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Evaluation of Irrigant Penetration Depth of Varying Tapers Using Single Rotary System in Curved Mandibular Molars--An In Vitro Study.

Introduction

Successful endodontic therapy requires shaping and cleaning of the root canal system and is performed using root canal instruments and irrigating solutions [1, 2]. However, it was shown that the canal preparation is influenced by the great variability of root canal anatomy. Indeed, the instruments (both manual and rotary) do not reach certain areas such as cracks, crevices, isthmus, accessory canals and apical deltas [3, 4]. So, instrumentation alone is inadequate for disinfection of root canals in the majority of cases, necessitating the addition of chemical irrigation [5, 6].

Several irrigation agents have been developed in response to chemical disinfection. However, sodium hypochlorite (NaOCl) remains the irrigant of choice [7-9] due to its antibacterial nature, dissolving both necrotic and organic matter within the smear layer [10]. Currently, a final irrigation sequence is combination of EDTA and NaOCL to remove inorganic and organic components of root canal [11].

Salzgeber and Brilliant reported that SL and debris removal is less predictable in the apical region as compared with the coronal and middle third of the root [12]. This can be due to comparatively smaller apical canal dimensions making it difficult to contact between canal walls and the irrigants [13]. Bronnec et al [14] reported that improved shaping of the root canals enhanced the flow of irrigants. On the other hand, minimal apical enlargement has been suggested to conserve tooth structure and limit extrusion of filling materials [15].

The extent of apical enlargement, however, has been a matter of debate. A common recommendation is to enlarge the root canal to at least three sizes beyond the initial file [16]. Effects of various sizes and tapers including 20.10 [16], 30.04 [17], 30.06 [18], or 40.04 [19] on debridement of apical debris have been evaluated and reported.

Aim of the study is to evaluate the irrigant penetration depth of varying tapers using m-two files in curved mesiobuccal canals.

Materials and Methods

A total of 30 Mandibular molars with curved mesial roots extracted for periodontal reasons were stored in distilled water at 4[degrees]C until use. The root curvature was standardized according to Schneider's technique to 20-40[degrees].

All the teeth were decoronated to a length of 12mm with a tapered diamond bur using straight handpiece. A flat surface for easier access to the pulp chamber and to facilitate length measurement of the canal.

Standard Endodontic access cavities were prepared and the selected curved canals were explored with a pre-curved #8 Kfile. The working length was estimated by advancing this file passively into the root canal until the tip of the file was seen at the apical foramen. This was done by using the Heine HR 2.5x High Resolution Binocular Loupes with LED, working length was determined by subtracting 0.5 mm from this measurement (Fig 1).

Thirty root canals were selected, and working length was determined. The molars were randomly assigned to 3 experimental groups of 10 canals each. The canals were instrumented using M-two rotary files (VDW Gmbh) and motor controller device (X-SMART, Dentsply, Maillefer, Ballaigues, Switzerland) according to the manufacturer's instructions in the ordered sequence. Group 1: 35.04% (Fig 2). Group 2: 25.06% (Fig 3). Group 3: 20.06% (Fig 4). In each group the last instrument was considered the MAF.

After each rotary file, the canal was rinsed with 2ml of 3% NaOCl, delivered by 28-guage needles (Max I-probe, Franklin Park, IL, USA) inserted deeply and passively from coronal to middle third at the end of coronal pre-flaring. During the apical preparation sequence, the needle penetrated within the apical 3mm. Finally, the specimens were rinsed with 2 ml of 17% EDTA followed by 2 ml of 5.25% NaOCl each for 60s. Final flushing with 5 ml of distilled water was done to eliminate the irrigation solutions from the canals.

Measurement of irrigant penetration depth

28-guage needles (Max I-probe, Franklin Park, IL, USA) inserted 3mm short of apex in all the groups. Iohexol, radiopaque dye was delivered passively and irrigant penetration depth was measured using occlusal photo stimulable phosphor radiographs. The measurement was done using digital analogue scale from coronal to apical direction.

Statistical Analysis

Statistical analysis was performed using the ANOVA test among all the groups. Post-hoc tukey HSD test was used for multiple comparisons at 95% confidence interval and P=0.05.

