Area Measurement of Orthodontic White Spot Lesions Over 26 Weeks

Objectives: An observational prospective longitudinal study to measure the changes in area of post-orthodontic white spot enamel lesions for 26 weeks after removal of fixed appliances. Methods: The sample group consisted of 9 orthodontic patients who had 25 teeth presenting with white spot lesions. Image acquisition was at monthly intervals with a digital camera system, using polarized light and calibration under standardized conditions. Subjects maintained their usual toothbrushing regime after debond. No additional fluoride preparations were used other than conventional toothpaste. Images were processed using image processing software. The white lesion was outlined by hand. Intra-operator error assessment was performed for repeated measurements. Repeatability error showed that for random error the Intra Class Correlation Coefficient (ICC) ranged from 0.97 to 0.99. Paired samples t-tests showed no systematic error (p< 0.05). Results: There was a reduction in size of white lesions with time. Using lesion size as the outcome measure the mean size of the lesions at debond was 2.72 sq.mm (SD 1.72). After 26 weeks the mean size was 1.03 sq.mm (SD 0.84) Using an unpaired t-test this change was significantly different (p= 0.037). In most cases rapid size reduction occurred during the first 12 weeks after appliance removal. In 4 cases studied for more than 26 weeks little further reduction occurred. Conclusions: There was a reduction in area of post-orthodontic white spot lesions with time probably due to remineralization. The most rapid reduction occurred during the first 12 weeks after appliance removal. Lesion size reduced on average by a third after 12 weeks and a half after 26 weeks.