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Introduction: Dental plaque pH decreases to about 4 through bacterial fermentation of carbohydrates and this low pH is maintained for from several minutes to about an hour. Repeated acidification causes demineralization of the tooth surface, resulting in caries formation. The acidification also influences plaque bacteria. Severe acidification kills bacteria efficiently, while physiological acidification, the condition occurring in plaque, kills bacteria partially and may impair growth ability. We, therefore, investigated the effects of physiological acidification on representative caries-related bacteria. Methods: Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, Streptococcus oralis, Lactobacillus paracasei, and Actinomyces naeslundii were used. Effects of physiological acidification at pH 4.0 on cell viability and growth ability, as well as the growth rate of these bacteria at pH 4.0–7.0, were investigated. Results: Mutans streptococci and Lactobacillus grew at pH 4.0 but the growth of S. sanguinis and S. oralis ceased below pH 4.2 and pH 4.2–4.4, respectively. Acidification at pH 4.0 for 1 h killed 43–89%, 45% and 35–76% of S. sanguinis, S. oralis, and Actinomyces, respectively. Furthermore, assessment of bacterial growth curves revealed that the growth ability of the surviving cells of S. sanguinis, S. oralis and Actinomyces was impaired, but it was recovered within 2–5 h after the environmental pH had returned to 7.0. The acidification neither killed nor impaired the growth of mutans streptococci and Lactobacillus. Conclusions: These results indicate that physiological and transient acidification is not sufficient to kill bacteria, but it causes a temporary acid-impairment of their growth ability, which may function as an ecological determinant for microbial composition in dental plaque.

This paper presents a six-year-old patient with XXXXY syndrome, whose oral findings included a cleft soft palate, hyper- or meso-taurodontism in eight primary molars and in the mandibular permanent first molars, five congenitally missing premolars, and delayed development of the permanent tooth germs. The maxillary and mandibular primary central incisors were in a cross-bite relationship. Cephalometric findings showed a short ramus of the mandible and a short maxilla in the anterio-posterior plane. The anteroposterior jaw relationship was in harmony. The cross-bite was considered to be due to the retroinclination of the maxillary primary incisors. This case emphasises the importance of regular dental care, and monitoring of facial growth and dental development in children with XXXXY syndrome.

The bite force prior to orthodontic treatment was determined to examine whether occlusal and masticatory functions in children with cleft lip and/or palate (CL/P), but with most teeth participating in occlusion, are inferior to those in children with normal occlusion without CL/P. The subjects were 31 children (20 boys and 11 girls) with CL/P and 26 children (10 boys and 16 girls) with normal occlusion without CL/P. All the children were 4 years old. To examine occlusal function, we measured the occlusal contact area, bite pressure, and bite force using bite pressure detection film “dental prescale” (R-type) and the “Occluser” system (Fuji Photo Film Co.). The average and maximum bite pressures in children with CL/P were significantly higher than those for children with normal occlusion without CL/P. The bite pressure and bite force in children with CL/P were similar to or greater than those for children with normal occlusion without CL/P, provided that the children with CL/P had only a slightly asymmetric dental arch and that most teeth participated in occlusion. These results suggest that occlusion functions in children with CL/P are not inferior to those of children with normal occlusion without CL/P.

The purpose of the present study was to examine age-related change of the pulpal blood flow (PBF) in human primary teeth. PBF of 21 healthy upper primary central incisors in 12 children (age: 3 years 11 months–7 years 3 months) was measured by laser Doppler flowmetry (LDF). Recordings were made with and without opaque black rubber dam application. On 10 of the examined teeth, repeated measurements were made on different occasions: twice on 4 teeth (3 subjects) and 3 times on 6 teeth (3 subjects). The results obtained were as follows: PBF with dam application was significantly decreased with increasing age of the subjects ( P

Matrix metalloproteinases (MMPs) have been expressed during root development and periodontal tissue formation, whereas it is not known if these MMP molecules are enzymatically active to degrade the extracellular matrices (ECMs). The present study was designed to investigate the gelatinolytic and collagenolytic activity in rat molar root and incisor development. Three-week old rat mandibles were frozen and cut without fixation or decalcification and processed for in situ zymography using substrates gelatin and collagen. The enzymatic activity was assessed according to the intensity of fluorescence due to the lysis of the substrates. Odontoblasts, predentin, cementum, bone and the enamel matrix showed the high activity. The present study demonstrated MMP activity in calcified tissues using in situ zymography for the first time and the possible involvement of the MMP activity in molar root and incisor development and periodontal tissue formation.

