A comparison of shear bond strength of denture teeth to denture base using different means of retention: in vitro pilot study

Abstract

Objectives: The objective of this work is to evaluate the shear bond strength between denture base resin and three different acrylic artificial denture teeth. The latter was subjected to three different surface modifications on the ridge lap area and compared to unmodified acrylic artificial denture teeth.

Methods: In this experimental in vitro study, twenty-four maxillary central incisor acrylic teeth were used from each of three manufacturers; namely Major®, Ivoclar® and Myerson®. The teeth were additionally divided into four test groups with six specimens in each: a control group, a chemical retention group, a mechanical retention group, and a mechanical plus chemical retention group. The teeth in each group, with the exception of the control group, are subjected to one of the four different surface modifications prior to packing of the denture base resin. Seventy-two acrylic resin test blocks thus obtained are submitted to 5,000 cycles of thermocycling between 5 and 55°C for 30 seconds in each water bath and 10 seconds in between. The resins are subsequently tested for shear bond strength between the acrylic resin teeth and the denture base resin in the Universal Testing Machine using the strength mode. The compression load is applied through a roll pin at a crosshead speed of 1 mm/min and at an angle of 45° (relative to the long axis of the tooth). Anova, Kolmogorov–Smirnov, Kruskal–Wallis and Post hoc tests were used for statistical data analysis. The significance level retained corresponds to a p-value ≤ 0.05.

Results: The multilayer teeth of the nano hybrid composite “Ivoclar®” had the highest bonding strength in the control and chemical bonding groups. For the mechanical or mechanical plus chemical retention groups, no significant difference between the three types of teeth was observed.

Conclusions: The multilayer nanohybrid “Ivoclar®” teeth are the most retentive teeth to the denture base. If resin teeth are desirable, applying combined retentive measures would be recommended.