Histological and micro-CT analysis of peri-implant soft and hard tissue healing on implants with different healing abutments configurations

Objective: The aim of this study was to assess the effect of different abutment configurations on peri-implant soft and hard tissue healing.

Materials and methods: Two-piece dental implants, 3.5 mm in diameter and 8 mm in length, were placed in four beagle dogs. Two different transmucosal healing abutment configurations were randomly selected: one with a wide emergence profile (WE) (45° angulation with implant long axis) and the other with a narrow emergence profile (NE) (15° angulation with implant long axis). After four months of healing, the animals were sacrificed. Micro-CT scans were taken for mesio-distal analysis; subsequently, the biopsies were prepared for bucco-lingual histometric analyses. Several measurements were taken using the following reference points: marginal mucosal level (MML), apical barrier epithelium (aBE), implant shoulder (IS), marginal bone crest (BC), and first bone-to-implant contact (fBIC).

Results: In the micro-CT analysis, the distance from IS-fBIC was 1.11 ± 0.66 mm for WE and 0.12 ± 0.21 mm for NE (p = 0.004). The IS-BC of WE was -0.54 ± 0.80 mm, whereas NE presented 0.76 ± 0.48 mm (p = 0.002). The histometric analysis showed that both groups presented comparable dimensions of peri-implant biologic width (p > 0.05). However, in the distance from IS to BC, the WE showed a mean distance of -0.66 ± 0.78 mm while NE was 0.06 ± 0.42 mm (p = 0.039); the IS to fBIC was 0.89 ± 0.68 mm for WE while NE was 0.30 ± 0.30 mm (p = 0.041).

Conclusion: The design of the transmucosal component can influence the establishment of the peri-implant biologic width. The flat and wide emergence profile induced an apical displacement of the peri-implant biologic width and more bone loss.