Acquired Maxillary Defects

Part 2

Definitive Obturator

Definition

A maxillofacial prosthesis that restore part

or all the maxilla and the associated teeth

lost due to surgery or trauma.

Constructed after complete healing by 3-4

months post surgically.

Construction

Primary impression:

Stock tray

modification with fast

set hydrocolloid is

used to make the

impression taking in

mind that the medial

undercut of the defect

should be blocked-out

with Vaseline gauze.

Secondary impression: Clean of defect side and the undercut area should be blocked by veslinized gauze.

Border molding was done starting with unresected side , followed by defect area bellow the skin graft-mucosal junction, then lateral, posterior and anterior above the scar band.

The impression was recorded by rubber impression material.

Master cast.

Secondary impression

Jaw relation: Occlusion blocks can be

fabricated and the Jaw

relation was recorded

Means of retention for Definitive

obturator 1. Clasping the remaining natural teeth.

2. Buccal retaining flange engage the teeth and tissue undercut in dentulous side.

3. Maximum extension.

4. Undercut in the defect side.

5. Implant in the intact side.

6. Magnet.

7. Two sectional obturator with two path of insertion.

8. Swing-lock in dentulous side.

9. Using scar band in the lateral wall of the defect.

10. Denture adhesives.

11. Hallowing the obturator.

Clasping the remaining natural

teeth

Swing-Lock Attachment

Buccal Retaining Flange

Extension to the defect undercut

Hallowing obturator

Open top obturator

Implant as means of retention for

the obturator Anterior

maxillary

segment

Zygoma

Classification of Maxillary defect

Aramany’s Classification

Aramany’s Classification

Class I: Lateral defect with anterior

margin approaching the defect.

Class II: Lateral defect with the anterior

margin away from the defect.

Aramany’s Classification

Class III:

Middle defect surrounded

by remaining teeth.

Class IV:

Lateral defect with

anterior margin crossing

the midline.

Class V:

Defect with anterior teeth

remaining.

Class VI:

Defect with posterior teeth

remaining.

Principles of RPD design

Major connectors must be rigid.

Occlusal rest must direct occlusal forces along the

long axis of the teeth.

Guide planes are employed to enhance stability and

bracing.

Retention must be within the limits of physiologic

tolerance of the periodontal ligament.

Maximum support is gained from the adjacent soft

tissue denture bearing surfaces.

Designs must consider the needs of cleansibility.

Maxillary Defects

Problems complicating RPD design

– Multiple axis of rotation

– Compromised support on the defect side

– Lack of cross arch stabilization because of

the loss of palatal structures on one side

– Long lever arms

– Forces of gravity become more significant

Movement of the prosthesis and the

length of the lever arm Potential exists for substantial movement as compared to the normal patients.

Length of lever arms are much greater than seen in conventional prosthodontics.

Clinical significance: There is greater risk of overloading abutment

teeth with inappropriate partial denture designs.

Preservation of teeth

RPD designs must anticipate and

accommodate the movements of the

prosthesis during function, without exerting

pathologic stresses on the abutment teeth.

Clinical significance: If the RPD designs do not conform

to this idea there is risk that abutment teeth may be

overloaded leading to their premature loss.

Multiple axis of rotation

Fulcrum line Fulcrum lines are dynamic and once the sites of

occlusal rests are selected, the axis of rotation is dependent upon the site of load application

Load #1 – Fulcrum

line A - B

Load #2 – Fulcrum

line C - D

Load #3 – Fulcrum

line E - F

Abutments adjacent to the defect

These teeth are subject to more vertical

and lateral forces and are more

frequently lost than abutments in other

positions. Why? The defect offers little support.

The long lever arms magnify the occlusal

forces

Clinical significance: Design and position of rests on these teeth must

direct forces along the long axis of the teeth. In some patients

splinting these teeth to adjacent teeth may be useful; in others it is best

to use these teeth as overdenture abutements.

Abutments adjacent to the defect

–Rest position and contour

These rests all have one factor in common – they permit

engagement of the tooth in a “positive” manner and

direct occlusal forces along the long axis of the tooth.

Rest position and contours – Incisal rests are contraindicated on teeth

adjacent to the defect. In this patient the incisal rest on the cuspid will disengage when an occlusal force is applied posteriorly

– This incisal rest is used for bracing

Rest position and contours

Anterior teeth adjacent to the defect must have “positive” cingulum rests.

Rest position and contours – Incisors – Splinting and cingulum rests. We recommend that

incisors adjacent to the defect be splinted together with full

veneer crowns and cingulum rests be developed within their

contours.

Note hygiene access

Rest position and contours – Bonded cingulum rests - Long term results

have been very disappointing.

Bolus manipulation – Patients soon learn to confine the bolus on the dentate

side but they will incise on the defect side. Therefore, in

most radical maxillectomy defects, clinically the most

significant axis of rotation will be similar to the C-D axis

seen in this defect. However, in this patient the A-B axis

is the most important.

Retainers “I” bars are almost always used on the

abutment tooth adjacent to the defect. Why?

•Maximum natural cleansing

action

•Passive functional

movement of an extension

prosthesis

•Better esthetics

•Minimal tooth contact

•Exact placement of retention

contact

•Minimal Interference with

natural tooth contour

Retainers “Suprabulge retainers are used posteriorly

Why?

•Better bracing and stability provided

by this type of retainer.

