Various bone graft products are commercially available worldwide. However, there is no clear consensus regarding the appropriate bone graft products in different clinical situations. This review is intended to summarize bone graft products, especially alloplastic bone substitutes that are available in multiple countries. It also provides dental clinicians with detailed and accurate information concerning these products. Furthermore, it discusses the prospects of alloplastic bone substitutes based on an analysis of the current market status, as well as a comparison of trends among countries. In this review, we focus on alloplastic bone substitutes approved in the United States, Japan, and Korea for use in periodontal and bone regeneration. According to the Food and Drug Administration database, 87 alloplastic bone graft products have been approved in the United States since 1996. According to the Pharmaceuticals and Medical Devices Agency database, 10 alloplastic bone graft products have been approved in Japan since 2004. According to the Ministry of Health and Welfare database, 36 alloplastic bone graft products have been approved in Korea since 1980. The approved products are mainly hydroxyapatite, β-tricalcium phosphate, and biphasic calcium phosphate. The formulations of the products differed among countries. The development of new alloplastic bone products has been remarkable. In the near future, alloplastic bone substitutes with safety and standardized quality may be the first choice instead of autologous bone; they may offer new osteoconductive and osteoinductive products with easier handling form and an adequate resorption rate, which can be used with growth factors and/or cell transplantation. Careful selection of alloplastic bone graft products is necessary to achieve predictable outcomes according to each clinical situation.

Background:The alveolar ridge undergoes pronounced reduction in height and width following tooth extraction. This study aims to comparatively evaluate the potential for ridge preservation in extraction sockets with buccal bone deficiency of -tricalcium phosphate coated with poly lactide-co-glycolide ( -TCP/PLGA) and conventional particulate -TCP. Methods:In six beagles, maxillary first premolars were extracted after removal of their buccal bone plates. Standardized bone defects (4 [mesiodistal width] × 4 [buccopalatal width] × 5 [depth] mm) were created at the sites of extraction sockets and filled with -TCP/PLGA (test sites) or particulate -TCP (control sites). Microcomputed tomography, histologic, and histometric evaluations were performed 12 weeks post-surgery. Results:The test sites exhibited a significantly greater bone volume than the control sites (25.7 ± 2.14 versus 16.0 ± 3.3 mm 3 ), although no statistically significant difference was detected in bone material density (746.3 ± 23.9 versus 714.5 ± 37.0 g/cm 3 , respectively). Relative to the control sites, the test sites exhibited significantly greater alveolar-ridge coronal (2.0 ± 0.4 versus 1.1 ± 0.3 mm) and middle (2.9 ± 0.2 versus 2.1 ± 0.3 mm) horizontal widths and proportions of woven bone (50.3 ± 8.1% versus 38.0 ± 5.2%) and bone marrow (17.7 ± 6.6% versus 9.7 ± 4.1%) but a significantly lower proportion of connective tissue (10.7 ± 4.5% versus 18.3 ± 5.7%). Conclusion:Within the limitations of this study, the moldable -TCP/PLGA graft appears to exhibit a greater potential than the conventional particulate -TCP graft for ridge preservation of extraction sockets with buccal bone deficiency. K E Y W O R D Salveolar ridge augmentation, -tricalcium phosphate, biocompatible materials, dogs, osteogenesis, tooth extraction 1014

Background and Objective It is well known that recombinant human fibroblast growth factor‐2 (rhFGF‐2) signaling plays an important role in tissue repair and regeneration. rhFGF‐2 strongly binds to acidic gelatin via ionic linkages and is gradually released upon gelatin decomposition. On the other hand, the linkage between rhFGF‐2 and basic gelatin is so weak that most rhFGF‐2 is rapidly released from basic gelatin by simple desorption. Gelatin/β‐tricalcium phosphate (β‐TCP) sponges, which comprise 50 wt% gelatin and 50 wt% β‐TCP in a cross‐linked structure, can release rhFGF‐2 gradually owing to their electrical features. In a previous study, we reported that new bone height in the test group using rhFGF‐2 with acidic gelatin/β‐TCP sponges was significantly greater than that in the control group using acidic gelatin/β‐TCP sponges alone in a ridge augmentation model in dogs. However, whether these results depend on controlled release by the gelatin/β‐TCP sponges remains controversial. In this study, we evaluated the effects of controlled release by comparing acidic and basic gelatin/β‐TCP sponges with different isoelectric points (IEP) on ridge augmentation in dogs. Materials and Methods Twelve weeks after extraction of the maxillary second and third incisors of six dogs, critically sized saddle‐type defects (8 mm length × 4 mm depth) were surgically created bilaterally 2 mm from the mesial side of the canine. Acidic gelatin/β‐TCP sponges (IEP 5.0) soaked with 0.3% rhFGF‐2 were applied to the defect in the acidic group, whereas basic gelatin/β‐TCP sponges (IEP 9.0) soaked with 0.3% rhFGF‐2 were applied to the defect in the basic group. Twelve weeks after surgery, biopsy specimens were obtained and subjected to microcomputed tomography (micro‐CT) and histological analyses. Results New bone area detected by micro‐CT analysis was significantly smaller in the basic group than in the acidic group. New bone height calculated by histologic sections was significantly lower in the basic group than in the acidic group. The total tissue height was lower in the basic group than in the acidic group. However, the differences between both sites were not significant. Conclusions These findings suggest that in ridge augmentation of saddle‐type defects, controlled release of rhFGF‐2 induces notably more alveolar bone formation than does short‐term application of rhFGF‐2.

