Effectiveness of the use of lasers or chlorexidine on the microbial reduction in artificially caries lesions

Abstract

In order to preserve the dental structure, dentin remnants affected by caries may be left after removal of carious tissue. The use of disinfectant solutions is an alternative to reduce or eliminate bacteria after cavity preparation. In addition, caries removal methods, less invasive than the traditional use of drills, have been developed, such as high-power lasers. In the context of microbial reduction, both high power lasers (photothermal effect) and low power lasers associated with photosensitizers (antimicrobial photodynamic therapy) can be used. The objective of this in vitro study is to evaluate the use of lasers or chlorhexidine inmicrobial reduction in artificially developed caries lesions. Sixty human dentin discs will be analyzed according to surface treatment (n=10): G1 - no treatment; G2 - 2% chlorhexidine digluconate; G3 - high power Er: YAG laser 80 mJ, 2 Hz; G4 - high power Er:YAG laser 60 mJ, 4 Hz; G5 - antimicrobial photodynamic therapy 1 (660 nm low power laser + 0.01% methylene blue); G6 - antimicrobial photodynamic therapy 2 (660 nm low power laser +0.005% methylene blue). Affected dentin caries will be induced by an artificial model developed with S. mutans (caries lesions of 500 µm in depth). Carious dentin will becollected by a sterile carbide spherical bur, positioned at the greatest depth of the lesion (500 µm). The primary outcome (quantitative evaluation) will be the reduction of bacteria,performed by counting colony-forming units (CFU) followed by statistical analysis comparing the bacterial reduction in each of the proposed treatments. (AU)