Structural changes in dental enamel induced by high energy continuous wave carbon dioxide laser

The morphological changes in dental enamel exposed to a high energy continuous beam surgical carbon dioxide laser were studied with a wet-scanning electron microscope. Utilizing a 1 mm focused beam, energy levels of 5, 10, and 12.5 watts were applied to the external enamel surface of teeth for between 0.05 and 2 seconds. Subsequent examination showed melting and resolidification of the surface enamel. Examination in cross section revealed three different zones of change, which were consistent in thickness. The outer layer of melted and resolidified enamel approximates 100 microns in width, whereas the next zone of acid resistant amorphous enamel measures only 12 microns in width and the third zone of porous enamel measures approximately 110 microns in width. Though of no immediate practical value in dentistry, the exact physical chemical changes occurring in the enamel warrant further investigation.