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ORIGINAL ARTICLE

Changes in soft tissue profile after orthodontictreatment with and without extractions

Ilken Kocadereli, DDS, PhD

Ankara, Turkey

The effects of orthodontic treatment on the facial profile, with or without the extraction of teeth, have greatly

concerned orthodontists. A study was made of 80 patients with Angle Class I malocclusion. Forty patients

(24 girls, 16 boys) did not undergo extraction of teeth, and 40 patients (23 girls, 17 boys) underwent extraction

of maxillary and mandibular first premolars. Data were obtained from the corresponding lateral radiographs

of the head taken before and after orthodontic treatment. The purpose of this study was to compare the

response of the soft tissue of the facial profile in Class I malocclusions treated with and without the extraction

of the 4 first premolars. The main soft tissue differences between the groups at the end of treatment were

more retruded upper and lower lips in the extraction patients. (Am J Orthod Dentofacial Orthop 2002;122:

67-72)

Evaluating facial profiles and facial balance is a

continuous learning process for orthodontists.

The debate concerning the extraction of teeth

and its effect on the facial profile began more than 100

years ago. Many studies concerned with the effects of

orthodontic treatment on the facial profile have focused

on predictive aspects of the relationship between the

incisors and the lips; the goal was to relate changes in

incisor position to changes in lip protrusion.1-8

Proffit,

9

analyzing data from the orthodontic clinicat the University of North Carolina, indicated that

changes in extraction frequencies over the past 40 years

are almost entirely due to an increase and then a

decrease in the extraction of the 4 first premolars. The

initial increase (1953-1963) occurred primarily in a

search for greater long-term stability; the more recent

decline (1983-1993) seems to be due to several factors,

including greater concern about the impact of extrac-

tion on facial esthetics, data suggesting that extraction

does not guarantee stability, concern about temporo-

mandibular dysfunction, and changes in technique.

Orthodontists have long recognized that the extrac-tion of premolars often is accompanied by changes in

the soft tissue profile. At times, these changes result in

substantial improvements in the profile and frequently

justify the extraction of teeth in patients without other

indications. At other times, however, premolar extrac-

tion can lead to a flatter profile.10

The purpose of this study was to compare the soft

tissue profile changes in patients with Class I maloc-

clusions who were treated with 4 first premolar extrac-

tions with a group of patients treated with similar

appliances but without extractions.

MATERIAL AND METHODS

A study included 80 white patients presenting with

Angle Class I malocclusions. None of them had a

severe craniofacial anomaly, and all were to be treated

with edgewise appliances. No teeth were extracted in

40 patients (24 girls, 16 boys); 4 first premolars were

extracted in 40 (23 girls, 17 boys). The mean ages of

the patients at the beginning of treatment were similar

in both groups: 12.82 2.37 years for the extraction

group and 12.31 2.19 years for the nonextraction

group. The average treatment times were 26.35

13.25 months for the nonextraction group and 31.53

14.10 months for the extraction group. At the end of

treatment, all patients were considered to be welltreated, displayed Class I canine and molar relation-

ships, and had overbites between 10% and 25%; both

dental arches were well aligned, with teeth interdigi-

tated.

In the nonextraction group, crowding was 3.18

2.18 mm in the maxilla and 3.15 1.86 mm in the

mandible. In the extraction group, crowding was

7.20 2.44 mm in the maxilla and 5.35 2.50 mm in

the mandible. The decision of whether to extract was

based on an evaluation of the need for space to align the

teeth (crowding shown by arch lengthtooth size anal-

Associate professor, Department of Orthodontics, Faculty of Dentistry, Hacet-

tepe University, Ankara, Turkey

Reprint requests to: Dr I

lken Kocadereli, Suslu Sokak No: 4/6, Mebusevleri-

Tandogan, 06580 Ankara, Turkey; e-mail, [email protected].

Submitted, April 2001; revised and accepted, November 2001.

Copyright 2002 by the American Association of Orthodontists.

0889-5406/2002/$35.00 0 8/1/125235

doi:10.1067/mod.2002.125235

67


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ysis) and the cephalometric position of the mandibular

incisors.

