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ARTICLE Table of Contents   
Year : 2006  |  Volume : 9  |  Issue : 2  |  Page : 72-77
A comparative evaluation of the cleaning efficacy of three different agents on rotary nickel-titanium endodontic instruments- An in-vitro study


Department of Conservative Dentistry & Endodontics, Rajas Dental College and Hospital, Kavalkinaru Jn, Tirunelveli District - 627 105, India

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   Abstract 

Cleaning of endodontic instruments is important to prevent cross contamination between patients and facilitate sterilization, thus achieving the goal of three dimensional obturation. The aim of this study was to develop an effective cleaning procedure for rotary Ni-Ti instruments. New sterilized Ni-Ti rotary instruments were contaminated by preparing canals of extracted teeth and subjected to both mechanical and chemical cleaning procedures followed by placing in an ultrasonic bath. This study showed that a sequential cleaning procedure including combined mechanical and chemical removal with 2% glutaraldchyde followed by ultrasonic bath is an effective procedure of removing debris from rotary Ni- Ti instruments.

How to cite this article:
Aravind L, Kumar A, Sam JE, Ignatius RS. A comparative evaluation of the cleaning efficacy of three different agents on rotary nickel-titanium endodontic instruments- An in-vitro study. J Conserv Dent 2006;9:72-7

How to cite this URL:
Aravind L, Kumar A, Sam JE, Ignatius RS. A comparative evaluation of the cleaning efficacy of three different agents on rotary nickel-titanium endodontic instruments- An in-vitro study. J Conserv Dent [serial online] 2006 [cited 2020 Oct 30];9:72-7. Available from: https://www.jcd.org.in/text.asp?2006/9/2/72/42361

   Introduction Top


Infection control has always been a major issue in the dental office. This is especially important in endodontics since during root canal instrumentation all types of debris are encountered such as necrotic and vital tissue, bacteria, dentin chips, blood by-products and other potential irritants. The exchange of this debris via instruments from one patient to another is undesirable as these may act as antigens, infecting agents or non-specific irritants [1] . This bioburden may interfere with sterilization by forming a protective barrier that prevents complete sterilization of the surface beneath by insulating underlying organisms from the sterilizing agent. If this bioburden is not removed any sterilization procedure may prove futile [5] .

The vast majority of endodontic instruments are made of carbon steel or stainless steel. Now, a variety of hand as well as engine driven endodontic files and instruments are made of Nickel-Titanium. This "memory metal" has superior physical properties thereby making it suitable for endodontic use [10] . The Nickel-Titanium alloy was developed about 40 years ago by I3euhler et al at the Naval Ordnance Laboratory, Silver springs, Maryland. Ni-Ti files were introduced to the field of Endodontics by Walia et al in 1988. The design of the flutes in Ni-Ti files is such that they may tend to accumulate debris between the flutes in an area which is relatively inaccessible for cleaning [1] . This may increase the risk of cross contamination between patients.

The aim of our present study was to develop an effective cleaning procedure for Ni-Ti rotary instruments and evaluate the effectiveness of the following cleaning procedures:

  • Mechanical (brushing)
  • Combined mechanical and chemical techniques
  • Ultrasonic bath



   Materials and Method Top


  1. Profile (Dentsply Tulsa dental, Tulsa, OK,USA)
  2. ProTaper (Dentsply Mai I lefer, Switzerland)
  3. 2% Glutaraldehyde (Nice chemicals, Mumbai)
  4. 1 % Sodium Hypochlorite (Nice chemicals, Mumbai)
  5. 3% Hydrogen Peroxide (Rajat pharmaceuticals, Mumbai)
  6. 0.1%Chlorhexidine Gluconate solution
  7. Nylon bristle brush
  8. Ultrasonic bath(Sonorex Digitec)
  9. Van- Giesons stain
  10. Stereomicroscope (Leica microsystems, Switzerland)
  11. Distilled water


Experimental groups

Sixty new Ni-Ti instruments were used to instrument the canals of freshly extracted premolar teeth. Visual debris was noted and the instruments were inserted into a sponge soaked in 0.1% chlorhexidine gluconate solution for 30 minutes. The instruments were then randomly divided into six groups of 10 instruments(5 ProFile and 5 ProTaper) each and subjected to different cleaning procedures as follows:

Group 1

Instruments were placed in an instrument stand and the flutes were brushed with a nylon bristle brush for 20 strokes per row under running distilled water for 5 minutes.

