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 Table of Contents  
Year : 2017  |  Volume : 29  |  Issue : 2  |  Page : 115-119

Clinical evaluation of maintenance of apical patency in postendodontic pain: An in vivo study

Department of Conservative Dentistry and Endodontics, Bhojia Dental College, Baddi, Himachal Pradesh, India

Date of Web Publication6-Nov-2017

Correspondence Address:
Nisha Garg
W/O Dr. Amit Garg, House No. 2347, Sector 23-C, Chandigarh - 160 023
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_28_17

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Aim: The purpose of this study was to compare the incidence of postoperative pain in 80 endodontically treated teeth, with and without apical patency, in relation to some diagnostic factors (vitality, presence of preoperative pain, group of treated teeth).
Materials and Methodology: Apical patency was maintained during shaping procedures with a #10 K-file in one group (n = 40) and not in the other (n = 40). Root canal treatment was done in single visit. Pain was recorded 1st day, 2nd day and 7th day using VAS scale.
Results: There were no statistically significant differences between patency and non patency groups regarding incidence and degree of postoperative pain. Only preoperative pain has significant effect on postoperative pain.
Conclusion: Our study concluded that maintenance of apical patency did not increase the incidence of postoperative pain when considering all variables together.

Keywords: Apical patency, postendodontic pain, recapitulation, working length

How to cite this article:
Garg N, Sharma S, Chhabra A, Dogra A, Bhatia R, Thakur S. Clinical evaluation of maintenance of apical patency in postendodontic pain: An in vivo study. Endodontology 2017;29:115-9

How to cite this URL:
Garg N, Sharma S, Chhabra A, Dogra A, Bhatia R, Thakur S. Clinical evaluation of maintenance of apical patency in postendodontic pain: An in vivo study. Endodontology [serial online] 2017 [cited 2021 Dec 5];29:115-9. Available from: https://www.endodontologyonweb.org/text.asp?2017/29/2/115/217711

  Introduction Top

Pulpal remnants and dentinal chips get clogged in the apical region during instrumentation which is responsible for blockage of root canal, mainly in its apical third. This blockage can be prevented if we maintain patency of the canal before and during instrumentation.[1] Apical patency is a technique in which apical portion of the canal is maintained free of debris by passing a small number file through the apical foramen.[2]

Buchanan first discussed the concept of apical patency and said that if patency file is used during instrumentation, the blockage of apical portion can be avoided. He defined patency file as a small flexible K-file, which is passively moved through the apical constriction without widening it. Initially, patency files were used to negotiate the canals.[3] A patency file is passed through the canal 1 mm beyond the already set working length (WL).[4] If canal patency is maintained throughout instrumentation, many iatrogenic errors can be prevented, for example, apical transportation, perforation, ledge formation, etc.[3]

Bacterial biofilm is present around the apical foramen of infected nonvital teeth.[5] If patency is maintained in these teeth, it can help in removal of this periapical bacterial biofilm. In vital cases, dentinal debris gets clogged in apical region which leads to the formation of an apical plug that interferes with WL determination. In such cases, apical patency prevents clogging of dentinal debris or chips in the apical portion of the canal.[6]

There are many advantages of maintaining apical patency, i.e., it prevents many accidents (ledges, apical transportation, and apical perforation), maintains the anatomy of apical portion of the canal, minimizes the risk of loss of length, and eases irrigation in the apical third of the canal.[3],[7] Furthermore, there are various reasons why apical patency is not recommended. One such reason is that it leads to the debris extrusion periapically, which further leads to postoperative pain or discomfort. Some authors do not recommend the patency concept.[8] They think that if patency files (even the smallest one) are passed repeatedly 1 mm beyond the apical foramen, it leads to inflammation of periapical area which further leads to severe postoperative pain.[4],[8]

If apical patency is satisfactorily maintained throughout the instrumentation, it would not lead to postoperative problems.[4] The benefits of maintaining apical patency exceed the possible injury; it might cause because its main purpose is to prevent clogging of dentinal debris mainly in apical region of the canal which hinders the determination of WL.[6]

The purpose of this study was to assess whether maintenance of apical patency during instrumentation leads to postoperative pain in single visit, considering different diagnostic factors such as position (anterior or posterior), pulpal status of the tooth (vital or nonvital) to be treated, and presence or absence of preoperative pain.

  Materials and Methods Top

The study was conducted on 80 teeth (40 single and 40 multirooted teeth) indicated for root canal treatment in single visit. The study was approved by Ethical Committee of the institution. All patients were instructed about the aims and design of the study, and written authorizations were collected from patients before their inclusion.

