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 Table of Contents  
Year : 2020  |  Volume : 32  |  Issue : 3  |  Page : 142-147

Comparative evaluation of different laser modalities on post endodontic pain in single visit root canal treatment: A randomized controlled trial

Department of Conservative Dentistry and Endodontics and I.T.S Dental College, Hospital and Research Centre, Greater Noida, Uttar Pradesh, India

Date of Submission03-Feb-2020
Date of Decision13-Mar-2020
Date of Acceptance14-Jun-2020
Date of Web Publication28-Oct-2020

Correspondence Address:
Dr. Anchal Aggarwal
U-5/A, Second Floor, Green Park Main, Delhi - 110 016
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_14_20

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Background: Postendodontic pain (PEP) is defined as pain of any degree that occurs after initiation of root canal treatment (RCT). The development of postoperative pain is usually due to acute inflammatory response in the periradicular tissues.
Aim: The aim of the study was to evaluate and compare the influence of different laser modalities on PEP following a single-visit RCT.
Materials and Methods: Thirty-six patients were divided into three Groups (36 = 12 × 3), Group 1, Control (Placebo); Group 2, Canal Disinfection; and Group 3, Periapical Biostimulation. A questionnaire was given at the end of the appointment to be filled at 6, 12, 24, and 48 hours using visual analog scale.
Results: Group 2 (Canal Disinfection) showed minimum PEP with a mean pain score (0.08) at the end of 48 hours which was statistically significant (P < 0.0001). However, Group 2 (Canal Disinfection) in comparison with Group 3 (Periapical Biostimulation) was found to be statistically not significant (P = 1.00).
Conclusion: Laser stimulation had a positive effect on PEP. Minimum PEP was seen in patients in which lasers were used for Canal Disinfection which was better than Periapical Biostimulation. However, it was found to be statistically not significant.

Keywords: Canal disinfection, laser, periapical biostimulation, postendodontic pain, single-visit root canal treatment

How to cite this article:
Aggarwal A, Dewan R. Comparative evaluation of different laser modalities on post endodontic pain in single visit root canal treatment: A randomized controlled trial. Endodontology 2020;32:142-7

How to cite this URL:
Aggarwal A, Dewan R. Comparative evaluation of different laser modalities on post endodontic pain in single visit root canal treatment: A randomized controlled trial. Endodontology [serial online] 2020 [cited 2022 Aug 14];32:142-7. Available from: https://www.endodontologyonweb.org/text.asp?2020/32/3/142/299281

  Introduction Top

Postendodontic pain (PEP) is defined as the pain of any degree that occurs after the initiation of root canal treatment (RCT). The development of PEP is usually due to acute inflammatory response in the periradicular tissues. It commences within few hours or days after the treatment. However, it is a poor indicator of pathosis and unreliable predictor of long-term success. It might undermine patients' confidence in their dentists or patient satisfaction with the treatment.[1] It is a paradox that though pain is the principle motivating factor for an individual to seek dental treatment, it is also an appreciable entity that dissuades the sufferer from cheerfully opting for a RCT.[2]

Pain is a very subjective experience personally influenced by many factors, including, but not limited to, behavioral and cultural learning and expectations, attention response from surrounding people, physical (genetic) factors, and psychological factors. Quantifying and standardizing pain objectively across a group of individuals can be challenging. Numeric and verbal self-rating scales or behavioral observation scales have traditionally been used in clinical studies.[3]

Low-level laser therapy (LLLT) was first described by Mester et al.[4] who found that LLLT biostimulates the growth of hair. The recently rapid developments in laser technology and better understanding of biointeractions of different laser systems have broadened new horizons for clinical use of laser in contemporary endodontics. A laser is a monochromatic, collimated, coherent, and intense beam of light produced by stimulated emission of radiation of a light source. This light source consists of a glass or ceramic tube containing an active medium (in gas, liquid, or solid form) which identifies and distinguishes the type of emitted laser beam. Visible beams (i.e., the Argon laser at 488 or 518 nm) and invisible beams in the infrared range (i.e. CO2, erbium-substitutedyttrium–aluminum–garnet, erbium, chromium-doped yttrium–scandium–gallium–garnet, and neodymium-doped yttrium–aluminum–garnet) are used in dentistry.[5]

