line which measures

29

the distance from the implant platform to the line connecting implant adjacent teeth should be

drawn parallel to the long axis of the implant when the occlusal surfaces of the adjacent teeth are

parallel to the floor (Shillingburg, 2012). In addition, the implant replica should appear as a clear

and intact line parallel to the floor while looking at it from the facial surface (Fig. 21 a), and not

as surface area (Fig. 21 b).

Fig. 20 a: Apicocoronal implant position in relation to adjacent teeth (teeth #36).

30

Fig. 20 b: Apicocoronal implant position in relation to adjacent teeth (teeth #11).

a b Fig.

21: a. Correct angulation to assess the apicocoronal implant position, b. Incorrect angulation

On the stone model, it is unreliable to use a cementoenamel junction of the implant

adjacent teeth, as a reference point to assess the apicocoronal position of the single implant as the

cementoenamel junction cannot be determined precisely on the stone models. According to the

exclusion criteria in this study, samples with gingival recession of the implant adjacent teeth

were excluded, as the gingival margin level of the implant adjacent teeth was used as reference

points.

In addition, the wax-up and surgical stent, to identify the mid-facial margin of the

planned restoration to be used as a reference point,was not available. Therefore, the gingival

31

margin level of the implant adjacent teeth was used as a reference point because the midfacial

margin level of the planned restoration followed the midfacial margin level of the implant

adjacent teeth. Accordingly, the apicocoronal implant position is ideal when the distance from

the implant platform to the line connecting the adjacent teeth is 2-3 mm (Buser et al., 2004;

Froum, 2010), and it is non-ideal when the distance is less than 2 mm (more coronal implant

position), or more than 3 mm (more apical implant position).

3.2.3. Implant angulation assessment technique

Implants should be placed in angulation to make the implant abutment resemble the

preparation of a natural tooth. Poor implant angulation (too much toward the palatal or the buccal

side) can alter screw placement, and often compromise esthetics and impact home care. If the

teeth adjacent to the implant site are in reasonably good alignment, it is acceptable to place the

implant in such a way as to mimic the angulation of adjacent teeth.When the implant is placed in

an ideal angulation parallel to the adjacent tooth, the access hole for the abutment screw ideally

is supposed to be located at the mid-point of the mesiodistal and buccolingual distance of the

implant supported crown.

There was no “standard reference point” to be used as a reference for the measurement of

the angle between the implant and the adjacent tooth, and no “specific or standard angle” that

may be consider as an ideal angle (ideal angulation) between the implant and the adjacent tooth.

In addition, there was no information in patient’s record to confirm if the surgeon placed the

implant in relation to the angulation of the mesial or distal adjacent tooth. So it was not reliable

or practical to assess the angulation of the implant based on measuring the angle between the

implant and the adjacent tooth. Accordingly, the assessment of implant angulation in relation to

32

the mesial and/ or distal adjacent tooth was based on the distance from the mesial or distal

adjacent tooth, at the occlusal or incisal level, to the lateral surface of the attachment screw that

is representing the abutment screw of the implant supported restoration. The same principle used

to assess the buccolingual implant angulation in relation to the adjacent teeth.

This technique of measurement helped to determine the percentage of the implants in a

non-ideal mesiodistal and/or buccolingual angulation when there is less than 1 mm (minimum

thickness of the porcelain for implant supported restoration) between the implant and the mesial

and/or distal adjacent tooth at the level of the incisal edge for the anterior teeth and the marginal

ridge for the posterior teeth.

All measurements for mesiodistal and buccolingual implant angulation, for anterior and

posterior single implants in relation to the adjacent teeth, were conducted by using the

measurement tool available in the 3Shape Dental Manager Software of the 3D scanner. The

abutment screw that connects the implant to the crown restoration was represented on the stone

model by a 3 mm diameter attachment screw which was attached to the implant replica, and this

helped in assessing the mesiodistal and buccolingual single implant angulation in relation to the

adjacent teeth.

3.2.3.1. Mesiodistal implant angulation assessment

Lines were drawn to connect the lateral surface of the attachment screw and the mesial or

distal surfaces of the adjacent teeth at the marginal ridge level of the posterior teeth (Fig. 22a, b

& c) and at the incisal edge level of the anterior teeth (Fig. 23a &b). The ideal or non-ideal

mesiodistal implant angulation was assessed on the graphic images according to the distance

from the lateral surface of attachment screw to the mesial or distal surfaces of the adjacent teeth.

33

Accordingly, there was an ideal mesiodistal implant angulation when the distance was 1 mm or

more from the lateral surface of the attachment screw to the proximal surface of the adjacent

tooth, and non-ideal mesiodistal implant angulation when the distance was less than 1 mm

(Shillingburg, 2012).

To obtain a precise measurement of the distance from the lateral surface of the

attachment screw to the proximal surface of the adjacent tooth, the measurement line should pass

through the attachment screw and the teeth adjacent to the implant. When this line passes

through the attachment screw and adjacent teeth, there will be a clear and intact lateral surface

for the attachment screw and adjacent teeth on the graphic image, which in turn will help to

obtain a precise mesiodistal distance measurements to assess the mesiodistal implant angulation.

34

a

b

c

Fig. 22a, b & c: Mesiodistal angulation of implant replacing tooth # 36.

35

a

b

Fig. 23a & b: Mesiodistal angulation of implant replacing tooth # 11

3.2.3.2. Buccolingual implant angulation assessment

3.2.3.2.1. Posterior implant

The buccolingual angulation of the single posterior implant was assessed depending on

the relation of the attachment screw to the buccal reference line which connects the buccal height

of contour of the teeth adjacent to the implant (Fig. 24a & b). One mm is the minimum distance

required between the facial surface of the attachment screw and the line connecting the buccal

36

height of the contour of the implant adjacent teeth; this line was drawn while looking at a right

angle to the occlusal surface of the implant (Shillingburg, 2012).

a

b

Fig. 24a & b: Buccolingual implant angulation-buccal height of contour as a reference point

(tooth # 36)

When the implant was located too far lingually, the angulation of the implant was

assessed depending on the distance from the lingual surface of the attachment screw to the

lingual reference line that was in contact with the comparable adjacent tooth at the lingual height

of contour level, and parallel to the “graphic image line” that was in contact with the lingual

surface of the attachment screw (e.g., if the implant replaced the mandibular first molar tooth, the

comparable adjacent tooth would be the mandibular adjacent second molar) (Fig. 25a & b).

37

a

b

Fig 25a & b: Buccolingual implant angulation-lingual height of contour as a reference point

(tooth # 36)

Accordingly, the ideal buccolingual implant angulation was when the distance 1 mm or

more from the facial surface of the attachment screw to the buccal reference line or when it was

1 mm or more from the lingual surface of the attachment screw to the lingual reference line. The

non-ideal buccolingual implant angulation was when the previously mentioned distances were

less than 1 mm.

