Mechanical Degradation of Different Classes of Composite Resins Aged in Water, Air, and Oil.

Weber Adad Ricci,Priscila Alfano,Saulo Pamato,Carlos Alberto Dos Santos Cruz,Jefferson Ricardo Pereira

doi:10.1155/2019/7410759

Weber Adad Ricci, Priscila Alfano + Show 3 more

Open Access

https://doi.org/10.1155/2019/7410759

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Abstract

A significant deterioration of the properties can drastically compromise the survival rate of restorative materials. The aim of this study was to assess flexural strength and hardness of three composite classes: hybrid composite resin (HCR), nanoparticulate composite resin (NCR), and silorane-based composite resin (SBCR). One hundred specimens were prepared for hardness testing by using a split metallic mold measuring 10 mm in diameter and 2 mm deep. Twenty specimens were prepared for each restorative material, randomly assigned for storage in air, distilled water, or mineral oil. After intervals of 24 hours, 30, 60, 90, and 120 days, hardness and flexural strength tests were initially compared in two levels: “storage medium” and “time” within each material group. A two-way analysis of variance was performed (p<0.05) on the variables “material” and “storage time” (p<0.05). The HCR showed to be stable with regard to the evaluation of flexural strength and hardness (p<0.05). A significant reduction occurs for the NCR in comparison to the other groups (p<0.05). The NCR presented the lowest values of hardness and flexural strength kept on water over time. The characteristics of material showed a strong influence on the decrease of the mechanical properties analyzed.

Highlights

Dental composites have been developed as an aesthetic alternative to the old amalgam-based restorative material and have become the most widely used materials in current dental practice. [1, 2] They became popular because of their ability to reproduce the natural color of teeth, are mercury-free, have low thermal conductivity, and adhere to tooth structure through adhesive systems. [3]
The authors tested the null hypothesis that stated that there is no difference in flexural strength and hardness for the three composite classes, and behavior of the tested materials is similar for the three storage mediums at different storage times
It does not emphasize the detected resistance loss after 30 days of storage. In this table, a decrease around 18% can be observed for the hybrid composite resin (HCR) in the three storage mediums after the initial evaluation

Summary

Introduction

Dental composites have been developed as an aesthetic alternative to the old amalgam-based restorative material and have become the most widely used materials in current dental practice. [1, 2] They became popular because of their ability to reproduce the natural color of teeth, are mercury-free, have low thermal conductivity, and adhere to tooth structure through adhesive systems. [3]Despite the fact that technological advancements have encouraged the use of these materials in areas subjected to intense functional stress, physicochemical stability is necessary for these products to have acceptable longevity. Among the most significant factors contributing to the failure of composite resins over time are the loss of brightness, dental stains, marginal infiltration, recurrent decay, dental wear, and fractures. With regard to the monomers that make up the composite resins, one of the most recent studies within the field of dental materials was the introduction of silorane-based resins as a substitute for methacrylate-based resins. [6] Siloranebased resin is derived from oxirane and siloxane molecules that polymerize with cationic ring opening, overcoming clinical disadvantages of polymerization shrinkage of the well-established methacrylate-based materials. Bis-GMA, TEGDMA zirconia/silica 4.5 μm (maximum size)

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