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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 28  |  Issue : 2  |  Page : 127-131

Effect of maintaining apical patency and passive ultrasonic irrigation on irrigant penetration into the apical third of root canals: An in vivo study


1 Department of Conservative Dentistry and Endodontics, C.S.M.S.S. Dental College and Hospital, Aurangabad, Maharashtra, India
2 Department of Conservative Dentistry and Endodontics, Nair Dental College and Hospital, Mumbai, Maharashtra, India

Date of Web Publication9-Dec-2016

Correspondence Address:
Jalpa Mansukh Tank
A-2/3 Sara Pride, Kalda Corner, Aurangabad - 431 005, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-7212.195422

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  Abstract 


Introduction: The aim of this study was to determine whether the use of a patency file and passive ultrasonic irrigation (PUI) is related to the presence of a radiopaque irrigating solution in the apical third of human root canals in vivo.
Materials and Methods: 20 human root canals were randomly divided into 4 groups. 1: Conventional needle irrigation without apical patency, 2: PUI without apical patency, 3: Conventional needle irrigation with apical patency, 4: PUI with apical patency. Apical patency was maintained with a no. 10 K-file 1mm beyond the working length. PUI was done using an endosonic file attached to the ultrasonic unit. The canals were shaped with the Pro Taper system. Irrigation was performed with solution prepared with a radiopaque contrast medium and sodium hypochlorite 5.25%. Digital images were taken and a calibrated reader determined the presence or absence of the irrigating solution in the apical third.
Results: Significantly more canals with irrigant in the apical third were found after PUI and after maintain apical patency.
Conclusion: PUI and maintaining apical patency improves irrigant penetration.

Keywords: Apical patency; irrigant penetration; passive ultrasonic irrigation.


How to cite this article:
Kamra AI, Tank JM, Banga KS. Effect of maintaining apical patency and passive ultrasonic irrigation on irrigant penetration into the apical third of root canals: An in vivo study. Endodontology 2016;28:127-31

How to cite this URL:
Kamra AI, Tank JM, Banga KS. Effect of maintaining apical patency and passive ultrasonic irrigation on irrigant penetration into the apical third of root canals: An in vivo study. Endodontology [serial online] 2016 [cited 2019 Aug 25];28:127-31. Available from: http://www.endodontologyonweb.org/text.asp?2016/28/2/127/195422




  Introduction Top


Microorganisms and their end products are considered the primary etiological factors for pulp and periapical diseases,[1] and hence, their elimination is crucial for successful endodontic therapy.[2] Cleaning and shaping procedures do not completely eliminate all bacteria present in the root canal, mainly because of the anatomic complexity of the root canal system, especially in the apical third.[3] These areas include ramifications, deltas, fins, and other irregularities, which are often missed by instrumentation.[4] Thus, the microorganisms can survive by colonizing organic tissue and dentin or getting nutrients from the periradicular tissues and releasing byproducts associated with the development of apical periodontitis.[3]

Irrigation is the essential part of root canal treatment as it allows for cleaning beyond root canal instruments. Endodontic irrigating solutions should dissolve pulp tissue and remove dentin debris, smear layer, and bacteria.[5] Sodium hypochlorite (NaOCl) is currently the most commonly used irrigating solution because of its tissue-dissolving and antimicrobial properties.[6] Factors affecting the ability of an irrigant to penetrate the apical root canal include the internal anatomy of a canal, the presence of dentin or pulp tissue, the mode of delivery of the solution, and agitation of an irrigant through active irrigation techniques.[7]

In addition, blockage of the root canal occurring due to the accumulation of soft tissue remnants or dentinal debris in the apical region also prevents the penetration of the irrigant apically.[8]

Currently, different irrigation techniques and devices are being used to improve the disinfection of root canal system. Agitation by passive ultrasonic irrigation (PUI) may help the irrigating solution reach the apical third by activating the NaOCl, thus improving the cleaning efficiency of the irrigating solution.[9],[10],[11] Although it has been shown that PUI is significantly more effective at reducing bacterial amount from the root canals when compared with conventional endodontic needle irrigation, there is insufficient evidence on its effectiveness in irrigant penetration in the apical third in vivo.[12]

It has also been shown that maintaining apical patency (AP) prevents the accumulation of debris in the apical portion of the root canal.[13],[14] However, very fewin vivo studies have investigated the effectiveness of maintaining AP on irrigant penetration.

