The comparative evaluation of the effects of hand and rotary instruments using various irrigation agents on smear layer removal in root canals of primary teeth: a scanning electron microscope study

Background: To assess the efficiency of various irrigation techniques employed for eliminating smear layer removal (SLR) in primary tooth root canals following the use of both rotary and hand instrumentation systems using scanning electron microscopy (SEM). Methods: 80 extracted maxillary primary incisors were randomly divided into two main groups: the Easy in Smile X Baby Rotary File Group (ESXF Group) (n = 40) and the K-type Hand File Group (K-File Group) (n = 40). Subsequently, the main groups were divided into four subgroups randomly: one treated with a 5% Ethylene Diamine Tetra Acetic Acid (EDTA) solution, another with 6% (Citric Acid) CA, a third with 1% (Sodium Hypochlorite) NaOCl, and a control group that received 0.9%(Physiological Saline) PS. Following the irrigation procedures, an SEM analysis was performed on three specific areas of the root canal: the coronal, middle, and apical. The data collected underwent statistical analysis using different tests like Friedman’s, Mann Whitney U, Kruskal Wallis, and Dunn’s, with a significance level of 5%. Results: In both instrumentation groups, EDTA and CA showed superior efficacy compared to the others on all root canal thirds (p < 0.05) and no difference was observed between EDTA and CA (p > 0.05). However, erosive defects were seen in both groups for EDTA, especially in coronal third, were not seen in CA subgroups. Also, all irrigants were less effective in apical third. There was also no statistical difference between ESXF and K-File groups for each irrigant (p > 0.05). Conclusions: Due to its comparable efficiency to 5% EDTA in terms of SLR and lack of erosive properties, 6% CA is a suitable choice for pulpectomy procedures in primary teeth when using rotary systems.

Rotary instrument systems; Irrigation solutions; Smear layer

[1] Demirel A, Yüksel BN, Ziya M, Gümüş H, Doğan S, Sari Ş. The effect of different irrigation protocols on smear layer removal in root canals of primary teeth: a SEM study. Acta Odontologica Scandinavica. 2019; 77: 380–385.

[2] Alaçam A. Endodontic approaches in pedodontics. In Alaçam T (ed.) Endodonti (pp. 1241–1302). Özyurt Matbaacılık: Ankara. 2012.

[3] Walsch H. The hybrid concept of nickel-titanium rotary instrumentation. Dental Clinics of North America. 2004; 48: 183–202.

[4] Demirel A, Sarı Ş. Primary teeth root canal treatment: why, when, how? Turkiye Klinikleri Pediatric Dentistry-Special Topics. 2017; 3: 99–112.

[5] Dummett CO, Kopel HM. Pediatric endodontics. In Ingle JI, Bakland LK (eds.) Endodontics (pp. 861–902). 5th edn. BC Decker Inc Hamilton: Ontario. 2002.

[6] Fumes AC, Sousa-Neto MD, Leoni GB, Versiani MA, da Silva LAB, da Silva RAB, et al. Root canal morphology of primary molars: a micro-computed tomography study. European Archives of Paediatric Dentistry. 2014; 15: 317–326.

[7] Jeevanandan G. Kedo-S paediatric rotary files for root canal preparation in primary teeth—case report. Journal of Clinical Diagnostic Research. 2017; 11: ZR03–ZR05.

[8] Schafer E, Lohmann D. Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile—Part 1. Shaping ability in simulated curved canals. International Endodontic Journal. 2002; 35: 505–513.

[9] Sen BH, Piskin B, Demirci T. Observation of bacteria and fungi in infected root canals and dentinal tubules by SEM. Dental Traumatology. 1995; 11: 6–9.

[10] Violich DR, Chandler NP. The smear layer in endodontics—a review. International Endodontic Journal. 2010; 43: 2–15.

[11] Arruda MPD, Carvalho Junior JRD, Miranda CES, Paschoalato C, Silva SRC. Cleaning of flattened root canals with different irrigating solutions and nickel-titanium rotary instrumentation. Brazilian Dental Journal. 2009; 20: 284–289.

[12] Darrag AM. Effectiveness of different final irrigation solutions on smear layer removal in intraradicular dentin. Tanta Dental Journal. 2014; 1: 93–99.

[13] Manjunatha M, Annapurna K, Sudhakar V, Sunil Kumar V, Hiremath VK, Shah A. Smear layer evaluation on root canal preparation with manual and rotary techniques using EDTA as an irrigant: a scanning electron microscopy study. Journal of International Oral Health. 2013; 5: 66–78.

[14] Prati C, Foschi F, Nucci C, Montebugnoli L, Marchionni S. Appearance of the root canal walls after preparation with NiTi rotary instruments: a comparative SEM investigation. Clinical Oral Investigations. 2004; 8: 102–110.

[15] Demirel A, Önder NS, Alkış M, Sarı Ş. Smear layer removal efficacy of irrigating solutions applied distinct needle designs: a scanning electron microscopy study. Journal of Clinical Pediatric Dentistry. 2023; 47: 58–66.

