Evaluation of Super Short Pulse Er:YAG laser treatment on adhesion of sound and caries affected dentin: longitudinal study

Author(s)

Cynthia Soares de Azevedo

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia (FO/SDO)
• Defense date: 2015-12-11

Examining board members

Adriana Bona Matos; Camillo Anauate Netto; Sergio Eduardo de Paiva Gonçalves; Patricia Moreira de Freitas Costa e Silva; Luciana Kfouri Siriani

• Advisor: Adriana Bona Matos

Abstract

This longitudinal study investigated the influence of super short pulse Er:YAG laser treatment on microshear bond strength (?SBS), adhesive and hybrid layer nanohardness test and qualitative interface scanning electron microscopy (SEM) of two self-etch adhesive systems to sound (SD) and caries-affected like dentin (CAD). Additionally, qualitative investigation of surface treatments by SEM and transmission electron microscopy (TEM) were performed. CAD lesions (4x5mm) were produced by 7 days S. mutans biofilm cariogenic challenge in 215 human ground flat human dentin specimens, enabling paired data by substrate. Specimen were divided in groups according to surface treatment [control-no treatment-(G1); Laser 80-80mJ, 2Hz, 12.58J/cm2-(G2); Laser 50-50mJ, 10Hz, 9.4J/cm2-(G3)]; self-etching adhesive system [Clearfil SE Bond(CF) and Single Bond Universal(SB)]; substrate [SD(h) or CAD(a)] and artificial saliva storage [24 hours(24) or 1 year(1)]: CFG1h24; CFG1h1; CFG1a24; CFG1a1; CFG2h24; CFG2h1; CFG2a24; CFG2a1; CFG3h24; CFG3h1; CFG3a24; CFG3a1; SBG1h24; SBG1h1; SBG1a24; SBG1a1; SBG2h24; SBG2h1; SBG2a24; SBG2a1; SBG3h24; SBG3h1; SBG3a24; SBG3a1. Pulse duration was set in 50?s for laser groups. ?SBS, nanohardness and interface SEM specimen preparation was constructed with Z350XT composite resin. Adhesive systems were applied according to manufacturer\'s instructions. Surface SEM and TEM specimen only evaluated treatment effects on distinct substrates. The ?SBS and nanohardness means were analysed using three-way ANOVA and Tukey´s multiples comparisons test (?=0.05). For ?SBS test, for both adhesive systems, and all surface treatments, CAD revealed lower ?SBS values compared to SD; the influence of artificial saliva storage was substrate dependent. CAD specimens resulted in lower ?SBS values after 1 year, while no difference among experimental groups was observed in SD. The adhesive layer (AL) nanohardness statistical evaluation revealed that only CF specimens decreased the AL nanohardness after 1 year of storage. The hybrid layer (HL) produced with CF and SB, resulted in lower nanohardness values for CAD than SD, which reduces after 1 year storage, for all surface treatments. Interface SEM analysis revealed that all adhesive interfaces, especially those in CAD, have experienced degradation after 1 year of storage. Laser 80 and Laser 50 promotes surface ablation characteristics in CAD and SD, as noted in surface SEM and collagen fibrils alterations observed in TEM. Despite of adhesive systems, bonding and nanohardness to CAD is lower than to SD. All tested adhesive interfaces were sensitive to saliva storage. Surface treatment with 50?s Er:YAG laser did not influence on bonding. (AU)

• FAPESP's process: 12/15089-4 - Screening Er:YAG (SSP) laser parameters to increase longitudinal adhesion to caries affected dentine
• Grantee: Cynthia Soares de Azevedo
• Support Opportunities: Scholarships in Brazil - Doctorate