Failure to obtain patient's consent, presence of accidents or complications during treatment (impossibility to achieve apical patency in any canal, calcified canals), grossly decayed teeth where rubber dam isolation was difficult, need for retreatment, and pregnancy came under exclusion criteria.

The preoperative data were collected from all the patients, for example, preoperative pain, pulpal status, and group of the teeth (anterior or posterior teeth). The pulpal status was checked with electric pulp tester (Digitest Parkell Inc., USA). The presence or absence of preoperative pain was also recorded and noted for two groups (anterior/posterior).

Preoperative radiographic examination was performed before initiating the actual procedure. After confirming eligibility, the patients were randomly divided into two groups: patency (P) and nonpatency (NP) group (A and B, respectively). These groups were further subdivided into:

  • Group A: Nonapical patency group (n = 40)

    • Subgroup AI: Apical patency was not maintained in vital teeth (n = 20)

      • Subgroup AIa: Apical patency was not maintained in vital anterior teeth (n = 10)
      • Subgroup AIb: Apical patency was not maintained in vital posterior teeth (n = 10)

    • Subgroup AII: Apical patency was not maintained in nonvital teeth (n = 20)

      • Subgroup AIIa: Apical patency was not maintained in nonvital anterior teeth (n = 10)
      • Subgroup IIAb: Apical patency was not maintained in nonvital posterior teeth (n = 10)

  • Group B: Apical patency group (n = 40)

    • Subgroup BI: Apical patency was maintained in vital teeth (n = 20)

      • Subgroup BIa: Apical patency was maintained in vital anterior teeth (n = 10)
      • Subgroup BIb: Apical patency was maintained in vital posterior teeth (n = 10)

    • Subgroup BII: Apical patency was maintained in nonvital teeth (n = 20)

      • Subgroup BIIa: Apical patency was maintained in nonvital anterior teeth (n = 10)
      • Subgroup BIIb: Apical patency was maintained in nonvital posterior teeth (n = 10).

Local anesthesia (2% lidocaine hydrochloride and epinephrine 1:200,000; Cadila Pharmaceuticals Ltd., India) was given to all patients using conventional nerve blocks. The following steps were done during standard treatment procedure; tooth was isolated using rubber dam. The access cavity preparation was done using round bur (Mani Inc., Japan) and Endo Z bur (Dentsply Maillefer, Switzerland) with high-speed handpiece. Number 10 K-file was used to negotiate the canals with the help of canal prep (Ammdent, India). WL was confirmed using apex ID apex locator (Sybron Endo, Orange, CA, USA) and then confirmed radiographically. If there is disagreement between radiographic and electronic WL measurements, the apex locator was selected. Coronal flaring was done with Endoflare (Micro-Mega, Besancon, France). Cleaning and shaping was done with Hero Shaper file (Micro-Mega, Besancon, France) using crown-down technique. In Group A (patency group), between each instrument change, a size 10 K-file was passed 1 mm beyond the WL. In group B (NP group), all efforts were taken to prevent the surpassing of patency file beyond the WL at all times during treatment. WL was reconfirmed using an apex locator after instrumentation of the coronal and middle thirds of the canal. Irrigation was performed with saline, 5 ml of 3% NaOCl solution (Dentpro, India), and chlorhexidine (Dentochlore, Ammdent, India) after each instrumentation. The master cone radiograph was taken to confirm the correct length. Canals were dried using paper points. AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland) was applied on the walls of the canal. After that, the master cone was introduced into the canal up to the WL, and accessory gutta-percha cones (META Biomed Co. Ltd, Korea) were laterally compacted using spreaders. Excess gutta-percha was cutoff at canal orifice using heated excavator, and access cavity was restored using direct composite resin. Incidence of postoperative pain was checked on day 1 and 2. Final evaluation was done on the 7th day. After completion of the treatment, visual analog scale forms were filled by the patients. In this form, a 10 cm line is used to provide a range of scores from 0 to 10 where numbers 0–10 indicate severity of pain as: No pain (0), mild pain (1–2), moderate pain (3–6), and severe pain (7–10 mm).

  Results Top

Results of this study are shown in [Table 1] and [Table 2].
Table 1: Mean standard deviation and median of pain score of all the eight groups on all the days

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Table 2: Comparison of pain scores of the two groups

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No significant difference was found betweenPand NP groups regarding degree of pain on the 1st, 2nd, and 7th days. No significant difference was found when pain scores of all the two groups were compared using Mann–Whitney U-test on the 1st, 2nd, and 7th days. [Table 1] depicts mean of pain scores of all groups. [Table 2] depicts mean of pain scores of two groups (P = 0.836, 0.534, and 0.559 on the 1st, 2nd, and 7th days, respectively).

