Introduction: When aesthetics is compromised, dental ceramics are excellent materials for dental restorations; owing to their optical properties and biocompatibility, zirconia ceramics are particularly interesting. Self-adhesive resin cements are the most suitable for bonding to zirconia ceramics, but traditional adhesive chemistry is ineffective and surface treatments are required to improve the adhesive bonding between resin and zirconia. The aim of this study was to evaluate the effect of femtosecond laser treatment on the shear bond strength (SBS) of self-adhesive resin cement on zirconia surfaces and to contrast it with other different surface conditioning methods.
Methods: Sixty square-shaped zirconia samples were divided randomly into four groups (n = 15) according to their surface conditioning method: the NT group - no surface treatment; the APA25 group - airborne abrasion with 25 μm alumina particles; the TSC group - tribochemical silica coating, and the FS group - femtosecond laser irradiation (800 nm, 4 mJ, 40 fs/pulse, 1 kHz). Self-adhesive resin cements were bonded at the centre of samples, and after 72 hours, they were tested for SBS with a universal testing machine at a crosshead speed of 0.5 mm/min, until fracture. Five zirconia surfaces for each group were subjected to a surface morphology analysis by scanning electron microscopy (SEM). The failure modes were noted and a third of the specimens were prepared to morphological analysis.
Results: The NT group showed lower SBS values than the other groups. Femtosecond laser treatment demonstrated higher values than the control and APA25 groups and similar values to those of the TSC group. In the APA25 group, the surface conditioning method had values close to those of the TSC group, but lower than those obtained with femtosecond laser treatment.
Conclusion: The treatment of zirconia with femtosecond laser irradiation created a consistent and profound surface roughness, improving the adhesive effectiveness of the zirconia-resin interface.
Denry I, Kelly JR. State of the art of zirconia for dental applications. Dent Mat. 2008;24:299-307. doi:10.1016/j. dental.2007.05.007.
Vagkopoulou T, Koutayas S, Koidis P, Strub JR. Zirconia in Dentistry: Part 1. Discovering the nature of an upcoming bioceramic. Eur J Esthet Dent. 2009;4:130-51.
Manicone PF, Iommetti PR, Raffaelli L. An overview of zirconia ceramics: basic properties and clinical applications. J Dent. 2007;35:819-826. doi:10.1016/j.jdent.2007.07.008.
Gomes AL, Montero J. Zirconia implant abutments: a review. Med Oral Pato Oral Cir Bucal. 2011;16:50-55. doi:10.4317/medoral.16.e50.
Ozcan M, Bernasconi M. Adhesion to zirconia used for dental restorations: a systematic review and meta-analysis. J Adhes Dent. 2015;17:7-26.
Calvalti AN, Foxton RM, Watson TF, Oliveira MT, Giannini M, Marchi GM. Y-TZP ceramics: key concepts for clinical application. Oper Dent. 2009;34:344-351. doi:10.2341/08- 79.
Nakonieczny D, Walke W, Majewska J, Paszenda Z. Characterization of magnesia-doped yttria-stabilized zirconia powders for dental technology applications. Acta Bioeng Biomech. 2014;16:99-106.
Kosmac T, Oblak C, Jevnikar P, Funduk N, Marion L. Strength and reliability of surface treated Y-TZP dental ceramics. J Biomed Mater Res. 2000;53:304-313.
El-Korashy DI, El-Refai DA. Mechanical properties and bondig potencial of partially stabilized zirconia treated with different chemomechanical treatments. J Adhes Dent. 2014;16:365-376.
Ferracane JL, Stansburry JW, Burke FJT. Self-adhesive resin cements–chemistry, properties and clinical considerations. J Oral Rehabil. 2011;38:295-314. doi:10.1111/j.1365- 2842.2010.02148.x.
Casucci A, Goracci C, Chieffi N, et al. Microtensile bond strength evaluation of self-adhesive resin cement to zirconia ceramic after different pre-treatments. Am J Dent. 2012;25:269-275.
Maeda FA, Bello-Silva MS, de Paula Eduardo C, Miranda Junior WG, Cesar PF. Association of different primers and resin cements for adhesive bonding to zirconia ceramics. J Adhes Dent. 2014;16:261-265.
Kern M, Wegner SM. Bonding to zirconia ceramic: adhesion methods and their durability. Dent Mater. 1998;14:64-71. doi:10.1016/s0109-5641(98)00011-6.
Elsaka SE. Effect of surface treatments on the bonding strength of self-adhesive resin cements to zirconia ceramics. Quintessence Int. 2013;44:407.
Usumez A, Hamdemirci N, Koroglu BY, Simsek I, Parlar O, Sari T. Bond strength of resin cement to zirconia ceramic with different surface treatments. Lasers Med Sci. 2013;28:259-566. doi:10.1007/s10103-012-1136-x.
Moradabadi A, Roudsari SE, Yekta BE, Rahbar N. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic. Mater Sci Eng C Mater Biol Appl. 2014;34:311-317. doi:10.1016/j.msec.2013.09.015.
Akin H, Ozkurt Z, Kımalı O, Kazazoglu E, Ozdemir A. Shear bond strength of resin cement to zirconia ceramic after aluminium oxide sandblasting and various laser treatments. Photomed Laser Surg. 2011;29:797-802. doi:10.1089/ pho.2011.3039.
Gomes AL, Castillo-Oyagüe R, Lynch CD, Montero J, Albaladejo A. Influence of sandblasting granulometry and resin cement composition on microtensile bond strength to zirconia ceramic for dental prosthetic frameworks. Am J Dent. 2013;4:31-41. doi:10.1016/j.jdent.2012.09.013.
