Penetration Depth of 5.25% Sodium Hypochlorite Solution Using Different Irrigation Needles and Activation Systems: An In Vitro Radiographic Assessment

INTRODUCTION

The success rate of endodontic treatment has improved owing to the development of newer techniques and instruments.¹ The primary objective of endodontic treatment is to eliminate bacterial burden from the root canal system. Traditionally it is accomplished by a combination of instrumentation and irrigation. Irrigants aid in the dissolution of necrotic and vital pulpal tissues and thereby mechanically flush the debris out from the root canals.² Irrigants were commonly delivered using a syringe and needle which did not allow complete debridement of dentinal tubules. Greater proximity of irrigants to the apical areas using irrigant activation devices, such as passive ultrasonic devices promotes their effectiveness.³ Additionally, for the thorough removal of debris and endodontic bacteria, irrigation needle penetration closer to the apical zone of the root canal is crucial.⁴

Sodium hypochlorite (NaOCl) remains the irrigant of choice due to its antibacterial nature, dissolving both necrotic and organic matter within the root canal.¹ The Scientific Committee Consensus recommends a sodium hypochlorite concentration of 2.5–5.25%, which strikes a good compromise between disinfection and toxicity.⁵

Irrigant delivery by a syringe and a needle during root canal treatment dates back more than a century.⁶ These needles largely vary by whether or not they have an open or closed tip, as well as a number of outlets.

The side vented needles are modifications of the conventional needle which consist of the lateral slot that accounts for irrigant flow for appropriate debridement of canal walls and minimizes the build-up of higher-pressure during irrigation.⁷

The TruNatomy^TM irrigation needle rounds out the therapeutic process. An even distribution of irrigation solution across the canal is maintained by the back-to-back 2-side vent design, providing better control. The needle can bend and flex readily to follow the architecture of the root canal because of the flexible polypropylene material.

Refillment and fluid exchange takes place just beyond the tip of the irrigation needle during conventional needle irrigation. The so-called vapor lock effect, which is caused by the entrapment of air in any portion of the root canal, might limit the effectiveness of irrigation by preventing the replacement of irrigants. After mechanical instrumentation, various methods and irrigant delivery devices have been suggested to improve canal cleanliness and the effectiveness of chemical disinfection within the root canal system.⁸

Numerous methods have been developed to improve irrigation effectiveness with relation to the irrigant’s ability to properly remove smear layer and debris as well as the depth of penetration. To optimize the results of endodontic therapy, effective irrigant administration and the activation of the irrigation solution are necessary.

A well-fitting master gutta-percha (GP) cone is repeatedly inserted to the working length of an instrumented canal in manual dynamic activation (MDA) to create hydrodynamic displacement forces inside irrigants.⁹ Acoustic cavitation and flowing forces are produced by passive ultrasonic irrigation using freely oscillating files at ultrasonic frequencies (25–30 kHz).^9,10

The endo activator system (EA), Sonically driven irrigant activation system, (DENTSPLY Tulsa Dental Specialties, Tulsa, OK, USA) consists of a portable handpiece and three different sizes of disposable flexible polymer tips that spare the root dentin and were created to vigorously and safely energize the hydrodynamic phenomenon.^11,12

Studies using radiopaque dyes have been suggested to examine the root canal irrigants’ penetration depth.¹ The radiopaque contrast agent used in this study is omnipaque (Iohexol). The purpose of the study is to assess and compare, using radiographic examination, the depth of penetration of radiolabeled 5.25% sodium hypochlorite solution utilizing various irrigation needles and activation methods.

MATERIALS AND METHODS

Sixty permanent single-rooted mandibular premolars extracted for orthodontic treatment from the dental college and nearby private clinics were selected as samples. Teeth with root canal curvature >300 root canal-treated teeth, caries teeth, teeth with cracks, fractures, and hypoplastic teeth were excluded. The soft tissue residues on the surface of the extracted teeth were removed with a hand scaler, and the teeth were stored in distilled water. The samples were examined using a radiograph to identify any canal deviations and calcification of canals and such teeth were eliminated from the study sample.

The 60 samples were randomly divided into four groups (n = 15) based on the type of irrigation needle used and each group was further subdivided into 3 subgroups (n = 5) based on the irrigation activation technique. The crowns were decoronated to a length of 14 mm to maintain uniformity of root length and mounted on a wax block. The apical foramen of the roots was sealed using wax to simulate a closed system. Standard endodontic access cavity was prepared using endoaccess bur (Super Endo-Endo access bur #14) and the initial patency was established using #10 K files (Mani K files, 21 mm) to the working length (WL). The cleaning and shaping of the samples were performed using the step-back technique with the hand file system. The apical preparation was done till the #30 file size (Mani K files, 21 mm) and further step back was done up to the #45 K files for all the samples with intermittent saline irrigation to remove dentin debris.

