|Year : 2015 | Volume
| Issue : 1 | Page : 35-38
Efficiency of a semiconductor diode laser in disinfection of the root canal system in endodontics: An in vitro study
Mithra N Hegde, Raksha Bhat, Preethesh Shetty
Department of Conservative Dentistry and Endodontics, Attavar Balakrishna Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka, India
|Date of Web Publication||18-Mar-2015|
Dr. Raksha Bhat
Department of Conservative Dentistry and Endodontics, Attavar Balakrishna Shetty Memorial Institute of Dental Sciences, Nitte University, Deralakatte, Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Context: The success of endodontic treatment depends on the eradication of microbes from the rootcanal system and prevention of reinfection. The root canal is shaped with hand and rotary instruments under constant irrigation to remove the inflamed and necrotic tissue, microbes/biofilms, and other debris from the root canal space. The main goal of instrumentation is to facilitate effective irrigation, disinfection, and filling. Throughout the history of endodontics, endeavors have continuously been made to develop more effective irrigant delivery and agitation systems for root canal irrigation. Aim: The purpose of this study was to evaluate the efficacy of three different newer irrigation delivery techniques; namely Endovac, Stropko Irrigator, and laser disinfection with 5.25% sodium hypochlorite. Materials and Methods: Forty teeth after disinfection by Occupational Safety and Health Administration (OSHA) regulations were instrumented and inoculated with bacterial strains of Enterococcusfaecalis. The teeth were divided into four groups, in the experimental group, the irrigants were delivered with the Endovac, Stropko Irrigator, and laser irradiation and the control group which received no irrigation. The samples were incubated in Muller-Hilton media plates and incubated for 24 h. Statistical analysis used: The colony forming units were determined and statistically analyzed using the chi-square test. Results: According to the results obtained, laser irradiation resulted in complete disinfection of the root canal system. The Endovac system resulted in significant disinfection as compared to the Stropko Irrigator system. Conclusion: Laser irradiation resulted in significantly higher antimicrobial effects compared with the Endovac and Stropko irrigation groups when in conjunction with sodium hypochlorite
Keywords: Disinfection, endovac, irrigation, lasers, stropko irrigator
|How to cite this article:|
Hegde MN, Bhat R, Shetty P. Efficiency of a semiconductor diode laser in disinfection of the root canal system in endodontics: An in vitro study. J Int Clin Dent Res Organ 2015;7:35-8
|How to cite this URL:|
Hegde MN, Bhat R, Shetty P. Efficiency of a semiconductor diode laser in disinfection of the root canal system in endodontics: An in vitro study. J Int Clin Dent Res Organ [serial online] 2015 [cited 2019 Apr 18];7:35-8. Available from: http://www.jicdro.org/text.asp?2015/7/1/35/153493
| Introduction|| |
Root canal therapy involves removal of vital and necrotic pulp, infected dentin, and debris to eliminate microorganisms. ,, Enterococcus faecalis endures chemomechanical instrumentation and intracanal medication to proceed to remain viable within the dentinal tubules. , Hence, efficient delivery systems such as the Endovacm, Stropko Irrigator, and Diode lasers ,, have been developed.
Combination therapy using irrigation solutions together or in succession has been reported to be more effective for canal disinfection.  The purpose of this study was to evaluate the efficacy of different irrigation delivery systems in combination with 5.25% NaOCl in disinfection of the root canal.
| Materials and Methods|| |
Forty noncarious mandibular premolar teeth extracted for orthodontic purpose, were selected for the study. The presence of a single canal was determined radiographically with digital radiographs taken at different angulations. The teeth with open and resorbed apices, grossly carious teeth, and teeth with fractured roots were excluded from the study. The teeth were disinfected according to Occupational Safety & Health Administration (OSHA) regulations, 2004. Crowns of the teeth were transversally removed with high speed diamond disc. Working length was determined with the help of digital radiograph and prepared by serial preparation to a #30 K file, with saline as an irrigant; for easier inoculation of bacteria. Two coats of nail varnish were applied to seal the apex. The canals were dried with paper points and sterilization was achieved by gamma irradiation.  The teeth were inoculated with bacterial strains of E. faecalis (ATCC 29212) and the teeth were incubated for 24 h. A suspension of 50 μL of E. faecalis strand was incubated in 5 mL of brain heart infusion broth culture medium in 37°C incubator for 24 h. The concentration of inoculation was then adjusted for a degree of turbidity according to McFarland scale which corresponds to bacterial concentration of 3 × 10 8 cells/ml, and corresponding to optic density of 550 nm. The root canals were filled with inoculation and were incubated for 21 days at 37°C in an incubator. All samples had a portion of inoculation transferred in 5% sheep blood Trypticase Soy Agar (TSA) plates to check E. faecalis bacterial growth at several time periods, with a result of 100% positive. After incubation, the contaminated roots were randomly divided into four groups (n = 10) according to the disinfection regimen used.
