Molar replacement with 7 mm-wide diameter implants: To place the implant immediately or to wait 4 months after socket preservation? 1 year after loading results from a randomised controlled trial

Purpose: To test the hypothesis that there is no difference in clinical, radiographic and aesthetic outcomes positioning single post-extractive 7 mm-diameter implants or waiting 4 months after molar extraction and socket preservation procedure. Material and Methods: Patients requiring one implant-supported single restoration to replace a failing tooth in the molar region of both maxilla and mandible were selected. Patients were randomised according to a parallel group design into two arms: implant installation in fresh extraction sockets grafted with cortico-cancellous heterologous bone and porcine derma (group A) or delayed implant installation 4 months after tooth extraction and socket preservation using the same materials (group B). Implants were submerged for 4 months. The primary outcome measures were the success rates of the implants and prostheses and the occurrence of any surgical and prosthetic complications during the entire follow-up. Secondary outcome measures were: peri-implant marginal bone level (MBL) changes, resonance frequency analysis (ISQ) and pink esthetic score (PES) values at implant placement (baseline) up to 1 year after loading. Results: Twelve patients were randomised to group A and 12 to group B. No patient dropped out within 1 year after loading. No implant and prosthesis failed and no complications occurred during the entire follow-up. One year after loading, statistically significant higher mean MBL loss was experienced in group A (0.63 mm ± 0.31 mm) compared to group B (0.23 mm ± 0.06 mm); difference 0.41 mm (95% CI 0.17-0.53; P = 0.001). Six months after implant placement, mean ISQ value was 78.8 ± 2.8 for group A and 79.9 ± 3.6 for group B, showing no statistically significant difference between groups (difference 1.1; 95% CI: 0.04 to 2.96; P = 0.422). One year after loading, mean PES was 10.6 ± 1.8 [range: 8 to13] in group A and 12.2 ± 1.2 [range: 11 to 14] in group B. The difference was statistically significant (1.6 ± 2.7; 95% CI -0.55-2.55; P = 0.019) with better results for group B. Conclusions: Within the limitations of this study, both procedures achieved successful results over the 1-year follow-up period, but waiting 4 months after tooth extraction and socket preservation procedure was associated with less marginal bone loss and a better aesthetic outcome.