38

3.2.3.2.2. Anterior implant

A line was drawn to connect the buccal height of contour of the implant adjacent teeth

(Fig. 26a & b). This line was used as a reference point to determine the buccolingual implant

angulation in relation to the adjacent teeth, and was drawn while looking at a right angle to the

occlusal surface of the implant.

The minimum distance required between the facial surface of the attachment screw and

the line connecting the buccal height of contour of the implant adjacent teeth was 1mm as a

clearance for the porcelain of the implant supported crown (Shillingburg, 2012). Accordingly,

the buccolingual implant angulation was considered ideal when the distance from the facial

surface of the attachment screw to the line connecting the buccal height of contour of the implant

adjacent teeth was 1 mm or more and non-ideal buccolingual implant angulation when that

distance was less than 1 mm.

Fig. 26a: Buccolingual implant angulation-buccal height of contour as a reference point (tooth #

11)

39

b

Fig. 26b: Buccolingual implant angulation-buccal height of contour as a reference point (tooth #

11)

When the implant was located too far lingually in relation to the adjacent anterior teeth,

the implant was in an ideal buccolingual angulation when the distance from the lingual surface of

the attachment screw to the reference line that was in contact with the cingula of the implant

adjacent teeth was 1 mm or more, and non ideal when the distance was less than 1 mm (Fig. 27a

&b).

Fig. 27 a: Buccolingual implant angulation-implant adjacent teeth cingula as a reference point

(tooth # 11)

40

Fig. 27b: Buccolingual implant angulation-implant adjacent teeth cingula as a reference point

(tooth # 11)

3.3. Statistical Analyses

Statistical analysis was performed by using SPSS software to conduct a descriptive analysis

of the data collected after stone models scanning. SPSS software was used to find Median, Mean,

Standard deviation and Range for the following:

1- Mesiodistal implants position/angulation from the mesial and distal sides separately.

2- Buccolingual implants position/angulation from the buccal and lingual sides separately.

3- Apicocoronal implants position.

41

4- Results

4.1. Mesiodistal implant position (mesial side)

In 108 implants the values of mesiodistal implant position from the mesial side ranged

from 1.2 to 5.3. The mean of mesiodistal implant position from the mesial side was 2.8

(SD=0.93). The median was 2.69 (Fig. 28).

Fig. 28: Mesiodistal implant position (mesial side)

4.2. Mesiodistal implant position (distal side)

In 108 implants the values of mesiodistal implant position from the distal side ranged

from 0.64 to 4.55. The mean of mesiodistal implant position from the distal side was 2.5

(SD=0.79). The median was 2.36 (Fig. 29).

42

Fig. 29: Mesiodistal implant position (distal side)

The histogram (Fig. 30) shows the percentages of implants placed in a non-ideal

mesiodistal position; 21.28 % of the implants included in this study were placed in a non-ideal

position based on assessing the mesiodistal implant position in relation to the mesial and then the

distal adjacent tooth separately, 9.25 % were placed in a non-ideal position from the mesial

adjacent tooth only, and 12.03 % were placed in a non-ideal position from the distal adjacent

tooth only. In addition, 67.59 % was the percentage of the implants placed in a non-ideal

mesiodistal position based on assessing the position of the implant in relation to both the mesial

and distal adjacent teeth at the same time.

43

Fig. 30: Mesiodistal implant position histogram

4.3. Mesiodistal implant angulation (mesial side)

In 55 implants the values of mesiodistal implant angulation from the mesial side ranged

from 1.26 to 4.6. The mean of mesiodistal implant angulation from the mesial side was 2.7

(SD=0.84). The median was 2.72 (Fig. 31).

44

Fig. 31: Mesiodistal implant angulation (mesial side)

4.4. Mesiodistal implant angulation (distal side)

In 53 implants the values of mesiodistal implant angulation from the distal side ranged

from 1.4 to 4.6. The mean of mesiodistal implant angulation from the distal side was 2.7

(SD=0.75). The median was 2.66. All implants were placed in an ideal mesiodistal angulation

(Fig. 32).

45

Fig. 32: Mesiodistal implant angulation (distal side)

4.5. Buccolingual implant position (buccal side)

In 95 implants the values of buccolingual implant position from the buccal side ranged

from -.93 to 5.01. The mean of buccolingual implant position from the buccal side was 2.0

(SD=1.03). The median was 1.97 (Fig. 33).

Fig. 33: Buccolingual implant position (buccal side)

46

4.6. Buccolingual implant position (lingual side)

In 13 implants the values of buccolingual implant position from the lingual side ranged

from 0.3 to 1.93. The mean of buccolingual implant positionfrom the lingual side was 0.97

(SD=0.51). The median was 1.18 (Fig. 34).

Fig. 34: Buccolingual implant position (lingual side)

The histogram (Fig. 35) shows the percentages of the implants placed in a non-ideal

buccolingual position; 32.3% of the implants included in this study were placed in a non-ideal

buccolingual position, with 21.2 % were placed more buccally and 11.1 % were placed more

lingually.

47

Fig. 35: Buccolingual implant position histogram

4.7. Buccolingual implant angulation (buccal side)

In 104 implants the values of buccolingual implant angulation from the buccal side

ranged from 0.32 to 5.0. The mean of buccolingual implant angulation from the buccal side was

2.9 (SD=1.03). The median was 2.96 (Fig. 36).

Fig. 36: Buccolingual implant angulation (buccal side)

48

4.8. Buccolingual implant angulation (lingual side)

In 4 implants the values of buccolingual implant angulation from the lingual side ranged

from .58 to 2.1. The mean of buccolingual implant angulation from the lingual side was 1.3

(SD=0.7). The median was 1.33 (Fig. 37).

Fig. 37: Buccolingual implant angulation (lingual side)

The histogram (Fig. 38) shows the percentages of the implants placed in a non-ideal

buccolingual angulation; 4.5 % of the implants included in the study were placed in a non-ideal

buccolingual angulation, with 2.7 % were angulated more buccally and1.8 % were angulated

more lingually.

49

Fig. 38: Buccolingual implant angulation histogram

4.9. Apicocoronal implant position

In 108 implants the values of apicocoronal implant position was ranged from .04 to 5.7.

The mean of apicocoronal implant position was 2.4 (SD=1.15). The median was 2.35 (Fig. 39).

Fig. 39: Apicocoronal implant position

50

The histogram (Fig. 40) shows the percentages of the implants placed in a non-ideal

apicocoronal position; 59.2% of the implants included in the study were placed in a non-ideal

apicocoronal position, with 25.9 % were placed in a no-ideal deep apicocoronal position and

33.3 % were placed in a non-ideal shallow apicocoronal position.

