Repairing, Relining, Rebasing in a Complete Denture

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Introduction

An ill-fitting complete denture may cause various lesions on mucosa and inflammatory overgrowth could appear, so, reparing, relining or rebasing the denture will certainly resolve the problem.

Repairing

Denture may fracture during the function, or may drop on a hard surface. So the key of repairing is the accurate reassembling and alignment of the broken parts in their original position.





Midline Fracture

Causes

– No or insufficient relief in the midline.2
– Ridge resorption wit loss of relief effect.

Procedure

– Broken parts are assembled and fixed together with sticky wax on the polished surface.
– Assembled parts may be strengthened with burs or plastic sticks.
– Any undercut on the fitting surface is blocked out with wax or clay.
– Stone plaster is poured into the fitting surface. After stone setting the denture is removed from the cast and cleaned from any traces of sticky wax.
– Fractured edges are reduced, widened (8-10mm) along the fracture line and beveled towards the polished surface to increase bonding surface area.
– Dove tail cuts may be made to strengthen the repair joint.
– The cast is painted with separating medium and the denture is secured to the cast with rubber bands.
– Self cure is applied to the modified fracture area until the area is overfilled.
– Relief of the median palate raphea.
– Reline if needed.
– Remake in some cases.

Any Part Fracture

Main causes

Falling on the ground or the sink during cleaning.

Types

– Fracture with no missing part (repaired as mentioned)
– Fracture with missing or lost part.

Procedure

– An impression is made with the denture placed in patient mouth.
– After pouring the cast; either self cure is applied to replace the missing part, or wax is added and carved to resemble the broken denture part followed by flashing, packing, curing, finishing and polishing.



Fig 7: Mean Classical value changes from baseline to 10 days for Control and Test sites of 20 teeth.

Fracture with broken or missing teeth

Procedure

– Fractured teeth are cut away with burs.
– On the lingual side; enough acrylic is removed and dove tailed.
– Teeth of same shape; size and shade are positioned in proper alignment and waxed with base plate wax.
– A plaster index (key) is made to record and secure the position of waxed teeth.
– Tooth to be repaired are removed together with all wax around them.
– Teeth are then put back exactly in their original position aided by a plaster key.
– Self cure acrylic resin is added from the lingual side until repair area is over buit. It is then covered with tin foil.
– After curing; the index is removed and the denture is finished and polished.



Relining of complete denture

Definition

Resurfacing or correction of denture adaptation to underlying tissues by the addition of a new resin material to its fitting surface without changing its occlusal relation. Addition of material to the tissue side of a denture to improve its adaptation to the supporting mucosa.


Indication

Whenever the denture loses or has poor adaptation to the underlying tissues, while all other factors as occlusion; esthetics; centric relation; v.d.o and denture base material are satisfactory:

– Loss of retention.
– Instability.
– Food under denture.
– Abused mucosa.

General consideration

– Optimal tissue health.
– Reasonable R.C/C.O.
– Adequate peripheral extensions.

Procedures

Patient is instructed to leave his denture out of his mouth at least 48 hours to allow for recovery of tissues and reduce irritation caused by ill-fitted denture.

Denture preparation

– Any undercuts are removed from the denture base.
– Peripheral extensions are checked and adjusted.
– Borders are reduced and squared to provide a definite edge for addition of new resin material.
– A hole is made in the palatal surface to allow escape of excess impression material.
– Border tracing and new impressions are made under centric occlusion to maintain occlusal relationship.
– The denture with impression material is boxed and poured into stone.
– The denture is flasked and the old resin material is thoroughly cleaned and roughened.
– New resin acrylic material is packed and the denture is cured in pressure curing unit containing water at 45°C for 20 min. To prevent porosity of new resin material and wrapage of new resin material (release of internal stresses).
– Finishing and polishing is done in the usual manner.

Rebasing

Definition

It’s a process of readaptation of a denture to the underlining tissues by replacing the denture base material with a new one without changing its occlusal relation.

Indications

When the existing denture base is unsatisfactory; crazed or porous.

Procedure

– An impression is made with the denture and a cast is obtained.
– An occlusal and incisal index of the teeth is made in plaster using HOOPER DUPLICATOR, the posts of the lower part of the duplicator are seated in the upper part to maintain the relationship of the casts to the plaster index.
– The denture with the impression material are removed from the cast.
– Artificial plastic teeth are sectioned from the denture and all base material around the teeth is removed (porcelain teeth are removed by flaming).
– Teeth are placed and held in position in the index using sticky wax on the labial and buccal surface.
– A layer of base plate wax is placed over the ridge of the cast.
– The upper part of the duplicator is closed and denture teeth are waxed to the proper thickness and counter to the cast.
– The cast is removed; flasked and processed in the usual manner.
– After deflasking, the cast is reattached to the upper part of the duplicator to adjust any occlusal errors.
– Occlusion of rebased denture is further perfected by clinical remount.









References

– Clinic Manual 2003-2004; The Ohio State University Department of Primary Care
– Boucher’s Prosthodontic Treatment for E dentulous Patients, 11th Edition; Zarb et al., 2004
– Contemporary Fixed Prosthodontics, Rosenstiel et al., 2001
– Complex Denture Fabrication, M. van Putten, 2000
– RG Craig, Review of Impression Materials, Advance in Dental Research, Aug 1988, 2,51-64.

by Dr. Jaouadi Jamila


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