eISSN: 2299-551X
ISSN: 0011-4553
Journal of Stomatology
Current issue Archive Manuscripts accepted About the journal Editorial board Reviewers Abstracting and indexing Subscription Contact Instructions for authors Ethical standards and procedures
SCImago Journal & Country Rank

vol. 75
Review paper

Causes of post-operative pain related to root canal treatment

Ewa Zawrzykraj
Wiktor Krużyński
Mateusz Radwański
Monika Łukomska-Szymańska

Multispecialist Dental Clinic, University Clinical Hospital WAM UM in Lodz, Lodz, Poland
Department of Endodontics, Medical University of Lodz, Lodz, Poland
Department of General Dentistry, Medical University of Lodz, Lodz, Poland
J Stoma 2022; 75, 3: 201-205
Online publish date: 2022/09/01
Article file
Get citation
JabRef, Mendeley
Papers, Reference Manager, RefWorks, Zotero


Root canal treatment (RCT) aims to prevent periapical tissue from pulp inflammatory process propa­gation and heal periapical lesions that already exist. It comprises disinfection of root canals by chemo-mechanical preparation and medicaments applied between visits. Post-operative pain related to RCT usually occurs in response to apical extrusion of debris (AED) or over-preparation of apical area [1, 2]. Other causes of post-operative pain include incomplete pulp removal, apical extrusion of obturating material, chemical irritation, root fracture, and improper adjustment of a filling [3].
AED is defined as periapical displacement of dentinal chips with micro-organisms, necrotic tissues, irrigation solution, and pulpal fragments [1, 4-6]. It contributes to symptomatic periodontitis resulting in early or late failure of endodontic treatment [4]. This phenomenon is related to the imbalance between root canal microbiota and host’s immune response, leading to episodes of acute periodontitis or exacerbation of chronic periodontitis [1, 6, 7]. Therefore, removal of debris is an essential condition for therapeutic success [8]. Gambarini et al. [6] reported that improper irrigation, over-instrumentation, and lack of recapitulation may result in an increase of AED. Type of tooth, structure of root canal system, working length (WL), instrumentation technique, foraminal enlargement as well as amount and type of irrigation solution, and method of irrigation affect the extent of AED [4].
Each canal preparation technique involves the formation of dentinal chips and their extrusion to periapical tissues despite maintaining proper working length [1, 2, 4, 7]. Endodontic treatment methods differ in the scale of this phenomenon [2].
The aim of the study was to review the causes of post-operative pain after root canal treatment, in parti­cular the impact of the technique of root canal instrumentation and file system used.

Incidence of post-operative pain

Pak and White [9] claimed that the frequency of post-operative pain amounts up to 40% in the first 24 hours after procedure, and decreases to 11% two days after treatment, and then remain constant for a week. It is supported by a previous study [10], showing the incidence of post-operative pain of 72% in the first 24 hours and of 39% after 6 days. Other authors [11] reported the incidence of post-operative pain of 25-40% in the first 48 hours, regardless of the pulp and periapical tissue diseases. After a week, the value decreased to 11%.
In contrast to these results, a study by Torabinejad et al. showed that the incidence of post-operative pain in the first 96 hours after procedure was low regardless of instrumentation technique and analgesics intake [12].

Intensity of post-operative pain variations

The highest post-operative pain intensity is observed at an early stage after endodontic treatment [9]. It may originate from inflammation activity, preparation of apical area, anesthetic injection, rubber dam clamp pressure, and staying with an open mouth for a long time [3].
Gambarini et al. used visual analogue scale to divide post-operative ailments into 4 groups (1 = no pain, 2 = mild pain, 3 = moderate pain, and 4 = severe pain) depending on symptoms intensity. Table 1 presents the comparison of occurrence frequency and post-operative pain intensity in the first 12, 24, and 72 hours after RCT [3, 6, 13].
Research comparing post-operative pain after RCT with hand, rotary, and reciprocating files reported that WaveOne (WO) preparation caused lower pain sensations after 6, 12, and 18 hours post-operatively than both hand and rotary files. Also, in ProTaper Universal (PTU) group ailments, pain was less noticeable after 6 and 12 hours post-operatively in comparison to hand files (p < 0.05) [3].
The use of analgesics was significantly higher in the group treated with hand files, especially within the first 18 hours, when compared to rotary and reciprocating files [3]. On the other hand, there was no significant difference in painkillers intake between patients treated with ProTaper Next (PTN) and WO [13]. Patients suffering from post-operative pain were given 400 mg of ibuprofen [3].

