Efficacy of the use of lasers or chlorhexidine in microbial reduction in artificially produced caries lesions

Author(s)

Fernanda Cristina Nogueira Rodrigues

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia (FO/SDO)
• Defense date: 2018-11-26

Examining board members

Patricia Moreira de Freitas Costa e Silva; Andréa Dias Neves Lago; Karen Müller Ramalho; Maria Regina Lorenzetti Simionato

• Advisor: Patricia Moreira de Freitas Costa e Silva

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 (photothermal effect) and low power lasers combined with photosensitizers (antimicrobial photodynamic therapy) can be used. The objective of this in vitro study was to evaluate the use of lasers or chlorhexidine in microbial reduction in artificially developed caries lesions. Sixty human dentin discs were analyzed according to surface treatment (n = 10): G1 - no treatment; G2 - 2% chlorhexidine digluconate; G3 - high power Er:YAG Laser (2.94 ?m); G4 - high power Er,Cr:YSGG Laser (2.78 ?m); G5 - aPDT 1 (low power laser 660 nm + 0.01% methylene blue); G6 - aPDT 2 (low power laser 660 nm + 0.005% methylene blue). Caries affected dentin was induced by an artificial model developed with S. mutans, with lesion depth of approximately 260 ?m. The carious dentin was collected using a sterile Carbide spherical drill before and after the proposed treatments. For standardization of the collection, the insertion of the entire diameter of the active tip into the dentin tissue was performed (0.5 mm). The primary outcome was the bacterial reduction, considering the colony forming units (CFU). To compare the performance of the treatments, the Kruskal Wallis test, complemented by the dms test, was used to identify the significant differences, considering a significance level of 5%. According to the results, there was a microbial reduction for all the experimental groups evaluated, but with no significant statistical difference among them (p = 0.1133). Thus, all proposed treatments were effective for microbial reduction. (AU)

• FAPESP's process: 17/13451-1 - Effectiveness of the use of lasers or chlorexidine on the microbial reduction in artificially caries lesions
• Grantee: Fernanda Cristina Nogueira Rodrigues
• Support Opportunities: Scholarships in Brazil - Master