Investigation of the effects of different denture base fabrication techniques and hard relining resin materials on the fixation of immediate provisional hybrid prosthesis to titanium cylinders.

Background: Denture base fabrication techniques and hard relining resins play critical roles in the clinical durability of implant supported immediate provisional hybrid prostheses (IPHPs). This study aimed to investigate the effects of different denture base fabrication techniques and hard relining resins on the fixation of IPHPs to titanium cylinders using a push-out test, and observe the failure types.

Methods: A total of 140 denture base acrylic resin specimens (diameter: 24 mm, height: 4 mm) were fabricated using four techniques: milling, 3D printing, injection molding, and conventional heat-polymerization. Holes in 10 mm diameter were drilled at the center of each specimen using an industrial drill. Then, titanium cylinders (Opus Implant) were fixed to the specimens using five hard relining resin materials: acrylic resin-based (Ufi Gel Hard)(UGH), heat-polymerized acrylic resin (Futura Basic Hot)(FBH), autopolymerizing composite resin (Quick Up)(QP), autopolymerizing denture repair resin based on diacrylate (Qu-resin)(QR), and autopolymerizing low shrinkage modelling acrylic resin (Pattern resin LS)(PR) (n = 7). Following 5000 thermal-cycles, a push-out test was performed using a universal testing machine (Test Control Systems). Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey post-hoc test (SPSS26, p =.05).

Results: Denture base fabrication techniques, hard relining resin materials, and their interactions had significant effects on the push-out forces (p <.001). Statistically significant differences among fabrication techniques were observed only in the QR group (p <.05), where heat-polymerization technique had the highest push-out forces. Among relining materials, PR exhibited the highest values for milling technique (p <.05). For 3D printing, PR (p =.007) and QR (p =.029) showed significantly higher values than UGH. For injection molding, PR was superior to QP (p =.012) and UGH (p =.001). For heat-polymerization technique, QR, PR and QP exhibited the higher values (p <.05). The most common failure type was adhesive failure between titanium cylinders and relining resins (ADHES-ti).

Conclusions: Denture base fabrication techniques and relining resin types had significant effects on the push-out force. Conventional heat-polymerization technique provided the most consistent performance, whereas milling and 3D printing required careful selection of relining materials. These results can inform clinical decisions to improve IPHP durability and reduce complications.