(P06) Incidence of Peri-implant Bone Loss in Engaging versus Non-engaging Abutments in Implant-supported Fixed Dental Prostheses: A Retrospective Clinical Study

Purpose of the Study: Peri-implant marginal bone stability is essential for the long-term success of implant-supported restorations. Although both engaging and non-engaging abutments are commonly used in clinical practice, there is limited clinical evidence evaluating their influence on peri-implant bone levels. Understanding whether abutment design contributes to differences in marginal bone loss is important for optimizing implant longevity.
This study aimed to determine and compare the incidence of peri-implant bone loss in engaging and non-engaging abutments used in implant-supported fixed dental prostheses (FDPs).

Methods: A retrospective clinical study was conducted on 45 patients (28 males, 17 females) who had been rehabilitated with 72 implants. Of these, 50 implants were restored with engaging abutments (Group E) and 22 with non-engaging abutments (Group N). Only implants with radiographs of adequate diagnostic quality were included. Standardized periapical radiographs were taken at the time of FDP placement (baseline) and at the 6-month follow-up. Marginal bone levels were measured on the mesial and distal aspects of each implant. Mesial bone loss (MBL), distal bone loss (DBL), and total bone loss (TBL) were calculated for both groups. Differences in bone loss between baseline and 6 months (diff MBL, diff DBL, diff TBL) were analyzed using independent sample t-tests, with significance set at P ≤ 0.05.

Results: A statistically significant difference in marginal bone loss was observed between the two groups. Group N (non-engaging abutments) recorded higher mean values of bone resorption compared to Group E (engaging abutments). Specifically, implants restored with non-engaging abutments exhibited 0.23 mm more mesial bone loss and 0.41 mm more distal bone loss than those restored with engaging abutments. The mean total difference in bone loss was 0.18 mm for Group E and 0.50 mm for Group N over the 6-month follow-up period. These results indicate that engaging abutments were associated with reduced peri-implant bone resorption compared to non-engaging abutments.

Conclusion: Within the limitations of this study, it can be concluded that abutment design influences peri-implant marginal bone stability, with engaging abutments demonstrating significantly less bone loss than non-engaging abutments after 6 months of prosthetic loading. Clinically, while both abutment types have their indications, the use of engaging abutments may offer a bio mechanical advantage in preserving peri-implant crestal bone, thereby enhancing the long-term success of implant-supported FDPs.

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