Journal of Dental Medicine

Statement of Problem: In some cases, a difference in size between the right and left teeth, during band selection for first molars, is observed.

Purpose: The aim of this study was to measure the mesiodistal width and to compare the teeth on left and right sides of jaws in individuals with normal occlusion, according to the sex.

Materials and Methods: In this cross-sectional study, sixty students (30 males and 30 females), age ranging from 16-18 with the mean age of 17.3, were selected through cluster random sampling from Mashhad high schools. The mesiodistal width of 1440 teeth, from the distal of first molar on right side to the distal of first molar on the left, were measured on study casts. Data were analyzed using paired t-test and Independent sample t-test.

Results: In upper jaw, mean of the mesiodistal width of each tooth on the right side was less than its counterpart on the left side except for the right second premolar which its width was more than that of the left one although the differences were not statistically significant. In lower jaw, mean of the mesiodistal width of each tooth on right side was more than the same tooth on the left except for the canines and second premolars. The differences were not significant. Generally the mesiodistal width of each tooth in males was more than its counterpart in females with a specially significant difference for canines and first molars.

Conclusion: According to this study, there was a little difference in me siodistal width of teeth between the left and right sides. In upper jaw, the majority of teeth on the right side were smaller than the left ones whereas in lower jaw the right side ones were larger than the left ones. Therefore, dental asymmetry in both jaws, on the left and right sides, were opposite. Comparing males and females, each tooth in males was larger than the same one in females and especially for canines and first molars the difference was significant. As a result dental asymmetry should be considered in orthodontic treatments.

Background and Aims: Nursing Caries (NC) is a destructive form of caries because of incorrect nutritional habits in infants that affects deciduous teeth after eruption. Familiarity with the pattern of this type of caries and evaluation of its symmetrical or asymmetrical pattern is necessary for effective and scientific diagnosis and treatment. The aim was to assess the symmetrical or asymmetrical aspects of Nursing Caries in children between 3-5 years old.

Materials and Methods: In this cross-sectional study, 10 kindergartens were randomly selected by the Tehran Welfare Organization. 115 children with NC caries entered to study after examination. Written consents were obtained from the parents. The dmfs in upper primary incisors and upper and lower primary canines, as well as the first primary molars were assessed and the caries pattern in terms of symmetrical or asymmetrical aspects was evaluated. The data were analyzed by ANOVA, LSD, Chi-square and Fisher tests.

Results: In 53.9% of the children with NC, the anterior teeth were affected symmetrically, while 46.1% indicated an asymmetrical pattern. In general, 32.2% of the teeth were affected in a symmetrical pattern and 67.8% of them in an asymmetrical pattern. About the relationship between the breastfeeding from the right or left breast and the symmetrical pattern of the NC, 51% of the children were equally breastfed from both breasts. However, in the asymmetrical NC pattern with more impact in the right side of dentition, 50% of the children had been breastfed from the left side and in children with more caries  in the left side of dentition, 50% of them had been breastfed from the right side (P=0.01).

Conclusion: NC has symmetrical and asymmetrical patterns. Direction of mother for breastfeeding affects the symmetrical and asymmetrical pattern of NC.