Comparative Analysis of Apical Root Crack Propagation after Root Canal Preparation at Different Instrumentation Lengths Using ProTaper Universal, ProTaper Next and ProTaper Gold Rotary Files: An In vitro Study

Comparative Evaluation of the Incidence of Dentin Microcracks Following Biomechanical Preparation Using Four Different Nickel-Titanium Rotary File Systems: An In Vitro Study

INTRODUCTION

Biomechanical preparation has gotten easier over time with the development of nickel-titanium (NiTi) rotary instruments. Despite their benefits, research has shown that these files frequently result in microcracks in the root canal dentin, which can fracture the roots. Such mishaps should be prevented, as they compromise the integrity of the root and reduce the long-term survival of endodontically treated teeth.

MATERIALS AND METHODS

This study was conducted at Government Dental College and Hospital, Patiala, Punjab, India. Eighty permanent mandibular premolar teeth were included. All the roots were inspected for any pre-existing cracks or craze lines under a stereomicroscope. The teeth were decoronated and then divided into four groups (n = 20): Group I: TruNatomy, Group II: Neoendo Flex, Group III: ProTaper Gold, and Group IV: 2Shape. The samples were instrumented according to the group to which they belonged. The roots were then sectioned horizontally at 3 mm and 6 mm from the apex and examined under a stereomicroscope at 40x for the presence of microcracks.

RESULTS

The data were analyzed using the IBM SPSS Statistics for Windows, version 26 (released 2019; IBM Corp., Armonk, New York, United States). A chi-square test was applied, and the level of significance was set at p < 0.05. The highest incidence of microcracks was associated with ProTaper Gold (65%), followed by Neoendo Flex (45%), TruNatomy (20%), and 2Shape (20%).

CONCLUSION

 All rotary instruments resulted in dentinal damage. ProTaper Gold exhibited the highest frequency of dentin cracks. TruNatomy and 2Shape exhibited satisfactory results with minimal crack formation.

Analysis of the depth of penetration of an epoxy resin-based sealer following a final rinse of irrigants and use of activation systems: An in vitro study

Objective

The objective of the study was to compare and evaluate the depth of penetration of an epoxy resin-based sealer following a final rinse of 17% ethylenediaminetetraacetic acid (EDTA) and 18% 1-hydroxyethylidene 1, 1-diphosphonate (HEDP), with diode laser and passive ultrasonic activation (PUI): an in vitro confocal laser scanning microscopy study.

Materials and Methods

Fifty-two extracted human mandibular premolar teeth with single root and single canal were selected. They were disinfected in 0.1% thymol solution, cleaned of calculus and soft tissues, and stored in 0.1% thymol solution till use. All teeth were radiographed and selected as per the inclusion and exclusion criteria. The teeth were decoronated using a diamond disk under copious water spray to acquire a standardized root length of 14 mm. Working length was established by inserting a size 10-K file into each root canal until it is visible at the apical foramen and by subtracting 1 mm from the recorded length. Instrumentation of the root canal was done till master apical file size of F3 using ProTaper universal, rotary instruments. The canals were irrigated with 2 mL of 3% sodium hypochlorite between successive files. Teeth were randomly divided into four subgroups n = 12 according to the intervention. Passive ultrasonic irrigation and diode laser were used to activate the irrigants. Final irrigation was performed with distilled water. These specimens were examined using confocal laser scanning microscope (OLYMPUS FLUOVIEW FV 3000) for dentinal tubule penetration of the sealer. Two-way ANOVA test and Tukey's multiple post hoc test were used for statistical analysis.

Results

Highly significant difference was seen between the groups with EDTA and HEDP, with HEDP demonstrating the highest penetration. Among the activation techniques used in this study, PUI showed the highest penetration of the sealer. The least penetration was seen with diode laser activation and EDTA.

Conclusions

The irrigation activation techniques significantly influence the penetration of sealer into root dentinal tubules. When penetration of sealer with different irrigation techniques and irrigants was evaluated, significant greater level of sealer penetration was attained with PUI activation of HEDP.

Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems

Context

There is a possibility of dentinal crack formation in primary teeth after root canal preparation using rotary files.

Aims

To evaluate and compare the effect of ProTaper-Gold and Kedo-S rotary files on crack formation after root canal preparation in primary molars.

Settings and design

A total of 120 freshly extracted mandibular primary molars (6-9 years) were randomly divided into three groups of 40 each: ProTaper-Gold, Kedo-S, and Hand H-files, respectively.

Materials and methods

The roots were covered with a snuggly fitting surgical glove and stabilized in the teeth slot of a silicone mold of mandibular mixed dentition. Dental casts were obtained in a mixture of plaster of paris and sawdust. A screw system was incorporated in the cast for stabilization of the cast into the phantom head. All the root canals were instrumented in a standard operating position till 1 mm short of the radiographic apex. All roots were then stained and sectioned perpendicular to the long axis at the furcation level and 2 mm below the furcation to obtain one section per tooth. Sections were examined under a stereomicroscope at 25× magnification for any crack formations and recorded. Data were analyzed using Wilcoxon signed-rank and Kruskal-Wallis tests (p = 0.05).

Results

The total number of cracks in terms of percentage following the use of ProTaper Gold, Kedo-S, and H-files were 35, 10, and 0%, respectively, on the upper surface and 15, 5, and 0% on the lower surface. Within the group, there was a statistically significant difference in ProTaper-Gold (p = 0.001).

Conclusion

The use of ProTaper-Gold resulted in a greater number of dentinal cracks compared to Kedo-S and H-files.

How to cite this article

Patil MB, Mandroli PS, Jalannavar P, et al. Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems. Int J Clin Pediatr Dent 2023;16(5):692-697.

Oval Root Canals Prepared With Two Different Endodontic Rotary Files: An In Vitro Study Comparing the Incidence of Dental Defects

OBJECTIVE

This study aims to investigate and compare the establishment of dentinal cracks during root canal preparation using a stereomicroscope and a scanning electron microscope (SEM).

MATERIALS AND METHODS

Sixty removed human mandibular premolars were separated into three groups of 20: two experimental and one control. Within the randomized controlled experimental groups, root canals were constructed. Group I: the Waldent walflex file and Group II: the Trunatomy (TRN) file. Group III: the control group received no preparations. The surfaces of the roots were checked for dentinal cracks using a stereomicroscope and SEM following sectioning at 3, 6, and 9 mm from the apex. The Chi-square test was used to examine the data.

RESULTS

​​​​​​ In the control group, no fissures appeared. Cracks in Waldent Walflex were almost 66.7% between the 3mm and 6mm range. At both the 6 mm and 9 mm levels, there was no statistically significant difference between the experimental groups (P > 0.05). Defects were found to be substantially higher in the apical region of samples than in the median and coronal sections.

CONCLUSION

Dentinal fissures were created by every rotary file used in the tests. There were more flaws in the Waldent Walflex file group than in the Trunatomy file group.

Influence of Apical Diameter on Filling Material Extrusion during Retreatment - A Micro-CT and CBCT evaluation

AIM

To investigate whether foraminal widening performed at primary treatment has an effect on the amount of apically extruded obturator material during retreatment and to evaluate the sensitivity of cone beam computed tomography (CBCT) in detecting extruded obturator material.

METHODS

Forty palatal roots of maxillary molars were selected based on micro-CT and divided into two groups (n=20): with foraminal widening (WE) and without foraminal widening (NE). To standardize the apical foramen, all specimens were instrumented to the foramen using the Protaper Next system, up to instrument X3. The WE group was instrumented to the foramen up to instrument X5, and the NE group was instrumented 1 mm lower. The canals were obturated 1 mm below the apical foramen with gutta-percha and AH Plus and stored for 7 days at 37 °C and 95% humidity. Roots were fixed in microtubes filled with 1.5% agar gel. The obturation material was removed with Reciproc R50. Scans of the teeth and agar were performed using micro-CT and CBCT. Comparison between groups and between methods was performed using Mann-Withney test (p ≤0.05).

