巻号一覧
75 巻 (2008)
- 3 号 p. 143-
- 2 号 p. 93-
- 1 号 p. 1-
75 巻, 1 号
選択された号の論文の8件中1～8を表示しています
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藤田 紘一2008 年 75 巻 1 号 p. 1-5
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーThe masseter-muscle spindle is regarded as being highly adaptable to increases in the occlusal vertical dimension (iOVD), it is hypothesized that spindle function would adapt to a decrease in occlusal vertical dimension (dOVD) as well. Seventy-five 5-week-old female Wistar rats were divided into Control (n = 25) and Experimental (n = 50) groups ; those in the Experimental group received a 2.0-mm composite resin build-up to the maxillary molars. The Experimental group was divided into the resin-removal group (n = 25, build-up resin was removed) and the non resin-removal group (n = 25) 8 weeks later ; i. e., when the animals were 13 weeks old. Electrophysiological recordings were obtained from masseter-muscle spindle afferents in 13, 14, 15, 19, 21-week-old rats (n = 5 rats each) under general anesthesia. Masseter-muscle spindle sensitivity was significantly lower in the resin-removal group 1 week after resin-removal and for the rest of the observation period. The present results indicate that masseter-muscle spindles may not completely adapt to dOVD and may affect jaw function.抄録全体を表示PDF形式でダウンロード (2503K) -
白須 健一郎2008 年 75 巻 1 号 p. 6-12
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーThe purpose of this study was to assess the influence of residual stress produced after the bending manipulation of a straight wire on flexibility and permanent deformation of wrought-wire clasps. A three-dimensional finite element model of a straight wire (12 mm in length and 1.0 mm in diameter) was created. Elastic and plastic properties of a commercial Co-Cr straight wire measured by means of tensile test were input into the program. We simulated the bending of the clasp shoulder and clasp arm to an angle of 90° or 120° and subsequent unloading processes with spring-back phenomenon. The maximum residual tensile stress appeared at the inside of the bending angle after unloading of the bending force. Thereafter, the clasp models were deflected 0.25, 0.50 mm, and 0.75 mm at the tip to simulate the removal and insertion of a denture. The maximum tensile stress at the inside corner of the bending angle under the deflection was considerably higher than the residual stress before deflection. The stress increase by the deflection was larger at the shoulder than the arm. The load required for deflection was larger in the models with the arm of 120° angle than models with the arm of 90° angle. The results suggest that the permanent deformation of wrought-wire clasps is likely to initiate at the clasp shoulder, while the clasp flexibility is dependent on the bending angle of the clasp arm.抄録全体を表示PDF形式でダウンロード (3127K) -
横山 佳子2008 年 75 巻 1 号 p. 13-28
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーCementum is an essential tissue to maintain tooth function and should be closely correlated to tooth root development and periodontal tissue regeneration. However, detailed features of the periodontium including cementum and specific markers for cementoblasts are unknown. Moreover, the molecular mechanism of periodontal tissue development, homeostasis and regeneration remains unknown. Previous studies have usually examined cementum or periodontal ligament (PDL) tissue obtained by manual curettage, resulting in difficulties in isolating pure cementum or PDL. We employed laser capture microdissection (LCM) to isolate cementoblasts and PDL cells from undecalcified frozen sections of murine mandible and to obtain RNA of good quality for subsequent genetic analysis. Over 500 cementoblasts and PDL cells were separately laser captured under microscopy. A bioanalyzer detected peaks of 185 and 285 rRNA both in the laser-dissected cementoblasts and in PDL cells, suggesting that the RNA was of sufficient quality. The RNA samples were amplified due to their small amount and a comparative analysis of mRNA expression by GeneChip showed that about 2, 000 genes were differentially expressed between cementoblasts and PDL cells. Both cementoblast-positive and PDL cellnegative genes were serially analyzed by quantitative RT-PCR using RNA samples obtained from mandibles and femurs. Several genes were expressed at higher levels in the mandible than in the femur, suggesting that some might be cementoblast-specific markers. We established a novel experimental system with which to isolate target tissues from single cells in undecalcified frozen sections and to obtain intact RNA. These methodologies could be useful for further investigation of mineralized tissues and to explore tissue-specific factors.抄録全体を表示PDF形式でダウンロード (5799K) -
後藤 暢大2008 年 75 巻 1 号 p. 29-37
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーBMP-12, other than BMP-2, 4, and 7, is known to induce the formation of tendon/ligament-like tissues. However, the role of the protein in the process of bone or cartilage healing has not been adequately examined. The purpose of the present study was to examine if a plasmid vector encoding BMP-12 would induce tendon/ ligament formation in a rat bone defect model. A lyophilized atelocollagen pellet with 100μg of a plasmid vector encoding BMP-12 or BMP-2 was implanted in a bone defect of a rat femoral metaphysis. The samples were retrieved at 2, 4 and 8 weeks post-operation and subjected to histology and real-time PCR analysis. BMP-12 transgene indicated prominent fibrogenesis at 2 weeks. Consequently, the tissue was substituted by bone at 8 weeks. The gene expression of collagen type III was up-regulated by BMP-12 gene transfer after 2 weeks, followed by an increase of elastin and Sixl genes after 4 weeks. These genes, which are intimately related to tendon/ligament formation, decreased in expression at 8 weeks in preparation for osteogenesis afterward. On the other hand, the BMP-2 transgene quickly induced the synthesis of bone-related genes such as collagen type I and ALP. It is concluded that BMP-12 can initiate the development of tendon/ligament-like tissue in a rat bone defect at early healing stages. Maintaining such generation of tissue on bone could be useful for modifying periodontal tissue engineering.抄録全体を表示PDF形式でダウンロード (7574K) -
