The use of solvent-preserved human and bovine cancellous bone blocks for lateral defect augmentation - an experimental controlled study in vivo.

BACKGROUND: The aim of this study was to compare new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material in laterally augmented alveolar bone defects using allogeneic, pre-treated and cleaned human bone blocks (tested in dogs, therefore considered to be xenogeneic), and pre-treated and cleaned bovine cancellous bone blocks, both with and without a collagen membrane in order to evaluate their augmentative potential. METHODS: Thirty-two critical size horizontal defects were prepared in the mandible of 4 adult foxhound dogs (8 per dog, 4 on each side). After 3 months of healing, the defects were laterally augmented in a split-mouth-design with either human (HXB) or bovine solvent-preserved bone blocks (BXB). Afterwards, defects were randomly covered with a bovine collagenous membrane (HXB + M, BXB + M). After a healing interval of 6 months, percentages of new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material were compared. RESULTS: Results showed little new bone formation of up to 3.7 % in human bone blocks (HXB 3.7 % ± 10.2, HXB + M 0.3 %± 0.4, BXB, 0.1 % ± 0.8, BXB + M 2.6 % ± 3.2, p = > 0.05). Percentages of fibrous encapsulation were higher in human bone blocks than in bovine bone blocks (HXB 71.2 % ± 8.6, HXB + M 73.71 % ± 10.6, BXB, 60.5 % ± 27.4, BXB + M 52.5 % ± 28.4, p = > 0.05). Resorption rates differed from 44.8 % in bovine bone blocks covered with a membrane to 17.4 % in human bone blocks (HXB 17.4 % ± 7.4, HXB + M 25.9 % ± 10.7, BXB, 38.4 % ± 27.2, BXB + M 44.8 % ± 29.6, p = > 0.05). The use of additional membranes did not significantly affect results. CONCLUSIONS: Within its limitations, results of this study suggest that solvent-preserved xenogenic human and bovine bone blocks are not suitable for lateral bone augmentation in dogs. Furthermore, defect coverage with a membrane does not positively affect the outcome.

[Vertical augmentation of the mandible using cortico-spongious xenoblocks. A histomorphometrical study in dogs]. / Vertikale Unterkiefer- augmentation mit kortikospongiösen Xenoblöcken. Eine histomorphometrische Tierstudie.

The aim of the present study was to histologically evaluate vertical ridge augmentation of the mandible using partially deproteinized cortico-spongious xenogenous blocks (XB) in dogs. Standardized acute-typed vertical lower jaw defects were surgically created in edentulous ridges of six foxhounds. Two similar bone blocks of 6 mm height were randomly inserted on each mandibular side and fixed with both a titanium implant and an osteosynthetic screw. Three groups were tested: i) XB (CS-Block bovin, Tutogen Medical) alone, ii) XB covered with a native xenogenous collagen membrane (XB+M) (Tutodent Membran, Tutogen Medical), and iii) autogenous blocks (AB), harvested during defect preparation from the ipsi- and contralateral side. After three months of submerged healing, the miniscrews were removed and replaced by secondary dental implants. In general, histological analysis revealed that augmentation of XB, used alone or in combination with a collagen membrane, did not lead to significant supracrestal bone apposition, resulting in means of 14 +/- 9% for XB and 25 +/- 9% for XB+M of basal ossification of the blocks. AB revealed significantly higher ossification rates of 46 +/- 16%. BIC rates were significantly higher for AB (70 +/- 15%) than for XB (26 +/- 15%) and XB+M (32 +/- 12%) (P < 0.05, Mann Whitney U-Test, respectively). Within the limits of the present study it was concluded that XB alone or in combination with a collagen membrane doesn't seem to be useful for vertical ridge augmentation procedures of the mandible.