Treatment of distal edentulism

Treatment of distal edentulism

In the face of distal edentulism, the only therapeutic option is a partial prosthesis. Therefore, PPAC is still relevant.

Definition of distal teeth

Class I : bilateral posterior edentulism

Class II : unilateral posterior edentulism

Class I mod 1 : Bilateral distal edentulism complicated by embedded edentulism at the level of the residual arch

Class II mod 1 : Unilateral distal edentulism complicated by embedded edentulism on the other side

2. Problems caused by distal edentulism

Unlike a joint prosthesis where the support is purely dental, in the case of posterior edentulousness the support is mixed, which means that the removable prosthesis involves 2 types of tissue, hence the problem of tissue duality.

4.1. Tissue duality: It is the difference in tissue compressibility between the tooth and the mucosa, these are 2 tissues which react to pressure in very different ways.

• When the pressure ceases, the mucosa returns to its resting position but much more slowly than the dental support àvisco-elastic behavior of the fibro-mucosal support.

Treatment of distal edentulism

4.2. Moving the saddles in extension:

Due to the absence of the posterior tooth, the saddles are subjected to 6 TABET movements: 3 MVTS TRANSLATION + 3 MVTS ROTATION

Vertical translation – Horizontal translation – Mesio-distal (or disto-mesial) translation.

Vertical distortion rotation – Rotation around the ridge axis – Rotation in the horizontal plane

Which will need to be countered by a judicious design of the metal chassis.

Therapeutic proposals of a typical chassis

                  * Class I superior

• Main connection : solid plate
• Hooks : 2 Nally Martinet on the 2 teeth bordering the edentulous area

              – a mesial occlusal support, this reduces the risk of distal version

              – a mesial stem allows free play of the saddle, for axial transmission of forces on the crests independently of the teeth

• 2 retention grids , located in front of the tuberosities.
• Indirect occlusal supports : Indirect cleats, cingulate bar, coronal bar.

* Lower Class I

• Main connection : lingual bar whenever the internal table allows it, otherwise it is a lingual strip.
• Hooks : Nally Martinet on 2 support teeth
• Indirect occlusal supports with a mesial bracket are essential

*Class I mod 1

Treat the embedded edentulism with a fixed prosthesis preferably.

          and in 2nd stage: treatment of distal edentulism by metal frame: same outline for class I

Otherwise treat entirely by PPAC: Addition of a saddle previously

*Class II superior

• Main connection : full palatal plate
• Hooks: on the edentulous side àNally Martinet with mesial bracket

          On the Bonwill toothed side àto balance the saddle, placed on the 1st and 2nd molar for aesthetic reasons.

• Indirect occlusal supports on the edentulous side and/or on the toothed side

*Class II lower

• Main connection: bar or lingual strip
• Hooks: on the toothless side àNally Martinet

          On the Bonwill toothed side àlocated between PM and 1st M (this corresponds to the center of the opposite saddle)

• Direct occlusal supports : essential on the edentulous side with mesial bracket

*Class II mod 1

Distal edentulism: class II outline

Intercalated edentulism: 2 Ackers hooks bordering the edentulism with a retention grid.              

Dissociated footprint

          The aim of the split impression technique is to reduce the effects of the difference in tissue depressibility by making a compressive impression of the edentulous sector under conditions approaching functional loads.

Treatment of distal edentulism

The procedure is as follows:

• Production of a saddle for holding an impression in self-adhesive resin, covering the retention grids according to a PEI outline.
• With hard wax beads.
• Mouth adjustment of the resin saddle in static and dynamic mode
• Recording the situation of the edge of the saddles carrying impressions
• Taking the impression with a medium viscosity silicone with stress on the peripheral structures, without exerting digital pressure on the stools.
• Recording of intermaxillary relationships: with adjustment of the occlusion rims.
• Record the impression under occlusal pressure with a low viscosity material, shaping the edges of the impression with functional movements.
• Splitting the model, Cutting the terminal ridge
• Formwork and Casting of the Imprint: Corrected Model Technique

Occlusion recording

At the same time as the recording of the dissociated fingerprint.

Transfer to semi-adaptable articulator

Assembly and mouth test

Same PTA assembly rules:

          – respect of Pound’s area for the mandible

          – assembly outside the crest of the upper anterior sector.

          -respect of the rules of Ackermann’s 3H (heterotopia, heteromorphy, heteronumber)

Post-prosthetic treatment

• The patient should be reviewed after delivery of the prosthesis, hard and soft tissues should be examined.
• Motivation for hygiene
• Periodic checks with rebasing of the stools are necessary.

Conclusion

The treatment of distal edentulousness is one of the most complex clinical realities to treat; only rigorous compliance with all the design conditions allows for a lasting tissue and prosthetic balance to be achieved over time.

Treatment of distal edentulism