RESULTS

No statistical difference was found when comparing the extruded material between groups using micro-CT (p = 0.589) or CBCT (p = 0.953). CBCT measured a greater volume of extruded material than micro- CT (p = 0.0004).

CONCLUSION

Foraminal widening had no effect on the extrusion of filling material during retreatment. The CBCT favored the evaluation of apically extruded filling material.

A critical analysis of research methods and experimental models to study dentinal microcracks

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

[Comparison of three rotary file systems for removal of Enterococcus faecalis from infected root canals]

OBJECTIVE

To compare the efficacy of a novel rotary file system (EZ Pass) with two well-established rotary file systems(ProTaper Gold and ProTaper Next)for removal of Enterococcus faecalis from infected root canals in extracted maxillary central incisors.

METHODS

Models of root canal infection with Enterococcus faecalis were constructed in 51 extracted singlerooted maxillary central incisors.One of the incisor model with infected root canal was demineralized, sectioned, and stained with Brown & Brenn technique for microscopic observation; The remaining 50 models were randomly divided into 5 groups(n=10) for treatment with EZ Pass, ProTaper Gold, ProTaper Next, 0.9% NaCl or 2% NaOCl.Samples were collected from the infected root canals before and after the treatments to assess the percent reduction and logarithmic reduction value of CFU in the root canals.

RESULTS

The incisors with root canal infection by Enterococcus faecalis showed obvious biofilms on the surface of the root canals and massive bacterial invasion deep into the dentinal tubules, with a maximum invasion depth of about 475 μm.The percent reduction of the CFU did not differ significantly after treatments with EZ Pass, ProTaper Gold, ProTaper Next and 2% NaOCl (P > 0.05), but all these treatments resulted in significantly greater reduction than 0.9% NaCl (P < 0.01).The logarithmic reduction of CFU were comparable after treatments with EZ Pass (1.47±0.12), ProTaper Gold (1.74±0.14) and ProTaper Next (1.63±0.17;P > 0.05).

CONCLUSION

EZ Pass can significantly reduce the bacterial load in infected root canals with an equivalent bacterial elimination capacity to ProTaper Gold and ProTaper Next.

Dentinal Microcrack Formation after Root Canal Instrumentation by XP-Endo Shaper and ProTaper Universal: A Microcomputed Tomography Evaluation

Aim

To evaluate dentinal microcrack formation on root canals instrumented, continuously in the body temperature, with XP-endo shaper (XPES) and ProTaper Universal (PTU), by means of microcomputed tomographic (micro-CT) analysis. Methodology. Nineteen mesial roots with two separate canals (Vertucci Type IV) of extracted mandibular molars were used in this study. The root canals (N = 38) were divided into 2 groups. Group 1 (n = 19): all MB canals were instrumented with XPES. Group 2 (n = 19): all ML canals were instrumented with PTU. All roots were scanned with micro-CT before and after instrumentation. Two precalibrated examiners evaluated the cross-sectional images of each sample with DataViewer program. The dentinal microcracks (complete and incomplete) were counted in each third of the root for the preinstrumentation and the postinstrumentation images. Wilcoxin signed-rank and Mann–Whitney U tests were used for statistical analysis at a significance level of P < 0.05.

Results

The number of microcracks increased significantly (P < 0.05) after instrumentation with XPES in the middle and cervical thirds. The number of microcracks increased significantly (P < 0.05) after instrumentation with PTU in the cervical third only. There was no significant difference between the groups in the cervical and apical thirds. In the middle third, the XPES induced more incomplete microcracks than PTU (P < 0.05).

Conclusion

Within the limitations of this study, there was no significant difference in the dentinal microcrack formation between XPES and PTU in the apical and cervical thirds of the root. However, XPES instrumentation induced more incomplete microcracks than PTU in the middle third of human roots.