Circumferential bone loss around splinted and nonsplinted immediately loaded implants retaining mandibular overdentures: A randomized controlled clinical trial using cone beam computed tomography

Statement of problem. Circumferential marginal bone around 2 splinted and nonsplinted immediately loaded implants in the edentulous mandible has not been previously investigated. Purpose. The purpose of this randomized controlled clinical trial was to assess circumferential bone loss around splinted and nonsplinted immediately loaded implants retaining mandibular over dentures, using cone beam computed tomography (CBCT). Material and methods. Thirty participants with complete edentulism were allocated to 2 groups and received 2 implants in the canine region of the mandible. Implants were either left nonsplinted (with ball attachment [BA]) or splinted (with bar attachment [RA]). Mandibular overdentures were connected to the implants 1 week later. CBCT was used to evaluate vertical bone loss (VBL) and horizontal bone loss (HBLo) bone loss at the distal (D), buccal (B), mesial (M), and lingual (L) sites of each implant upon overdenture insertion (baseline, T0), 1 year (T1) and 3 years (T3) after insertion. Repeated measures ANOVA was used for statistical analysis (alpha=.05). Results. No significant difference in the survival rate (93.3% for BA and 100% for RA) was found between groups (P=.156). VBL and HBLo increased significantly at T3 compared with T1 for both groups (P<.005). After 3 years, VBL were 1.36 +/- 0.57 mm and 1.0 +/- 0.44 mm and HBLo were 0.88 +/- 0.48 mm for BA and 0.77 +/- 0.53 mm for RA. At T1 and T3, BA had more significant VBL than RA (P<.001), while HBLo did not differ significantly between groups. For both groups, a significant difference was found in VBL and HBLo between implant sites (P<.001). The B site recorded the highest VBL, and the L site recorded the lowest VBL. The M and D sites recorded the highest HBLo, and the B and L sites recorded the lowest HBLo. Conclusions. Two nonsplinted immediately loaded implants retaining mandibular overdentures were associated with significantly higher vertical and horizontal circumferential bone loss than those associated with splinted implants after a follow-up of 3 years.