When anterior teeth were compared with posterior teeth, no statistically significant differences were found betweenPand NP groups regarding degree and incidence of postoperative pain (P > 0.05).

Statistically insignificant relation of postoperative pain was found on 1st, 2nd and 7th day. According to Mann-Whitney U-test Test, P = 0.836, 0.534 and 0.559 on the 1st, 2nd, and 7th days, respectively.

Mean of pain of all the groups on 1st, 2nd, and 7th days is depicted in [Graph 1],[Graph 2],[Graph 3], respectively.

  Discussion Top

Main aim of this study was to assess whether maintaining apical patency leads to postoperative pain or not. Endodontic pain is defined as pain of any degree that occurs after the initiation of root canal treatment.[9] Clem defined postoperative pain as a pain existing in a patient who had previously experienced none and/or increase in an already existing pain. Pain is a subjective sign, so it is difficult to assess accurately.[10] It is very difficult to quantify or qualify pain in any statistical analysis.

In this study, diagnostic factors such as vitality of teeth, group of teeth (anterior or posterior teeth) as well as preoperative clinical findings such as preoperative pain were assessed from all patients. There was no significant difference of pain between two groups (patency and nonpatency groups). Our findings are in accordance with other studies conducted by Arias et al.[1] and Sharaan andAboul-Enein.[11] In our study, the only finding that significantly influences the incidence of postoperative pain was the presence of preoperative pain. This finding was in agreement with other studies conducted by Siqueira et al.,[12] Torabinejad et al.,[13] and Walton and Fouad.[14] Whereas the results of other studies show no correlation between incidence of postoperative pain and presence of preoperative pain.[15],[16] In this study, data revealed that there is decrease in mean pain intensity over time after endodontic treatment in both the groups. The findings of this study were in accordance with other studies which showed that after endodontic treatment, there was a significant decline in pain.[12],[13],[14] Negm showed that the postoperative pain after endodontic treatment may be reduced due to function of pain resolution with healing.[9]

The results of the present study were in agreement with the findings of others studies that showed the benefits of apical patency during instrumentation.[4],[17],[18] Flanders stated that failure of endodontic treatment occurs if apical patency was not maintained throughout the instrumentation as a portion of the root canal is left uninstrumented.[7] The patency concept uses the smaller number files which maintains a limited apical opening that reduces the periapical extrusion of debris. Researchers reported that patency file usage could reduce the formation of smear layer.[19] Moreover, it was reported that outcome of endodontic treatment is closely associated with the accessibility of instruments to the apical constriction. High success rate was seen in cases where instruments had accessibility to apical constriction of canal than those with inaccessible apical constriction.[20] In a study by Sanchez et al., it was reported that if patency was maintained during instrumentation, there were less chances of canal transportation.[21]

On the contrary, others stated that maintaining apical patency during instrumentation could lead to periapical extrusion of dentin debris and irrigants, and periapical tissue damage may occur due to over enlargement of the apical foramen.[22],[23] Holland et al. assessed the periapical healing after maintaining apical patency during instrumentation and found that best results of periapical healing were seen when apical patency was not maintained.[23] It was reported that periapical tissue injury could occur if large instruments were used to maintain apical patency. Using large instruments to maintain apical patency also led to disruption of apical stop and periapical extrusion of a large amount of infected debris, which led to postoperative discomfort and hampered the outcome of endodontic therapy.[24],[25] Gutiérrez et al. showed that #15 K-file when passed through apical foramen fractured, the cementum and dentinal chips were seen under scanning electron microscope.[24] In this study, small files (#10 K-file) were used gently to guarantee that the canal was negotiated without any further apical enlargement. Hence, we can say that maintaining apical patency during instrumentation did not significantly affect the incidence or intensity of postoperative pain.

