Investigation of mechanical and microbiological effects of different nanoparticle additions on maxillo facial prostheses

Silicone elastomers are preferred during the construction phase of maxillofacial prostheses thus their ideal mechanical properties. Silicone elastomers which used in maxillofacial prostheses are requiered to have high tear and tensile strength, ideal elongation percentage and hardness, high compatibility with tissues, and low microbial retention on their surfaces. The purpose of this study is to improve the mechanical and microbiological properties of silicone elastomer by adding various nanooxide particles to silicone elastomer. In the study, a total of four groups were formed together with the control group by adding 2% ZnO, SiO2 and TiO2 by heaviness to the silicone elastomer used in maxillofacial prostheses. In each group, a total of 92 samples were prepared, 11 samples for tensile strength and elongation percentage, 11 samples for tear strength, 11 samples for hardness test, 12 samples in each group for microbiological examination. Tensile strength and elongation percentage test samples were prepared in accordance with ASTM D412 standards, tear strength test samples in accordance with ASTM D624 standards, hardness test samples in accordance with ASTM D2240 standards. Samples of 7 mm diameter and 1 mm thickness were prepared for microbiological study. Tensile stress, elongation percentage, tear stress tests were carried out in Unıversal testing machine (LR 50K Lyodintruments Ltd, Fareham, UK) test device at a constant speed of 500 mm / min. Shore A test stand is used for hardness test. While examining the differences between groups, if the variables did not come from the normal distribution, Mann WhitneyU test was used for two-group comparisons and Kruskal Wallis-H Test for more than two groups. Kruskal-Wallis H-test, in case of the occurrence of significant differences were determined by post-hoc multiple comparison test group difference. Tukey HSD test was performed on the data of the hardness test. As a result of the research, a significant difference was found between the groups in terms of tensile strength, elongation percentage, tear strength and hardness test values (p <0.05). In the tensile strength test results, the highest group was seen in the group with SiO2 (3.35 Mpa ± 0.18), while the lowest was seen in the control group (2.64 Mpa ± 0.27). The tensile strength of the group with TiO2 added (3.22 Mpa ± 0.32) was determined to be higher than the tensile strength of the group with ZnO (2.73 Mpa ± 0.32). The highest value in the elongation percentage test results was 1017,23 for the TiO2 test group, and there was no significant difference between the other groups. In the tear strength test results, the highest value was found in the SiO2 test group (20.84 ± 2.17) and the lowest value in the control group (15.51 ± 1.79). There was no significant difference in tear strength between the group to which TiO2 was added (17.83 N/mm ± 1.61) and the group to which ZnO was added (17.93 N/mm ± 1.93). In the hardness test results, the highest hardness value was detected in the SiO2 group (25.50 N/mm ± 1.53), while the lowest value was found in the group with ZnO (21.85 N/mm ± 0.65). In the evaluation of antimicrobial efficacy, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans activities were evaluated, and no antimicrobial efficacy was detected. Keywords: Maxillofacial prostheses, mechanical property, microbiological feature, nanoparticle, silicone elastomer