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Provisional Restorations Wael Al-Omari. BDS, MDentSci, PhD Functions of Provisional Restorations Comfort/tooth vitality Occlusion and positional stability Function Gingival health and contour Aesthetics Diagnosis Other practical uses Assessment of Aesthetic Changes Assess appearance of intended restorations Make directly or use a matrix made from the wax-up. Ensure patient’s acceptance Record the temporary crowns and instruct technician to copy their form ad shape into the final restoration Provisional crown can be used to assess axial and occlusal reduction Occlusal Changes Prevent unwanted tooth movement by maintaining occlusal and interproximal contacts Evaluate patient’s tolerance to change in anterior guidance or increased occlusal vertical dimension: Cement temporary crowns made from diagnostic wax up and review for aesthetics, guidance, drifting, mobility, decementation, and comfort Copy the provisional crowns guidance by a custom guidance table, to transfer to definitive restorations. It is recommended to assess tolerance to change in vertical dimension by a reversible method such as splint. Periodontal Changes Allow for resolution of inflammation Improve gingival healing and stabilization of gingival margin position Used after surgical crown lengthening during the healing period before definitive preparation and impression Preoperative Polycarbonate provisional crown cemented Gingival healing after 2 months Change in Tooth Shape Accurately copy a satisfactory and successful provisional restoration to: 1. Avoid minor or major changes in tooth shape. 2. Avoid disrupting fine mouth movements and lip/tooth contact 3. Avoid incorporating wide cervical embrasure to prevent air leakage Provisional Restorations Materials Preformed crowns Plastic shells: polycarbonate or acrylic. Used for anterior and premolar teeth. Metal Shells: aluminum, stainless steel or nickel chromium. Self or light cured resins Aluminum provisional crown Self or light cured resins Polymethyl methacrylate Polyethyl methacrylate (Snap, Trim) Bis acryl composite (Protemp) Urethane dimethacrylate (light cured). Restorative composite A- Polymethyl methacrylate B- Bis-acryl composite Cast Metal Nickel chromium, silver and scrap gold. Durable Can be made with external retention beads to retain acrylic or composite Rarely used Provisional Cements Creamy mix of zinc oxide eugenol Most practitioners use proprietary cements such as Temp Bond Available with modifier to soften the cement Non-eugenol Tem Bond is available and used to: 1. Cement temporary restorations for preparations for definitive adhesive restorations (eg All ceramic, veneers) to avoid interference with bonding of resin cements. If eugenol containing cement used, eugenol residues should be removed with pumice and water Provisional Cement (Temp Bond) Direct Provisional Restorations Techniques Proprietary Shells Plastic Shells: Polycarbonate relined with resin, trimmed, polished and cemented. Metal shells: 1. Aluminum shells: relined with resin (short term). Soft and galvanize with opposing amalgam 2. Stainless steel and nickel chromium: used with bruxist patients. Custom shells: beaded acrylic and Mill crowns Matrices for Provisional Restorations Impressions: Alginate: absorbs resin exotherm Elastomers: reusable Advantages: simple, quick, inexpensive. Vacuum formed thermoplastic: clear vinyl sheet on stone duplicate of the wax up. used only in presence of number of adjacent locating teeth could be used with light cured resins. Proprietary celluloid crown form A- Alginate impression as a matrix B- Provisionals with an excess material A preoperative silicone sectional impression The resin material in injected into the impression Techniques Direct Syringing: polyethyl methacrylate. Indirect Provisionals: Used for long term provisionals. Strong heat cured materials can be used Aesthetics and occlusion made on articulated wax up. Indicated or multiple restorations and for an increased vertical dimension. Alginate impression of the preparations, cast in fast set stone, and fabricate provisionals. A- Stone duplicate of the wax up B- Vacuum formed matrix A- preparation B-Excess film of material attached to provisional crown C-Trimming the excess D- Cemented provisional crown Provisionals of Adhesive Restorations No temporary coverage Simple coat of zinc phosphate cement Composite resin bonded to a spot etched on the preparation Composite bonded to opposing tooth Problem Solving Insufficient bulk of material: Inadequate reduction, or make it bulkier by relieving the matrix (impression). Gross occlusal errors, air blows and voids: trim away suspected areas (interpoximal), an educe hydrostatic pressure by cutting escape vent. Locking in of provisional restorations: material engaging the adjacent tooth proximal undercut. Marginal discrepancy: polymerization shrinkage, distortion on removal, reline with resin around the margins The inside of the alginate is trimmed to increase the thickness of the provisional Problem Solving Multiple crowns: joined restorations prevent drifting, gingival embrasures should be opened to access brushing. Premature decementation: Ensure harmony with occlusion, use stronger cement Partial denture abutment: fabricate with the denture fully seated. Eugenol containing cements: do not use if the underlying core is composite. Removing temporary cement: use modifier. Removal of excess cement: apply petroleum jelly to outside of the restorations Pre-operative view Linked temporary Crowns made at chairside using preoperative clear thermoplastic matrix
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