Hence, the purpose of thisin vivo study was to determine whether maintaining AP and PUI improves the delivery of a solution of contrast medium and NaOCl (5.25%) into the apical third of human root canals.


  Materials and Methods Top


This study was conducted following the requirements of the Ethical Committee of the Institute. Written informed consent was obtained from each of the patients participating in the study. Exclusion criteria were curved canals, allergy to any of the components of the formula, pregnancy, or failure to sign informed consent.

A total of 64 human root canals consisting of the straight distal roots of mandibular molars with one canal with either irreversible pulpitis or necrotic pulp and no signs of root resorption were used in the study. Sixty of these root canals were randomly assigned into two separate groups (n = 30) using simple randomization method:

  • Group 1 – No AP (NAP)
  • Group 2 –AP.


These groups were further divided into two subgroups (SG) each (n = 15), depending on whether conventional needle irrigation (CNI) or PUI was used [Figure 1]. Two teeth were used as negative controls and the remaining two teeth were used as positive controls.
Figure 1: Flow chart illustrating subdivisions of the groups

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A sterile, intravascular contrast medium containing iodine (iopamidol) was mixed with 5.25% of NaOCl by a chemist to have an irrigating solution with a density and surface tension similar to that of NaOCl 2–5%.

Subgroup 1

After coronal flaring of the cervical third of the root canals with Gates Glidden drills size 2 and 3, a no. 10 K-file was used to determine the working length (WL) with the use of the apex locator (Apex ID, Sybron Dental Specialties) at the 0.0 reading of the device and was confirmed radiographically. Hand files of nos. 10, 15, and 20 K were used until the WL was reached, along with passive irrigation with 1 ml of the irrigating solution was used to the deepest penetration of a 27-gauge, side-vented needle (ultradent) or to within 2 mm of the WL when possible. The irrigant was delivered for 20 s. Then, the root canals were enlarged using the Protaper System (Dentsply) till F3 following manufacturer's suggested sequence to the WL. Frequent recapitulation and irrigation with 1 ml of the solution for 20 s were done between each instrumentation. After enlarging the root canal till F3, irrigation was done and digital image was taken with Suni digitals [Figure 2].
Figure 2: Subgroup 1: Radiopaque irrigant not present in the apical 2 mm of the root canal

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Subgroup 2

The same procedure was performed as in SG 1, but after the shaping procedure, PUI was done using a U-file (Mani) attached to a file adapter at 3 mm from the WL connected to the ultrasonic unit (Top selector, APOZA) at power 5 for 20 s. A digital image was taken.

Subgroup 3

The same procedure was performed as in SG 1, but the 10 K-file was inserted 1 mm past the WL to maintain patency between each instrument and before each irrigation sequence [Figure 3].
Figure 3: Subgroup 3: Radiopaque irrigant present in the apical 2 mm of the root canal

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Subgroup 4

The same procedure was performed as in SG 2, but the 10 K-file was inserted 1 mm past the WL to maintain patency between each instrument and before each irrigation sequence [Figure 4].
Figure 4: Subgroup 4: Radiopaque irrigant present in the apical 2 mm of the root canal

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For calibration of the readers, two teethin vivo were used as positive controls in which the radiopaque solution was placed into the canal to determine whether it could be detected by the blinded readers. Two teeth were used as negative controls, wherein no intracanal radiopaque solution was used. Digital images were taken after the cleaning and shaping procedure.

Two blinded, calibrated readers observed the digital images to determine the presence or absence of the irrigating solution in the apical 2 mm of the root canals and recording no (absence of irrigating solution) or yes (presence of irrigating solution).

Paralleling technique of intraoral periapical radiograph was implemented throughout the study to maintain the standardization of pre- and post-cleaning and shaping images.

Statistical analysis

Consensus data of the presence or absence of the irrigating solution (yes or no) were compared separately between the two groups and 4 SGs. Results were analyzed with the Chi-square test.


  Results Top


Radiopaque irrigant was present in the canals of both positive controls and absent in the negative controls. Of all the thirty samples in NAP group, 12 samples showed irrigant in apical 2 mm on the digital images compared to 19 in AP group.

