Prof. Dr. Ahlam El-Sharkawy Pharos University in Alexandria

Introduction

Extraction of teeth followed by continuous ridge resorption & poor denture foundation

Loss of periodontal receptors responsible for proper masticatory function & accurate jaw movements

Retention of few remaining teeth to support denture will preserve alveolar bone & preserve periodontal receptors

Definition of overdentures Complete or partial denture constructed over existing

teeth, roots or implants for providing additional support, stability & retention

Called also:

Overlay denture

Overlay prosthesis

Superimposed prosthesis

Types 0f over-Dentures. -Tooth supported over-dentures.

- Implant supported over- denture.

Prof. Dr. Ahlam

El-Sharkawy

Indications 1. Cases having few hopeless teeth unsuitable as

abutments for fixed or removable bridges

2. Patient having few remaining teeth with periodontal disease.

3. Patient with abnormal jaw size or position

4. Patient with congenital or acquired defects as cleft palate ,dentinogenesis imperfecta

5. Patient with single denture

6. Patient exhibit flat ridges

Contra-indications 1. Mentally or physically handicapped

2. Patient can’t be motivated to develop good oral hygiene

3. Inadequate intermaxillary space

4. Teeth with grade III mobility or insufficient zone of attached gingiva

1- submerged roots Abutments roots are endodontically treated .

Reduced in height to a level below gingival margin

2- dome shaped abutment with amalgam plug mmmmmm

Abutments reduced to be 1-2 mm above gingival margin to reduce lateral force & torque

Endodontic treatment is necessary

The root canal is filled with gutta percha

The opening is sealed with amalgam plug.

The abutment is contoured to attain dome- shape.

Used in patient with low caries index &good oral hygien.

3- dome shaped abutments with cast copings

Abutment are endodontically treated & reduced to 1-2 mm above gingival margin

Metal dome shaped cast coping constructed to cover abutment

The metal coping has a short post cemented into root canal to retain the coping

4- abutments with telescopic crowns

Abutment teeth are either vital or endodontically treated & contoured to tapered configuration

Tapered metal copings constructed &cemented over abutments

Denture constructed with metal crowns having veneered facings

5- abutments with slight tooth reduction & cast copings Abutments are minimally reduced

With or without endo treatment

Covered with cast metal coping “long coping abutment”. This type is rarely followed because it

requires adequate ridge space

Endodontically treated, reduced & covered with metal coping

Coping has a long post to help retention

Attachment added either by soldering or during wax pattern

6- abutments with an added form of attachment

Types of tooth supported Over-dentures 1. Immediate over-denture

2. Interim over-denture

3. Definitive over-denture

4. Attachment retained over-denture

Immediate overdenture Constructed prior to preparation of abutment teeth &

ready for insertion after preparation& reduction

It enhances patient’s ability & adaptability to wear dentures

Interim overdenture Used for patients in transition or preparation phase

until permanent overdenture constructed

Patient old partial denture can be modified & used by extending the denture & add new artificial teeth using self cure acrylic resin

Definitive over-denture Conventional complete over-denture constructed over

1 or more abutment teeth

Could be made entirely of acrylic resin or in conjunction with metal bases

Attachment retained over-denture Constructed with an incorporated attachment to

improve retention

More expensive & more time for construction

Indicated for patient with good oral hygiene & low caries index

The abutment teeth should have good periodontal condition & adequate bone support

Types of Attachments a) Rigid attachment

Doesn’t allow movement of denture base

Provide adequate retention

May induce more torque on abutment

b) Resilient attachment

Allows some control of movements.

Induces less torque on abutments.

Over-Denture Attachment could be in the form of:

1- Stud Attachments.

2- Bar attachments.

3 Magnetic Attachments.

1- Stud attachment Consists of 2 parts

The stud usually attached to metal coping cemented over prepared abutment

Housing embedded in the fitting surface of overdenture

1- Stud attachment Extra-Radicular : The stud is attached to the metal

coping cemented over the prepared abutment, while the housing is embedded in the fitting surface of the denture. e.g : Ceka , Rotherman, Gerber

1- Stud attachment B- Intra-Radicular: The stud is attached to the fitting

surface of the denture and the housing is incorporated in the abutment. e.g : Zest Anchor

eg

2-Bar attachment A bar contoured to connect abutment teeth together ,

run parallel & overlie residual ridge

Provide support & retention for overdenture & splint abutment teeth

Bars may be in form of preformed metal or plastic

A- Bar units Rigidly fixed to copings, don’t allow any movement

between bar & sleeve

Transmits occlusal stresses totally to abutments “tooth born”

B- Bar joints Resilient attachments allowing movement between

bar & sleeve

Support provided by both residual ridge & abutment teeth “tooth tissue born”

3- magnetic attachments Small, strong mini magnets

One of poles cemented in a prepared cavity in endodontically treated abutment & the other attached to denture base