According to the results of the present study, the Enterobacteriaceae were more prevalent in the oral cavities of children with nail-biting habits than in children with no oral habit.

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The purpose of this study was to determine the possible effect of genetic factors on Bolton tooth-size discrepancy. Subjects who applied for orthodontic treatment and their siblings (106 females and 78 males) were included in the study. The ages of the subjects ranged from 13 to 21 years. The siblings were grouped according to gender: male-male (24 pairs), female-female (38 pairs) and male-female (30 pairs). Mesio-distal tooth size was measured using a pair of dividers with fine tips, and Bolton anterior and overall ratios were calculated. The effect of heritability on Bolton ratios was studied by means of Harvey's mixed model least-squared and maximum likelihood computer program (LSMLMW) model type II. Statistical analysis showed that heritability was effective on Bolton tooth-size discrepancy in all groups except the male-female group. Siblings of the same gender showed high heritability for anterior and overall ratios, but no statistically significant difference was observed in the siblings of different gender.

The purpose of the present study was to examine and compare cervicovertebral morphology in subjects with different sagittal skeletal patterns. The material comprised lateral head films of 90 untreated subjects, 45 girls and 45 boys, aged 13-15 years. The radiographs were obtained in the natural head position using a fluid level method. The subjects were divided into three groups according to ANB angle: ANB angle between 1 and 5 degrees (skeletal Class I), larger than 5 degrees (skeletal Class II), and smaller than 1 degree (skeletal Class III). Each ANB group consisted of 30 subjects, 15 girls and 15 boys. Twenty-nine linear and four area measurements were used to assess cervicovertebral morphology. Differences between the ANB groups and between genders were assessed by means of analysis of variance and the least significant difference test. In addition, cephalometric measurements for all subjects were subjected to discriminant analysis. The results of the analysis of variance showed that there were statistically significant differences in the measurements of the lumen length of C1, inferior depths of C2 and C4, anterior intervertebral spaces of C2 and C3, posterior intervertebral space of C3, and anterior and posterior body heights of C4 among the ANB groups. The total length of C1, inferior depths of C2-C5, anterior intervertebral spaces of C2-C4, posterior intervertebral space of C2, anterior body heights of C4 and C5, and posterior body heights of C3-C5 demonstrated significant gender differences. The results of the discriminant analysis indicated that 54.4 per cent of the original grouped cases were correctly classified in the total sample. The final discriminant model was able to classify correctly 20 of the 30 Class I subjects (66.7 per cent), 17 of the 30 Class II subjects (56.7 per cent), and 12 of the 30 Class III subjects (40.0 per cent).