Sexual dimorphism of primary dentition in Spanish children

How teeth can be used to estimate sexual dimorphism? A scoping review

INTRODUCTION

Teeth are biological structures with a high degree of hardness, density, calcification, and capacity to adapt to extrinsic factors at physical, biological, and physiological levels. Subsequently, they resist for a longer period in deteriorating environmental conditions. With dental analysis, it is possible to acquire biographical data about a person. The aim of this scoping review was to identify publications using human teeth tissues to estimate sexual dimorphism.

METHODS

The scoping review was carried out in the following databases: Jstor, Scielo, Science Direct, PubMed, and Scopus, using ten search strategies in English and guaranteeing completeness and reproducibility of the phases stipulated in the PRISMA guide.

RESULTS

143 studies on sexual dimorphism based on dental tissue traits were included, of which 40.6% (n = 58) were done in Asia and 27.2% (n = 39) in America. 80% of the studies (equivalent to 114 articles) focused their observations and measurements on the dental crown; 4.2% in enamel, dentin, and pulp together; 3.5% in dental pulp; 2.1% in the entire tooth; 2.8% in enamel, root, and the enamel-cementum junction, and only 0.7% in dentin and pulp. In addition, 92.3% of the studies used metric methods, while only 4.9% and 2.8% used biochemical and non-metric method respectively.

CONCLUSION

For sexual dimorphism establishment, enamel has been the most analyzed dental tissue in permanent canines and molars mainly. Likewise, the most widely and accurately used methods for this purpose are the metrics, with the odontometry as the most implemented (intraoral or by using dental plaster models, digital scanning or software) with prediction percentages ranging from 51% to 95.9%. In contrast to biochemical methods, that can achieve the highest precision (up to 100%), the non-metric methods, to a less extent, reported prediction percentages of 58%.

Secular changes in eruption of primary teeth in Chinese infants and young children from three national cross-sectional surveys

The eruption of primary teeth is a basic event during physical development of children, which is affected by heredity and environment. This study aimed to analyze the changes in primary teeth eruption among Chinese children with social development. A total of 249,264 healthy children under 2 years were extracted from the 1995, 2005, and 2015 National Survey on the Physical Growth and Development of Children in Nine Cities of China. Their primary teeth were examined and percentiles of primary teeth eruption age were calculated by probit analysis. The median primary teeth eruption age were 6.8 months, 6.7 months, 6.6 months in 1995, 2005 and 2015. Primary teeth eruption age of boys was 0.2 months, 0.3 months, 0.3 months earlier than that of girls in 1995, 2005 and 2015. Primary teeth eruption age was the earliest in children from northern region and was the latest in children from southern region, and this regional difference did not change over time. These findings suggest that primary teeth eruption age slightly advanced with social development, and their gender difference and regional difference have always existed, which supplied some data for understanding the secular trend of primary teeth development in stomatology, pediatrics, anthropology, and other related fields.

Wich factors influencing the number of teeth at 12 months of age: a birth cohort study

This study aimed to verify, through a longitudinal follow-up, the pre-, peri- and postnatal factors associated with the eruption of deciduous teeth. The study was nested in a Birth Cohort Study conducted in Pelotas, a Southern Brazilian city. Mothers were followed prenatally and their children were followed-up perinatally, at 3 and 12 months of age. The outcome was the number of teeth at 12 months, and exploratory variables included maternal habits and characteristics, anthropometric measures of children and mothers, and socioeconomic and demographic information. Data were collected through interviews with the mother and children's clinical exam. Poisson regression models were used for the analysis. Participants included 4,014 children with a mean number of erupted teeth at 12 months of 5.50. After adjustments, a lower mean number of teeth was observed in children from non-white mothers, early preterm children, and shorter children at birth and at 12 months. A higher number of teeth was observed for mothers with excessive weight gain during pregnancy, mothers who smoked during pregnancy, weightier children at birth and at 12 months, and for children with larger heads at birth and at 12 months. Our findings suggest that maternal and children characteristics influenced primary tooth eruption.

Emergence stages of permanent teeth in twins: A comparative study

BACKGROUND

The relative effects of genetic factors on the timing of tooth eruption can be demonstrated through twin studies; however, twin studies on the eruption time of permanent teeth were limited.

AIM

To compare the emergence stages of permanent teeth in twins and non-twin children.

DESIGN

A total of 480 patients aged from 5.0 to 13.11 years who attended to the Department of Pediatric Dentistry for any dental reason were included in the study. Twins were compared with the control group in terms of the emergence stages for all permanent teeth.

RESULTS

At the age of 5 years, girls in the control group showed statistically significant differences related to the central incisors, the first molars in the mandibular dentition and the first molars in the maxillary dentition, showing more advanced emergence stages. In the 6- to 8- and 12- to 13-year-old age groups, no gender-related differences in emergence stages were observed. Gestation age was found to have a statistically significant effect on the emergence stages of permanent teeth. There were no statistically significant differences between birthweights and tooth emergence stages in twins.

CONCLUSION

Longitudinal studies are needed to determine whether there is a strong genetic effect on emergence stages of permanent teeth in twins.