The aim of this investigation was to study the effects of prolonged breast-or bottlefeeding on dental caries in Japanese infants. This longitudinal study was conducted by means of a questionnaire and clinical examination of 592 children at 18 months, 2 years and 3 years of age. The children were divided into three groups: 1) children still being breast-fed at 18 months of age (n‫;)24ס‬ 2) children still being bottle-fed at 18 months of age (n‫;)54ס‬ and 3) children weaned off of breast-or bottle-feeding and with no nonnutritive-sucking habits at 18 months of age (n‫.)502ס‬ Results showed that breast-feeding at 18 months of age produced many significant differences to the control children, including a higher prevalence of caries and higher number of dft. However, no significant differences were observed between bottle-fed and control children. In conclusion, our results suggest that prolonged breast-feeding at an early age before primary dentition has fully erupted is a risk factor for dental caries. Therefore, breast-fed children need to be monitored more closely, and aggressive methods of preventive care need to be instituted. It is also important to identify factors related to dental caries among breastfed children as soon as possible, and develop effective preventive programs.

Tobacco smoking is the main risk factor associated with chronic periodontitis, but the mechanisms that underlie this relationship are largely unknown. Recent reports proposed that nicotine plays an important role in tobacco-related morbidity by acting through the nicotinic acetylcholine receptors (nAChRs) expressed by non-neuronal cells. The aim of this study was to investigate whether alpha 7 nAChR was expressed in periodontal tissues and whether it functions by regulating IL-1 beta in the process of periodontitis. In vitro, human periodontal ligament (PDL) cells were cultured with 10(-12) M of nicotine and/or 10(-9) M of alpha-bungarotoxin (alpha-Btx), a alpha 7 nAChR antagonist. The expression of alpha 7 nAChR and IL-1 beta in PDL cells and the effects of nicotine/alpha-Btx administration on their expression were explored. In vivo, an experimental periodontitis rat model was established, and the effects of nicotine/alpha-Btx administration on expression of alpha 7 nAChR and development of periodontitis were evaluated. We found that alpha 7 nAChR was present in human PDL cells and rat periodontal tissues. The expressions of alpha 7 nAChR and IL-1 beta were significantly increased by nicotine administration, whereas alpha-Btx treatment partially suppressed these effects. This study was the first to demonstrate the functional expression of alpha 7 nAChR in human PDL cells and rat periodontal tissues. Our results may be pertinent to a better understanding of the relationships among smoking, nicotine, and periodontitis.

Background and Objective:  The purpose of this study was to determine the time of infection by anaerobic gram‐negative rods associated with periodontal disease, and to clarify their transmission from mother to child. Material and Methods:  Seventy‐eight Japanese children (including 10 siblings), aged from 3 to 9 years, and 68 mothers, were enrolled in this study. Colonization by 11 periodontal bacterial species was determined using polymerase chain reaction amplification of samples of subgingival plaque obtained from the children and their mothers. Results:  The detection rates of Porphyromonas gingivalis, Tannerella forsythensis and Treponema denticola increased in children after the age of 6 years. We found a high consistency in colonization by P. gingivalis, T. denticola, Prevotella intermedia and Prevotella nigrescens in 9 of the 10 siblings. The average number of bacterial species in plaque samples harboring Fusobacterium nucleatum and/or Fusobacterium periodonticum was significantly greater than in those without, in both children and mothers. Kappa statistical analysis revealed that the detection of Capnocytophaga gingivalis, Capnocytophaga ochracea, Campylobacter rectus and T. denticola in children was consistent with that in the mother. Conclusion:  Periodontal bacterial colonization in Japanese children increased with age and was associated with F. nucleatum and/or periodonticum, and the bacterial flora in children was similar to that in their mothers.

The aim of this study was to investigate the characteristics and risk factors of prolonged breast-feeding in children. A total of 105 children aged 18 months were screened for ongoing breast-feeding at a public health center. Of these, 105 children were selected for a more comprehensive examination, involving investigation of dietary, tooth-brushing habits and oral hygiene. The children were examined again, and initial and manifest caries were recorded at 24 months of age. As a result, 20 (19.0%) of the 105 children had caries at 24 months of age. Logistic regression analysis revealed an association between caries and bedtime breast-feeding (p‫.)300.0ס‬ Oral hygiene at 18 months of age was also correlated with caries (p‫.)510.0ס‬ It was concluded that reducing the frequency of feeding, early establishment of good oral hygiene habits and also regular visits to the dentist are essential in preventing nursing caries in prolonged breast-fed children.

A rare case of birooted primary canines is reported. A male patient aged 6 years 4 months of age presented with pain and swelling related to the upper right first primary molar. Radiographic examination revealed an incidental finding of bifurcation of the roots of all four primary canines. This represents a rare finding. The prevalence of birooted permanent canines in the Japanese population has been reported, but the prevalence of this abnormality of primary canines in other populations is unknown. This report discusses the findings in the context of the available literature. The possible aetiology, possible inferences for the developing dentition, and the need for careful assessment prior to root canal therapy or extraction are highlighted.