Optimization of large MOD restorations: Composite resin inlays vs. short fiber-reinforced direct restorations

Luciana Mara Soares; Mehrdad Razaghy; Pascal Magne

doi:10.1016/j.dental.2018.01.004

Optimization of large MOD restorations: Composite resin inlays vs. short fiber-reinforced direct restorations

Dent Mater. 2018 Apr;34(4):587-597. doi: 10.1016/j.dental.2018.01.004. Epub 2018 Jan 20.

Authors

Luciana Mara Soares¹, Mehrdad Razaghy², Pascal Magne³

Affiliations

¹ Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, USC, 925 W 34th St, Los Angeles, CA 90089, USA. Electronic address: soareslumara@gmail.com.
² Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, USC, 925 W 34th St, Los Angeles, CA 90089, USA. Electronic address: razaghy@usc.edu.
³ Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, USC, 925 W 34th St, Los Angeles, CA 90089, USA. Electronic address: magne@usc.edu.

PMID: 29366492
DOI: 10.1016/j.dental.2018.01.004

Abstract

Objective: To compare mechanical performance and enamel-crack propensity of direct, semi-direct, and CAD/CAM approaches for large MOD composite-resin restorations.

Methods: 45 extracted maxillary molars underwent standardized slot-type preparation (5-mm depth and bucco-palatal width) including immediate dentin sealing (Optibond FL) for the inlays (30 teeth). Short-fiber reinforced composite-resin (EverX Posterior covered by Gradia Direct Posterior) was used for the direct approach, Gradia Direct Posterior for the semi-direct, and Cerasmart composite resin blocks for CAD/CAM inlays. All inlays were adhesively luted with light-curing composite-resin (preheated Gradia Direct Posterior). Shrinkage-induced enamel cracks were tracked by transillumination photography. Cyclic axial isometric chewing (5-Hz) was simulated, starting with a load of 200N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200, and 1400N (maximum 30,000 cycles each) until fracture or to a maximum of 185,000 cycles. Survived specimens were subjected to cyclic-load-to-failure test at 30-degree angle on the palatal cusp.

Results: Only small shrinkage-induced cracks were found in 47% of the direct restorations compared to 7% and 13% of semi-direct and CAD/CAM inlays, respectively. Survival to accelerated fatigue was similar for all three groups (Kaplan-Meier p>.05) and ranged between 87% (direct) and 93% (semi-direct and CAD/CAM). Cyclic-load-to-failure tests did not yield significant differences either (Life Table analysis, p>.05) with median values of 1675N for CAD/CAM inlays, 1775N for fiber-reinforced direct restorations and 1900N for semi-direct inlays.

Significance: All three restorative techniques yielded excellent mechanical performance above physiological masticatory loads. Direct restorations performed as good as inlays when a short-fiber reinforced composite-resin base was used.

Keywords: CAD/CAM; Composite resin; Crack propensity; Fatigue resistance; Short fibers; Shrinkage stress.

Publication types

Comparative Study

MeSH terms

Composite Resins / chemistry*
Computer-Aided Design
Dental Enamel / chemistry
Dental Materials / chemistry
Dental Restoration Failure
Dental Restoration, Permanent / methods*
Dental Stress Analysis
Humans
In Vitro Techniques
Inlays / methods*
Materials Testing
Molar
Resin Cements
Surface Properties
Transillumination

Substances

Composite Resins
Dental Materials
EverX Posterior
Gradia
OptiBond FL
Resin Cements