Tensile bond strength of PMMA- and composite-based CAD/CAM materials to luting cements after different conditioning methods Christine Keul a , Anna Martin a , Timea Wimmer a , Malgorzata Roos b , Wolfgang Gernet a , Bogna Stawarczyk a,n a Department of Prosthodontics, Dental School, Ludwig-Maximilians University Munich, Goethestrasse 70, 80336 Munich, Germany b Division of Biostatistics, Institute of Social and Preventive Medicine, University of Zurich, Hirschgraben 84, 8001 Zurich, Switzerland article info Article history: Accepted 16 May 2013 Available online 28 June 2013 Keywords: CAD/CAM resin Tensile bond strength Resin cements Conditioning methods Adhesive systems Bonding Luting abstract This study investigated whether the adhesion of novel generation of polymeric CAD/CAM resins to luting cements would improve after use of different conditioning methods, and to evaluate the failure types after debonding. Two CAD/CAM resins (PMMA- and composite-based) were obtained (N¼600, n ¼15 per test group). The specimens were conditioned as follows: MH: Monobond Plus/Heliobond, VL: Visio.link, AM: Ambarino P60, VP: VP connect, CG: no conditioning as control group, and luted with conventional (Variolink II) or self-adhesive luting cement (Clearfil SA Cement). Two types of storage were performed: after 24 h water storage (37 1C) and additional 5000 thermal cycles (5 1C/55 1C). Tensile bond strength (TBS) was measured and data were analysed using 4/1-way ANOVA (Scheffé test), independent two- sample t-test and Chi 2 test (alpha ¼0.05). For both CAD/CAM resins, no or lower bonding was observed for the non-conditioned or AM groups, regardless of the luting cement. The conditioning with MH, VL and VP showed significant increase of TBS. In general, bonding on exp. CAD/CAM composite presented significant higher values compared to PMMA-based artBloc Temp. Variolink II showed higher TBS in combination with artBloc Temp. After conditioning with MH and VL predominantly cohesive failures in the luting cement were observed. All other groups showed adhesive failure. Aging level did not affect the TBS. The bonding properties of the CAD/CAM resin materials are dependent of the targeted selection of the conditioning method and luting cement. Composite-based materials showed higher bonding properties to luting cements than PMMA-based. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction The development of tooth coloured and cost-effective materials for dental restorations has gained greater significance as a consequence of the increasing demand. Fixed dental prostheses (FDPs) reconstruct the loss of tooth structure for a variety of reasons, as patients suffer for example from tooth decay or trauma in the daily clinical routine [1].A reliable cementation of the FDPs has an important role for the long- term success of the artificial denture. According to the composition of the cement and the conditioning of the tooth surface as well as the restoration, bonding emerges by mechanical retention, chemical reaction or the combination of both [1]. The bond strength between cement and alloys or different ceramics has been adequate investi- gated by several authors before [2–5]. Based on the introduction of CAD/CAM-systems for dentistry, the use of polymeric materials for long-term indirect restorations has distinctly expanded [6]. A major prerequisite for the large field of application are the significant improvements concerning the material properties over the last decade [7,8]. However, very limited informa- tion is available about the bonding properties between polymeric CAD/CAM resins and different cementing agents. Due to the high grade of conversion of these CAD/CAM resins, difficulties while cementation come along, as no bond to luting cement can be established without any further conditioning [9]. In addition, the authors reported about higher bond strength between tested materi- als than flexural strength of the composite resin (cohesive failure type), especially for combination of mechanical conditioning – like roughening of the surface – and further conditioning with adhesives. In this study four adhesive systems for the conditioning were used: a MMA solution, a light-cured MMA mixture included PETIA, a dimethacrylate based adhesive system with phosphor acidesters and phosphon acidesters as well as a light-cured dimethacrylate- based conventional adhesive system. On the one hand, “crosslinked” PMMA-based blanks were used as substrate, which consists of monomethylmethacrylate, without further organic or inorganic filler percentage. “Crosslinked” polymers with different chemical and physical natures, famous for the denture teeth, penetrate each other and become interlaced with the support of swelling processes. This “crosslinked” polymerisation causes an increase of mechanical and chemical properties. The other CAD/CAM Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ijadhadh International Journal of Adhesion & Adhesives 0143-7496/$ -see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijadhadh.2013.06.003 n Corresponding author. Tel.: +49 89 5160 9573. E-mail address: bogna.stawarczyk@med.uni-muenchen.de (B. Stawarczyk). International Journal of Adhesion & Adhesives 46 (2013) 122–127