Abstract

OBJECTIVE: To evaluate the mechanical properties of three glass ionomers cements (GICs) used for band cementation in Orthodontics. METHODS: Two conventional glass ionomers (Ketac Cem Easy mix/3M-ESPE and Meron/Voco) and one resin modified glass ionomer (Multi-cure Glass ionomer/3M-Unitek) were selected. For the compressive strength and diametral tensile strength tests, 12 specimens were made of each material. For the microhardness test 15 specimens were made of each material and for the shear bond strength tests 45 bovine permanent incisors were used mounted in a self-cure acrylic resin. Then, band segments with a welded bracket were cemented on the buccal surface of the crowns. For the mechanical tests of compressive and diametral tensile strength and shear bond strength a universal testing machine was used with a crosshead speed of 1,0 mm/min and for the Vickers microhardness analysis tests a Microdurometer was used with 200 g of load during 15 seconds. The results were submitted to statistical analysis through ANOVA complemented by Tukey's test at a significance level of 5%. RESULTS: The results shown that the Multi-Cure Glass Ionomer presented higher diametral tensile strength (p < 0.01) and compressive strength greater than conventional GICs (p = 0.08). Moreover, Ketac Cem showed significant less microhardness (p < 0.01). CONCLUSION: The resin-modified glass ionomer cement showed high mechanical properties, compared to the conventional glass ionomer cements, which had few differences between them.

Highlights

  • How to cite this article: Farret MM, Lima EM, Mota EG, Oshima HMS, Maguilnik G, Scheid PA

  • Two conventional glass ionomer cements were used in the study: Meron® (Voco, Germany) batch 1090005093 and Ketac Cem easy mix® (3M/ESPE, USA) batch 370919 and a resin-modified glass ionomer Multi-cure Glass Ionomer® (3M/Unitek, USA) batch 8GG/8EU 2009-08

  • Assessment of the mechanical properties of glass ionomer cements for orthodontic cementation

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Summary

Methods

Two conventional glass ionomer cements were used in the study: Meron® (Voco, Germany) batch 1090005093 and Ketac Cem easy mix® (3M/ESPE, USA) batch 370919 and a resin-modified glass ionomer Multi-cure Glass Ionomer® (3M/Unitek, USA) batch 8GG/8EU 2009-08. For the compressive strength tests 12 cylindrical specimens of each material with dimensions of 3 x 6 mm were made with a metallic Teflon mold (Fig 1A). For the diametral tensile strength tests, 12 cylindrical specimens with dimensions of 6 x 3 mm for each material were made with a silicone matrix (Fig 1B). The materials were manipulated according to the manufacturer’s instructions on a glass plate with the aid of a plastic spatula. For the conventional glass-ionomer cements the conventional setting time of 10 minutes was anticipated whereas the resin-modified GIC was photopolymerized for 40 seconds with halogen light source Optilux® (3M/Unitek - USA) set at 400 mw/cm[2]. All specimens were placed in a container with 100% relative humidity for an hour and were immersed in distilled water at 37° C for 24 hours before mechanical testing

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