Introduction Cleft lip and/or palate (CL/P), the most prevalent congenital anomaly, has been associated with higher rates of child maltreatment. In particular, the presence of cleft lip has more of an impact on external appearance and may increase the risks of negative health outcomes such as parental postpartum depression; however, this concept remains controversial. Item #10 of the Edinburgh Postpartum Depression Scale is the assessment of parental self-harm ideation, and its presence in postpartum mothers merits risk assessments as an emergent issue that may affect the health of both mothers and infants. This study focused on the impact of CL/P on maternal self-harm ideation. Methods Of 100,300 live births from a nationwide birth cohort in Japan, 238 mothers of infants with CL/P [186 children born with cleft lip (CL ± P) and 52 born with isolated cleft palate (CP)] were included in the analyses. The prospective association of children with CL/P and maternal self-harm ideation, which were acquired using item #10 in the Edinburgh Postpartum Depression Scale at 1 and 6 months postpartum, was examined using binomial logistic regression analyses after multiple imputations and with adjustments for several maternal (age at delivery, smoking habit, and alcohol intake) and child-related (sex and prevalence of other congenital diseases) variables. Results The prevalence of self-harm ideation in 238 mothers of infants with CL/P at 1 and 6 months were 14.7% (35/238) and 18.8% (45/238) [8.2% (8,185/100,062) and 12.9% (12,875/100,062) in the control group], respectively. The odds ratio (95% confidence interval) for maternal self-harm ideation increased with CL/P prevalence [1.80 (1.22–2.65) and 1.47 (0.98–2.18)] at 1 and 6 months of age, respectively. After stratified by the prevalence of cleft lip, we found significant differences in the CL ± P group but not in the CP group. Furthermore, persistent self-harming ideation was associated with a higher risk in the CL ± P group [2.36 (1.43–3.89)]. Conclusion CL/P, particularly cleft lip, which is more noticeable externally, was associated with an increased prevalence of maternal self-harm ideation. The findings in this study indicate some potential benefits of increasing support for mothers who have infants with CL/P.

Otitis media, one of the most common childhood diseases, is characterized by inflammation or infection of the middle ear. Due to their ease of access, daily probiotics are recommended for the prevention of early childhood otitis media. This study aimed to assess the impact of probiotics on the incidence of otitis media using a dataset (n = 95,380) from the Japan Environment and Children's Study, a nationwide birth cohort study. After multiple imputations, the association between the incidence of otitis media in early childhood and the daily frequency of yogurt intake in children and mothers was examined using a generalized linear model after adjusting for several confounders. Repeated incidence of otitis media during the 2 years after birth was found in 14,874 participants (15.6%). Based on participants with the lowest frequency of yogurt intake ("almost never") as the reference group, risk ratios for otitis media incidence decreased with higher frequencies of yogurt intake in children at one year of age, but also independently in mothers during pregnancy. The lowest risk ratio (95% confidence interval) for otitis media incidence at six months of age was observed with the most frequent yogurt intake (once/day or more) (0.54 [0.46-0.63]). Additionally, although a similar association was observed in the subgroup of those with cleft lip and/or palate (CL/P), a high-risk group for severe recurrent otitis media, no statistical significance was observed. Thus, increased regular yogurt intake in both children and mothers was associated with a decrease of otitis media during early childhood.

BACKGROUND: Bruxism is defined as a repetitive masticatory muscle activity, characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Although the bruxism etiology can be bidirectionally described with sleep disorders, there are few studies available to understand the association of sleep duration with bruxism behavior in early childhood. METHODS: A dataset of children (n = 90,148) from the Japan Environment and Children's Study (JECS) - an ongoing nationwide, prospective birth cohort study - was used to investigate the prospective association of the infant's sleep duration with bruxism behavior, which were acquired using self-reported questionnaire. After multiple imputation of data, the association between sleep duration and bruxism behavior in early childhood was examined using a binomial logistic regression analysis. It was conducted with adjustments for several maternal (e.g., age at delivery and sleep duration) and child-related (e.g., sex and sleep position) variables. RESULTS: The prevalence of bruxism behavior at the ages of two and four were 16.2% and 22.5%, respectively. Using the shortest sleep duration group's participants (≤13 h) as the reference, the odds ratio (95% confidence interval) for prevalence of bruxism behavior decreased with longer sleep duration at one month of age, but not at 36 months of age, after covariate adjustments. Furthermore, in comparison with the impacts between daytime and nighttime sleep, nighttime sleep with longer duration were dominantly associated with bruxism behavior. CONCLUSION: The sleep duration in infant stage, especially during newborn stage was associated with the prevalence of bruxism behavior in children.