Causes of post-operative pain

The occurrence of post-operative pain depends on host-dependent and operator-dependent factors. The former group involves a history of pre-operative pain and occlusal trauma. The latter group entails mechanical, chemical, and bacterial injury during root canal preparation resulting from AED. AED is one of the main reasons of post-operative pain [5, 6]. Moreover, temporarily applied antiseptics and final filling materials may be extruded to periapical tissues, which would result in acute periapical inflammation. In some cases, this phenomenon can result in delayed or inhi­bited healing [2].
Additionally, root canal instrumentation technique and applied file system impact post-operative pain occurrence [14]. Authors indicated factors related to the tooth, which are the number of roots and tissue condition [11]. Moreover, treatment of asymptomatic periodontitis with periapical lesions predispose the appearance of post-operative pain [6]. A proper root canal chemo-mechanical preparation is the key factor in avoiding this complication. Table 2 shows the factors that may influence incidence of post-operative pain after RCT.

Type of files motion

NiTi files may use continuous rotation (CR), reciprocal motion (RP), or combine motion (CM). Their movement can also be clockwise or counterclockwise. Systems using CR rotate in one direction and complete a full rotary cycle [15]. This motion is used by PTU and PTN (Dentsply Maillefer), Mtwo (VDW), Hyflex (Coltene), and ProDesign Logic (Easy Equipamentos Odontológicos). RP is an oscillating motion; an instrument rotates in one direction and then reverses direction before completing a full rotary cycle [3]. File systems, such as WO and WaveOne Gold (Dentsply Maillefer), Reciproc (VDW), and ProDesign R (Easy Equipamentos Odontológicos) use this type of movement.
The applied system may significantly influence the amount of AED and thus, occurrence of post-operative pain [5]. Hand files produce the greatest AED [5, 7], which may result from an extended period of apical area instrumentation as well as from variable, operator-dependent factors [7]. The employment of balanced forces technique or usage of NiTi instruments reduce this adverse phenomenon due to a better control of pressure that a file exerts on the root canal wall [5, 7]. The number of used files poorly affects the inflammation caused by AED, while kinematic parameters, such as type of motion, shape of a file, and angle of rotation exacerbate the inflammation significantly [7, 14].
Surakanti et al. showed that root canal preparation with Hyflex files produced significantly less AED than WO and PT due to continuous rotary motion [5]. It was supported by another study comparing rotary and reciprocating systems, and reporting that lower debris rate was found after root canal preparation to the size 25/ 05 in ProDesign Logic group comparing with ProDesign R group (4.20% and 12.21%, respectively) [16]. Application of PTN and WO systems leads to periapical displacement of debris, but PTN allows for minimizing this phenomenon. However, the difference was not statistically significant [4, 5]. On the other hand, Twisted File Adaptive was found to have a beneficial ability of cutting dentine and removing debris because of predominance of clockwise motion [6]. A few studies reported no statistically significant differences in AED between rotating and reciprocating systems [17-19]. Interestingly, instrumentation technique might be the most important factor affecting the prevalence of post-operative pain [6]. Its’ frequency and analgesics intake were greater in a group of patients treated with reciprocal systems (WO) [6, 13, 20]. However, these findings were not supported by Kherlakian et al., who found no difference in the incidence of post-operative pain and the usage of analgesics between rotary and reciprocal file systems [21]. The counterclockwise motion may indicate higher AED for reciprocating systems [2]. However, studies results should be considered in a clinical aspect since the irrigation and presence of periapical resistance may cause a greater introduction of debris into periapical tissue [3].

