title: Dimensional stability of complete denture permanent acrylic resin denture bases; A comparison of dimensions before and after a second curing cycle.
abstract: The purpose of this study was to measure deformation of mandibular complete denture permanent bases after secondary curing. A cast of a flat mandibular edentulous ridge was duplicated ten times. A wax base was laid on the original cast, two wax sprues were attached and an overcast was made. The overcast was used to produce wax bases similar in outline and thickness on the duplicate casts. These were invested and following manufacturer's instructions ten similar acrylic resin bases were produced. The fitting surface of each denture base was scanned on a contacting scanner with an axis resolution of 1 microm and accurate to 25 microm. Denture teeth were waxed up on the base on the original master cast, an overcast was made to produce wax ups and tooth positions that were similar in outline and thickness to the original. These were processed, removed from the flasks and excess acrylic resin was removed. The denture bases were rescanned in an identical fashion to the first scanning procedure. Using commercially developed metrology software calibrated colour maps were generated for each denture base that illustrates measurements of differences between pairs of surfaces. Histograms showing distributions of distances between points were constructed. 50% of the points were separated by a mean 50 microm or less and that 90% of the points were separated by 160 microm or less. The maximum separation was of 380 microm. Complete denture permanent bases were not found to distort significantly as a result of being subjected to a second heat curing cycle as part of final processing of dentures.
authors.affiliation: King's College London Dental Institute, Guy's Hospital, London. michael.fenlon@kcl.ac.uk
authors.forename: Michael Robert
authors.initials: MR
authors.lastname: Fenlon
authors.forename: Andrzej Stanislaw
authors.initials: AS
authors.lastname: Juszczyk
authors.forename: Jose Mauricio
authors.initials: JM
authors.lastname: Rodriguez
authors.forename: Richard Victor
authors.initials: RV
authors.lastname: Curtis
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D003735:Dental Casting Technique; D003760:Dental Impression Materials / Q000737:chemistry; D003761:Dental Impression Technique; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D003779:Denture Design; D003826:Denture, Complete, Lower; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D011145:Polyvinyls / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D012984:Software; D013499:Surface Properties; D014093:Tooth, Artificial
chemical_list: D000180:Acrylic Resins; D003760:Dental Impression Materials; D003764:Dental Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D002133:Calcium Sulfate