A COMPARATIVE EVALUATION TO DETERMINE THE TENSILE BOND STRENGTH AND DRYING TIME OF DIFFERENT TRAY ADHESIVES ON A VINYL POLY SILOXANE IMPRESSION MATERIAL USING TWO DIFFERENT TRAY MATERIALS: AN IN VITRO STUDY

Introduction: A key goal in prosthodontics is obtaining an accurate impression. Although stock trays provide mechanical retention, manufacturers recommend using tray adhesive with both stock and custom trays. There is limited research on the adhesive bond strength between tray adhesives and both auto- and light-polymerizing custom tray materials. Manufacturers recommend using adhesive and impression materials from the same brand, and there is ongoing debate about the ideal drying time for tray adhesives before impressions. Aim: The aim of this study was to do a comparative evaluation to determine the tensile bond strength and drying time of different tray adhesives on a particular vinyl poly siloxane impression material using two different tray materials. Materials and Methods: A stainless-steel mold (15×15×20 mm³) was created according to ADA specification no. 19. A total of 90 samples were made, including 45 auto-polymerizing and 45 light-polymerizing resin samples, with surfaces polished using 120-grit sandpaper. An eye hook was attached to each sample, and cylindrical specimens (15 mm diameter, 20 mm height) were made from PVC to hold the impression material. Reprosil (medium-bodied) by Dentsply was used, along with three tray adhesives: Dentsply Caulk, 3M VPS, and Extreme by Medicept. A layer of adhesive was applied to the sample surfaces, dried for three intervals, and tested for tensile bond strength using a digital universal testing machine at 5 mm/min until adhesive failure. Data were then analyzed statistically. Results: The mean tensile bond strength ranged from 0.168 MPa to 1.058 MPa. The VLC acrylic resin samples showed significantly higher bond strength than self-cure acrylic samples across all drying times. Dentsply Caulk performed best with Reprosil VPS, followed by 3M VPS and Medicept's Extreme tray adhesive. Conclusion: Within the study's limitations, the manufacturer-recommended adhesive and impression material combination gave the best results. It is also concluded that a drying time of 10-15 minutes is optimal for VPS tray adhesives.