External apical root resorption of posterior teeth in asthmatics after orthodontic treatment

External apical root resorption is an undesirable sequela of orthodontic tr eatment, resulting in loss of tooth structure from the root apex, It has be en proposed that systemic factors, such as the inflammatory mediators produ ced in asthma, may enter the periodontal ligament and act synergistically t o enhance root resorption. The aim of this study was to determine if asthma tic patients exhibited a higher incidence or severity of external apical ro ot resorption compared with healthy (no medical conditions) patients after fixed orthodontic treatment. Records were obtained from patients treated wi th fixed appliances; 99 were healthy and 44 had asthma. Using OPGs (panoral films), posterior external apical root resorption was measured on all firs t and second premolars, mesiobuccal and distobuccal roots of the upper firs t molars, and mesial and distal roots of the lower first molars, giving 4 m easurements per quadrant. A 4-grade ordinal scale was used to determine the degree of external apical root resorption. Combined tooth analysis (adjust ed for treatment time, appliance, and extractions) showed that asthmatics h ad significantly more external apical root resorption of posterior teeth af ter treatment compared with the healthy group (P = .0194). Tooth-by-tooth a nalysis (adjusted for treatment time, appliance, extractions, headgear, ove rbite, overjet, sex, and age at start of treatment) found the upper first m olars were most susceptible to external apical root resorption. Although th e incidence of external apical root resorption was elevated in the asthma g roup, both asthmatics and healthy patients exhibited similar amounts of gra de 2 (moderate) and grade 3 (severe) resorption.