3-Year Bone Remodeling in Mandibular Overdenture Wearers: Results from an RCT Comparing Immediate vs Conventional Loading Using CBCT.

Abstract

Purpose: To evaluate the circumferential bone level and morphologic changes in the posterior mandibular ridge of mandibular overdenture wearers submitted to conventional and immediate loading through CBCT at 1 and 3 years.

Materials and methods: In total, 20 participants who received two narrow-diameter implants (NDIs; Facility-Equator, Neodent; 2.9 × 10 mm) were randomly allocated to the conventional loading (CL; n = 10) or immediate loading (IL; n = 10) group. CBCT scans were performed in each group to analyze the vertical bone level (VBL) and horizontal bone level (HBL) around the implants, analyzed together with the posterior bone remodeling of the mandible measured at distances of 5, 10, 15, and 20 mm from the mental foramen (L1 to L4, respectively). Differences between groups were verified using Student t test at a significance level of 5%.

Results: The IL group showed a significantly higher HBL in the first year (P = .028) and a significantly higher VBL in the third year (P = .032), with an HBL of -0.22 mm and VBL of -0.59 mm, respectively. After the third year, the percentage of cortical and medullary height indicated that the IL group presented a significantly higher percentage of cortical bone height (40.1 ± 9.3 mm) compared to the CL group (31.8 ± 5.8 mm) at position L1 (P = .05). No difference was found for posterior ridge remodeling (P > .05).

Conclusions: The IL group showed slightly higher HBL and VBL values and locally displayed more replacement of medullary bone by cortical bone. However, circumferential bone levels in the IL group were still clinically acceptable, and the posterior resorption rate remained stable after 3 years of function, irrespective of the loading type.