Purpose: Dental implant therapy is one of reliable treatment options for replacing missing teeth. Dental implants constitutively receive functional loading such as mastication and swallowing. Recently, preferential alignment of biological apatite (BAp) and osteocytes play an important role in bone mechanical function by regulating bone quality. The aim of this study was to investigate the effect of occlusal forces on the alignment of BAp c-axis and ultrastructural morphology of osteocytes in bone around implants in beagle mandibles.

Materials and Methods: Dental implants with microthreads around the neck and marothreads around the body were placed at 8 weeks after the extraction of both mandibular fourth premolars and first molars. Superstructures were cement-retained at 8 weeks after implant placement. Dental implants received occlusal forces for 24 weeks. Control group did not receive occlusal forces with the placement of healing abutments.  Scanning electron microscopy and microbeam X-ray diffractometer were used to investigate the alignment of BAp and structure of osteocytes, respectively.

Results: Bone implant to contacts were same, regardless of mechanical loads. Preferential alignment of BAp c-axis and morphology of osteocytes were the same in bone around microthreads, irrespective of mechanical loads. However, these parameters were significantly changed in bone around macrothreads under loaded conditions.

Discussion: Stress dispersion may occur in bone around microthreads due to unchanged alignment of BAp c-axis and no alteration of osteocyte morphologies. Bone quality may promote in bone around macrothreads because of preferential alignment of BAp c-axis and development osteocyte network. Stress dispersion and adaptation of bone quality might contribute to long-term clinical outcome in implant therapy.