3-Year Bone Remodeling and Atrophy in Edentulous Mandibular Overdenture Wearers

Objectives: Evaluate circumferential bone level and morphological alterations in the posterior mandibular ridge of atrophic and non-atrophic patients using implant-retained mandibular overdentures over 3 years.
Methods: 26 edentulous patients categorized according to mandibular atrophy received two narrow-diameter implants (Facility implant, 2.9x10mm) in the anterior region of the mandible. The vertical and horizontal bone level was measured along with bone remodeling at 4 distances from the mental foramen in the posterior region of the mandible (L1-L4).
Results: Significant vertical and horizontal bone level differences between and within groups were not observed. The non-atrophic group showed significantly higher total height and medullary height in all 4 evaluated regions at 1 and 3 years. Cortical height and width were also significantly higher in this group at distances L1 and L4 in year 1. The non-atrophic group shows a significantly higher % of the medullary height at distances L1, L2, and L3 after 1 year, and at all distances after 3 years. The bone remodeling in the groups differed in terms of cortical width and % medullary width at L3.
Conclusions: The atrophic group presented lower total height and medullary height, and a higher % of cortical height in the posterior region of the mandible at 1 and 3 years. Bone resorption in the posterior ridge was stabilized by mandibular overdentures, however, atrophic patients are more susceptible to the long-term substitution of medullary bone by cortical bone.