Cell death occurs in physiological conditions and as a result of injury or disease. Programmed cell death has an important role in the development and homeostasis of human tissue. Aberrant regulation of this process is thought to cause numerous diseases, including developmental disorders, neurodegenerative disease, and cancer. Apoptosis is the main type of programmed cell death and is well understood. However, recent intensive studies have revealed other types of programmed cell death. Here, we include an overview of three types of programmed cell death: apoptosis, necroptosis, and autophagic cell death. We also provide information on damage-associated molecular patterns (DAMPs), which have pro-inflammatory effects and are reportedly associated with cell death. Finally, we discuss the link between programmed cell death and periodontal disease and propose a hypothetical role for programmed cell death and DAMPs—which are released from cytoplasm of necrotic cells—in periodontal disease initiation. (J Oral Sci 54, 137-149, 2012)
In a previous study, we evaluated the influence of periodontal treatment and physiological parameters on the subjective perception of mastication using the Oral Impact on Daily Performance Questionnaire (OIDP). In this study, we investigated the influence of periodontal treatment on the objective measures of masticatory performance in the same study sample. Patients with chronic periodontitis (n = 28) were examined on two occasions with a 45-day interval. Electrical activity of the masticatory muscles and maximum bite force were determined. In addition, masticatory performance was assessed using silicone impression blocks as test material. The median particle size of the chewed blocks was determined employing a sieving method. The number of teeth and the probing depth were also recorded. The probing depth was significantly reduced following treatment (P < 0.001). The median particle size of the chewed material was also reduced, which indicates a significant improvement in masticatory performance after treatment (P < 0.001). Bite force and muscle activity were significantly correlated both before and after treatment (P < 0.05). There was a negative correlation between masticatory performance and number of teeth (P < 0.05); moreover, individuals with a lower number of teeth exhibited poorer masticatory performance (P = 0.01). Periodontal treatment had a positive influence on masticatory performance 45 days after conservative treatment. (J Oral Sci 54, 151-157, 2012)
We investigated the relationship of the maxillary central incisors to the incisive papilla in wearers of complete dentures. First, image analyzer software was used to examine the relationship of the midpoint of the incisive papilla to the labial surface of the maxillary central incisors on occlusal photographs of 120 maxillary casts from dentate Malaysian adults. Then, an Alma denture gauge was used to identify the position of the labial surface of the maxillary central incisors in relation to the midpoint of the incisive papilla in complete dentures from 51 patients who requested replacement dentures at the Faculty of Dentistry, University of Malaya. The mean incisor distance to the incisive papilla in dentate adults was 9.59 ± 1.00 mm, while the mean incisor distance to the incisive papilla in complete dentures was 6.34 ± 1.87 mm. Thus, in our sample of edentulous patients, the anterior teeth in complete dentures were positioned approximately 3 mm closer to the incisive papilla, as compared with the position of the central incisors in natural dentition, and did not duplicate the position of the natural anterior teeth. (J Oral Sci 54, 159-163, 2012)
Podoplanin, a transmembrane sialomucin-like glycoprotein, is a specific marker of lymphatic vessels, and its expression is also considered to be associated with tumor invasion and tooth development. In this study, we examined the expression of podoplanin in calcifying cystic odontogenic tumor (CCOT) in comparison with that in other so-called hard α-keratin-expressing tumors such as craniopharyngioma (CP) and pilomatrixoma (PM). Immunohistochemical staining for podoplanin was carried out using surgical specimens of 15 CCOTs of the jaw, 19 CPs of the pituitary gland, and 15 PMs of the skin. Positivity for hard α-keratin was evident in ghost, shadow and transitional cells in all of these tumors (100%). The podoplanin expression in CCOTs was evident in the periphery of ameloblastoma-like epithelium (86.6%) and the epithelial cells adjacent to ghost cells (60%). On the other hand, in adamantinomatous-type CPs, podoplanin expression was observed in epithelial components corresponding to the stratum intermedium (100%), but not in the periphery of ameloblastoma-like epithelium (0%). In squamous-type CPs podoplanin was expressed in basal cells (100%), but all of the PMs were podoplanin-negative (0%). In the periphery of the ameloblastoma-like epithelium or basophilic cell layer, podoplanin was expressed more strongly in CCOTs than in CPs or PMs. These findings suggest that the expression of podoplanin in CCOTs may reflect rapid turnover of cytoskeletal filaments and local invasiveness. (J Oral Sci 54, 165-175, 2012)
