Influence of implant neck design and implant-abutment connection type on peri-implant health. Radiological study.

Objective: To carry out a comparative study of two implants with different neck features and prostheses platform connection (machined with external connection and rough-surfaced with switching platform) upon peri-implant marginal bone loss, before and after functional loading.

Material And Methods: A randomized, prospective radiological study was made. Eighteen totally edentulous patients were selected. Subjects were divided into two groups according to the type of implant neck used: (a) Osseous(®), with machined surface, without microthreads, external connection, and without platform switching; and (b) Inhex(®), with treated surface, microthreads, internal connection, and platform switching. Mesial and distal marginal bone loss was measured. Implant success was assessed according to the criteria of Buser. Control timepoints were as follows: (a) at implant placement; (b) at prosthesis placement; (c) 6 months after loading; (d) 12 months after loading.

Results: Fifteen patients that received 120 dental implants were included: 47% Osseous(®) group and 53% Inhex(®) group. Global mean marginal bone loss with Osseous(®) was 0.27 ± 0.43 mm and 0.38 ± 0.51 mm as determined 6 and 12 months after prosthetic loading, respectively, whereas in the case of Inhex(®) was 0.07 ± 0.13 and 0.12 ± 0.17 mm. These differences were statistically significant (P = 0.047). Difference between Osseous(®) and Inhex(®) in maxilla (P = 0.272) and mandibular (P = 0.462) bone loss were not statistically significant.

Conclusions: Bone loss after 6 and 12 months proved statistically significant between two groups, with comparatively greater loss in the case of Osseous(®) implants vs. Inhex(®) implants. Regardless the heterogeneity of the two groups (neck shape, microthreads, surface texture), the implant-abutment connection appears to be a significant factor on peri-implant crestal bone levels. Anyway, in both groups, the values obtained were within normal ranges described in the literature.