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Lasers Med Sci (2013) 28:879889 DOI 10.1007/s10103-012-1169-1
ORIGINAL ARTICLE
Shear strength of composite bonded to Er:YAG laser-prepared enamel: an in vitro comparative study
Frank Y. W. Yung & Norbert Gutknecht &
Rene Franzen & Horst Fischer
Received: 22 October 2011 /Accepted: 16 July 2012 /Published online: 2 August 2012 # Springer-Verlag London Ltd 2012
Abstract The primary objective of this study is to investigate the adhesion properties between four current generations of bonding systems and enamel surface conditioned by Er:YAG laser, using an energy density comparable to the ablation threshold of enamel. By including an energy density comparable to published adhesion studies, the secondary objective is to compare the adhesion effects of these selected laser conditioning parameters on enamel with other similar published studies. Material and methods: Buccal sides of randomly selected human molars (N0117) were prepared and divided into nine experimental groups depending on the generations of bonding system represented by the corresponding number (G4, G5, G6, G7) and the additional laser conditioning on the enamel surface represented by laser etch (LE) and laser etch with a higher pulse energy, followed by acid etch (AE), if required. The bonding resin systems and their specific requirements were applied after the enamel surfaces were laser conditioned following a specific set of laser parameters. Composite posts of1.6 mm in diameter and approximately 6 mm in length were then restored on each of the sample surfaces. After 48 h, the
composite assemblies were tested to failure under compression using a knife edge loading head at a cross head speed of 1 mm/min until the composite cylinders were separated from the surface. The data collected were then analyzed using one-way analysis of variance and SAS software program (9.1, TS1M3). Results: No significant difference was found among these groups: AE+G4/LEAE+G4, G6/LE+ G6, and G7/LE+G7. Significant differences were found in the remaining groups: AE+G5/LEAE+G5, AE+G5/LEAEH+G5, and LEAE+G5/LEAE-H+G5. The bond strength results were compared among similar published data and possible influences from different laser parameters, bonding systems, and their combined impact on the enamel surface and its adhesion properties were analyzed. Conclusion: Under our specific settings, additional laser conditioning after phosphoric acid etch is beneficial to one generation of bonding resin (G5). There is no significant change or detrimental effect to...