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

OBJECTIVES: To 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. METHODS: Human 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 (24h water, 37 degrees C) and after aging (5000 thermal cycles, 5/55 degrees C). The failure types were evaluated after debonding. TBS values were analyzed using three-way and one-way ANOVA, followed by post hoc Scheffe-test, and two-sample Student's t-tests. RESULTS: Among 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). SIGNIFICANCE: According 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.