Shape of the instrument

The cross-section and taper of an instrument have a significant impact on dentin cutting ability and debris removal. AED after preparation was found statistically lower in WaveOne Gold than WO [1]. Changing the trian­gular cross-section into equilateral one and the taper from 0.08 to 0.07, provides improvement of an increasement of dentinal space and working efficiency. Instrumentation with self-adjusting file (SAF) introduces less debris into periapical tissues than WO. The reason for that is a better adaptation of SAF to the canal wall, lack of positive pressure, continuous irrigation, and additional activation of the solution. Additionally, SAF produces less AED than hand files due to an advantageous file shape [7].
Interestingly, the file cross-section is thought to be the most important factor contributing to a smaller amount of AED in multi-file rotary systems in comparison to single-file reciprocating ones [5, 14]. The bigger the cross-section of an instrument, the smaller its’ debris area and debris removal ability [22]. S-shaped Reciproc files have greater area for removing debris than triangular PT files, because they enhance the effectiveness of dentine cutting [14]. Moreover, both WO and PT have three cutting edges, which affect slightly cutting effectiveness, leaving a little space for debris evacuation. It results in a troublesome removal of dentinal chips in reciprocating motion. On the other hand, the rotary motion may contribute to coronal shift of debris that counteract AED phenomenon [23].

Apical shaping

Two main methods of root canal shaping, namely foraminal enlargement (FE), which is the preparation of 0.0 mm from apex after establishment with apex locator, and non-foraminal enlargement (NFE), which prepares the canal 1.0 mm shorter after indication APEX on apex locator, were described [24].
The level of post-operative pain after FE and NFE preparation with hand files was found to be comparable [25]. However, FE preparation with NiTi rotary and reciprocating instrument systems resulted in greater post-opera­tive pain comparing with NFE [24]. Moreover, the application of FE method caused higher ailment intensity for rotary systems in comparison with reciprocating ones [26].
Apical preparation is a consequence of chosen files’ type and size. It is a key factor of AED limitation and thus adequate RCT effect [4, 5]. File control during apical area instrumentation may be improved by prior canal orifice preparation [5].
Furthermore, setting the working length to 1 mm in relation to physiological foramen significantly allows reduction of AED [4]. Additionally, accurate control of the working length minimizes the amount of AED [5].
The risk of post-operative pain may be reduced by performing apical patency and glide path prior to root canal instrumentation. Glide path preparation with rotary files (e.g., ProGlider [PG]), reciprocal files (e.g., Reciproc), or hand files (e.g., K-file) must meet velocity and security requirements. It helps maintaining natural canal curvature [11]. Apical dentine plug evaluation should be performed as a prevention of apical third over-preparation [27]. Creating apical patency always results in the introduction of NaOCl into the periapical tissues and less debris extrusion [27]. Moreover, the use of 5.25% NaOCl in irrigation protocol directly affects periodontal ligament response [14].

Other factors

Number of visits during RCT appears to be an important factor for prognosis. Sathorn et al. reported that the healing rate of single-visit treatment amounted to 77.2%, while multi-visit treatment to 71.6% [28]. Post-operative pain after single-visit and multi-visit treatment was found comparable [29]. However, higher post-opera­tive pain incidence and analgesics intake was observed after single-visit treatment [30, 31].
Factors, such as roots number, pre-operative pulp, and periapical tissue condition, also affect the intensity of post-operative pain [2, 32]. A higher incidence of post-operative pain in the group of multi-root teeth comparing with single-root group was revealed [2]. Pulp condition significantly affects post-operative pain prevalence in reciprocating files cases. However, such a relationship does not appear in rotary files group. Moreover, age and gender of patient did not impact the occurrence of this complication [3, 13].