The properties of a specific laser beam, particularly wavelength and the optical characteristics of the particular target tissue, determine the type and the extent of interaction which may occur. LLLT is well established in clinical dentistry because of its anti-inflammatory and regenerative effects. Recently, LLLT is considered as an adjunct to alleviate postdental procedure pains. Furthermore, LLLT has also shown nonthermal and biostimulatory effects, and the energy output of the device is low enough not to exceed an irradiated tissue temperature of 36.5°C. Activation of microcirculation, along with cellular metabolism, has been observed following LLLT.[5]

Although the mechanism of pain relief subsequent to LLLT still needs to be studied, pain mediation and stimulation of endorphin production were proposed. Moreover, some researchers attribute the analgesia to anti-inflammatory and neural effects of LLLT, including stimulation of nerve cell and lymphocyte respiration, stabilization of membrane potentials, and the release of neurotransmitters in the inflammatory tissue. In addition, elongation of substance P and calcitonin gene-related peptide-rich neuritis was found to be reduced in vitro.[5]

  Materials and Methods Top

The study protocol was approved by the Research and Ethics Committee Ref. No. ITSCDSR/L/2018/115. Ninety-nine male patients within the age group of 18–50 years were selected to take part in this clinical trial.

Nonvital maxillary and mandibular molars requiring RCT were selected for the study. A clinical examination was conducted that included thermal and electric pulp testing (heat and cold), percussion and palpation evaluation, periodontal probing, mobility assessment, and a periapical radiograph. All the past and present symptoms were noted. A diagnosis of pulpal necrosis was determined on the basis of the history, clinical, and radiographic features.

Inclusion criteria

  1. Male patients
  2. Age group of 18–50 years
  3. Asymptomatic teeth
  4. Nonvital maxillary and mandibular first and second molars
  5. Periapical radiolucency of not >2 mm
  6. Teeth with no history of RCT
  7. Teeth with no pus or inflammatory exudate draining out of the canal
  8. Teeth with no sinus tract
  9. Teeth with sound periodontal apparatus.

Exclusion criteria

  1. Female patients
  2. Patients who have consumed any type of analgesic at least 6 h prior to the treatment
  3. Patients with diabetes mellitus, hypertension, and other systemic diseases known to affect healing status
  4. Patients reporting for root canal retreatment
  5. Patients with known allergy to any of the drugs used in this study
  6. Teeth having internal or external resorption
  7. Teeth with open apices
  8. Moderate to advanced periodontal diseases.

A preoperative radiograph was taken to check the canals, periodontal tissues, and the presence of periapical radiolucency. Patients were informed about the nature of the study and informed consent was obtained before the treatment. The patients were then divided randomly into three groups based on the instrumentation technique: Group 1 (n = 12) Control (Placebo); Group 2 (n = 12) Laser Canal Disinfection; and Group 3 (n = 12) Laser Periapical Biostimulation. The laser used for all the interventions in the study was Biolase epic X. All teeth were treated in a single appointment by the same operator.

Before the administration of the anesthetic, a test dose of 1:10 dilution of 2% lignocaine was administered intradermally on the forearm to determine if the patient was allergic to a local anesthetic. Once it was determined that the patient was not allergic to the anesthetic, the root canal procedure was initiated. Each patient was anesthetized with a solution of 2% lidocaine HCl with 1:100000 epinephrine. The tooth was isolated with a rubber dam. An occlusal reduction was performed and coronal access was made using sterile round bur (#2). The working length was determined and the instrument was kept 0.5 mm short of radiographic apex. After the establishment of working length, an initial glide path was established using a hand file. The root canals were instrumented with ProTaper Universal Rotary (Dentsply Maillefer) according to the manufacturer's instructions.

