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Types of refitting procedures

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Clinical Removable Prosthodontics

Clinical Removable Prosthodontics
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    Types of  refitting procedures Types of refitting procedures Document Transcript

    • Types of Refitting procedures : 1. Reline, resurfacing tissue side of the denture with ,gnew base material 2. Rebase, refitting of denture by complete replacement of the denture base material without changing occlusal relations of teeth 3. Reconstruction, the denture is reassembled using original framework with new teeth & new base material RELINING is the resurfacing of a denture base with a new material to make it fit the underlying tissues more accurately REBASING is the replacement of a denture base with new material without changing occlusal relation of the teeth. The critical step in reline procedure is the maintenance of tooth framework relation during the set of impression. HOW TO DIAGNOSE DENTURES THAT NEED RELINING ? In Distal-Extension Saddles : Apply a seating force on the extreme distal end of the denture base & to see if anterior indirect retainer lifts off its rest preparation as the denture rotates around a fulcrum line In Bounded saddles : Tissue changes beneath these bases did not affect RPD support, and so relining is done for the following 1. unhygienic condition ( as trapping debris between RBD & RR 2. unsightly condition due to the space 3 pt discomfort 3. pt. associated with lack of tissue contact RELINING AND REBASING RPDs Types of Refitting procedures : 1. Reline, resurfacing tissue side of the denture with , g new base material 2. Rebase, refitting of denture by complete replacement of the denture base material without changing occlusal relations of teeth RELINING is the resurfacing of a denture base with a new material to make it fit the underlying tissues more accurately REBASING is the replacement of a denture base with new p material without changing occlusal relation of the teeth. In either case, a new impression is needed, using the existingdenture as an impression base for either a closed-mouth or an open-mouth impression The critical step in reline procedure is the maintenance of tooth framework relation during the set of impression HOW TO DIAGNOSE DENTURES THAT NEED RELINING ? In Distal-Extension Saddles : Apply a seating force on the extreme distal end of the denture base & to see if anterior indirect retainer lifts off its rest preparation as the denture rotates around a fulcrum line In Bounded saddles :
    • Tissue changes beneath these bases did not affect RPD support, and so relining is done for the following 1. unhygienic condition ( as trapping debris between RBD & RR 2. unsightly condition due to the space 3 pt discomfort 3. pt. associated with lack of tissue contact Indications of relining distal extension RPD : 1. Loss of occlusal contact 2. Loss of tissue support that causes rotation of RPD base when alternating finger pressure is applied on either side of fulcrum Need for relining is assessed by visual examination of the loss of support from supporting tissues 1 Using thin mix of alginate. 2. Using finger pressure: applied to retromolar pad area of distal extension retainer 1 RPD base , if indirect lifts 1- 2mm from its rest preparation A thin mix of alginate ( minimum tissue displacement) used to evaluate the RPD base fit & to see if reline is indicated Slight pressure on denture base activates clasps & elevates superior border of lingual plate , results in lack of planned contact . Relining is indicated A manifestation of change in the supporting ridge to justify relining is the evidence of rotation about fulcrum line with indirect retainers lifted from their seats as RPD base is pressed posteriorly 1. If occlusal contact is lost & rotation about fulcrum line is evident , relining is indicated g 2. If occlusal contact is lost without any evidence of denture rotation & with a satisfied denture base stability , so reestablishing occlusion is needed rather than relining Superior border of lingual plate & rests are in their planned relations to natural teeth in absence of occlusal load Indirect retainer is fully seated . As pressure is applied to free-end base, indirect retainer is unseated ( a reline is needed ) FACTORS TO BE CONSIDERED IN CASE OF RELINING OR REBASING 1. Length of span 2. Amount of bone loss 3. Compressiblity of mucosa 4. Peripheral extension 5. Type of impression material used y ***IF RPD that needs refitting has abraded acrylic teeth, or broken or lost porcelain teeth, it must not be relined or rebased Lower RPD is removed to evaluate wax indentations. Absence of perforations in wax strips by opposing posterior teeth . As such , relining & correction of occlusal discrepancies are needed The difference between a reline & a rebase lies in the need to re-establish the borders of the denture IMPRESSION TECHNIQUE RPD base is prepared for reline impression by resin removal to have a space for impression material & to ensure a suitable bonding surface