AED seems to be the most important etiological factor of post-operative pain. Intensity of this phenomenon depends on the applied instrument system and the type of motion used. Other factors presumably influencing the frequency and intensity of pain occurrence are less significant.
Differences in presented studies may arise from subjectivity of a patient’s pain sensation. Further research on this issue should be conducted.

Conflict of interest

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.


1. Pedrinha VF, Brandão JMDS, Pessoa OF, Rodrigues PA. Influence of file motion on shaping, apical debris extrusion and dentinal defects: a critical review. Open Dent J 2018; 12: 189-201.
2. Pasqualini D, Corbella S, Alovisi M, et al. Postoperative quality of life following single-visit root canal treatment performed by rotary or reciprocating instrumentation: a randomized clinical trial. Int Endod J 2016; 49: 1030-1039.
3. Shokraneh A, Ajamij M, Farhadi N, Hosseini M, Rohani B. Postoperative endodontic pain of three different instrumentation techniques in asymptomatic necrotic mandibular molars with periapical lesion: a prospective, randomized, double-blind clinical trial. Clin Oral Invest 2017; 21: 413-418.
4. Zhang C, Liu J, Liu L. The influence of ProTaper and WaveOne on apically extruded debris: a systematic review and meta-analysis. J Conserv Dent 2018; 21: 474-480.
5. Surakanti JR, Venkata RP, Vemisetty HK, Dandolu RK, Jaya NM, Thota S. Comparative evaluation of apically extruded debris during root canal preparation using ProTaper™, Hyflex™ and Waveone™ rotary systems. J Conserv Dent 2014; 17: 129-132.
6. Gambarini G, Testarelli L, De Luca M, et al. The influence of three different instrumentation techniques on the incidence of post­operative pain after endodontic treatment. Ann Stomatol (Roma) 2013; IV: 152-155.
7. Western JS, Dicksit DD. Apical extrusion of debris in four different endodontic instrumentation systems: A metaanalysis. J Conserv Dent 2017; 20: 30-36.
8. Siddique R, Nivedhitha MS. Effectiveness of rotary and reciprocating systems on microbial reduction: a systematic review. J Conserv Dent 2019; 22: 114-122.
9. Pak JG, White SN. Pain prevalence and severity before, during, and after root canal treatment: a systematic review. J Endod 2011; 37: 429-438.
10. DiRenzo A, Gresla T, Johnson BR, Rogers M, Tucker D, BeGole EA. Postoperative pain after 1- and 2-visit root canal therapy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002; 93: 605-610.
11. Keskin C, Sivas Yilmaz Ö, Inan U, Özdemir Ö. Postoperative pain after glide path preparation using manual, reciprocating and continuous rotary instruments: a randomized clinical trial. Int Endod J 2019; 52: 579-587.
12. Torabinejad M, Cymerman JJ, Frankson M, Lemon RR, Maggio JD, Schilder H. Effectiveness of various medications on postoperative pain following complete instrumentation. J Endod 1994; 20: 345-354.
13. Kurnaz S. Comparison of Postoperative Pain after Foraminal Enlargement of Necrotic Teeth Using Continuous Rotary System and Reciprocating Instrument: A Randomized Clinical Trial. Niger J Clin Pract 2020; 23: 212-218.
14. Caviedes-Bucheli J, Castellanos F, Vasquez N, Ulate N, Munoz HR. The influence of two reciprocating single-file and two rotary-file systems on the apical extrusion of debris and its biological relationship with symptomatic apical periodontitis. a systematic review and meta-analysis. Int Endod J 2016; 49: 255-270.
15. Gambarini G, Piasecki L, Miccoli G, et al. Classification and cyclic fatigue evaluation of new kinematics for endodontic instruments. Aust Endod J 2019; 45: 154-162.
