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Abstract
Background
This study investigated the impact of luting procedure and restoration thicknesses on the flexural strength of CAD/CAM restorations. Traditional luting agents have been questioned in favor of pre-heated resin composites or flowable composites.
Materials and Methods
400 disc-shaped restorations (lithium disilicate [IPS e.max CAD] or resin composite [Tetric CAD, Ivoclar]) were cemented onto dentin analog discs using different procedures (n = 20): dual-curing resin cement (Panavia V5), light-curing resin cement (Panavia Veneer LC), pre-heated resin composite (Clearfil™ AP-X) with or without pre-heated restoration, and high-filled flowable composite (Clearfil Majesty™ Flow). The biaxial flexural strength was calculated.
Results
There were significant effects of material, thickness, and luting procedure on flexural strength (p < 0.001). Resin composite specimens exhibited lower flexural strength (90 MPa) compared to lithium disilicate specimens (571 MPa), with thicker restorations (338 MPa) being stronger than thinner ones (323 MPa). Light-curing cement showed the highest strength (408.8 MPa)A, followed by dual-curing cement (362 MPa)B, pre-heated cement with pre-heated composite (318 MPa)C, pre-heated composite (304 MPa)C, and flowable resin composite (259 MPa)D. The light-curing cement yielded similar results to the pre-heated resin composite associated or not with the pre-heated crown for the thicker lithium disilicate specimens, whereas for the thinner lithium disilicate specimens all luting procedures performed similarly. Thin resin composite discs showed higher flexural strength when luted with light-curing cement, whereas the luting procedure had less influence for the thicker restorations.
Conclusion
Luting procedures impact the flexural strength of CAD/CAM lithium disilicate and resin composite restorations. Pre-heated resin composite, with or without pre-heated restoration, can replace dual-curing cement. Nevertheless, light-curing cement is superior for resin composite and 1.5 mm lithium disilicate restorations.
Key-messages
Different luting procedures significantly impact the flexural strength of CAD/CAM lithium disilicate and resin composite restorations, with light-curing cement demonstrating superior performance for specific thicknesses.
Pre-heated resin composites, either with or without pre-heated restorations, offer a viable alternative to conventional dual-curing cement for bonding indirect restorations, presenting potential clinical advantages.
Restoration thickness plays a crucial role in the mechanical response of restorations, with thinner resin composite restorations benefiting from dual- or light-curing, while thicker ones are less sensitive to luting procedure variations.
Acknowledgments
None.
Declaration of Interest statement
The authors declare no conflict of interest.
Author Contributions statement
Tribst J.P.M.: Conception and design, analysis and interpretation of the data, drafting of the paper, revising it critically for intellectual content and final approval of the version to be published.
Etoeharnowo, L: Conception and design, analysis and interpretation of the data, drafting of the paper, revising it critically for intellectual content and final approval of the version to be published.
Tadros M: Conception and design, analysis and interpretation of the data, drafting of the paper, revising it critically for intellectual content and final approval of the version to be published.
Feilzer A.J.: Analysis and interpretation of the data, revising the paper critically for intellectual content and final approval of the version to be published.
Werner A.: Analysis and interpretation of the data, drafting of the paper and final approval of the version to be published.
Kleverlaan C.J.: Conception and design, revising the paper it critically for intellectual content and final approval of the version to be published.
Dal Piva A.M.O.: Conception and design, drafting of the paper, revising it critically for intellectual content and final approval of the version to be published.
All authors agree to be accountable for all aspects of the work.
Data Availability Statement
Data will be available as requested.