Fiber reinforcement of a resin modified glass ionomer cement. Issue 12 (December 2020)

• Record Type: Journal Article
• Authors: Tanaka, Carina B.; Ershad, Frances; Ellakwa, Ayman; Kruzic, Jamie J.
• Is Part Of: Dental materials. Volume 36:Issue 12(2020)
• Page Start: 1516
• Page End: 1523
• Publication Date: 2020-12
• Subjects: Resin modified glass ionomer cement -- Fiber reinforcement -- Resin composite -- Mechanical properties -- Fracture toughness; Dentistry -- Periodicals; Dental materials -- Periodicals; 617.695
• DOI: 10.1016/j.dental.2020.09.003
• Languages: English
• ISSNs: 0109-5641

Abstract

Highlights: Fibers improve mechanical properties of a resin modified glass ionomer cement (RMGIC). Mechanical properties with RMGIC matrix are improved over GIC matrix. Braided long fibers give higher flexural strength than discontinuous short fibers. Resin pre-impregnation of braided long fibers greatly enhanced the flexural strength. Pre-impregnation of the short glass fibers had no effect on mechanical properties. Abstract: Objectives: Understand how discontinuous short glass fibers and braided long fibers can be effectively used to reinforce a resin modified glass ionomer cement (RMGIC) for carious lesion restorations. Methods: Two control groups (powder/liquid kit and capsule) were prepared from a light cured RMGIC. Either discontinuous short glass fibers or braided polyethylene fiber ribbons were used as a reinforcement both with and without pre-impregnation with resin. For the former case, the matrix was the powder/liquid kit RMGIC, and for the latter case the matrix was the capsule form. Flexural strength was evaluated by three-point beam bending and fracture toughness was evaluated by the single-edge V-notch beam method. Compressive strength tests were performed on cylindrical samples. Results were compared by analysis of variances and Tukey's post-hoc test. Flexural strength data were analyzed using Weibull statistical analysis. Results: The short fiber reinforced RMGIC both with and without pre-impregnation showed a significant increase of ∼50% in the mean flexural strength and 160–220% higher fracture toughness compared with the powder/liquid RMGIC control. Reinforcement with continuous braided fibers gave more than a 150% increase in flexural strength, and pre-impregnation of the braided fibers with resin resulted in a significant flexural strength increase of more than 300% relative to the capsule control. However, for the short fiber reinforced RMGIC there was no significant benefit of resin pre-impregnation of the fibers. The Weibull modulus for the flexural strength approximately doubled for the fiber reinforced groups compared to the control groups. Finally, compressive strength was similar for all the groups tested. Significance: By using a RMGIC as a matrix, higher flexural strength was achieved compared to reported values for short fiber reinforced GICs. Additionally, the short fibers provided effective toughening of the RMGIC matrix by a fiber bridging mechanism. Finally, continuous braided polyethylene fibers gave much higher flexural strength than discontinuous glass fibers, and their effectiveness was enhanced by pre-impregnation of the fibers with resin.