Biomedical subjects

Takuro Yonezu

Publications and source records attributed to Takuro Yonezu.

5 recordsLinked to original sources

PubMed2006

The relation between tooth shape ratio and incisor arrangement in Japanese children.

To investigate whether the relationship between tooth shape ratio and incisor arrangement proposed by Peck et al. in 1972 was applicable to Japanese children, we compared two groups, one with normal permanent dentition and another with crowded permanent dentition, using chronologically constructed plaster dentition models. Tooth shape ratio was obtained by dividing the incisor mesio-distal width by the labio-lingual width and then multiplying the result by 100. The results revealed a significant difference in the coronal mesio-distal diameter of the incisors between the two groups, but the other items showed no significant differences, suggesting no clear relationship between tooth shape ratio and incisor arrangement. That was, our results suggest that there is no clear relationship between tooth shape ratio of the mandibular incisors and arrangement of the permanent incisors in Japanese children.

Adolescent↗

PubMed2003

Tooth size-arch length relationships in the deciduous dentition: a comparison between contemporary and historical samples.

In a recent study, it was reported that maxillary and mandibular arch lengths were significantly shorter in a sample of contemporary children in the deciduous dentition compared with a historical sample from about 50 years earlier. The purpose of this study was to describe secular changes that might have occurred in tooth sizes and tooth size-arch length relationships in the same cohorts of contemporary and historical North American white children in the deciduous dentition. The 2 samples were similar in terms of geographic location, racial and ethnic backgrounds, and socioeconomic status. Both samples were restricted to white children with a normal overjet (<4 mm) and a normal anteroposterior molar relationship, no anterior open bite, and no crossbite. In addition, subjects were excluded if any permanent teeth were erupted. Measurements of mesiodistal tooth sizes and arch lengths of maxillary and mandibular arches were made, and tooth size-arch length discrepancies (TSALD) were determined. The results indicated that tooth sizes were generally similar in the 2 cohorts but slightly larger in contemporary children. Crowding, as measured by TSALD, was found to be common in the mandibular arch for contemporary children in the deciduous dentition of both boys and girls. Moreover, crowding was much more common and severe in contemporary children compared with children in the historical cohort. Further research is needed to determine whether the increase in mandibular crowding in the deciduous dentition will continue to be observed in the mixed and permanent dentitions and to further establish these possible secular trends.

Cephalometry↗

PubMed2002

Tooth wear patterns in the deciduous dentition.

Tooth wear is common in the deciduous dentition. A recent study suggests that tooth wear in the deciduous dentition is related to subsequent tooth wear in adults, so that early identification of factors related to tooth wear could be of long-term benefit. The purposes of this study were to describe patterns of tooth wear in the deciduous dentition and to relate tooth wear to occlusal characteristics and longitudinal dietary patterns. Data were collected as part of a longitudinal study of a cohort of children recruited at birth from Iowa hospitals. Stone casts were obtained in the deciduous dentition stage, and 355 children, 4 to 5 years old, met the selection criteria. Tooth wear was categorized for each tooth as none, mild, moderate, or severe, and related to occlusal characteristics and longitudinal data on fruit juice and soft drink consumption. All children exhibited some tooth wear on at least 1 tooth, and nearly 16% of them had at least 1 tooth with severe wear. Tooth wear was generally more severe in the maxillary arch and the anterior teeth. Severe tooth wear on the molars was significantly related to posterior crossbites, but severe tooth wear on the incisors was related to Class III canine relationships. There were no statistically significant relationships between tooth wear and soft drink or fruit juice consumption. Based on our results, we concluded that mild tooth wear is universal in the deciduous dentition, but only a few occlusal factors are related to severe tooth wear. Tooth wear was not related to any dietary patterns we investigated.

Analysis of Variance↗

PubMedDate not supplied

Interdental spacing and caries in the primary dentition.

PURPOSE: This study assessed the relationship between interdental spacing patterns and caries experience in the primary dentition. METHODS: Caries examinations were conducted amoung 356 children 4 to 6 years of age. At the time of the examinations, alginate impressions were obtained and poured in yellow stone. From the stone casts, each interdental area was categorized as: (1) space > 1 mm, (2) space < 1 mm, (3) no space, teeth in contact, or (4) no space, teeth overlapped. These categories were collapsed into presence or absence of space for each interdental site, and counted for each individual. Analyses assessed the relationships between interdental spacing and caries experience with separate analyses for anterior spacing, posterior spacing and total spacing. RESULTS: Children with more total interdental spaces had less decay experience and less untreated decay than children with fewer interdental spaces, and children with more molar spacing had less molar decay experience; however, these relationships were weak. Correlation analyses demonstrated significant relationships between number of decayed surfaces and total number of interdental spaces (r=-0.11, P=.04) and number of molar sites with interdental spaces (r=-0.13, P=.02). Multivariate analyses revealed the total number of interproximal spaces to be weakly associated with interproximal caries experience, but that fluoride exposure was a much stronger predictor. CONCLUSIONS: Absence of interdental spaces is weakly associated with greater decay experience in the primary dentition.

Chi-Square Distribution↗

PubMedDate not supplied

Effects of nonnutritive sucking habits on occlusal characteristics in the mixed dentition.

PURPOSE: Little is known about the extent to which nonnutritive sucking habits contribute to malocclusion in the mixed dentition. The purpose of this study was to report on the relationship between certain occlusal traits in the mixed dentition and longitudinal sucking behaviors. METHODS: Dental examinations were conducted on 630 children in the mixed dentition who participated in a large, ongoing longitudinal study. Five hundred eighty consented to impressions, and 524 adequate study models were obtained. Of these, 444 also had adequate longitudinal nonnutritive sucking data obtained via mailed questionnaires to parents at 3- to 6-month intervals from birth to 8 years. Sucking behaviors were grouped by predominant type and duration. Study models were hand articulated using wax bites to evaluate the occlusion for the presence of open bite, crossbite, molar relationship, and excessive overjet. Bivariate statistical analyses related presence of these malocclusions to sucking duration and type. RESULTS: Fifty-five percent of the children had malocclusions (anterior open bite, posterior crossbite, bilateral Class II molar relationship, or overjet >4 mm). Class II molar relationship was most common (30%). Overall, anterior open bite and posterior crossbite was associated with habits of 36 months or more. Sustained pacifier habits, including those of 24 to 47 months, were associated with anterior open bite and Class II molar relationships, while digit habits were associated with anterior open bite when sustained for 60 months or longer. CONCLUSIONS: Malocclusions are quite prevalent in the mixed dentition, and anterior open bite and posterior crossbite may be preventable by modifying nonnutritive sucking behaviors.

Chi-Square Distribution↗