In vitro acid resistance of CO2 and Nd-YAG laser-treated human tooth enamel.
The purposes of this study were to test the effectiveness of laser treatment (pulsed CO(2) and pulsed Nd-YAG) on in vitro acid resistance of human enamel. Thirty enamel surfaces were prepared from 10 extracted permanent premolars (3 surfaces per tooth). Two experimental surfaces on each tooth were irradiated with either CO(2) or Nd-YAG lasers. All specimens were demineralized in 10 ml lactate buffer for 24 or 72 h after laser treatment. After 24-hour acid treatment the mean concentration of calcium that dissolved into the lactate buffer in the CO(2) laser group was significantly less than in the control group, while the dissolved calcium concentration in the Nd-YAG laser group did not differ from the control group (p > 0.05). The erosion depth in the CO(2) laser group was significantly shallower than in the Nd-YAG laser group (p < 0.001). After 72-hour acid treatment, the acid resistances of neither group of laser-treated surfaces differed significantly from the controls. By scanning electron microscopy, the acid-eroded laser-treated enamel surfaces had type I and type II etching patterns, fissures, and disordered rough surfaces compared to control enamel, with a regular type II etching pattern. CO(2) laser-treated tooth enamel was more resistant to acid challenge than was Nd-YAG laser-treated enamel, given the same fluence, but neither type of laser increased acid resistance of subsurface enamel.
Tsai
Chia-Ling
CL
Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
Lin
Yng-Tzer
YT
Huang
Shun-Te
ST
Chang
Hseuh-Wen
HW
D000143:Acids / Q000009:adverse effects; D000704:Analysis of Variance; D002118:Calcium / Q000032:analysis; D002245:Carbon Dioxide; D003743:Dental Enamel / Q000187:drug effects / Q000528:radiation effects*; D003747:Dental Enamel Solubility / Q000187:drug effects / Q000528:radiation effects*; D006358:Hot Temperature; D006801:Humans; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D008859:Microscopy, Polarization; D009354:Neodymium; D018709:Statistics, Nonparametric; D013499:Surface Properties / Q000187:drug effects / Q000528:radiation effects; D017001:Tooth Demineralization / Q000139:chemically induced; D014077:Tooth Erosion / Q000139:chemically induced / Q000517:prevention & control*
D000143:Acids; D002245:Carbon Dioxide; D009354:Neodymium; D002118:Calcium