RESULTS

The pairwise tests for needles (Table 1) suggest that there is a significant difference among all the needles except side vent (group II) and double side vent needles (group III). TruNatomy needles (group IV) showed more depth of penetration compared to other needles and conventional needles (group I) showed the least depth of penetration.

Among the activation system, (Table 2) there is a significant difference among all three systems. Endo activator (subgroup III) showed most superior result compared to MDA (subgroup I) and ultrasonic system (subgroup II).

DISCUSSION

Microorganisms and their products are crucial to the pathologic processes that occur in the pulp and periapical regions.¹⁹ The success of root canal therapy depends on the eradication of these microbes from the root canal system.²⁰ Root canal irrigants aid in removing the microorganisms and their by-products with the aid of sufficient activation systems.²¹ In recent years, a number of studies have examined the effectiveness of root canal irrigation, including the methods of irrigation, the placement, the type of the needle, and the movement of the irrigation needle as the syringe method has been chosen for irrigation and also the level of root canal preparation, the characteristics, and the flow pattern of irrigants, etc.^21–23

This study was conducted on mandibular premolars to evaluate the radiographic assessment of the penetration depth of irrigants and compare conventional irrigation needles, side vented needles, and TruNatomy needles using different activation systems. The irrigation needles used were conventional stainless steel beveled needles, single side-vented needle, double-side vented needles and soft polypropylene TruNatomy irrigation needles and activation systems include MDA, ultrasonic activations, and sonic activations.

Apical enlargement was done up to 30 size (2%) and step back done up to 45 size (2%). Minimal apical enlargement was done to conserve the tooth structure and limit extrusion of filling materials at the same time allowing for sufficient volume of irrigant.^24–26 Albrecht et al. concluded that root canal debridement is mainly affected by final instrument size and root canal taper contributes in debridement only when the final instrument size is smaller than 30.^27,28

Root canal preparation was standardized, and a 30-gauge needle was used to deliver a predetermined quantity of irrigants into the canal space since its outer diameter is 0.3 mm, which is equivalent to 30-size instruments.²⁹ The irrigation depth is also standardized and the needle depth should be 2 mm short of the apex which is in accordance with a study done by Shin et al.⁷

In this study, TruNatomy needles when used with all activation systems showed more depth of penetration compared to other needles. It is referred to as a comprehensive clinical solution since it was created to respect the genuine natural anatomy of the root canal. The flexible polypropylene irrigation needles allow the needle to curve and flex easily to follow the root canal anatomy. Irrigant confines in the root canal itself even in maxillary teeth by neglecting the effect of gravity.

Conventional needles showed the least depth of penetration regardless of the activation method, which is consistent with a study by Srivastava et al.³⁰ The jet in open-ended needles (flat, beveled, notched) is very strong, extends along the root canal, and breaks up gradually at the tip. Clinicians frequently use this needle to deliver irrigants in clinical settings. The apical portion of the root canal is where conventional irrigation methods perform less than the coronal aspect, according to different studies.^21,31

Side vent and double side vent needles showed no significant difference in depth of penetration among the various activation systems. When closed-ended needles with side or double vents are utilized, the jet forms close to the outlet’s apical side and is directed apically with a minor divergence.³² The major route taken by the irrigant is a curved one that rounds the tip before leading to the coronal orifice. There is twice as high maximum shear stress, but limited to near their tip, on the wall facing the needle outlet. Side vent needles mainly reduce the apical extrusion and at the same time improve the hydrodynamic activation of irrigants.¹³ According to Silva et al., the needles with two side vents produced the least material extrusion into the periapical tissues. These modified needle tips decreased the pressure that was created at the apical foramen, which may have lowered the likelihood that the irrigant would be extruded into the periapical tissues.³³

According to Schiavotelo, irrigant activation with sonic devices (EA-EDDY) outperformed previous irrigant activation protocols.³⁴ Similar to the previous study, the application of a sonic device (endo activator) demonstrated greater depth of penetration in comparison to MDA and ultrasonic activation. To increase the effectiveness of NaOCl, acoustic and ultrasonic instruments produce vibrations inside the root canal.³⁵ Among the different needle activations, the TruNatomy needle along with sonic activation showed greater depth of penetration.

Although radiographic contrast agents are frequently utilized in medicine, their application in dentistry has been relatively sparse.¹ Researchers have recently employed it in conjunction with radiography to assess and compare the penetration of the canal system. Iohehol (omnipaque), a low osmolar radiopaque contrast medium, is recommended for intrathecal administration in humans for many imaging procedures, including myelography, contrast augmentation for computed tomography, and imaging of the salivary glands. Omnipaque has a non-ionic, monomeric structure, excellent water solubility, and viscosity and density that are very similar to those of 5.25% NaOCl. These properties set it apart from other contrast agents.