The number of canals showing the presence of the irrigant in the apical 2 mm as visible on the digital images is shown in [Table 1]. Significantly more canals with irrigant in the apical third were found after PUI than with CNI. We found significantly more canals with irrigant in the apical third after maintaining AP than without maintaining AP. However, when used in combination, PUI along with maintaining AP did not show a significant difference in irrigant penetration in apical third when compared to PUI done without maintaining AP [Table 2].
Table 1: Presence of irrigant in apical 2 mm, n (%)

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Table 2: Comparison between subgroups regarding the presence of irrigant in the apical 2 mm as seen on the digital images

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  Discussion Top


The purpose of thisin vivo study was to determine the effect of maintaining AP and PUI in improving the delivery of irrigant in the apical third of human root canals. Distal canal of mandibular molars was used in the study as it is normally straight all the way to the apex and quite large, which makes instrumentation easy.[15]

One of the main problems when analyzing irrigant penetration inside the canal with a radiographic technique is the need to add radiopaque material to the irrigant solution without altering any of the properties of the NaOCl. Therefore, the chemist was instructed to mix the radiopaque material with NaOCl solution in a proportion that the density and surface tension of the final irrigating solution are similar to that of NaOCl 2–5%.

The root canals in the study were enlarged till the F3 Protaper file because the diameter of the last instrument used at the WL plays a very important role in the penetration of irrigants into the root canal. Salzgeber and Brilliant,[16] Chow,[17] and Senia et al.[18] showed that very little, if any solution reaches the apical third before the root canal system, is flared to accommodate a size 30 file.

In SG 1, two samples showed irrigant in apical 2 mm on the digital images compared to seven in SG 3. This study is in agreement with the previousin vivo studies that have shown that maintaining AP facilitates the penetration of irrigants into apical areas of the root canal system.[7],[19] It has been demonstrated that the chemical reaction between NaOCl and organic tissue present in the root canal leads to the formation of small bubbles of ammonia and carbon dioxide, and because the root canal behaves as a closed tube system, these bubbles get trapped in the closed end of the tube. This situation has been previously described as the vapor lock effect.[20] The results may be due to the ability of the patency file to remove the vapor lock effect and also prevents the accumulation of debris in the apical region. During PUI, the U-file was placed 3 mm short of WL to prevent apical extrusion of the irrigant.

The conventional irrigation needle was placed 2 mm short of WL in all canals used in this research because there are studies that have shown that this needle allows the release of the irrigant solution from 1 to 1.5 mm deeper into the canal.[20],[21] However, the results of thisin vivo study show that CNI is not very effective in applying irrigant solution in the apical root canal beyond the needle tip. This is in agreement with a previous study by Munoz et al.[22]

In SG 1, two samples showed irrigant in apical 2 mm on the digital images compared to ten in SG 2. In SG 3, seven samples showed irrigant in apical 2 mm on the digital images compared to 12 in SG 4. The results indicate that PUI obtained significantly better solution penetration almost to the WL, when compared with endodontic needle. Many studies have demonstrated that ultrasonic irrigant activation is more efficient than conventional needle in removing the remnants of pulp tissue and dentin debris from root canals.[23],[24] During ultrasonic irrigant activation, the file oscillation allows the irrigant to flow into the irregularities of the canal, accessing areas that were not touched by the instruments and providing better cleanliness of the root canal system.[25] Results of the present study are in accordance with these statements.

In SG 2, ten samples showed irrigant in apical 2 mm on the digital images compared to 12 in SG 4. The results were insignificant indicating that when used in combination maintaining AP with PUI does not give better irrigant penetration in apical third than the penetration obtained when PUI is used alone. This can be due to the better effectiveness of PUI in removing vapor lock than maintaining AP.

One of the alleged reasons for not striving for AP is the possible extrusion of debris through the apical foramen.[26] Although no complications such as.increased postoperative pain or transportation of the major foramen were seen in a study conducted by Arias et al.[27]


  Conclusion Top


From our data, it can be concluded that maintaining AP improves the delivery of irrigants into the apical third of human root canals. In addition, PUI is more effective than conventional endodontic needles in delivering irrigant to WL of the root canals. However, when used in combination, PUI along with maintaining AP does not improve irrigant penetration as compared to when PUI is used alone.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Grossman LI, Meinmamn BW. Solution of pulp tissue by chemical agents. J Am Dent Assoc 1941;8:223-5.  Back to cited text no. 1
    
