Immunohistochemical comparison of lateral bone augmentation using a synthetic TiO2 block or a xenogeneic graft in chronic alveolar defects

Abstract

Objectives: To evaluate osteogenic markers and alveolar ridge profile changes in guided bone regeneration (GBR) of chronic noncontained bone defects using a nonresorbable TiO2 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: TiO2 block: TiO2 -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 (α-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 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 with DBBM and a collagen membrane or a collagen membrane alone.

Keywords: animal experimentation; bone regeneration; bone substitutes; guided tissue regeneration; immunohistochemistry; xenografts.

Conflict of interest statement

Haugen and Ellingsen hold patents for the technology for the TiO2 bone graft substitute (EP Patent 2121053, US Patent 9629941 US Patent App. 14/427901, US Patent App. 14/427683, and US Patent App. 14/427854). The rights for these patents are shared between the University of Oslo and Corticalis AS. Haugen and Ellingsen are shareholders and board members of Corticalis AS. The other authors report no conflicts of interest related to this study.

© 2022 The Authors. Clinical Implant Dentistry and Related Research published by Wiley Periodicals LLC.

Figures

FIGURE 1

(A) Timeline of the study design. (B) Guided bone regeneration (GBR) procedure on noncontained defects. Showing the anterior defect with deproteinized bovine bone mineral particulates, middle defect with a TiO2 block secured with a fixation screw and the empty posterior defect. Cortical perforations were performed at all recipient sites. All sites were covered with a collagen membrane stabilized by pin fixation.

FIGURE 2

Illustrations of the different regions of interest (ROIs) analyzed. ROItot showing a TiO2 sample with osteocalcin stain, ROI400 μm showing a deproteinized bovine bone mineral (DBBM) sample with collagen stain and ROI40 μm showing a negative control sample with osteopontin stain. Area with graft material was excluded. Box plots with statistical significance denoted by asterisks: *p < 0.05, **p < 0.01, ***p < 0.001. α‐SMA, alpha‐smooth muscle actin

FIGURE 3

(A) Deproteinized bovine bone mineral (DBBM) particulates seen as light green, mineralized bone in dark yellow, and unmineralized collagen in bright yellow. Percentage of collagen in region of interest (ROI)tot (B), ROI400 μm (C) and ROI40 μm (D). Statistical significance denoted by asterisks: *p < 0.05. 4 W, 4 weeks; 12 W, 12 weeks

FIGURE 4

(A) TiO2 group. Mineralized bone, including deproteinized bovine bone mineral (DBBM) particulates, stained black by Von Kossa/Van Gieson, while TiO2 appeared dark gray to black. An extracellular matrix is stained pink within the TiO2 scaffold and presents less intensity than the surrounding soft tissue and epithelium. Some voids from fracture and tearing of the scaffold are seen. Note migrated DBBM particulates at the bottom of the defect. Percentage of extracellular matrix in region of interest (ROI)tot (B), ROI400 μm (C), and ROI40 μm (D). Statistical significance denoted by asterisks: *p < 0.05, ***p < 0.001

FIGURE 5

(A) Osteoclast in a Howship lacuna, (B) Double asterisks denote statistical significance (p < 0.01). DBBM, deproteinized bovine bone mineral; TRAP, tartrate‐resistant acid phosphatase

FIGURE 6

(A) Superimposed stereolithographic images of TiO2 sample 4 weeks after guided bone regeneration. The baseline in purple and 4 weeks healing in green. Area difference in ROI is illustrated in yellow. Shown distance from the alveolar crest divides the top, mid, and low segments. (B) Area differences for alveolar contour. Statistical significance denoted by asterisks: *p < 0.05, **p < 0.01, ***p < 0.001. DBBM, deproteinized bovine bone mineral