Flexural strength and surface microhardness of materials used for temporary dental disocclusion submitted to thermal cycling: An in vitro study Tamires Borges de Lima 1 , José Guilherme Neves 2 , Ana Paula Terossi de Godoi 3 , Ana Rosa Costa 2 , Viviane Veroni Degan 3 , Américo Bortolazzo Correr 2 , Heloisa Cristina Valdrighi 3 1. Department of Dentistry, Fundação Hermínio Ometto, FHO - Uniararas, Araras, SP, Brazil 2. Department of Restorative Dentistry - Dental Materials Division, Piracicaba Dental School, Areião, Piracicaba, SP, Brazil 3. Department of Orthodontics, School of Dentistry of Araras, Uniararas, SP, Brazil Correspondence: José Guilherme Neves, Department of Restorative Dentistry - Dental Materials Division, Piracicaba Dental School, Unicamp, Av. Limeira, 901, Areião, 13414-903 Piracicaba, SP, Brazil. nevesjoseguilherme@gmail.com ORTHO-476 Available online: Keywords Hardness tests Dental materials Composite resins Orthodontics Glass ionomer cements Summary Objective > The objective of this study was to evaluate the effect of temperature variation on surface microhardness and resistance to flexion of different materials used for making a temporary dental disocclusion. Methods > One hundred specimens were made of the following materials (n = 20): glass ionomer cement (GIC); compomer (CP); composite resin (CR); Blue colour resin composite for temporary dental disocclusion (BTDD); ultraviolet colour resin composite for temporary dental disocclusion (UVTDD). They were stored in distilled water for 24 hours and, subsequently, half of the specimens in each group were subjected to thermal cycling (n = 10). All samples were subjected to the microhardness test (HMV-2000) and the flexural strength analysis (INSTRON). The data were submitted to parametric statistical analysis (ANOVA) and Tukey's complementary test with a significance level of 5%. In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P < 0.05) was responsible for the reduction of the values found, except for GIC. Results > In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P < 0.05) was responsible for the reduction of the values found, except for GIC. For microhardness, the highest average was found for BTDD and UVTDD (P  0.05). As for the resistance, the flexion was found that in the groups not submitted to thermal cycling there was no statistically significant difference for all materials, except for GIC, for the groups with To cite this article: Borges de Lima T, et al. Flexural strength and surface microhardness of materials used for temporary dental disocclusion submitted to thermal cycling: An in vitro study. International Orthodontics (2020), https://doi.org/10.1016/j. ortho.2020.04.003 tome xx > 000 > xx 2020 https://doi.org/10.1016/j.ortho.2020.04.003 © 2020 CEO. Published by Elsevier Masson SAS. All rights reserved. 1 Original Article International Orthodontics 2020; //: /// Websites: www.em-consulte.com www.sciencedirect.com