Horizontal Bone Augmentation With Autogenous and Collagenated Xenogeneic Bone Blocks: A Split-Mouth Prospective Clinical, Tomographic, and Histological Pilot Study
The aim of this study was to compare the clinical, tomographic, and histological performance of collagenated xenogeneic bone blocks (CXBB) in horizontal bone augmentations for implant placement. Five patients with an absence of the 4 upper incisors and an HAC 3 horizontal bone defect, with a remaining of 3 to 5 mm, underwent a bone-grafting procedure with CXBB (test group [TG], n = 5) and autogenous graft (control group [CG], n = 5), with one type of graft used on the right side and other type on the left side. Changes in bone thickness and density (tomographic evaluation), levels of complications (clinically), and distribution pattern between mineralized and nonmineralized tissue (histomorphometrically) were analyzed. Tomographic analysis showed a horizontal bone increase of 4.25 ± 0.78 mm in the TG and 3.08 ± 0.8 mm in the CG between baseline and 8 months postoperatively (P < .05). The horizontal loss between the day of installation of the blocks and 8 months postoperatively was 1.02 ± 0.39 mm for the TG and 1.10 ± 0.71 mm for the CG (P > .05). With regard to bone density, the TG blocks right after installation had 440.2 ± 89.15 HU, and after 8 months, the region reached 730.7 ± 130.98 HU, representing an increase of 29.05%. For the CG blocks, bone density increased from 1052.2 ± 398.35 HU to 1222.5 ± 453.28 HU, representing an increase of 17.03%. The increase in bone density was significantly higher in the TG (P < .05). Clinically, no cases of exposure of the bone blocks and no failure of incorporation were observed. Histomorphometrically, the percentage of mineralized tissue was lower in the TG than in the CG (48.10% ± 2.88% and 53.53% ± 1.05%, respectively), and the opposite was verified for the levels of nonmineralized tissue (52.79% ± 2.88% and 46.47% ± 1.05%, respectively; P < .05). The use of CXBB achieved higher levels of horizontal gain, with lower bone density and lower levels of mineralized tissue when compared with the use of autogenous blocks.

(a) Bone defect. (b) Fixing the blocks. (c) Filling the spaces with particulate graft. (d) Covering with collagen membrane.

(a) Appearance of the graft blocks 8 months after first-stage surgery. (b) Installation of implants in the region of the upper lateral incisors.

Illustration of a tomographic section of the maxilla, where the presence of the graft fixation screw is noted, and from it the parameters for measuring bone thickness and density are created.

(a) T1 (baseline) of the control group. (b) T1 (baseline) of the test group. (c) T2 (after 8 months) control group. (d) T2 (after 8 months) test group.

Representative photomicrographs of the histological slides analyzed by histomorphometry stained by hematoxylin-eosin at 40× magnification showing the presence of mineralized tissue and nonmineralized tissue in the (a) control group and (b) test group.

Representative photomicrographs of the histological slides analyzed by histomorphometry stained by hematoxylin-eosin at 100× magnification, showing the presence of mineralized tissue (yellow arrows) and nonmineralized tissue (asterisks) in the (a) control group and (b) test group.

Clinical aspect of the final rehabilitation of the anterior maxillae.
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