Data were obtained from lateral cephalometric ra-

diographs taken before and after orthodontic treatment,

with the patient in a standing position, the teeth inocclusion, and the lips relaxed. The patients were asked

to close on the molars and not to stress the lips. All

cephalograms were obtained on the same cephalometric

unit. All landmarks were identified by 1 investigator

(I.K.) and checked for accuracy of location. All radio-

graphs were traced by the same person (I.K.) and

digitized with an RMO JOE (Rocky Mountain Orth-

odontics, Denver, Colo). The landmarks were digitized

twice on separate occasions by the same investigator.

Allowable intrainvestigator discrepancies were prede-

termined at 0.5 mm and 0.5.

The cephalograms were oriented with the facial

profile to the right. The cephalometric points, lines, and

measurements used in this study to evaluate the

changes in the soft tissue facial profile are defined in

Table I. The linear and angular measurements areshown in Figures 1 and 2.

Values reported in this study were calculated by

subtracting the pretreatment value from the posttreatment

value. Thus, a nasolabial angle that becomes more obtuse

during treatment would have a positive value. Retraction

of the lips relative to the E-line and Sn-Pog line would

have a negative value because a measurement to the left

of the reference line was recorded as negative. For

example, a typical change for upper lip to E-line would

be recorded as (5) (1)4. A typical change for

upper lip to Sn-Pog would be from 4 mm pretreat-

Table I. Cephalometric points, lines, and angles used to evaluate changes in soft tissue pro file

Points

Nt, nose tip Most anterior point on sagittal contour of nose

Sn, subnasale Point at junction of columella and upper lip

S s, sulcus superior Poi nt of greate st concavity be twee n labra le superior a nd subnasaleLs, labrale superior Most anterior point on convexity of upper lip

Li, labrale inferior Most anterior point on convexity of lower lip

Si, sulcus inferior Point of greatest concavity between labrale inferior and soft-tissue pogonion

Pog, soft -tissue pogonion Most a nt erior poi nt on soft-t issue chin

A, Poi nt A Poi nt at de epest midline conc avity on maxilla betwe en ante rior nasal spine and prosthion

B, Point B Point at deepest midline concavity on mandibular symphysis between infradentale and

pogonion

Na, nasion Most anterior point of frontonasal suture in median plane

Or, orbitale Lowest point in inferior margin of orbit, midpoint between right and left images

Po, porion Superior point of external auditory meatus

Pog, pogonion Most anterior point of bony chin in median plane

Lines

E-line Esthetic line proposed by Ricketts, extending between Nt and Pog

Subnasale-pogonion plane Line proposed by Burstone to measure labial protrusion, extending between Sn and Pog

H-line Harmony line proposed by Holdaway, tangential to Pog and Ls

Profile line Line tangent to soft tissue chin and most prominent lip

Frankfort horizontal plane Horizontal plane running through porion and orbitale

NA line Line extending between nasion and Point A

NB line Line extending between nasion and Point B

APog line Line extending between Point A and pogonion

Axial inclination of maxillary incisor

Axial inclination of mandibular incisor

Angles

Z-angle () Inner inferior angle formed by intersection of Frankfort horizontal plane and profile line

Nasolabial angle () Formed by intersection of line originating in Sn, tangent to lower margin of nose, and line

traced between Sn and Ls

Labiomental angle () Formed by intersecti on of line tra ced between Li and Si, and line tra ced bet ween Si a nd

Pog

H-angle () Formed by intersection of NB line and harmony (H) lineMaxillary incisor-NA () Formed by intersection of maxillary incisor axial inclination and nasion-Point A line

Maxillary incisor-APog () Formed by intersection of maxillary incisor axial inclination and Point A-pogonion line

Mandibular incisor-NB () Formed by intersection of mandibular incisor axial inclination and nasion-Point B line

Mandibular incisor-APog line () Formed by intersection of mandibular incisor axial inclination and Point A-pogonion line

Interincisal angle () Formed by intersecti on of maxillary and mandibul ar incisor a xial i nc lina tions

American Journal of Orthodontics and Dentofacial Orthopedics

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68 Kocadereli


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ment to 2 mm posttreatment, recorded as (4)

(2) 2. The groups were compared with t tests.