    • Reline impression with ZO-E ( mobile tissue on ridge crest ) OR with rubber base and /OR wax (dense, firm tissues) LABORATORY TECHNIQUE 1. Flask method 2. Duplicating device method (Hooper duplicator as used for CD reline procedures or other Metal reline jig to preserve vertical & occlusal self-cured resin relations of RPD ( using self ) RPD to be relined is located in one part of the flask, replica of edentulous ridge in remaining part of the flask. Flask can or can not be warmed according to impression material. Secure positioning of RPD base to cast ensures no changes in VDO or in occlusal relations Relined impression is mounted on a duplicating device ( self-cured resin is used ) Stone cast recording impression part & framework is fixed to reline jig ( cast is affixed to upper or lower member ) Stone opposing cast is poured & secured to the other member of the jig.When stone sets, jig is separated , to remove RPD from the cast to relief tissue surface & borders. Self-cured acrylic resin is mixed & placed into the base Framework placed on cast & arms of jig tightened to complete closure , covered with warm water & put in a pressure pot at 20 psi / 15 minutes. INTRAORAL RELINE Adhesive tape is used to cover external surface of denture base ( to protect denture teeth). Mouthcured resin is mixed without trapping air intra-oral reline , acrylic resin extending finish line is removed as in dough like state Advantages of intraoral reline : Quick procedure. Disadvantages of intraoral reline : 1. Indicated only in temporary or transitional situation as chair side or mouth relining is inferior to lab reline. 2. Material is porous & not color stable REBASING Rebasing is the replacement of a denture base with new material without changing occlusal relation of the teeth. base RPD is relieved to resin retaining elements . Modelling compound is used for border moulding Rebasing is indicated when : 1. Denture base do not extend to cover all of the denturebearing tissue. 2. Denture base is fractured or being irreparable discolored 3. Framework good design is of & fits the teeth well. 4. When the denture is stained or discolored When peripheral borders require extensive modification, or flanges need substantial alteration , rebase is preferred over reline Under-extended form of lower RPD provides a reduced area of RR coverage that contribute to tissue irritation. When denture base is properly extended , it will enhance support , stability, i retention A sectional cast is poured against a rebase impression Desired contours are re-established with baseplate wax
    • Rebase preparation needs most of existing RPD base to be removed by a large bur RECONSTRUCTION Indications : 1. When denture base is damaged beyond repair. 2. When the fit of the denture is not satisfactory. 3. Loss , RPD bases are burned away from underlying framework before starting reconstruction RELINING NEW DENTURE : Distal –extension base RPD is border molded ,impression is obtained with ZO-E impression Relining Old Denture As a result of bone loss ,relining is indicated to correct loss of fit Distal extension saddle: Occlusal plane not changed as opposing natural teeth not extruded After reline or rebase, occlusion is equilibrated Complete denture opposing RPD that requires refitting refitting Oftentimes ,both dentures need refitting, one denture at a time Mounting RPD against upper CD. Upper denture is mounted through remount cast made after finishing & polishing of denture. Occlusal registration in hard inlay wax supported by accurate record bases Width of each cusp in . all excursive movements is recorded as continuous glossy surface Preparation for sprinkle-on record base technique. out of undercuts & cast is coated with separating medium Peripheral extent of base ( the same as peripheral extent of denture captured during impression procedure for this altered cast ) is outlined with rope wax to contain resin Cast is wetted with monomer & polymer resin is added to control thickness Record base is completed when a uniform thickness is created providing strength & accuracy Record base & framework are removed from the cast , finished and prepared for addition of occlusion rim Hard baseplate wax rim is most commonly used material to establish static occlusal relations Direct Relines: Contraindications 1. For long term service (deteriorate in oral environment) 2. Poor impression materials, which are not accurate and cause tissue displacement 3. Difficulty of material in adhering to denture base 4. Tissue surface is rough and presents porosity 5. Color stability is of short duration 6 If denture is not properly positioned correction 6. positioned, is difficult 7. Tissue irritation may be caused by lysis of the local monomer