Malocclusion and occlusal traits in an urban Iranian population. An epidemiological study of 11- to 14-year-old children

Abstract

The aim of this cross-sectional study was to determine the prevalence of malocclusions, occlusal traits, and their gender distribution in urban Iranian school children. Five hundred and two subjects (253 females and 249 males, aged 11-14 years) were examined. Molar relationship, overjet (OJ), overbite, midline deviation, crossbite, and crowding/spacing were recorded. Gender dimorphism was evaluated by the chi-square test. According to the classification of Angle, the prevalence of Class I, Class II division 1, Class II division 2, and Class III malocclusions was 41.8, 24.1, 3.4, and 7.8 per cent, respectively. Symmetric molar relationship was present in 69.5 per cent. An OJ of at least 3.5 mm or more was present in 28.1 per cent; an OJ of more than 6 mm in 3.6 per cent, and 4.2 per cent had a reverse OJ. A normal overbite was observed in 60.4 per cent, while 34.5 per cent had an increased and 2.2 per cent a very deep overbite. An anterior open bite (AOB) was present in 1.6 per cent and a scissor bite or anterior crossbite in 2 and 8.4 per cent, respectively. A posterior crossbite was observed in 12.4 per cent (8.4 per cent unilateral, 2 per cent bilateral, and 2 per cent in association with an anterior crossbite). Midline deviation was present in 23.7 per cent. Severe crowding (>or=5.1 mm) was observed in 16.7 and 10.8 per cent and spacing in 18.9 and 20.7 per cent of the maxillary and mandibular arches, respectively. Significant gender differences were found for overbite (P < 0.001), midline deviation (P < 0.05), and maxillary and mandibular arch crowding/spacing (P < 0.05). The prevalence of Class II malocclusions was comparable with Caucasians; however, the most severe forms of Class II malocclusions were rare in this Iranian population. The relative prevalence of Class III malocclusions in the present study was greater than in Caucasians. Crowding was the most common dental anomaly in both arches.

Distribution of sagittal occlusal relationships in different stages of dentition

“…The prevalence of Class II malocclusion showed a significant increasing trend towards the late mixed dentition stage, and then slightly decreased in the permanent dentition stage. This finding is consistent with the results of Thilander et al 5 showing that Turkish subjects have a lower frequency of Class II malocclusions than Iranian, 16 Finnish, 15 Danish, 14 and Asian subjects. 3 Class III malocclusion was observed to be the least frequent malocclusion type in the deciduous dentition stage, and the prevalence increased towards the permanent dentition stage.…”

“…The mean prevalence of Class III malocclusion (11.7%) in our study of the Turkish population was higher than in Danish, 14 Finnish, 15 Iranian, 16 Tanzanian, 21 German, 22 and Swedish 23 populations but lower than in a Chinese population (49.1%). 8 The high prevalence of Class III malocclusion in Chinese might be due to differences in ethnicity.…”

“…16,21,25,26 Contrary to the present results, Wood 27 found a higher rate of Class I malocclusion in female subjects than in male subjects, and Onyeaso et al 24 reported higher rates of Class II and III malocclusion in male subjects than in female subjects.…”

“…4,5,6,8,13,14,15 In this study, the sample set reflects the greater Turkish population because Ankara is the capital city located in the central part of Turkey, where individuals from every province of Turkey come to receive health care. Although several studies have classified malocclusions by chronological age, 13,16 malocclusions appear to be more influenced by development of dentition than by chronological age. Permanent teeth have been found to emerge into the oral cavity earlier in African and AfricanAmerican children than in Caucasians.…”

“…2,3,4,5,6,7,8,13,14,15,16,18,19,21,24 It is notable that prevalence rates varied even within Turkish populations of the same origin. Differences between our results and those of other studies are most likely due to differences in the selection of subjects.…”