Fig. 40: Apicocoronal implant position histogram

51

The percentages of the implants in a non-ideal angulation and 3D positions, which were

previously mentioned in the histograms, are summarized in the following table

Non-ideal implant

position/angulation

Total

percentage

Buccal

percentage

Lingual

percentage

Mesial

percentage

Distal

percentage

Apical

percentage

Coronal

percentage

Buccolingual

position

32.3 21.2 11.1 - - - -

Mesiodistal

position

21.28 - - 9.25 12.03 - -

Buccolingual

angulation

4.5 2.7 1.8 - - - -

Mesiodistal

angulation

0 - - 0 0 - -

Apicocoronal

position

59.2 - - - - 25.9 33.3

Table 1: summary of the implants in a non-ideal angulation and 3D position

52

3- Discussion

This retrospective study assessed angulation and three-dimensional position of the single

implants restored by predoctoral students at the Faculty of Dentistry, University of Toronto, and

determined the percentage of the implants placed in a non-ideal angulation and three-

dimensional position. The results showed that some of those implants were placed in a non-ideal

angulation and/or three-dimensional position. This study included implants that replaced teeth in

different areas of the dental arches in different patients. Accordingly, the reason(s) for the non-

ideal angulation and/or three-dimensional position may differ from one case to another and may

be due to one or more of the following reasons:

5.1. Selected implant diameter

Failure to select the proper implant diameter to correspond with the available bone

volume in the mesiodistal, buccolingual and apicocoronal dimensions is one of the reasons for a

non-ideal implant placement in the three-dimensional position (Tarnow et al. 2000). Inadequate

buccolingual distance to place the proper implant diameter may end up with thin buccal plate and

this will cause crestal bone resorption and facial marginal recession (Jansen and Weisgold1995;

Davarpanah et al. 2001).

The non-ideal three dimensional position of the implants included in this study may be

due to the improper implant diameter selection; For instance, when the mesiodistal distance at

the area of a missing molar tooth is enough to place a wide platform implant, placing a narrow

platform implant, due to inadequate buccolingual bone width, will increase the distance between

53

the implant and the adjacent tooth (more than the maximum ideal distance / 2 mm) leading to

non-ideal mesiodistal implant position.

In this study, inadequate buccal plate thickness after placing the implant would be a

reasonable explanation for the 25.9 % non-ideal deep apicocoronal implant position. This

percentage is considered relatively high since the surgeon have discussed, bone sounding,

periapical and panoramic radiographs, with the predoctoral students to evaluate the available

buccolingual bone at the implant site and estimated the remaining buccal plate thickness after

placing the proper implant diameter that corresponds with missing tooth type (i.e. molar-wide

platform, premolar-regular platform, central incisor-regular platform, lateral incisor-narrow

platform). In addition, based on the implant curriculum for predoctoral students, all patients

treated by predoctoral students should have implant site with enough bone volume to place the

implant in an ideal buccolingual position, mesiodistal and apicocoronal positions. However, this

non-ideal deep apicocoronal implant position due to inadequate buccolingual distance had

positive impact in the restoration of the implant because deep implant placement will help to

provide proper emergence profile of the restoration.

This is in agreement with Lops et al, 2008, who found that inadequate buccolingual bone

distance at the area of implant site is an explanation for deep implant placement, and there is a

relation between implant diameter and apicocoronal implant position. In addition, Spray et al.

2000 found that the facial crest resorption was more pronounced when the facial bone thickness

was decreased. A study by Kois 2001 showed that the apicocoronal implant position was

significantly associated with the facial marginal mucosal level. To confirm the positive/negative

effect of this position (25.9 % non-ideal deep apicocoronal implant position) on the implant,

clinical assessment of implants and restorations is required.

54

In regard to the mesiodistal implant position, improper implant diameter selection seems

to be another reason for the non-ideal mesiodistal position (67.6 %) in relation to the adjacent

teeth. This percentage is considered very high as the available mesiodistal distance of the implant

site was supposed to be measured by predoctoral student and the proper implant diameter was

selected based on that mesiodistal distance. The evaluation of the stone models showed that the

diameters of all implants included in the study were in corresponding with the missing teeth type

(molar-wide platform, premolar-regular platform, central incisor-regular platform, lateral incisor-

narrow platform).

Accordingly, it is concluded that improper implant diameter selection was not the main

reason for the 67.6% non-ideal mesiodistal implant position. Instead, the larger or smaller

available mesiodistal distance of the implant site, in comparison to the required mesiodistal

distance for ideal implant placement, was the reason for the non-ideal mesiodistal implant

position. That smaller or larger available mesiodistal distance for the implant site was due to

drifting of the teeth toward implant site, peg shape laterals or congenital missing teeth. The non-

ideal mesiodistal position of the implants included in this study might cause crestal bone loss

around the implant; it also might affect the height of interproximal papilla between the implant

and adjacent tooth.

This is in agreement with Esposito et al. 1993, Tarnow et al. 2000, and Romeo et al.

2008, who found that the height of the interproximal papilla is affected by the mesiodistal

position of the implant in relation to the adjacent teeth; further papillary recession and crestal

bone loss may occur as a result of placing the implant too close to the adjacent tooth.

To confirm the effects of the non-ideal mesiodistal position on the hard and soft tissues, clinical

and radiographical assessment of the implants and their restorations is required.

55

5.2. Gingival biotype

Gingival biotype affects the buccolingual and/or apicocoronal position of the implants

and it is related to severe gingival recession and presence/absence of interproximal papilla after

implant placement (Kan et al. 2003, Buser et al. 2004). A thin gingival biotype dictates

placement of the implant in a slightly more palatal position to reduce the chance of recession and

prevent the shadow of titanium from showing through the thin gingival tissue (Al-Sabbagh 2006,

Pagni et al. 2012).

The results showed that 11.1 % of the implants included in the study were placed in a

non-ideal buccolingual position (more lingually), and 25.9 % were placed in a non-ideal

apicocoronal position (more apically). Although the gingival biotype wasn’t assessed clinically,

thin gingival biotype might be one of the reasons for placing of implants included in the study in

a more lingual and/or apical position; this approach to place the implant will help to avoid

gingival recession and esthetic risk that will occur as a result of placing those implants in a more

buccal or coronal position. In this study, the assessment of implants’ positions and angulations

performed by using the stone models, thus there was no opportunity for intraoral assessment of

the soft tissue and gingival biotype.

The finding of this study is in agreement with Si et al. 2012, who found that a thin

gingival biotype requires implant placement in a slightly more lingual position to reduce the

chance of gingival recession and to prevent the shadow of the titanium from showing through the

thin gingival tissue. Consequently, the implant should be placed somewhat more apically to

avoid a ridge lapping restoration and achieve a proper emergence profile. An earlier study done

by Evans and Chen 2008 showed that there is a trend towards greater recession in a thin tissue

biotype than in a thick biotype. Our study results imply that the surgeon took these criteria into

56

account and placed implants more lingual or apical to prevent future crestal bone resorption,

gingival recession and esthetics risks.

To confirm that thin gingival biotype at the implant site is the main reason behind placing

some of the implants included in this study in a non-ideal buccolingual and/or apicocoronal

position, clinical assessment of the soft tissue at the implant site is required. In addition, this

clinical assessment is necessary to find the effect of non-ideal implant placement on severe

gingival recession and presence/absence of interproximal papilla.

