Influence of storage temperature on vickers microhardness of resin composite

Abstract

The purpose of this study is to evaluate the effect of three storage temperatures on microhardness of high-and low-viscosity bulk-fill materials and compare them with conventional resin-based composite materials. Material and Methods: Six composite resin-based materials were used in this study (TN, TNB, TNF, FZ250, FB, and FBF), samples were subdivided into three groups based on the pre-curing storage temperature (5°C, 23°C, 37°C). Light polymerization for each material was performed based on the manufacturer's recommendation using a Bluephase G2 curing unit (Ivoclar Vivadent, Schaan, Liechtenstein) in a high-intensity mode with an irradiance of 1200 mW/cm 2. Vickers hardness values of the top and the bottom surfaces of each sample were evaluated using a NOVA 130series, Vickers and Knoop hardness testing instrument under a 200-gram load and a dwell time of 10 seconds. Results: When the tested materials were stored at room temperature (23°C) before testing in the present study, they failed to reach the minimum 80% of the mean bottom to top hardness value ratio except for FZ250 and FBF, where they reached 97.8% and 83.2% respectively. Conclusion: Despite the promising results from this preliminary study, regarding improvement of microhardness with refrigerated composite resins, further research has to be conducted. The enhancement of hardness values associated with preheated composites could be beneficial in countries with warm climates, such as Saudi Arabia.

Effect of Different Storage Temperatures on Degree of polymerization of Tetric Evoceram Bulk Fill Composite resin (An in vitro study)

“…Temperatures factor play an important role in the polymerization process, which alter the mechanical and physical properties of composite resin, composite is a viscoelastic material, which responds to an increase or decrease in the external temperature. (4) Dentists store composite resins in refrigerators to prolong their shelf lives usually at temperatures ranging from 2°Cto 5°C as recommended by the manufactures (5) . Darnoch et al (2006) reported that the degree of polymerization is decreased at 3°C and increased at a 60°C (6) .…”

Análise de propriedades químicas e mecânicas de diferentes resinas compostas quando mantidas em temperatura de refrigerador e ambiente

“…Considering the clinical indication, the materials designated to the posterior region showed greater potential to increase hardness when stored at room temperature (Chi-square Test -p=0.047). Hardness tests data for a specific material provide information about its wear, polish ability and abrasive effect on antagonist teeth 31 . The surface hardness of a composite resin is influenced by resin matrix, filler particle shape, distribution, size and density.…”