Early marginal peri-implant bone loss around tissue-level implants: a retrospective radiographic evaluation.

Objectives: To retrospectively assess the potential impact of biological and host factors on radiographic bone loss following tissue-level implant placement and prosthetic rehabilitation.

Methods: The University database was reviewed to identify patients treated with tissue-level implants between 2006 and 2020 at the University of Zurich, Switzerland. The study included patients who received screw-retained implant rehabilitations in the posterior area without simultaneous hard- or soft-tissue augmentations and had a follow-up period of at least 12 months. Radiographic measures of marginal bone loss and supracrestal tissue height were conducted using periapical x-rays at different time points. Additional factors analysed included age, gender, smoking status, history of periodontitis, jaw of treatment, type of reconstruction, and prosthetic emergence angle. Associations between marginal bone loss and potential explanatory variables were visualised and analysed. Elastic net regressions were applied to examine potential relationships with marginal bone loss.

Results: A total of 1,479 patients were treated with tissue-level implants. After applying inclusion and exclusion criteria, 106 patients with 106 implants were included in the statistical evaluation after one year (T1, n = 106 implants), and 59 patients with 59 implants were evaluated after three years (T2, n = 59 implants). The mean marginal bone loss was 0.93 mm (SD 0.83) at T1 and 1.04 mm (SD 0.97) at T2. A strong correlation (Spearman) was found between mesial and distal bone loss. Smoking status and the jaw undergoing treatment were associated with bone loss. While these associations were observed in the univariate analysis, a more comprehensive multivariate analysis revealed that these variables had a limited effect on explaining radiographic bone loss.

Conclusions: During the initial rehabilitation period in tissue-level implants in this cohort smoking status and jaw of treatment seemed to influence early peri-implant bone loss. Further, a strong correlation between mesial and distal MBL was observed. Additional research is required to determine factors contributing to early bone loss following implant-prosthetic rehabilitation.