The EFA6 family is a member of guanine nucleotide exchange factors (GEFs) that can activate ARF6 specifically in vitro. In this study, we determined the complete primary sequence of mouse EFA6D encoding a protein of 1004 amino acids with a calculated molecular weight of 111,207 Da. In ARF pull-down assay, EFA6D showed a preferential GEF activity toward ARF6. RT-PCR analysis revealed the widespread tissue distribution of EFA6D and the high expression of EFA6A, C and D in the brain. In situ hybridization analysis demonstrated a distinct spatiotemporal expression pattern of EFA6D from those of EFA6A and C in mouse brain. Furthermore, immunoblot analysis revealed that EFA6D was highly concentrated in the postsynaptic density fraction. These findings suggest differential spatiotemporal regulation of ARF6 by three members of the EFA6 family in the brain.

Since 1972, we have been conducting an annual clinical dental examination for young children at 13 nursery schools in the north district in Sendai, Japan. In the present study, we have included the results of examinations conducted in 1997 and 2002, and analyzed the time trends in caries experience of the primary dentition over a 30-year period from 1972 to 2002. The caries experience in the primary dentition markedly decreased in 1977 and remained stable for about 15 years, but in 1997, it markedly decreased again and continued to decrease in a linear fashion until 2002. The time trends in caries experience in the primary dentition in each age group were further analyzed by ascertaining caries experience in each tooth type. The results showed that, in 2 to 4-year-old, the decrease of caries experience for the primary maxillary incisors, canines and first molars seemed to stop decreasing in 2002, but for the 5-year-old, the caries experience for the maxillary incisors and canines and the maxillary and mandibular first and second molars markedly decreased from 1997 to 2002.

In this study, pulpal blood flow (PBF) of human primary teeth was measured using laser Doppler flowmeter (LDF) and efficacy of opaque rubber dam application was examined. Twenty-two healthy and 3 non-vital upper primary central incisors in 13 children (age: 3 years 11 months–7 years 3 months) were examined. Recordings were made with and without opaque rubber dam application. Electrocardiogram (ECG) of the subjects was simultaneously recorded. Results obtained were as follows: 1) With dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth, whereas no pulsatile signals were recognized in non-vital teeth. 2) Without dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth and non-vital teeth. 3) The amplitude of blood flow signal was significantly reduced by the opaque dam application. Results indicated that PBF measurement using LDF with dam application in human primary central incisors was applicable for pulp vitality assessment.

Tooth eruption involves extensive degradation and reorganization of extracellular matrix (ECM) components. It is not known how ECM-degrading enzymes are coordinated with each other or how they are regulated in the event. The present study was designed to investigate mRNA expression of inhibitors of metalloproteinases (TIMPs) in comparison with matrix metalloproteinases (MMPs) as well as ECM molecules during rat first molar eruption using in situ hybridization. We also examined how TIMPs are involved in the process of tooth eruption, root formation, cementogenesis and alveolar bone remodelling. Expressions of type-I collagen, osteocalcin, MMPs 2 and 8, and TIMPs 1, 2 and 3 were shown in osteoblasts, osteocytes, cementoblasts, cementocytes and periodontal ligament fibroblasts, and the concomitant high expressions of the ECM molecules, MMPs and TIMPs in alveolar bone, cementum and periodontal ligaments were identified in the middle of first molar eruption. The remodelling of ECM in these periodontal tissues might be regulated through balance among the production of ECM molecules, the degradation of ECM by MMPs and the inhibition of MMPs by TIMPs during tooth eruption.

