Use of bovine hydroxyapatite with or without biomembrane in sinus lift in rabbits: histopathologic analysis and immune expression of core binding factor 1 and vascular endothelium growth factor.

PURPOSE: Considering the clinical discussion on the necessity of using a barrier membrane in the osteotomy area of sinus lift procedures to prevent fibrous tissue formation in this area and as a physical limit, the aim of this study was to analyze and compare the use of bovine hydroxyapatite (HA) with and without a biologic membrane by histopathologic analysis and immune expression of core binding factor 1 and vascular endothelium growth factor in the sinus lift in rabbits. MATERIALS AND METHODS: Sixteen male rabbits underwent bilateral sinus lift procedures and were divided into 2 groups according to the sinus filling material: group 1 received bovine HA (Bio-Oss; Geistlich Pharma AG, Wohlhusen, Switzerland) and group 2 received bovine HA and a nonporous polytetrafluorethylene membrane. All groups were sacrificed after 7, 14, 30, and 60 days for microscopic, histomorphometric, and immunohistochemical analyses. RESULTS: Microscopic analysis showed a similar bone repair pattern between the tested groups. New bone formation, soft tissue, and the remaining material were analyzed by histomorphometric analysis. No statistically significant differences (P > .05) were detected between groups for all periods analyzed. In addition, no remarkable differences were noticed in core binding factor 1 or vascular endothelium growth factor immune expression. CONCLUSION: Taken together, these results show that using a biologic membrane does not improve bone repair induced by bovine HA, as shown by histopathologic and immunohistochemical analyses.

Immunoexpression of Cbfa-1/Runx2 and VEGF in sinus lift procedures using bone substitutes in rabbits.

OBJECTIVES: To analyze and compare the expression of core binding factor-1 (Cbfa-1)/Runx2 and vascular endothelium growth factor (VEGF) in sinus lift procedures using bovine hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP). MATERIAL AND METHODS: Twenty-four male rabbits that had undergone bilateral sinus lift procedures were divided into three groups, according to the sinus filling material: Group 1: autogenous bone graft; Group 2: bovine HA; and Group 3: beta-TCP. All groups were sacrificed after 7, 14, 30 and 60 days, for microscopic, histomorphometry and immunohistochemistry analysis. RESULTS: Microscopic analysis showed a similar bone repair pattern between the tested groups. New bone formation, soft and medular tissue, remaining material or particulate bone graft area were obtained by histomorphometric analysis. After 14 days, statistically significant differences in new bone formation were found between Group 1 (27.76+/-7.8) and Groups 2 (14.22+/-3.2) and 3 (11.1+/-7.7). After 30 days, statistically significant differences (P<0.05) were detected in bone formation between Groups 1 (31.39+/-36.5) and 2 (14.13+/-3.2). The last period showed improved bone formation in Group 2. Also, Group 2 showed higher Cbfa-1/Runx2 immunoexpression when compared with Group 3. No remarkable differences were observed in VEGF immunoexpression among groups. CONCLUSION: Taken together, both biomaterials allowed bone tissue growth in a conductive pattern and did not interfere with bone remodeling in the late period, with a slight improvement in bone tissue formation when using HA, confirmed by marked expression of Cbfa-1 at initial periods.

Fibrovascularization and osteogenesis in high-density porous polyethylene implants.

High-density porous polyethylene (HDPP) has been extensively used in craniofacial reconstructions with high-level success and minimal complications. It is known for its biocompatibility and satisfactory stability in the receptor bone area, presenting only a few reports of mobility and infection. In the current study, attention was given to the interface area between HDPP and bone surface to analyze fibrous and bone tissue formation and ingrowth into the pores of the material placed in the mandible of rabbits. Twelve male New Zealand rabbits underwent surgical procedure to receive bilateral HDPP implants in buccal face of dentate mandibular alveolar process, fixed with titanium screws. After 7, 14, 45, and 90 days, the animals were killed, and the specimens were retrieved for histologic and immunohistochemical analyses. No implant loss or infection was detected at the retrieval of the specimens. The microscopic analysis presented satisfactory integration of the material to the bone surface, with new bone formation from the receptor bed and inside the pores of the material, observed from the 15th day. After 90 days, remodeling bone and fibrous tissue was seen in the interface region. Among some of the pores, mature lamellar bone was present. Immunohistochemistry pointed out a moderate expression either to Core binding factor protein 1/RUNX2 or to vascular endothelial growth factor for early periods evaluated, that is, 7 and 15 days after surgery. These results confirm the osteoconductive behavior and high biocompatibility of the material, associated to its adequate immobilization, leading to its lifelong presence in human biologic system.

Bovine hydroxyapatite (Bio-Oss(®)) induces osteocalcin, RANK-L and osteoprotegerin expression in sinus lift of rabbits.

PURPOSE: The aim of this study was to analyze and compare the expression of osteocalcin, RANK-L, osteoprotegerin, in sinus lift procedures using bovine hydroxyapatite (HA). MATERIAL AND METHODS: Twenty four male rabbits underwent bilateral sinus lift procedures were distributed into two groups, according to the sinus filling material: Group 1) autogenous bone graft; and Group 2) bovine HA. All groups were sacrificed after 14 and 30 days, for microscopic and immunohistochemistry analysis. RESULTS: At 14 days after surgery, discrete osteogenesis was observed in the highly vascularized granulation tissue surrounding HA particles, as well as woven bone deposition on the biomaterial surface. Following 30 days, well organized bone trabeculas were seen surrounding the HA granules presenting areas of osteogenic activity. Morphometric findings did not show remarkable differences between groups. Bovine HA induced similar osteocalcin, RANK-L, osteoprotegerin immunoexpressivity when compared to autogenous bone graft group for both periods evaluated in this setting. CONCLUSION: Taken together, these data are consistent with the notion that HA has a similar biological behavior to autogenous bone graft in sinus lift of rabbits.