OVERDENTURE.

DR

Hussein Abd El-Hady Hussein Taha

B.Ds., M.Sc., PH.D.

First and above all, thanks to merciful ALLAH, who enable me to complete this work.

Introduction

The drawbacks of conventional complete dentures can

be masked by the use of overdentures, which dictates the

preservation of tooth structure or placement of implants.

The overdenture is defined as; A complete or partial denture

that may be supported by soft tissue, bone, root of a tooth or

a modified tooth or dental implant.

The overdenture is also called overlay denture, overlay

prosthesis or super imposed prosthesis.

Tooth supported complete denture is a dental

prosthesis that replaces the lost or missing natural

teeth and associated structures of maxilla and/

mandible and receive partial support and stability from

one or more modified natural teeth.

The basic principles of overdenture are:

- Prevent resorption of alveolar bone

- Maintain sensory feedback

- Provide retention and stability

OBJECTIVES OF OVERDENTURE PROSTHESIS:

- Retaining the abutments as part of the residual ridge to

gain support and retention

- Preserving the remaining residual ridge by decreasing the

rate of bone resorption

- Preserving the response of proprioceptive exist in the

periodontal membrane of the abutment tooth.

PRINCIPLES TO BE OBSERVED IN

CONSTRUCTION OF OVERDENTURES:

1. Retained teeth should be reduced to obtain a favorable

crown root ratio.

2. To minimize the vertical movement of the denture, the

retained teeth should be used.

3. The overdenture should be partially tissue borne.

INDIATIONSCONTRA INDICATIONS

ADVANTAGES DISADVANTAGES

INDICATIONS:

1. Widely distributed teeth.

2. Few remaining teeth unsuitable for fixed or removable partial dentures.

3. Unhealthy periodontal condition.

4. Patients with class II or class III Angle's classification.

5. Abnormal jaw size ; large maxillary or mandibular bone defects.

6. Congenital defects as cleft palate, microdontia, amelogenesis or dentinogenesis

imperfecta or partial anodontia.

7. As an alternative line of treatment to single dentures opposing few natural teeth. to

prevent combination (Kellys’ syndrome )

CONTRAINDICATIONS:

1. Overdentures are contraindicated in case of poor oral hygiene.

2. Interarch space inadequate to accept the denture and the abutments.

3. Inadequate zone of attached gingiva with grade II mobility of the abutments.

4. Patients who cannot psychologically accept any type of removable denture

ADVANTAGES:

- Greatly Enhanced Stability: - Positive Retention:

- Proprioception: - Psychological Benefits:

- Post Extraction Comfort: The denture sore spots are greatly diminished

- Positive Support and Comfort:

- Reduce forces:

- Preservation of Aveolar Bone: through tensile stimulation of periodontal ligament.

DISADVANTAGES:

1. More expensive than conventional dentures because of periodontal and endodontic

therapy followed by restoration of abutment with coping.

2. Increased bulk in comparison with fixed and removable partial denture.

3. Progression of caries and periodontal disease if oral hygiene is not maintained

4. Encroachment of inter-occlusal distance. reservation of Aveolar Bone: through tensile

Classification

Overdentures can be classified into:

Tooth-supported overdenture Implant-supported overdenture.

Tooth supported overdenture

The tooth supported Overdentures improve stability

retention, masticatory performance, occlusal loading and help

to preserve vertical dimension and facial support.

Advantages of tooth supported overdenture prosthesis:

1. Preservation of the abutments as part of the residual ridge to gain support.

2. Preservation of the proprioception

3. Preservation of the remaining residual ridge

4. Increase patient acceptance by providing psychological benefits

5. Convertibility: overdentures can be converted into a conventional complete

denture after loss of the abutments and relining or rebasing of the denture.

6. Provide mechanical retention through the attachments.

Disadvantages of tooth supported overdentures:

1. Caries and periodontal break down of the abutments teeth

2. Inadequate reduction of the abutment teeth may increase vertical

dimension.

3. The bony undercuts adjacent to the abutment teeth (usually buccally)

cause limitation of path of insertion of the over denture.

4. Time consuming and expensive line of treatment compared to the

conventional complete denture.

5. Encroachment of the inter-occlusal distance leads to bad Esthetics.

Classification ofTooth supported overdenture

Immediate overdenture

Transitional or intermediate overdenture

Definitive (Remote) overdenture

According to the time expected to the denture to be worn

Immediate overdenture

patients with almost a full set of

teeth, most of which are to be lost.

