Comparison of Adhesion of Soft-Liner between Conventional PMMA and 3D Printed Resin Denture Bases

Aims: The purpose of this study was to evaluate the tensile strength of the soft-liner (Molloplast-B®) between the denture foundation made of 3D printed resin and traditional acrylic (PMMA). Materials and Methods: In this experiment, 60 acrylic specimens in the shape of reverse dumbbells were employed. The first group consisted of 24 specimens made from traditional acrylic polymethyl methacrylate (PMMA) (Vertex, Veracril, and Duradent) while the second group consisted of 24 specimens made from 3D printed resin (Dentona). The third group consisted of 12 samples that were packed at the dough stage of acrylic and soft liner at the same time. After that, the samples from the first and second groups were split in two, with one half receiving no surface treatment and the other half undergoing sandblasting. Every sample is separated into two halves with precise measurements. The thickest and thinnest sections were 80 mm in length (10 mm x 25 mm) and 8 mm x 15 mm, respectively, and were joined in the middle by the soft-liner material. The experiment's tensile strength was examined in two separate directions to ascertain the soft-liner material's strength of adhesion to the sample's chosen materials. Results: The data analysis of the tensile strength test revealed a statistically significant difference in the soft-liner adhesion strength between the 3D-printed acrylic resin with sandblast treatment (0.2133 ± 0.03939 kN/mm²) and the 3D-printed acrylic resin without surface treatment (0.1567 ± 0.04677 kN/mm²). Similar results were observed for conventional acrylic PMMA, where the sandblasted acrylic PMMA (0.0950 ± 0.03606 kN/mm²) exhibited significantly better bond strength compared to the untreated acrylic PMMA (0.0875 ± 0.02491 kN/mm²). Dough stage samples had better values complared to traditional acrylic (0.1483± 0.03689 kN/mm²). Conclusion: The results demonstrate that sandblast treatment significantly improves the soft-liner adhesion strength of both 3D-printed acrylic resin and conventional acrylic PMMA. Surface treatment enhances bond strength compared to untreated materials. These findings suggest that sandblasting is an effective method for improving adhesion in acrylic-based materials.