Results

The results showed statistically significant differences in the irrigant penetration depth among the groups. Group 1 and 3 & 2 and 3 showed statistically significant difference in irrigant penetration depth. Group 1 and 2 doesn't have significant difference [Table 1].

No deformity or separation of rotary files, and no occurrence of apical perforations were seen during this study.

Discussion

Results of this study showed significant differences between groups 35.04 and 20.06 & 25.06 and 20.06. There were no significant differences between 35.04% and 25.06%. These groups showed acceptable debridement. Our findings showed that increased size and taper of MAF at WL improved irrigant penetration depth.

In the present study, mesio buccal canals of mandibular molars with a similar root curvature (20[degrees]-40[degrees]) were prepared using mtwo rotary files. Mohammadzadeh Akhlaghi et al, used the same curvature with m-two rotary files [20].

Khademi et al also showed that MAF # 30.06 was effective for the removal of debris and SL from the apical portion of root canals [18]. On the other hand, instrumentation to 30.06 caused less dentin removal and decreased the risk of errors like transportation, ledge formation, instrument separation and perforation [16].

Akhlaghi et al showed that V Taper # 30.10 maintained the canal centering and minimum root thickness in the apical part of curved canals [21]. Brunson et al reported that root canal preparation by using K3 rotary instruments to size 40.04 will allow for tooth structure preservation and maximum volume of irrigation at the apical third of single-rooted teeth when using the apical negative pressure irrigation system [19].

Wu and Wesselink have recommended enlarging the canals to sizes over # 40 file to remove more debris from the canals and achieve better cleaning in the apical thirds of the root canals [22].

Albrecht et al instrumented the canals with various tapers of ProFile GT files and observed a significantly greater percentage of remaining debris in the apical areas of the canals enlarged to the size 20 compared to 40 in the .04, .06 and .08 taper categories; however when the taper was increased to .10 no significant difference was found between the sizes 20 and 40. Although the results showed that increasing the taper from .04 to .06 in file #30 led to more SL removal, it caused no statistical significance in debris removal [16].

This finding is supported by Arvaniti and Khabbaz who reported that root canal taper can affect debridement only when the final instrument size was smaller than 30 [17].

According to some previous studies, file 30.06 may be considered as the minimum size for acceptable debridement, in this present study, 25.06 & 35.04 showed good irrigant penetration depth in curved mandibular molars.

Conclusion

We conclude that apical enlargement plays a major role in the penetration of irrigant to the apical third, rendering complete canal debridement. From the results 35.04% and 25.06% taper file showed complete irrigant penetration depth & 20.06% taper file does not render complete debridement of curved mesiobuccal canal.

References

[1.] Hales JJ, Jackson CR, Everett AP, Moore S. Treatment protocol for the management of a sodium hypochlorite accident during endodontic therapy. Gen Dent. 49:278-81 (2001).

[2.] Lumley PJ. Cleaning efficacy of two apical preparation regimens following shaping with hand files of greater taper. Int Endod J. 33(3):262-5 (2000).

[3.] Peters OA. Current challenges and concepts in the preparation of root canal systems: a review. J Endod 30:559-67 (2004).

[4.] Tronstad L. Endodontie clinique. Paris: Flammarion Me'decine; 235 (1995).

[5.] Bystrom A, Sundqvist G. Bacteriologic evaluation of the effect of mechanical instrumentation in endodontic therapy. Scand J Dent Res 89: 321-8. 2 (1981).

[6.] Bystrom A, Sundqvist G. Bacteriologic evaluation of the effect of 0.5% sodium hypochlorite in endodontic therapy. Oral Surg Oral Med Oral Pathol 55:307-12 (1983).

[7.] Boutsioukis, T. Lambrianidis, E. Kastrinakis, and P. Bekiaroglou, "Measurement of pressure and flow rates during irrigation of a root canal ex vivo with three endodontic needles," International Endodontic Journal, vol. 40, no. 7, pp. 504-513 (2007).

[8.] N. Juneja and M. N. Hegde, "Comparison of the antifungal efficacy of 1.3% NaOCl/MTAD with other routine irrigants: an ex-vivo study," International Scholarly Research Notices, Article ID 575748, 5 pages (2014).