5.3. Buccal cortical plate concavity

The presence of buccal plate concavity may cause non-ideal buccolingual implant

angulation and/or position. The thickness of the buccal cortical plate varies throughout the mouth

and traumatic tooth extractions can cause noticeable buccal concavities, thin plates, and overall

alveolar ridge width deficiency (Katranji et al. 2007).

A low percentage of the implants included in this study (2.7 %) were placed in a non-

ideal buccolingual angulation (more buccally), and this suggests the presence of buccal plate

concavity at the area of implant site. Regarding the non-ideal buccolingual implant position, 21.2

% of the implants were placed more buccally and 11.1 % were placed more lingually. This

percentage is considered high as the implants included in this study were placed by using the

surgical guide which was fabricated based on the tooth set up in relation to the opposing teeth.

Thus, the implants were placed more buccally or more lingually to avoid perforation of the

buccal cortical plates, which might occur due to the presence of buccal concavity at the implant

site.

57

This finding regarding the buccolingual implant position and/or angulation is in

agreement with Tinti et al. 2003, who found that some clinicians might place the implant in a

non-ideal buccolingual angulation and/or position to avoid fenestration or dehiscence implant

defect that results from placing the implant in an ideal buccolingual position and/or angulation

when there is buccal/lingual plate concavity. It is quite possible for the surgeon to place implants

in a slightly non-ideal position to avoid buccal plate perforation. To confirm the presence of

buccal cortical plate concavity as the main reason for placing those implants in a non-ideal

buccolingual angulation and/or position, clinical assessment of the implant site is required.

5.4. Implant site relation to vital anatomical structures and roots of adjacent teeth

The proximity of the implant site to the adjacent anatomical structures (e.g. maxillary

sinus, mental foramen) and/or excessive root tilting in the mesiodistal direction, that may invade

implant site, consider as one of the reasons for the non-ideal implant placement in the

mesiodistal and/or apicocoronal position (Sussman 1998).

In this study, this factor is an explanation for the non-ideal mesiodistal implant position.

The 67.6% is considered high since the radiographical assessment of implant site was assumed to

be achieved by the surgeon and predoctoral student before placing the implant. This factor is

mainly relevant to implant sites which are close to the mental foramen, maxillary sinus or

inferior alveolar nerve. The surgeon may have tried to place the implant more mesially or distally

to avoid the roots of the teeth adjacent to the implant and/or the vital anatomical structures close

to implant site, and this resulted in non-ideal mesiodistal implant position.

The non-ideal shallow apicocoronal implant placement (33.3 %) may be explained by the

proximity of the implant site to the adjacent anatomical structures. This percentage is considered

58

high as the radiographical assessment of implant site, before placing the implant, was supposed

to be achieved by the surgeon and predoctoral students. The relation of the implant to the roots of

the adjacent teeth and/or vital anatomical structures seemed to be the main reason for the non-

ideal mesiodistal and/or apicocoronal position of the implants included in this study.

The findings of this study in agreement with Misch and Wang, 2008 who found that the

clinician may try to place the implant in a non-ideal mesiodistal and/or apicocoronal positions to

avoid injury to the roots of the adjacent teeth and/or adjacent anatomical structure such as the

mental foramen and inferior alveolar nerve. To confirm the relation between findings of this

study (non-ideal implant placement in the mesiodistal and/or apicocoronal position and the

proximity of implant site to the adjacent anatomical structures and/or roots of the adjacent teeth,

radiographical assessment of the implant site is necessary. The placement of all implants

included in this study in an ideal mesiodistal angulation indicates the successful communication

between the surgeon and the predoctoral students, proper radiographical assessment, and precise

surgical guide fabrication.

4- Conclusion

1- The highest percentage of the non-ideal implant position was for the mesiodistal implant

position.

2- The lowest percentage was for the non-ideal buccolingual implant angulation.

3-The challenges in placing the implant in ideal angulations were less than that to place the

implants in ideal three-dimensional positions.

4- Cone beam CT might be considered as an aid, especially for comprised cases, in order to place

implants in an ideal angulation and/or three-dimensional position.