Group 2

Instruments were brushed as in group 1 , and then placed in a graduated beaker containing 1 % Sodium Hypochlorite solution for 10 minutes and rinsed under running distilled water for 5 minutes.

Group 3

Instruments were brushed, immersed in 1% Sodium Hypochlorite for 10 minutes, placed in an ultrasonic bath for 5 minutes and rinsed under running distilled water for 5 minutes.

Group 4

Instruments were brushed, immersed in 3% Hydrogen peroxide for 10 minutes and rinsed under running distilled water for 5 minutes.

Group 5

Instruments were brushed, immersed in 3% Hydrogen peroxide for 10 minutes , placed in an ultrasonic bath for 5 minutes and rinsed under running distilled water for 5 minutes.

Group 6

Instruments were brushed, immersed in 2% Glutaraldehyde for 10 minutes, placed in an ultrasonic bath for 5 minutes and rinsed under running distilled water for 5 minutes.

After the cleaning procedure was done with, the instruments were air-dried by placing in the instrument stand, followed by immersion in Van-­Gieson's stain for 3 minutes. The Ni-Ti instruments were then rinsed under running distilled water and air dried by placing it in the instrument stand.

A Stereomicroscope at 50 X was used to examine the instruments for debris at 3 levels

  • Apical
  • Middle
  • Coronal


At each level the instruments were examined on 4 sides by mounting them on an acrylic block

The residue on the flutes of the instruments were classified its

  • Stained debris
  • Unstained debris
  • Thin film


The Scoring Criteria for debris depending on the extent of stained debris was followed as described by Linsuwanont et al, (2004)4:

0-none

1 film only

2 (slight) scattered particles spaced widely apart on the flute surfaces

3 (moderate) numerous particles with areas of continuous coverage on the flute surfaces

4 (heavy) areas where the flutes are packed with debris to their entire depth

Only one category of debris was assigned to each site examined. Stained debris ranked ahead of the organic film. The organic film ranked ahead of the unstained debris


   Results Top


The results were then analyzed statistically by using Kruskal- Wallis test. According to the results Group 6(Brushing, 2% Glutaraldehyde, Ultrasonic Bath) showed a statistically significant difference compared to the other test groups.


   Discussion Top


Numerous studies have recommended the cleaning of instruments prior to the sterilization procedure between appointments.

Hubbard et al (1975) stated that plunging a file into a dry sponge followed by a saline gauze wipe removes 90 % of the micro organisms. Segall et al (1977)7 recommended chairside cleaning of endodontic instruments by using 2" x 2" inch gauze wipes. either wet with alcohol or dry. Murgel et al (1990) [1] investigated the effects of: a) a sponge soaked in alcohol b) a gauze soaked in alcohol and c) an ultrasonic bath. They found that none of these methods were able to clean the instruments totally and effectively.

The design of Ni-Ti files is such that debris accumulates between the flutes which is relatively inaccessible for cleaning. Van Gieson's stain was used in our study, since it is an effective single step staining procedure as it stains the collagen of the organic material [4] . Ultrasonic bath has the advantage of being faster and easier in cleaning dental instruments but requires care and attention both for the initial instrument preparation and for the appropriate time of usage [1] .

According to the results of our study, the combined method of

  • Mechanical brushing (Nylon bristle brush)
  • Immersion in 2 % Glutaraldehyde for 10 minutes followed by placing in
  • Ultrasonic bath for 5 minutes is the best method for removal of debris from instruments.


Glutaraldehyde (2 % )was used in this study, since it is a strong disinfectant, fixative and kills micro organisms by altering the essential protein compounds. It has been proven to be biocidal in concentrations as low as 2 % (Gravenmade & Dankert. 1975 ) [3] . It has also been reported to be non corrosive and non toxic. Sodium hypochlorite (I %) which has been previously tested for its cleaning effectiveness (Linsuwanont et al, 2004) [4] was also included in this study. It has the ability to dissolve organic materials, but its tissue dissolving ability depends on its concentration, mechanical agitation and strongly on the ratio of hypochlorite to organic matter ( Moorer W R, Wesselink P R, 1982 ) [6] . It has also been shown that with I'% Sodium hypochlorite no significant corrosion of Ni-Ti instruments was found even after an immersion time of 60 minutes [8] .

