Biological predictors of mandibular asymmetries in children with mixed dentition.

OBJECTIVES: The objective was to investigate the severity of skeletal mandibular asymmetry in children with mixed dentition and other factors associated with asymmetry. METHOD: The study was cross sectional, with stratified sampling according to malocclusion type consisting of 205 subjects with mixed dentition (median 10, interquartile range 9-11 years). There were 59 subjects presenting Class II/1, 77 Class II/2, and 69 Class III. The mandibular asymmetry has been estimated from orthopantomograms using the Habets' method and the dental maturation by Demirjian's method. The sagittal skeletal relationship and facial growth pattern were assessed from lateral cephalograms. RESULTS: Asymmetries in general, were not rare and were more present in the condylar height rather than in the height of the ramus. The highest severity of condylar asymmetry was in Class II/2 subjects (median of asymmetry index 7.3; 64% subjects exhibiting moderate and severe asymmetry), while the Class III subjects exhibited the highest severity of both ramus and total height asymmetry (2.1; 13% and 2.0; 15%, respectively). Multiple logistic regression unveiled male gender as the only predictor of moderate or significant overall asymmetry. Dental age, the difference between dental and chronological age, and facial growth pattern were not significant predictors of asymmetries. DISCUSSION: Overall, asymmetries in mixed dentition cannot be considered rare; however, no strong relationships between asymmetry and observed biological factors were found.

Secular trend of earlier onset and decelerated development of third molars: evidence from Croatia.

The purpose of this study was to evaluate the influence of the secular trend on development of third molars in 30 years period in Littoral region of Croatia. A total of 1103 panoramic radiographs of subjects aged from 6 to 18 years were analysed. First group comprised 531 panoramic radiographs (258 girls) taken from year period 1977 till 1979 and second group 572 radiographs (325 girls) taken from year period 2007 till 2009. Demirjian's method was used to determine the developmental stage of third molars. A secular trend in 30 years period was observed as earlier onset of third molars development in boys (6 months on average maxillary and 11 months mandibular) and girls (6 months for maxillary and 4 months for mandibular). Now-a-days, an increase in mineralisation for one Demirjian stage occurs at a slower pace of 5.2 months in boys and 3.4 in girls in maxilla and 2.3 or 2 months in mandible for boys and girls, respectively. The study showed a secular trend present as earlier onset but decelerated development of third molars in both genders and both jaws.

Secular trend in the development of permanent teeth in a population of Istria and the littoral region of Croatia.

The study evaluated secular trends in dental development during a period of 30 years, correlation between dental and chronological age in Istria and the littoral region of Croatia. The sample consisted of 1000 panoramic radiographs of children, aged 6-16 years (mean 10.0±1.8), taken in the period 1977-1979 (N=500; 243 females) and 2007-2009 (N=500; 299 females). Dental age was assessed according to Demirjian's method. Correlation between chronological and dental age was linear, positive, high, and statistically significant in both periods and genders, ranging from 0.73 to 0.86. Dental age was underestimated when compared to chronological age by 1 year on average, more 30 years ago (-1.35±1.17) than today (-0.63±1.09), less for girls (-0.80±1.22) than boys (-1.21±1.10). A statistically significant positive secular trend in acceleration of dental development was present of 0.72 years during the 30-year period and was more significant in girls than boys (0.83- and 0.51-year acceleration).

The reliability of chronological age determination by means of mandibular third molar development in subjects in Croatia.

The aim of this study was to determine the development of the mandibular third molar and its relation to chronological age. The evaluated material consisted of 979 orthopantomograms of patients of Croatian Caucasian origin aged between 5.7 and 14.6 years. Third molar developmental stages were evaluated according to the stages proposed by Nolla. The frequencies of different stages of mineralization and the mean value of the mineralization of the mandibular third molars with regard to age, gender, and size of the mandible were determined and the coefficient of correlation determined between the age of the subject and the stage of development of the mandibular molars. Statistically significant correlation was determined between mineralization of the mandibular third molar and chronological age of the subjects (boys, mandibular left third molar r = 0.779, right third molar r = 0.793; girls, mandibular left third molar r = 0.746, right third molar r = 0.725). It can be concluded that the accuracy of age estimation based on Nolla's method is applicable for Croatian children.

Presence of third molar germs in orthodontic patients with class II/2 and class III malocclusions.

The aim of this study was to determine the presence of third molar germs in patients with Class II/2 and Class III malocclusions. The study comprised 146 examinees from Zagreb and Istria. Examinees with Class II/2 malocclusions amounted to 77 and those with Class III 69. With regard to development of dentition the examinees were divided into two groups: Group I subjects with early mixed dentition (23 subjects with Class II/2 and 21 subjects with Class III), and Group II subjects with late mixed dentition (54 subjects with Class II/2 and 48 subjects with Class III). Assessments were made from panoramic radiographs and lateral cephalograms. The Pearson chi2-test and Fisher's exact test was used to determine statistical significance in differences. Assessments showed that third molar germs were present significantly more often in the upper jaw in Class II/2 (58% vs. 44%) and in the lower jaw in Class III (83% vs. 69%). In subjects with Class II/2 all third molar germs were present statistically more often in late mixed dentition, which was also determined for maxillary third molar germs in Class III. The presence of mandibular third molar germs in Class III examinees was almost equal in both periods of mixed dentitions. The study confirmed correlation between the presence of third molar germs and sagital maxillomandibular relationship and encourages investigation of the differences in calcifications of all permanent teeth in such malocclusions.

