Root resorption after orthodontic treatment in high- and low-risk patients: analysis of allergy as a possible predisposing factor.

The development of excessive root resorption during orthodontic tooth movement is an adverse side-effect, which is of great concern. The aim of this investigation was to analyse factors that might be associated with orthodontically induced root resorption. After buccal movement of maxillary premolars in 96 adolescents, the experimental teeth were extracted and subjected to histological analysis and measurement of resorbed root area. Fifty individuals, 18 boys and 32 girls, mean age 13.4 years, were selected and divided into two equal groups: the high-risk group based on measurements of the most severe root resorptions, and the low-risk group on measurements of mild or no root resorptions. After a preliminary screening of possible risk factors regarding root resorption, i.e. root morphology, gingivitis, allergy, nail-biting, medication, etc., only those subjects with allergy showed an increased risk of root resorption, but this was not statistically significant.