Our study measured the Hounsfield density (HU) using a tool ofthe SimPlant software. Hounsfield unit is a use- ful diagnostic tool for quantitative measurement ofbone
density; 29 however, it can be commonly acquired from MSCT. There have been studies proposing the use of HU asa measure ofbone density from the CBCT images but they concluded that the HU values obtained in CBCT were different from those in MSCT. In particular, Silva et al 30 evaluated the validity ofthebone density value in HU from CBCT images compared with MSCT images. They concluded that the use ofthe HU scale on CBCT images was not a reliable method. Even though the technical improvement of CBCT and the widespread usage of new software enabling “correction” factors would be required for evaluationofbone density as HU, our study evaluated the HU using the SimPlant software, and the HUs were 433±146, and ranging from 110 to 869 for the cancellous bone and 1,087±142, ranging from 608 to 1,349 for the cortical bone. These results were not different from the study of Yavuz et al, 27 which reported a mean Hounsfield density of 958.95±98.11 HU for cortical-cancellous bone.
However, the survival rate was 100 %, and success rate was 95 % in group 1. In the cases of mucous retention cyst, the mucus ofthe maxillary sinus was aspirated prior to sinus membrane elevation. This could decompress in- ternal pressure, reduce the size ofthe cyst, and decrease the possibility of laceration ofthe Schneiderian membrane during sinus membrane elevation. Therefore, the sinus membrane has to be elevated carefully from the bony floor using antral curette . In this study, however, there were five cases of eight cases in which the sinus mem- brane was perforated and closed by a collagen membrane and the sinus augmentation was done successfully. In diagnosis of mucous retention cyst, there is limitation using radiographs. The size ofthe lesion of mucous reten- tion cyst was not large enough to be found in radiographs, and the mucus should be aspirated to confirm the diagno- sis. To rule out the POMC, the patients were asked whether they had a surgery related to the maxillary sinus, and to rule out pseudocyst, it was checked whether the epithelial cells surround the lesion. And also, mucocele was ruled out through the character and size ofthe lesion.
In the present study we assessed the effectiveness of three types of calcium phosphate synthetic block bonegraft material in bone regeneration using defects in the rabbit calvarium. Rabbit cranial defect models have been used in numerous studies for evaluating newly developed biomaterials due to the adequate amount ofbone marrow. An 8-mm defect is known to be smaller than the critical defect size in rabbits for evaluating reossification, but has been suggested asa useful defect model for determining the effects of osteoinduction. The use of four 8-mm defects allowed comparison of an early-phase healing response for several materials, while avoiding individual variations. In the present study, the late and intermediate healing responses were analyzed at 8 and 4 weeks postsurgery, respectively.
Since the lack of alveolar bone is one ofthe most prevalent and difficult problems to address in implant surgery, many methods have been developed and used. In the past, autogenous onlay bonegraft was mainly used for the impro- vement of horizontally and vertically shrunken alveolar ridge. Note, however, that it needed additional surgery on the donor site, and predicting the result was difficult since bone resorption varied according to the collection area 5 . Recently, the trend of research reports on the selection of standard treatment for knife-edge ridge has been changing slightly 7,8 . Simion et al. 3 performed vertical bone augmentation with demineralized freeze-dried bone or autogenous bone chip and non-resorbable membrane and reported a good result after 1-5 years’ follow-up. Another paper reported that horizontal bone augmentation with the mixture of autoge nous bone and xenobone covered with resorbable membrane resulted in 4.6 mm bone gain. Another paper reported 3.6 mm bone gain when only xenobone was used in horizontal bone augmentation 7 . Yet another report stated that vertical bone augmentation using xenobone block type on 9 patients yielded cases except one, with titanium mesh, resorbable membrane
J Korean Assoc Oral Maxillofac Surg 2013;39:156-160. https://doi.org/10.5125/jkaoms.2013.39.4.156
This correction is being published to correct authorship list. The fourth author listed in the above article, who did not meet au- thorship criteria of Journal ofthe Korean Association of Oral and Maxillofacial Surgeons, should be removed.