Xylitol inhibits the glycolysis and growth of Streptococcus mutans. We studied the inhibitory effect of xylitol on the acid production of S. mutans at several pH levels under the strictly anaerobic conditions found in the deep layer of dental plaque. Xylitol inhibited the rate of acid production from glucose and changed the profile of acidic end products to formate-acetate dominance, with a decrease in the intracellular level of fructose 1,6-bisphosphate and an intracellular accumulation of xylitol 5-phosphate (X5P). These results were notable at pH 5.5-7.0, but were not evident at pH 5.0. Since the activity of phosphoenolpyruvate phosphotransferase for xylitol was greater at higher pH, it is suggested that xylitol could be incorporated more efficiently at higher pH and that the resultant accumulation of X5P could inhibit the glycolysis of S. mutans more effectively.

– The purpose of this study was to examine the age-related changes in human pulpal blood flow (PBF). Recordings were taken from 22 clinically healthy upper central incisors in 22 healthy participants (age: 8–75 years). A Moor blood flow monitor (type MBF3D) was used to measure PBF; and subjects' electrocardiogram (ECG), mean blood pressure (BP) and heart rate (HR) were also recorded. The resting PBF was significantly decreased with the increased age of the participants (Pearson's correlation coefficient, P

We investigated the effects of chronic administration of zonisamide, an antiepileptic agent, on bone metabolism in growing rats. Administration of zonisamide at a dose of 80 mg/kg per day, s.c. for 5 weeks significantly decreased bone mineral density (BMD) at the tibial metaphysis and the diaphysis. The percent rate of decrease in BMD at the tibial metaphysis and the tibial diaphysis was 9.2% and 5.0%, respectively. There was no significant difference between these groups in the growth of the rats. Treatment with zonisamide at a dose of 80 mg/kg increased serum pyridinoline level, a marker of bone resorption, while it does not affect the serum intact osteocalcin level, a marker of bone formation. Combined administration of alfacalcidol, an active vitamin D(3) metabolite, at a dose of 0.1 microg/kg per day with zonisamide prevented a decrease in BMD and showed an increase of serum pyridinoline levels. These results suggest that zonisamide may cause bone loss by accelerating bone resorption rather than inhibiting bone formation. Moreover, the bone loss induced by zonisamide could be prevented by combining zonisamide with alfacalcidol.

Benign mixed and mesenchymal odontogenic tumors (ameloblastic fibroma, ameloblastic fibrodentinoma, ameloblastic fibro-odontomas, odontogenic fibroma and odontogenic myxoma) were immunohistochemically examined using antibodies against amelogenin, cytokeratin 19, bcl-2, hepatocyte growth factor (HGF), c-Met, transforming growth factor-β (TGF-β), TGF-β receptors and Ki-67 to know cytodifferentiation, epithelial-mesenchymal interaction and proliferative activity. Expression of amelogenin was detected in odontogenic epithelial cells and enamel matrices in ameloblastic fibro-odontomas, and cytokeratin 19 was expressed in odontogenic epithelial cells, indicating odontogenic epithelial properties. Expressions of bcl- 2, HGF, TGF-β, TβR I and TβR II were detected in odontogenic epithelial and mesenchymal cells in mixed and mesenchymal odontogenic tumors, while expression of c-Met was detected in odontogenic epithelial cells. Odontogenic epithelial and mesenchymal cells sporadically showed positive reactions for Ki-67 in mixed and mesenchymal odontogenic tumors, and no apparent differences were obtained among these tumors or between the components. Conclusion: Immunohistochemical localization of HGF, TGF-β and their receptors suggests that these growth factor signaling are effective in the epithelial component in paracrine and autocrine manner in mixed and mesenchymal odontogenic tumors. These results of growth factor signaling suggest that certain epithelial-mesenchymal interactions are related to neoplastic cell growth in these tumors.

Alendronate (A), a typical aminobisphosphonate (aminoBP), has a strong bone-resorption-inhibitory activity (BRIA). However, like other aminoBPs it has inflammatory side effects. In contrast, the BRIA of clodronate (C), a non-aminoBP, is much weaker, and in animal experiments it suppresses aminoBP-induced inflammatory reactions. In the present study, we examined the effects of weekly administrations of A (1.6 micro mol/kg) + C (160 micro mol/kg) on the tibias in young mice and compared them to those induced by A or C alone. Radiophotography showed that A increased bone density at a selective site in the tibia. Indeed, one week after the final injection of A (given alone), clear sclerotic lines (tentatively called BP-lines) were visible at sites corresponding to the location of the growth plate at the time of the each injection. C also produced BP-lines, although they were weaker than those produced by A. Combined administration of A and C produced similar BP-lines as seen in mice given A alone. These results together with other physicochemical effects of A on the tibia suggest that (1) each injection of A and C inhibits bone resorption selectively and transiently at the tibial growth plate in young mice, although minor effects on other sites cannot be excluded, and (2) the combination of A and C keeps still a strong BRIA. Our findings may suggest a strategy for the prevention or reduction of some inflammatory side effects of A or other aminoBPs.

