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ORIGINAL ARTICLE
Year : 2016  |  Volume : 7  |  Issue : 2  |  Page : 83-86

Comparative histological and morphometric analysis of the effectiveness of manual and different recently introduced rotary instruments: An in vitro study


Department of Conservative Dentistry and Endodontics, National Dental College and Hospital, Dera Bassi, Punjab, India

Date of Submission29-Dec-2015
Date of Acceptance29-Mar-2016
Date of Web Publication16-Nov-2016

Correspondence Address:
Saloni Gupta
National Dental College and Hospital, Dera Bassi, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-6944.194208

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  Abstract 

Aims: The aim of this study is to evaluate cleaning efficacy of K-file, ProTaper Next, and V-Taper file systems by histological and morphometric analysis.
Subjects and Methods: Thirty extracted, single rooted human mandibular premolars were selected. The teeth were randomly divided into three groups with ten teeth each. In Group 1 teeth were prepared with K-file, in Group 2 with ProTaper Next rotary system, and Group 3 with V-Taper rotary system. Histological and morphometric analysis of specimen were done and observed under an optic microscope.
Statistical Analysis Used: The data were statistically analyzed using nonparametric analysis of variance Kruskal-Wallis test and the level of significance was set at P < 0.05. SPSS version 12 software was used for statistical analysis.
Results: Instrumentation with stainless steel K-files showed minimum amount of debris, followed by ProTaper Next files, and rotary V-Taper files were least effective with the maximum amount of debris; however, there were no significant differences between the three experimental groups.
Conclusions: Both the manual and rotary instrumentation are relatively efficient in cleaning the apical third of the root canal system, and the choice between manual and rotary instrumentation should depend on case to case basis.

Keywords: Apical third, cleaning efficiency, debris, ProTaper Next, V-Taper


How to cite this article:
Krishan S, Gupta S. Comparative histological and morphometric analysis of the effectiveness of manual and different recently introduced rotary instruments: An in vitro study. Indian J Oral Sci 2016;7:83-6

How to cite this URL:
Krishan S, Gupta S. Comparative histological and morphometric analysis of the effectiveness of manual and different recently introduced rotary instruments: An in vitro study. Indian J Oral Sci [serial online] 2016 [cited 2017 Jul 26];7:83-6. Available from: http://www.indjos.com/text.asp?2016/7/2/83/194208


  Introduction Top


Endodontic therapy involves treating vital and necrotic dental pulps so that patients can regain the function and esthetics of their natural teeth. This is essential because preparation determines the efficacy of all subsequent procedures that includes mechanical debridement, creation of space for medicament delivery, and optimized canal geometries for adequate obturation. Unfortunately, canal preparation is adversely influenced by the highly variable root canal anatomy and the relative inability of the operator to visualize this anatomy from radiographs. Hence, root canal preparation is not only important but also demanding for the clinician.

Despite the advances made in instruments and instrumentation techniques, the design and the physical limitations of the endodontic instruments can lead to inadequate cleaning of the root canal system.[1] Shaping procedures can be completed more easily, quickly, and predictably using nickel-titanium (NiTi) rotary instruments, but the effective cleansing of the root canal system, especially in the apical one-third, has not yet been demonstrated.[2],[3],[4] Both manual and mechanical instrumentation leave debris in the root canal space.[5],[6] The introduction of various rotary instruments and paucity of studies comparing hand and rotary instruments prompted us to carry out this study. The aim of this study is to evaluate cleaning efficacy of K-file, ProTaper Next, and V-Taper file systems by histological and morphometric analysis.


  Subjects and Methods Top


Thirty-three extracted, single-rooted human mandibular first premolars with single canal and completely formed roots were selected and placed in 3% sodium hypochlorite for 30 min and then stored in normal saline. The teeth were randomly divided into three groups of 10 teeth each. Three teeth were used as negative controls in which no procedure was carried out. Conventional access was made, and working length was determined 0.5 mm short of the apical foramen using #10 K-file.