Kodak Dental Imaging Software 5.200 and digital radiography with intraoral sensor were used to deliver quick results for each technique. At all stages of irrigation, radiographs were taken by maintaining a standard position for the fixation system, radiological tube, sensor, and samples. This prevented movements and limit radiographic errors while doing the evaluation.¹

CONCLUSION

Within the limitations of the study, the TruNatomy irrigation needle showed the most promising irrigation method when used in conjunction with Sonic activation. There was no difference in depth of penetration between side-vented and double-side-vented needles.

REFERENCES

1. Dhaimy S, Imdary S, Dhoum S, et al. Radiological evaluation of penetration of the irrigant according to three endodontic irrigation techniques. Int J Dent 2016;2016:1–6. DOI: 10.1155/2016/3142742.

2. Kandaswamy D, Venkateshbabu N. Root canal irrigants. J Conserv Dent 2010;13(4):256–264. DOI: 10.4103/0972-0707.73378.

3. Boutsioukis C, Arias-Moliz MT. Present status and future directions–irrigants and irrigation methods. Int Endod J 2022;55(Suppl 3):588–612. DOI: 10.1111/iej.13739.

4. GuLS, Kim JR, Ling J, et al. Review of contemporary irrigant agitation techniques and devices. J Endod 2009;35(6):791–804. DOI: 10.1016/j.joen.2009.03.010.

5. Kini S, Shetty SV, Shetty KH, et al. The efficiency of 2.5% sodium hypochlorite in preventing inoculation of periapical tissues with contaminated patency files: An ex vivo evaluation. J Pharm Bioallied Sci 2015;7(Suppl 2):S563–S566. DOI: 10.4103/0975-7406.163542.

6. Machtou P. Manual Dynamic Activation (MDA) Technique. In: Endodontic Irrigation. Cham: Springer International Publishing; 2015. pp. 149–55.

7. Shin SJ, Kim HK, Jung IY, et al. Comparison of the cleaning efficacy of a new apical negative pressure irrigating system with conventional irrigation needles in the root canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109(3):479–484. DOI: 10.1016/j.tripleo.2009.10.050.

8. Boutsioukis C, Kastrinakis E, Lambrianidis T, et al. Formation and removal of apical vapor lock during syringe irrigation: A combined experimental and computational fluid dynamics approach. Int Endod 2014;47(2):191–201. DOI: 10.1111/iej.12133.

9. Ada K, Shetty S, Jayalakshmi KB, et al. Influence of different irrigant activation methods on apical debris extrusion and bacterial elimination from infected root canals. J Conserv Dent 2023;26(1):31–35. DOI: 10.4103/jcd.jcd_378_22.

10. Van der Sluis LW, Versluis M, Wu MK, et al. Passive ultrasonic irrigation of the root canal: A review of the literature. International endodontic journal 2007;40(6):415–426. DOI: 10.1111/j.1365-2591.2007.01243.x.

11. Chaudhry S, Yadav S, Talwar S, et al. Effect of Endo Activator and Er, Cr: YSGG laser activation of Qmix, as final endodontic irrigant, on sealer penetration: A confocal microscopic study. J Clin Exp Dent 2017;9(2):e218–e222. DOI: 10.4317/jced.53270.

12. Mancini M, Cerroni L, Iorio L, et al. Smear layer removal and canal cleanliness using different irrigation systems (EndoActivator, EndoVac, and passive ultrasonic irrigation): Field emission scanning electron microscopic evaluation in an in vitro study. J Endod 2013;39(11):1456–1460. DOI: 10.1016/j.joen.2013.07.028.

13. Pasricha SK, Makkar S, Gupta P. Pressure alteration techniques in endodontics - A review of literature. J Clin Diagn Res 2015;9(3):ZE01–ZE06. DOI: 10.7860/JCDR/2015/9249.5613.

14. İnce-Yusufoğlu S, Keskin NB, Uslu G, et al. Effect of EDDY and manual dynamic activation techniques on postoperative pain in non-surgical retreatment: A randomized controlled trial. BMC Oral Health 2023;23(1):3. DOI: 10.1186/s12903-022-02702-4.

15. Plotino G, Pameijer CH, Grande NM, et al. Ultrasonics in endodontics: A review of the literature. J Endod 2007;33(2):81–95. DOI: 10.1016/j.joen.2006.10.008.

16. Boutsioukis C, Gogos C, Verhaagen B, et al. The effect of apical preparation size on irrigant flow in root canals evaluated using an unsteady Computational Fluid Dynamics model: CFD preparation size study. Int Endod J 2010;43(10):874–881. DOI: 10.1111/j.1365-2591.2010.01761.x.