A pH-sensitive fluorescent dye, 2', 7'-bis-(2-carboxyethyl)-5 and 6-carboxyfluorescein (BCECF), was used to determine intracellular pH (pH(in)). The efflux of BCECF loaded into oral streptococcal cells was determined after incubation of the cells at 35 degrees C for 20 min in the presence and absence of glucose. In the absence of glucose, the fluorescence of intracellular BCECF in Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius and Streptococcus sobrinus decreased only very slightly, indicating that the dye could be useful for pH(in) determination. In the presence of glucose, however, the fluorescence decreased by 57%. Thus, the pH(in) of S. mutans cells was measured by the BCECF method in the absence of glucose at various acidic pH levels by adding lactic, acetic and hydrochloric acids to the cell suspensions. The pH(in) was almost equal to the extracellular pH (pH(out)) for pH(out) values of between 8 and 5, indicating that protons permeated easily across the S. mutans cell membrane. For pH(out) between 5 and 4, pH(in) was constant at around 5, suggesting that the cell membrane was impermeable to protons, or that a cytoplasmic buffering system functioned. pH(in) decreased at pH(out) values of < 4. The constant pH(in) at acidic pH(out) levels could protect intracellular components, such as proteins, against acidification by sugar fermentation.

Fourteen patients with oral chronic graft-versus-host disease (GVHD) who received allogenic bone marrow transplantation were clinically and histopathologically studied. Most patients had lichenoid lesions on the oral mucosa and xerostomia. Two patients displayed multiple superficial mucoceles of the buccal mucosa as vesicular lesions. These clinical features resembled those of autoimmune diseases, such as lichen planus and Sjogren's syndrome. Histopathologically, all cases showed oral mucosal and minor salivary gland involvement characteristic of chronic GVHD, irrespective of the presence or absence of systemic lesions. The oral mucosa showed subepithelial lymphocytic infiltration with epithelial recessive changes, and the minor salivary glands displayed inflammatory changes or fibrosis with destructive alteration of epithelial cells. Immunohistochemically, CD3-positive cells were more numerous than CD79α-positive cells in the oral mucosa, while CD3- and CD79α-positive cells were equally observed in the minor salivary glands. CD4- and CD8-positive cells were detected equally in both the oral mucosa and the minor salivary glands. CD1a- and CD68-positive cells were scattered throughout the oral mucosa and the minor salivary glands. Cellular and humoral immune systems may differ between the oral mucosa and salivary glands in patients with chronic GVHD. CD1a- and CD68-positive cells may play a role in antigen presentation in oral lesions involved in chronic GVHD.

Method and Results: Calcifying odontogenic cysts (COCs) were examined histopathologically and immunohistochemically to characterize the histological and cytological properties of these lesions. Histopathologically, COCs showed thin or thick lining epithelium with ghost cells. COCs were classified according to proliferative type or nonproliferative type lining epithelium, the presence or absence of ameloblastomatous appearance, and the presence or absence of odontoma in the cyst walls. Immunohistochemically, amelogenin protein was expressed chiefly in ghost cells, whereas cytokeratin 19 (CK19) and bcl-2 proteins were expressed chiefly in lining epithelial cells. The proportion of cases positive for bcl-2 protein was slightly higher in COCs with odontoma than in those without odontoma. Lining epithelial cells sporadically showed positive reactions for Ki-67 antigen. Mean Ki-67 labeling index was slightly greater in COCs with proliferative type lining epithelium, COCs with ameloblastomatous appearance of the cyst walls, and COCs with odontoma of the cyst walls than in COCs without these histological features. Our results suggest that ghost cells or lining epithelial cells show ameloblastic cytodifferentiation or odontogenic epithelial characteristics, that bcl-2 protein is associated with survival of lining epithelial cells in COCs, and that high proliferation potential is associated with ameloblastomatous proliferation or combined odontoma. COCs exhibited various histological features with several transitional forms, and immunohistochemical examinations revealed little or no difference in cytodifferentiation and cellular activity among COCs. Conclusion: We conclude that COCs with various histological features have neoplastic potential and may not be separate entities within the same histological spectrum.

