Prevalence of malocclusions in a sample of 4-5-year-old Bulgarian children

Table 5. Percentage prevalence of malocclusions in primary dentition.

Posterior cross bite

Unilateral- 15 Bilateral- 7

3.2 % 1.5 %

4. Discussion The overall prevalence of malocclusions is high- 64.4 %. According to the scientific literature, the prevalence of malocclusions in primary dentition varies from 22 % to 93 % 9, 10 due to racial characteristics and different occlusion recording methods. We found a higher prevalence of malocclusions as compared to some previous studies conducted on the Bulgarian population by Nikolov & Atanasov, 11 who found 44.5 % prevalence. The difference in prevalence is probably due to the fact that at that time a mass orthodontic prevention program was held. The generalized spacing in this sample is 78.2 % and it is corresponding to the findings of Foster & Hamilton 8 with 70 %. The prevalence of no spacing and crowding concurs with other studies, 4, 12, 13 but it is much lower than the results for the British children. 8 Our results for the prevalence of several concurrent malocclusions in primary dentition are in agreement with other studies. 14 The canine sagittal relationships showed that 60 % of the children have Class I, 30 % have Class II and 10 % have Class III and the results are corresponding to the findings for the European

4, 10, 15

population. Our study conducted on the Bulgarian population showed a percentage distribution of a flush terminal molar relation in 70.1 % of the subjects on the right side and 72.4 % on the left, which is similar to studies done by Nanda et al. 16 A mesial step and a distal step in this sample are equally distributed in 14.4 % and 14.5 %, respectively. Our results for the mesial step are in agreement with the findings of Baume 17 and Ravn, 18 but in disagreement with the results of Johannsdottir et al., 19 who found that 60 % of their sample had mesial step occlusal relationships in primary dentition. Our results for the distal step are similar to the findings by Grabowski et al., 10 who found 15.5 %“ distalization” in primary dentition. The normal overjet is in agreement with the results by Berneburg et al., 14 but the increased overjet was assessed in 9.5 % of this sample, which is lower than their findings. Our results for the decreased overjet are higher than other studies 10, 14 but similar to the findings of Müssig. 15 An anterior crossbite was observed in 6.4 % of the sample, which resembles a study conducted by Kerouso 20 for the Finnish children. The prevalence of a normal overbite is 30.1 %. We also found 27.2 % of an anterior edge-to-edge bite and, at the age of 5, it is a norm according to Hotz. 21 The findings are in agreement with the results by Nanda et al., 16 Müssig 15 and Berneburg et al. 14 But on the other hand, the high frequency may be due to the self-correction of an anterior open bite after interrupting the action of external factors. 22 In this sample, a moderate anterior open bite(< 3mm) and a severe anterior open bite(> 3mm) were registered respectively in 6.8 % and 0.4 % of the children, which is in agreement with Berneburg et al., 14 who found 4.6 % prevalence of an anterior open bite. The prevalence of an anterior open bite in this sample is significantly less than the findings of Müssig 15 and Tschill et al. 4 Our results showed prevalence of a deep bite and a deep bite with gingival contact, 27 % and 8.5 %, respectively, which is similar to the studies done by Müssig 15 and Grabowski et al. 10 In this sample, boys have more severe deep bites and there is also a statistically significant increase in prevalence of a deep bite with gingival contact with the increasing of the age, which concurs with other studies’ results, 10, 22 but it is in disagreement with the results of Berneburg et al. 14 A posterior cross-bite was seen in 4.7 % and a posterior edge-to-edge bite in 1.9 % of all the children in this study. Other investigators report that a deciduous

8, 10, 18 posterior cross bite ranges between 7-12 %. But our findings are similar to Hensel( 12) and Stahl & Grabowski, 6 who report 5.1 % and 4 % respectively. Available literature suggests that the development of the occlusion and oral functions in primary dentition is a continuum for the further

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