Marginal Bone Loss and Stability of Single-Implants Retaining Mandibular Overdentures

Objectives: The aim of this study was to evaluate marginal bone loss and stability of single-implants retaining mandibular overdentures by using direct (bone probing) and indirect (radiographic measurement) methods, during the 12-month follow-up period.
Methods: Twenty-two edentulous patients (10 males and 12 females) with a mean age of 74.2 years (range 61-91 years) were enrolled in this study. A single implant (SLA BLT 4.1×10mm, Straumann AG, Basel, Switzerland) was placed in the midline of the mandible following a conventional loading protocol. After the healing period, locator attachments were connected to the implants. Marginal bone loss and implant stability were evaluated at implant placement (baseline) and 12-month follow-up visits. The implant stability quotient (ISQ) was recorded using a resonance frequency analysis device (Osstell, Gothenburg, Sweden). Direct measurements of the bony crest height were obtained at buccal, lingual, right, left positions of the implant with a customized abutment; and the radiographic assessment was conducted using standardized periapical radiographs with a long cone technique. Wilcoxon signed-rank test was performed to find differences between baseline and 12-month evaluations (α=0.05).
Results: One implant was lost two months after the surgery, resulting in 21 patients for data analyses. The implant survival rate at 12-month follow-up was 95.5%. The mean change in ISQ was -1.14±4.24. In direct measurement, the mean bone loss was 0.67±0.79 mm. In radiographic measurement, the mean bone loss was 0.64±0.5 mm. There was a significant difference after 12 months in both direct and radiographic measurement.
Conclusions: Marginal bone loss, implant stability, and survival rate of implants in single implant overdentures were comparable with previous reports. Single-implant treatment may be a feasible option for edentulous patients, especially geriatric population.