Effect of repeated autoclave on hardness, tensile and compressive strength of polypropylene/natural rubber developed for rubber dam clamp

This research investigates the potential use of polypropylene (PP) and natural rubber (NR) blends as an alternative to conventional stainless steel rubber dam clamps typically used in dentistry. The hardness, tensile and compressive strength of various PP/NR blend ratios were assessed. One-way ANOVA test results found that PP/NR blends exhibit significantly lower hardness (p<0.001) than the commercial SoftClampTM. The findings indicated that PP/NR ratios of 100/0, 90/10, and 80/20 exhibit hardness levels of 82%, 80%, and 75%, respectively. Subsequently, these specific PP/NR blend ratios undergo simulation of clinical sterilization processes through 1, 5, and 10 autoclave cycles. Two-way ANOVA revealed significant reductions in hardness (p<0.001), tensile strength (p<0.001) and compressive strength (p<0.001) with increasing NR content across all autoclave cycles. However, post-autoclave assessments at 1, 5, and 10 cycles demonstrated no statistically significant differences in tensile strength (p=0.058), hardness strength (p=0.52) and compressive strength (p=0.979) for PP/NR ratios of 100/0, 90/10, and 80/20 compared to their pre-autoclave states. The study concludes that the NR content within PP/NR blends decreases hardness, tensile and compressive strength while autoclaving does not significantly affect the hardness, tensile and compressive strength of PP/NR blends.