BackgroundMolar incisor hypomineralization (MIH) frequently occurs in children worldwide. However, MIH prevalence throughout Japan has not yet been investigated. The purpose of this study was to clarify MIH prevalence rates and to consider potential regional differences throughout Japan.MethodsA total of 4496 children aged 7–9 years throughout Japan were evaluated in this study. MIH prevalence rates among children were evaluated in eight regions throughout Japan. A child’s residence was defined as the mother’s residence during pregnancy. The localization of demarcated opacities and enamel breakdown was recorded on a standard code form using a guided record chart. Logistic regression analysis was used to evaluate whether MIH prevalence rates differed among age groups, sex, and regions.ResultsThe overall prevalence of MIH in Japan was 19.8%. The prevalence of MIH was 14.0% in the Hokkaido region, 11.7% in the Tohoku region, 18.5% in the Kanto Shin-Etsu region, 19.3% in the Tokai Hokuriku region, 22.3% in the Kinki region, 19.8% in the Chugoku region, 28.1% in the Shikoku region, and 25.3% in the Kyushu region. These regional differences were statistically significant. Moreover, MIH prevalence rates decreased with age. No significant sex differences in MIH prevalence rates were demonstrated.ConclusionsTo our knowledge, this is the first MIH study carried out in several regions throughout Japan. Regional differences existed in MIH prevalence rates; particularly, MIH occurred more frequently in children residing in southwestern areas than those in northeastern areas of Japan.
While the need for caregivers' brushing have increased, the appropriate brushing motion is still unclear. The aim of this study was to clarify the gender difference of brushing motions between self-brushing and caregivers' brushing.Tooth brushing motions of 15 male and 20 female dental professionals were analyzed using a three-dimensional accelerometer and a strain tension gage. They brushed the buccal surfaces of the right lower molars using two brushing situations. Multilevel model analysis was applied in this study.Concerning self-brushing, gender difference was significant in cycle duration, buccal-lingual motion and brushing force, whereas for caregivers' brushing, a significant difference was observed only in the brushing force. In addition, the brushing force during caregivers' brushing was significantly greater than that of self-brushing on both genders.This study clearly demonstrated gender difference of brushing motion and force. Furthermore, a significant difference between self-brushing and caregivers' brushing was also evident. These results might contribute to improving the caregivers' brushing.
Aim: Because of the developing fine motor function of children, caregivers are encouraged to brush children's teeth for them until they develop the skills to do so themselves. However, appropriate techniques for caregivers'-toothbrushing haven't been clarified. This study evaluated the self-toothbrushing and caregivers'-toothbrushing motions of dental hygienists and mothers.Design: Twenty female dental hygienists and twenty mothers participated in this study. A dental model of deciduous dentition attached to a dental education mannequin was used for caregivers'-toothbrushing with a manual toothbrush. Three-dimensional (3D) motions and forces were recorded using a toothbrush attached with a 3D accelerometer and a strain tension gage. The data were evaluated between the abovementioned two groups.Results: Dental hygienists demonstrated faster motion with lighter force than mothers during tooth brushing. Additionally, in caregivers'-toothbrushing, the displacement of toothbrush of dental hygienists was significantly shorter than that of mothers. Regarding the intra-individual correlations between self-toothbrushing and caregivers'-toothbrushing, significant correlations were found on the displacement of toothbrush for both groups.
Conclusion:Dental hygienists might change their instructions on the brushing motion for caregivers'-toothbrushing whereas the caregivers'-toothbrushing by mothers is strongly reflected by the characteristics of self-toothbrushing. These findings might contribute to establishing tooth brushing instructions for mothers.
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