RESULTS

Table II lists descriptive statistics for changes in

facial profile after orthodontic treatment with extraction

of 4 first premolars and nonextraction. The changes in

maxillary and mandibular incisors to APog line (angu-

lar and linear) were statistically significant (P .05).

The changes in mandibular incisor-NB (), maxillary

incisor-NA (), maxillary incisor-NA (mm), mandibu-

lar lipE-line (mm), and subnasale-Poglabiale infe-

rior (mm) were statistically significant (P .05). The

changes in H-angle, labiomental angle, sulcus superiorE-line, and sulcus inferiorE-line were not statistically

significant (P .05).

For the extraction group, the maxillary and man-

dibular incisors showed a retroclination during treat-

ment. In the nonextraction group, a forward tipping of

the incisors was noted. The changes in incisor inclina-

tion proved to be significant.

DISCUSSION

The study of beauty and harmony of the facial

profile has been central to the practice of orthodontics

from its earliest days. The main purpose of the present

study was to compare the effects of first premolar

extraction on the facial profile between a sample of

patients when 4 first premolar extractions were consid-

ered necessary and a similar sample when a conserva-

tive treatment was adopted.

Lip structure seems to have an influence on lip

response to incisor retraction. In an attempt to deter-

mine the effects of incisor retraction on the profile,

several studies have been conducted to quantify and

predict the relationship between incisor retraction and

lip retraction.11-16

Measurement of the lips relative to Ricketts16

E-line and Burstones17,18 subnasalesoft tissue pogo-nion (Sn-Pog) line focuses attention on the relationship

of nose, lips, and chin. In both groups, the upper and the

lower lips were less protrusive after treatment. In the

extraction group, the upper and the lower lips moved

back relative to the E-line and Sn-Pog line. For the

nonextraction group, the backward change of the lip

region was less pronounced. At the end of treatment in

this study, the mean values for upper and lower lips

were slightly more protrusive than Ricketts esthetic

ideal.16 Taking into account the flexible and mobile lip

texture, a rather large variability in lip position can be

Fig 1. Linear cephalometric measurements (mm): 1,

sulcus superiorE line; 2, subnasale-pogonion plane

labrale superior; 3, labrale superiorE-line; 4, subna-

sale-pogonion planelabrale inferior; 5, labrale inferior

E-line; 6, sulcus inferiorE-line; 7, lower incisornasion _

Point B line; 8, lower incisorPoint A_Pogonion line; 9,

upper incisornasion_Point A line; 10, upper incisor

Point A_ pogonion line.

Fig 2. Angular cephalometric measurements (): 1, Z-

angle; 2, nasolabial angle; 3, labiomental angle; 4,

H-angle; 5, upper incisorNA; 6, upper incisorAPog; 7,

lower incisorNB; 8, lower incisorAPog line; 9, interin-

cisal angle.


Volume 122, Number 1

Kocadereli 69


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expected on lateral cephalograms even when patients

are instructed to keep their lips relaxed and their teeth

in occlusion.19 The lip extension can easily adapt to

incisor displacements and become wider or narrower,due to extensive mobility.20 When lip position is

evaluated in the framework of the growing nose and

chin, the lips drop slightly backward as the nose and the

chin grow forward to a greater extent than the lip

regions. This relatively backward evolution of the lips

remains within conventional esthetic prescriptions. The

lip movement in the nonextraction group proved to be

less important than the effect of nose and chin growth

because, even in this group, the lip regions moved

backward with respect to the nose-chin line. Lip struc-

ture seems to have an influence on lip response to

incisor retraction. Oliver4 found that patients with thin

lips or a high lip strain displayed a significant correla-

tion between incisor retraction and lip retraction, but

patients with thick lips or low lip strain displayed nosuch correlation. In addition, Wisth15 found that lip

response, as a proportion of incisor retraction, de-

creased as the amount of incisor retraction increased.

