PURPOSE: Clinical evidence regarding 3D-printed complete arch interim prostheses remains limited. This randomized crossover trial was designed to compare mechanical complications between milled polymethylmethacrylate (PMMA) and a hybrid ceramic 3D-printed interim restoration and assess mechanical complications, passive fit, optical behavior, and oral health-related quality of life. MATERIALS AND METHODS: Twenty edentulous patients received two complete arch interim prostheses, one milled PMMA and one hybrid ceramic resin 3D-printed restoration, each used for 3 months in a randomized crossover sequence. Mechanical complications, passive fit, optical parameters (L*, a*, b*, ΔE00), and oral health-related quality of life were assessed. Paired nonparametric tests, including the Wilcoxon signed-rank test and McNemar test, were applied (α = 0.05), and risk differences with 95% confidence intervals were calculated. RESULTS: Milled PMMA exhibited fewer mechanical complications than 3D-printed (10% vs. 45%; p = 0.016; risk difference +35.0 percentage points; 95% CI: 9.5-60.5). Passive fit showed no statistically significant differences between materials (p = 0.500). Mean ΔE00 did not differ significantly (PMMA 4.68 ± 6.57; 3D-printed 4.73 ± 4.75; p = 0.243). The 3D-printed material presented higher L* values at both evaluations (p < 0.001) and a significant increase in a* over time (p = 0.008). Both materials improved Oral Health Impact Profile-14 scores; at 3 months, 3D-printed prostheses showed slightly lower scores than PMMA (p = 0.045). CONCLUSIONS: Milled PMMA showed more favorable mechanical performance. Both materials demonstrated passive fit, stable optical behavior, and improvements in patient-reported outcomes during the 3-month period.
Vásquez et al. (Mon,) studied this question.