Purpose: To evaluate the circumferential bone level and the morphological changes in posterior

mandibular ridge of mandibular overdenture wearers submitted to conventional and immediate

loading through cone beam computed tomography (CBCT) at 1 and 3 years. Material and Methods:

Twenty participants who received 2 NDI (Facility - 2.9x10 mm) were randomly allocated to the

conventional loading (CL: n=10) or immediate loading (IL: n=10) groups. CBCT scans were

performed in each group to analyze the vertical (VBL) and horizontal (HBL) bone level 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-L4). Differences between groups

were verified using the 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 HBL of -0.22 mm and VBL of -0.59 mm, respectively. After the third year,

measurements of the percentage of cortical and medullar height indicated that the IL group presented

a significantly higher percentage of cortical bone height (40.1 ± 9.3) compared to the CL group

(31.8 ± 5.8) at position L1 (P=.05). No difference was found for posterior ridge remodeling (P>.05).

Conclusions: IL group showed slightly higher values of HBL and VBL, and locally displayed more

replacement of medullary by cortical bone. However, circumferential bone level values in the IL

group are still clinically acceptable and the posterior resorption rate remained stable after 3 years of

function, irrespective of the loading type.