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.