Implant-supported distal extension mandibular partial overdenture: comparison of two attachment types effect on mandibular posterior residual alveolar bone (five year retrospective study)

Abstract

Purpose: This study aimed to compare effect of implant supported removable partial denture (IS RPD) with locator versus ball attachments on mandibular posterior residual alveolar ridge after 5 year period. Materials and Methods: From available data base of class I partially edentulous mandibular arches modified by bilateral distal implants in 2nd molar region against edentulous maxilla treated with IS RPDs against a maxillary denture. 18 patients were randomly selected and allocated in two equal groups, 9 patient each, as follows; G1, B&S Group, using a ball and socket attachment and G2, locator group, using locator attachment. The posterior mandibular ridge resorption was evaluated in the form of change in posterior area index (∆PAI) on digital panoramic radiographs over 5 year period. Also the relation of ∆PAI to implant marginal bone changes (MBC) and other patient's data as age, edentulous period, prosthesis use period, ridge length, initial ridge height number of relines and attachment maintenance. Results: locator significantly reduce the ∆PAI (0.032) compared to B&S (0.064) with non-significant difference in MBC of distal implants. Conclusion: The IS RPD using locator attachments offer better mandibular posterior ridge preservation versus the B&S attachment. Carful follow-up and proper post insertion service help to avoid any harmful effect on implant and/or residual ridge, maintaining the prosthesis/attachment/ tissue relation to assure proper functional load distribution.