Sarmento HR, Campos F, Sousa RS, et al. Influence of air-particle deposition protocols on the surface topography and adhesion of resin cement to zirconia. Acta Odontol Scand. 2014;72:346-353. doi:10.3109/00016357.2013.837958.
May LG, Passos SP, Capelli DB, Ozcan M, Bottino MA, Valandro LF. Effect of silica coating combined to a MDP-based primer on the resin bond to Y-TZP ceramic. J Biomed Mater Res B Appl Biomater. 2010;95:69-74. doi:10.1002/ jbm.b.31684.
Queiroz JR, Massi M, Nogueira L Jr, Sobrinho AS, Bottino MA, Ozcan M. Silica-based nano-coating on zirconia surfaces using reactive magnetron sputtering: effect on chemical adhesion of resin cements. J Adhes Dent. 2013;15:151-159.
Gomes AL, Ramos JC, Santos del Riego S, Montero J, Albaladejo A. Thermocycling effect on microshear bond strength to zirconia ceramic using Er.YAG and tribochemical silica coating as surface conditioning. Laser Med Sci. 2015;30:787-795. doi:10.1007/s10103-013-1433-z.
Kasraei S, Rezaei-Soufi L, Heidari B, Vafaee F. Bond strength of resin cement to CO2 and Er:YAG laser-treated zirconia ceramic. Restor Dent Endod. 2014;39:296-302. doi:10.5395/ rde.2014.39.4.296.
Kara O, Kara HB, Tobi ES, Ozturk AN, Kilic HS. Effect of various lasers on the bond stregth of two zirconia ceramics. Photomed Laser Surg. 2015;33:69-76. doi:10.1089/ pho.2014.3841.
Aboushei MN. Evaluation of zirconia/resin bond strength and interface quality using a new technique. J Adhes Dent. 2011;13:255-260.
Cvikl B, Dragic M, Franz A, Raabe M, Gruber R, Moritz A. Long-term storage affects adhesion between titanium and zirconia using resin cements. J Adhes Dent. 2014;16:459- 464.
Lorenzo MC, Portillo M, Moreno P, et al. In vitro analysis of femtosecond laser as an alternative to acid etching for achieving suitable bond strength of brackets to human enamel. Lasers Med Sci. 2014;29:897-905. doi:10.1007/ s10103-013-1278-5.
Lorenzo MC, Portillo M, Moreno P, et al. Ultrashort pulsed laser conditioning of human enamel: in vitro study of the influence of geometrical processing parameters on shear bond strength of orthodontic brackets. Laser Med Sci. 2015;30:891-900. doi:10.1007/s10103-013-1491-2.
Akpinar YZ, Irgin C, Yavuz T, Aslan MA, Kilic HS, Usumez A. Effect of femtosecond laser treatment on the shear bond strength of a metal bracket to prepared porcelain surface. Photomed Laser Surg. 2015;33:206-212.
Camposilvan E, Marro FG, Mestra A, Anglada M. Enhanced reliability of yttria-stabilized zirconia for dental applications. Acta Biomater. 2015;17:36-46.
Passos SP, May LG, Barca DC, Ozcan M, Bottino MA, Valandro LF. Adhesive quality of self-adhesive and conventional adhesive resin cement to Y-TZP ceramic before and after aging conditions. Oper Dent. 2010;35:689- 696. doi:10.2341/10-157-l.
Inokoshi M, de Munck J, Minakuchi S, Van Meerbeek B. Meta-analysis of bonding effectiveness to zirconia ceramics. J Dent Res. 2014;93:329-334. doi:10.1177/0022034514524228.
Luengo MC, Portillo M, Sánchez JM, et al. Evaluation of micromorphological changes in tooth enamel after mechanical and ultrafast laser preparation of surface cavities. Lasers Med Sci. 2013;28:267-273. doi:10.1007/ s10103-012-1144-x.
Portillo M, Luengo MC, Sánchez JM, et al. Morphological alterations in dentine after mechanical treatment and ultrashort pulse laser irradiation. Lasers Med Sci. 2012;27:53-58. doi:10.1007/s10103-010-0845-2.
Pike P, Parigger C, Splinter R, Lockhart P. Temperature distribution in dental tissue after interaction with femtosecond laser pulses. Appl Opt. 2007;46:8374-8378. doi:10.1364/ao.46.008374.
Girard B, Cloutier M, Wilson DJ, Clokie CMI, Miller RJD, Wilson BC. Microtomographic analysis of healing of femtosecond laser bone calvaria wounds compared to mechanical instruments in mice with and without application of BMP-7. Lasers Surg Med. 2007;39:458-467.
Liu D, Tsou JK, Matinlinna JP, Wong HM. Effects of some chemical surface modifications on resin zirconia adhesión. J Mech Behay Biomed Mater. 2015;46:23-30.
Kirmali O, Kustarci A, Kapdan A, Er K. Efficacy of surface roughness and bond strength of Y-TZP zirconia after various pre-treatments. Photomed Laser Surg. 2015;33:15- 21. doi:10.1089/pho.2014.3825.
De Oyagüe RC, Moticelli F, Toledano M, Osorio E, Ferrari M, Osorio R. Influence of surface treatments and resin cement selection on bonding to densely-sintered zirconium-oxide ceramic. Dent Mater. 2009; 25:172-179. doi:10.1016/j. dental.2008.05.012.