Long-term tensile bond strength of differently cemented nanocomposite CAD/CAM crowns on dentin abutment

ObjectivesTo test the tensile bond strength of luted composite computer aided design/computer aided manufacturing (CAD/CAM) crowns after use of different adhesive systems combined with different resin composite cements on dentin abutments.MethodsHuman molars (n = 200) were embedded in acrylic resin, prepared in a standardized manner and divided into 20 groups (n = 10). The crowns were treated as follows: (i) Monobond Plus/Heliobond (MH), (ii) Ambarino P60 (AM), (iii) Visio.link (VL), (iv) VP connect (VP), and (v) non-treated as control groups (CG) and luted with Variolink II (VAR) or Clearfil SA Cement (CSA). Tensile bond strength (TBS) was measured initially (24 h water, 37 °C) and after aging (5000 thermal cycles, 5/55 °C). The failure types were evaluated after debonding. TBS values were analyzed using three-way and one-way ANOVA, followed by post hoc Scheffé-test, and two-sample Student's t-tests.ResultsAmong VAR and after aging, CG presented significantly higher TBS (p = 0.007) than groups treated with MH, AM and VP. Other groups showed no impact of pre-treatment. A decrease of TBS values after thermal aging was observed within CSA: CG (p = 0.002), MH (p < 0.001), VL (p < 0.001), AM (p = 0.002), VP (p < 0.001) and within VAR: MH (p = 0.002) and AM (p = 0.014). Groups cemented with VAR showed significantly higher TBS then groups cemented with CSA: non-aged groups: CG (p < 0.001), and after thermal aging: CG (p = 0.003), MH (p < 0.001), VL (p = 0.005), VP (p = 0.010).SignificanceAccording to the study results nano-composite CAD/CAM crowns should be cemented with VAR. Pre-treatment is not necessary if the tested resin composite cements are used.