The Impact of CO۲ Laser Treatment and Acidulated Phosphate Fluoride on Enamel Demineralization and Biofilm Formation

Abstract Introduction: This study evaluated the impact of CO۲ laser treatment and acidulated phosphate fluoride (APF) on enamel demineralization and biofilm formation, using in vitro and in situ designs.Methods: Demineralized enamel slabs were distributed among ۸ groups: placebo, placebo + continuous CO۲ laser, placebo + repeated CO۲ laser, placebo + ultrapulsed CO۲ laser, ۱.۲۳% APF, APF + continuous CO۲ laser, APF + repeated CO۲ laser and APF + ultrapulsed CO۲ laser. In the in vitro study, ۱۵ enamel slabs from each group were subjected to a pH-cycling regimen for ۱۴ days. In the cross over in situ design, ۱۱ volunteers wore palatal appliances with demineralized enamel slabs for ۲ periods of ۱۴ days each. Drops of sucrose solution were dripped onto enamel slabs ۸×/day. Biofilms formed on slabs were collected and the colony-forming units (CFU) of Streptococcus mutans and Lactobacillus were determined. Results: For both in vitro and in situ studies, there was no significant difference between treatments (P > ۰.۰۵). However, all treatments increased microhardness of demineralized enamel (P < ۰.۰۵). After a further in situ cariogenic challenge, with the exception of the placebo, all treatments maintained microhardness values (P < ۰.۰۵). Microbiological analysis showed no difference in Streptococcus mutans (P > ۰.۰۵) or Lactobacillus (P > ۰.۰۵) counts between groups. Conclusion: The results suggest that APF gel combined with the CO۲ laser, regardless of the pulse emission mode used, was effective in controlling enamel demineralization, but none of the tested treatments was able to prevent bacterial colonization. Keywords: Dental caries Enamel Fluoride Laser Microbiology