Overdentures

Question 1

Definition

Answer 1

Any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants;

Question 2

Indications

Answer 2

Few natural teeth remaining
Poor prognosis for routine complete denture
Congenital or acquired intra oral defects i.e. cleft palate
Rapid bone loss in mandibular arch
Edentulous arch opposing dentate arch

Question 3

Classification

Answer 3

1. Tooth supported
a) Non coping
b) Coping (long, short)
c) Attachments (stud, magnet, bar)

2.Implant supported
a) Tissue implant supported
b) Fully implant supported

Question 3

Advanatges of overdentures

Answer 3

1. Preserves remaining teeth
2. Preserves alveolar bone
3. Preserves proprioception
4. Improved support
5. Improved retention
6. High patient acceptance

Question 4

Disadvantages of overdentures

Answer 4

1. Carious breakdown ofabutment teeth
2. Limited interocclusal space
3. Bulkier than conventional dentures
4. Bony undercuts adacent to retained teeth
5. Success largely related to patient’s commitment to personal oral hygiene measures.
6. The rigid and frequent recall appointment protocol implies additional expense

Question 5

Factors that influence the selection of abutment teeth include

Answer 5

1. Periodontal status
2. Mobility
3. Location
4. Cost implications
5. Endodontic and prosthodontic considerations

Question 6

NON COPING ABUTMENTS

Answer 6

Selected tooth abutments are reduced to a coronal height of 2 to 3 mm. and then contoured to a convex or dome shaped surface.

Most teeth required endodontic therapy and in final step are prepared conservatively to receive an amalgam or composite type restoration.

Advantages
• Least expensive option
• More amenable to treatment, retreatment and modification in contingency situations
• Greater degree of flexibility in formulating treatment plan

Question 7

Abutments with coping

Answer 7

Coping is a cover for the exposed tooth surface

Cast metal coping with a dome shaped surface and a chamber finish line at the gingival margin are fabricated and cemented (short coping, long coping).

1. Short copings are 2-3 mm and normally require endodontic therapy because the required coronal root reduction would expose the pulp.
2. Long cast coping
   Long cast copings are normally 5-8 mm long, conservative reduction of coronal tooth structure is done.

> The end result is long ellipsoidal shaped coronal coping and a larger crown root ratio. They require more osseous support

Question 8

Abutments with attachment

Answer 8

Attachments are small precision devices.
• Objective is to improve retention of denture base. r Most attachments are secured to abutment by a cast coping.

Consists of two parts:
• Male
• Female

Requirements for the Attachments
- Patients should have a low caries index.
-Perform proper home care
-Sound periodontal health
-Proper bone support

Disadvantages of attachments
1. Added time
2. Expensive
3. Difficult to construct
4. Repair is difficult
“ Requires careful manipulation by the patient, not recommended for mentally and physically handicapped

Question 9

Rigid vs Resilient attachment

Answer 9

Rigid attachment
• Doesn’t allow movement of denture base
• Provide adequate retention
• May induce more torque on abutment

Resilient attachment
• Allows some control of movements
• Induces less torque on abutments

Answer 10

1. Stud attachment
   Simplest of all attachments consists of two parts
   • The stud (male component) usually attached to metal coping cemented over prepared abutment
   • Housing (female component) embedded in the fitting surface of over denture