Layered approach with autogenous bone and bone substitute for ridge augmentation on implant dehiscence defects in dogs.

OBJECTIVES: This study compared the efficacies of different layered approaches using autogenous bone and synthetic bone substitute for ridge augmentation on implant dehiscence defects in dogs. MATERIALS AND METHODS: Right mandibular second, third, and fourth premolars and the first molar were extracted, followed by standardized one-wall defect preparation in five dogs. After a healing period of 12 weeks, three implants (Implantium(®) ) were installed. Each of the three implant dehiscence defects was grafted with a different material as follows: (i) synthetic bone substitute combined with collagen (SBC; SBC group), (ii) inner autogenous bone layer and outer SBC layer (IAB group), and (iii) inner SBC layer and outer autogenous bone layer (OAB group). The grafted sites were covered with a resorbable collagen membrane. Quantitative and qualitative analyses of the subsequent bone regeneration were performed at 12 weeks postoperatively. RESULTS: The dome-like augmented shape was relatively well maintained in the IAB and OAB groups, while the graft particles in the SBC group were dispersed. The bone-to-implant contact values tended to be significantly higher in the OAB group (49.51%) than in the SBC (36.58%) group. The amounts of newly formed bone within an area designated as 1 × 3 mm (width × height) from the implant platform in the IAB, OAB, and SBC groups were 35.59%, 28.10%, and 16.71%, respectively. CONCLUSION: Application of the layered approach using autogenous bone and synthetic biomaterial resulted in substantial new bone formation and volume maintenance on implant dehiscence defects, irrespective of the position of the autogenous bone layer.

The efficacy of BMP-2 preloaded on bone substitute or hydrogel for bone regeneration at peri-implant defects in dogs.

OBJECTIVES: The objective of this experiment was to test whether or not a synthetic bone substitute (SBS) was more effective than a polyethylene glycol hydrogel as a carrier material for bone morphogenetic protein-2 (BMP-2) when attempting to regenerate bone. MATERIAL AND METHODS: Two identical, box-type dehiscence defects (4 × 4 mm buccolingually and apicocoronally, and 8 mm mesiodistally) were surgically prepared on buccal sides of the left and right edentulous ridge in five beagle dogs. Following implant placement, the defects either received (i) no graft, (ii) SBS+hydrogel, (iii) SBS+BMP-2 loaded hydrogel, and (iv) BMP-2-loaded SBS+hydrogel. The animals were euthanized at 8 weeks postsurgery. Radiographic and histomorphometric analyses were performed. RESULTS: The hydrogel alone was not able to stabilize the grafted bone particles at 8 weeks, and SBS+hydrogel group did not significantly differ from the control group in all volumetric measurements. On the other hand, extensively regenerated new bone was connected with most of the remaining SBS particles in the BMP-2 groups. The BMP-2 groups exhibited significantly greater new bone formation (10.65 mm(3) and 1.47 mm(2) in the SBS+BMP-2-loaded hydrogel group; 14.17 mm(3) and 0.93 mm(2) in the BMP-2-loaded SBS+hydrogel) than non-BMP-2 groups (1.27 mm(3) and 0.00 mm(2) in the control group; 2.01 mm(3) and 0.19 mm(2) in the SBS+hydrogel group) in volumetric and histomorphometric analyses (P < 0.001). However, there were no significant differences between both BMP-2 groups. CONCLUSION: BMP-2 could yield enhanced bone regeneration in the critical-size peri-implant defects regardless of whether SBS or hydrogel is used for preloading, although the outcomes seem to be more reproducible with BMP-2 preloaded on SBS.

Secondary stability of microthickness hydroxyapatite-coated dental implants installed without primary stability in dogs.

OBJECTIVES: The objective of this study was to evaluate the secondary stability of microthickness hydroxyapatite (HA)-coated implants placed without primary stability in dogs. MATERIALS AND METHODS: A total of 48 implants were placed in six dogs. The groups were divided according to the absence or presence of primary stability and healing periods (4 and 8 weeks). Two implants for histological analysis and removal torque test in experimental group were placed without primary stability, showing rotational movement. The other two implants in control group were placed with primary stability. Mechanical test values and histometric measurements were analyzed. RESULTS: The experimental group showed significant increase in a time-dependent manner, while the mean values of the control group were constant in the mechanical tests. The HA layer remained intact, and substantial bone fragments were attached on the surface of the retrieved implant. All implants appeared to be in intimate contact with the host bone and without any inflammation after both 4 and 8 weeks of healing in histology. CONCLUSION: The HA-coated implants exhibited mechanically and histometrically comparable osseointegration after 4 weeks of healing, regardless of primary stability, and the HA-coating layer demonstrated high resistance to exfoliation.

Effects of epigallocatechin-3-gallate on the healing of extraction sockets with a periapical lesion: A pilot study in dogs.

The aim of this study was to characterize the healing process of extraction sockets with a periapical lesion following immediate graft with collagenated bovine bone mineral (CBBM) soaked with epigallocatechin-3-gallate (EGCG). Following induction of periapical lesions in premolars in five dogs, treatment of extraction sockets was divided into three groups: control (no treatment) and two test groups, CBBM with or without EGCG. 3D reconstruction and superimposition of the digital images were used to measure the dimensional changes in alveolar ridge. Histologic specimen was evaluated in all groups. The horizontal ridge widths at 4-mm level were wider in both test groups (3.3 ± 1.7 mm in CBBM; 3.0 ± 1.7 mm in CBBM+EGCG) than in the control group (1.7 ± 2.4 mm). Fibrosis and limited new bone formation were observed in the apical regions of test groups; however, the extent of fibrosis was less in the CBBM+EGCG group. Within the limitations of this study, it was conjectured that adjunctive use of EGCG with CBBM can be a candidate biomaterial in grafting of extraction socket with periapical lesion. Bone regeneration at the coronal region of the CBBM grafted socket might not be influenced by the presence of a periapical lesion.