Group 1

Teeth were prepared by crown down technique with stainless steel K-file (MANI INC, Tochigi, Japan) until #40 file reached the working length.

Group 2

Teeth were prepared with ProTaper Next rotary files with rectangular off-center cross-section design for greater strength and unique asymmetric rotary motion that further enhances ProTaper canal shaping efficiency with gentle in and out motion (Dentsply Maillefer, Ballaigues, Switzerland) at the working length up to X2 according to the manufacturer's instructions using an endodontic engine (X-Smart; Dentsply Maillefer, Ballaigues, Switzerland) at 300 rpm at 4-5.2 Ncm torque.

Group 3

Teeth were prepared with V-Taper rotary files (Guidance Endo, Albuquerque, New Mexico, USA) up to V (08) consisting of variable taper files made of a modified NiTi alloy called Endonol according to the manufacturer's instructions using an endodontic engine (X-Smart; Dentsply Maillefer, Ballaigues, Switzerland) at 250 rpm.

Teeth were irrigated 1 mm short of the working length with 2 ml of distilled water after the use of each instrument, and 10 ml of distilled water was used as final flush. Irrigation was performed using 30-G Max-i-probe needle (Dentsply Rinn, Elgin, IL, USA).

The apical third of each root was sectioned transversally and stored in 10% formalin for 12 h till histological processing. The samples were then washed, decalcified with 10% nitric acid, and embedded in paraffin. Three cross-sections (5 μm) were randomly obtained from each tooth. A total of 99 sections were obtained and stained with hematoxylin and eosin. The cross-sections were examined with an optic microscope (×40) coupled to a computer. After the count of the points in the clean area and the debris area, the percentage of debris in the root canal at the apical third was calculated.

The data were statistically analyzed using nonparametric analysis of variance Kruskal-Wallis test and the level of significance was set at P < 0.05. SPSS version 12 software (IBM Corp. Armonk, NY) was used for statistical analysis.


  Results Top


All the instrumentation techniques were relatively efficient in debriding the apical one-third of the root canal system. Stainless steel K-files showed the least amount of debris, followed by ProTaper Next files, and the group instrumented with V-Taper files [Figure 1]. There were no statistically significant differences between the three experimental groups [Table 1].
Figure 1: Histological analysis

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Table 1:Statistical analysis

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  Discussion Top


Chemomechanical preparation is the key to successful endodontic treatment. Its objective is to clean the root canal and its ramifications as thoroughly as possible, creating ideal conditions for tissue regeneration and health. All the instrumentations of the pulp space leave debris in the root canal.[6],[3],[7] This debris increases the risk of bacterial contamination which may lead to the failure of endodontic treatment.[8] Debris may be compacted along the entire length of the canal surface and results in reduced adaptation of sealer and gutta-percha.

In this study, histological evaluation revealed that stainless steel K-files showed better cleaning efficiency with the least amount of debris, followed by ProTaper Next files, and V-Taper files were least effective with the maximum amount of debris. The results indicated that manual instrumentation appeared superior to rotary instrumentation for the debridement in the apical third of the root canal system, but this difference did not reach statistical significance. This observation is in agreement with that of other studies.[9],[10],[11],[12] Considering the major objective of the present investigation, irrigation was performed with distilled water, avoiding any associations of different irrigation solutions. All the three groups failed to produce completely clean canals.

In addition, it was observed that some areas were uninstrumented, indicating that complete canal instrumentation was not achieved. Moreover, an irregular secondary dentine is associated with the physiological aging of the root[13] so that surface morphology, especially in the apical region, is far from smooth.[14] This could contribute to higher debris scores in the apical third of the canal.