Abstract The gut environment, including the microbiota and its metabolites and short-chain fatty acids (SCFA), is essential for health maintenance. It is considered that functional recovery treatment for masticatory dysphagia affects the composition of the gut microbiota, indicating that habitual mastication, depending on the hardness of the food, may affect the gut microbiota and environment. However, the impact of chronic powdered diet feeding on the colonic condition and motility remains unclear. Here, we evaluated various colonic features in mice fed with powdered diets for a long-term and a mouse model with masticatory behavior. We observed a decreased abundance of the SCFA-producing bacterial genera in the ceca of the powdered diet-fed mice. Based on the importance of SCFAs in gut immune homeostasis and motility, interestingly, powdered diet feeding also resulted in constipation-like symptoms due to mild colitis, which were ameliorated by the administration of a neutrophil-depleting agent and neutrophil elastase inhibitors. Lastly, the suppressed colonic motility in the powdered diet-fed mice was significantly improved by loading masticatory activity for 2 h. Thus, feeding habits with appropriate masticatory activity and stimulation may play a key role in providing a favorable gut environment based on interactions between the gut microbiota and host immune system.

Cleft lip and/or palate (CL/P), the most prevalent congenital anomaly, is understood to negatively affect a wide range of child development. Since the concept remains controversial, because most published work is from cross-sectional studies, we examined the neurodevelopmental trajectories in participants with CL/P through a longitudinal comparison with the general population during early childhood using data from a nationwide birth cohort study in Japan. The linear mixed models for each domain of the Ages and Stages Questionnaire, third edition (ASQ-3), were used to detect differences in standardised mean scores between groups. The ASQ-3 is a general neurodevelopmental screening tool comprising communication, gross motor, fine motor, problem-solving, and personal-social domains. Participants' neurodevelopment was determined semi-annually from 6 to 36 months of age. The trajectories of standardised mean scores in each domain showed several significant differences between the control and CL/P groups, with the maximum difference at 24 months of age in the communication domain. Indeed, CL/P was associated with significantly lower scores in the communication (coefficient: -3.31, 95% CI: -5.09 to -1.14), problem-solving (coefficient: -3.13, 95% CI: -5.07 to -1.18), and personal-social domains (coefficient: -1.99, 95% CI: -3.87 to -0.11). Trajectories of ASQ-3 scores suggest neurodevelopmental delays in children with CL/P.

OBJECTIVES: Daily toothbrushing behaviour is very effective for the prevention of early childhood dental caries (ECC), but is mostly dependent upon parental management. Intrapersonal association between lower toothbrushing frequency and depression is well known; however, the impact of maternal postpartum depression on child toothbrushing behaviour within the mother-child dyad remains unknown. The aim of this study was to determine the association between the prevalence of maternal postpartum depression and lower toothbrushing frequency in children aged two years. METHODS: A secondary analysis of a data set from the Japan Environment and Children's Study was performed. A total of 104 062 fetuses were enrolled after obtaining informed written parental consent, in which 84 533 mother-infant pairs were included after applying exclusion criteria. The Edinburgh Postpartum Depression Scale (EPDS) was used to evaluate maternal postpartum depression (a total score of ≥9 in EPDS) at one and six months postpartum. Indeed, the participants were classified based on the persistence of postpartum depression: 'Resilient' (no prevalence); 'Improving' (prevalence only at one month postpartum); 'Emergent' (prevalence only at six months postpartum); and 'Chronic' (prevalence at both time points). The association between postpartum depression and a toothbrushing frequency in children (the reference group: more than once per day, the low group: once per day, and the very-low group: less than once per day) was examined using Poisson regression models with adjustments for maternal and child characteristics after multiple imputations for missing data. RESULTS: The prevalence of maternal postpartum depression at one and six months postpartum was 13.9% and 11.4%, respectively; the proportions of each persistence group were 81.1% ('Resilient'), 7.5% ('Improving'), 5.0% ('Emergent') and 6.4% ('Chronic'). Concerning children's toothbrushing frequency, 51.6% and 0.5% of participants self-reported frequencies of once per day and less than once per day, respectively. The association of maternal postpartum depression with a lower toothbrushing frequency in children consistently had higher relative risks (RRs). However, these associations were weakened when adjusting for whether the child could self-perform toothbrushing or whether this was done under parental supervision. A key result is that participants with persistent postpartum depression at both one and six month(s) postpartum showed the highest adjusted RRs (95% CI) for lower toothbrushing frequency in children (1.08 [1.04-1.12] with a decrease in children's toothbrushing frequency). CONCLUSION: Maternal mental health provides valuable screening information for children with lower toothbrushing frequency for the purpose of preventing ECC.

