Clinical Procedures In Overdenture

Define Overdenture And Discuss In Detail The Clinical Procedures In Overdenture.
Answer:

Overdenture Definition

A tooth-supported complete denture is a dental prosthesis that replaces the lost or missing natural dentition and associated structures of the maxillae or mandible and receives partial support and stability from one or more modified natural teeth.

Overdenture Other Techniques

Other techniques for the preparation of teeth to serve as abutments for overdenture include simple tooth modification and reduction, tooth reduction, and cast coping, endodontic therapy with amalgam plug, endodontic therapy and cast coping and endodontic therapy and cast coping utilizing some form of attachment.

Read And Learn More: Complete Dentures Question and Answers

Overdenture Clinical Procedure

1. Remove the hopeless teeth and insert the removable prosthesis.
2. During the healing period, periodontic and endodontic treatment is carried out and the clinical crowns of the retained teeth may be reduced at this time.
3. Preparation of retained teeth.

Overdenture Tooth preparation is of two types

1. For minimal retention utilize only the clinical crowns.
2. For positive retention use endodontically treated root.

Overdenture Tooth Preparation for Minimal Retention

1. Sufficient tooth structure is removed to provide a favorable crown-root ratio, acceptable esthetic position for prosthesis, and a favorable occlusal relation with the opposing arch.
2. The prepared tooth is tapered in an occlusogingival direction with a chamfer margin extending beneath the free gingival margin.
3. The finished tooth with attached coping is the male member of the denture. The female member is a part of the denture base
4. The occlusal and/or incisal surface is prepared to accommodate a cobalt chromium bearing.
5. Coping fabrication: Carve the wax pattern on the die made from an accurate impression placing the concavity in the occlusal surface of the pattern, using a wax tool. Cast the coping, using a hard type of Class 3 gold. Cement the polished coping to the tooth.

Overdenture Steps in Clinical Procedure

1. Preliminary impression with alginate, cast is poured in dental stone and a custom-made impression tray is made by applying one thickness of baseplate wax (1 to 2 mm) over the abutment teeth.
2. The final impression is made using Elastomeric impression material. A master cast is obtained on which record Bases and Occlusion Rims are made with the incorporation of the metal bearing in the record base.
   • This is done by adapting one thickness of baseplate wax to the abutments, leaving the occlusal surface exposed. The bearing is seated in the concavity and sealed in place with wax over which a stable record base is made.
3. Jaw relation is made in the same manner as conventional complete dentures.
4. Teeth arrangement
   • Acrylic resin artificial teeth are used commonly, but if the opposing arch tooth is gold or porcelain then the same material is preferred for replacement.
   • The metal bearing is retrieved after removing the record base and repositioned in the concavity. The acrylic resin tooth is made hollow with an acrylic bur until the metal bearing is properly positioned.
   • Occlusion is adjusted, after the bearing is positioned to the acrylic resin tooth with sticky wax, and the rest of the teeth are arranged in maximum occlusion.
5. At trying-in:
   1. Verify the centric and eccentric jaw relation records.
   2. Assure esthetic and phonetic acceptability by the patient.
6. Laboratory Procedures
   1. Contour the wax.
   2. Flask the denture.
   3. Eliminate the wax.
      • The metal bearings are retrieved from the acrylic resin tooth, cleaned with boiling water, dried and the metal bearing is seated in the concavity and a coping of activated acrylic resin is made, using the “shake on” technique.
      • This allows trial packing of the heat-cured acrylic resin denture base. Remount procedures for processing errors are completed.
7. Denture insertion
   1. • Using pressure-disclosing paste, the contacts between the female member in the denture base and the male abutments are assessed.
      • There should be no contact except between the convex surface of the metal bearing and the concave bearing surface of the coping.
      • After evaluating the tissue side and the borders for pressure areas and overextension, remount procedures are completed to perfect the occlusion. The patient is recalled once a month for the first six months and once every three months thereafter.
8. Tooth preparation to provide retention

• In positive retention, the attachment used is the endodontically treated root of the tooth and not the clinical crown.

1. 1. The clinical crown is prepared to the level of the gingiva.
   2. A root cap preparation is made after opening the root canal to the desired diameter and depth for retention and rigidity.
   3. An individual impression of the root preparation and canal is made, the stone is poured, and die is prepared.
   4. A dowel is fitted with an acrylic knob attached to the canal in the die. Hence, the knob is securely embedded in the irreversible hydrocolloid impression and also used to position the die accurately for cast pouring.
   5. A full arch impression is made of Alginate.
   6. The dies are fitted to the transfer dowels and the impression is poured in dental stone.
   7. Remount indices are placed in the base of the cast.
   8. The die is covered with one thickness of baseplate wax before making a record base.
   9. Jaw relation records are made and the casts are mounted onto the articulator.
   10. The male member is placed as close to the center of the root as possible sometimes in a slight lingual position if more favorable for the esthetic positioning of the artificial tooth.
   11. The cap, post, and male member are waxed and invested in a flask, and cast in a hard gold alloy.
   12. Teeth are arranged, try in done, Waxed up and a denture is processed.
   13. The cast is retrieved and remounted to correct processing errors.

Overdenture Endodontic Therapy with Cast Coping Utilizing Some Form of Attachments

Endodontic therapy is used in situations in which stability and retention are desired. This requires sufficient interridge distance.

Overdenture Attachments used are

1. Stud attachments
2. Gerber attachment
3. Dalbo attachments: rigid, resilient, and stress broken
4. Ceka attachment
5. Ancrofix system
6. Magnets as cobalt-samarium
7. Bar attachments of two types: Bar units and bar joints. Examples: Hader bar, Dolder bar, and the Dolder bar joint. Clips as Baker clip, Ackermann clip, and CM clip.
8. Quinlivan attachment.

• • Photoelastic tests concluded that the best design for uniform distribution of occlusal forces was the conventional amalgam plug design.
  • If more retention and stability are required then other designs such as the stud attachment, the Ancrofix, and the Hader bar, transferred stress in a more favorable manner than other types tested.
  • Common failures in overdentures were related to poor case selection and inadequate maintenance. If proper patient selection, patient motivation, basic prosthodontic principles, home-care instruction, and frequent recall are done then the success of overdenture is high.
  • Floss, periodontal aids, small brushes, and rubber tips, must be utilized to minimize all plaque accumulation from the tooth surface and sulcus for the long life of the overdenture prosthesis