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Information about RECORD BASES

Published on March 16, 2014

Author: seenasam52


RECORD BASES: RECORD BASES DEFINITION: DEFINITION A record base is a temporary form representing the base of a denture. It is used in recording maxillo -mandibular relations and in the arrangement of the teeth. An interim denture base used to support the record rim material for recording maxillo -mandibular records [GPT-8] SYNONYMS: SYNONYMS BASE PLATE TEMPORARY/DENTURE BASE TRIAL BASE TRANSFER BASE DIAGNOSTIC FUNCTIONS: DIAGNOSTIC FUNCTIONS To determine the accuracy of the impression procedure To see if a gag reflex is present To observe if salivary flow is adequate or not REQUIREMENTS: REQUIREMENTS Should be rigid Should be accurate Should be stable The borders should be round & smooth as the borders of finished dentures REQUIREMENTS: REQUIREMENTS Should be thin at the crest ,labial & buccal slopes to provide space for tooth arrangement Should adapt to the tissues like a finished denture Should not irritate the oral tissues Should not abrade the cast on placement and removal OBJECTIVES: OBJECTIVES To retain the recording medium or device used for recording maxillomandibular relations. To aid in transfer of accurate jaw relation ships to an articulator . To enable the setting of artificial teeth for the trial denture. PowerPoint Presentation: M axillomandibular relations are difficult to record accurately on poorly fitting bases fabricated from bulky material and from material that is subject to distortion and dimensional change . R ecord bases are made of several different materials. TYPES OF RECORD BASE: TYPES OF RECORD BASE Temporary record bases : They are discarded and replaced by denture base material, once their role in establishing jaw relation, teeth arrangement and try in is complete. Permanent record bases : They are not discarded and become part of the actual base of the finished complete denture. MATERIALS:  MATERIALS TEMPORARY RECORD BASE MATERIALS PERMANENT RECORD BASE MATERIALS Shellac base plate Reinforced shellac base plate Cold cure acrylic resin Visible light cure acrylic resin Vacuum formed vinyl and polystyrene Base plate wax Heat cure acrylic resin Gold Chromium-cobalt alloy Chromium-nickel alloy Swaged metal base Temporary bases: Temporary bases SHELLAC BASE PLATE: SHELLAC BASE PLATE Advantages: They will adapt to give intimate contact with the master cast. Require short time for construction. Inexpensive . Can be corrected easily by reheating and readapting to the master cast. Uniform thickness . SHELLAC BASE PLATE: SHELLAC BASE PLATE Disadvantages: Although shellac record bases are easily and quickly adapted, they are not considered satisfactory. They warp, do not fit accurately Distort easily Lack rigidity Become brittle and break Will not permit polishing of the borders Shellac Manipulation : S hellac M anipulation Any undercuts are relieved, and separating medium is applied to the cast. The shellac record base forms are manufactured in the shapes of the maxillary and mandibular arches. Shellac Manipulation : S hellac M anipulation The forms are softened with an open flame and molded to the cast with an instrument or the fingers. While the material is in a softened state, the excess is removed with scissors. After hardening, the borders are smoothed but as a rule will not take a polish. REINFORCED SHELLAC: : REINFORCED SHELLAC:  A flattened wire [12-14 gauge] is contoured and adapted across the posterior palatal seal area of the maxillary record base and adapted to the lingual flange of the mandibular record base and incorporated in the base. REINFORCED SHELLAC: : REINFORCED SHELLAC:  Disadvantages : Although this procedure results in a base that is more rigid and stable than shellac but its still subject to distortion and breakage. It is bulky. COLD CURE ACRYLIC RESIN: COLD CURE ACRYLIC RESIN Advantages : Good strength no need for reinforcement Good dimensional stability Does not wrap during manipulation Closely fit to the master cast   COLD CURE ACRYLIC RESIN: COLD CURE ACRYLIC RESIN   Disadvantages: Require more time in fabrication Difficult to control the thickness Residual monomer can cause irritation to oral tissues PowerPoint Presentation: Methods :  Sprinkle on method Finger adapted dough method Stone mold dough method Wax-confined dough method Flasking method Roller board/ adapting method VISIBLE LIGHT CURED ACRYLIC RESIN: VISIBLE LIGHT CURED ACRYLIC RESIN Undercuts are relieved, and separating medium is applied to the cast. Adapt a sheet of pink base plate material to the cast by fingers and prevent trapping of air . VISIBLE LIGHT CURED ACRYLIC RESIN: VISIBLE LIGHT CURED ACRYLIC RESIN Extend the material to the depth of vestibule. Cure the record base for 4 minutes in the light cure unit. Carefully removed from the cast, invert and cure the tissue surface for 4 minutes. The processed base is removed from the cast, smoothed, and polished at the borders VACUUM FORMED VINYL AND POLYSTYRENE: VACUUM FORMED VINYL AND POLYSTYRENE U ndercuts are relieved and separating medium is applied to the cast. A sheet of base plate material placed over the cast and inserted in the vaccum chamber. Electric heater switched to heat the sheet. Turn on the vacuum. The sheet will adapt closely to the cast. Switch of the heater and allow the record base to cool. Remove the record base and cut the excess material. VACUUM FORMED VINYL AND POLYSTYRENE: VACUUM FORMED VINYL AND POLYSTYRENE Advantages Easy to fabricate Uniform thickness Accurate adaptation to the master cast Good rigidity Disadvantages Expensive Difficult to form smooth rounded borders BASE PLATE WAX: BASE PLATE WAX Wet the cast. Soften the base plate wax over the flame and adapt it to master cast. Remove the excess wax and make the borders round and smooth . BASE PLATE WAX: BASE PLATE WAX Advantages Easy and rapid method Inexpensive and available Disadvantages It lacks rigidity It lacks dimensional stability Permanent denture bases: Permanent denture bases HEAT PROCESSED ACRYLIC RESIN: HEAT PROCESSED ACRYLIC RESIN A wax pattern is constructed over the cast with a thickness and contour desired for complete denture. The cast and pattern are flasked , the wax is eliminated, acrylic resin is packed and heat processed. The processed base is removed from the cast, smoothed, and polished at the borders . HEAT PROCESSED ACRYLIC RESIN: HEAT PROCESSED ACRYLIC RESIN Advantages : they are rigid, accurate, stable, not subject to distortion, and suitable for arrangement of teeth. Disadvantages : require considerable time, more expensive, cast duplication required METAL BASE PLATES: METAL BASE PLATES Made by casting gold or base metal alloys. Artificial teeth are set in wax on the denture base and later replaced with processed acrylic resin METAL BASE PLATES:  METAL BASE PLATES Advantages : No warpage High strength More accurate Produce less tissue irritation Easy to maintain Good thermal conductivity Disadvantages : Expensive Difficult to reline or rebase Time consuming PowerPoint Presentation: THANK YOU

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