Does the type of endodontic access influence in the cyclic fatigue resistance of reciprocating instruments?

Comparative evaluation of the remaining dentin volume following instrumentation with rotary, reciprocating, and hand files during root canal treatment in primary molars: An ex vivo study

Background/purpose

The effectiveness of root canal treatments with different file systems in primary teeth is important in terms of clinical practice and the use of file systems that work with different principles in primary tooth pulpectomy is becoming widespread. The amount of remaining dentin in the coronal region of the root is important in terms of the prognosis of the tooth and the long-term success of the treatment in teeth that have undergone root canal treatment. The aim of this study was to evaluate the remaining dentin volume in the coronal part of the root after the use of rotary, reciprocating, and conventional hand files in primary tooth pulpectomy.

Materials and methods

A total of 30 primary molars were divided into three groups. In each group, the preparations were made with three different file types: WaveOne Gold, which works with reciprocating motion; TruNatomy, which works with rotational motion; and conventional hand files. The three-dimensional images were evaluated for remaining dentin volume in the 2-mm coronal part of the root. Group means were compared using one-way analysis of variance, and post hoc analyses were performed with the Tukey test.

Results

There was no statistically significant difference between the groups in terms of preoperative and postoperative dentin volume (P > 0.05). The mean difference after preparation was observed the most in the WaveOne Gold group and the least in the TruNatomy group. When the mean percentage differences were evaluated, it was observed that statistically significantly more dentin volume was preserved after the preparation with TruNatomy than with WaveOne Gold (P = 0.021).

Conclusion

In primary tooth pulpectomy, file systems working with rotational motion can be preferred over file systems working with reciprocating motion in preserving the amount of dentin in the 2-mm coronal part of the root.

The influence of different root canal open access shapes on the use of rotary root canal enlargement

Background/purpose

The success of root canal treatments is influenced by the shape of the access opening and the outcomes of root canal enlargement. The aim of this study was to evaluate the impact of various rotary instruments on the maintenance of the root canal's central alignment post shaping, considering a range of access cavity designs.

Materials and methods

Using digital tooth simulation, 4 sets of 12 teeth underwent traditional (TradAC) or conservative (ConsAC) access cavity preparations. Root canals were enlarged with TruNatomy or ProTaper Ultimate rotary instruments. Canal transportation and centering ratio were separately measured. Statistical analysis was performed using JMP trial 17 software.

Results

The analysis revealed no significant difference in buccal and lingual canal transportation among different rotary instruments or canal enlargement designs (P > 0.05). TradAC yielded higher centering ratios in MB and ML canals, while ConsAC excelled in the distal canal for the TruNatomy group. Conversely, in the ProTaper Ultimate group, ConsAC demonstrated higher ML canal ratios (P < 0.05).

Conclusion

TruNatomy maintained superior canal centering with ConsAC, while ProTaper performed better with TradAC.

Impact of Pericervical Dentin on Fracture Resistance of Endodontically Treated Posterior Permanent Teeth: A Systematic Review and Meta-analysis

OBJECTIVE

The main aim of this present systematic review is to evaluate if the preservation of pericervical dentin (PCD) increases the fracture resistance of endodontically treated permanent posterior teeth.

MATERIALS AND METHODS

Two independent reviewers conducted a comprehensive review of all published studies from 2007 (1/1/2007) to 2023 (31/5/23) since the concept of PCD first appeared in the literature in 2007. Searches were conducted in multiple electronic database engines: PubMed, Scopus, EBSCO (Dentistry and oral health sciences), Web of Sciences (WOS), Cochrane, Google Scholar and Open Grey, Ovid and Shodhganga, in addition to cross-references and hand search. Articles were chosen according to a certain inclusion and exclusion criteria, which, in brief, are laboratory-based studies published in English that assess the impact of PCD on fracture resistance of endodontically treated permanent posterior teeth. Using domains, such as sample size, sample dimensions, and control group as quality assessment criteria, evaluated the selected articles and classified them according to their risk of bias into low, moderate, and high. A meta-analysis was conducted using random effects modeling at a significance level of p < 0.05.