59

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64

Appendix A: Ethics Approval Form

65

Appendix B: Statistical Analysis Tables

Statistics

ACposition

N

Valid 108

Missing 2

Mean 2.4409

Median 2.3500

Std. Deviation 1.15626

Range 5.67

Minimum .04

Maximum 5.71

ACposition

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

.04 1 .9 .9 .9

.08 1 .9 .9 1.9

.27 1 .9 .9 2.8

.32 1 .9 .9 3.7

.65 1 .9 .9 4.6

.70 1 .9 .9 5.6

66

.89 2 1.8 1.9 7.4

.94 1 .9 .9 8.3

.99 1 .9 .9 9.3

1.00 1 .9 .9 10.2

1.01 1 .9 .9 11.1

1.05 1 .9 .9 12.0

1.08 1 .9 .9 13.0

1.13 1 .9 .9 13.9

1.14 2 1.8 1.9 15.7

1.22 1 .9 .9 16.7

1.25 1 .9 .9 17.6

1.27 1 .9 .9 18.5

1.40 1 .9 .9 19.4

1.49 1 .9 .9 20.4

1.51 2 1.8 1.9 22.2

1.60 1 .9 .9 23.1

1.61 1 .9 .9 24.1

1.67 2 1.8 1.9 25.9

1.71 1 .9 .9 26.9

1.75 1 .9 .9 27.8

1.77 1 .9 .9 28.7

67

1.79 1 .9 .9 29.6

1.89 1 .9 .9 30.6

1.90 1 .9 .9 31.5

1.92 1 .9 .9 32.4

1.95 1 .9 .9 33.3

2.00 1 .9 .9 34.3

2.01 1 .9 .9 35.2

2.03 1 .9 .9 36.1

2.06 2 1.8 1.9 38.0

2.09 1 .9 .9 38.9

2.10 1 .9 .9 39.8

2.14 2 1.8 1.9 41.7

2.19 2 1.8 1.9 43.5

2.22 1 .9 .9 44.4

2.24 1 .9 .9 45.4

2.27 1 .9 .9 46.3

2.29 3 2.7 2.8 49.1

2.34 1 .9 .9 50.0

2.36 1 .9 .9 50.9

2.47 2 1.8 1.9 52.8

2.50 1 .9 .9 53.7

68

2.51 1 .9 .9 54.6

2.55 1 .9 .9 55.6

2.60 1 .9 .9 56.5

2.62 1 .9 .9 57.4

2.66 1 .9 .9 58.3

2.69 1 .9 .9 59.3

2.72 2 1.8 1.9 61.1

2.75 2 1.8 1.9 63.0

2.76 1 .9 .9 63.9

2.79 1 .9 .9 64.8

2.80 1 .9 .9 65.7

2.82 1 .9 .9 66.7

2.84 1 .9 .9 67.6

2.85 1 .9 .9 68.5

2.88 1 .9 .9 69.4

2.92 1 .9 .9 70.4

2.93 2 1.8 1.9 72.2

2.94 1 .9 .9 73.1

3.00 1 .9 .9 74.1

3.05 1 .9 .9 75.0

3.14 1 .9 .9 75.9

69

3.17 2 1.8 1.9 77.8

3.20 2 1.8 1.9 79.6

3.21 1 .9 .9 80.6

3.33 1 .9 .9 81.5

3.36 1 .9 .9 82.4

3.37 1 .9 .9 83.3

3.45 1 .9 .9 84.3

3.54 1 .9 .9 85.2

3.69 1 .9 .9 86.1

3.79 1 .9 .9 87.0

3.84 1 .9 .9 88.0

3.89 1 .9 .9 88.9

3.90 1 .9 .9 89.8

3.94 1 .9 .9 90.7

4.00 1 .9 .9 91.7

4.11 1 .9 .9 92.6

4.13 1 .9 .9 93.5

4.46 1 .9 .9 94.4

4.72 1 .9 .9 95.4

4.76 1 .9 .9 96.3

4.95 1 .9 .9 97.2

70

5.10 1 .9 .9 98.1

5.46 1 .9 .9 99.1

5.71 1 .9 .9 100.0

Total 108 98.2 100.0

Missing System 2 1.8

Total 110 100.0

Statistics

MDpositionM

N

Valid 108

Missing 2

Mean 2.8007

Median 2.6950

Std. Deviation .93695

Range 4.10

Minimum 1.23

Maximum 5.33

MDpositionM

71

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

1.23 1 .9 .9 .9

1.31 1 .9 .9 1.9

1.37 1 .9 .9 2.8

1.44 1 .9 .9 3.7

1.49 1 .9 .9 4.6

1.56 1 .9 .9 5.6

1.59 1 .9 .9 6.5

1.61 1 .9 .9 7.4

1.70 1 .9 .9 8.3

1.74 1 .9 .9 9.3

1.76 1 .9 .9 10.2

1.77 2 1.8 1.9 12.0

1.78 1 .9 .9 13.0

1.83 2 1.8 1.9 14.8

1.85 2 1.8 1.9 16.7

1.89 1 .9 .9 17.6

1.90 1 .9 .9 18.5

1.91 1 .9 .9 19.4

1.92 1 .9 .9 20.4

72

1.93 1 .9 .9 21.3

1.95 1 .9 .9 22.2

1.96 1 .9 .9 23.1

1.97 1 .9 .9 24.1

1.99 2 1.8 1.9 25.9

2.00 1 .9 .9 26.9

2.03 1 .9 .9 27.8

2.05 1 .9 .9 28.7

2.06 1 .9 .9 29.6

2.09 1 .9 .9 30.6

2.11 2 1.8 1.9 32.4

2.13 1 .9 .9 33.3

2.14 1 .9 .9 34.3

2.17 1 .9 .9 35.2

2.19 2 1.8 1.9 37.0

2.26 1 .9 .9 38.0

2.28 1 .9 .9 38.9

2.29 2 1.8 1.9 40.7

2.47 1 .9 .9 41.7

2.51 1 .9 .9 42.6

2.52 1 .9 .9 43.5

73

2.54 1 .9 .9 44.4

2.56 1 .9 .9 45.4

2.57 1 .9 .9 46.3

2.64 1 .9 .9 47.2

2.66 1 .9 .9 48.1

2.67 2 1.8 1.9 50.0

2.72 1 .9 .9 50.9

2.73 1 .9 .9 51.9

2.75 2 1.8 1.9 53.7

2.76 1 .9 .9 54.6

2.79 1 .9 .9 55.6

2.80 1 .9 .9 56.5

2.81 1 .9 .9 57.4

2.85 1 .9 .9 58.3

3.00 1 .9 .9 59.3

3.02 1 .9 .9 60.2

3.12 1 .9 .9 61.1

3.15 1 .9 .9 62.0

3.19 1 .9 .9 63.0

3.22 1 .9 .9 63.9

3.24 1 .9 .9 64.8

74

3.27 1 .9 .9 65.7

3.32 1 .9 .9 66.7

3.33 1 .9 .9 67.6

3.34 3 2.7 2.8 70.4

3.36 1 .9 .9 71.3

3.37 1 .9 .9 72.2

3.40 1 .9 .9 73.1

3.44 1 .9 .9 74.1

3.49 1 .9 .9 75.0

3.50 1 .9 .9 75.9

3.51 1 .9 .9 76.9

3.57 1 .9 .9 77.8

3.63 1 .9 .9 78.7

3.64 1 .9 .9 79.6

3.66 1 .9 .9 80.6

3.70 1 .9 .9 81.5

3.73 1 .9 .9 82.4

3.75 1 .9 .9 83.3

3.77 2 1.8 1.9 85.2

3.79 1 .9 .9 86.1

3.82 1 .9 .9 87.0

75

