Implant Stability, Tissue Conditions, and Patient Self‐Evaluation after Treatment with Osseointegrated Implants in the Posterior Mandible

Background: Implant treatment in the posterior mandible is considered challenging because of bone resorption and the presence of the inferior alveolar nerve, which may result in the use of short implants. Purpose: To evaluate implant stability, tissue conditions, and patient opinion after treatment with implant-supported bridges in the posterior mandible. Materials and Methods: Thirty-four patients treated with implant-supported bridges in the posterior mandible according to a two-stage protocol were clinically and radiographically examined and interviewed after a mean functional time of 3.9 years. One hundred five Branemark® implants (Nobel Biocare AB, Gothenburg, Sweden) were placed in premolar and molar regions to support 40 bridges. Twenty-eight implants were placed anterior to the mental foramen, and 77 implants were placed posterior to the mental foramen. Bridges were supported either by two or by three implants. After 2 to 6 years, the bridges were removed to analyze the resonance frequency of the implants with the use of a special instrument (Osstell™ instrument, Integration Diagnostics AB, Gothenburg, Sweden), and an implant stability quotient (ISQ) was recorded for each implant. Results: One implant was lost. An ISQ range of 59 to 90 (mean, 70.05) expressed stability of fully integrated implants in the posterior mandible. Significantly higher (p < .024) ISQ values were found in implants in three-implant bridges when compared with implants in two-implant bridges. There were no differences in ISQ values between molars/premolars, implant types, implant widths, implant lengths, anchoring depth, or uni- or bilateral mandibular bridges. Good mucosal health in the periimplant soft tissue and minor bone resorption around the implants were observed. Patients were generally very satisfied with the treatment outcome. Conclusions: High implant stability can be reached in the posterior mandible. The implants were more stable in three-implant bridges than in two-implant bridges. The patients were highly satisfied with the treatment, and few complications were seen.