  Conclusion Top

Apical patency is not associated with increased risk of postoperative pain according to this study, but it might influence the success rate of endodontic treatment. As the follow-up of this study was for a short duration, it was not possible to find the success rate of endodontic treatment after maintaining apical patency.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Arias A, Azabal M, Hidalgo JJ, de la Macorra JC. Relationship between postendodontic pain, tooth diagnostic factors, and apical patency. J Endod 2009;35:189-92.  Back to cited text no. 1
American Association of Endodontist. Glossary of Endodontics Terms. 7th ed. Chicago, IL: American Association of Endodontist; 2003.  Back to cited text no. 2
Buchanan LS. Management of the curved root canal. J Calif Dent Assoc 1989;17:18-25, 27.  Back to cited text no. 3
Cailleteau JG, Mullaney TP. Prevalence of teaching apical patency and various instrumentation and obturation techniques in United States dental schools. J Endod 1997;23:394-6.  Back to cited text no. 4
Lomçali G, Sen BH, Cankaya H. Scanning electron microscopic observations of apical root surfaces of teeth with apical periodontitis. Endod Dent Traumatol 1996;12:70-6.  Back to cited text no. 5
Souza RA. The importance of apical patency and cleaning of the apical foramen on root canal preparation. Braz Dent J 2006;17:6-9.  Back to cited text no. 6
Flanders DH. Endodontic patency. How to get it. How to keep it. Why it is so important. N Y State Dent J 2002;68:30-2.  Back to cited text no. 7
Buchanan LS. Cleaning and shaping of the root canal system. In: Cohen S, Burns RC, editors. Pathways of the Pulp. 5th ed. St. Louis, MO: Mosby; 1991.  Back to cited text no. 8
Negm MM. Intracanal use of a corticosteroid-antibiotic compound for the management of posttreatment endodontic pain. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:435-9.  Back to cited text no. 9
Clem WH. Posttreatment endodontic pain. J Am Dent Assoc 1970;81:1166-70.  Back to cited text no. 10
Sharaan M, Aboul-Enein NM. Relationship between post-preparation pain and apical patency: A randomized clinical trial. Gulf Med J 2012;1:96-101.  Back to cited text no. 11
Siqueira JF Jr., Rôças IN, Favieri A, Machado AG, Gahyva SM, Oliveira JC, et al. Incidence of postoperative pain after intracanal procedures based on an antimicrobial strategy. J Endod 2002;28:457-60.  Back to cited text no. 12
Torabinejad M, Kettering JD, McGraw JC, Cummings RR, Dwyer TG, Tobias TS. Factors associated with endodontic interappointment emergencies of teeth with necrotic pulps. J Endod 1988;14:261-6.  Back to cited text no. 13
Walton R, Fouad A. Endodontic interappointment flare-ups: A prospective study of incidence and related factors. J Endod 1992;18:172-7.  Back to cited text no. 14
Albashaireh ZS, Alnegrish AS. Postobturation pain after single- and multiple-visit endodontic therapy. A prospective study. J Dent 1998;26:227-32.  Back to cited text no. 15
Glennon JP, Ng YL, Setchell DJ, Gulabivala K. Prevalence of and factors affecting postpreparation pain in patients undergoing two-visit root canal treatment. Int Endod J 2004;37:29-37.  Back to cited text no. 16
Sathorn C, Parashos P, Messer H. The prevalence of postoperative pain and flare-up in single- and multiple-visit endodontic treatment: A systematic review. Int Endod J 2008;41:91-9.  Back to cited text no. 17
Negishi J, Kawanami M, Ogami E. Risk analysis of failure of root canal treatment for teeth with inaccessible apical constriction. J Dent 2005;33:399-404.  Back to cited text no. 18
Goldberg F, Massone EJ. Patency file and apical transportation: Anin vitro study. J Endod 2002;28:510-1.  Back to cited text no. 19
Lambrianidis T, Tosounidou E, Tzoanopoulou M. The effect of maintaining apical patency on periapical extrusion. J Endod 2001;27:696-8.  Back to cited text no. 20
Sanchez JA, Duran-Sindreu F, Matos MA, Carabaño TG, Bellido MM, Castro SM, et al. Apical transportation created using three different patency instruments. Int Endod J 2010;43:560-4.  Back to cited text no. 21
Ricucci D, Langeland K. Apical limit of root canal instrumentation and obturation, part 2. A histological study. Int Endod J 1998;31:394-409.  Back to cited text no. 22
Holland R, Sant'Anna Júnior A, Souza VD, Dezan Junior E, Otoboni Filho JA, Bernabé PF, et al. Influence of apical patency and filling material on healing process of dogs' teeth with vital pulp after root canal therapy. Braz Dent J 2005;16:9-16.  Back to cited text no. 23
Gutiérrez JH, Brizuela C, Villota E. Human teeth with periapical pathosis after overinstrumentation and overfilling of the root canals: A scanning electron microscopic study. Int Endod J 1999;32:40-8.  Back to cited text no. 24
Tinaz AC, Alacam T, Uzun O, Maden M, Kayaoglu G. The effect of disruption of apical constriction on periapical extrusion. J Endod 2005;31:533-5.  Back to cited text no. 25


  [Table 1], [Table 2]

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