Argon laser irradiation and acidulated phosphate fluoride treatment in caries-like lesion formation in enamel: an in vitro study.

The purpose of this in vitro study was to determine the combined effects of argon laser irradiation (ArI) and acidulated phosphate fluoride treatment (APF) on caries-like lesion formation in human enamel. Each specimen was divided into tooth quarters with each quarter assigned to one of four groups: 1) control; 2) ArI Only; 3) ArI before APF treatment; 4) APF treatment before ArI. After a fluoride-free prophylaxis, acid-resistant varnish was applied to the tooth quarters, leaving sound enamel windows exposed on buccal and lingual surfaces. Argon laser irradiation was at 2 watts for 10s (100J/cm2). APF treatment was with a 1.23% APF gel for 4 min. Lesions were created in sound enamel windows with an acidified gel. After lesion formation, sections were obtained and imbibed with water for polarized light study. Body of the lesion depths were determined and compared among the four groups. Lesion depths were: 195 +/- 23 microns for control; 129 +/- 17 microns for ArI only; 96 +/- 14 microns for ArI before APF; and 88 +/- 11 microns for APF before ArI. Significant differences (P < 0.05) were found between the control group and all treatment groups, and between the ArI only group and both combined APF and ArI groups. Significant difference (P > 0.05) was not found between the ArI before APF and the APF before ArI groups. Laser irradiation alone reduced lesion depth by 34% compared with control lesions. When ArI was combined with APF treatment, lesion depth decreased by more than 50% compared with control lesions, and by 26 to 32% when compared with lased-only lesions.(ABSTRACT TRUNCATED AT 250 WORDS)