6during function dropped on hard Dentures may fractureduring function dropped on hardsurfaceKey of repair = accurate reassembling & alignment of the broken parts in their original position.
7Classification of fractured dentures I) According to location of fractureMidline fracture Any part fracture
8II) According to extent of fracture Without broken ormissing part &/orteethWith broken ormissing part &/orteeth
9III) According to timing of fracture Early fracture Delayed fractureIV) According to cause of fractureOperator Patient
10(mainly in maxillary dentures) Midline fracture(mainly in maxillary dentures)Causes:1) No or insufficient relief in the midline. (M.P.R.) (Early fracture)2) Ridge resorption with loss of relief effect. (Delayed fracture)
11Procedures for repair of midline fracture: Broken parts are assembled & fixed together with sticky wax on the polished surface.Assembled parts may be strengthened with burs or plastic sticks.
12Procedures for repair of midline fracture: Any undercut on the fitting surface is blocked out with wax or clay.The fitting surface is painted with separating medium.
13Stone plaster is poured into the fitting surface 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 (8-10 mm) 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.
14The cast is painted with separating medium and the denture is secured to the cast with rubber bands. Self cure A.R. is applied to the modified fracture area until the area is overfilled.N.B. An alternate method is to wax and contour the fracture line to the desired form using base plate wax, followed by flasking, wax elimination, packing with self cure A.R. and placing in the flask under press for 2 hrs.Deflasking, finishing and polishing is then done in the usual manner.
15Relief of the median palatine raphea. Reline if needed.Remake in some cases.
16Any part fractureMain cause is falling on the ground or the sink during cleaning.Types:I- Fracture with no missing partRepaired as mentioned.
17II- Fracture with missing or lost part Procedures:An impression is made with the denture placed in patient mouth.After pouring the cast, either self cure A.R. is applied to replace the missing part, or wax is added and carved to resemble the broken denture part, followed by flasking, packing, curing, finishing & polishing.
18III- Fracture with broken or missing teeth Procedures:Fractured teeth are cut away with burs.On the lingual side, enough acrylic is removed and dove tailed.Teeth of same size, shape & shade are positioned in proper alignment and waxed with base plate wax.
19A plaster index (key) is made to record & secure the position of waxed teeth. Teeth to be repaired are removed together with all wax around them.Teeth are then put back exactly in their original position aided by plaster key.Self cure acrylic resin is added from the lingual side until repair area is over built. It is then covered with tin foil.After curing, the index is removed and the denture is finished and polished.
20Relining of Complete Dentures Def: 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.
21Reline Indications Loss of retention Instability Food under denture 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 retentionInstabilityFood under dentureAbused mucosa
23Procedures:Patient is instructed to leave his denture out of his mouth at least 48 hrs 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.
24A hole is made in the palatal surface to allow escape of excess impression material. Slight reduction in the fitting surface may be done to create some space for the impression material.Border tracing & new impressions are made under centric occlusion to maintain occlusal relationship.The denture with impression material is boxed and poured into stone.
25. The denture is flasked, and the old resin material is thoroughly cleaned and roughened.
26. New acrylic resin 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 warpage of the old resin material (release of internal stresses).. Finishing and polishing is done in the usual manner.
27N.B.When both upper and lower dentures need relining, lower denture should be completed first. The upper may be relined against a stable lower denture.The denture should be clinically remounted to perfect the occlusion.
34Diagnosis-Occlusal disharmony Loss of stability and retentionIrritation and inflammation on one sideTeeth stained on one side
35Reline Contraindications Worn out denturesVertical dimension loss greater than 7 mmSignificant mucosal inflammationPoor denture estheticsDenture related speech problems
36Contraindications Severe tooth wear Severe vertical overlap with tooth wear (posterior tooth concept)Severe occlusal wear (CD evaluation)
37Pre-requisites for relining Recognition of abused tissues, with superimposed candidiasis.
38Initiate Tissue Recovery Program Intermittent hot and cold rinsesMassage tissuesRelieve pressure areasCorrect faulty occlusions and denture bordersMinimize stress bySoft dietRemoval of denture at nightUse tissue conditioners
62Rebasing of Complete Dentures Def: It is a process of readaptation of a denture to the underlying tissues by replacing the denture base material with a new one without changing its occlusal relation.Indications:When the existing denture base is unsatisfactory e.g. stained, crazed or porous.
63Procedures: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.
64The 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.
65The upper part of the duplicator is closed and denture teeth are waxed to the proper thickness and contour 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.