3.84 1 .9 .9 88.0

3.88 1 .9 .9 88.9

3.90 1 .9 .9 89.8

3.91 1 .9 .9 90.7

4.00 1 .9 .9 91.7

4.10 1 .9 .9 92.6

4.24 1 .9 .9 93.5

4.32 1 .9 .9 94.4

4.34 1 .9 .9 95.4

4.78 1 .9 .9 96.3

4.83 1 .9 .9 97.2

4.96 1 .9 .9 98.1

5.22 1 .9 .9 99.1

5.33 1 .9 .9 100.0

Total 108 98.2 100.0

Missing System 2 1.8

Total 110 100.0

Statistics

MDpositionM

N Valid 108

76

Missing 2

Mean 2.8007

Median 2.6950

Std. Deviation .93695

Range 4.10

Minimum 1.23

Maximum 5.33

MDpositionM

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

1.23 1 .9 .9 .9

1.31 1 .9 .9 1.9

1.37 1 .9 .9 2.8

1.44 1 .9 .9 3.7

1.49 1 .9 .9 4.6

1.56 1 .9 .9 5.6

1.59 1 .9 .9 6.5

1.61 1 .9 .9 7.4

1.70 1 .9 .9 8.3

1.74 1 .9 .9 9.3

77

1.76 1 .9 .9 10.2

1.77 2 1.8 1.9 12.0

1.78 1 .9 .9 13.0

1.83 2 1.8 1.9 14.8

1.85 2 1.8 1.9 16.7

1.89 1 .9 .9 17.6

1.90 1 .9 .9 18.5

1.91 1 .9 .9 19.4

1.92 1 .9 .9 20.4

1.93 1 .9 .9 21.3

1.95 1 .9 .9 22.2

1.96 1 .9 .9 23.1

1.97 1 .9 .9 24.1

1.99 2 1.8 1.9 25.9

2.00 1 .9 .9 26.9

2.03 1 .9 .9 27.8

2.05 1 .9 .9 28.7

2.06 1 .9 .9 29.6

2.09 1 .9 .9 30.6

2.11 2 1.8 1.9 32.4

2.13 1 .9 .9 33.3

78

2.14 1 .9 .9 34.3

2.17 1 .9 .9 35.2

2.19 2 1.8 1.9 37.0

2.26 1 .9 .9 38.0

2.28 1 .9 .9 38.9

2.29 2 1.8 1.9 40.7

2.47 1 .9 .9 41.7

2.51 1 .9 .9 42.6

2.52 1 .9 .9 43.5

2.54 1 .9 .9 44.4

2.56 1 .9 .9 45.4

2.57 1 .9 .9 46.3

2.64 1 .9 .9 47.2

2.66 1 .9 .9 48.1

2.67 2 1.8 1.9 50.0

2.72 1 .9 .9 50.9

2.73 1 .9 .9 51.9

2.75 2 1.8 1.9 53.7

2.76 1 .9 .9 54.6

2.79 1 .9 .9 55.6

2.80 1 .9 .9 56.5

79

2.81 1 .9 .9 57.4

2.85 1 .9 .9 58.3

3.00 1 .9 .9 59.3

3.02 1 .9 .9 60.2

3.12 1 .9 .9 61.1

3.15 1 .9 .9 62.0

3.19 1 .9 .9 63.0

3.22 1 .9 .9 63.9

3.24 1 .9 .9 64.8

3.27 1 .9 .9 65.7

3.32 1 .9 .9 66.7

3.33 1 .9 .9 67.6

3.34 3 2.7 2.8 70.4

3.36 1 .9 .9 71.3

3.37 1 .9 .9 72.2

3.40 1 .9 .9 73.1

3.44 1 .9 .9 74.1

3.49 1 .9 .9 75.0

3.50 1 .9 .9 75.9

3.51 1 .9 .9 76.9

3.57 1 .9 .9 77.8

80

3.63 1 .9 .9 78.7

3.64 1 .9 .9 79.6

3.66 1 .9 .9 80.6

3.70 1 .9 .9 81.5

3.73 1 .9 .9 82.4

3.75 1 .9 .9 83.3

3.77 2 1.8 1.9 85.2

3.79 1 .9 .9 86.1

3.82 1 .9 .9 87.0

3.84 1 .9 .9 88.0

3.88 1 .9 .9 88.9

3.90 1 .9 .9 89.8

3.91 1 .9 .9 90.7

4.00 1 .9 .9 91.7

4.10 1 .9 .9 92.6

4.24 1 .9 .9 93.5

4.32 1 .9 .9 94.4

4.34 1 .9 .9 95.4

4.78 1 .9 .9 96.3

4.83 1 .9 .9 97.2

4.96 1 .9 .9 98.1

81

5.22 1 .9 .9 99.1

5.33 1 .9 .9 100.0

Total 108 98.2 100.0

Missing System 2 1.8

Total 110 100.0

Statistics

MDpositionD

N

Valid 108

Missing 2

Mean 2.4865

Median 2.3650

Std. Deviation .79488

Range 3.91

Minimum .64

Maximum 4.55

MDpositionD

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

82

Valid

.64 1 .9 .9 .9

.89 1 .9 .9 1.9

.96 1 .9 .9 2.8

1.07 1 .9 .9 3.7

1.28 1 .9 .9 4.6

1.29 1 .9 .9 5.6

1.42 1 .9 .9 6.5

1.45 1 .9 .9 7.4

1.49 1 .9 .9 8.3

1.52 1 .9 .9 9.3

1.58 2 1.8 1.9 11.1

1.60 1 .9 .9 12.0

1.65 1 .9 .9 13.0

1.73 1 .9 .9 13.9

1.79 1 .9 .9 14.8

1.83 1 .9 .9 15.7

1.85 1 .9 .9 16.7

1.87 2 1.8 1.9 18.5

1.89 1 .9 .9 19.4

1.90 2 1.8 1.9 21.3

1.92 1 .9 .9 22.2

83

1.95 1 .9 .9 23.1

1.96 1 .9 .9 24.1

1.99 3 2.7 2.8 26.9

2.01 1 .9 .9 27.8

2.03 2 1.8 1.9 29.6

2.05 1 .9 .9 30.6

2.06 1 .9 .9 31.5

2.07 1 .9 .9 32.4

2.10 1 .9 .9 33.3

2.11 1 .9 .9 34.3

2.14 1 .9 .9 35.2

2.15 1 .9 .9 36.1

2.17 1 .9 .9 37.0

2.19 1 .9 .9 38.0

2.20 1 .9 .9 38.9

2.22 1 .9 .9 39.8

2.23 1 .9 .9 40.7

2.24 1 .9 .9 41.7

2.25 1 .9 .9 42.6

2.26 1 .9 .9 43.5

2.27 2 1.8 1.9 45.4

84

2.28 1 .9 .9 46.3

2.31 1 .9 .9 47.2

2.32 1 .9 .9 48.1

2.33 1 .9 .9 49.1

2.36 1 .9 .9 50.0

2.37 1 .9 .9 50.9

2.38 1 .9 .9 51.9

2.39 2 1.8 1.9 53.7

2.40 1 .9 .9 54.6

2.41 2 1.8 1.9 56.5

2.42 2 1.8 1.9 58.3

2.46 2 1.8 1.9 60.2

2.47 1 .9 .9 61.1

2.56 1 .9 .9 62.0

2.57 1 .9 .9 63.0

2.59 1 .9 .9 63.9

2.60 1 .9 .9 64.8

2.63 1 .9 .9 65.7

2.65 1 .9 .9 66.7

2.66 1 .9 .9 67.6

2.67 1 .9 .9 68.5

85

2.71 1 .9 .9 69.4

2.78 1 .9 .9 70.4

2.81 1 .9 .9 71.3

2.83 1 .9 .9 72.2

2.88 1 .9 .9 73.1

2.94 1 .9 .9 74.1

