This study aimed to evaluate and compare the tensile bond strength between four different impression materials and custom trays fabricated using various photopolymer-based three-dimensional (3D) printing materials and one conventional method. Additionally, the effect of three surface treatments on bond strength was investigated. A total of 288 custom tray specimens were fabricated using four different techniques: Stereolithography (SLA), liquid crystal display (LCD), digital light processing (DLP), and a conventional light-cured urethane dimethacrylate (UDMA)-based acrylic. Each tray type was subjected to three surface treatments: adhesive-only, perforated-only, and perforated + adhesive. Four elastomeric impression materials were tested: polyvinylsiloxane, condensation silicone, polyether, and vinylsiloxanether. A standardized CAD model was used for all trays. The impression materials were applied onto the tray surfaces, and tensile bond strength was tested using a universal testing machine. Each condition was tested with six replicates (n = 6). Data were recorded in Newtons and converted to megapascal (MPa) using a standardized bonding surface area of 825 mm². Three-way ANOVA and Tukey’s post-hoc tests were conducted (α = 0.05). All three independent variables - printing technique, surface treatment, and impression material - had a statistically significant effect on tensile bond strength (p < 0.001). The highest mean bond strength (0.272 MPa) was observed with the DLP-printed tray using perforated-only and polyether impression material. The lowest value (0.018 MPa) was found with the same tray type and surface treatment, but with condensation silicone. Among surface treatments, adhesive-only and adhesive + perforated trays showed significantly higher bond strengths compared to perforated-only groups (p = 0.001). Polyether showed significantly higher bond strength than all other impression materials, while condensation silicone yielded the lowest. Within the limitations of this in vitro study, tray fabrication method and surface treatment significantly influenced bonding with impression materials. The present findings may provide useful preliminary data for future clinical investigations evaluating retention characteristics of 3D-printed custom trays.
Topalan et al. (Thu,) studied this question.