Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study

Abstract

Aim:The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal.Materials and Methods:Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third.Statistical Analysis Used:Chi-squared test was used.Results:The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument.Conclusion:Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used.

Analysis of working surface in new manual and rotary endodontic instruments (scanning electron microscopy)

“…cobalt) results in decreased temperature of transformation. Increase in annealing temperature increases the transformation temperature as well [18].…”

“…Design of endodontic instruments, their metallurgical characteristics and surface may complicate endodontic treatment in case the instrument deforms or fractures during use. It is proved that manufacture defects might cause fracture of new instruments even during their first clinical use [18].…”

“…design characteristics of such instruments. Difficulties during manufacture of rotary endodontic instruments and elimination of surface irregularities such as traces of milling and metal flash (especially on blades) which might compromise efficiency of instrument blade and potentially cause problems related to corrosion or fracture [18].…”

Sem analysis of working surface in new manual endodontic instruments

“…Design of endodontic instruments, their metallurgical characteristics and surface may complicate endodontic treatment in case instrument deforms or fractures during use. It is proven that manufacturing defects might cause fracture of new instruments even during their first clinical use [20]. During manufacturing process, working surface of instruments, especially its threads, might have residuals of metal strips and organic and non-organic debris which might have infective and non-specific irritating potential [21][22][23][24].…”

“…Fretting on working surface of an instrument during the manufacturing process was noticed in all tested hand stainless steel instruments. Conventional manufacture of instruments by twisting the wire (of quadrangular profile for K-type file and milling of circular profile for Hedstorm file) causes surface irregularities such as traces of milling and metal flash (especially on blades) which might compromise efficiency of instrument blade and potentially cause problems related to corrosion and fracture [20,25,26]. Clinical importance of fretting on instrument surface reflects in its easy screwing (due to friction that is present because of uneven surface) which as a consequence leads to greater incidence of fracture [27].…”