Marginal bone loss and associated factors in immediate dental implants: a retrospective clinical study.

PURPOSE: The aim of this study was to evaluate the marginal bone loss (MBL) over a follow-up period of up to 36 months in Immediate dental implants (IDIs), as well as the impact of various clinical variables on the MBL. METHODS: IDIs placed in two surgical phases were evaluated. Implants were classified into bone loss (BL, exposed threads), bone remodeling (BR, crestal bone at the implant margin +/- 0.1 mm), and bone overlapping (BO, bone above the abutment). RESULTS: A total of 1,040 IDIs were inserted in 344 patients with a successful osseointegration rate of 98.9%. The average MBL at 2, 6, 12, 24, and 36 months was - 0.3 +/- - 1.0 mm, - 1.1 +/- -1.8 mm, - 1.4 +/- - 1.8 mm, - 1.7 +/- - 1.9 mm, and - 1.3 +/- - 2.3 mm, respectively. In the Baseline-12-month period, 17.5% of the IDIs presented BL, 9% BR, and 73.5% BO. For the B1-12 month period, 19.8% presented BL, 10.7% BR, and 69.5% BO. Mixed regression models showed significant MBL overtime pre-loading (p < 0.0001), stabilizing at 8.5 months from implantation. Immediate mandibular implants had lower MBL (p = 0.0365). Post-loading, MBL was lower in the mandible (p = 0.0095) and positively influenced by abutment height and rotational abutments. CONCLUSIONS: The present study supports the clinical efficacy of the IDIs placement protocol with high survival rates and acceptable MBL. It is recommended to place bone level implants slightly below the crest to ensure the platform remains at an optimal depth during the initial bone remodeling phase post-implantation.