Introduction: The aim of this study was to investigate the fraction rate of Pro Taper Universal and Neoniti rotary files during the preparation of simulated severely-curved root canals.Materials & Methods: A total of 70 resin blocks with simulated severely-curved canals were randomly divided into two groups and prepared with Pro Taper Universal and Neoniti files. Each set of files was used for cleaning and shaping five canals; the files were sterilized after each application. Afterwards, the number of deformed and fractured files was recorded.Results: Deformation was reported in 11.4% and 19% of Pro Taper and Neoniti files, respectively (P>0.05). Also, fraction was found in 11.4% of Pro Taper files, while no fracture was reported in the Neoniti group; overall, no statistically significant difference was found between the groups (P>0.05).Conclusion: Based on the present findings, there was no significant difference between Pro Taper Universal and Neoniti files with respect to the incidence of deformation or fracture during the preparation of severely-curved canals.

Objectives During root canal preparation, dentinal chips, irrigants, and pulp remnants are extruded into the pre-radicular space. This phenomenon may lead to post-endodontic flare-ups. Furthermore, different preparation systems may be associated with varying amounts of apically extruded debris. This study aimed to compare the amount of debris extrusion using two endodontic preparation systems: ProTaper Universal and SafeSiders. Methods In this in vitro study, 30 single-rooted human mandibular premolars with fully developed apices and curvatures of 0-10 degrees were randomly assigned to two groups (N=15). The root canals were prepared with the ProTaper Universal and the SafeSiders system according to the manufacturer’s instructions. Extruded debris was collected into pre-weighed tubes by washing the apical foramen area with 1cc of distilled water. After incubating tubes for ten days to evaporate the remaining irrigants, the amount of apically extruded debris was calculated by subtracting each tube's initial and final weight. Data were analyzed by Student t-test at P<0. 05. Results The mean values for the amount of apically extruded debris using ProTaper Universal and SafeSiders system were 0. 0018±0. 0004 g and 0. 0023±0. 0006 g, respectively. The two groups had a statistically significant difference regarding the amount of the apically extruded debris. The SafeSiders system caused significantly more debris extrusion than the ProTaper Universal system (p<0. 01). Conclusion Both the ProTaper Universal rotary system and the SafeSiders reciprocating system caused apical debris extrusion,However, ProTaper Universal was associated with less debris extrusion.

Introduction: This study aimed to compare the incidence of dentinal crack formation by instrumentation with ProTaper Universal system (rotary, multi-file system), SafeSider (reciprocation movement, multi-file system) and Neolix (rotary, single-file system). Methods and Materials: In this in vitro study, 60 freshly extracted mandibular first molars were randomly divided into three experimental groups (n=15) and a control group containing unprepared teeth (n=15). Instrumentation in different groups was accomplished using either ProTaper, Neolix or SafeSider systems up to 25/0. 08. The teeth were then sectioned at 3, 6 and 9 mm from the apex, and observed under a stereomicroscope for presence of dentinal cracks. Data were analyzed with Chi square test, Fisher’ s exact test and Bonferroni correction. Results: Micro cracks were seen in all experimental groups (13. 3% in ProTaper, 26. 7% in SafeSider and 40% in Neolix). There was a significant difference between Neolix and the control groups in microcrack formation (P=0. 042). Micro cracks mainly occurred in the coronal section (9 mm). No microcrack occurred in the control group. Conclusion: Neolix rotary single-file system caused more dentinal cracks compared to the unprepared roots. All the instrumentation systems increased the number of micro cracks compared to unprepared teeth.

Statement of the Problem: Root canal preparation with rotary files causes dentinal cracks in root canals of primary teeth affecting their longevity.Purpose: Nickel-titanium rotary files have been widely used for root canal preparation in primary teeth. The present study compared occurrence of dentinal microcracks in root canals of extracted primary molar teeth prepared using Hedstrom (H) files, ProTaper Universal rotary files, and ProTaper Next rotary file systems.Materials and Method: In this in vitro experimental study, 80 primary molar mesial root canals were randomly divided into four groups of 20 canals each (n=20). Group I was prepared with H files. Group II was prepared with ProTaper Universal rotary files using shaping files SX and S2. Group III was instrumented with ProTaper Next rotary files X1 and X2 while Group IV was left unprepared and served as control. Roots were stained with 1% methylene blue solution and sectioned perpendicular to the long axis at 2mm, 4mm, and 6mm from the apical foramen. Slices obtained were examined under the stereomicroscope. Data obtained were subjected to statistical analysis using chi square tests.Results: Dentinal microcracks were observed in groups prepared using H files, ProTaper Universal, and ProTaper Next rotary files. Highest percentage of cracked root canals (20%) was seen in Group I, prepared by H files. These cracks were complete in nature, found in apical sections and statistically significant (p= 0.016). Group III prepared with ProTaper Next showed 10% dentinal cracks, followed by ProTaper Universal group with 5% cracked root canals.Conclusion: H files may be considered more aggressive at apical third due to complete cracks produced.