[16] Toyota Y, Yoshihara T, Hisada A, Yawaka Y. Removal of smear layer by various root canal irrigations in primary teeth. Pediatric Dentistry Journal. 2017; 27: 8–13.

[17] Vallabhaneni K, Kakarla P, Avula SSJ, Reddy NVG, Gowd MP, Vardhan KR. Comparative analyses of smear layer removal using four different irrigant solutions in the primary root canals—a scanning electron microscopic study. Journal of Clinical Diagnostic Research. 2017; 11: ZC64–ZC67.

[18] Haapasalo M. Can I use chlorhexidine as the only irrigating solution in my endodontic treatments? Journal of the Canadian Dental Association. 2011; 77: b16.

[19] Moskovitz M, Tickotsky N. Pulpectomy and root canal treatment (RCT) in primary teeth: techniques and materials. Pediatric Endodontics. 2016; 18: 71–101.

[20] Ramachandra JA, Nihal NK, Nagarathna C, Vora MS. Root canal irrigants in primary teeth. World Journal of Dentistry. 2015; 6: 229–234.

[21] Hülsmann M, Peters OA, Dummer PMH. Mechanical preparation of root canals: shaping goals, techniques and means. Endodontic Topics. 2005; 10: 30–76.

[22] Kaur R, Singh R, Sethi K, Garg S, Miglani S, Vats S. Irrigating solutions in pediatric dentistry: literature review and update. Journal of Advanced Medical and Dental Sciences Research. 2014; 2: 104–115.

[23] Pitoni CM, Figueiredo MC, Araújo FB, Souza MAL. Ethylenediaminetetraacetic acid and citric acid solutions for smear layer removal in primary tooth root canals. Journal of Dentistry for Children. 2011; 78: 131–137.

[24] Ximenes M, Triches TC, Beltrame AP, Hilgert LA, Cardoso M. Effect of endodontic irrigation with 1% sodium hypochlorite and 17% EDTA on primary teeth: a scanning electron microscope analysis. Journal of General Dentistry. 2013; 61: 24–27.

[25] Dadresanfar B, Khalilak Z, Delvarani A, Mehrvarzfar P, Vatanpour M, Pourassadollah M. Effect of ultrasonication with EDTA or MTAD on smear layer, debris and erosion scores. Journal of Oral Science. 2011; 53: 31–36.

[26] Demirel A. The smear layer removal efficiency of different concentrations of EDTA in primary teeth: a SEM study. Cumhuriyet Dental Journal. 2021; 24: 57–65.

[27] Barcelos R, Tannure PN, Gleiser R, Luiz RR, Primo LG. The influence of smear layer removal on primary tooth pulpectomy outcome: a 24‐month, double‐blind, randomized, and controlled clinical trial evaluation. International Journal of Paediatric Dentistry. 2012; 22: 369–381.

[28] Schäfer E, Vlassis M. Comparative investigation of two rotary nickel-titanium instruments: ProTaper versus RaCe. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth. International Endodontic Journal. 2004; 37: 239–248.

[29] Kramer WS IR. Measurements of the primary teeth. Journal of Dentistry for Children. 1959; 26: 252–261.

[30] Ignat L, Ignat M-E, Grădinaru I. Hydroxyapatite-supported silver nanoparticles and preliminary investigations of their catalytic potential. Revista de Chimie. 2017; 68: 1469–1472.

[31] Syed J. Scanning electron microscopy in oral research. Journal of Pakistan Dental Association. 2017; 26: 189–195.

[32] Hurjui I, Statescu C, Balcos C, Hurjui IA, Hartan RM, Martu MA, et al. Scannig electron microscopy a good choice for study dental hard tissue and biomaterial structure. Romanian Journal of Oral Rehabilitation. 2021; 13: 153–159.

[33] Sayid SA, Dadan-Garba A, Enenche DE, Ikyo BA. Scannig electron microscopy (SEM) of the bug eye and sand coral. Microscopy Research. 2020; 8: 1–7.

[34] Thompson SA. An overview of nickel-titanium alloys used in dentistry. International Endodontic Journal. 2000; 33: 297–310.

[35] Hariharan VS, Nandlal B, Srilatha KT. Efficacy of various root canal irrigants on removal of smear layer in the primary root canals after hand instrumentation: a scanning electron microscopy study. Journal of Indian Society of Pedodontics and Preventive Dentistry. 2010; 28: 271–277.

[36] Niu W, Yoshioka T, Kobayashi C, Suda H. A scanning electron microscopic study of dentinal erosion by final irrigation with EDTA and NaOCl solutions. International Endodontic Journal. 2002; 35: 934–939.

[37] Vallikanthan S, Reddy KB, Dash S, Kallepalli S, Chakrapani N, Kalepu V. A comparative evaluation of cleaning efficacy (debris and smear layer removal) of hand and two NiTi rotary instrumentation systems (K3 and ProTaper): a SEM study. The Journal of Contemporary Dental Practice. 2013; 14: 1028–1035.