Immediate occluding definitive partial fixed prosthesis versus non-occluding provisional restorations - 4-month post-loading results from a pragmatic multicenter randomised controlled trial

Purpose: To compare the clinical outcome of dental implants restored with definitive occluding partial fixed prostheses within 1 week, after implant placement with immediate non-occluding provisional restorations, which were to be replaced by definitive prostheses after 4 months. Materials and methods: Fifty partially edentulous patients treated with one to three dental implants, at least 8.5 mm long and 4.0 mm wide inserted with a torque of at least 35 Ncm, were randomised in two groups of 25 patients each, to be immediately loaded with partial fixed prostheses. Patients of one group received one definitive screw-retained metal-ceramic prosthesis in occlusion within 1 week after placement. Patients of the other group received one non-occluding provisional acrylic reinforced prosthesis within 24 h after implant placement. Provisional prostheses were replaced after 4 months by definitive ones. The follow-up for all patients was 4-months post-loading. Outcome measures were prosthesis and implant failures, any complications, peri-implant marginal bone level changes, aesthetic evaluation by a clinician, patient satisfaction, chair time and number of visits at the dental office from implant placement to delivery of definitive restorations. Results: No patient dropped out. Two immediately occlusally loaded implants with their related definitive prostheses (8%) failed early (difference in proportions = 0.08; 95% CI: -0.03 to 0.19; P = 0.490). Four complications occurred in the occlusal group versus one in the non-occlusal group; (difference in proportions = 0.12; 95% CI: -0.04 to 0.28; P = 0.349). Four months after loading, patients subjected to non-occlusal loading lost an average of 0.72 mm of peri-implant bone versus 0.99 mm of patients restored with occluding definitive partial fixed prostheses. There were no statistically significant differences for marginal bone level changes between the two groups (mean difference = -0.27 mm; 95% CI: -0.84 to 0.30; P = 0.349). The differences for aesthetic scores showed no statistical significance (8.26 versus 7.58; P = 0.445); the same was seen for aesthetics evaluated by patients (Mann-Whitney U test: P = 0.618). Patients in the non-occlusal group were significantly more satisfied with the function of their implant-supported prostheses (Mann-Whitney U test: P = 0.039). Significantly less chair time (mean difference = -28.4 min; 95% CI: -48.82 to -7.99; P = 0.007) and the number of visits (mean difference = -1.88; 95% CI: -2.43 to -1.33; P 0.001) were required for the immediate definitive prosthesis group. Conclusion: This study did not provide a conclusive answer but may suggest that provisional prostheses non-occlusally immediately loaded may increase patient functional satisfaction, chair time and the number of visits, with respect to definitive prostheses immediately loaded in functional occlusion. Parole chiave: immediate loading, non-occlusal loading, partial edentulism