The Effect of Joint Surface Preparations and Chemical Surface Treatment on the Transverse Strength of Repaired Denture Base Resin

Aim: The aim of the study is to investigate the effect of joint surface preparations and chemical surface treatment given to prepared surface on the transverse strength of repaired denture base resin. Methodology: Two hundred and twenty specimens (DPI India) were randomly allocated into eight groups (n = 10), according to the combination of joint surface preparation (Butt joint, 45 degrees bevel, and rounded joint) and chemical surface treatment (methylene chloride, ethyl acetate, and methyl methacrylate) for 30 and 60 s each. Specimens, after surface treatment, were repaired with self-cured resin (DPI India) and then subjected to 3-point bending test to measure transverse strength. Fractured surfaces were viewed under stereomicroscope and subjected to AutoCAD analysis to determine type of failure (adhesive or cohesive) and measure their area. Measurement data were analyzed by one-way analysis of variance, paired t-test, Dunnett's D test, and multiple comparison Bonferroni t-test, with a 5% significance level. Results: Most of the comparisons between the test specimens were statistically significant. Specimens (methylene chloride for 60 s and rounded joint) show 60%-70% gain of strength. Conclusions: For providing better bond strength to a repaired specimen, the segment of fractured specimens to be provided "Rounded joint" preparation with etching by methylene chloride for 60 s.