The group instrumented with stainless steel K-files produced the least amount of debris, which could be attributed to the 0.02 taper. Lumley suggested that 0.02 taper instruments allow greater apical debridement when compared to greater taper instruments. When instrumentation is performed with files of greater taper, a false sense of tightness is created due to coronal binding of the flutes, but the apical part of the file may be lying passively within the canal.[15]

Enlargement of wide canals using ProTaper Next files resulted in 43-49% uninstrumented canal walls.[16] ProTaper instruments have multiple and progressively changing tapers along the length of their cutting blades, which reduce the contact area between the dentin and the file.[17],[18] This may have resulted in less area of the walls planned and greater debris scores. Debris area measurements were slightly greater for the canals instrumented with NiTi instruments. NiTi rotary instruments, due to their superelastic property, are not suitable for the exertion of lateral pressure, therefore leaving many areas untouched by the instrument in oval-shaped canals. Stainless steel instruments are stiffer than NiTi instruments and can be easily forced with less risk toward the root canal walls and the polar recesses following the natural canal shape and prepare the root canal walls. Better cleaning efficiency of hand instrumentation may be due to the fact that increased number of rotations in apical one-third is produced with rotary as compared to manual technique which may also have resulted in increased debris with rotary technique.

When an instrument is engaged toward its apical extent, greater torsional forces exist because of the distance between the torque generator (handle) and the resulting working torque at the apical extent of the file.[19],[20] Torque controlled handpiece auto reverses in the canal when it binds in the apical one-third and begins to rotate backward the standard two revolutions and then reverts to the original direction of rotation. It is important to be aware of this occurrence to remove the file from the tooth to clean the debris from the flutes.[21] This may be attributable to the deposition of debris in the apical one-third. It was our impression that the rotary instrumentation with ProTaper Next and V-Taper files was less time consuming than the stainless steel K-files. This is beneficial for cleaning of the root canal, increasing the time of contact between the irrigants and their substrate.[22] It has to be taken into consideration that the cleaning efficiency of the different instruments might be further improved using a combination of NaOCl and EDTA solutions. Apart from instrumentation and instrumentation techniques, other factors such as the amount of root canal wall, irrigating regimens, and curvature of the canal play a significant role in cleaning and shaping. Factors to be considered for the selection of instruments should be based on speed and ease of use, canal shaping ability, reduced apical transportation, and the reliability of instrument under mechanical stress. The choice between manual, rotary, and combination instrumentation techniques has to be made by the operator on a case to case basis, avoiding a generalized protocol.


  Conclusions Top


Both the manual and rotary instrumentation are relatively efficient in cleaning the apical third of the root canal system, and the choice between manual and rotary instrumentation should depend on case to case basis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Hülsmann M, Rümmelin C, Schäfers F. Root canal cleanliness after preparation with different endodontic handpieces and hand instruments: A comparative SEM investigation. J Endod 1997;23:301-6.  Back to cited text no. 1
    
2.
Siqueira JF Jr., Araújo MC, Garcia PF, Fraga RC, Dantas CJ. Histological evaluation of the effectiveness of five instrumentation techniques for cleaning the apical third of root canals. J Endod 1997;23:499-502.  Back to cited text no. 2
    
3.
Ahlquist M, Henningsson O, Hultenby K, Ohlin J. The effectiveness of manual and rotary techniques in the cleaning of root canals: A scanning electron microscopy study. Int Endod J 2001;34:533-7.  Back to cited text no. 3
    
4.
Gambarini G, Laszkiewicz J. A scanning electron microscopic study of debris and smear layer remaining following use of GT rotary instruments. Int Endod J 2002;35:422-7.  Back to cited text no. 4
    
5.
Hülsmann M, Stryga F. Comparison of root canal preparation using different automated devices and hand instrumentation. J Endod 1993;19:141-5.  Back to cited text no. 5
    
6.
Heard F, Walton RE. Scanning electron microscope study comparing four root canal preparation techniques in small curved canals. Int Endod J 1997;30:323-31.  Back to cited text no. 6
    
