Immunohistochemical comparison of lateral bone augmentation using a synthetic TiO(2) block or a xenogeneic graft in chronic alveolar defects.

OBJECTIVES: To evaluate osteogenic markers and alveolar ridge profile changes in guided bone regeneration (GBR) of chronic noncontained bone defects using a nonresorbable TiO(2) block. MATERIALS AND METHODS: Three buccal bone defects were created in each hemimandible of eight beagle dogs and allowed to heal for 8 weeks before GBR. Treatment was assigned by block randomization: TiO(2) block: TiO(2) -scaffold and a collagen membrane, DBBM particulates: Deproteinized bovine bone mineral (DBBM) and a collagen membrane, Empty control: Only collagen membrane. Bone regeneration was assessed on two different healing timepoints: early (4 weeks) and late healing (12 weeks) using several immunohistochemistry markers including alpha-smooth muscle actin (alpha-SMA), osteopontin, osteocalcin, tartrate-resistant acid phosphatase, and collagen type I. Histomorphometry was performed on Movat Pentachrome-stained and Von Kossa/Van Gieson-stained sections. Stereolithographic (STL) models were used to compare alveolar profile changes. RESULTS: The percentage of alpha-SMA and osteopontin increased in TiO(2) group after 12 weeks of healing at the bone-scaffold interface, while collagen type I increased in the empty control group. In the defect area, alpha-SMA decreased in the empty control group, while collagen type I increased in the DBBM group. All groups maintained alveolar profile from 4 to 12 weeks, but TiO(2) group demonstrated the widest soft tissue contour profile. CONCLUSIONS: The present findings suggested contact osteogenesis when GBR is performed with a TiO(2) block or DBBM particulates. The increase in osteopontin indicated a potential for bone formation beyond 12 weeks. The alveolar profile data indicated a sustained lateral increase in lateral bone augmentation using a TiO(2) block and a collagen membrane, as compared with DBBM and a collagen membrane or a collagen membrane alone.