Immediate loading of occluding definitive partial fixed prostheses vs non-occluding provisional restorations - 3-year post-loading results from a pragmatic multicentre 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 to be replaced by definitive prostheses after 4 months. Materials and methods: Forty 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 20 patients each, to be immediately loaded with partial fixed prostheses. Patients in one group received one definitive screw-retained, metal-ceramic prosthesis in occlusion within 1 week after placement. Patients in the other group received one non-occluding provisional acrylic reinforced prosthesis within 24 h of implant placement. Provisional prostheses were replaced by definitive ones after 4 months. The follow-up for all patients was 3 years post-loading. Outcome measures were prosthesis and implant failures, any complications, peri-implant marginal bone level changes, aesthetic evaluation by a dental practitioner, patient satisfaction, chair time and number of visits at the dental office from implant placement to delivery of definitive restorations. Results: Three patients dropped out, one from the non-occlusal group and two from the occlusal group. Two immediately occlusally loaded implants with their related definitive prostheses failed early (difference in proportions = 0.10; 95% CI = -0.03 to 0.23; P = 0.488). Five patients from the occlusally loaded group were affected by six complications vs three patients (three complications) in the non-occlusally loaded group. The difference in proportions was not statistically significant (difference in proportions = 0.08; 95% CI = -0.17 to 0.34; P = 0.697). Three years after loading, patients subjected to occlusal loading lost an average of 1.13 mm of peri-implant bone vs 1.03 mm of patients restored with non-occluding definitive partial fixed prostheses. There were no statistically significant differences for marginal bone level changes between the two groups (mean difference = 0.10 mm; 95% CI -0.62 to 0.82; P = 0.779). No significant were the differences for pink aesthetic scores (7.09 vs 6.90; P = 0.873); for aesthetics evaluated by patients (Mann-Whitney U test P = 0.799) and function satisfaction (Mann-Whitney U test P = 0.578). Significantly less chair time (mean difference -38.00; 95% CI -58.96 to -17.04; P = 0.001) and number of visits (mean difference -2.15; 95% CI -2.77 to -1.53; P < 0.001) were required for the immediate definitive prosthesis group. Conclusions: This study did not provide a conclusive answer, but suggests that immediate occlusal loading by manufacturing immediate definitive partial fixed prostheses decreases chair time and number of visits. Conflict of interest statement: Zimmer-Biomet, the manufacturer of the implants, bone substitutes and resorbable membranes used in this investigation, supported this trial, however data belonged to the authors and by no means did the sponsor interfere with the conduct of the trial or the publication of its results.