## 4 Discussion  
The present study was based on the hypothesis that there would be no significant difference in mean Ra and RMS of ProTaper Gold files after ethanolic extract of _S. mukorossi_ and 17% EDTA solution compared to unused control files. Moreover, it was also hypothesized that 17% EDTA and ethanolic extract of _S. mukorossi_-treated files would not demonstrate any significant difference in Ra and RMS. Both the postulated hypothesis were rejected as both the irrigants demonstrated significant effect on Ra and RMS of tested files compared to the control group. Moreover, it was also found that EDTA causes more surface topographic changes on Protaper gold files compared to _S. mukorossi_. The Ra and RMS characterization of endodontic nitinol rotary files offer valuable information about surface defects, performance, and associated limitations [25]. The evaluation of surface topography and biomaterial interfaces through atomic force microscopy (AFM) has gained popularity in recent years [26]. High spatial resolution and three-dimensional  
Figure 4: Comparison of RMS among test groups. Figure 5: Comparison of surface roughness (Ra) among test groups. surface topography of specimens can be achieved with AFM. It is a highly sensitive and reliable technique that offers a suitable means of obtaining qualitative and quantitative information regarding the surface-related properties of rotary NiTi files [27]. Canal preparation is one of the most critical steps in root canal treatment since it determines the outcome of the endodontic treatment. NiTi instruments come in contact with the irrigants during chemo-mechanical preparations. During root canal treatment, mechanical friction or chemical stimuli cause loss of surface structure of the files used thus leads to wear and micro-crack formation [28; 29; 30]. Moreover, composition and manufacturing variations also account for the topographic variability of the NiTi rotary files. In a study by [PERSON] et al., [31] fatigue resistance and number of cycles before fracture for rotary instruments and relation to surface roughness were observed. It was concluded that the smaller the groove depth on the rotary instrument surface, the greater the number of fatigue cycles before fracture of the instrument. However, it was also shown in a previous study that the use of EDTA irrigant did not affect the cyclic fatigue resistance of the NiTi-tested files when used alone or in combination with other irrigants [32]. In the present study, two root canal irrigants, i.e., ethanolic extract of _S. mukorossi_ and 17% EDTA solution were used as a root canal irrigant in order to assess their effect on the surface characteristics of ProTaper Gold files with the help of AFM. It was found that there is an increase in Ra and RMS values of ProTaper Gold files after irrigating canals with both the irrigants compared to the unused files used as a control (_p_ < 0.05). These findings are in line with the findings of the study conducted by [PERSON] et al., [12]. They assessed the effect of 17% EDTA and 5% NaOCl on iRaCe and ProTaper NiTi instruments and observed that both the irrigants significantly increased the Ra values as compared to untreated files. The authors predicted that the surface irregularities formed during the manufacturing process of NiTi rotary files makes them prone to corrosion and surface changes [12]. In the present study, we also compared the Ra and RMS of both the irrigation groups and discovered that the mean Ra and RMS in the EDTA group were considerably greater than in the _S. mukorossi_ group. Similar findings were observed in the study by [PERSON] et al., which evaluated the effect of herbal irrigants, i.e., Triphala, EDTA, and NaOCl, on the structure of ProTaper rotary files [12]. In the study by [PERSON] et al., Triphala-irrigated ProTaper files had lower values of Ra and RMS compared to EDTA treated files [12]. Furthermore, unused files had lower values of Ra and RMS than Triphala-irrigated files [12]. Moreover, a study conducted by [PERSON] et al.