Caries inhibition in vital teeth using 9.6- m CO

The aim of this study was to test the hypothesis that in a short-term clinical pilot trial short-pulsed 9.6 m CO -laser irradiation significantly inhibits demineralization . Twenty-four subjects scheduled for extraction of bicuspids for orthodontic reasons (age 14.9 ± 2.2 years) were recruited. Orthodontic brackets were placed on bicuspids (Transbond XT, 3M). An area next to the bracket was irradiated with a CO -laser (Pulse System Inc, Los Alamos, New Mexico), wavelength 9.6 m, pulse duration 20 s, pulse repetition rate 20 Hz, beam diameter 1100 m, average fluence 4.1 ± 0.3J/cm , 20 laser pulses per spot. An adjacent nonirradiated area served as control. Bicuspids were extracted after four and twelve weeks, respectively, for a quantitative assessment of demineralization by cross-sectional microhardness testing. For the 4-week arm the mean relative mineral loss Z (vol% × m) for the laser treated enamel was 402 ± 85 (mean ± SE), while the control showed significantly higher mineral loss ( Z 738 ± 131; P = 0.04, t-test). The difference was even larger after twelve weeks (laser arm Z 135 ± 98; control 1067 ± 254; P = 0.002). The laser treatment produced 46% demineralization inhibition for the 4-week and a marked 87% inhibition for the 12-week arm. This study shows, for the first time , that the short-pulsed 9.6 m CO -laser irradiation successfully inhibits demineralization of tooth enamel in humans.