Shear Bond Strength of Repair Materials by Different Polymerization Methods on 3D-Printed Denture Bases

To investigate shear bond strengths (SBSs) of denture repair materials using different polymerization methods to a 3D-printed denture base (DLP) compared to an autopolymerized polymethyl methacrylate denture base (PMMA).

DLP and PMMA disks were fabricated, roughened using #400 silicon carbide abrasive paper, and treated with the primer/bonding of the respective repair material. An autopolymerized denture repair material (PER) or a light-polymerized denture relining material (MRB) was polymerized on the disks. All specimens were stored in distilled water at 37°C for 24 hours. Half of the specimens underwent thermocycling (TC; 5,000 cycles, 5 to 55°C). SBS testing was conducted (n = 20 per group), and the fracture pattern was analyzed. The SBS data were analyzed using nonparametric Kruskal- Wallis tests and Weibull distributions with the maximum likelihood estimation.

MRB specimens showed significantly higher SBS and Weibull characteristic strength values than PER specimens (P < .001), irrespective of the denture base material. No statistical differences were observed in Weibull modulus among the specimens, except PMMA-MRB specimens, which showed the highest values (P < .001). Thermal aging tended to decrease these values; however, no significant differences were observed between the non-TC and TC groups. Adhesive failure was dominantly observed in the specimens, except DLP-MRB specimens, which shifted to cohesive failures within the denture base.

The repairability of the DLP specimens was comparable to those of the PMMA specimens. Thus, denture repair of the DLP denture base could be treated in the same manner as a conventional PMMA denture base.