2.98 1 .9 .9 75.0

3.04 1 .9 .9 75.9

3.05 1 .9 .9 76.9

3.06 1 .9 .9 77.8

3.11 1 .9 .9 78.7

3.14 1 .9 .9 79.6

3.17 1 .9 .9 80.6

3.18 1 .9 .9 81.5

3.23 1 .9 .9 82.4

3.36 1 .9 .9 83.3

3.41 1 .9 .9 84.3

3.43 1 .9 .9 85.2

3.48 1 .9 .9 86.1

3.49 1 .9 .9 87.0

3.64 1 .9 .9 88.0

86

3.65 1 .9 .9 88.9

3.67 1 .9 .9 89.8

3.70 1 .9 .9 90.7

3.71 1 .9 .9 91.7

3.78 1 .9 .9 92.6

3.81 1 .9 .9 93.5

3.93 1 .9 .9 94.4

3.95 1 .9 .9 95.4

3.99 1 .9 .9 96.3

4.04 1 .9 .9 97.2

4.19 1 .9 .9 98.1

4.44 1 .9 .9 99.1

4.55 1 .9 .9 100.0

Total 108 98.2 100.0

Missing System 2 1.8

Total 110 100.0

Statistics

BLpositionB

N

Valid 95

Missing 15

87

Mean 2.0428

Median 1.9700

Std. Deviation 1.03924

Range 5.94

Minimum -.93

Maximum 5.01

BLpositionB

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

-.93 1 .9 1.1 1.1

-.36 1 .9 1.1 2.1

.12 1 .9 1.1 3.2

.23 1 .9 1.1 4.2

.44 1 .9 1.1 5.3

.49 1 .9 1.1 6.3

.52 1 .9 1.1 7.4

.61 1 .9 1.1 8.4

.68 1 .9 1.1 9.5

.69 1 .9 1.1 10.5

.76 1 .9 1.1 11.6

88

.81 1 .9 1.1 12.6

.87 1 .9 1.1 13.7

.97 1 .9 1.1 14.7

1.02 1 .9 1.1 15.8

1.03 1 .9 1.1 16.8

1.18 2 1.8 2.1 18.9

1.24 1 .9 1.1 20.0

1.25 1 .9 1.1 21.1

1.27 1 .9 1.1 22.1

1.39 1 .9 1.1 23.2

1.43 1 .9 1.1 24.2

1.50 1 .9 1.1 25.3

1.51 1 .9 1.1 26.3

1.52 1 .9 1.1 27.4

1.53 1 .9 1.1 28.4

1.54 2 1.8 2.1 30.5

1.55 1 .9 1.1 31.6

1.56 3 2.7 3.2 34.7

1.57 2 1.8 2.1 36.8

1.60 1 .9 1.1 37.9

1.66 2 1.8 2.1 40.0

89

1.67 2 1.8 2.1 42.1

1.70 1 .9 1.1 43.2

1.72 1 .9 1.1 44.2

1.80 1 .9 1.1 45.3

1.87 1 .9 1.1 46.3

1.90 1 .9 1.1 47.4

1.92 1 .9 1.1 48.4

1.93 1 .9 1.1 49.5

1.97 1 .9 1.1 50.5

2.01 1 .9 1.1 51.6

2.06 1 .9 1.1 52.6

2.08 1 .9 1.1 53.7

2.11 1 .9 1.1 54.7

2.15 1 .9 1.1 55.8

2.17 1 .9 1.1 56.8

2.22 1 .9 1.1 57.9

2.23 1 .9 1.1 58.9

2.25 1 .9 1.1 60.0

2.29 1 .9 1.1 61.1

2.30 1 .9 1.1 62.1

2.41 1 .9 1.1 63.2

90

2.44 1 .9 1.1 64.2

2.52 1 .9 1.1 65.3

2.60 1 .9 1.1 66.3

2.63 1 .9 1.1 67.4

2.64 2 1.8 2.1 69.5

2.65 1 .9 1.1 70.5

2.67 1 .9 1.1 71.6

2.68 1 .9 1.1 72.6

2.76 1 .9 1.1 73.7

2.83 1 .9 1.1 74.7

2.89 2 1.8 2.1 76.8

2.90 1 .9 1.1 77.9

2.99 1 .9 1.1 78.9

3.02 1 .9 1.1 80.0

3.03 2 1.8 2.1 82.1

3.04 2 1.8 2.1 84.2

3.06 1 .9 1.1 85.3

3.10 1 .9 1.1 86.3

3.16 2 1.8 2.1 88.4

3.20 1 .9 1.1 89.5

3.24 1 .9 1.1 90.5

91

3.27 1 .9 1.1 91.6

3.37 1 .9 1.1 92.6

3.54 1 .9 1.1 93.7

3.69 1 .9 1.1 94.7

3.84 2 1.8 2.1 96.8

3.86 1 .9 1.1 97.9

4.09 1 .9 1.1 98.9

5.01 1 .9 1.1 100.0

Total 95 86.4 100.0

Missing System 15 13.6

Total 110 100.0

Statistics

BLpositionL

N

Valid 13

Missing 97

Mean .9746

Median 1.1800

Std. Deviation .51654

Range 1.90

Minimum .03

92

Maximum 1.93

BLpositionL

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

.03 1 .9 7.7 7.7

.24 1 .9 7.7 15.4

.48 1 .9 7.7 23.1

.77 1 .9 7.7 30.8

.78 1 .9 7.7 38.5

.86 1 .9 7.7 46.2

1.18 1 .9 7.7 53.8

1.20 1 .9 7.7 61.5

1.26 1 .9 7.7 69.2

1.29 1 .9 7.7 76.9

1.32 1 .9 7.7 84.6

1.33 1 .9 7.7 92.3

1.93 1 .9 7.7 100.0

Total 13 11.8 100.0

Missing System 97 88.2

Total 110 100.0

93

Statistics

MDangulationM

N

Valid 55

Missing 55

Mean 2.7769

Median 2.7200

Std. Deviation .84135

Range 3.37

Minimum 1.26

Maximum 4.63

MDangulationM

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

1.26 1 .9 1.8 1.8

1.46 1 .9 1.8 3.6

1.48 1 .9 1.8 5.5

1.55 1 .9 1.8 7.3

1.69 2 1.8 3.6 10.9

94

1.77 1 .9 1.8 12.7

1.89 1 .9 1.8 14.5

1.91 1 .9 1.8 16.4

1.98 1 .9 1.8 18.2

2.05 1 .9 1.8 20.0

2.07 1 .9 1.8 21.8

2.08 1 .9 1.8 23.6

2.12 1 .9 1.8 25.5

2.13 2 1.8 3.6 29.1

2.17 1 .9 1.8 30.9

2.19 1 .9 1.8 32.7

2.26 1 .9 1.8 34.5

2.33 1 .9 1.8 36.4

2.39 1 .9 1.8 38.2

2.55 2 1.8 3.6 41.8

2.60 2 1.8 3.6 45.5

2.62 1 .9 1.8 47.3

2.65 1 .9 1.8 49.1

2.72 1 .9 1.8 50.9

2.79 2 1.8 3.6 54.5

2.83 2 1.8 3.6 58.2

95

2.88 1 .9 1.8 60.0

2.92 1 .9 1.8 61.8

2.98 1 .9 1.8 63.6

3.02 1 .9 1.8 65.5

3.03 1 .9 1.8 67.3

3.19 1 .9 1.8 69.1

3.26 1 .9 1.8 70.9

3.27 1 .9 1.8 72.7

3.34 2 1.8 3.6 76.4

3.35 1 .9 1.8 78.2