RESULTS

A total of studies 6,043 were retrieved from 10 different electronic search databases and hand searches, but only 12 laboratory-based studies were selected after removing duplicates and applying the eligibility criteria. Of the included 12 studies, nine studies showed low risk of bias and three studies showed moderate risk of bias. Two studies showed related data for meta-analysis, the difference observed between the two studies is statistically non-significant.

CONCLUSION

Based on the results of the study, there is evidence to support that PCD preservation offers fracture resistance to the endodontically treated posterior teeth.

CLINICAL SIGNIFICANCE

The practice of conservative cavity preparation and avoiding the usage of instruments with high taper increases the fracture resistance of the tooth by retaining the PCD. How to cite this article: Haridoss S, Rajendran M, Swaminathan K, et al. Impact of Pericervical Dentin on Fracture Resistance of Endodontically Treated Posterior Permanent Teeth: A Systematic Review and Meta-analysis. J Contemp Dent Pract 2024;25(4):372-385.

Quantifiable design and comparative evaluation of straight-line minimally invasive endodontic cavity based on the anatomical features of the coronal part of root canal

Background/purpose

Minimally invasive endodontics has recently become popular in research. This study aimed to develop a new quantifiable straight-line minimally invasive endodontic cavity (SMIEC) for 3-rooted maxillary first molar based on the anatomical features of the coronal part of root canal.

Materials and methods

Cone-beam computed tomography (CBCT) images of 80 teeth were converted into models in Mimics Research software. Anatomical features of the coronal part of root canal were measured to develop SMIECs with straight-line accesses to root canals in 3-matic Research software. Twenty models were randomly sampled and each was duplicated for 8 simulation groups: non-treated (NT), traditional endodontic cavity (TEC), ninja endodontic cavity (NEC) and 5 SMIECs. Post-simulation models were subjected to finite element analysis to detect von-Mises stresses in ABAQUS software.

Results

Distributions of straight-line accesses to protogenetic root canals had certain manners, hence we developed 5 SMIECs. NEC and SMIECs had less hard tissue loss than TEC and presented different numerical rankings in different structures (P < 0.05). NEC had a less narrow surgery field than SMIECs except SMIEC2/4 (P < 0.05). The peak pericervical stresses of SMIECs were similar, lower than TEC and higher than NEC and NT (P < 0.05). The stress distributions of the 8 groups had certain manners.

Conclusion

Five SMIECs with straight-line accesses to root canals were developed, whose biomechanical properties were worse than NEC but better than TEC. Having appropriate structure preservation and surgery field, SMIEC2/4 was a preferred SMIEC.

Present status and future directions - Minimal endodontic access cavities

In the last decades, the move of Medicine towards minimally invasive treatments is notorious and scientifically grounded. As Dentistry naturally follows its footsteps, minimal access preparation also became a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue, backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key-points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection, and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make it clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach like minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws, but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in-situ laboratory model or a large and well-controlled clinical trial to solve this matter.

Current strategies for conservative endodontic access cavity preparation techniques-systematic review, meta-analysis, and decision-making protocol

OBJECTIVES

To assess related studies and discuss the clinical implications of endodontic access cavity (AC) designs.

MATERIALS AND METHODS

A systematic review of studies comparing the fracture resistance and/or endodontic outcomes between different AC designs was conducted in two electronic search databases (PubMed and Web of Science) following the PRISMA guidelines. Study selection, data extraction, and quality assessment were performed. Meta-analyses were undertaken for fracture resistance and root canal detection, with the level of significance set at 0.05 (P = 0.05).

RESULTS

A total of 33 articles were included in this systematic review. The global evaluation of the risk of bias in the included studies was assessed as moderate, and the level of evidence was rated as low. Four types of AC designs were categorized: traditional (TradAC), conservative (ConsAC), ultraconservative (UltraAC), and truss (TrussAC). Their impact on fracture resistance, cleaning/disinfection, procedural errors, root canal detection, treatment time, apical debris extrusion, and root canal filling was discussed. Meta-analysis showed that compared to TradAC, (i) there is a significant higher fracture resistance of teeth with ConsAC, TrussAC, or ConsAC/TrussAC when all marginal ridges are preserved (P < 0.05), (ii) there is no significant effect of the type of AC on the fracture resistance of teeth when one or two marginal ridges are lost (P > 0.05), and (iii) there is a significantly higher risk of undetected canals with ConsAC if not assisted by dental operating microscope and ultrasonic troughing (P < 0.05).