17. Kharouf N, Pedullà E, La Rosa GRM, et al. In vitro evaluation of different irrigation protocols on intracanal smear layer removal in teeth with or without pre-endodontic proximal wall restoration. J Clin Med 2020;9(10):3325. DOI: 10.3390/jcm9103325.

18. Goel T, Saraf BG, Indushekar KR, et al. Comparative evaluation of working length using conventional radiographic method, radiovisiography, and apex locator in single-rooted permanent teeth. J Oral Health Community Dent 2021;15(2):49–54. DOI: https://doi.org/10.5005/jp-journals-10062-0103.

19. Bronzato JD, Bomfim RA, Hayasida GZP, et al. Analysis of microorganisms in periapical lesions: A systematic review and meta-analysis. Arch Oral Biol 2021;124:105055. DOI: 10.1016/j.archoralbio.2021.105055.

20. Narayanan LL, Vaishnavi C. Endodontic microbiology. J Conserv Dent 2010;13(4):233–239. DOI: 10.4103/0972-0707.73386.

21. Ali A, Bhosale A, Pawar S, et al. Current trends in root canal irrigation. Cureus 2022;14(5):e24833. DOI: 10.7759/cureus.24833.

22. Haapasalo M, Shen Y, Wang Z, et al. Irrigation in endodontics. Br Dent J 2014;216(6):299–303. DOI: 10.1038/sj.bdj.2014.204.

23. Teja KV, Ramesh S, Battineni G, et al. The effect of various in-vitro and ex-vivo parameters on irrigant flow and apical pressure using manual syringe needle irrigation: Systematic review. Saudi Dent J 2022;34(2):87–99. DOI: 10.1016/j.sdentj.2021.12.001.

24. Butcher S, Mansour A, Ibrahim M. Influence of apical preparation size on effective conventional irrigation in the apical third: A scanning electron microscopic study. Eur Endod J 2019;4(1):9–14. DOI: 10.14744/eej.2018.06078.

25. Akhlaghi NM, Dadresanfar B, Darmiani S, et al. Effect of master apical file size and taper on irrigation and cleaning of the apical third of curved canals. J Dent (Tehran) 2014;11(2):188–195. PMID: 24910695.

26. Brunson M, Heilborn C, Johnson DJ, et al. Effect of apical preparation size and preparation taper on irrigant volume delivered by using negative pressure irrigation system. J Endod 2010;36(4):721–724. DOI: 10.1016/j.joen.2009.11.028.

27. Albrecht LJ, Baumgartner JC, Marshall JG. Evaluation of apical debris removal using various sizes and tapers of ProFile GT files. J Endod 2004;30(6):425–428. DOI: 10.1097/00004770-200406000-00012.

28. Arvaniti IS, Khabbaz MG. Influence of root canal taper on its cleanliness: A scanning electron microscopic study. J Endod 2011;37(6):871–874. DOI: 10.1016/j.joen.2011.02.025.

29. Khademi A, Yazdizadeh M, Feizianfard M. Determination of the minimum instrumentation size for penetration of irrigants to the apical third of root canal systems. J Endod 2006;32(5):417–420. DOI: 10.1016/j.joen.2005.11.008.

30. Srivastava I, Srivastava S, Grover R, et al. Comparative evaluation of efficacy of different irrigating needles and devices in removal of debris from apical third of root canal: An in-vitro SEM study. Contemp Clin Dent 2021;12(3):222–229. DOI: 10.4103/ccd.ccd_468_20.

31. van der Sluis L, Boutsioukis C, Jiang LM, et al. Root Canal Irrigation. In: Springer Series on Biofilms. Berlin, Heidelberg: Springer Berlin Heidelberg; 2015. pp. 259–301. DOI: 10.1007/978-3-662-47415-0_9.

32. Bulgu S, Yıldızeli A, Çadırcı S, et al. Computational investigation of the tip effects of various root canal needles on irrigation performance. Essent Dent 2021;1(1):30–37. DOI: 10.5152/EssentDent.2021.21007.

33. Silva PB, Krolow AM, Pilownic KJ, et al. Apical extrusion of debris and irrigants using different irrigation needles. Braz Dent J 2016;27(2):192–195. DOI: 10.1590/0103-6440201600382.

34. Schiavotelo TCL, Coelho MS, Rasquin LC, et al. Ex-vivo smear layer removal efficacy of two activated irrigation techniques after reciprocating instrumentation in curved canals. Open Dent J 2017;11:512–519. DOI: 10.2174/1874210601711010512.

35. Mohammadi Z, Shalavi S, Giardino L, et al. Impact of ultrasonic activation on the effectiveness of sodium hypochlorite: A review. Iran Endod J 2015 Fall;10(4):216–220. DOI: 10.7508/iej.2015.04.001.