Clinical and scanning electron microscopic study of surface changes of incipient caries lesions after debonding

The surface features of incipient caries lesions around bonded orthodontic brackets were assessed longitudinally. In standardized periods after debonding and clean-up, color slides were made and silicone impressions were taken of two maxillary incisors on each of six adolescent patients. These teeth were characterized by varying degrees of macroscopically visible demineralized white areas around the bonded brackets. The color slides were studied in a dark room. The positive surface replicas were studied in SEM. At the time of debonding heavy accumulations of dental plaque were observed in all areas corresponding to the white, demineralized areas. During the experimental period there was a reduction in these plaque deposits. The appearance of the lesions changed from chalky-white at the time of debonding to a more diffuse opacity, particularly in the peripheral parts of the lesion. Examination of the surface replicas in the SEM revealed a general tendency toward leveling of the surface of the lesion indicating a loss of porous tissue. At higher magnification the lesions showed signs of wear. Four teeth were presented to illustrate typical examples of the time-related changes at the surface. The present study confirmed that removal of cariogenic challenge results in arrest of further demineralization. The gradual regression of the lesion at the clinical level was believed to be primarily a result of surface abrasion with some redeposition of minerals.