The aim of the present study was to investigate the relationship between developmental changes in sagittal occlusion and the presence of caries on the occlusal surface of the lower first permanent molars. Dental casts were taken from 60 children at 2-monthly dental examinations after the emergence of the lower first molars through to when they reached 22 years of age. Data on the state of the occlusal surfaces of 120 lower first permanent molars were collected from these examinations and each occlusal surface classified into one of the following two categories: (1) sound, or (2) caries (filled). Sagittal occlusion of the first permanent molars was classified as Angle Class I, II, or III at each developmental stage. The data were analyzed to assess the relationship between changes in the occlusal characteristics and the presence of caries (fillings) in the lower first permanent molars. Of a total of 120 lower first permanent molars, 36 (30.0%) were filled by the end of the study period. Occlusal caries attacks occurred most commonly between 24 and 72 months after emergence of first permanent molars. New occlusal caries continued to occur thereafter, however, even though the teeth had already erupted for as long as 14 and 16 years. A Class II occlusal relationships in the lower permanent molars throughout the study period showed a significantly stronger correlation with caries than when it changed from Class II to Class I. With a Class II occlusal relationship, the percentage of teeth with fillings showed a continual increase, even though those teeth had already been erupted for between 10 and 16 years by the end of the study. These results suggest that occlusal sealing is still indicated for 3 or more years after eruption when the lower first permanent molars occlude in a Class II relationship as their risk for caries remains relatively high.

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The aim of this study is to investigate infant feeding patterns and to analyze the influence of breast-feeding methods on the prevalence of non-nutritive sucking habits in a sample of Japanese infants. A random sample of 353 mothers of infants of 18 months of age was interviewed at a public health facility in “K” city. The prevalence and duration of infant feeding patterns categorized as breast-feeding, partial breast-feeding, and bottle-feeding, were determined. The outcome investigated was the prevalence of non-nutritive sucking habits (pacifier use and finger sucking). The data were analyzed using the Chisquare and Fisher's exact tests with Bonferroni correction for multiple comparisons to assess possible association between feeding method and non-nutritive sucking behavior. The infants were categorized into the following groups depending on feeding method: breast-feeding (27.2%), partial breast-feeding (32.0%), or bottle-feeding (40.8%). Among all infants, 13.9% used a pacifier, 18.4% sucked their fingers, and 0.3% had both habits at 18 months of age. Breast-feeding was negatively correlated with pacifier use and finger sucking. In contrast, bottle-feeding was strongly associated with pacifier use and finger sucking. These results suggest that breast-feeding provides benefits to infants, and that non-nutritive sucking habits may be avoided by promoting correct breast-feeding practices.

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The purpose of this study was to clarify the effect of aging on the dentition by quantifying the dimensions of the dental arches in elderly persons aged over 80 years with 20 or more remaining teeth (8020 achievers). The study included twenty 8020 achievers (10 males and 10 females, with an average age of 82.3 years and an average of 28.3 present teeth). Their dental casts were digitized with a 3-dimensional (3-D) laser scanner, reconstructed into 3-D images, and measured with IMAGEWARE. The anterior and posterior widths of the upper and lower coronal arches and their anterior and posterior lengths together with the anterior and posterior widths of the maxillary and mandibular basal arches and their anterior and posterior lengths were measured. An unpaired t-test was performed using statistical analysis software. Dental models of 31 people with normal occlusion (16 males and 15 females, with an average age of 23.3 years) were measured with digital calipers and compared with the measurements obtained from the 8020 achievers. Several common items with significant differences were observed in the mandibular measurements. Each comparison indicated a tendency toward a decrease in size in the 8020 group: Coronal Arch P-length (p<0.05 in Male group, p<0.01 in Female group), Basal Arch A-width (p<0.05 in Male group, p<0.001 in Female group), Basal Arch A-length (p<0.001 in both group), and Basal Arch P-length (p<0.001 in both group). From these results, 3-D dental model analysis in twenty 8020 achievers revealed narrowing of the mandibular intercanine width and shortening of the mandibular anterior and posterior lengths.

