The effect of surface treatment and salivary contamination on the tensile bond strength between acrylic custom tray and monophase polyvinyl siloxane impression material.

Abstract

Monophase elastomeric impression materials are commonly used with acrylic custom trays. Every effort is made to maximize bonding between the two. Lot of studies have focused on variables like adhesive drying time, tray material and type of elastomer but very few have solely concentrated on efficacy of surface treatment and effect of salivary contamination of the custom tray. The objective of this study was to find out the most effective surface treatment for the custom tray and also find out the extent to which salivary contamination could affect bond strengths. This invitro study was carried out in two parts using 40 samples. The materials used were Reprosil monophase impression materials and autoploymerizing acrylic blocks. The samples were divided into four groups of five samples each. The first part of the study concentrated on finding out the effect of surface treatment of the tray and the second part focused on the effect of salivary contamination. The specimens were tested in an Instron testing machine and the results of the study were interpreted by statistical analysis to arrive at the conclusions. The results showed statistically significant increase in tensile strengths for surfaces subjected to grit blasting and roughening with bur and decrease for specimens cured against wax. Salivary contamination of the tray prior to adhesive application decreased bond strengths significantly. It was concluded from the study that mechanical treatment of the tray prior to adhesive application maximizes adhesion of the impression material and that salivary contamination of the custom tray prior to adhesive application reduces adhesion between tray and elastomer regardless of the surface treatment carried out