Stability and Bracing

– Lingual plate

– Suprabulge retainers

More bracing is

required in maxillary

resection defects and

so suprabulge

retainers are use on

posterior teeth and

lingual plating is

frequently employed.

Support - Palatal shelf area available

One of these patients had a favorable defect and ample palatal

shelf area. The other does not. Partial denture designs can be

conservative for the patient on the left. Little bracing is

required and fewer retainers are necessary. The opposite

would true for patient on the right - more retainers and more

bracing are required.

Master Impressions

Impressions for the RPD framework

– Stock tray with reversible hydrocolloid

Altered cast impressions of the defect

– Border molding with dental compound

– Wash impression materials

Elastic materials vs thermoplastic wax

Clinical procedures

Impression for the RPD framework

Physiologic adjustment of partial

denture framework

Altered cast impressions of the defect

Centric relation records

Trial dentures

Processing

Delivery and followup

Master Impresssions

Impressions for RPD frameworks A stock tray is used. Periphery wax is used to extend

the tray into the defect and onto the soft palate.

The completed impression

records the contours of

residual tissues, dentition,

and the defect

Undercuts on the

medial side of the

defect should be

blocked out.

Otherwise the

residual palatal

contours will be

distorted upon

remmoval of the tray.

Master cast and RPD framework

Verify and physiologically adjust

the RPD framework

Framework try-in appointment:

a) Verify accuracy of fit

b) Physiologically adjust framework

c) Occlusal adjustment of framework

Physiologic adjustment of RPD frameworks

Rouge and chloroform is still the most effective means. Guide planes and minor connectors should be carefully evaluated.

Silicone type indicators

are effective, but much

more expensive.

Note where the rouge has

been rubbed away from the

distal guide plane (arrow).

This area needs adjustment.

Physiologic adjustment of partial denture frameworks

Another framework. Note

the areas in need of

adjustment (arrows).

Adjustments are made with

a high speed air rotor.

Border molding

Altered cast impression tray

Border molding Mold the anterior segment first, followed by the

posterior segment. A compound with extended

working time is recommended.*

The patient is directed to make eccentric mandibular

movements to trim the posterior lateral portion of the

impression.

*GC Dental Industrial Corp. Chicago, Ill

Centric relation records

– Occlusal indices were

developed in dental

compound while making the

altered cast impression of

the defect and used to mount

the mandibular cast.

Wash impression materials

Polysulfide

–Used in smaller static defects

–Favored when large undercuts

need to be recorded

Completed impression.

Note that there is little

spillage of impression

material onto the major

connector.

Wash impression materials Polysulfide-Cut back and perforating the finish line

Border

molded

impression

Completed cut back.

Note the perforations

along the finish line.

These perforations

will ensure that the

RPD casting seats

properly when

making the wash

impression.

Making the corrected impression

Cut back the compound 1-2 mm and perforate the finish line.

Apply a thin

layer of

adhesive to the

border molded

impression up

to the finish line.

Inject the polysulfide

into the lateral

undercut before

inserting the border

molded impression

Polysulfide wash impression

Completed altered cast impressions of

radical maxillectomy defects and adjacent

tissues

Note that the minimal tissue

displacement of these impressions.

Wash impression materials

Thermoplastic wax – Preferred in larger defects

– Recommended when the

obturator extends into mobile

border tissues or into the

velopharyngeal area

Scar band

Master impressions Boxing the impression and making the

master casts

Centric relation records

Records can also be made with

conventional record bases

Occlusion

Occlusal scheme – Centric only contact on the defect side is preferred. The cuspid often

needs to raised or set to the labial. The buccal inclines of the buccal cusps need to be flattened and the buccal cusp tips shortened (a lingualized scheme of occlusion) .

Purpose of the prosthetic dentition on the defect side: a) Esthetic display

b) Lip support

c) Prevent opposing dentition from super-erupting

Processing and Finishing

The partial denture with obturator is flasked, and processed with heat polymerizing methyl methacrylate

The processed resin

is finished and

polished in the usual

fashion

Delivery steps

Pressure indicating paste

Disclosing wax

Clinical remount

Identifying Areas of Tissue Displacement

Pressure indicating paste – Useful for checking tissue displacement in the

defect when salivary flow is normal

– If patient suffers moderate to severe xerostomia disclosing wax is recommended

Delivery steps

Disclosing wax is preferred when checking the extension areas or mobile portions of the defect

Ramus imprint

Velopharyngeal

extension area

Completed RPD with Obturator

Speech and swallowing are restored to normal and mastication

can be accomplished effectively on the unresected side.

Esthetics in the anterior region

Use of attachments

This patient is status post partial palatectomy for a benign

tumor of the left hard palate. The left tuberosity remains and it

contains a third molar

Note the bracing arm through the proximal of #5 and #6. It is

non- retentive but keeps the RPD framework from being

displaced lingually in this region and with the cingulum rest on

#8, keeps the framework centered over the ERA attachment.

Esthetics in the anterior region

ERA attachment

Cingulum

rest

Bracing

arm Rest

Completed RPD

The two central incisors

have been splinted

together. A cingulum rest is

positioned on the mesial

side of #8. The ERA

attachment is incorporated

within the crown of #9.

High smile

Note the bracing arm.

Bracing arm

Completed RPD

Note the attachment associated with third molar. This serves as an occlusal

stop and has a retentive attachment incorporated within.

The ERA should not be used unless a positive occlusal stop is present on

the defect side, either from a tooth or an implant.

High smile

Thank U