A slowly resorbable biomaterial might be suitable in sub-sinusal bone augmentation for preventing the re-expan- sion process and for augmenting the density ofthe regen- erated tissues. Bovine HA seems to be the most efficient fillers for 3 dimensional stability of sub-sinusal bone aug- mentation. 48 In this study, AutoBT and Bio-Oss showed similar healing pattern, excellent graft volume maintenance and active new bone formation, in microCT and histomor- phometric evaluationof biopsy specimen 4 months after graft procedure. So, if it was applied for sinus bonegraft, it would be useful material struggling repneumatization against intra-sinus pressure. Bone formation was found sur- rounding both enamel and dentin portion of AutoBT material. New bone bridges between graft materials were also detected in AutoBT group. Also newly-formed and matured lamellar bone was detected surrounding AutoBT material, osteoblasts covering newly-formed bone accumu- lated osteoid.
known to depend on various factors, including the microstructure ofthegraft, the movement ofthegraft, the location ofthebonegraft, and the preparation ofthe recipient bone bed.
Immobilization ofthegraft was found to be a crucial factor for bone ingrowth. Bone ingrowth occurred in the presence of small movements, while excessive movements could result in fibrous tissue ingrowth instead . The onlay bone block grafting technique used in this study also represented a challenging situation, since thegraft was less exposed to the recipient site vasculature and under the greater forces from the surrounding soft tissues than is the case for inlay grafting [26,28]. Decortication ofthebone bed was reported to accelerate bonegraft integration with the recipient bed and to induce greater new bone formation at the interface between thebonegraft and recipient bed by increasing the vascular supply . Osteogenesis involves the recruitment of mesenchymal stem cells to the site where they differentiate into osteoprogenitors and osteoblasts upon stimulation by local factors . Decortication ofthebone bed prior to bone grafting was reported to exert a significant influence on the quantity of new tissue formation and osteogenesis for bonegraft integration . Decortication ofthebone bed has been found to provide a vascular supply and to place thegraft in direct contact with mesenchymal stem cells, osteogenic cells, and cells involved in neovascularization, as well as exposing thegraft to the osteoinductive and osteogenic factors present in the blood . Therefore, a decorticated bone bed led to greater new bone formation in thegraft than a non-decorticated bed. In this study, although the porous polyethylene block was stabilized with a titanium screw, it might still have been rotated or moved by forces exerted by the soft tissue during mastication. Together with the low vascularization access ofthe onlay grafting and the non
β-TCP: 20/80) had a higher resorption rate, higher percentage ofgraft surface coverage throughout the study period, and more bone formation that was similar to autografts during the initial healing phase than BCP (HA/ β-TCP: 80/20 or 60/40).
During the total 52-week healing time, the total resorption of BCP(HA/ β-TCP: 80/20 or 60/40), which has a slow resorption rate, was not complete. However, qualitative differences were observed among BCPs with different HA/ β-TCP ratios after 4 weeks.
With successful extraction of growth factors and bone morphogenic proteins (BMPs) from mammalian teeth, many researchers have supported development ofabonesubstitute using tooth-derived substances. Some studies have also expanded the potential use of teeth asa carrier for growth factors and stem cells. A broad overview ofthe published findings with regard to tooth-derived regenerative tissue engineering technique is outlined.
Considering more than 100 published papers, our team has developed the protocols and techniques for processing ofbonegraft material using extracted teeth. Based on current studies and studies that will be needed in the future, we can anticipate development of scaffolds, homogenous and xenogenous tooth bone grafts, and dental restorative materials using extracted teeth.
safety 11 . Jensen et al. 12 compared thebone healing achieved using autografting, anorganic bovine bone-derived mineral (ABBM), and synthetic b-tricalcium phosphate (b-TCP) in intraosseous defects in the mandible of minipigs. Autografting resulted in faster bone regeneration than grafting with either ABBM or synthetic b- TCP in the early healing phase. Although newly formed bone ultimately regenerated in all defects after 8 weeks regardless ofthegraft material used, autografting resulted in increased osseous maturity during all healing periods. Other studies have also shown that autogenous bone can induce faster and more mature bone regeneration in the initial healing period of lateral ridge augmentation 13,14 . In spite of these advantages, the unpredictable resorption rate, limited availability, and patient morbidity limit its common use. Bone substitutes may overcome these potential shortcomings, and a good solution when autogenous bone is harvested may be combining that harvested bone with an osteoconductive bonesubstitute 15 .