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Porphyromonas gingivalis, a pathogen involved in the development of chronic periodontitis, has a number of major virulence factors, among which are its surface cysteine protease gingipains. The purpose of this study was to investigate the feasibility of inducing protective antibodies against P. gingivalis by means of immunization with recombinant Lactococcus lactis expressing the 44-kDa gingipain adhesion/hemagglutinin domain (Hgp44). Part of the Hgp44 sequence encoding the first 314 amino acid residues, residues 188-251, and residues 354-393 was amplified and inserted into shuttle plasmid pSGANC332, with the resulting chimeric plasmids designated as pISTY210, pCOL, and pSHGRP44A, respectively. After confirming the clone sequences, expression of recombinant proteins was investigated by immunoblot. The results revealed that while pISTY210 and pCOL both expressed the Hgp44 antigen on the surface of L. lactis, the level of expression was quite low. To enhance expression of the protein on the surface of the cells, cysteine residues were changed to serine residues by site-directed mutagenesis. Replacement of 3 out of 5 cysteine residues (pISTY213) significantly increased expression of the recombinant protein on the surface of the bacteria. Interestingly, replacement of the 4th cysteine residue (pISTY215) reduced antigenicity of the recombinant protein. These results indicate that expression of Hgp44 on the surface of L. lactis cells requires the replacement of several key cysteine residues, and that L. lactis expressing this antigen could be a promising candidate for immunization against P. gingivalis-induced periodontitis.

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We report a case involving a 12-year follow-up after treatment for chronic periodontitis with furcation involvement. A 54-year-old woman presented with the chief complaint of hypersensitivity. Clinical examination at the first visit revealed 15% of sites with a probing depth ≥4 mm and 35% of sites with bleeding on probing. Initial periodontal therapy was implemented based on a clinical diagnosis of severe chronic periodontitis. Surgical periodontal therapy was subsequently performed at selected sites. For #44, regenerative periodontal therapy using enamel matrix derivative (Emdogain^®) was selected. For #16, which exhibited a 2- to 3-wall vertical bony defect and class III (mesio-distal) furcation involvement, bone graft was scheduled. Other sites with residual periodontal pockets were treated by open flap debridement. For #37, with a gutter-shaped root, odontoplasty was performed. After reevaluation, the patient was placed on supportive periodontal therapy (SPT). During 12 years of SPT, the periodontal condition remained uneventful in most of the teeth. However, bone resorption was observed in the distal aspect of #37, making the prognosis poor. This indicates the need to continuously monitor risk factors, including inflammation and traumatic occlusion, during SPT. Although some problems still remain, severe periodontitis with furcation involvement was successfully maintained longitudinally with an adequate level of patient compliance and careful SPT.

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Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier.

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The Frequency with which impacted supernumerary teeth are encountered in a clinical setting is relatively high, with the majority of such cases occurrig in the median maxillary region, and very few in the molar region. In the molar region, mandibular distomolars (fourth molars) are very rare. Although a small number of case reports have described impacted supernumerary distomolars, very few have compared third molars and distomolars. Herein, the authors report two cases involving mandibular distomolars and one case a maxillary distomolar. In each of these cases, the third molar and distomolar were extracted and a macroscopic morphological analysis conducted. The results were then compared with those of the latest available literature.

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The Tokyo Dental College Oral Cancer Center was established on April 1st, 2006 at our Ichikawa General Hospital for the purpose of providing multimodal treatment for oral cancer. This report summarizes the Center's activities over the last 5 years. The total number of oral cancer patients treated was 360 (April 2006 to March 2011), with 205 primary cases. We investigated the following treatment-related items: 1) site, 2) age, 3) sex, 4) pathological examination, 5) staging, 6) systemic disorder, 7) double cancer, 8) treatment, and 9) prognosis. Out of 205 patients, 60% were men and 40% were women. Men in their 60s and women in their 80s were seen the most. The most common site was the tongue, at 42%, followed by the mandibular gingiva, maxillary gingiva, oral floor, and buccal mucosa. Squamous cell carcinomas were seen most frequently, at 94% (15% were stage I, 33% stage II, 15% stage III, and 34% stage IV). The most common treatment method was surgical treatment, at 83%. The 5-year survival rate at all stages was 85.4%. At the Oral Cancer Center, oral surgeons take the initiative in establishing treatment in cooperation with other departments and branches. Since the establishment of the Ambulatory Center for Maxillary Prosthetics in October 2011, 26 patients have undergone treatment. Related departments and branches work in teams, enabling comprehensive treatment, from the preoperative state to postoperative functional recovery. We wish to use these strengths to improve oral cancer treatment in Japan and will continue to work toward providing the best possible care for our patients.

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Angiotensin II (Ang II) plays a major role in the maintenance of extracellular fluid volume and blood pressure. In addition to its well-established role in circulatory homeostasis, it has been implicated in the process of bone formation. Osteoblasts play a major role in bone formation, employing intracellular Ca²⁺ as a second messenger to modulate hormonal responses and as a cofactor for mineralization. Voltage-dependent Ca²⁺ channels (VDCCs) mediate the influx of Ca²⁺ in response to membrane depolarization. The purpose of this study was to investigate the effects of Ang II on VDCC currents in osteoblasts using a patch-clamp recording method. To our knowledge, the data presented here demonstrate for the first time that Ang II facilitates VDCCs in osteoblasts.

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