Canals were irrigated using 30G side-vented needles with sterile saline and 2 ml of 2.5% NaOCl after each instrument was used. The final irrigation was performed using 1.5 ml of 17% ethylenediaminetetraacetic acid and 1.5 ml of normal Saline. A total of 5 ml solution was used for standardization. The canals were then dried using paper points. Obturation was done by the lateral compaction method using zinc oxide eugenol sealer and gutta percha cones of different taper according to the biomechanical preparation done in the group. In Group 1, for the Placebo effect, a mock laser therapy was carried out after obturation. In Group 2, for the Laser Canal Disinfection group, after instrumentation, the laser tip was placed 1 mm short of working length in the wet canal moving from the orifice to the apex and back directly. The laser was activated only while withdrawing. The tip was withdrawn in a circular motion at the rate 1 mm/s. This step was repeated six times per canal at intervals of 10 s between each activation. Laser specifications: semiconductor diode laser was used with a wavelength of 940 ± nm at 0.1 W in continuous mode.

In Group 3, for the Laser Periapical Biostimulation, the laser tip was positioned at the right angle to the mucosa at the level of apices. The laser tip was applied to both buccal and lingual/palatal mucosa at the right angle to the mucosa. It was activated for 2 intervals of 20 s each with a gap of 5 s in between each interval on each individual root apex a total exposure time of 80 s was allowed, at 10 mm from the end of the fiber to the tissue. Laser specifications: semiconductor diode laser was used with a wavelength of 940 ± nm at 70 J/cm 2 at 0.8 W at continuous mode for 2 intervals of 20 s each with a gap of 5 s in between each interval on each individual root apex a total exposure time of 80 s was allowed, at 10 mm from the end of the fiber to the tissue.

A temporary filling material was then placed and the patient was recalled after 48 h for postendodontic restoration.

A questionnaire was given to the patients at the end of the appointment and the patient was educated on how to assess and record the incidence and severity of pain at 6, 12, 24, and 48 h. Patients were asked to rate any pain occurring after the endodontic procedure using a visual analog scale (VAS). A rescue medication tablet ibuprofen 400 mg was prescribed to all the patients, and he was asked to record it if consumed. Patients were recalled after 48 hours with the filled questionnaire. Rating from the questionnaire was then tabulated. An illustration of how the trial was designed, analyzed, and interpreted is displayed in a flow diagram which presents the progress of all participants through the trial [Figure 1].
Figure 1: Consort flow diagram

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Statistical analysis

Data were entered into Microsoft Excel spreadsheet and were analyzed using Statistical Package for Social Sciences (SPSS) version 21 (IBM SPSS Statistics for Windows, version 21.0, IBM Corp., Armonk, NY). VAS scores for pain were summarized as mean and standard deviation [Table 1].
Table 1: Comparison of the mean pain scores between patients of the three groups

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Intergroup comparison of mean VAS scores was done using Kruskal–Wallis test along with post hoc pairwise comparison by Mann–Whitney U-test. An intragroup comparison was performed using the Friedman test and Wilcoxon test. The level of statistical significance was set at 0.05 [Table 2].
Table 2: Intragroup and intergroup comparison of visual analog scale pain scores among the three different groups with the mean, median, and standard deviation

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  Results Top

Intragroup comparison of VAS scores for pain showed that the highest mean postoperative pain scores were observed 6-h post treatment in all the groups with a significant decline thereafter (P < 0.05) [Table 2] and [Figure 2].
Figure 2: Graphical representation of the trends of pain with different laser modalities of all groups at different time intervals

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To obtain intergroup comparison, the results were subjected to post hoc pairwise comparison in which Group 2 (Canal Disinfection) showed a significantly lower mean VAS score when compared with Group 3 (Periapical Biostimulation), although it was not statistically significant, followed by Group 1 (Placebo) at all postoperative time points (P < 0.05). None of the 36 participants reported severe pain or flare-up during the period of the study.

  Discussion Top

Pain of endodontic origin is widely feared due to its intensity. Pak and White [6] showed that postobturation pain prevalence was 40% at 24 h and reduced to 11% at 1 week. The severity of pain was substantially decreased within the first 2 days.[1]

However, the etiology of PEP is multifactorial. Age, sex, tooth type or location, preoperative pain, periapical radiolucency, pulpal status, prophylactic drug, anesthetic agent, working length method, instrumentation, irrigation, use of lasers, obturation technique, occlusal reduction, postoperative drug, and operator contribute to PEP.[6]

In our study, only male patients were included to exclude any bias. Single-visit treatment was chosen to maintain a simple uniform protocol and to rule out the potential influence of intracanal medication.

