Influence of Er:YAG laser pulse duration on the long-term stability of organic matrix and resin-dentin interface

Author(s)

Trevelin, Livia Tosi ^{[1, 2]} ; Ferreira da Silva, Beatriz Togoro ^[1] ; de Freitas, Patricia Moreira ^[1] ; Matos, Adriana Bona ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Dent, Dept Operat Dent, Ave Prof Lineu Prestes 2227, Cidade Univ, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Cruzeiro Sul, Sch Dent, Dept Operat Dent, Ave Rua Galvao Bueno 868, BR-01506000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Lasers in Medical Science; v. 34, n. 7, p. 1391-1399, SEP 2019.
• Web of Science Citations: 0

Abstract

The purpose of this study was to explore the influence of Er:YAG laser irradiation with different pulse durations on the organic matrix, micromorphology of the hybrid layer (HL), and bond strength over time. Sixty caries-free human molars were cut to obtain flat dentin surfaces which were randomly divided into 4 groups: control (not irradiated-G1) and laser groups (80 mJ/2 Hz) with pulse duration ranging between 50 (G2), 300 (G3), and 600 mu s (G4). A self-etch adhesive system (Universal 3M ESPE) was applied on pre-treated dentin surfaces and cylinders of resin composite were built up and stressed in a universal testing machine (mu SBS) at 24 h and after12 months (n = 12). In addition, 3 other dentin-bonded specimens were prepared as previously described for each group with the adhesive doped with 0.1 wt% Rhodamine B to analyze hybrid layer morphology under Confocal Laser Microscope Scanning (CLMS). Organic matrix and collagen fibrils were analyzed by second harmonic generation (SGH). Two-way ANOVA and Tukey's test detected significantly higher mu SBS values for the control group, whereas the lower values were observed in all laser groups at 24 h (p < 0.05). Storage in artificial saliva did not reduce mu SBS in all groups. The low signal emitted by SHG images below the irradiated area demonstrated thermal damage of the collagen matrix. CLMS images of laser groups exhibited thicker and irregular resin-dentin interfaces than the control group. Regardless of the pulse duration, Er:YAG laser pre-treatment altered the organic matrix and HL formation which resulted in low mu SBS values at 24 h. The alterations on dentin's organic structure did not jeopardize the mu SBS after 1 year of saliva storage. (AU)

• FAPESP's process: 15/12651-1 - Influence of temporal width pulse of Er:YAG laser in dentin morphology, hybrid layer and bond strength
• Grantee: Lívia Tosi Trevelin
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/13571-1 - Er:YAG laser pulse width influence in dentin and esthetic restorative materials
• Grantee: Adriana Bona Matos
• Support type: Regular Research Grants