A scanning electron microscopic study of early enamel caries formed in vivo beneath orthodontic bands

A clinical trial was conducted to investigate the development of caries lesions associated with fixed orthodontic appliance therapy. To introduce a cariogenic challenge on sound buccal enamel surfaces in vivo, specially designed orthodontic bands were attached to premolars scheduled for extraction for orthodontic reasons. The bands were modified by having two metal wires (0.8 mm in diameter) welded to the inner surface of the band to produce a space for plaque accumulation similar to that occurring under loose orthodontic bands. The bands were cemented with a zinc phosphate cement (Tenet) and left in situ for 4 weeks. Of 22 premolar teeth banded in eight different patients, eight showed definite white spot lesions, eight showed definite faint enamel opacities, and six showed no discernible lesions. Examination of definite white spot lesions by scanning electron microscopy revealed characteristic patterns of initial tissue destruction. Focal holes and an accentuation of the perikymata were observed affecting the enamel surface zone, an area previously considered to remain relatively intact during the development of a caries lesion. The superficial nature of the caries lesions observed and the rapidity of their formation is significant in the clinical management of decalcified areas forming beneath orthodontic bands.