Influence of Er:YAG laser pulse duration on the long-term stability of organic matrix and resin-dentin interface
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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 μs (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 (μSBS) 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 μSBS 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 μSBS 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 μSBS values at 24 h. The alterations on dentin’s organic structure did not jeopardize the μSBS after 1 year of saliva storage.
KeywordsEr:YAG laser Bond strength Dentin Pulse duration Long term
The authors would like to thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for the financial support given for the purchase of the laser equipment (Fidelis III-Fotona), Grant # 2015/12651-1.
This study was funded by FAPESP (2015/12651-1 and 2015/13571-1).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human third molars used in this in vitro study followed the approval of the Human Research Ethics Committee of the School of Dentistry of the University of São Paulo, Brazil (Protocol n. 124143/2015).
- 1.Van Meerbeek B, De Munck J, Yoshida Y, Inoue S, Vargas M, Vijay P et al (2003) Buonocore memorial lecture. Adhesion to enamel and dentin: current status and future challenges. Oper Dent 28:215–235Google Scholar
- 4.Agee KA, Prakki A, Abu-Haimed T, Naguib GH, Nawareg MA, Tezvergil-Mutluay A, Scheffel DL, Chen C, Jang SS, Hwang H, Brackett M, Grégoire G, Tay FR, Breschi L, Pashley DH (2015) Water distribution in dentin matrices: bound vs. unbound water. Dent Mater 31(3):205–116CrossRefPubMedPubMedCentralGoogle Scholar
- 6.Frassetto A, Breschi L, Turco G, Marchesi G, Di Lenarda R, Tay FR, Pashley DH, Cadenaro M (2016) Mechanisms of degradation of the hybrid layer in adhesive dentistry and therapeutic agents to improve bond durability –a literature review. Dent Mater 32(2):e41–e53. https://doi.org/10.1016/j.dental.2015.11.007 CrossRefGoogle Scholar
- 24.Lukac M, Marko M, Ladislav G (2004) Super VSP Er:YAG pulses for fast and precise cavity preparation. J Oral laser Applic 4:171–173. Medicine 9(4):338–344Google Scholar
- 27.Terrer E, Panayotov IV, Slimani A, Tardivo D, Gillet D, Levallois B, Fejerskov O, Gergely C, Cuisinier FJ, Tassery H, Cloitre T (2016) Laboratory studies of nonlinear optical signals for caries detection. J Dent Res 95(5):574–579. https://doi.org/10.1177/0022034516629400 CrossRefPubMedGoogle Scholar
- 35.Ramos AC, Esteves-Oliveira M, Arana-Chavez VE, de PaulaEduardo C (2010) Adhesives bonded to erbium:yttrium–aluminum– garnet laser-irradiated dentin: transmission electron microscopy, scanning electron microscopy and tensile bond strength analyses. Lasers Med Sci 25(2):181–189CrossRefPubMedGoogle Scholar
- 38.Nakabayashi N, Pashley DH (1998) Hybridization of dental hard tissues, 1st edn. Quintessence, TokyoGoogle Scholar
- 41.Feitosa VP, Sauro S, Ogliari FA, Ogliari AO, Yoshihara K, Zanchi CH, Correr-Sobrinho L, Sinhoreti MA, Correr AB, Watson TF, Van Meerbeek B (2014 Dec) Impact of hydrophilicity and length of spacer chains on the bonding of functional monomers. Dent Mater 30(12):e317–e323. https://doi.org/10.1016/j.dental.2014.06.006 CrossRefGoogle Scholar