7.
Barbizam JV, Fariniuk LF, Marchesan MA, Pecora JD, Sousa-Neto MD. Effectiveness of manual and rotary instrumentation techniques for cleaning flattened root canals. J Endod 2002;28:365-6.  Back to cited text no. 7
    
8.
Nair PN, Sjögren U, Krey G, Kahnberg KE, Sundqvist G. Intraradicular bacteria and fungi in root-filled, asymptomatic human teeth with therapy-resistant periapical lesions: A long-term light and electron microscopic follow-up study. J Endod 1990;16:580-8.  Back to cited text no. 8
    
9.
Kochis KA, Walton RE, Lilly JP, Ricks L, Rivera EM. A histologic comparison of hand and NiTi rotary instrumentation techniques. J Endod 1998;24:286.  Back to cited text no. 9
    
10.
Schäfer E, Schlingemann R. Efficiency of rotary nickel-titanium K3 instruments compared with stainless steel hand K-Flexofile. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth. Int Endod J 2003;36:208-17.  Back to cited text no. 10
    
11.
Foschi F, Nucci C, Montebugnoli L, Marchionni S, Breschi L, Malagnino VA, et al. SEM evaluation of canal wall dentine following use of Mtwo and ProTaper NiTi rotary instruments. Int Endod J 2004;37:832-9.  Back to cited text no. 11
    
12.
Schäfer E, Vlassis M. Comparative investigation of two rotary nickel-titanium instruments: ProTaper versus RaCe. Part 1. Shaping ability in simulated curved canals. Int Endod J 2004;37:229-38.  Back to cited text no. 12
    
13.
Wakabayashi H, Matsumoto K, Nakamura Y, Shirasuka T. Morphology of the root canal wall and arrangement of underlying dentinal tubules. Int Endod J 1993;26:153-8.  Back to cited text no. 13
    
14.
Blum JY, Machtou P, Ruddle C, Micallef JP. Analysis of mechanical preparations in extracted teeth using ProTaper rotary instruments: Value of the safety quotient. J Endod 2003;29:567-75.  Back to cited text no. 14
    
15.
Lumley PJ. Cleaning efficacy of two apical preparation regimens following shaping with hand files of greater taper. Int Endod J 2000;33:262-5.  Back to cited text no. 15
    
16.
Peters OA, Peters CI, Schönenberger K, Barbakow F. ProTaper rotary root canal preparation: Effects of canal anatomy on final shape analysed by micro CT. Int Endod J 2003;36:86-92.  Back to cited text no. 16
    
17.
Suffridge CB, Hartwell GR, Walker TL. Cleaning efficiency of nickel-titanium GT and 0.04 rotary files when used in a torque-controlled rotary handpiece. J Endod 2003;29:346-8.  Back to cited text no. 17
    
18.
Loizides AL, Kakavetsos VD, Tzanetakis GN, Kontakiotis EG, Eliades G. A comparative study of the effects of two nickel-titanium preparation techniques on root canal geometry assessed by microcomputed tomography. J Endod 2007;33:1455-9.  Back to cited text no. 18
    
19.
Schäfer E, Lohmann D. Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile - Part 2. Cleaning effectiveness and instrumentation results in severely curved root canals of extracted teeth. Int Endod J 2002;35:514-21.  Back to cited text no. 19
    
20.
Bechelli C, Zecchi Orlandini S, Colafranceschi M. Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus lightspeed instrumentation. Int Endod J 1999;32:484-93.  Back to cited text no. 20
    
21.
West J. Progressive taper technology: Rationale and clinical technique for the new ProTaper universal system. Dent Toy 2006;25:64, 66-9.  Back to cited text no. 21
    
22.
Pasqualini D, Scotti N, Tamagnone L, Ellena F, Berutti E. Hand-operated and rotary ProTaper instruments: A comparison of working time and number of rotations in simulated root canals. J Endod 2008;34:314-7.  Back to cited text no. 22
    


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