Comparative Evaluation of Preflaring Versus Non-Preflaring on the Accuracy of Electronic Apex Locators-a Systematic Review.

Dr. Ankita Nagrani*¹, Dr. Anita Sanap¹, Dr. Sourabh Mategaonkar², Dr. Shruti Khade^1, Dr. Karishma Krishnakumar¹
 

1. Conservative Dentistry and Endodontics, Dr. D. Y Patil Dental College, D.Y Patil Vidyapeeth, Pimpri, Pune.

2. Daswani dental college and research center Kota

*Corresponding Author: Dr. Ankita S. Nagrani, M.D.S, Conservative Dentistry and Endodontics, Dr. D.Y Patil Dental College, D.Y Patil Vidyapeeth, Pimpri, Pune

 
Received Date:  March 16, 2021

Publication Date: April 01, 2021

 

Abstract
 

INTRODUCTION: Success of endodontic treatment relies on the accurate determination of the working length and adequate enlargement of the root canal. Coronal preparing offers substantial advantages for more accurate apical sizing, with clinical implications regarding the adequacy of apical enlargement and debridement. Cervical preparation plays a vital role in reducing the discrepancy between initial apical file diameter and apical canal diameter.

Objective: The present review aims to assess the literature regarding preparing versus non-flaring of the root canal on the accuracy of apex locators in vitro experimental study.

MATERIALS AND METHODS:  MEDLINE, Google Scholar, and major journals were searched for studies from January 2007 to December 2017 to identify appropriate articles. A comprehensive search was designed, and the articles were independently screened for eligibility by two reviewers. In vitro studies done on human extracted teeth comparing preparing versus non-flaring on the accuracy of the apex, locators were considered.

Results: A total of 282 articles were searched out of which 19 articles were selected after reading the title and abstract. As a second step, full-text papers were obtained. Finally, a total of 9 articles were included after reading and evaluating full-text papers, out of which 1 article was excluded as it did not satisfy the inclusion criteria and 8 articles were selected for final synthesis.

CONCLUSION: Cervical preparation in root canals significantly increases the accuracy of apex locators.

Keywords: Cervical Preflaring, Accuracy Results: A total of 282 articles were searched out of which 19 articles were selected after reading the title and abstract. As a second step, full-text papers were obtained. Finally, a total of 9 articles were included after reading and evaluating full-text papers, out of which 1 article was excluded as it did not satisfy the inclusion criteria and 8 articles were selected for final synthesis.

Introduction

The most important step in endodontic treatment is the correct determination of working length as it prevents over-instrumentation and potential harm to the periapical region. (1) The apical constriction also referred to as the minor constriction diameter is an important anatomic landmark that is located at 0.5-1 mm from the major foramen and should be the point where instrumentation and obturation must terminate. (2) Radiographs and electronic apex locators are the tools available to determine the working length. With the evolution of Electronic Apex locators, determining working length has become more accurate and predictable. (2) Apex locators, currently, represent an important tool for the endodontist, because it enables with more practicality and precision the determination of the root canal’s working length, reducing the doubts regarding the exact location of the foramina ending. (3)

There are so many factors like the irregularity of walls /curvature of the root which affect initial working width determination. To minimize the influence of these affecting factors early coronal flaring is recommended. (4) Preflaring of the root canals is one of the important factors that may influence the accuracy of Electronic Apex Locators along with other factors like the size of the measuring file. (4) Flaring of the coronal third of root canals has been recommended by recent techniques. It has been suggested that coronal flaring contributes to successful performance in subsequent treatment processes, namely preparation, irrigation, and obturation.

Coronal flaring has also been shown to help determine the first file to bind at the WL and to establish the correct final diameter required for complete apical enlargement. (5,6) Files that are placed in pre-flared canals can easily reach the apical constriction and thus prevent a lower incidence of overextension than those placed in unflared canals. (8)

The increase in file size after preparation can be explained by realizing that, within a canal, irregularities and curvature produced contacts with the file and interfere with its progression toward the apex. Early flaring, regardless of the method used, removes these contacts, opens the space, and reduces file contact; thus, a file progresses more easily towards the apex after flaring.

This was previously suggested by Leeb. (9) Moreover, cervical preparation enhances the range of action of irrigating solution by enabling the advancement of the irrigation needle and penetration of the ultrasonic tip during passive ultrasonic irrigation (PUI). (10) Also, opening the coronal part of the canal early in the preparation may increase instrumentation efficiency, reduce canal instrumentation time and operator fatigue. (11)

Lack of patency and accumulation of debris in canals have been reported as impediments for the establishment of accurate working lengths. Stabholtz et al. analyzed the effect that preparing of canals might have on the tactile sensitivity of operators who attempted to manually locate the apical constriction, and the preparing of canals to significantly enhance the tactile sensitivity of the investigators.

They observed that the greatest binding of files occurred in the coronal third of canals and that by enlarging the canal orifices and eliminating cervical interferences, files could be passed more easily to the apices of teeth. (12).