CONCLUSIONS

Decreasing the AC extent does not necessarily present mechanical and biological advantages especially when one or more surfaces of the tooth structure are lost. To date, the evidence available does not support the application of TrussAC. UltraAC might be applied in limited occasions.

CLINICAL RELEVANCE

Maintaining the extent of AC design as small as practical without jeopardizing the root canal treatment quality remains a pragmatic recommendation. Different criteria can guide the practitioner for the optimal extent of AC outline form which varies from case to case.

Influence of conservative endodontic access cavities on instrumentation of oval-shaped straight root canals

AIM

To evaluate the influence of the design of endodontic access cavities on the percentage of unprepared areas of canal walls and flexural fatigue of instruments activated by reciprocating movement in oval-shaped straight root canals of extracted teeth.

METHODOLOGY

Forty-two mandibular incisors with oval canals were scanned by a microcomputed tomography (micro-CT) device for homogeneous selection and distribution of the samples. Then, the teeth were divided into two groups (n = 21) according to the design of access cavity being tested: ultraconservative endodontic access cavity (UltraAC) and traditional access cavity. The canals were accessed with the aid of a surgical microscope, instrumented with the WaveOne Gold Medium system and irrigated with 2.5% NaOCl and 17% EDTA. The unprepared areas of the canal wall were analysed by overlaying images before and after instrumentation and expressed as percentages. micro-CT data were analysed using t-test, Mann-Whitney and Wilcoxon tests. The endodontic instruments used during instrumentation were subjected to static flexural fatigue testing using an artificial stainless steel canal with a 60° angle of curvature and a radius of 5 mm, located 5 mm from the tip of the instrument. The instruments were activated until fracture occurred, and the time in seconds for the fracture was recorded using a digital timer. The number of cycles to fracture was calculated and analysed statistically. For flexural fatigue data, an anova test complemented by a Tukey range test was used. The significance level of 5% was used for all analyses.

RESULTS

There was no significant difference between the groups related to unprepared areas by the instrument during canal preparation (p > .05). The difference in flexural fatigue resistance between the groups was not significant.

CONCLUSION

The use of UltraAC did not interfere with the canal instrumentation of extracted mandibular incisors with straight and oval canals. There was no difference in the flexural fatigue resistance of the instruments in relation to access cavity design.

Ten years of minimally invasive access cavities in Endodontics: a bibliometric analysis of the 25 most-cited studies

Objectives

This study aimed to analyze the main features of the 25 most-cited articles in minimally invasive access cavities.

Materials and Methods

An electronic search was conducted on the Clarivate Analytics' Web of Science ‘All Databases’ to identify the most-cited articles related to this topic. Citation counts were cross-matched with data from Elsevier's Scopus and Google Scholar. Information about authors, contributing institutions and countries, year and journal of publication, study design and topic, access cavity, and keywords were analyzed.

Results

The top 25 most-cited articles received a total of 572 (Web of Science), 1,160 (Google Scholar) and 631 (Scopus) citations. It was observed a positive significant association between the number of citations and age of publication (r = 0.6907, p < 0.0001); however, there was no significant association regarding citation density and age of publication (r = −0.2631, p = 0.2038). The Journal of Endodontics made the highest contribution (n = 15, 60%). The United States had the largest number of publications (n = 7) followed by Brazil (n = 4), with the most contributions from the University of Tennessee and Grande Rio University (n = 3), respectively. The highest number of most-cited articles were ex vivo studies (n = 16), and ‘fracture resistance’ was the major topic studied (n = 10).

Conclusions

This study revealed a growing interest for researchers in the field of minimally invasive access cavities. Future trends are focused on the expansion of collaborative networks and the conduction of laboratory studies on under-investigated parameters.