BACKGROUND: Daily toothbrushing prevents early childhood caries, but reinforcement depends on facilitative parenting behaviours. Mother-to-infant bonding, the maternal affection towards the infant, is an environmental factor that strongly influences parenting. AIM: This study examined the association between maternal bonding and children's daily toothbrushing frequency. DESIGN: The sample consisted of 83 954 mother-infant pairs at two years postpartum, derived from the initial sample of JECS (cohort study), which included 104 062 foetuses. Maternal bonding disorders were assessed using the Mother-to-Infant Bonding Scale (MIBS). After multiple imputation for missing data, a multinomial logistic regression analysis was conducted with adjustments for several maternal (eg, age at delivery) and child-related (eg, self-performed toothbrushing) variables. RESULTS: The odds ratio (95% confidence interval) for the association of maternal bonding disorders with the low (once per day) and the very low child toothbrushing frequency (<1 per day) was 1.12 (1.07-1.17) and 1.23 (0.91-1.66), respectively, after covariate adjustments. Furthermore, the univariate general linear model showed that the mean MIBS scores significantly decreased as the daily child toothbrushing frequency increased. CONCLUSIONS: The prevalence of maternal bonding disorders at one year postpartum was prospectively associated with a lower frequency of child toothbrushing at two years of age.

BACKGROUND: Cleft lip and/or palate is among the most prevalent congenital birth defects, and negatively affects maternal psychological status and may consequently result in higher prevalence of child maltreatment. However, the association of childbirths of infants with cleft lip and/or palate with maternal emotional involvement still remains unclear. We examined the association between childbirths of infants with cleft lip and/or palate and mother-to-infant bonding, using data from the Japan Environment and Children's Study, a nationwide birth cohort study. METHODS: A cross-sectional study using the jecs-an-20,180,131 dataset was performed. A total 104,065 fetuses in 15 regional centres in Japan were enrolled after obtaining informed written consent. The Mother-to-Infant Bonding Scale, a self-report scale consisting of 10 items, was used to evaluate maternal bonding at one year after childbirth. Finally, the participants consisted of 79,140 mother-infant pairs, of which 211 mothers of infants with cleft lip and/or palate were included in our analyses. Multivariable logistic regression analysis using multiple imputation for missing data was performed to calculate the odds ratio and 95% confidence interval in the estimation of the association between bonding disorders and childbirths with cleft lip and/or palate. RESULTS: No increased risk of bonding disorders was observed among all the mothers of infants with cleft lip and/or palate (odds ratio [95% confidence interval]; 0.97 [0.63-1.48], p = 0.880), however, advanced maternal age or multiple parity may adversely affect the associations between bonding disorders and cleft lip and/or palate, respectively. After stratification with a combination of maternal age and parity, a significant association of cleft lip and/or palate with bonding disorders was found only among advanced-age multiparae (odds ratio [95% confidence interval] = 2.51 [1.17-5.37], p = 0.018), but it was weakened after additional adjustment for maternal depression. CONCLUSIONS: Childbirths of infants with cleft lip and/or palate may increase the risk of bonding disorders among advanced-age multiparae, possibly through maternal depression. This finding provides valuable information for the provision of multidisciplinary cleft care.