Ibarrola et al. conducted a study to assess whether canal preparing would improve the efficacy of EALs and found statistical differences between the means obtained in the two groups, with more consistent results associated with the pre-flared group. (13)

However, to the best of our knowledge, there is no systematic review comparing the effectiveness of preparing on the accuracy of electronic apex locators. So this systematic review aims to compare the effect of preparing versus non-flaring on the accuracy of electronic apex locators.

 

Focused Question

What is the effect of preflaring versus non-flaring on the accuracy of apex locators?

 

Objective

To assess the literature regarding preparing versus non-flaring of the root canal on the accuracy of apex locators in vitro experimental study.

 

METHODS

 Inclusion criteria

1) Articles in English or those having detailed summary in English

2) studies that were published in between 1st January 2007 to 31st December 2017

3) In vitro studies done on human extracted teeth, studies comparing preflaring versus non flaring on the accuracy of apex locators.

Exclusion criteria

1)Case reports, abstracts, letters to editors, editorials and in vivo studies.

2)Studies not having a separate group for unflared teeth were also excluded. 

The PICOS guidelines that were selected are

P-(PARTICIPANTS): Freshly extracted human teeth.

I-(INTERVENTION): Preflaring of root canals.

C-(COMPARISON): Unflared canals.

O-(OUTCOME): Accurate working length.

 

Information Sources

Two Internet sources of evidence were used in the search of appropriate papers satisfying the study purpose: The National Library of Medicine (MEDLINE PubMed), Google Scholar, EBSCO Host, and SCOPUS and manual search using DPU college library resources. All cross-reference lists of the selected studies were screened for additional papers that could meet the eligibility criteria of the study. The databases were searched up to and including December 2017 using the search strategy.

 

Search

The following databases were searched on PubMed (the limits were all full-text articles in English dated from 1st January 2007 to December 31st, 2017), EBSCO HOST, SCOPUS, and Google Scholar. For the electronic search strategy, the following terms were used as keywords in several combinations.

 

Study Selection Process

Preliminary screening consisted of a total of 281 articles out of which 18 articles were selected. The papers were screened independently by two reviewers. At first, the papers were screened by title and abstract. As a second step, full-text papers were obtained when they fulfilled the criteria of the study aim. Any disagreement between the two reviewers was resolved after additional discussion.

For full-text screening, the following criteria were taken into consideration: In-vitro studies done on human extracted teeth in which comparison between preparing and non-flaring on the accuracy of electronic apex locators was assessed.

Finally, a total of 8 articles were included out of which 8 articles were finally synthesized in this systematic review.

 

Data Collection Process

A standard pilot form in the excel sheet was initially used and then all those headings not applicable for review were removed. Data extraction was done for one article and this form was reviewed by an expert and finalized. This was followed by data extraction for all the articles.

 

Results

The results of the search strategy are presented in table 1. Figure 1 represents a flow chart of the systematic review process. Total 282 articles were searched out of which 19 articles were selected after reading the title and abstract. As a second step, full-text papers were obtained. However, some studies did not include a separate unflared group. Finally, a total of 9 articles were included out of which 1 article was excluded as it did not satisfy the inclusion criteria and 8 articles were selected for final synthesis. All included articles were summarized in table 2.

 

Discussion

Root canal treatment should be limited only to the root canal. The dentin-cementum junction is the terminal point of root canal preparation and obturation. The most common method used to measure the working length is radiography, but the level of precision depends on the recording technique. Several disadvantages of this technique include radiation exposure, a long work process, and it is less representative of the three-dimensional tooth structure.

Therefore, an electronic root canal length measurement device (ERCLMD) was developed to overcome the deficiencies of radiographic techniques. Another advantage of this device is that it is applicable during pregnancy, however, its use should be carefully considered in patients with pacemakers. The ERCLMD, or so-called apex locator, works by electrical conductivity. The tissue surrounding the apex is larger than the inside of the root canal, both in dry and wet conditions and is non-conductive.

Coronal preflaring provides many advantages during cleaning and shaping in root canal procedures. The study conducted by Stabholtz et al. showed that coronal preflaring increases the tactile sensitivity of the operator in determining the location of the apical constriction. It also showed that the largest resistance when inserting the file into the root canal is the first one-third of the coronal end of the canal. Coronal preflaring decreases file resistance, thus, it is easier to insert the file into the root canal toward the apex of the tooth.

Other advantages of performing root canal preparation with coronal preflaring include improved irrigation circulation within the root canal, reducing the risk of bacteria being pushed into the periapical tissue and decreasing the risk of debris and irrigation fluid extrusion during root canal preparation procedures, as well as reducing errors in determining the working length during root canal preparation. 4 Out of the 8 articles included in the study only 1 study concluded that cervical preflaring with Gates Glidden burs did not significantly influence the apical locator accuracy in determining the actual working length. 4 studies out of the 8 studies used Root ZX as their apex locator which is a third-generation apex locator and they concluded  Coronal pre-flaring improved the accuracy of electronic apex locators.

Studies conducted by Camargo E.J et al, Junior B.M et al,BM Guimaraes, R Suryantoro and  Fernanda Ullmann Lopez et al used S1 and SX Protapers for the coronal flaring and concluded that coronal preflaring significantly increased the accuracy of electronic apex locators. Two of the studies used Gates-Glidden drills and the study by João Marcelo da Silva Teixeira et al concluded that cervical preflaring with Gates Glidden burs did not significantly influence the apical locator accuracy in determining the actual working length.

