Over denture

The overdenture is a removable complete or partial denture prosthesis constructed over existing teeth, root structure and/or dental implants. The overdenture is also called overlay denture, overlay prosthesis or super imposed prosthesis.
Tooth supported over denture:
Overlay denture, overdenture, telescopes denture, and biologic denture are among the many terms used to define the tooth-supported complete denture.
Advantages of overdenture prosthesis:
1- Preserving the remaining residual ridge by decreasing the rate of bone resorption.
2-Preservation of the abutments as part of the residual ridge to gain support.
3- Preserving the response of proprioceptive exist in the periodontal membrane .
4- The modified teeth provide a definite vertical stop for the denture base.
5-Horizontal and torque forces are minimized.
6-Stability and support are increased.
7-Patient acceptance and Psychological Benefits.
8-A Simple Approach to the Problem Patient.
9-fewer post insertion problems
10- Convertibility& effective management .
11-Periodontal Maintenance.
12- Provide retention through the attachments.
Disadvantages of overdentures:
1. The susceptibility of the overlaid teeth to caries is high.
2. Periodontal disease of the retained teeth.
3. Bony undercuts of the alveolar ridge are often found adjacent to retained teeth
4. Encroachment beyond the denture space.
5. Overdenture construction is time consuming and expensive
Indications:
1-Few remaining teeth unsuitable for fixed or removable partial dentures.
2- Remaining teeth present with unhealthy periodontal condition.
3- Patients with class II or class III Angle s classification.
4- Patients presenting abnormal jaw size large maxillary or mandibular bone defects.
5- The construction of over-denture is an alternative line of treatment to single dentures opposing few natural teeth.
6- Patients presenting congenital defects as cleft palate, microdontia, amelogenesis or dentinogenesis imperfecta or partial anodontia.
7. Congenitally missing teeth.
Contraindications:
1-poor oral hygiene.
2-Interarch space inadequate to accept the denture and the abutments.
3-mentally and/or physically handicapped
4-periodontally involved remaining teeth
a-Class III mobility that is due to the loss of alveolar bone that cannot be corrected
b-Soft tissue and osseous defects
c-Inadequate zone of attached gingiva
d-Excessive reduction of the adjacent residual alveolar ridge as a result of elimination of osseous defects
e-Patients who will not keep the retained teeth free of plaque.
5-The contraindications for endodontic treatment for the remaining teeth:
A-Vertical fracture of the root or roots.
B- Mechanical perforation of the root.
C-Internal resorption that has perforated through the side of the root.
D-Broken instrument in the root canal.
E-Horizontal fracture of the root below the bony crest.
6-Time & economy.
Tooth supported overdenture can be classified according to the time expected to the denture to be worn, into:
1. Immediate overdenture
2. Transitional or intermediate overdenture
3. Definitive (Remote) overdenture
Use of the Overdenture Concept in Other Areas:
Congenital and Acquired Defects:
The OD application can afford a very workable and relatively simple solution to patients with selected problems .The important benefit is that the technique is totally reversible, such as cleft palate, microdontia, amelogenesis or dentinogenesis imperfecta or partial anodontia.
Partial Overdenture:
The use of an overlayed tooth that might otherwise be extracted to give posterior support to a distal extension base or to provide anterior support for a large anterior supply on a PD renders obvious support advantage .
Advantages:
-Preserve alveolar ridge.
-Possibly: support, proprioreception, retention, stress distribution.
Disadvantages:
• Poor oral hygiene, caries &periodontal disease.
• Soft tissue undercuts: effect the esthetics& retention.
• Breakage of denture: because it thin, stress concentration over abutments.
1-Simple Tooth Modification and Reduction
• teeth are merely reshaped to eliminate undercuts
• reduced in vertical height
Indication:
1-good oral hygiene with a low caries index
2-vital pulps must be receded sufficiently
3-partially anadontic patient
4-severe abrasion of teeth
5-sufficient interocclusal distance
2-Tooth Reduction and Cast Coping:
• minimum reduction in the crown: root ratio
• A cast coping are made after reducing the teeth to prevent sensitivity or as caries control
Indicated when the teeth have :
1 – Adequate bony support
2 – Good periodontal prognosis
3 – Adequate interocclusal distance