Effect of different curing temperatures on the distortion at the posterior peripheral seal: an in vitro study.
BACKGROUND
Most of the maxillary complete dentures do not adapt accurately to the cast because of the changes in the resin during polymerization. The amount of heat associated with processing of polymethyl methacrylate has been correlated with the adaptation of the processed denture base to its supporting tissues.


OBJECTIVE
This study conducted to determine the effect of different curing temperatures on the accuracy of fit of a complete maxillary denture and to compare with that of fiber-reinforced acrylic resins.


METHODS
An ideal maxillary rubber mould used to make an edentulous cast. Forty-eight stone casts made from the ideal rubber mould. Out of 48 identical stone casts, 44 stone casts with wax adapted processed using simple acrylic resin. The remaining four stone casts were processed using fiber-reinforced acrylic resin. However, processing time for 12 hrs was maintained constant for all the samples. The variable to investigate was the temperature. Therefore, four denture bases processed at each temperature from 60°C to 80°C with two-degree increments for a total of 44 samples using simple acrylic resin. Remaining four samples processed at 70°C using fiber-reinforced acrylic resin. A traveling microscope used to measure the discrepancy between each cast and its denture base.


METHODS
Analyzed with Student's unpaired t test.


RESULTS
Minimum distortion was observed at 70°C. Maximum distortion was observed for the denture bases processed at 80°C. Amount of distortion increases as the processing temperature increases which was highly significant. Distortion was significantly high from 60 to 68°C in the decreasing order.


CONCLUSIONS
This study verified the observation that maxillary complete denture base show the greatest discrepancy at the central portion of the posterior palatal seal region as the processing temperature increases.
Department of Prosthodontics and Crown and Bridge, Gitam Dental College, Vishakapatnam, India.
Nirmala
N
Pasam
R B
RB
Hallikerimath
Aman
A
Arora
Shilpi
S
Gilra
D000180:Acrylic Resins / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D003779:Denture Design; D003827:Denture, Complete, Upper; D006801:Humans; D008422:Materials Testing; D003765:Models, Dental; D017755:Prosthesis Fitting; D012408:Rubber / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; D003764:Dental Materials; D014867:Water; D012408:Rubber; D002133:Calcium Sulfate