Studies were carried out to determine the effects and mechanism of action of phenytoin on the bone metabolism in male rats. Administration of phenytoin, 20 mg/kg/ day for 5 weeks, did not affect the growth curve. Biochemical data indicated that the serum osteocalcin, a marker of bone formation, was decreased significantly but there were no significant differences in the levels of serum calcium, pyridinoline, 25-hydroxyvitamin D3 (25OHD) and parathyroid hormone (PTH) in the phenytoin-treated group compared with the vehicle-treated group. The values of bone mineral density (BMD) were decreased in all regions of bones tested (mandibular head, tibial metaphysis, tibial diaphysis, femoral metaphysis, and femoral diaphysis) in the phenytoin-treated group. In histomorphometric analysis, phenytoin decreased trabecular bone volume and trabecular thickness, and increased osteoclast numbers per area of bone surface in the secondary trabecular bone of the tibia. Additionally, there was no significant difference in osteoid thickness. Combined administration of either alfacalcidol or calcitriol with phenytoin for 5 weeks prevented the reduction of BMD induced by phenytoin. From these findings, it is unlikely that toxic effects on the growth curve caused the decreased BMD induced by phenytoin. It is also evident that repeated administration of phenytoin may cause osteopenia which may be due to bone loss by inhibiting bone formation and/or by accelerating bone resorption rather than osteoid accumulation. The bone loss is not rachitic because of the lack of increase in osteoid thickness. Moreover, combined administration of alfacalcidol or calcitriol with phenytoin showed a preventative effect against bone loss. The bone loss induced by phenytoin in this study may be a convenient model for further research into the problem of drug-induced osteopenia.

Beta-galactosyllactose is a trisaccharide containing the beta-galactosidic linkage at the nonreducing end. The purpose of this study was to determine whether certain oral streptococci could utilize four kinds of beta-galactosyllactoses. Three of four beta-galactosyllactoses were unable to support growth of the oral streptococci and to be a substrate for producing acid from the cell suspensions and dental plaque. 4'-beta-Galactosyllactose supported growth of Streptococcus sanguis ATCC 35105, ATCC 49298, Streptococcus mitis ATCC 15914, Streptococcus oralis ATCC 35037, ATCC 10557 and Streptococcus milleri 10707 and produced acid from dental plaque. Although beta-galactosidase activities were observed in all the strains, 4'-beta-galactosyllactose could not be used as a carbon source for the growth of mutans streptococci. Enzymes metabolizing 4'-beta-galactosyllactose were induced when S. oralis ATCC 10557 was cultured in medium containing galactose. These results suggested that 4'-beta-galactosyllactose could be as cariogenic as lactose if it is consumed frequently and retained for a long period in the mouth.

Lipopolysaccharide (LPS) produced by Gram-negative bacteria is an important cause of inflammation. Aminobisphosphonates are potent inhibitors of bone resorption but have inflammatory side-effects. Here, the effects of LPS from Prevotella intermedia (a prevalent Gram-negative bacterium both in periodontitis and endodontal infections) and alendronate (an aminobisphosphonate) on the activity of the histamine-forming enzyme, histidine decarboxylase (HDC), were examined in mouse mandible. Intravenous injection of P. intermedia LPS increased HDC activity in the mandible, maximal activity being induced within 3-6 h of the injection. The elevation of HDC activity was dependent on the dose of LPS, 10 microg/kg (0.25 microg/mouse) producing a significant elevation in enzyme activity. Intraperitoneal injection of alendronate (40 micromol/kg) also produced an increase in HDC activity. Moreover, the elevation of HDC activity induced by P. intermedia LPS was markedly augmented in mice given alendronate 3 days before the LPS injection. These results (i) suggest that P. intermedia LPS may stimulate the synthesis of histamine in the mandible and that the newly formed histamine may make at least some contribution to the development of inflammation (apical periodontitis and/or osteomyelitis); (ii) should encourage the clinical testing of antihistaminergic agents against inflammation; and (iii) confirm that care needs to be taken when administering aminobisphosphonates to patients.

