A Study to Assess the Bond Strength of Acrylic Teeth With Different Retentive Features

Flexible denture base has been gaining attention as a denture base material because of its toxicological safety, comfort, and enhanced aesthetics. Debonding of acrylic teeth from the flexible denture base material has posed a great problem to the clinician and patient. This study aimed at comparing the bond strength between flexible denture base with acrylic teeth having different mechanical modifications.

Forty mandibular molar teeth (Combination Acry Rock, Badia Polesine (Ro), Italy) were used in four groups for mechanical modifications on the ridge lap area. The groups were group 1 (no mechanical modifications), group 2 (round groove 2 mm in diameter and 2 mm deep on the ridge lap surface), group 3 (horizontal slot 2 mm deep, 2 mm wide, and 4 mm long prepared on the ridge lap surface of the teeth), and group 4 (T-shaped groove 2 mm deep, 2 mm wide, and length of 4 mm mesiodistally and 2 mm buccolingually prepared with a straight fissure bur). The acrylic teeth were attached to a wax block of dimension 1.2 cm × 1.2 cm × 2.5 cm. These were flasked and dewaxed, followed by injection molding with Valplast flexible denture base material. The bond strength was assessed by attaching the specimens to universal testing machine tested under a tensile load at a cross-head speed of 1 mm/min till it fractured. Data obtained were statistically evaluated by one-way analysis of variance and post hoc test.

There was significant increase in mean bond strength after various mechanical modifications. Group with T-shaped diatoric hole showed greatest bond strength value compared to other groups.

Incorporating mechanical retentive features with increased surface area and undercut can improve the bonding of acrylic teeth to flexible denture base.