16. Pinto JC, Pivoto-João MMB, Espir CG, Ramos MLG, Guerreiro-Tanomaru JM, Tanomaru-Filho M. Micro-CT evaluation of apical enlargement of molar root canals using rotary or reciprocating heat-treated NiTi instruments. J Appl Oral Sci 2019; 12: 27.
17. Küçükyilmaz E, Savas S, Saygili G, Uysal B. Assessment of apically extruded debris and irrigant produced by different nickel-titanium instrument systems. Braz Oral Res 2015; 29: 1-6.
18. Kirchhoff AL, Fariniuk LF, Mello I. Apical extrusion of debris in flat-oval root canals after using different instrumentation systems. J Endod 2015; 41: 237-241.
19. Kuştarcı A, Er K. Efficacy of laser activated irrigation on apically extruded debris with different preparation systems. Photomed Laser Surg 2015; 33: 384-389.
20. Nekoofar MH, Sheykhrezae MS, Meraji N, et al. Comparison of the effect of root canal preparation by using WaveOne and ProTaper on postoperative pain: a randomized clinical trial. J Endod 2015; 41: 575-578.
21. Kherlakian D, Cunha RS, Ehrhardt IC, Zuolo ML, Kishen A, da Silveira Bueno C. Comparison of the incidence of postoperative pain after using 2 reciprocating systems and a continuous rotary system: a prospective randomized clinical trial. J Endod 2016; 42: 171-176.
22. Monguilhott Crozeta B, Damião de Sousa-Neto M, Bianchi Leoni G, Francisco Mazzi-Chaves J, Terezinha Corrêa Silva-Sousa Y, Baratto-Filho F. A micro-computed tomography assessment of the efficacy of rotary and reciprocating techniques for filling material removal in root canal retreatment. Clin Oral Investig 2016; 20: 2235-2240.
23. Bürklein S, Hinschitza K, Dammaschke T, Schäfer E. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Int Endod J 2012; 45: 449-461.
24. Yaylali IE, Teke A, Tunca YM. The effect of foraminal enlargement of necrotic teeth with a continuous rotary system on postoperative pain: A randomized controlled trial. J Endod 2017; 43: 359-363.
25. Silva EJ, Menaged K, Ajuz N, Monteiro MR, de Coutinho-Filho TS. Postoperative pain after foraminal enlargement in anterior teeth with necrosis and apical periodontitis: a prospective and rando­mized clinical trial. J Endod 2013; 39: 173-176.
26. Junior JAC, Coelho MS, Kato AS, et al. The effect of foraminal enlargement of necrotic teeth with the Reciproc System on postope­rative pain: A prospective and randomized clinical trial. J Endod 2016; 42: 8-11.
27. Myers GL, Montgomery S. A comparison of weights of debris extruded apically by conventional filing and Canal Master techniques. J Endod 1991; 17: 275-279.
28. Sathorn C, Parashos P, Messer H. Effectiveness of single-versus multiple-visit endodontic treatment of teeth with apical periodontitis: a systematic review and meta-analysis. Int Endod J 2005; 38: 347-355.
29. Wang C, Xu P, Ren L, Dong G, Ye L. Comparison of post-obturation pain experience following one-visit and two-visit RCT on teeth with vital pulps: a randomized controlled trial. Int Endod J 2010; 43: 692-697.
30. Figini L, Lodi G, Gorni F, Gagliani M. Single versus multiple visits for endodontic treatment of permanent teeth: a Cochrane systema­tic review. J Endod 2008; 34: 1041-1047.
31. Su Y, Wang C, Ye L. Healing rate and post-obturation pain of single-versus multiple-visit endodontic treatment for infected root canals: a systematic review. J Endod 2011; 37: 125-132.
32. Arias A, de la Macorra JC, Hidalgo JJ, Azabal M. Predictive models of pain following root canal treatment: a prospective clinical study. Endod J 2013; 46: 784-793.
This is an Open Access journal, all articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0). License (http://creativecommons.org/licenses/by-nc-sa/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.
Quick links
© 2022 Termedia Sp. z o.o. All rights reserved.
Developed by Bentus.