田村 昌平2008 年 75 巻 1 号 p. 38-48
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーThe effects of oral commensal streptococci (Streptococcus sanguinis, Streptococcus gordonii, Streptococcus mitis, and Streptococcus salivarius) on Biofilm formation by cariogenic mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) were investigated. Cell suspensions were cultured on 96-well microtiter plates coated with or without salivary components (SC), and in flow cell systems coated with SC in tryptic soy broth including 0.25% sucrose without dextrose (TSB) . The resultant biofilm formations were stained using safranin or a LIVE/DEAD® BacLightTM Viability Kit, and examined with absorbance at 492 nm or using confocal laser scanning microscopy. Mutans streptococci and S. sanguinis biofilms were formed significantly on the polystyrene surfaces in TSB. Further, in combination cultures, S. sanguinis formed a sufficient biofilm when cultured with S. mutans. However, when S. sanguinis was cultured with S. sobrinus, biofilm formation was slightly inhibited. S. gordonii also inhibited biofilm formation in the culture with S. sobrinus, but not when cultured with S. mutans. S. mitis and S. salivarius collapsed the biofllm morphology and inhibited volume development in some conditions when cultured with S. mutans or S. sobrinus. Biofilm formation by mutans streptococci was challenged and collapsed on the whole by culturing with each of the other oral streptococci. These results indicate that co-culturing of multiple species of mutans streptococci and other oral streptococci has physical effects related to previous attachment and colonization on the surface, as well as biological effects to regulate biofilm formation.抄録全体を表示PDF形式でダウンロード (6669K) -
西村 賢市2008 年 75 巻 1 号 p. 49-54
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーDecrease of the alveolar ridge after tooth extraction causes difficulties in prosthodontic treatment, especially in implant supported prostheses. Statins, which are inhibitors of cholesterol synthesis and therapeutic drugs for hypercholestemia, stimulate BMP-2 expression in osteoblasts. The purpose of the present study was to examine how local application of Simvastatin, one of the statins, to the tooth socket after tooth extraction affects alveolar bone. A mixture of lactic acid/glycolic acid copolymer (PLGA), a-tricalcium phosphate (a-TCP), calcium carbonate was prepared as a carrier for simvastatin. Ninety-six male Wistar rats, 10 weeks old, were used. After right mandibular incisor extraction, they were divided into eight groups and tooth sockets were treated differently : no treatment (control), PLGA carrier only, or PLGA containing 0.1, 0 0.5, 1.0, 2.0, and 4.0 mg simvastatin, respectively. They were sacrificed at 4 and 8 weeks. Bone mineral content (BMC) of the alveolar ridge was measured with dual-energy X-ray absorptiometry and histological analyses were performed. All groups treated with simvastatin showed higher BMC compared to the control group and PLGA carrier group at 4 and 8 weeks. Histological analyses revealed that the thickness of cortical bone of the statin group increased compared to the control group at 4 and 8 weeks ; however, newly-formed bone in the tooth socket of the statin group was less than in those of the control group and PLGA carrier group. The results of this study show that local application of simvastatin may enhance bone formation and preserve the alveolar ridge after tooth extraction.抄録全体を表示PDF形式でダウンロード (1923K) -
工藤 淳夫2008 年 75 巻 1 号 p. 55-64
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーDistraction osteogenesis has been widely used even in the craniofacial region. A long fixation time during the consolidation period, however, is a major clinical disadvantage. Hyperbaric oxygen (HBO) has been used to improve healing in ischemic wounds. We have recently started applying hyperbaric oxygen to cleft palate patients after maxillary distraction, but there is little basic evidence. We hypothesized that hyperbaric oxygen would enhance the healing of distraction osteogenesis in the cleft palate model in dogs. A bony segment including a canine was transported proximally into an artificial bone defect in the left palate. Three dogs were treated with hyperbaric oxygen for 20 days just after the distraction and three other dogs underwent only the distraction process (control group) . Blood flow of the canine pulp in the bone segment was monitored using a laser Doppler flowmeter throughout the experiment. All the dogs were sacrificed on day 100, and radiological analysis using peripheral quantitative CT and histomorphometric evaluations were performed. Blood flow in the HBO-treated group recovered to the original level about 30 days faster than in the control group (p<0.05) . Cortical bone mineral density was significantly higher at the distraction site in the HBO-treated group than in the control group (p<0.05) . The histomorphometric analysis revealed that the newly formed bone area was also larger in the HBO-treated group than in the control group (p<0.05) . These results suggest that hyperbaric oxygen treatment could be useful for early removal of the distraction device in distraction osteogenesis.抄録全体を表示PDF形式でダウンロード (9005K) -
2008 年 75 巻 1 号 p. 65-80
発行日: 2008/03/31
公開日: 2010/10/08
ジャーナル フリーPDF形式でダウンロード (2821K)
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