ラット臼歯有細胞セメント質における細胞外基質形成過程を明らかにするため, 本研究では生後3週, 4週および6週齢ラットを用いin situ hybridization (ISH) による検討を行った。I型コラーゲンの遺伝子発現は3週齢ラットのセメント芽細胞と歯根膜細胞に広く認められ, 4週以降これら陽性のシグナルは低下した。一方, 骨シアロタンパク質 (BSP) およびオステオカルシン (OC) の遺伝子発現は3週齢ラットのセメント芽細胞に強く, また近傍の歯根膜細胞に弱く認められた。これら陽性のシグナルは, 4週齢で著しく低下し6週齢ではほとんど認められなかった。以上の結果より有細胞セメント質におけるI型コラーゲン, BSPおよびOCの遺伝子発現は分化初期のセメント芽細胞に強く発現することが示唆された。

The present study was designed to examine the distribution of interglobular dentine in human tooth roots. The material comprised 17 teeth, of which 3 were premolars extracted for orthodontic reasons from children 10–12 years of age and the other teeth (4 incisors, 3 canines and 7 molars) were extracted for periodontitis from individuals aged 32–63 years. All teeth were free of caries and cervical dentine defects. Ground sections of the teeth cut longitudinally were stained with basic fuchsin and observed by fluorescence and confocal microscopy as well as transmitted light microscopy. Basic fuchsin stained the dentinal tubules, interglobular dentine and the granular layer of Tomes. These structures appeared intense blue to faint violet with transmitted light microscopy, whereas their staining displayed intense fluorescence with fluorescence microscopy. Therefore, the interglobular dentine could be detected more sensitively with fluorescence and confocal microscopy than with transmitted light microscopy. Typical interglobular dentine was present in coronal dentine in most of the teeth. In the radicular dentin, position and size of the interglobular dentine was different among the teeth examined. Most of the teeth had the interglobular dentine in the cervical part of the roots (type A). Two premolars displayed the interglobular dentine in the coronal half of the root (type B). The types A and B contained large interglobular areas. A small amount of interglobular dentine was restricted to the apical half of the roots of two canines and one molar (type C). In contrast to types A and B which were seen at both labial or buccal and lingual sides of roots, the interglobular dentine of type C was seen only at one side, labial or lingual. Some of the tooth roots did not show any interglobular dentine (type D). Most of the incisors, canines and premolar were types A, B, and C, respectively, and the molars were mixed types A, C, and D. These results suggest that the factors affecting dentinogenesis during root formation are unique for each tooth.

成熟ラット臼歯において, 有細胞セメント質が明セメント質 (LC) と暗セメント質 (DC) に分類されることが報告されている. これらの有細胞セメント質の形成過程を明らかにするため, 本研究では生後4, 6, 8週齢ラットを用いて免疫組織化学的検討を行った.LCは歯根遠心側にDCは近心側に出現し, 両者は加齢により厚さが増大した. LCに対面する歯槽骨表面は吸収面であり, DCに対面する骨表面は形成面であった. 各週齢のLCは類セメント質と同様に抗オステオカルシン抗体に陰性, DCは陽性であった. LC表面の細胞はDC表面の細胞と同様にオステオカルシンを発現していた.アルシアンブルー染色および免疫染色により, LCではコンドロイチン硫酸が多く, DCでは少なかった.これらのLCの免疫組織化学的特徴は類セメント質の特徴に類似し, 歯根遠心側へのLCの出現には歯に加わるメカニカルストレスが関与することが示唆された.

