Argon laser irradiation and fluoride treatment effects on caries-like enamel lesion formation in primary teeth: an in vitro study

To evaluate topical acidulated phosphate fluoride (APF) and low fluence argon laser (Ar) treatment effects on in vitro caries formation in primary tooth enamel.

20 extracted or exfoliated primary teeth with sound buccal and lingual surfaces underwent soft tissue debridement and a fluoride-free prophylaxis. Treatment groups were: (1) Control [n=5]; (2) Ar [231mW, 10 seconds, 11.5J/cm2; n=5], (3) 1.23% APF for 4 minutes before Ar [n=5]; (4) Ar before APF [n=5]. Buccal and lingual enamel surfaces were treated, and then rinsed in deionized,distilled water (24 hours). An acid-resistant coating was applied leaving buccal and lingual sound enamel windows exposed. In vitro enamel caries was created (2.2 mM calcium, 2.2 mM phosphate, 5.0 mM fluoride, pH 3.90, 10 days). Following longitudinal sectioning, two lesions per primary tooth (10 lesions total) with each group were evaluated for lesion depth (polarized light, water imbibition) and compared (ANOVA, Duncan's Multiple Range).

Argon laser irradiation alone provided a 41% reduction in lesion depth (176 +/- 21 microm, P< 0.05) when compared with that for the no treatment controls (297 +/- 31 microm). The combination of argon laser irradiation with APF treatment resulted in lesion depth decreases of slightly over 50% (140 +/- 23 microm for APF before ArTx; 124 +/- 17 microm for ArTx before APF, P< 0.05) compared with control lesion depths, and 20 to 30% over that for argon laser treatment alone (P< 0.05). There was no statistical difference in lesion depth regardless of whether fluoride treatment occurred before or after laser irradiation (P> 0.05).