Classification of occlusion reconsidered

Prevalence of and factors affecting malocclusion in primary dentition among children in Xi'an, China

BACKGROUND

This study aimed to investigate the prevalence and associated factors of malocclusion among children with primary dentition in Xi'an, China.

METHODS

A total of 2,974 subjects were selected from local schools in Xi'an city using a stratified cluster sampling method from January to September 2015. After screening samples according to the inclusion criteria, the final sample size comprised 2,235 pre-school children, with a mean age of 4.82 (SD, 1.76; range, 2.63-6.12) years. Malocclusion traits were assessed by trained clinicians followed by the evaluation of associated factors through clinical examination and a precisely designed questionnaire including data regarding gender, birth place, parental education level, monthly familial income, parental attitude toward the problem of malocclusion, feeding methods of the children, feeding postures, pacifier use, and delivery methods. Data were analyzed using the Chi-square test and logistic regression analysis.

RESULTS

The most common type of malocclusion was increased overjet (34.99 %) in the sagittal direction, deep overbite (37.58 %), and midline deviation (25.32 %) in the vertical and transverse directions, respectively. The prevalence of posterior crossbite, anterior crossbite, and anterior open bite was 7.56, 6.80 and 6.98 %, respectively. The prevalence of the anterior edge-to-edge occlusion was the lowest (2.46 %). The variables associated with malocclusion (P < 0.05) were birth place (odds ratio [OR] = 1.741 with 95 % CI of 1.384-2.162), insufficient abrasion of primary canines (OR = 1.465; 95 % CI of 1.153-1.894), caries in primary teeth (OR = 2.045; 95 % CI of 1.665-2.539), tongue thrusting (OR = 2.833; 95 % CI of 1.640-3.649), mandibular prognathism (OR = 2.621; 95 % CI of 1.574-3.689), and finger sucking (OR = 1.573 with 95 % CI of 1.098-2.014). The feeding methods (OR = 3.614 with 95 % CI of 3.087-4.596) along with the method of delivery (OR = 1.847 with 95 % CI of 1.323-2.451) have been observed to play an important role in the morbidity of malocclusion (P < 0.05).

CONCLUSIONS

The prevalence of malocclusion among pre-school children in Xi'an is higher compared to that in other geographical parts of China. Therefore, early attention to the development of occlusion and necessary interventions toward the associated factors are important to reduce its prevalence and further adverse effects.

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

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.

Condition-specific impacts on quality of life attributed to malocclusion by adolescents with normal occlusion and Class I, II and III malocclusion

OBJECTIVE

To compare the prevalence, intensity, and extent of condition-specific oral impacts on quality of life attributed to malocclusion by Brazilian adolescents with normal occlusion and those with Angle Class I, II, and III malocclusion.

MATERIALS AND METHODS

Four groups of 55 adolescents were configured such that each group represented normal occlusion, as well as Angle Class I, II, and III malocclusion. No radiographs were taken. Adolescents aged 15 to 16 years were selected from those attending all secondary schools in Bauru (Sao Paulo, Brazil). The Oral Impacts on Daily Performances index was used to collect data on condition-specific impacts (CSIs) attributed to malocclusion. The prevalence, as well as the intensity and extent, of CSIs was compared among the four groups with the use of Chi-square and Kruskal-Wallis tests, respectively.

RESULTS

Groups were comparable according to sex, age, and socioeconomic status. The prevalence of CSI was significantly different between groups (P = .039). Class II and III malocclusion groups reported a higher prevalence of CSI than those with normal occlusion and Class I malocclusion. However, the intensity and extent of CSI were not significantly different between groups.

CONCLUSIONS

The prevalence, but not the intensity and extent, of CSIs attributed to malocclusion differed among groups with different malocclusions. The present findings support the concept that malocclusion has physical, psychological, and social effects on quality of life.