Evaluation and comparison of marginal adaptation, colour stability and fracture resistance of provisional resin crowns fabricated with conventional, CAD-milled and 3D printed techniques- a prospective within-subject clinical study”

BACKGROUND: Provisional restorations are critical in dental practice, serving multiple functions including preserving oral function and aesthetics, maintaining tooth position, and protecting dentin and pulp. Traditional materials like polymethyl methacrylate (PMMA) have limitations such as heat generation, shrinkage, and colour instability. Advances in computer-aided design and manufacturing (CAD/CAM) and 3D printing offer potential improvements. This study compared the marginal adaptation, colour stability, and fracture resistance of provisional crowns fabricated using self-cure PMMA, CAD/CAM-milled PMMA, and 3D-printed resin. METHODS: This prospective within-subject clinical study included 22 participants requiring provisional crowns for endodontically treated premolars or molars. Each participant sequentially received three crowns: self-cure PMMA, CAD/CAM-milled PMMA, and 3D-printed resin. Marginal adaptation was assessed using a digital microscope, colour stability was measured with a spectrophotometer on the day of placement and after seven days, and fracture resistance was evaluated using a universal testing machine on resin models. Data were analyzed using ANOVA with post-hoc tests. RESULTS: CAD/CAM-milled crowns demonstrated superior marginal adaptation (buccal: 30.205 µm, lingual: 27.218 µm) and fracture resistance (1059.605 N). Self-cure PMMA showed the highest colour change (ΔE = 10.591), indicating lower colour stability, and exhibited the poorest mechanical properties. 3D-printed crowns offered intermediate values across all parameters. ANOVA revealed significant differences in buccal marginal adaptation (F = 25.423, p < 0.001), fracture resistance (F = 4.975, p = 0.010), and colour stability (F = 5.319, p = 0.007). Post-hoc analyses clarified specific differences between fabrication methods. CONCLUSIONS: Within the limitations of this short-term study, CAD/CAM-milled crowns provide the best combination of marginal adaptation and mechanical durability. 3D-printed crowns show better colour stability than self-cure PMMA and a balanced performance overall. Self-cure PMMA demonstrates lower mechanical strength and higher colour change. Selection of provisional crown fabrication method should consider clinical priorities, balancing precision, durability, and aesthetics. TRIAL REGISTRATION: CTRI Reg.noCTRI/2025/03/082819.