Teeth were randomly divided into four groups; all 40 samples were inoculated with E. faecalis for 24 h at 37°C and all the steps were conducted under sterile conditions. The first group of 10 samples served as the control group; the second, third, and the fourth group; the experimental group each containing 10 samples each.
Group I: (n = 10)
This group comprised of the teeth which were cleaned and shaped, inoculated with strains of E. faecalis, but no irrigation was done. This group served as the control group.
Group II: (n = 10)
The teeth were irrigated with the Endovac irrigation system. Macroirrigation was performed with 5.25% sodium hypochlorite, while the macrocannula was constantly moved up and down from its point of apical restriction to just below the canal orifice. This step was accomplished in 30 s. Sodium hypochlorite was then left in the canal untouched for 60 s. This was followed by three cycles of microirrigation of 30 s each, while the microcannula was moved up and down the full working length. 
Group III: (n = 10)
The teeth were irrigated with the Stropko Irrigator system. Irrigation was performed after attaching the Stropko Irrigator to the air/water syringe. The canal was flooded with 5.25% sodium hypochlorite and it was activated with the help of an endoactivator which is known to produce a tsunami effect causing flushing action in the canal. The canal is then reflooded with sodium hypochlorite and then the fluid is evacuated. Air pressure to air/water syringe must be properly regulated, it is usually 30-50 lbs. For air-drying in endodontic canals, it must be reduced to 1-3 lbs.
Group IV: (n = 10)
The teeth were disinfected with the diode laser. The irrigant was deposited into the canal with a 27 gauge needle. Intracanal irradiation was performed using a high power 908 nm diode laser (Kavo Gentle Ray) with a 200 μm fiberoptic tip and set at a power of 2.5 W. Using an oscillatory technique, the diode fiber (200μm fiberoptic tip) was introduced 1 mm short of the apex and recessed in helicoidal movements at a speed of approximately 1 mm/s, and repeated four times at intervals of 10 s between each one. 
After disinfection, paper points were used to collect the samples from the teeth and were placed in brain heart infusion broth in microtubes and incubated for 24 h. The samples in the microtubes were transferred to the Petri dish More Detailses containing Muller-Hilton diffusion media using a nichrome wire loop and incubated for 24 h.
The results obtained were statistically analyzed using the chi-square test.
| Results|| |
The mean CFU for all groups were: Group 1 = 10 8 per ml, Group 2 = 10 3 per ml, Group 3 =10 5 per ml, and Group 4 = 0. Statistical analysis demonstrated statistically significant differences between the laser irradiated group (Group 4) and the Endovac and Stropko group (Groups 2 and 3, respectively), and control group (P < 0.05) [Figure 1].
|Figure 1: The following bar diagram depicts the colony forming units of bacteria observed when using different irrigation techniques|
Click here to view
The degree of disinfection for experimental groups, in relation to Group 1-control, which presented total contamination; Group 4 demonstrated 100% disinfection; and Groups 2 and 3 demonstrated 50 and 20% disinfection, respectively.
| Discussion|| |
Microorganisms in the root canals have been long recognized as the primary etiological factors in the development of pulp and periapical lesions.  It is necessary to chemically debride the teeth with complex internal anatomy or other irregularities that might be missed by instrumentation of the root canals. In the present study, 5.25% sodium hypochlorite solution was used as an irrigant as it is known to have potent antimicrobial action and also have powerful oxidative activity. E. faecalis (ATCC 29212) was used as a test organism as it is commonly associated with root canal failure cases and persistent apical periodontitis. They also have the ability to reside inside the canals without the support of other microorganisms and under specific conditions have the ability to infect the whole length of tubules within days. 
