Implant survival/success and peri‐implant outcomes of titanium‐zirconium mini implants for mandibular overdentures: Results from a 1‐year randomized clinical trial

Objective To report the 1‐year implant survival/success and peri‐implant outcomes of mandibular overdentures retained by four titanium‐zirconium mini implants (Straumann® Mini Implant System), and to assess how surgery and loading protocols influence these outcomes. Materials and Methods A 2 × 2 factorial randomized clinical trial (RCT) tested the combined effects of two loading protocols (immediate or delayed) and two surgical approaches (flapless or flapped) on the success/survival of the mini implants, and peri‐implant parameters (plaque, bleeding, sulcus depth, gingival position, and marginal bone loss). Outcomes were assessed up to 1‐year after loading, and generalized estimating equations (GEEs) were used to analyze longitudinal and within‐patient clustered data. Results Two hundred and ninety‐six implants were placed in 74 patients. The implant survival/success rates after 1 year were 100%, and no major biological complications were observed. After 1‐year, descriptive data suggest no noticeable changes in plaque scores, whilst a reduction in bleeding scores at the 6‐month and 1‐year follow‐ups compared to baseline. Good longitudinal stability was observed for the probing depth and gingival margin height measures. Overall mean marginal bone loss was 0.68 (±0.68) mm after 3 months and 0.89 (±0.75) mm after 1‐year. The flapless protocol showed better results on soft tissue stability and health but a slightly higher risk for marginal bone loss. Conclusion The results of this RCT suggest that mandibular overdentures retained by this novel mini implant system represent a safe and predictable treatment option as confirmed by implant survival/success and peri‐implant outcomes, even when flapless surgery and immediate loading protocols are adopted.