The effect of exposure to amoxicillin on tooth development remains to be elucidated. The purpose of this study was to investigate the effect of amoxicillin on rat incisor odontogenesis. Male Wistar rats weighing approximately 100 g were given a single intraperitoneal injection of 3.0 g/kg body weight amoxicillin. One week after injection, the rats were fixed, and the lower incisors were demineralized and prepared into paraffin sections for light microscopy (LM) and immunohistochemistry. Undemineralized samples were embedded in resin and ground for processing for contact microradiography (CMR) and scanning electron microscopy (SEM). Serum calcium, phosphate, and magnesium concentrations were measured. At 1 week after amoxicillin administration, LM, CMR, and SEM revealed a clear increase in the area of interglobular dentin, representing disruption of mineralization by odontoblasts. Immunohistochemistry demonstrated moderate levels of the small integrin-binding ligand N-linked glycoprotein family dentin matrix protein 1 in large areas of interglobular dentin. On the other hand, no morphological alteration or hypomineralization was observed in the enamel. Serum calcium values showed no significant differences between the control and experimental rats during the experimental period although both serum phosphate and magnesium levels increased at day 1 after amoxicillin injection. The results suggest that a single dose of amoxicillin specifically affects normal tooth dentin mineralization, but not enamel mineralization in rat incisor odontogenesis. The present results further our understanding of the clinical association between dentin abnormality and amoxicillin exposure during tooth development.

The biochemical composition of the internal and external basal laminae in the junctional epithelium differs significantly, and the precise cellular origin of their respective molecules remains to be determined. In the present study, the expression and localization of three basement membrane-specific molecules-laminin 5 (γ2 chain), type IV collagen (α1 chain), and laminin 10 (α5 chain)-and one tooth-specific molecule, amelotin, was analyzed in adult murine gingiva by using in situ hybridization and immunohistochemistry. The results showed that the outermost cells in junctional epithelium facing the tooth enamel strongly expressed laminin 5 mRNA, supporting the immunohistochemical staining data. This suggests that laminin 5 is actively synthesized in junctional epithelial cells and that the products are incorporated into the internal basal lamina to maintain firm epithelial adhesion to the tooth enamel throughout life. Conversely, no amelotin mRNA signals were detected in the junctional epithelial cells, suggesting that the molecules localized on the internal basal lamina are mainly derived from maturation-stage ameloblasts. Weak and sporadic expression of type IV collagen in addition to laminin 10 in the gingiva indicates that these molecules undergo turnover less frequently in adult animals.

The primary aim of this study was to determine the prevalence of dental caries and its association with infant feeding and oral health-related behavior in Japanese children between the ages of 18 months and 3 years. A total of 387 infants were initially examined at the age of 18 months (or 19 months in some cases) and then again at 3 years (or at 3 years 1 month in some cases). The primary objective was to identify factors contributing to the prevalence of caries in children aged 18 months. The secondary objective was to follow up children with no caries at the age of 18 months to seek potential correlations between background factors and the increment of caries by the age of 3 years. In an adjusted multivariate logistic regression model, children who continued breastfeeding were approximately 7 times more likely to have dental caries at 18 months of age than those who did not. Infants brought in for an oral examination and consultation at around 12 months of age were less likely to develop dental caries at 18 months of age than those who were not. Multivariate logistic regression analysis revealed that infants who did not receive a dental check-up at 12 months of age showed a significantly higher incidence of dental caries at 3 years of age. The present results suggest that prolonged breastfeeding is a risk factor for early childhood caries at 18 months of age, and that infants in whom a regular oral care program is implemented from the age of 12 months are less likely to develop early childhood caries at 18 months or 3 years.

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 bottlefeeding, 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.

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.