VAS was used as a result of its ease, valid, and reliable scale to measure pain.[7] It provides a continuous scale for subjective magnitude estimation and consists of a straight line, the limits of which carry a verbal description of each extreme of the symptom to be evaluated. The line is usually 10 cm long and vertical. VAS is more sensitive to small changes than simple descriptive ordinal scales. However, one of the limitations of the VAS is that it must be administered on paper or electronically. Caution is required when photocopying the scale because this can lead to significant changes in its length. The failure of VAS is between 4% and 11%, but this can be reduced if the tool is carefully explained to the patient.[8]

The Epic X Biolase Laser was used for this study. It utilizes a solid-state diode as a semiconductor source for invisible infrared radiation. The energy is delivered to the treatment site via a flexible fiber connected at one end to the laser source and the other end to the handpiece. Various types of single-use, disposable tips are designed and optimized for different applications. The device is activated by means of a wireless footswitch.

The following observations were made at all given intervals of time (6, 12, 24, and 48 h):

Group 2 = Group 3 > Group 1

Canal Disinfection = Periapical Biostimulation > Placebo

There was a reduction in pain when the laser was used for Canal Disinfection when compared to both the Placebo and the Laser Biostimulation group.

This could be attributed to the thermal effects of high-density energy of the laser. With regard to other effects of laser irradiation of root canals, Levy [9] reported that the degree of cleanliness of root canals was greater due to the evaporation of debris and sealing of dentinal tubules after using laser than that seen in conventional methods.

Dederich et al.[10] reported that laser irradiation sealed dentinal tubules and smoothed root canal walls.

It may be suggested that subsequent to removal of debris and smear layer using chemomechanical preparation, diode laser compounded with a fiber optic tip could provide greater accessibility to formerly unreachable parts of the tubular network resulting in the superior bactericidal effect in the root canal dentin.

The superior bactericidal effect of diode laser irradiation could be attributed to its greater depth of penetration (up to 1000 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 a progressive decrease in the diameter of the deep dentinal tubules, the penetration of irrigants is restricted. However, 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.[11]

LLLT may reduce pain related to inflammation by lowering, in a dose-dependent manner, levels of prostaglandin E2, prostaglandin–endoperoxide synthase 2, interleukin 1-beta, tumor necrosis factor-alpha, the cellular influx of neutrophil granulocytes, oxidative stress, edema, and bleeding. The appropriate dose appears to be between 0.3 and 19 J/cm 2.[12]

Other theory proposed is the neural inhibition as a mechanism of pain relief, which is widely accepted. In a study done, it was found that conduction velocity was considerably reduced. It acts on the biostimulation because of the increase in the production of mitochondrial adenosine triphosphate, increasing the threshold of the free nerve endings, providing an analgesic effect due to an increase of β-endorphine in the cephalorrhachidian liquid. The reduction of pain occurs because of the inhibition of the cyclooxygenase enzyme, which suspends the conversion of the arachidonic acid into prostaglandin.[12]

Low level laser inhibit the release of mediators from injured tissues, decrease concentration of chemical agents such as histamine, acetylcholine, serotonin, H + and K+, all of which are pain mediators. They inhibit concentration of acetylcholine, a pain mediator, through increased acetylcholine esterase activity, cause vasodilatation and increase blood flow to tissues, accelerating excretion of secreted factors. This causes better circulation which leads to a decrease in tissue swelling, decrease tissue edema by increasing lymph drainage, remove the pressure on nerve endings, resulting in stimulation decrease, decrease sensitivity of pain receptors as well as transmission of impulses. A decrease in cell membrane permeability for Na+ and K+ is observed which cause neuronal hyperpolarization, resulting in increased pain threshold, the production of β-endorphin, injured tissue metabolism is increased by electromagnetic energy of laser. This is induced by ATP production and cell membrane repolarization.[13]

Bjordal et al.[14] reported that LLLT can modulate inflammatory processes and reduce acute inflammatory pain by lowering, in a dose-dependent manner, levels of prostaglandin E2, interleukin 1 beta, tumor necrosis factor-alpha, oxidative stress, and edema. LLLT can also decrease the firing frequency of nociceptors. LLLT selectively inhibits nociceptive signals in the peripheral nerves.

