The aim of this study was to investigate the relationship between the different mechanical properties with the filler fraction of various resin composites. Mechanical properties of eighteen different resin composites were investigated in this study; flexural strength (FS), flexural modulus (FM), fracture toughness (FT), compressive strength (CS), diametral tensile strength (DTS), Barcol hardness (BH), Vickers hardness (HV), and Knoop hardness (HK). The mean values of mechanical properties and the filler fractions (V f ) obtained from the literature and the manufacturer were analyzed using Pearson's correlation test at p<0.01. The relationships were compared with the data retrieved from previous studies. Strong correlations between V f and BH/HV/HK and V f and FM were evident in the results of the present study and these results were supported by the retrieved data from previous studies. The other relationships between mechanical properties, such as that between FS and FM and between CS and HV were not significant.

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This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives:The quest for a happy life is accompanied by an increase in social activities, living standards, and socioeconomic development, with individuals showing increased interest in health and esthetics. In the field of dentistry, not only prevention and treatment but also esthetics is gaining popularity. The aim of this study was to identify tooth color reduction and consequent patient satisfaction over a period of 6 months after office and home bleaching. Methods: Thirty subjects were divided using the convenience sampling method into two groups based on the bleaching agent used: 10% carbamide peroxide (CP10; home bleach) and 15% hydrogen peroxide (office bleach). CP10 was used at home in a tray for 2 h/day over 14 days, while 15% hydrogen peroxide was light-activated for 15 min, three times/session (total, 45 min). A control set of teeth without any bleaching treatment was used as reference. Shade evaluation was conducted using the Shade Eye NCC at baseline, 1 week, and 1 and 6 months after bleaching. Data were analyzed using the MannWhitney U test and the nonparametric Friedman test. Results: There were significant differences in tooth color before and after bleaching in both the home and office bleach groups, although intergroup differences were not observed. Although b* values after bleaching were lower than the original values, only slight tooth color reduction was observed at 6 months. ΔE*, which represents the overall change in color, at 1 and 6 months after bleaching was significantly different from that at baseline in the home bleach group, while it showed no significant differences in the office bleach group. According to a patient satisfaction survey, patient satisfaction significantly increased over time in the home bleach group, although it did not differ significantly between groups. Conclusions: Tooth whitening was observed after bleaching in both groups. However, slight color reduction was observed at 6 months after bleaching, and complete restoration to the color before bleaching did not occur; therefore, long-term observation of color reduction is required.