ラット三叉神経節から舌機械刺激に応答するニューロンを記録し, その反応特性を調べた。舌応答ニューロンは三叉神経節尾外側の下顎神経支配領域の尾側から記録された。舌応答ニューロン領域には, 顎・顔面皮膚, 口唇および下顎切歯・臼歯に反応するニューロンも混在していた。舌応答ニューロンの約90%は遅順応性, 残り10%は速順応性であった。舌応答ニューロンの受容野は非常に小さく (1mmmm2以下), 舌全体に分布していたが, 舌尖部に特に高密度に集中し, 次に舌縁部にも多く観察された。刺激強度と反応の大きさの関係を表すベキ関数法則を遅順応性ニューロンに適用すると, ベキ指数は0.77±0.38であった。伝導速度は遅順応性で2m/sec以下と12～16m/secに, 速順応性で12～14m/secに多く観察された。したがって, 舌では舌尖および舌縁部の感覚識別能が最も高く, この部分からの舌感覚情報が咀嚼および嚥下等の口腔機能に最も深く関与しているものと推察される。

The development of interglobular dentine in the first upper and lower molars of Wistar rats aged 3, 7, 14, 21, 42 days was examined histochemically using a lectin, succinyl wheat germ agglutinin (sWGA), which is specific for N-acetyl-D-glucosamine. sWGA stained the interglobular dentine, predentin and Golgi area of odontoblasts. Interglobular dentine was not formed in the first molars of 3-day rats, but appeared in those of 7-day rats near the enamel-free area. In 14-day rats, interglobular dentine was present in most areas of the coronal dentine except the cervical area. At the interface between dentine and predentin, numerous sWGA-negative calcospherites were seen, suggesting that the interglobular dentine is formed actively there. In 21-day rats, the interlobular dentine was more numerous than in 14-day rats. Interglobular dentine was present in the cervical root dentine as well as in the coronal dentine, including the cervical area. The distribution of interglobular dentine in 42-day rats was similar to that in 21-day rats, but fluorescence of sWGA binding was less intense in the former. Because the development of interglobular dentine appeared to be time and position specific its relation to the stages of ameloblasts was analysed. Thin enamel matrix was formed at cusps in molars of 3-day rats and thickness of enamel matrix increased in 7-day rats. In these teeth, the ameloblasts were at the differentiating or secretory stage. The Golgi area and Tomes' processes of the secretory ameloblasts, the cells of intermediate layer and the enamel matrix were weakly positive with sWGA. The epithelial cells at the enamel-free area were also stained with sWGA. In 14-day rats, most of the ameloblasts in the first maxillary molars were at the maturative stage except in the cervical area, where the ameloblasts were at the transitional stage. sWGA stained the distal border and the Golgi area of the maturative ameloblasts as well as the cells of the papillary layer. The distal border of the maturative ameloblasts appeared either thick or thin, suggesting a ruffle-end and smooth-end of the cells. Ameloblasts were absent in the first molars of 21-day rats and the cervical part of the enamel was covered with the stratified epithelium like that of 42-day rats. The present study has demonstrated that interglobular dentine contains sWGA-binding glycoconjugates and the formation of the interglobular dentine is largely associated with the enamel maturation. These results suggest that matrix-to-cell interaction is important for the development of interglobular dentine.

The effects of phenytoin and its major metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), on bone resorption of neonatal mouse calvaria were examined in vitro. Both phenytoin and HPPH induced significant bone resorption as compared to the controls after 72 h in culture. This effect may be the cause of phenytoin-induced bone loss in vivo.

Human cationic antibacterial protein CAP18/LL-37 exhibits bactericidal and various immunobiological activities. The constitutive expression of CAP18/LL-37 in oral epithelial cells was demonstrated, and that CAP18/LL-37 activated human gingival fibroblasts to enhance production of hepatocyte growth factor, which has been shown to exert multiple biological activities. These findings might be related to restoration and regeneration of periodontal tissues.

The purpose of this study was to examine the relation between the root resorption and the pulpal blood flow (PBF) in human primary teeth using laser Doppler flowmeter (LDF). Recordings were made on 15 clinically healthy upper primary central incisors in nine healthy participants (age: 3 years 11 months-7 years 3 months). The state of roots of the teeth examined were confirmed by radiographs. The mean PBF signals tended to decrease with the progress of the root resorption. Results indicated that PBF could indicate the status of the root resorption in the human primary teeth.