A study done by Manikandan et al., concluded that E. faecalisforms biofilm at various pH (7.3-12.3) and sodium hypochlorite have greater antimicrobial effect than chlorhexidine on E. faecalis biofilm.  The effectiveness and safety of irrigation depends on the means of delivery; hence an increasing number of novel needle-tip designs and equipment are emerging in an effort to better address the challenges of irrigation. In the recent times, lasers have shown great promise in the field of endodontics and studies have demonstrated the bactericidal effects of diode laser in root canal disinfection. Moritz et al., has reported that an 890 nm diode laser was able to disinfect the root canal walls.  However in the present study, wherein a 980 nm diode laser was used in conjunction with 5.25% sodium hypochlorite; the reduction in the colony forming units was found to be significantly reduced as compared to the control group.
The results of the present study are in accordance with the studies done by Thomas et al., Castelo-Baz et al., and Mithra et al., which concluded that the diode used in conjunction with conventional chemomechanical techniques demonstrated a significant elimination of E. faecalisin the root canals. ,, The superior bactericidal effect of diode laser irradiation could be attributed to its greater depth of penetration (up to 1,000 μm into dentinal tubules) when compared to the penetration power of chemical disinfectants, which is limited to 100 μm.  It has been found that with progressive decrease in diameter of the deep dentinal tubules, the penetration of irrigants is restricted. Laser irradiation with its inherent properties of light scattering, local intensity enhancement, and attenuation allows light penetration deeper in the dentin tubules contributing to a superior antimicrobial efficacy. 
Similar results supporting our study were obtained when Kreisler et al., (2003) investigated the bactericidal effect of a semiconductor laser used in combination with NaOCl/hydrogen peroxide (H 2 O 2 ) irrigation, or saline alone, and found that the former resulted in significant bactericidal reduction compared to the use of laser alone.  Diode laser spectrum (GaAlAs -gallium aluminum arsenide) allows for greater absorption by water in dental tissues when compared with neodymium-doped yttrium aluminium garnet (Nd: YAG) laser. This results in greater laser light penetration through dentin with little interaction with it, making it possible to act on microorganisms present in the dentinal tubules. In addition, the diode laser causes a thermal photodisruptive action in the unreachable parts of dentin, resulting in an enhanced bactericidal effect in the root canal dentin. ,,,,
According to the results of the present study; the Endovac irrigation system was also found to be effective in eliminating the bacteria from the root canals, but not as effective as the laser disinfection. Endovac is known to pull the irrigant into the canal and remove it by negative pressure at the working length, thus avoiding entrapment of air and also safely delivers irrigant until the working length. 
The present study is in accordance with the study done by Hockett et al., which concluded that the Endovac hadthe ability to remove bacteria more effectively from root canals than traditional irrigation system.  Studies by Siu and Baumgartner, Mitchell et al., have also reported that the Endovac System is safer and is more effective in cleaning the root canal especially in the apical third. , Although with Endovac there was significant reduction of the bacterial load, it is just a mechanical aid in irrigation and does not have any antibacterial properties by itself like lasers. Stropko irrigation system introduced by John Stropko is an instrument used for precise control of delivery of irrigants in any dental procedure. In the present study, we used Stropko Irrigator in conjunction with 5.25% sodium hypochlorite solution, wherein we found the colony forming units to be reduced to less than 10 5 per ml as compared to the control group where the colony forming units were more than 10 8 per ml.
| Conclusion|| |
Effective irrigant delivery is prerequisited for successful endodontic treatment. In this study, laser group resulted in significantly higher antimicrobial effects compared with the Endovac and Stropko irrigation groups when in conjunction with sodium hypochlorite. The diodelaser irradiation may be apossible supplement to existing protocols for disinfection of the root canal system as the penetrating properties of laser light may allow a bactericidal effect beyond 1 mm of dentine. However, further studies are required along with other irrigating solutions are required to determine an ideal irrigating regimen in endodontics.
| Acknowledgement|| |
We would like to acknowledge the Nitte University Central Research (NUCSER) lab for helping carry out the research work.
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