Background. The main goal of our study was to assess the volume of dentin removed and transportation in root canals using ProTaper Universal (PTU), ProTaper Gold (PTG) and One-Curve (OC). Ni-Ti rotary instruments in extracted human teeth using by micro-CT. Methods: Thirty human upper 1st premolar teeth with two separate root canals and sturdy, mature root tips were used in the present study. Specimens were decoronated and root length was standardized for micro CT scanning before root canal preparation done. The teeth were randomly separated into three categories (n = 10) according to the rotary NiTi system used for canal instrumentation, i. e., PTU (Dentsply, Maillefer), PTG (Dentsply, Maillefer), and OC (Micro-Mega SA). After root canal preparation, samples were scanned again on micro-CT by the same scanning parameters. Surface area, canal volume, structure model index (SMI), percentage of uninstrumented area and transportation parameters were obtained for each sample before and after micro-CT analyse. Results: No significant differences between the PTG and PTU in terms of the total volume of removed dentin, surface area and percentage of uninstrumented areas were found. However, regarding to parameters above, OC showed a lower efficacy than PTG and PTU in coronal section. Regarding canal transportation, PTG and OC showed lower mean transportation values at all levels. Conclusion: This paper demonstrated the root canal shaping abilities of the PTU, PTG, and OC NiTi file systems. The PTG and OC systems were associated less canal transportation and a better ability to preserve dentinal walls than PTU. There was no significance different between all rotary file systems for SMI values however, PTU and PTG showed greater canal volume and surface area change than OC file systems in coronal section.

Introduction: As a consequence of root canal preparation, dentinal chips, irrigants and pulp remnants are extruded into preradicular space. This phenomenon may lead to post endodontic flare-ups. The purpose of this study was to compare the amount of extruded debris with four endodontic NiTi enginedriven systems.Methods and Materials: Sixty mesiobuccal roots of maxillary molars with 15-30° curvature were divided randomly into four groups (n=15). Each group was instrumented up to apical size of 25 using Reciproc, Pro Taper Universal, Neolix and Hyflex. Bidistilled water was used as irrigant and extruded debris was collected in pre-weighted Eppendorf tubes. Tubes were stored in incubator for drying the debris. Extruded debris were weighted in electronic microbalance with accuracy of 0.0001 g. The raw data was analyzed with one way analysis of variance (ANOVA) and Tukey’s HSD post hoc test. Level of significance was set at 0.05.Results: The debris extrusion with Reciproc files was significantly higher than the other groups (P<0.05).Hyflex significantly extruded less debris than other files (P<0.05). There was no significant difference between Pro Taper Universal and Neolix regarding the amount of extruded debris (P=0.98).Conclusion: All systems extruded debris during the instrumentation. Reciproc system significantly extruded more debris. Caution should be taken when interpreting the results of this study and applying it to the real clinical situation.

Introduction: This study was conducted to compare three rotary files of Superfile III Denco, Sp1 Gold v taper, and ProTaper in terms of debris extrusion to find the best treatment option. Methods: In total, 51 extracted mandibular premolars were randomly assigned to three groups (n=17). Rotary systems of Sp1 Gold v taper, Superfile III Denco, and ProTaper Universal were used in the first, second, and third groups, respectively. Canals were prepared up to the F2 file, and this process was conducted only by one operator. Moreover, an Orifice shaper specific to each group was used first, and files were removed from canals and then cleaned by wet gauze. In the preparation procedure, canals were washed to extract all debris from the canal. Eppendorf tubes were used to collect debris. Results: Mean debris values extruded from canals in the Sp1 gold, Superfile Denco, and ProTaper Universal files were 0. 0025, 0. 0008, and 0. 0014, respectively. There was no significant difference among debris extruded by Superfile Denco III, SP1 gold V taper, and ProTaper Universal files (P<0. 05). Conclusions: All instrumentation systems cause the extrusion of debris to the apical area. According to the results of the present study, there was no significant difference among debris extruded by Superfile Denco, SP1 Gold, and ProTaper Universal files. It should be mentioned that because of variations in the study designs, the direct comparison of different studies that addressed this problem is not possible, and in vivo studies should be performed to evaluate its clinical relevance.