Influence of the bone graft materials used for guided bone regeneration on subsequent peri-implant inflammation: an experimental ligature-induced peri-implantitis model in Beagle dogs.

PURPOSE: We aimed to histologically evaluate the influence of bone materials used during guided bone regeneration (GBR) on subsequent peri-implantitis in an experimental ligature-induced peri-implantitis model in beagle dogs. METHODS: Bilateral mandibular premolars (PM2-4) were extracted from six beagle dogs. After 3 months, standardized bone defects (3 mm [mesio-distal width] × 2 mm [bucco-lingual width] × 3 mm [depth]) were created in the experimental group, with simultaneous dental implant placement at the center of the defects. The defects were randomly filled with either autograft (AG) or deproteinized bovine bone mineral (DBBM) and covered with a collagen membrane. In the control group, implant fixtures were placed without creating an intrabony defect. After 3 months, a healing abutment was placed. Four weeks later, a 3-0 silk thread was ligated around the implants to induce peri-implantitis. After 4 weeks, the specimens were dissected and histologically examined. RESULTS: There were no clinical findings of inflammation until silk thread ligation. Four weeks after the onset of peri-implantitis, gingival redness and swelling were seen with mild resorption of the peri-implant bone on dental radiographs. There were no significant differences between the AG, DBBM, and control groups for the following parameters: bone-to-implant contact, distance from the implant shoulder to the base of the bone defect, area of bone defect, and area of new bone. CONCLUSIONS: Within the limitations of this study, it can be concluded that peri-implant tissues after GBR using AG and DBBM underwent the same degree of bone resorption by peri-implantitis as the no defect group.

Ridge reconstruction in damaged extraction sockets using tunnel ß-tricalcium phosphate blocks: A 6-month histological study in beagle dogs.

OBJECTIVE: The present study aimed to evaluate the histological outcome of tunnel ß-TCP blocks grafting in extraction sockets missing the buccal bone wall, after 6 months of healing. BACKGROUND: Tunnel ß-tricalcium phosphate (ß-TCP) blocks made of randomly organized tunnel-shaped ß-TCP ceramics appeared promising for alveolar ridge preservation in tooth extraction sockets missing the buccal bone, in a previous study in dogs, with a 2-month healing time. METHODS: In six beagle dogs, the maxillary first premolars were extracted and the buccal bone was surgically removed to create bone defects of 4 mm (mesio-distal) × 5 mm (apico-coronal) × 4 mm (bucco-palatal). Thus, extraction sockets missing the buccal bone plate were grated with tunnel ß-TCP blocks (test) or left empty for spontaneous healing (control). Histology/histomorphometry was performed after 6 months of healing. RESULTS: The horizontal bucco-palatal width of the alveolar ridge was significantly greater at test sites than at control sites. The amount of mineralized tissue was greater at test sites (57.8% ± 11.1%) than at control sites (28.9% ± 8.5%), while the amount of connective tissue was significantly greater at control sites (41.7% ± 6.4%) than at test sites (19.6% ± 9.2%). No significant difference was found between sites in terms of basic multicellular units and bone marrow. Residual ß-TCP at test sites was 5.8% ± 3.2%. CONCLUSION: Grafting with tunnel ß-TCP block significantly limited the resorption of the alveolar ridge at extraction sockets missing the buccal bone compared with sites left to heal spontaneously, even after 6-month follow-up.

Histological healing after nonsurgical periodontal treatment with enamel matrix derivatives in canine experimental periodontitis.