This seems to indicate that the lips have some inherent

support.

In this study, for the extraction group, the maxillary

and mandibular incisors showed greater retroclination

after treatment than before. In the nonextraction group,

a forward tipping of the incisors after treatment was

noted. The changes in incisor inclination proved to be

significant. When compared with the normative value

Table II. Changes in facial profile

Initial Final Difference

Extraction Nonextraction P Extraction Nonextraction P Extraction Nonextraction P

Sulcus superior -

E-line (mm)

10.2 2.3 9.4 2.4 10.7 2.3 10.4 2.1 0.47 1.6 0.95 1.9

Sn-Pog

labrale

superior (mm)

4.2 2.1 3.6 2.0 3.2 1.7 3.6 2.0 0.9 1.5 0.05 1.6 *

Labrale superior

- E-line (mm)

3.0 3.4 3.0 2.9 4.1 2.7 3.5 2.9 1 1.9 0.4 2.2

Sn-Pog - labrale

inferior (mm)

4.3 2.6 3.1 2.3 * 3.2 2.2 3.5 2.3 1.1 1.4 0.5 1.9 **

Labrale inferior -

E-line (mm)

0.6 3.7 1 3.1 1.4 3.2 1 2.9 1.1 2.0 0.08 2.4 **

Sulcus inferior -

E-line (mm)

5.0 2.8 5.2 2.4 5.7 2.4 5.2 2.8 0.76 1.6 0.26 1.7

Mand1 - NB line

(mm)

5.4 2.2 4.1 1.5 * 4.8 1.5 5.4 1.8 0.4 1.6 1.3 1.5 **

Mand1 - APog

line (mm)

3.2 2.4 2.0 2.5 * 2.5 2.1 3.9 2.5 * 0.7 1.8 1.9 2.2 **

Max1 NA line

(mm)

4.8 2.2 4.5 1.5 4.2 1.8 5.5 2.0 * 0.6 2.4 1.0 2.0 **

Max1 - APog

line (mm)

6.9 3.0 5.6 2.8 * 5.5 1.8 6.8 2.5 * 1.1 2.2 1.1 2.0 **

Z-angle () 67.5 8.9 71.5 7.4 * 69.1 8.2 71.7 6.4 1.8 4.7 0.09 4.7

Nasolabial angle

()

121.7 18.9 131.8 21 ** 126.5 16.3 128.5 18.7 4.8 23 0.47 24.7

Labiomental

angle ()

139.4 10.5 137.5 12.4 139.7 10.3 137.1 9.5 0.36 10.6 0.05 11.38

H-angle () 4.8 4 5.2 3.7 5.9 3.6 5.2 3.6 1.1 2.6 0.1 2.9

Max1 - NA () 21.9 5.4 20.8 6.1 20.3 7.0 25.5 6.3 ** 1.5 6.6 4.5 6.0 **

Max1 - APog () 28.8 7.2 26.1 6.2 25.9 5.1 29.1 5.8 * 2.4 6.3 2.5 6.6 **

Mand1 - NB () 25.8 6.5 22.9 7.3 23.1 6.5 27.3 7.5 * 1.9 6.6 3.8 6.4 **

Mand1 - APog

()

22.5 4.0 20.9 5.6 20.9 5.0 26.1 5.7 ** 1.0 6.1 4.5 6.4 **

Interincisal angle

()

125.8 18.3 132.7 9.5 * 133.1 8.5 121.7 20.4 ** 4.3 9.4 8.2 9.8 **

Extraction, n 40; nonextraction, n 40.

*P .05; **P .005.

Mand, mandibular; Max, maxillary.


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according to Steiner,21 the posttreatment mean in the

nonextraction group was excessive for the maxillary

and mandibular incisors. In the extraction group, the

mean posttreatment value was close to the normative

value for both the maxillary and mandibular incisors.For occlusal stability, Downs22 preferred an inter-

incisal angle of 135.4. The analysis of Steiner21

indicates an interincisal angle of 131. In this study, in

the extraction group, the inclination of the incisors was

reduced, and the distal movement of the incisal edges

was accompanied by a mean increase of the interincisal

angle of about 4.5, normalizing the interincisal angle.