The remaining teeth are reduced to

accept the overdenture (on the cast),

the overdenture is constructed prior

to the preparation of abutment teeth

and is inserted after the preparation.

Transitional Overdenture

Obtaining by Converting an already existing RPD to an O.D.

According to its design into:

1. Simple tooth reduction of vital tooth

2. Tooth reduction and cast coping of vital abutment (Thimble or dome- shaped)

3. Endodontic therapy and amalgam plug

4. Endodontic therapy with post and coping

5. Endodontic therapy with cast coping and attachments

6. Endodontic treated tooth with intra-radicular attachment

7. Telescopic Overdenture

1. Simple tooth reduction of vital tooth

The tooth is modified by reducing the buccal surface 30° and lingual surface 15°. The

mesial and the distal surface are modified to remove the undercuts.

2. Tooth reduction and cast coping of vital abutment (Thimble or dome- shaped)

A- The thimble-shaped coping: B- Tooth reduction and cast coping:

3. Endodontic therapy and amalgam plug

The crown needs severe reduction so endodontic therapy is necessary; the reduced

height is 1-2 mm above the gingival margin. The root canal is filled with gutta percha

and the opening is sealed with amalgam plug (Dome-shape appearance)

4. Endodontic therapy with post and coping

- The crown is reduced to the dome-shape and wax pattern is made for cast coping.

- The metal coping takes its retention from a short post inserted in the root canal

5. Endodontic therapy with cast coping and attachments

Clinically, two attachments are enough to retain a denture. A third attachment adds

unnecessary complexity and weakens the denture.

•The coping has an attachment above.

6. Endodontic treated tooth with intra-radicular attachment

The indication of this type is patients with good oral hygiene measures.

The abutments are prepared as in short-coping but with long intra-radicular post to

prevent root-coping dislodgment. No coping is used for this type.

7. Telescopic Overdenture

It have two types of coping; primary coping on the natural teeth and secondary coping

in the denture. Retention is generally obtained through the frictional resistance

produced between the semi-parallel walls of the two copings and tissue side of the

denture base.

CLINICAL PROCEDURES

I.Patient Selection

Possibility of a Fixed or Removable Partial Denture

Condition of the Abutment Teeth

Age of the Patient

I.Abutment Selection:

Position of abutments.

Number of abutments.

Periodontal evaluation.

Endodontic evaluation.

Decay or previous restorations.

I. Position of abutments

At least one tooth per quadrant.

Two teeth in each quadrant present an ideal situation in

which stress is distributed over a rectangular area.

Canines and premolars are the best overdenture

abutments to reduce adverse forces at this site.

It is recommended to use isolated teeth as abutments

rather than adjacent teeth because they are easier for

patient to maintain hygiene.

As the anterior alveolar ridge resorbs easily under stress, anterior teeth are not usually

selected.

I. Position of abutments

Maxillary incisors can be used as overdenture abutments, if the mandibular arch is

intact to prevent the destruction of the anterior maxillary ridge (kellys’ syndrome).

Periodontal evaluation.

Bone support, pocket depth, width of attached gingiva, mobility, furcation involvement, & root

morphology.

• Minimal mobility

• At least 6mm of bone support

• Attached gingiva around the abutments

• Good oral hygiene

• Proper emergence profile to support

the marginal gingiva

Endodontic evaluation.

Single rooted teeth are easer to treat.

Pulpal recession

The use of restorative materials and sealants

Prior RCT already done.

Potential for RCT

Restorative Condition

Caries.

Previous restorations.

Crown lengthening indicated.

Preparing the Abutments Size of the preparation

Preparing the Abutments

Shaping the preparation

Preparing the Abutments coping

Options

Leave it as is

Options

Make preparation with amalgam plug Put a coping on it

Implant supported overdenture

Implant supportedoverdenture

Implants are the latest trend in prosthodontics these days.

Implants are used as a part of removable and fixed partial dentures.

They play an important role in complete dentures too.

Some patients will not be able to wear their dentures

irrespective of its perfect contour. These patients are termed as

"Mal-adaptive". The implant-supported denture can be designed

for these patients.

Implant supportedoverdenture

Sincerely :

Dr. Hussein A. Hady Hussein