Microscopic Evaluation of Dentinal Defects after Root Canal Preparation with Different Hand and Nickel-Titanium Files; An In Vitro Study

Background

Effective endodontic instrumentation aims to remove microorganisms, debris, and tissue from the root canal while maintaining dentinal integrity. This study compares dentinal defect incidence following canal preparation with different hand files, nickel-titanium rotary files, and reciprocating files.

Materials and Methods

Eighty single-rooted mandibular premolars with mature apices were collected. Four groups (n = 20) were established based on canal patency establishment, canal preparation technique, irrigation solution, and final irrigation. After root sectioning at 3 mm, 6 mm, and 9 mm from the apex, slices were examined under a stereomicroscope, and dentinal defects were recorded. A second examiner reviewed the images.

Results

The results showed significant difference of P = 0.031 among Hand files vs. Rotary ProTaper files: In Hand files vs. Reciprocating WaveOne files significant difference was P = 0.048, and for rotary ProTaper files vs. Reciprocating WaveOne files: No significant difference (P = 0.643). Dentinal defect counts were similar at 3 mm, 6 mm, and 9 mm. Statistically significant variation was observed between hand files and rotary files, as well as hand files and reciprocating files.

Conclusion

Both rotary and reciprocating files showed a statistically significant increase in dentinal defect incidence compared to hand files. However, clinical implications should be considered cautiously. Instrumentation technique selection should be based on clinical context, operator experience, and patient factors. Further clinical studies are needed for validation.

Surface roughness and cyclic fatigue resistance of reciprocating and novel rotary instruments after use in curved root canals

This study evaluated surface wear and resistance to fracture of reciprocating and novel rotary instruments after use in curved canals. Twenty new instruments (n = 5/each group): Reciproc Blue, WaveOne Gold, XP-endo Shaper (XPS) and TruNatomy were used twice for the instrumentation of simulated curved canals in plastic blocks. The instrumentation was performed according to the manufacturer's instructions at body temperature. Surface roughness was evaluated, using a profilometer, before instrumentation and twice after the instrumentation. Instruments were, then, subjected to a cyclic fatigue test to evaluate the time to failure. Differences were assessed using ANOVA and post hoc tests (α = 0.05). The XPS instruments showed significantly higher values of roughness compared with TruNatomy at every stage, especially after the second use (p < 0.008). Reciprocating instruments showed superior cyclic fatigue resistance compared with novel rotary instruments (p < 0.05). TruNatomy showed minimal surface roughness, and XPS exhibited significantly higher surface roughness.

Detection of Dentinal Microcracks in Radicular Dentin after Shaping with XP-endo Shaper, Neoendo Flex Files, and Hero Shaper Using Scanning Electron Microscope: An In Vitro Study

The study aimed to compare the extent of dentinal microcracks in the radicular dentin using hand K files and various types of rotary nickel-titanium (NiTi) file systems. Forty mandibular incisor teeth (human) were grouped for the study. The root apices were closed, and the canals were straight (<5°). The samples were divided into four groups (n = 10). Group 1-Hand K file system (SybronEndo, SA), Group 2-XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland), Groups 3-Neoendoflex file (Neoendo, Orikam, India), and Group 4-Hero Shaper files (Micro-Mega, Becacon, France). Sectioning was done at 3, 6, and 9 mm from the apex, perpendicular to the long axis using a diamond disc under water coolant. The cut samples were then observed through a scanning electron microscope at ×50 enlargement. The control group showed no microcracks except one sample in the coronal third, which was less significant. The difference in the amount of crack detected on comparing the different groups was significant. In the experimental groups, XP-endo Shaper group showed significantly less number of cracks than the Neoendo flex, and Hero Shaper groups. Within the limitations of this study, all the system, except hand K files, produced remarkable dentinal microcracks. Least cracks were seen in canals instrumented with XP-endo Shaper. It can also be noted that single file system causes less number of microcracks.

Radiographic technical quality of root canal treatment performed by a new rotary single-file system

AIM

The aim of the present study was to evaluate radiographically the technical quality of root canal filling performed by postgraduate students with a new single-file Nickel-Titanium System (F6 Skytaper Komet) in clinical practice.

METHODS

Records of 74 patients who had received endodontic treatment by postgraduate students at the School of Dentistry, Faculty of Medicine, University of Pavia in the period between September 2015 and April 2016 were collected and examined: the final sample consisted 114 teeth and 204 root canals. The quality of endodontic treatment was evaluated by examining the length of the filling in relation to the radiographic apex, the density of the obturation according to the presence of voids and the taper of root canal filling. Chi-squared analysis was used to determine statistically significant differences between the technical quality of root fillings according to tooth's type, position and curvature.

RESULTS

The results showed that 75,49%, 82,84% and 90,69% of root filled canals had adequate length, density and taper respectively.

CONCLUSIONS

Overall, the technical quality of root canal fillings performed by postgraduates students was acceptable in 60,78% of the cases.

Comparative evaluation of the sealing ability of different obturation systems used over apically separated rotary nickel-titanium files: An in vitro study

Aim:

The study was designed to investigate the sealing ability of two obturation systems (cold laterally compacted gutta percha and Obtura II) over different apically separated rotary nickel-titanium files (RACE and K3 system) using dye extraction method.

Materials and Methods:

Sixty-two mandibular premolars were divided into 2 groups of 30 teeth each, and 2 teeth served as negative controls. In Groups A and B, roots were prepared using RACE and K3 system, respectively, and were further subdivided into 4 subgroups. In subgroups A1, B1 and A2, B2 (n = 10 each), files were separated at 3 mm from the tip in apical 3^rd of the canal. In subgroups A3, B3 and A4, B4 (n = 5), instruments were not separated. Subgroups A1, A3, B1, B3 and A2, A4, B2, B4 were obturated by lateral condensation method and Obtura II techniques, respectively. The sealing ability of the obturated specimens were tested using dye extraction method. The values for each group were recorded and analysis of variance (ANOVA), Student “t” test (two-tailed, independent), and Leven's test were performed.

Results:

Group A1 showed significantly less leakage than B1. No statistical significant difference between Groups A2 and B2 and Groups A3 and B3, respectively, were observed. Group A4 showed significantly less leakage than B4.

Conclusion:

Groups obturated with Obtura II showed less leakage than the lateral condensation technique irrespective of presence or absence of fractured NiTi rotary system.