In vitro controlled elemental analysis to evaluate the combined effect of acidulated phosphate fluoride with Er:YAG and diode lasers

Acidulated phosphate fluoride (APF) application is used for dental caries prevention. Combining APF with different laser wavelengths increases acid resistance in enamel. To assess the effects of Er:YAG (2940 nm) laser and diode (940 nm) laser after the application of APF on morphology and mineral content of enamel surfaces of human teeth in vitro. Twenty (20) freshly extracted third molar crowns were collected and split longitudinally into halves. Ten (10) halves were given to each of the following groups: group 1 (control), group 2 (application of 1.23% APF gel only), group 3 (diode laser; 1 W for 60 sec, contact mode after APF gel), and group 4 (Er:YAG; 80 mJ, 0.8 W, 10 Hz; in pulsed mode for 10 sec after APF gel). Specimens were morphologically examined by scanning electron microscope (SEM), and mineral content was analysed by energy dispersive X-ray (EDX). Collected data were statistically analysed by ANOVA. Morphologic results were superior in group 3 followed by group 2 and group 1 with the least change in group 4. EDX of calcium (Ca), phosphorous (P), and Ca/P ratio weight % showed the highest value with no statistical significance between groups 2 and 1, and higher with statistical significance in groups 3 and 4 in descending order. Carbon weight % showed highest results in group 4 then 3, 2, and 1. Fluoride weight % showed highest statistical results in group 4 then 2, 3, and 1. The diode laser showed superior morphological results after APF application compared to the Er:YAG laser. The Er:YAG increased fluoride absorption on outer enamel surfaces.