Comparison between the protective effect of applying sodium fluoride varnish alone and applying CO2 laser with it in permanent teeth.  In Vitro study

Background Fluoride administration plays a critical role in the management and prophylaxis of dental caries. Research indicates that laser irradiation can enhance the uptake of fluoride into dental enamel, an effect that is particularly pronounced when used as an adjunct to topical fluoride treatments. The present study aimed to evaluate the impact of CO₂ laser irradiation on fluoride uptake in the enamel of permanent teeth. Methods Six human upper premolars, extracted for orthodontic reasons, were selected for this study. The roots were separated from the crowns, and each crown was then sectioned mesiodistally to create mesial and distal halves. These halves were randomly assigned to either an experimental or a control group (n = 6 per group). All specimens received an application of 5% sodium fluoride (NaF) varnish. Subsequently, the samples in the experimental group were subjected to irradiation with a 1 W CO2 laser for a duration of 15 seconds. To assess the effects of the treatments, fluoride uptake was measured and the topographic characteristics of the enamel surface were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Statistical analysis of the data was performed using SPSS software version 26 (IBM, USA). Results Energy-dispersive X-ray spectrometry analysis showed a significant increase in the percentage of fluoride with the application of the laser, The results of the mean ranks showed that the fluoride and CO₂ laser group recorded significantly higher ranks in the fluoride element (8.75 vs. 4.25), reflecting a higher concentration and confirmed statistical significance. Statistically, in the Mann-Whitney U test, a significant statistical difference in fluoride ratios appeared between the two groups (P value = 0.026) smaller than (0.05), which indicates the effectiveness of using CO₂ lasers in enhancing fluoride absorption within the tooth structure. Conclusion The results showed CO₂ laser irradiation of dental enamel resulted in increased fluoride uptake.