Objectives: Aim of this study was to assess the performance of an experimental adhesive with core build-up materials.
Methods: Bovine incisors were embedded in cold-cure acrylic resin. The labial surface of each tooth was ground to expose enamel or dentin. A combination of an experimental adhesive (EXL-759,3M ESPE) and Scotchbond Multipurpose Plus Activator (3M ESPE) was applied to the tooth surface either after a 15s phosphoric acid etch (TE) or in the self-etch mode (SE). Core Paste XP (CP,DenMat), Rebilda DC (RBDC,Voco), Luxacore (LC,DMG), Core X flow (CXF,Dentsply), Clearfil DC Core (CDCC,Kuraray), Multicore HB (MCHB,Ivoclar-Vivadent) were filled into a Teflon mould (4.67mm diameter, 5mm height) and cured on the treated surfaces (n=5) in one increment using a Freelight 2 (3M ESPE, 40s). After 24h water storage at 37°C, shear bond strength (SBS) was measured using a Zwick Z010 universal testing machine (crosshead speed 2mm/min). Core Paste XP/Tenure A,B (CP,TEN,DenMat) was used as control.
Results: The table shows the SBS in MPa. The standard deviations (SD) are given in parentheses. All data per substrate were analyzed by ANOVA and multiple comparisons using Fisher's LSD procedure (p<0.05). Means with the same letters are statistically the same.
Materials | Enamel SBS (SD) [MPa] | Dentin SBS (SD) [MPa] |
CP_TEN_TE | 14.8(5.3)a | 6.6(3.3)A |
CP_EXL-759_TE | 19.6 (4.7)a | 12.1(3.8)B |
CP_EXL-759_SE | 12.6 (3.0)a | 14.3(2.1)B |
RBDC_EXL-759_TE | 20.7 (3.7)b | 18.4(5.9)C |
RBDC_EXL-759_SE | 12.0(4.3)a | 11.9(2.5)B |
LC_EXL-759_TE | 15.1(4.5)a | 11.6(3.9)B |
LC_EXL-759_SE | 11.0(1.9)a | 11.9(3.9)B |
CXF_EXL-759_TE | 22.5(4.6)b | 19.7(3.2)C |
CXF_EXL-759_SE | 9.7(1.9)a | 15.4(2.5)B |
CDCC_EXL-759_TE | 23.7(1.2)b | 15.4(2.8)B |
CDCC_EXL-759_SE | 17.7(7.7)a | 18.0(4.9)C |
MCHB_EXL-759_TE | 26.0(3.3)b | 22.9(5.4)C |
MCHB_EXL-759_SE | 15.7(4.4)a | 22.0(2.9)C |
Conclusion: Multiple statistically significant differences were found. EXL-759 had equivalent or higher SBS than the control. In order to maximize bond strength, etching of the enamel should be considered for low filled core build-up materials. Further studies are needed to investigate potential correlation between shrinkage effects and bond strength of core build-ups.