Is there a correlation between physical properties and film thickness of dual- and photo-polymerized resin cements and CAD/CAM-dentin micro-tensile bond strength?

Abstract

To correlate µTBS of different resin cements with their film thickness (FT), Vickers hardness (HV), and ultimate tensile strength (UTS). Human molars (N = 30) were divided into six-groups according to 1: Resin cement: Bifix QM, (BF), GrandioSo Heavy Flow (GHF) and VisCalor Bulk (VB), and 2: Adhesive mode (Optibond Universal): Etch-and-rinse (E&R) or self-etching (SE). CAD/CAM blocks (7 × 7 × 4 mm³) were air-abraded using 50 μm Al₂O₃ and silane was applied (60 s), and air dried (10 s). For E&R, dentin was etched (15 s), rinsed (30 s), and blot-dried. For both modes, adhesive was applied (20 s), air-dried (5 s), and photo-polymerized (10 s). Sticks (1 × 1 mm²) were stored for 24-h or 6-months. Sticks were pulled in tension (1 mm/min). Debonded sticks were evaluated for failure mode analysis. For FT, nine-bonded slabs from each cement was prepared and evaluated. For UTS, eight-hourglass specimens from each cement were prepared and tested in tension. For HV, five-discs from each cement was prepared and evaluated using a HV tester. Data were analyzed using ANOVA/Pearson’s correlation tests (α = 0.05). No correlation between µTBS/HV was revealed (p > 0.05). A positive correlation between µTBS/FT and µTBS/UTS (p < 0.05) was observed. Three-way ANOVA revealed all experimental factors had a significant effect on µTBS (p < 0.05). The VB showed significantly lower µTBS (20.8 ± 9.3 MPa). The E&R mode showed higher µTBS (26.0 ± 10.9 MPa), and 24-h revealed a higher µTBS (27.4 ± 10.0 MPa). Mixed failure was the predominant type (42.51%). The VB showed the highest FT (122.2 ± 11.9 µm), with GHF revealed higher UTS and HV (112.5 ± 19.7 MPa and 91.6 ± 0.4 Kgf, respectively). Photo-polymerized flowable composite can substitute dual-polymerized cement for CAD/CAM composite bonding.

Keywords:

• Adhesion
• CAD/CAM composite
• dental materials
• resin cement
• resin composite
• dentin bond strength
• Vickers hardness
• ultimate tensile strength

Acknowledgment

The authors acknowledge VOCO GmbH, Cuxhaven, Germany for supplying THE CAD/CAM blocks, silane coupling agent and resin composites tested in this study.

Ethical approval

This study was approved by Ethics Committee Board, Faculty of Dentistry, Ain Shams University No. FDASU-Rec-PC012461.

Author contributions

Conceptualization: Farid El-Askary, Mutlu Özcan, Nader Tadros, Abdullah Hassanien, Mohamed Amer Kamel. Methodology: Farid El-Askary, Mutlu Özcan, Nader Tadros, Abdullah Hassanien, Emad Aboelazm, Mohamed Amer Kamel. Formal analysis: Farid El-Askary. Investigation: Farid El-Askary, Abdullah Hassanien, Nader Tadros. Writing-Original draft preparation: Farid El-Askary, Mutlu Özcan. Writing-review and editing: Farid El-Askary, Mutlu Özcan. Resources: Abdullah Hassanien, Nader Tadros. Supervision: Farid El-Askary, Mohamed Amr Kamel. All the authors have read and agreed to the published version of the manuscript.

Clinical significance

Photo-polymerized heavy-flow flowable composite and the thermos-viscous bulk-fill resin composite can be viable alternatives to the dual-polymerized resin cement for CAD/CAM composite/dentin bonding.

The authors acknowledge that the manuscript is a preprint on Research Square and not under review or published in any other journal. Part of this work was presented as poster presentation at the international Academy of Adhesive Dentistry (IAAD) meeting, Zurich, 16-17^th June 2023. This study is a part of Nader Tadros’s Ph.D. Thesis, partially fulfilling the requirements of the Doctor Degree in Operative Dentistry, Faculty of Dentistry, Ain Shams University.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This study had no external fund.