3.59 1 .9 1.8 80.0

3.62 1 .9 1.8 81.8

3.68 1 .9 1.8 83.6

3.82 1 .9 1.8 85.5

3.83 1 .9 1.8 87.3

3.93 1 .9 1.8 89.1

3.95 1 .9 1.8 90.9

3.99 1 .9 1.8 92.7

4.06 1 .9 1.8 94.5

4.38 1 .9 1.8 96.4

4.54 1 .9 1.8 98.2

96

4.63 1 .9 1.8 100.0

Total 55 50.0 100.0

Missing System 55 50.0

Total 110 100.0

Statistics

MDangulationD

N

Valid

53

Missing 57

Mean 2.7413

Median 2.6600

Std. Deviation .75883

Range 3.18

Minimum 1.40

Maximum 4.58

MDangulationD

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

97

Valid

1.40 1 .9 1.9 1.9

1.55 1 .9 1.9 3.8

1.66 1 .9 1.9 5.7

1.79 2 1.8 3.8 9.4

1.82 1 .9 1.9 11.3

1.83 1 .9 1.9 13.2

1.87 1 .9 1.9 15.1

1.94 1 .9 1.9 17.0

1.95 1 .9 1.9 18.9

1.98 1 .9 1.9 20.8

2.07 1 .9 1.9 22.6

2.08 2 1.8 3.8 26.4

2.16 1 .9 1.9 28.3

2.24 1 .9 1.9 30.2

2.30 1 .9 1.9 32.1

2.40 1 .9 1.9 34.0

2.46 1 .9 1.9 35.8

2.47 1 .9 1.9 37.7

2.54 2 1.8 3.8 41.5

2.55 1 .9 1.9 43.4

2.59 1 .9 1.9 45.3

98

2.61 1 .9 1.9 47.2

2.63 1 .9 1.9 49.1

2.66 1 .9 1.9 50.9

2.72 1 .9 1.9 52.8

2.77 1 .9 1.9 54.7

2.80 1 .9 1.9 56.6

2.83 1 .9 1.9 58.5

2.86 1 .9 1.9 60.4

2.92 2 1.8 3.8 64.2

3.00 1 .9 1.9 66.0

3.01 1 .9 1.9 67.9

3.04 1 .9 1.9 69.8

3.08 2 1.8 3.8 73.6

3.17 1 .9 1.9 75.5

3.29 1 .9 1.9 77.4

3.30 1 .9 1.9 79.2

3.36 1 .9 1.9 81.1

3.41 1 .9 1.9 83.0

3.50 1 .9 1.9 84.9

3.67 1 .9 1.9 86.8

3.68 1 .9 1.9 88.7

99

3.90 1 .9 1.9 90.6

3.92 1 .9 1.9 92.5

3.98 1 .9 1.9 94.3

4.06 1 .9 1.9 96.2

4.48 1 .9 1.9 98.1

4.58 1 .9 1.9 100.0

Total 53 48.2 100.0

Missing System 57 51.8

Total 110 100.0

Statistics

BLangulationB

N

Valid 104

Missing 6

Mean 2.9244

Median 2.9650

Std. Deviation 1.03559

Range 4.67

Minimum .32

Maximum 4.99

100

BLangulationB

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

.32 1 .9 1.0 1.0

.62 1 .9 1.0 1.9

.88 1 .9 1.0 2.9

1.06 1 .9 1.0 3.8

1.20 1 .9 1.0 4.8

1.27 1 .9 1.0 5.8

1.32 1 .9 1.0 6.7

1.38 1 .9 1.0 7.7

1.44 1 .9 1.0 8.7

1.49 1 .9 1.0 9.6

1.50 2 1.8 1.9 11.5

1.65 1 .9 1.0 12.5

1.67 1 .9 1.0 13.5

1.68 1 .9 1.0 14.4

1.75 2 1.8 1.9 16.3

1.80 1 .9 1.0 17.3

1.85 1 .9 1.0 18.3

1.91 1 .9 1.0 19.2

2.11 1 .9 1.0 20.2

101

2.12 1 .9 1.0 21.2

2.14 1 .9 1.0 22.1

2.16 1 .9 1.0 23.1

2.17 2 1.8 1.9 25.0

2.18 1 .9 1.0 26.0

2.22 1 .9 1.0 26.9

2.26 1 .9 1.0 27.9

2.27 1 .9 1.0 28.8

2.30 1 .9 1.0 29.8

2.33 1 .9 1.0 30.8

2.41 1 .9 1.0 31.7

2.44 1 .9 1.0 32.7

2.46 1 .9 1.0 33.7

2.49 1 .9 1.0 34.6

2.56 1 .9 1.0 35.6

2.59 1 .9 1.0 36.5

2.62 1 .9 1.0 37.5

2.66 1 .9 1.0 38.5

2.69 2 1.8 1.9 40.4

2.73 2 1.8 1.9 42.3

2.77 1 .9 1.0 43.3

102

2.80 3 2.7 2.9 46.2

2.85 1 .9 1.0 47.1

2.87 1 .9 1.0 48.1

2.89 1 .9 1.0 49.0

2.94 1 .9 1.0 50.0

2.99 1 .9 1.0 51.0

3.00 1 .9 1.0 51.9

3.09 1 .9 1.0 52.9

3.10 2 1.8 1.9 54.8

3.16 1 .9 1.0 55.8

3.17 1 .9 1.0 56.7

3.18 3 2.7 2.9 59.6

3.19 1 .9 1.0 60.6

3.24 1 .9 1.0 61.5

3.27 1 .9 1.0 62.5

3.37 2 1.8 1.9 64.4

3.40 1 .9 1.0 65.4

3.43 1 .9 1.0 66.3

3.44 2 1.8 1.9 68.3

3.47 1 .9 1.0 69.2

3.49 1 .9 1.0 70.2

103

3.50 1 .9 1.0 71.2

3.61 1 .9 1.0 72.1

3.64 3 2.7 2.9 75.0

3.67 1 .9 1.0 76.0

3.69 1 .9 1.0 76.9

3.71 1 .9 1.0 77.9

3.73 1 .9 1.0 78.8

3.77 1 .9 1.0 79.8

3.89 1 .9 1.0 80.8

3.90 1 .9 1.0 81.7

3.95 1 .9 1.0 82.7

3.97 1 .9 1.0 83.7

4.00 1 .9 1.0 84.6

4.02 1 .9 1.0 85.6

4.06 1 .9 1.0 86.5

4.07 2 1.8 1.9 88.5

4.12 1 .9 1.0 89.4

4.23 1 .9 1.0 90.4

4.29 1 .9 1.0 91.3

4.37 1 .9 1.0 92.3

4.47 1 .9 1.0 93.3

104

4.52 1 .9 1.0 94.2

4.58 1 .9 1.0 95.2

4.66 1 .9 1.0 96.2

4.93 1 .9 1.0 97.1

4.95 1 .9 1.0 98.1

4.98 1 .9 1.0 99.0

4.99 1 .9 1.0 100.0

Total 104 94.5 100.0

Missing System 6 5.5

Total 110 100.0

Statistics

BLangulationL

N

Valid 4

Missing 106

Mean 1.3400

Median 1.3350

Std. Deviation .70299

Range 1.53

Minimum .58

Maximum 2.11

105

BLangulation

Frequenc

y

Percent Valid

Percent

Cumulative

Percent

Valid

.58 1 .9 25.0 25.0

.94 1 .9 25.0 50.0

1.73 1 .9 25.0 75.0

2.11 1 .9 25.0 100.0

Total 4 3.6 100.0

Missing System 106 96.4

Total 110 100.0