Hydrogen Peroxide was also tested in this study since it produces a transient yet energetic effervescence that displaces debris by bulk flow. The bubbling action of the solution when in contact with tissues physically foams debris Out of the canals [11] .

Endodontic files are generally cleaned at the end of each appointment or even at the end of the day. This delay in time may decrease the efficacy of debris removal once it has dried. Due to the limitations of our study. this delay factor has not been tested. Following cleaning, endodontic instruments can be sterilized by steam autoclave or dry heat before use and by glass bead or salt sterilizers at the chairside [8] . The results of our study has also shown that the mechanical removal of large quantities of debris by brushing is necessary prior to the use of chemical solutions followed by using the ultrasonic bath for better cleaning and disinfection.


   Conclusion Top


The results of our study has shown that a sequential cleaning procedure including combined mechanical and chemical removal with 2 % Glutaraldehyde followed by placing in an ultrasonic bath is an effective procedure of removing debris from rotary Ni-Ti instruments. Even this sequential procedure could not totally remove the organic debris from all the Ni-Ti instruments studied, but it considerably minimizes the biological risk prior to sterilization. If the micro organisms cannot be removed by pre - cleaning or destroyed by sterilization then the Ni-Ti files should be discarded after each use.[Table 1],[Table 2],[Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6]

 
   References Top

1.Carlos Alberto Ferreira Murgel, Richard. E.Walton, Barry Rittman, Jesus Djalma Pecora. A Comparison of Techniques for cleaning Endodontic Files after usage: A quantitative scanning electron microscopic study. J Endod 1990;16:214 217.  Back to cited text no. 1    
2.Dental Clinics of North America: Modern Endodontic Practice;2004  Back to cited text no. 2    
3.Grossman LI, Endodontic Practice, 1988:229  Back to cited text no. 3    
4.Linsuwanont, P. Parashos, H. H. Messer. Cleaning of Rotary Nickel Titanium Endodontic Instruments.lnt Endod J.2004;37:19-28  Back to cited text no. 4    
5.Mary. A. Johnson, Patrice. D. Primack, Robert. J. Loushine, David. W.Craft.C leaning of Endodontic files,Part I:The Effect of Bio burden on the Sterilization of Endodontic Files. J Endod 1997; 23:32-34  Back to cited text no. 5    
6.Moorer. W. R, Wesselink. P. R. Factors promoting the tissue dissolving Capability of Sodium Hypochloritc. lnt Endod J.1982;15:187-196.  Back to cited text no. 6    
7.Ronald. O. Segall, Carlos. E. Del Rio, William. A. Ayer. Oral Surg. 1977; 44:786 791  Back to cited text no. 7    
8.Svec.A, John. M. Powers. The deterioration of rotary nickel-titanium files under controlled conditions. J Endod 2002; 28:105-107.  Back to cited text no. 8    
9.Timothy Busslinger. A, Sener.A, F.Barbakow. Effects of sodium hypochlorite on nickel titanium Lightspeed instruments. Int Endod J 1998; 31:290-294  Back to cited text no. 9    
10.Youssef Haikel, Rene Serfaty, P. Wilson, J. M. Speisser, Claude Allemann. Mechanical properties of Nickel-Titanium Endodontic Instruments and the effect of Sodium Hypochlorite treatment.J Endod 1998; 24:731 - 735.  Back to cited text no. 10    
11.Weine, Endodontic Therapy, 1998:370  Back to cited text no. 11    

Top
Correspondence Address:
Lakshmi Aravind
Department of Conservative Dentistry & Endodontics, Rajas Dental College and Hospital, Kavalkinaru Jn, Tirunelveli District - 627 105
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-0707.42361

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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    Abstract
    Introduction
    Materials and Method
    Results
    Discussion
    Conclusion
    References
    Article Figures
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