Comparative investigation of the effect of molecular boron-containing compounds added to silicone elastomers used in maxillofacial prostheses on physical and mechanical properties

Aim: To evaluate the effect of h-BN nanoparticles on the physical and mechanical properties of silicone elastomers commonly used in maxillofacial prostheses. Material and Method: Two different types of silicone elastomers; M511 and VST-50 (Technovent, UK) were selected to be tested in our study. M511 is HTV type and VST-50 is RTV type silicone elastomers. The silicones were prepared according to the manufacturer's instructions and subjected to tensile strength, tear strength, percentage elongation and hardness tests. Groups of 10 samples each (n=10) were formed for the application of each test. A total of 80 samples were prepared from silicone elastomers, including the control group and the groups containing 1, 2 and 3 wt% h-BN nanoparticles, and a total of 240 samples were prepared for 3 different test methods (tensile, tear, hardness). SEM, EDS, FTIR Spectroscopy and XRD were used to analyse the silicon samples at molecular level. The data obtained from the mechanical tests applied to the samples were statistically analyzed. Results: Hexagonal boron nitride nanoparticle did not cause a significant difference in the tear strength and elongation percentage of M511 and VST-50 silicone elastomers and tensile strength of M511 silicone. The addition of hexagonal boron nitride to VST-50 silicone significantly decreased the tensile strength. In the hardness test, M511 silicone elastomer with 3% nanoparticles gave significantly higher results, while VST-50 silicone elastomer with 2% and 3% nanoparticles gave significantly lower results. SEM examination showed that nanoparticles were relatively more agglomerated in the groups containing 3% h-BN, and FTIR examination showed that nanoparticle molecules did not form chemical bonds with silicone molecules. Conclusion: The addition of 3 wt% h-BN nanoparticles to M511 silicone elastomer increased the hardness value. The addition of 2% and 3% h-BN to VST-50 silicone decreased the hardness value and tensile strength. It was concluded that increasing the nanoparticle concentration caused agglomeration in the nanoparticle and there was no chemical interaction between nanoparticle molecules and silicone molecules. Keywords: Elongation percentage, hardness, hexagonal boron nitride nanoparticle, maxillofacial prosthesis, silicone elastomer, tear strength, tensile strength.