BACKGROUND: Sports-related dental injuries, such as tooth fracture, loosening, and avulsion, are a major concern among young athletes because they directly impair oral function. Although the preventive efficacy of mouthguards has been well established, the prevalence of sports-related dental injuries remains high among young athletes. The aim of this study is to identify the variables contributing to the risk of sports-related dental injuries by conducting a survey on large population of young athletes in Miyagi prefecture. METHODS: A cross-sectional study was conducted with school-aged athletes (aged 6-15 years, n = 5735) using a self-reported questionnaire. The questionnaire examined general variables, including sex, age, and body mass index; sports-related variables, including sports-type, team level, activity schedule, break time, and verbal/physical abuse by coaches; and lifestyle variables related to free time, including screen-time and sleep duration. Their associations with sports-related dental injuries were examined using multivariate logistic regression models. RESULTS: The prevalence of sports-related dental injuries was 13.3% (763 of 5735 young athletes) and was higher in males (14.3%, 592 of 4132) than in females (10.7%, 171 of 1603; adjusted odds ratios [ORs] and 95% confidence intervals [CIs]: 1.48 [1.22-1.79], p < 0.001). After stratification according to sex, significant associations with the prevalence of sports-related dental injuries were evident for three variables-insufficient break time, verbal abuse, and physical punishment-in males (adjusted ORs [95% CI]: 1.35 [1.03-1.77], p = 0.032; 1.31 [1.05-1.62], p = 0.015; and 1.36 [1.06-1.75], p = 0.016, respectively) but not in females (adjusted ORs [95% CI]: 0.88 [0.53-1.47], p = 0.623; 1.29 [0.87-1.91], p = 0.206; and 0.97 [0.57-1.63], p = 0.894, respectively). CONCLUSIONS: Although our results might be based on the individual athlete's self-perception to the sports-related variables, our results suggest that insufficient break time, verbal abuse, and physical punishment from coaches are positively associated with the prevalence of sports-related dental injuries in young male athletes.

Root resorption lacunae are principally formed by odontoclasts. While these cells develop from the same origin as osteoclasts, odontoclasts normally have fewer nuclei and a less clear zone compared with osteoclasts. We therefore, hypothesized that odontoclasts possess less differentiation in matrix resorption characteristics than osteoclasts. To test our hypothesis, we compared the TRAP-positive area and the expression patterns of two important proteolytic enzymes, cathepsin K and matrix metalloproteinase-9 (MMP-9), between odontoclasts and osteoclasts. We focused on physiological root resorption in the rat molar, which is a useful experimental model for estimating odontoclasts and osteoclasts. Observations showed the number of nuclei and the TRAP-positive area of odontoclasts to be significantly less compared with osteoclasts. Using in situ hybridization and double labeling fluorescence in situ hybridization showed the majority of odontoclasts to express both cathepsin K and MMP-9, especially 4 and 5 weeks of age, when physiological root resorption occurs actively. Moreover, putative precursor cells of odontoclasts, which typically appeared in the middle of the periodontal ligament at 3 weeks of age, expressed both enzymes. In contrast, the majority of matured osteoclasts expressed only cathepsin K but not MMP-9. We suggest that odontoclasts are comparable to osteoclasts with less differentiation with regard to the expression of proteolytic enzymes.

I型コラーゲンは骨や結合組織,象牙質に豊富に含まれる線維状タンパクである。I型コラーゲンC-プロペプチドはコラーゲン分子への変換に伴って産生され,コラーゲン分子の会合とコラーゲン線維形成にとって必須である。近年,C-プロペプチド単体に様々な作用があることが報告され,特にin vitroにおいて硬組織形成に関与する前駆細胞の分化に抑制的に働くことが報告されている。つまり,硬組織の発達・形成過程での重要性が示されているが,in vivoにおけるC-プロペプチドの局在については明らかとなっていない。本研究では,抗I型コラーゲンC-プロペプチド抗体を用いた免疫組織染色を行い,骨および象牙質,セメント質といった硬組織領域における,それぞれの発現局在について調べ,抗I型コラーゲン抗体を用いたIHCとプロコラーゲンα2(I)鎖のcRNAプローブを用いたin situ hybridizationの結果と比較検討した。胎生期における下顎骨発生,および歯牙の発生過程におけるC-プロペプチドの局在から,骨,象牙質およびセメント質の活発な形成時期にはその基質において集積が認められた。くわえて,ヘルトウィッヒ上皮鞘周囲に認められたI型コラーゲンC-プロペプチドの集積の所見からも,すでに報告されている分化調節機構が骨組織のみならず,象牙質やセメント質の発達過程においても重要である可能性が示された。