The histological outcomes after nonsurgical periodontal treatment with enamel matrix derivatives (EMD) remain controversial. The present study evaluated periodontal wound healing after scaling and root planing (SRP) with subgingival application of EMD for treatment of experimental periodontitis. Periodontal breakdown was induced by applying silk ligatures around mandibular third and fourth premolars of six beagle dogs until radiographic bone loss progressed to approximately half of the root length. Probing pocket depth (PPD) and clinical attachment level (CAL) were proximally measured 2 weeks after ligature removal (baseline). Mesial and distal surfaces of the experimental teeth were subjected to SRP and randomized using a split-mouth design to subgingival application of EMD (test) or normal saline (control). PPD and CAL were re-evaluated at 11 weeks. Animals were sacrificed at 12 weeks for histological analyses. No significant differences were observed in PPD and CAL between both groups at baseline and at 11 weeks. Histologically, test sites exhibited a greater amount of new cementum than that did the control sites (p < 0.01). Moreover, the control sites revealed increased epithelial downgrowth compared with the test sites: (p < 0.05). On the other hand, no intergroup differences were detected in terms of bone position, connective tissue attachment, gingival recession, and planed root length. This study suggested that EMD has an increased potential to support formation of new cementum with decreased epithelial downgrowth when used as an adjunct to nonsurgical periodontal treatment.

Histological Changes in Alveolar Bone After Onlay Augmentation Using the Casing Method.

Numerous studies on alveolar bone augmentation have been reported. However, it remains challenging to obtain favorable new bone, especially for onlay bone augmentation. For successful onlay bone augmentation, it is necessary to use a graft material with high bone-forming activity and wound stabilization. We performed onlay bone augmentation on the buccal surface of mandibular alveolar bone in dogs, using a polyethylene terephthalate (PET) case (Casing method). The aim of this study was to histologically examine the feasibility of Casing method for external onlay bone augmentation. Beagle dogs were selected for this study. At 12 weeks after tooth extraction, a PET case was placed on the buccal surface of mandibular alveolar bone and filled with a mixture of hydroxyapatite and ß-tricalcium phosphate (ß-TCP) particles (volume ratio 1:1) impregnated with crushed autogenous bone (superfine bone powder) suspended in plasma. At 4, 8, and 16 weeks after bone graft, nondecalcified sections were histologically examined. At 4 weeks, new bone formation on the particle surfaces was observed on the original bone side of the PET case. At 16 weeks, bone formation was observed in almost all areas inside the case. The percentage of the augmented area (including new bone and particles surrounded by new bone; was significantly greater at 16 weeks (85.7% ± 6.0%) than at 4 weeks (10.5% ± 4.8%) or 8 weeks (69.6% ± 15.6%). The results of this study suggest that onlay bone augmentation using the Casing method has considerable potential to yield histologically favorable new bone formation. Anat Rec, 301:1148-1158, 2018. © 2018 Wiley Periodicals, Inc.

Implant Insertion into an Augmented Bone Region Using the Canine Mandible Augmented by the "Casing Method".

The purpose of this study was to examine the efficacy of bone augmentation using the "Casing Method," which enables large-scale osteogenesis, and the feasibility of using the augmented bone in dental implants. Three Beagle dogs were used. After tooth extraction, a polyethylene terephthalate case (20 mm × 5 mm × 10 mm) was placed on the buccal surface of the mandible. A mixture of hydroxyapatite and beta-tricalcium phosphate (volume ratio = 1:1) was infiltrated into a suspension of autologous superfine bone powder and plasma, and the resulting mixture was packed into the case. After 16 weeks, the implant was inserted into the augmented bone and the original bone. Specimens of the mandible were collected at 2, 4, 8, and 16 weeks after implant insertion, and undecalcified sections were prepared. The integration of the implant into the surrounding bone tissue was observed histologically. Favorable bone formation was observed in the regions where bone augmentation was performed. The space between the cut bone surface and the implant was filled with newly formed bone in both the augmented and original bone regions. In addition, there was higher bone density in the augmented bone than that in the original bone at the coronal half of the implant at 16 weeks. As a result, bone-to-implant contact was significantly higher in the augmented bone region than in the original bone region. These results suggest that bone augmentation surgery using the "Casing Method" is an effective technique for expanding the application of dental implants. Anat Rec, 301:892-901, 2018. © 2018 Wiley Periodicals, Inc.