Abstract: PURPOSE: To investigate the alterations of soft and hard tissue around implants with different insertion depth. METHODS: Bilateral premolars of 6 adult Labrador dogs were extracted and 24 implants were immediately placed into the extraction sockets with various insertion depths. Straumann^® Bone Level (BL) implants were positioned at 4 levels: 2 mm below, 1 mm below, flush with, and 1 mm above the alveolar crest. Six months after implant placement, all animals were sacrificed to obtain undecalcified block sections for histological analysis. Vertical bone loss and biologic width were recorded. SPSS 19.0 software package was used for data analysis. RESULTS: All implants osseointegrated uneventfully. The most significant bone resorption was observed when implants were inserted 2 mm below the buccal wall of the sockets(P<0.05). No significant difference in biologic widths was found. CONCLUSIONS: The insertion depths appeared to have influence on bone remodeling around implants in fresh extraction sockets. More pronounced vertical bone resorption was observed when implants were inserted 2 mm below the buccal alveolar ridge.

Key words: Alveolar bone remodeling, Animal model, Dental implant, Immediate placement, Insertion depth