Summary and discussion
The maxillary sinus is connected to the nasal cavity through one or two inferior nasal meatus in the upper 1/3 ofthe internal wall ofthe maxillary sinus. If the maxillary sinus is elevated excessively, this area may be exposed, and care must be taken to avoid this. After birth, the maxillary sinus enlarges continuously and comes to occupy much ofthe maxilla. At adolescence, the maxillary sinus extends from the canine to the 3rd molar, and from the floor ofthe orbit superiorly to the root ofthe maxillary canine inferiorly. Consequently, the maxillary sinus interferes with implant placement near the maxillary canine. Therefore, implant placement requires elevation ofthe maxillary sinus mucosa. In addition, with loss ofthe maxillary canine, the alveolar bone is resorbed progressively from the buccal side, decreasing the height ofthe alveolar bone and shifting the crest ofthe alveolar bone toward the midline. Together with the pneumatization ofthe maxillary sinus, this makes implant placement difficult 12) .
alveolar bone. 8,9 However, titanium graft material cannot be used in the esthetic zone due to its unique metallic shade. 10
Among the materials that can be used asbone grafts, zirconia is being studied asa material to replace existing alloplastic bone grafts and has shown excellent biological compatibility. Yttria-stabilized tetragonal zirconia polycrys- tals (Y-TZP) has excellent mechanical strength and biologi- cal compatibility. 11-20 Y-TZP is a non-absorbable material, 21 and with its color similar to those of natural teeth and alve- olar bone, it can be used asbonesubstitute material in the anterior region of mouth and thin gingiva where esthetics are required. 22
Material and Methods: Six minipigs were used in this study. Four molars were extracted in the right mandibular dentition and sent to the Korea Tooth Bank for fabrication of autogenous tooth bone. Ten days later, each extraction site was implanted with MS Implant Narrow Ridge 3.0x10mm fixture (Osstem, Seoul, Korea) after standardized 2mm-sized artificial vertical bony defect formation. Pineappleshaped Root-On type autogenous tooth bones were applied to the vertical defects around the neck area ofthe posterior three fixtures and the fore-most one was not applied with autogenous boneasa control group. Each minipig was sacrificed at 4, 8, 12 weeks after fixture installation and examined radiologically and histologically. Histological evaluation was done under light microscope with Villanueva osteochrome bone staining with semi-quantitative histomorphometric study.
There were some limitations of this study. This study is neither a prospective study nor a consecutive case series. The prosthetic pro- cedure was not standardized. Therefore, long-term follow-up stud- ies including a histologic evaluation are necessary. Additional ran- domized controlled trials are also necessary to evaluate the longi- tudinal effect of this new DBBM. Our results show that the new DBBM is useful for a maxillary sinus graft procedure. Clinically good healing responses and reliable results were shown for a mean fol- low-up period of 43.3 months.
The author started the paragraph with the preparation of PRF, however, described the protocol for PRP, continued by saying that “coagulated preparation of 0.3 mL of PRF was obtained by its combination with 0.1 g of calcium chloride” and then finish by saying that
“then graft material was mixed with the coagulated PRP preparation.”
corresponding cell surface receptors, and the extracellular matrix. 8,9 The molecular mechanism of such regeneration is caused by osteogenic proteins that belong to the TGF-β (transforming growth factor β) subgroup. Among those pro- teins, BMP has particularly drawn attention asa potent mate- rial inducing bone differentiation. 10 There are more than 20 BMP subgroups, among which BMP-2 has been proven via preclinical and clinical studies to be useful for therapeutic purposes regarding to bonegraft in dentistry. 11,12 BMP-2 promotes the proliferation of osteoblasts from mesenchymal stem cells by regulating the essential factors for the osteoinduction-regen- erating bone structure, and enhances osteogenesis by assisting the biosynthesis ofthebone matrix. 13 Sykaras et al. 14 report- ed that BMP-2 was effective in titanium implant osseointegration.