[9.] A. Azhar Iqbal, "Antimicrobial irrigants in the endodontic therapy," International Journal of Health Sciences, vol. 6, no. 2, pp. 186-192 (2012).

[10.] M. C. Valera, F. G. D. R. Cardoso, A. Chung et al., "Comparison of different irrigants in the removal of endotoxins and cultivable microorganisms from infected root canals," The Scientific World Journal, Article ID 125636, 6 pages (2015).

[11.] Zehnder M. Root canal irrigants. J Endod. 32(5):389-98 (2006).

[12.] Salzgeber RM, Brilliant JD. An in vivo evaluation of the penetration of an irrigating solution in root canals. J Endod. 3:394-8 (1997).

[13.] Senia ES, Marshall FJ, Rosen S. The solvent action of sodium hypochlorite on pulp tissue of extracted teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 31:96-103 (1971).

[14.] Bronnec F, Bouillaguet S, Machtou P. Ex vivo assessment of irrigant penetration and renewal during the cleaning and shaping of root canals: a digital subtraction radiographic study. Int Endod J.43:275-82 (2010).

[15.] Buchanan LS. The standardized -taper root canal preparation-Part 3. GT file technique in large root canals with small apical diameters. Int Endod J. 34:149-56 (2001).

[16.] Albrecht LJ, Baumgartner JC, Marshall JG. Evaluation of apical debris removal using various sizes and tapers of profile GT files. J Endod. 30(6):425-8 (2004).

[17.] Arvaniti IS, Khabbaz MG. Influence of root canal taper on its cleanliness: a scanning electron microscopic study. J Endod. 37(6):871-4 (2011).

[18.] 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.;32(5):417-20. (2006).

[19.] Brunson M, Heilborn C, Johnson D, Cohenca N. Effect of apical preparation size and preparation taper on irrigant volume delivered by using negative pressure irrigation system. J Endod.36(4):721-4 (2010).

[20.] Mohammadzadeh Akhlaghi N, Behrooz E, Saghiri MA. Efficacy of MTAD, Glyde and EDTA in debridement of curved root canals. Iranian Endod J.4(2):58-62 (2009)

[21.] Akhlaghi NM, Kahali R, Abtahi A, Tabatabaee S, Mehrvarzfar P, Parirokh M. Comparison of dentine removal using V-taper and KFlexofile instruments. Int Endod J.43:1029-36 (2010).

[22.] Wu MK, Wesselink PR. Efficacy of three techniques in cleaning the apical portion of curved root canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod.79:492-6 (1995).

S. Deepak, M.S. Nivedhitha

Department of Conservative Dentistry & Endodontics, Saveetha Dental College, Saveetha University, 162, Poonamallee High Road, Chennai 600077, India

Received 22 April 2017; Accepted 11 November 2017; Published online 31 December 2017

* Coresponding author: Dr. S. Deepak;

E-mail: sdeepu.92@gmail.com

Caption: Figure 1:

Caption: Figure 2:

Caption: Figure 3:

Caption: Figure 4:

Caption: Figure 5:
Table 1: Comparison of irrigant penetration depth among 35.05%,
25.06% and 20.06% tapers (Post-hoc turkey HSD test)

    Comparison      Mean        STD     Significance
      within     Difference    Error
      groups

1     25.06        0.290      0.41634      0.768
      20.06       2.000 *     0.41634      0.000
2     35.04        -0.200     0.41634      0.768
      20.06       1.710 *     0.41634      0.001
3     35.04       -2.000 *    0.41634      0.000
      25.06       -1.710 *    0.41634      0.001

    Comparison     95% Confidence
      within           Interval
      groups
                 Lower     upper
                 Bound     Bound

1     25.06      -0.7423   1.3223
      20.06      0.9677    3.0323
2     35.04      -1.3223   0.7423
      20.06      0.6777    2.7423
3     35.04      -3.0323   -0.9677
      25.06      -2.7423   -0.6777

Figure 6:

Group 1   10.48
Group 2   10.19
Group 3   18.481

Note: Table made from bar graph.
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Title Annotation:Original Article
Author:Deepak, S.; Nivedhitha, M.S.
Publication:Trends in Biomaterials and Artificial Organs
Date:Apr 1, 2017
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