effect of physical and chemical sterilization on the fracture resistance of orthodontic mini-implants: an in-vitro study

Aim: this study evaluated the effect of physical and chemical sterilization techniques on the fracture resistance of mini-implants. methods: thirty-two titanium mini-implants of 1.5 x 8 mm were randomly divided into four groups: control, steam sterilized, dry heat sterilized, and chemically sterilized. the samples were then tested in the air for fracture resistance using a universal testing machine. a tangential load was applied to the head of the mini-implant with a 1 mm/min crosshead speed after blocking each of them in the machine. also, the maximum load was recorded previous to screw fracture. he kruskal-wallis test and mann-whitney post hoc test were used for data analysis. results: the results of this study demonstrated the mean fracture resistance difference between the four groups was statistically significant at p<0.001. moreover it was showed the control group had significantly higher mean fracture resistance compared to dry heat and chemically sterilized groups at p=0.001 and p=0.009 respectively. this was followed by the stem sterilized group demonstrating significantly higher mean fracture resistance as compared to dry heat and chemically sterilized groups at p=0.001 and p=0.01 respectively. later, the chemically sterilized group also showed significantly higher mean fracture resistance as compared to the dry heat group at p=0.002. however, no significant difference was observed between the control and stem sterilized groups (p=0.29). conclusion: the steam sterilized group demonstrated the highest fracture resistance that was followed by the chemically sterilized group, and the least with the dry heat sterilized group.