Immunohistochemical comparison of lateral bone augmentation using a synthetic <scp> TiO 2 </scp> 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 non-contained bone defects using a non-resorbable TiO2 block. Material 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 randomisation: TiO2 block: TiO2-scaffold and a collagen membrane, DBBM particulates: Deproteinised 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 (α-SMA), osteopontin, osteocalcin, tartrate-resistant acid phosphatase and collagen type I. Histomorphometry was performed on Movat Pentachrome and Von Kossa/Van Gieson stained sections. Stereolithographic models were used to compare alveolar profile changes. Results The percentage of α-SMA and osteopontin increased in TiO2 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, α-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 TiO2 group demonstrated the widest soft tissue contour profile. Conclusions The present findings suggested contact osteogenesis when GBR is performed with a TiO2 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 TiO2 block and a collagen membrane, as compared to DBBM and a collagen membrane or a collagen membrane alone.