Morgental  R.D et al (2011) 1 conducted a study to compare the accuracy of three electronic apex locators (Novapex, Mini Apex, and Propex II) and used LA Axxess burs for preparing and they concluded that the accuracy of electronic apex locators increased after coronal preparing.

 

LIMITATIONS

The limitation of this systematic review is that there is a lack of literature searched for systematic review and a lack in the literature searched other than electronic databases.

 

CONCLUSION

Root canal treatment should be limited only to the root canal. The dentin-cementum junction is the terminal point of root canal preparation and obturation. This systematic review presents the advantages of preparing for the accuracy of electronic apex locators. The coronal preparing procedure during endodontic treatment is important to remove cervical dentin interferences. It allows easier insertion of manual or rotary instruments into the apical portion of the root canals and avoids changes in the WL during the root canal preparation. Some studies evaluating the influence of the crown-down preparing of root canal through nickel-titanium rotary instruments verified that the readings did not seem to undergo the influence of the dentin layer reduction in the location of a point close to the apical constriction and resulted in more precise readings. However, the preparation performed by rotary files shows a more regular and uniform feature while the use of Gates Glidden burs may cause a greater flaring.

 

References

1.Renata Dornelles Morgental ,   Fabiana Vieira Vier-Pelisser , Simone Bonato Luisi, Deborah Meirelles Cogo , Patrícia Maria Poli Kopper. “Preflaring effects on the accuracy of three electronic apex locators”. Rev Odonto Cienc 2011;26(4):331-335.

2.Camargo EJ, Zapato RO, Mederios PL, Bramante CM, Bemardineli N, Garcia RB, de Moraes IG, Duarte MG. “Influence of preflaring on the accuracy of length determination with four electronic apex locators”. J Endod 2009 Sep;35(9):13002.doi:10.1016/j.joen.2009.05.030

3.Junior M, Camilo C, Junior G, Pecora J, Darmio M, Neto S. “Effect of pre-flaring and file size on the accuracy of two electronic apex locators”. J Appl Oral Sci, 2012 Sep-Oct; 20(5): 538–543.

4.R Suryantoro, R Meidyawati and E Suprastiwi . “The effect of coronal preflaring on the accuracy of two electronic apex locators”. J. Phys.2017.

5.Contreras MAL, Zinman EH, Kaplan SK. “Comparison of the first file that fits at the apex, before and after early flaring”. J Endod 2001;27:113-6.

6.Ibelli GS, Barroso JM, Capelli A, Spanó JCE, Pécora JD. “Influence of cervical preflaring on apical file size determination in maxillary lateral incisors”. Braz Dent J 2007;18:102-6.

7.Fernanda Ullmann Lopez ,Fernando Branco Barletta , Vânia Regina Camargo Fontanella,  Fabiana Soares Grecca. “Effect of endodontic preflaring on electronic determination of working length”. Rev Odonto Cienc 2011;26(2):161-164

8.Pecora JD, Capelli A, Guerisoli DM, Spanó JC, Estrela C. “Influence of cervical pre-flaring on apical file size determination”. Int Endod J. 2005;38:430–435.

9.Sharma S, Tyagi S, Sinha D,Singh U, Chandra P, Kaur P. “Influence of cervical preflaring using different rotary instruments on the accuracy of apical file size determination: A comparative in-vitro study”. J Cons Dentistry.2014;17(6): 575-578

10.Ferreira C, Gomes F, Ximenes J, Teixena M, Arruda J, Ribamar G, Herculano L. “Influence of reuse and cervical preflaring on the fracture strength of reciprocating instruments”. Eur J Dent. 2017 Jan-Mar; 11(1): 41–47.

11.B. V. Sreenivasa Murthy , John.V.George , Mukesh Kumar. “Influence of coronal preflaring using gates glidden and protaper instruments on the first apical file size determination - A comparative in vitro study”. Endodontology. 2008 June

12.Ibarrola J, Chapman B, Howard JH, Knowles KI, Ludlow MO. “Effect of preflaring on Root ZX apex locators”. J Endod 1999;25:625-6.

13. Stabholz A, Rotstein I, Torabinejad M. “Effect of preflaring on tactile detection of the apical constriction”. J Endod 1995;21:92-4.

14.João Marcelo da Silva Teixeira,Myrna Bastos Barcellos,Marco André de Berrêdo Pinho,Carlos Augusto de Melo Barbosa,Rivail Antônio Sérgio Fidel,Sandra Rivera Fidel. “Effectiveness of an electronic apex locator used after preflaring of cervical and middle third”. RSBO. 2012 Apr-Jun;9(2):158-62

15.Samadi Y, Harandi A, Soleymani A, Khafri S, Tavanafar S. “Evaluation of the accuracy of root zx and raypex®6 apex locators in endodontic treatment and retreatments: an Ex vivo study”. Caspian J Dent Res 2016; 5:21-8.

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Volume 2 Issue 4 April 2021

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