## 2 Materials and Methods
### Characteristics Investigated for the Selected Materials
#### 2.2.3 Mechanical Properties and Statistical Analyses  
The samples used for testing the mechanical properties were obtained in teflon molds and light-cured with a LED.E dental lamp (GuilinWoodpecker Medical Instruments Co., Guangxi, China) with a wave length of 470 nm and intensity of 950 mW cm. For each tested material (F00, F02, F03 and the experimental giomer) a number of 10 samples were fabricated.  
Before determining mechanical properties, all samples were stored for 24 h in a thermostatic bath at 37 \({}^{\circ}\)C. The containers were left to dry at room temperature and after another 24 h they were measured with a digital measurer. Mechanical properties were analyzed according to ISO 4049/2000 standard [27]. For measuring mechanical resistance properties, a Universal Testing Machine (LF Plus, LLOYD, Instrument, Ametek Inc., West Sussex, England) and Nexygen software was used.  
The samples for determining the compressive strength were of cylindrical shape, 8 mm high and 4 mm in diameter. The polymerization of the samples was performedin increments of 2 mm height, for 40 s each. The pressing speed of the machine was 0.75 mm /min.  
For the calculation of the compressive strength (CS) in MPa, the following formula was applied (1) [27]:  
\[CS=F/\pi r^{2} \tag{1}\]  
where \(F\) is the maximum applied strength (N), and \(r\) is the sample radius (mm).  
The Diametral Tensile Strength (DTS)  
For determining tensil strength, the diametral compression test was used. Samples were prepared in the same way as described for the compression strength test, having a cylindrical shape, 3 mm thick and 6 mm in diameter. The samples were pressed against the cylindrical generator. The force (\(F\)) acting on the cylinder, caught between the plates of the device, determines the appearance of the tensile forces on the vertical diameter plane. The calculation formula for tensile strength (DTS, measured in MPa) was applied as follows (2) [27]:  
\[DTS=2\times F/\pi\times D\times T \tag{2}\]  
where \(F\) is the maximum applied strength (N), and \(T\) is the thickness and \(D\) the diameter of the sample.  
Flexural Strength (FS) and Flexural Modulus  
For determining the flexural strength (\(FS\)), rectangular shaped samples were fabricated in a teflon mold, 25 mm in length, 2 mm height and 2 mm width. The light-curing of the samples was performed in 5 distinct areas along the sample, on both sides, for 20 s on each point. The samples were subjected to a three-point load with length (I) = 20 mm between the supports. The transverse speed of the test machine was 0.75 mm/min.  
For calculating the flexural strength (\(FS\)), the following formula was applied (3) [27]:  
\[FS=3 FI/2 bh^{2} \tag{3}\]  
where \(F\) is the maximum load applied to the specimen (N), \(l\) is the span between the supports (20 mm), and \(b\) and \(h\) are the width and height, of the specimen (mm), respectively.  
The [PERSON]'s modulus (YM) for bending determined the slope of the linear part of the force-deflection diagram.  
Statistical Analyses  
The data were analyzed with the ANOVA test and Tukey test for post-hoc comparison between sample groups; the significance level \(\alpha\) = 0.05. The statistical analysis was performed with the Origin2019b Graphing&Analysis software (OriginLab, Northampton, MA, USA).