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We succeeded in the electrical polarization of β‐tricalcium phosphate (β‐TCP) granules and performed an unprecedented attempt to implant them into maxillary bone defects in canines to confirm their ability to facilitate new bone formation. Two holes were drilled into each maxilla half of a canine and filled with electrically polarized and nonpolarized β‐TCP granules (grouping assignment was decided randomly). The implanted specimens were dissected en bloc and used for microcomputed tomography (μCT) observations and histological analyses 4 and 8 weeks after the operation. New bone ingrowth in the bone hole progressed over time from the superficial layer of the cortex toward the inner cancellous bone. The percentage area of new bone in the bone hole, as measured by μCT in the sagittal plane, was significantly larger after 4 and 8 weeks, and that measured by H&E‐stained specimens in the transverse plane after 4 weeks was significantly larger in the polarized group than in the nonpolarized group. In addition to the structural stability and chemical characteristics of the β‐TCP granules, electrical stimulation bears influence not indirectly but directly on osteogenic and vessel cells, which might work cooperatively for the early initiation of the bone formation process.

Background and Objective Following tooth extraction, bone resorption is especially severe in cases complicated with buccal dehiscence bone defects. To minimize this, various bone graft materials have been used for alveolar ridge preservation. This study aimed to evaluate additional effects of the concomitant use of recombinant human fibroblast growth factor‐2 (rhFGF‐2) with β‐tricalcium phosphate (β‐TCP) on ridge preservation in a dehiscence defect model after tooth extraction in dogs. Materials and Methods The maxillary first premolars of six beagle dogs were extracted and dehiscence defects of 4 × 4 × 5 mm (mesio‐distal width × bucco‐palatal width × depth) were created. Bilateral defects were filled with β‐TCP combined with 0.3% (w/v) rhFGF‐2 (test sites) or the scaffold alone (control sites). Twelve weeks post‐surgery, histologic and histometric evaluations were performed. Results Morphological measurements using micro‐computed tomography revealed a significantly greater bone volume at the test sites (48.9 ± 9.06 mm3) than at the control sites (38.8 ± 7.24 mm3). Horizontal widths of the alveolar ridge at the coronal and middle position at the test sites (2.18 ± 0.71 mm, 2.93 ± 0.53 mm) were significantly greater than those at the control sites (1.47 ± 0.41 mm, 2.36 ± 0.45 mm, respectively). Regarding the histological parameters, the occupation rate of mineralized bone in the original defects was slightly higher at the test sites (44.07 ± 10.19%) than that at the control site (41.15 ± 6.56%). Conclusions These results indicate that the adjunct use of rhFGF‐2 with β‐TCP is effective for alveolar ridge preservation in fresh extraction sockets with dehiscence defects.

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.

ObjectiveThe present study aimed to evaluate the histological outcome of tunnel β‐TCP blocks grafting in extraction sockets missing the buccal bone wall, after 6 months of healing.BackgroundTunnel β‐tricalcium phosphate (β‐TCP) blocks made of randomly organized tunnel‐shaped β‐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.MethodsIn 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 β‐TCP blocks (test) or left empty for spontaneous healing (control). Histology/histomorphometry was performed after 6 months of healing.ResultsThe 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 β‐TCP at test sites was 5.8% ± 3.2%.ConclusionGrafting with tunnel β‐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.