Key words: Bone graft; Bone regeneration; Platelet rich fibrin
The relationship between pulpal and periodontal disease was first described by Simring and Goldberg in 1964. 1 In many cases it is easy to establish diagnosis, but there are certain cases, where situation becomes more complex, especially when it combines with periodontal disease. It becomes essential to correct periodontal defect simultaneously in these cases to prevent recurrence, and to improve functional status ofthe tooth. 2 Various treatment modalities have been proposed earlier for the treatment of endo-perio involvement including open flap debridement, root resection and retrograde filling, where healing is by scar. 3 Since this is not ideal, newer approaches such as regenerative procedures like guided tissue regeneration (GTR), bone grafts and growth factors that aim to restore lost tissue have been introduced. Platelet rich fibrin (PRF) enriched with platelets and growth factors promotes periapical tissue regeneration and healing. This case report presents an attempt to evaluate the healing kinetics ofthe combination of PRF and alloplastic bonesubstitute (Bioactive glass) as opposed to using these materials alone.
본 실험에서는 미니돼지를 사용하였는데 그 이유는 사람 과 미니돼지의 치아성분 및 치조골의 기본적인 구성성분 이 유사함이 알려져 있으며 여러 이유로 미니돼지는 치과 영역에서 줄기세포연구 및 그 외 골이식 실험시 많이 사용 되는 동물 중 하나이기 때문이다 21 . 본 실험의 결과 자가 치 아를 이용한 골이식재를 이식한 실험군에서 4주군의 초기 골형성능이 우수함을 보였으며 초기에 이식한 자가 치아 뼈 골이식재는 점차적으로 흡수되고 새로운 골로 치환되 며 새로 형성된 골은 남아있는 치아이식재 주위로 긴밀한 결합을 보임을 관찰할 수 있었다. 그에 반해 대조군인 합성 골 이식재는 흡수가 느리며 남아있는 이식재 주위로 신생 골이 형성되기보다 기존골 변연 부위에서 더 많이 관찰되 는 경향을 보였다. 상대적으로 실험군에서 초기 골형성이 더 활발한 것을 관찰할 수 있었고 새롭게 형성된 골량도 더 많음을 관찰할 수 있었다. 개체수가 많지 않아 비모수 통계 처리 결과 통계적 유의성이 없었던 점, 미니돼지의 치아에 대한 자세한 분석이 이루어지지 않았으며 장기간 추적 조 사가 이루어지지 않은 점, 골 결손부를 형성하고 치유를 기 다렸다가 만성적 골 결손부(chronic bony defect) 부위에 골 이식을 하는 실험이 아니라는 점 등이 이 연구의 한계점으 로 남아있다. 자가 치아뼈 이식재의 골유도능을 확실히 평 가하기 위한 추가적인 실험 연구들이 필요하지만 현재까 Table 1. The ratio of new bone to bone defect in each group
Purpose: This retrospective study compares the amount ofbone resorption around implants between an autogenous tooth bonegraft (AutoBT) and a synthetic bonegraft after abone- added crestally approached sinus lift with simultaneous implant placements.
Methods: In all, 37 patients participated in this study. Seventeen patients were grouped as group I and underwent an AutoBT-added sinus lift using the crestal approach. The remaining 20 patients were grouped as group II and underwent synthetic bone grafting. Both groups received the implant placements simultaneously. Of the 37 participating patients, only 22 patients were included in the final results: Eleven patients of group I and 11 patients of group II. Before the surgery, the distance from the alveolar crest to the sinus floor was mea- sured using panoramic radiography. After the surgery, the distance was measured again from the neck ofthe implant thread to the most superior border ofthe added graft materials.