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DR.NOOR ADDEEN ABO ARSHEED

Clinical Lecturer and Specialist Prosthodontist

Head of LUC Dental Center   BDS, HD Prostho, MDS , DOI (Germany) NBDE (USA) , FICOI (USA).

LINCOLN UNIVERSITY COLLEGE

Facebook.com/AboarsheedNasa

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OVERDENTURES Part 1

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introduction :

Occasionally, a patient with few remaining natural teeth may present himself at the clinics.

Most often they are advised total extraction and construction of conventional complete dentures.

However, it is possible to preserve these remaining teeth (after suitable treatment) and construct a denture over them.

Thus, the overdenture uses one or more modified natural teeth for retention, support and stability.

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Synonyms: These dentures have been called by a variety of names tooth supported dentures, overlay dentures, onlay dentures, overdentures, telescoped dentures, hybrid dentures, biologic dentures, coping prosthesis and superimposed dentures.

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RATIONALE 

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RATIONALE 

Why not extract all remaining teeth and plan a complete denture? 

The teeth and the alveolar bone are closely interlinked. Without the teeth, the alveolar bone tends to atrophy and resorb. The longer the teeth remain in the alveolar bone the longer it is preserved. Thus, it is important to preserve the alveolar bone for as long as possible.

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RATIONALE 

Thus, the overdenture is a logical method for use in preventive prosthodontics. Preserving the remaining natural teeth not only preserves the alveolar bone, but also gives the patient better function and control over the dentures because of the presence of nerve receptors in the root.

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RATIONALE 

Why not leave the remaining teeth and plan an RPD?

An RPD (removable partial denture) takes part of its support from the natural teeth. A large RPD utilizing a few remaining teeth for support and retention could result in excessive stresses on those teeth.

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RATIONALE 

Over a period of time mobility and periodontal breakdown could ensue resulting in failure of the abutments.

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RATIONALE 

Why shorten the teeth?

Shortening the natural tooth changes the crown root ratio This reduces the lateral stresses. It also reduces lever action on the tooth. The load is now in a more occlusal direction which is better tolerated by the tooth. The complete denture resting on these shortened teeth exerts largely vertical forces directed towards the bone which are better tolerated by the teeth.

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RATIONALE 

Reducing the crown ratio also forms the basis of using mobile teeth which would have been indicated for extraction. Reducing the crown-root ratio reduces the mobility of these teeth and improves their prognosis.

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DEFINITION

Any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants; a dental prosthesis that covers and is partially supported by natural teeth, natural tooth roots, and/or dental implants (GPT-8). 

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CLASSIFICATIONBased on method of abutment preparation:1. Non coping

With endodontic therapy

Without endodontic therapy 

2. Coping

With endodontic therapy (short coping)

Without endodontic therapy (long coping) 

3. Attachments

 

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CLASSIFICATION

 

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CLASSIFICATION

Based on type of overdenture 1. Immediate overdenture 

2. Transitional overdenture 

3. Remote overdenture

 

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CLASSIFICATION

Noncoping abutments with endodontic treatment 

Most teeth require endodontic therapy because of a lack of interocclusal space selected root abutments are reduced to a coronal height of 2 to 3 mm and then contoured to a convex or dome shaped surface. The root canal access opening is restored with amalgam or composite.

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CLASSIFICATION

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CLASSIFICATION

Noncoping abutments without endodontic treatment 

This type is given only if there is sufficient interocclusal space

The pulp should have receded sufficiently so that the reduced teeth are not sensitive

It is usually indicated in patients with partial anodontia and severe attrition .

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CLASSIFICATION

Coping abutments 

A coping is a thin covering. The abutment teeth may be covered with copings to give better protection against caries.

Cast metal copings with dome shaped surfaces and chamfer finish lines at the gingival margins are made and cemented.

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CLASSIFICATION

short cast copings  

These are 2 to 3 mm long and normally require endodontic treatment because of the risk of pulp exposure. The coping is attached by means of a post in the root canal.

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CLASSIFICATION

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CLASSIFICATION

Long cast copings

These are about 5 to 8 mm long and are given in an attempt to avoid endodontic treatment. They also require greater bone support.

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CLASSIFICATION

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CLASSIFICATION

Abutments with retentive devices 

In cases where increased retention is required for the denture, special retentive devices may be attached to the abutment and to the inner surface of the denture.

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CLASSIFICATION

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CLASSIFICATION

Immediate, transitional and remote overdentures 

The immediate overdenture is constructed for insertion immediately after extraction of some natural teeth. 

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CLASSIFICATION

A transitional overdenture is obtained by converting an existing removable partial denture into an overdenture.

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CLASSIFICATION

The remote overdenture is constructed after the extraction of the teeth, endodontic therapy, cast copings or any other procedure.

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INDICATIONS FOR OVERDENTURES 

1 . Patients with poor prognosis for routine complete dentures. • High palatal vault • Xerostomia. • Poor mandibular ridges • When high rate of resorption is expected • When opposing natural teeth are present  • Smaller dental arches

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INDICATIONS FOR OVERDENTURES 

2. Patients with congenital or acquired intraoral defects. • Partial anodontia• Microdontia.• Amelogenesis imperfecta

3. In case of severe attrition, vertical height can be restored with an overdenture. 4. Very young patients facing total extraction. 5. Low caries index and good oral hygiene

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INDICATIONS FOR OVERDENTURES 

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CONTRAINDICATION

1. High caries index and poor oral hygiene 2. When the abutments have a doubtful prognosis • When endodontic treatment is not possible • When periodontal therapy and reduction of crown-root

ratio does not improve periodontal health 3. Uncooperative, terminally ill, or senile patients.

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ADVANTAGES 

1. Preservation of the alveolar bone. Presence of the abutment teeth reduce resorption. 2. Preservation of the proprioception. Oral function and feeling is improved because of the proprioceptive feedback from receptors in the root. 3. Improved support because of the abutment teeth. 

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ADVANTAGES 

4. Improved retention. Retention devices can be attached to the abutment teeth when increased retention is needed 

5. Less psychological trauma as patients are able to retain their original teeth

6. Can be converted to a routine complete denture in case of abutment failure

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DISADVANTAGES 

1. High risk of caries especially for the noncoping abutments due to coverage of the teeth by the denture .

2. Risk of periodontal problems due to improper care by the patient 

3. High initial cost due to the castings, precision attachments, preceding endodontics, periodontal and other therapies. 

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DISADVANTAGES 

4. Long bony undercuts are often found near the abutment teeth. So tissue injury may result in ,during insertion and removal of the overdenture.

5. Tooth arrangement is difficult in some cases because of the reduced interocclusal distance. 

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THE ENDTHANK YOU FOR WATCHING