This study evaluated acid production from cooked starch by Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus mitis, and the effects of α-amylase inhibitors (maltotriitol and acarbose) and xylitol on acid production. Streptococcal cell suspensions were anaerobically incubated with various carbohydrates that included cooked potato starch in the presence or absence of α-amylase. Subsequently, the fall in pH and the acid production rate at pH 7.0 were measured. In addition, the effects of adding α-amylase inhibitors and xylitol to the reaction mixture were evaluated. In the absence of α-amylase, both the fall in pH and the acid production rate from cooked starch were small. On the other hand, in the presence of α-amylase, the pH fell to 3.9–4.4 and the acid production rate was 0.61–0.92 μmol per optical density unit per min. These values were comparable to those for maltose. When using cooked starch, the fall in pH by S. sanguinis and S. mitis was similar to that by S. mutans and S. sobrinus. For all streptococci, α-amylase inhibitors caused a decrease in acid production from cooked starch, although xylitol only decreased acid production by S. mutans and S. sobrinus. These results suggest that cooked starch is potentially acidogenic in the presence of α-amylase, which occurs in the oral cavity. In terms of the acidogenic potential of cooked starch, S. sanguinis and S. mitis were comparable to S. mutans and S. sobrinus. α-Amylase inhibitors and xylitol might moderate this activity.

The purpose of this case report is to describe an unusual presentation of multiple lesions of intracoronal resorption in the permanent teeth in a healthy boy. Longitudinal radiographs demonstrated that all 3 lesions were acquired after the crowns were completely formed. Unlike previous reports in which intracoronal radiolucencies have been found in unerupted teeth or in newly erupting teeth, one lesion in this case developed in a fully erupted tooth, which was differentiated from internal resorption and invasive cervical resorption of the root. All were considered idiopathic external resorption, but they demonstrated diversities in size, appearance, and involvement of pulp and the rate of progression. Conservative treatment was performed. All remained asymptomatic, showing normal root development. This case report indicates that intracoronal resorption is a condition demonstrating a diversity of clinical features.

Summary. We present a case of a 5-year-old boy with premature exfoliation of primary teeth. All eight primary incisors had exfoliated by the age of 3 years, and three canines and one primary first molar were subsequently lost when he was 4 years old. None of the exfoliated teeth exhibited caries. The boy also showed characteristic facial changes, tapering of the fingers, and mental and motor retardation. Based on these findings, he was diagnosed as having Coffin–Lowry syndrome. Premature exfoliation of primary teeth in Coffin–Lowry syndrome has been described in a few reports. This manifestation of the disease would be helpful for diagnosis at an early stage as those previous reports suggested.

Aims: To detect quantitatively the total bacteria and Streptococcus mutans in dental plaque by real-time PCR with prbac, Sm and GTF-B primers, and to compare their presence with the prevalence of dental caries in Japanese preschool children. Methods and Results: Human dental plaque samples were collected from the labial surfaces of the upper primary central incisors of 107 children. The dental status was recorded as dft by WHO caries diagnostic criteria. Positive dt and dft scores by the Sm or GTF-B primer were significantly higher than negative scores (P

A disintegrin and metalloprotease with thrombospondin type 1 motifs (ADAMTS) is a family of extracellular proteases and implicated in cleaving proteoglycans, such as aggrecan, versican and brevican. No information is available about expression or localization of these ADAMTSs in teeth. Versican is a large chondroitin sulfate proteoglycan that is present in a variety of connective tissue including dental pulp, dentin, cementum and periodontal ligaments. The present study was designed to investigate expression of ADAMTSs and versican during rat tooth eruption. Rat maxillary first molars in weeks 1, 2, 3, 4 and 6 were examined. The mRNA expression of ADAMTS1, ADAMTS4, ADAMTS5 and versican was localized using in situ hybridization. ADAMTS1, ADAMTS4, ADAMTS5 and versican were expressed in dental pulp cells, odontoblasts, cementoblasts, cementocytes, periodontal ligament cells, osteoblasts and osteocytes. The temporal and spatial expression pattern in these cellular phenotypes was comparable among ADAMTSs and versican. The present study suggests that dental pulp cells, odontoblasts, cementoblasts, cementocytes, periodontal ligament cells, osteoblasts and osteocytes may be involved in both production and degradation of versican with secreting ADAMTS1, ADAMTS4 and ADAMTS5.