The Relationship between Caries and Malocclusion in Migrant Children in China

Purpose: A retrospective, cross-sectional study to evaluate the relationship between caries and malocclusion in the early and the late mixed dentitions in Chinese children. Methods: Charts from 646 subjects between the ages of 6 and 13 with minimal or no prior dental treatment and no prior orthodontic treatment were obtained. The subjects were ethnic Chinese and were migrants from all over China living in the Shanghai metropolitan area. The sample was divided into four groups based on sex and dental age; two groups, “caries-free” and “caries” based on the DMFT score; and four groups: those with interproximal tooth structure lost due to caries (ITSLC) in the upper arch only, those with ITSLC in the lower arch only, those with ITSLC in both arches, and those with no ITSLC. Statistical comparisons were performed. Results: No difference was found in the DMFT score or the rate of ITSLC between the four groups. Overjet was greater in late mixed dentition males than in early mixed dentition females. Upper midline diastema was larger in the early mixed dentition than the late mixed dentition. Crowding in the upper arch was less in the early mixed dentition than the late mixed dentition. In the early mixed dentition, overbite was more likely to be ideal in subjects with DMFT>0, upper crowding improved in subjects with ITSLC in the upper arch and in both arches, and the rate of anterior crossbite increased in subjects with ITSLC in the upper arch. In the late mixed dentition, crowding in the upper and lower arch increased in subjects with DMFT>0, upper crowding improved in subjects with ITSLC in the upper arch and in both arches, and the rate of anterior crossbite increased in subjects with ITSLC in the upper arch. In the total sample, crowding in the lower arch only increased in subjects with DMFT>0, overjet improved in subjects with ITSLC in the upper arch, and lower crowding increased in subjects with ITSLC in both arches. Conclusion: According to this study, a relationship exists between caries and malocclusion, and between ITSLC and malocclusion, and some relationships change with dental age.