The null hypothesis was thus rejected that there is no effect of Laser Disinfection or Periapical Biostimulation on PEP.

  Conclusion Top

Within the limitations of the present study, laser stimulation had a positive effect on PEP. Minimum PEP was seen in patients in which laser was used for Canal Disinfection than Periapical Biostimulation. However, it was found to be statistically not significant. Further clinical studies should be carried out to analyze the potential Laser Stimulation and other regimens examining different clinical conditions such as single- versus multiple-visit endodontic treatment.

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Conflicts of interest

There are no conflicts of interest.

  References Top

El Mubarak AH, Abu-Bakr NH, Ibrahim YE. Postoperative pain in multiple-visit and single-visit root canal treatment. J Endod 2010;36:36-9.  Back to cited text no. 1
Bhagwat S, Mehta D. Incidence of post-operative pain following single visit endodontics in vital and non-vital teeth: An in vivo study. Contemp Clin Dent 2013;4:295-302.  Back to cited text no. 2
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Attar S, Bowles WR, Baisden MK, Hodges JS, McClanahan SB. Evaluation of pretreatment analgesia and endodontic treatment for postoperative endodontic pain. J Endod 2008;34:652-5.  Back to cited text no. 3
Mester E, Szende B, Gärtner P. The effect of laser beams on the growth of hair in mice. Radiobiol Radiother (Berl) 1968;9:621-6.  Back to cited text no. 4
Asnaashari M, Ashraf H, Daghayeghi AH, Mojahedi SM, Azari-Marhabi S. Management of post endodontic retreatment pain with low level laser therapy. J Lasers Med Sci 2017;8:128-31.  Back to cited text no. 5
Nagendrababu V, Gutmann JL. Factors associated with postobturation pain following single-visit nonsurgical root canal treatment: A systematic review. Quintessence Int 2017;48:193-208.  Back to cited text no. 6
Krithikadatta J, Sekar V, Sudharsan P, Velumurugan N. Influence of three Ni-Ti cleaning and shaping files on postinstrumentation endodontic pain: A triple-blinded, randomized, controlled trial. J Conserv Dent 2016;19:311-6.  Back to cited text no. 7
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Levy G. Cleaning and shaping the root canal with a Nd:YAG laser beam: a comparative study. J Endodon 1992;18:123-7.  Back to cited text no. 9
Dederich DN, Zakariasen KL, Tulip J. Scanning electron microscopic analysis of canal wall dentin following neodymium-yttrium-aluminium-gamet laser irradiation. J Endod 1984;10:428-31.  Back to cited text no. 10
Pawar SS, Pujar MA, Makandar SD, Khaiser MI. Postendodontic treatment pain management with low-level laser therapy. J Dent Lasers 2014;8:60-3.  Back to cited text no. 11
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Nabi S, Amin K, Masoodi A, Farooq R, Purra AR, Ahangar FA. Effect of preoperative ibuprofen in controlling postendodontic pain with and without low-level laser therapy in single visit endodontics: A randomized clinical study. Indian J Dent Res 2018;29:46-50.  Back to cited text no. 12
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Doǧanay Yıldız E, Arslan H. Effect of low-level laser therapy on postoperative pain in molars with symptomatic apical periodontitis: A randomized placebo-controlled clinical trial. J Endod 2018;44:1610-5.  Back to cited text no. 13
Bjordal JM, Johnson MI, Iversen V, et al. Low-level laser therapy in acute pain: a systematic review of possible mechanisms of action and clinical effects in randomized placebo-controlled trials. Photomed Laser Surg 2006;24:158-68.  Back to cited text no. 14


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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