10-Year Outcome of Small-Diameter Implants Supporting Mandibular Overdentures

Objectives: This double-blind, multicentric, randomized controlled trial aimed to evaluate and compare the long-term outcomes of titanium-zirconium (TiZr) and Grade IV titanium (Ti) small-diameter (3.3mm) implants in mandibular overdentures.
Methods: Material and Methods: 91 participants received two interforaminal implants in their edentulous mandible. Implants were identical in design (diameter: 3.3mm; type: Bone-Level, surface: SLActive^®) but differed in their material composition [Experimental group (EG): TiZr (Roxolid); Control group (CG): Ti Grade IV]. Allocation was double-blinded, and the implants were randomly assigned to either side of the edentulous mandible within the interforaminal region, in a split-mouth design. Outcome measures included implant survival- and success- rates, soft tissue conditions, radiographical peri-implant bone-level changes, safety, and Oral Health-Related Quality of Life (OHRQoL) measured using the OHIP-Edent questionnaire.
Results: Results: 50 participants completed the 10-year recall examination. 36 participants were valid for the Intent-to-treat (ITT) data set. The implant success rate was calculated as 94.6% and 91.9% for EG and CG, respectively. Four implants were lost (TiZr=1; Ti=3) in the entire study period. Kaplan-Meier survival analyses estimated an overall implant survival of 94.7% for both treatment groups (EG=98.9%; CG= 95.8%). The mean overall- and functional- crestal bone loss, was 1.49±1.37mm and 0.82±1.09mm in the EG, and was 1.56±1.34mm and 0.85±1.16mm in the CG. The mean OHIP-EDENT score was 5.49 (95%CI). No significant differences were observed in the soft tissues between the implant types.
Conclusions: Conclusion: This RCT provides robust evidence to support the clinical performance of the small diameter TiZr (Roxolid) implants in the edentulous mandible for supporting overdentures demonstrating high implant success- and survival- rates with acceptable bone-level changes, observed over a 10-year functional period.