[Comparison of the effect and safety of Er:YAG laser combined with fluoride and methylene blue-photodynamic therapy on caries prevention].

Objective: To compare the anti-caries effect and safety of Er:YAG laser combined with fluoride and methylene blue-photodynamic therapy (MB-PDT).

Methods: A total of 28 rat dental caries models were established and randomly divided into seven groups: photodynamic therapy (PDT) group, laser combined with fluoride group, laser group, sodium fluoride group, and 0.9% saline control group. Spectrophotometric optical density was used to reflect the growth of Streptococcus mutans. Laser-induced fluorescence diagnostic (LF) instrument was utilized to detect the demineralization degree of dental caries. Histopathological sections were employed to observe the damage of dental pulp and buccal mucosa.

Results: The optical density (OD) value of the PDT and combination groups was significantly lower than that of other treatment groups (P<0.05). An increase in LF value and demineralization occurred in varying degrees with different treatment methods. Histopathological observation showed that pulp and buccal mucosa injury was more obvious in the combination group of 70 mw·cm⁻² and Er:YAG laser group compared with other groups.

Conclusions: Under the same parameters, the combined group and PDT have good germicidal efficacy, but PDT has fewer adverse reactions and less damage. It is an effective and safe method for caries prevention.