Bond strength to simulated hypersensitive dentin treated with irradiation by Nd:YAG laser, glutaraldehyde-based desensitizing or the association of both

• Grant number: 16/25468-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2017
• End date: February 28, 2018
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Luciana Fávaro Francisconi dos Rios
• Grantee: Lucas Monteiro Pereira
• Host Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

It has been previously found that irradiation by Nd:YAG laser, as a pretreatment, favors immediate and longitudinal bond strength (BS) to simulated hypersensitive dentin and that such effect is independent of the persistence, or not, of the etiological factor. It is unknown, however, if the same would apply to the treatment with a glutaraldehyde-based desensitizer, alone or in combination with the irradiation, the latter situation being the unique in that there is no pain reported, rather than reduction, under tactile and evaporative stimulus, after six months. Immediate and medium-term BS of a self-etch adhesive plus a composite to simulated hypersensitive dentin treated with irradiation by Nd:YAG laser, with a glutaraldehyde-based desensitizer or the combination of both will be, thus, evaluated. Superficial occlusal dentin of third molars (n=28) will be submitted to a 600-grit SiC paper (1 min) and to an acidic challenge with citric acid (6%; 1 min; simulated hypersensitive dentin: open tubules), and, afterward, it will be irradiated by the Nd:YAG laser (L, n=7; 1.0 W, 10 Hz, 100 mJ, 4 irradiations of 50-60 s each), submitted to the application of a glutaraldehyde-based desensitizer (G, n=7), irradiated and submitted to the application of the desensitizer (LG, n=7), or untreated (C/control, n=7). Composite buildups will be constructed with Filtek Z350 following the application of the adhesive system ClearfilTM SE Bond®. After 24 h (distilled water/37ÚC), specimens will be sectioned in beams, which will be tested (¼TBS; 0.5 mm/min) immediately or after 6 months aging. An extra tooth for each group will be treated just like the others, but the fluorescent dye rhodamine B will be previously added (0.02 mg/mL) to the adhesive systems to allow a qualitative evaluation of the adhesive interface by means of Laser Scanning Confocal Microscopy. If obtained BS data are considered normal and homogeneous, a two-way ANOVA and a subsequent analysis of multiple comparisons, if necessary, will be applied, with a significance level of 5%. (AU)