Ten-year marginal bone loss in mandibular overdentures with ball vs. locator attachments: a retrospective cohort study.

BACKGROUND

Ball and locator attachments are widely used for mandibular implant-supported overdentures (IODs), yet long-term comparative data remain limited. This retrospective cohort study evaluated 10-year marginal bone loss (MBL) and peri-implant soft-tissue outcomes in patients restored with two-implant mandibular overdentures.

METHODS

Records of patients treated between 2013 and 2014 were reviewed. Thirty-five patients with complete baseline, 1-, 5-, and 10-year clinical and radiographic data were included. MBL was measured on calibrated panoramic radiographs using a thread-based quantitative method with individualized pixel-millimeter scaling. Probing pocket depth (PPD), plaque index (PI), and gingival index (GI) were recorded at each visit. All measurements were performed by a calibrated examiner blinded to group assignment. Group comparisons were conducted at p < 0.05, and effect sizes were used to support clinical interpretation.

RESULTS

Both attachment systems showed stable peri-implant outcomes across the 10-year follow-up. MBL values were comparable between groups (p > 0.05) and remained within clinically acceptable limits. The locator group exhibited a transient mid-term increase in probing depth and gingival index, but these changes were small in magnitude, associated with medium-to-small effect sizes, and resolved by the 10-year evaluation. PI scores were similar between groups at all follow-up intervals.

CONCLUSIONS

Ball and locator attachments demonstrated comparable 10-year peri-implant outcomes, and the minor mid-term soft-tissue variations in the locator group were transient and clinically insignificant.