2.
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3.
Nair PN, Henry S, Cano V, Vera J. Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after “one-visit” endodontic treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:231-52.  Back to cited text no. 3
    
4.
Peters OA. Current challenges and concepts in the preparation of root canal systems: A review. J Endod 2004;30:559-67.  Back to cited text no. 4
    
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Vera J, Arias A, Romero M. Effect of maintaining apical patency on irrigant penetration into the apical third of root canals when using passive ultrasonic irrigation: Anin vivo study. J Endod 2011;37:1276-8.  Back to cited text no. 7
    
8.
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9.
Jiang LM, Verhaagen B, Versluis M, Langedijk J, Wesselink P, van der Sluis LW. The influence of the ultrasonic intensity on the cleaning efficacy of passive ultrasonic irrigation. J Endod 2011;37:688-92.  Back to cited text no. 9
    
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Adcock JM, Sidow SJ, Looney SW, Liu Y, McNally K, Lindsey K, et al. Histologic evaluation of canal and isthmus debridement efficacies of two different irrigant delivery techniques in a closed system. J Endod 2011;37:544-8.  Back to cited text no. 10
    
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Pedrazzi V, Oliveira-Neto JM, Sequeira P, Fedorowicz Z, Nasser M. Hand and ultrasonic instrumentation for orthograde root canal treatment of permanent teeth. Cochrane Database Syst Rev 2008. CD006384.  Back to cited text no. 12
    
13.
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Ballullaya SV, Vemuri S, Kumar PR. Variable permanent mandibular first molar: Review of literature. J Conserv Dent 2013;16:99-110.  Back to cited text no. 15
[PUBMED]  Medknow Journal  
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Salzgeber RM, Brilliant JD. Anin vivo evaluation of the penetration of an irrigating solution in root canals. J Endod 1977;3:394-8.  Back to cited text no. 16
    
17.
Chow TW. Mechanical effectiveness of root canal irrigation. J Endod 1983;9:475-9.  Back to cited text no. 17
    
18.
Senia ES, Marshall FJ, Rosen S. The solvent action of sodium hypochlorite on pulp tissue of extracted teeth. Oral Surg Oral Med Oral Pathol 1971;31:96-103.  Back to cited text no. 18
    
19.
Vera J, Hernández EM, Romero M, Arias A, van der Sluis LW. Effect of maintaining apical patency on irrigant penetration into the apical two millimeters of large root canals: Anin vivo study. J Endod 2012;38:1340-3.  Back to cited text no. 19
    
20.
Tay FR, Gu LS, Schoeffel GJ, Wimmer C, Susin L, Zhang K, et al. Effect of vapor lock on root canal debridement by using a side-vented needle for positive-pressure irrigant delivery. J Endod 2010;36:745-50.  Back to cited text no. 20
    
21.
Ram Z. Effectiveness of root canal irrigation. Oral Surg Oral Med Oral Pathol 1977;44:306-12.  Back to cited text no. 21
    
22.
Munoz HR, Camacho-Cuadra K.In vivo efficacy of three different endodontic irrigation systems for irrigant delivery to working length of mesial canals of mandibular molars. J Endod 2012;38:445-8.  Back to cited text no. 22
    
23.
Lee SJ, Wu MK, Wesselink PR. The effectiveness of syringe irrigation and ultrasonics to remove debris from simulated irregularities within prepared root canal walls. Int Endod J 2004;37:672-8.  Back to cited text no. 23
    
24.
Sabins RA, Johnson JD, Hellstein JW. A comparison of the cleaning efficacy of short-term sonic and ultrasonic passive irrigation after hand instrumentation in molar root canals. J Endod 2003;29:674-8.  Back to cited text no. 24
    
25.
van der Sluis LW, Vogels MP, Verhaagen B, Macedo R, Wesselink PR. Study on the influence of refreshment/activation cycles and irrigants on mechanical cleaning efficiency during ultrasonic activation of the irrigant. J Endod 2010;36:737-40.  Back to cited text no. 25
    
26.
Izu KH, Thomas SJ, Zhang P, Izu AE, Michalek S. Effectiveness of sodium hypochlorite in preventing inoculation of periapical tissues with contaminated patency files. J Endod 2004;30:92-4.  Back to cited text no. 26
    
27.
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. 27
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2]


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