Teeth eruption in children with normal occlusion and malocclusion.

The aim of this study was to assess the differences in eruption of permanent teeth (C, P1, P2 and M2) in a group of children with and without malocclusion. A sample of 1758 children (921 boys and 837 girls), aged 8-13 was randomly selected. The subjects were grouped by chronological age (11 groups) and by presence of malocclusion. Statistically significant differences were found for both, upper and lower canines in the age group 11 (p<0.01). Statistically significant difference was found in the age group 8.5 for upper first (p<0.05), upper second premolars (p<0.01) in the age group 10, and the lower second premolars in the age group 11 (p<0.05). Premature loss of deciduous teeth caused early eruption of succedaneus permanent teeth, possibly leading to development of a malocclusion.

Correlation between the pattern of facial growth and the position of the mandibular third molar.

PURPOSE: The purpose of this study was to examine the correlation between variables that determine the position of the third molar (M3) and correlation between the pattern of facial growth and examined variables. MATERIALS AND METHODS: Material for the study consisted of 130 panoramic radiographs and lateral radiographs of subjects' heads in whom orthodontic therapy had been started. Analysis of the position of the mandibular M3 and its relation to the bone and other teeth were determined by 4 variables: evaluation of the space for both M3, spatial relation between the second molar and M3, vertical position of the M3 in relation to the alveolar ridge, and inclination of the germ of the M3. RESULTS: In boys, significant correlation was determined on the right side of the jaw, between the retromolar area and the vertical position of M3. Significant correlation was determined in girls, between the retromolar area and the vertical position of M3 on both sides, retromolar area and M3 inclination on the left side, and retromolar area and spatial relation of M3 on the right side. Analysis of correlation between facial growth pattern and 4 variables that determinate the position of M3 showed positive correlation only for the lower right M3 inclination in subjects with anterior facial rotation. CONCLUSION: The present study showed that the amount of retromolar space for the position of the M3 is not a sign of its normal development. No significant differences were determined between the position of M3 and type of facial growth.

A comparison of methods for predicting the size of unerupted permanent canines and premolars.

The aim of this study was to examine the reliability of eight methods for determining the mesio-distal crown diameters (MDD) of the permanent canines and premolars (C, P(1), and P(2)). The study models of 120 children (60 boys and 60 girls) aged from 14 to 18 years treated in orthodontic clinics were measured using Seipel's method, with callipers accurate to 0.01 mm. The correlation coefficients were determined between the MDD of C, P(1), and P(2) measured on the study models and the sums calculated using various other methods. The correlation coefficients derived by comparison with the methods of Moyers, Tanka and Johnston, Droschl et al., Legovic and Hauz, and Berendonk-Nawrath showed a tendency to over-estimate the MDD of C, P(1), and P(2), while the regression methods of Gross and Hasund, Bachmann, and Tränkmann et al. under-estimated the values. Bachmann's method appeared to give the most reliable results.

Regression equations for determining mesiodistal crown diameters of canines and premolars.

In this study, regression equations (prediction equations) were established for the purpose of accurately predicting the widths of the crowns of unerupted canines (C) and premolars (P1 and P2) on the basis of the measured mesiodistal diameter (MDD) and vestibulooral diameter (VOD) of the crowns of the erupted central and lateral incisors (I1, I2) and first permanent molars (M1). On the plaster casts of 120 subjects (60 boys and 60 girls), MDD and VOD of the crowns of I1, I2, C, both P1 and P2, and M1 on both sides in both jaws were measured twice, with a time distance between measurements. Gradual regression equations were derived on the basis of the measurement results, by which the sums of the widths of crowns of C, P1, and P2 can be predicted using three to five predictors. The coefficients of multiple correlations regarding the sex and the jaw varied from 0.79 to 0.85.

Dental and minor physical anomalies in children with developmental disorders--a discriminant analysis.

A discriminant analysis was performed in a sample of 303 children with developmental disorders (DD) and 303 healthy controls (C) in order to test whether some oro-dental and physical minor anomalies could discriminate these groups of children. DD sample comprised 176 mentally retarded (MR) children. 70 children with impaired hearing (IH) and 57 children with impaired vision (IV). The control group included 303 healthy subjects, matched for sex and age. The analysis comprised seven common oral and dental anomalies: median diastema, hypodontia, impacted teeth, microdontia, dens invaginatus, upper lip frenulum and frenulum of the tongue. Minor physical anomalies were assessed by the method proposed by Waldrop et al., as the average number of minor anomalies per individual (W1) and as the weighted score of minor anomalies (W2). Three discriminant functions were obtained by analysis of nine initial variables. Distinct discrimination and considerable distances were found between the centroids of the controls and all groups of DD children. The first two discriminant functions were significant for discrimination between the groups and they explained 98.6% of the total variance. The first function contained 90.2% of information and was defined by the number and weighted scores of minor anomalies. The second variable explained 8.4% of the total variability and was defined by three dental anomalies. The results obtained by the discriminant analysis show that application of dental and minor physical anomalies enables discrimination between the group of healthy children and the groups of children with different developmental disorders.