Bond Strength of Denture Teeth to Conventional, Milled and 3D-Printed Denture Bases

Abstract

OBJECTIVE: This in vitro study assessed the shear bond strength and failure modes between denture teeth and denture bases fabricated using conventional, two-part milled, monolithic milled, or 3D-printed complete denture techniques.

MATERIALS AND METHODS:A total of 40 denture base substrates (30 mm diameter x 10 mm height) were processed according to the following material treatment groups, n=10 for all groups: (1) Conventional complete denture processed using heat-polymerized resin (Lucitone 199, Dentsply Sirona) as a control; (2) 3D-printed denture resins (Lucitone Digital IPN 3D Premium, shade A1, and Lucitone Digital Print 3D Denture Resin, Original); (3) Two-part milled dentures from pre-polymerized polymethylmethacrylate pucks (Lucitone Digital Fit Denture Base Disc, Dentsply Sirona; Multilayer PMMA Discs, Dentsply Sirona), and (4) Monolithic milling denture (AvaDent, Extreme cross-linked PMMA). For all groups, prefabricated denture teeth or bases were embedded in autopolymerizing acrylic resin, except for Group four, in which the base and teeth were fabricated as a single unit. After embedding, specimens were polished using 400-grit sandpaper to achieve uniform surface exposure. The bonding of the two parts, base and teeth, was performed according to each manufacturer’s protocol. All specimens were tested within 24 hours of bonding. Shear bond strength was measured using a universal testing machine at a crosshead speed of 1 mm/min. The mode of failure was observed and recorded. Data were analyzed using one-way ANOVA followed by Tukey post hoc test at a significance level of α = 0.05.

RESULTS: The monolithic milling group demonstrated the highest bond strength among all groups, with statistically significant differences compared to the others (p < 0.01), with 100% cohesive failure. The 3D printed group exhibited a significantly higher mean bond strength than both the conventional and milled groups (p = 0.001), with 70% of mixed failure. There was no significant difference between the conventional and milled groups (p = 0.98), which represent 90% and 100% of adhesive failure, respectively.

CONCLUSIONS: Among all groups, the monolithic milled dentures (AvaDent) demonstrated the highest bond strength at the base-to-tooth interface. The 3D-printed denture specimens showed greater base-to-tooth bond strengths compared to both the conventionally processed and the two-part milled dentures, which showed no significant difference from each other.