Imbalanced bone remodelling associated with osteopaenic or osteoporotic conditions can lead to a net bone loss throughout the skeleton, including the oral cavity, possibly leading to tooth mobility. This study investigated possible associations between systemic bone mineral density and both tooth mobility and periodontal status in peri-menopausal women. Subjects comprised 119 dentate, peri-menopausal Indian women between 40 and 54 years old. Clinical parameters recorded were systemic bone mineral density (BMD), tooth mobility in terms of Periotest value (PTV score), clinical attachment loss (CAL), pocket depth (PD), plaque index (PI) and sulcular bleeding index (SBI). Statistical analysis was performed to assess correlations between PTV score and T-score. PTV score correlated significantly (P < 0.05) with T-score, PD and CAL. The partial correlation coefficient between PTV score and T-score after adjusting for confounders was -0.3676 (P < 0.05). Results of one-way analysis of variance showed a significant difference between mean PTV scores for osteoporotic, osteopaenic and normal patients. In this population of peri-menopausal women, systemic bone mineral density represented an independent factor associated with tooth mobility. (J Oral Sci 54, 177-182, 2012)
Toothbrushing is fundamental to oral hygiene. Children differ in manual dexterity and their grip on toothbrushes. We videotaped toothbrushing sessions and observed the grip type, duration of brushing, and brushing technique used among 100 children aged 8-12 years. We then investigated the association between grip type and plaque removal, using plaque scores obtained at various time points. We further examined the effect on plaque scores of standardizing both brushing technique and duration among the same participants. The most common grip was the distal oblique, followed by the oblique; the spoon and precision grips were rare, and no child used a power grip. Mean brushing duration for most children was 1.43 ± 0.85 min, and the most common brushing technique was horizontal scrubbing. We conclude that grip preference is inherent and that the distal oblique grip was better than the oblique grip in removing plaque. (J Oral Sci 54, 183-190, 2012)
This study aimed to compare the dental curriculum of the traditional six-year system with that of the new four-year (graduate-entry) system in South Korea. There are 11 dental schools in South Korea: six are public and five are private. Eight offer the new four-year program and the other three offer the traditional six-year program. Descriptive analyses were conducted using bibliographic data and local information along with statistical analyses such as chi-square tests. In the six-year programs, clinical dentistry subjects were taught almost equally in practical and didactic courses, while the basic science courses were taught more often as practical courses (P < 0.0001). In the four-year programs, both the basic science and clinical dentistry subjects were taught didactically more often; while more dentistry subjects were taught than basic sciences (P = 0.004). The four-year program model in South Korea is more focused on dentistry than on basic science, while both basic and clinical dentistry subjects were equally taught in the six-year program. (J Oral Sci 54, 191-196, 2012)
The published literature on tooth transposition includes only a few studies that have involved more than 50 subjects. The aim of the present study was to investigate the prevalence of true maxillary tooth transposition and possible associated dental anomalies in a larger sample of children. The dental records and radiographs of children who had been diagnosed as having true maxillary tooth transposition at a School Dental Clinic in Hong Kong were studied retrospectively. Data were analyzed for sex and side distribution, as well as for associated dental anomalies. Trends of differences were analyzed statistically using the Fisher exact or chi-squared test. A total of 69 cases of true maxillary tooth transposition were identified and studied; its prevalence in Hong Kong Chinese children was 0.81%. More females than males were affected, and the difference between the sexes was statistically significant (P < 0.05). The prevalence of congenitally missing teeth, microdontia of the maxillary lateral incisors or dental impaction was higher in patients with maxillary tooth transposition than in the general population (P < 0.05, P < 0.0005, and P < 0.0001, respectively). The fact that patients with maxillary tooth transposition were more likely to have congenital absence or microdontia of the maxillary lateral incisors lent further support to the contention that a developmental field defect plays a role in the pathogenesis of maxillary tooth transposition. (J Oral Sci 54, 197-203, 2012)
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