In the nonextraction group, the proclination of the

incisors was more evident in the mandibular incisor

region. The increased inclination of the incisors was

combined with a forward movement of the incisal

edges and created a mean decrease of the interincisalangle of about 8 compared with a posttreatment value

of 121.

The ideal range for the nasolabial angles is defined

as between 90 and 120. In a study by De Smit and

Dermaut,23 the mean nasolabial angle for a mixed study

group was found to be 110. The mean value of the

nasolabial angle in the present study was at a relatively

high level, which increased with active treatment. The

nasolabial angle was increased in the extraction group

(4.8). The difference between the 2 groups was not

significant. These findings agreed with the results of

Finnoy et al,24

who found that their extraction grouphad a significantly greater increase of the nasolabial

angle than the nonextraction group.

The depth of the plica labiomentalis plays an

important role in the esthetic evaluation of the facial

profile. In a study concerning soft tissue profile prefer-

ence, De Smit and Dermaut23 reported that a flattening

of the mental fold led to a more drastic loss of esthetic

preference than a deepening. Considering the large

standard deviations, the changes during treatment

found in the present study have limited clinical impor-

tance.

Merrifields25

study of facial profiles in a sample of120 treated and untreated patients with pleasing facial

esthetics led to the development of the Z-angle to

quantify balance, or lack thereof, of the lower facial

profile. He found the normal Z-angle range in his

sample to be 72 to 83. In this study, the pretreatment

Z-angle of the extraction group was 67.5 compared

with 71.5 for the nonextraction group. In the extrac-

tion group, the posttreatment Z-angle became 69, an

increase of 1.5. In the nonextraction group, the Z-

angle remained the same (71.5).

The mean finished profile assessment for the extrac-

tion patients fell within the pleasing normal range, as

measured by the Holdaway26,27 H-line.

Soft tissue profiles were examined in 160 orthodon-

tic patients treated by removing the 4 first premolars by

Drobocky and Smith.10

The mean changes for the totalsample included an increase of 5.2 in the nasolabial

angle and retraction of the upper and lower lips of 3.4

and 3.6 mm to the E-line, respectively. When they

compared the profile changes to values representing

normal (or ideal) facial esthetics, it was evident that

extracting the 4 first premolars generally did not result

in a dished-in profile.10

The findings of the present study indicate that,

when a decrease of lip procumbency is desirable,

extracting premolars and retracting incisors is a viable

option to achieve these objectives. However, individual

variation in response is large. Incisor retraction in onepatient might lead to a large amount of lip retraction,

whereas, in another patient, a similar amount of retrac-

tion might lead to only minimal improvement in lip

procumbency. It would therefore be prudent to tell the

patient about the expected average change, but also that

it could be different in his or her particular instance. In

addition, when a 13- or 14-year-old patient presents for

treatment, and the main objective is to reduce the

prominence of the lips, the patients sex should be

considered. In an adolescent boy, the nose and chin will

continue to grow much more than in a girl. This will

have the effect of decreasing lip procumbency relative

to the SnPog line and especially to a line drawn from

the tip of the nose to the tip of the chin.

CONCLUSIONS

Measuring esthetics is very complex; in general,

after orthodontic treatment with 4 premolar extractions,

facial profile esthetics are improved, even if some

standards were not reached (nasal and chin changes)

because of remaining growth. Finally, the overall es-

thetic results of these relatively big changes on the

facial soft tissue profile are very difficult to measure

with numbers alone, and, to a certain degree, it is a

matter of subjective opinion, variable in nonextremecases from person to person, and even according to

modes, races, and social groups.

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4. Oliver BM. The influence of lip thickness and strain on upper lip

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Editors of the American Journal of Orthodontics and Dentofacial Orthopedics

1915 to 1931 Martin Dewey

1931 to 1968 H. C. Pollock

1968 to 1978 B. F. Dewel

1978 to 1985 Wayne G. Watson

1985 to 2000 Thomas M. Graber

2000 to present David L. Turpin


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