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Year : 2021  |  Volume : 32  |  Issue : 3  |  Page : 299-304
Evaluation of effect of low level laser therapy with intracanal medicament on periapical healing: A randomised control trial

Department of Conservative Dentistry and Endodontics, Coorg Institute of Dental Sciences, Virajpet, Karnataka, India

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Date of Submission14-Sep-2020
Date of Decision22-May-2021
Date of Acceptance08-Oct-2021
Date of Web Publication23-Feb-2022


Objective(s): Photobiomodulation, also commonly referred to as low level laser therapy (LLLT), uses light energy to elicit biological responses from the cell and normalise cell function. Using LLLT on bone has been demonstrated to be effective in modulating inflammation, accelerating bone cell proliferation and enhancing the healing process. The objectives of this study were to evaluate postoperative pain and periapical healing in two different groups. Materials and Methods: 40 subjects with periapical lesion were selected and were assigned randomly into two groups. Group I: Conventional root canal therapy along with LLLT. Group II: Conventional root canal therapy only. Radiographs were obtained and assessed at baseline, 3, 6 and 9 months postoperatively. The VAS pain scale was assessed post operatively at 0, 7th and 14th day respectively. The Independent t-test was used for evaluation of the data. Results: Significant differences were noted in reduction of periapicallesion at 3 and 9 months follow-up. The healing was better in Group I that received LLLT with the conventional Root Canal Treatment (RCT). Values for postoperative pain was lower in Group I than Group II, but were statistically non-significant. Conclusion(s): LLLT when used as an adjunct with conventional root canal treatment showed acceleration of the healing process of periapical lesions. LLLT has a positive effect on modulating the immune response for favourable healing.

Keywords: Apical periodontitis, low level laser therapy, periapical healing, photobiomodulation

How to cite this article:
Shah D, Ponappa MC, Ponnappa KC. Evaluation of effect of low level laser therapy with intracanal medicament on periapical healing: A randomised control trial. Indian J Dent Res 2021;32:299-304

How to cite this URL:
Shah D, Ponappa MC, Ponnappa KC. Evaluation of effect of low level laser therapy with intracanal medicament on periapical healing: A randomised control trial. Indian J Dent Res [serial online] 2021 [cited 2022 Oct 7];32:299-304. Available from:

   Introduction Top

Apical periodontitis is considered to be a sequel to infection of microbial origin of the pulp space, followed by an inflammatory process around the apex.[1] Hence, the management of the microbial load needs to be considered with the aid of endodontic treatment.

Ideally, to achieve disinfection of canals, mechanical preparation of the canal along with appropriate irrigating solutions and intracanal dressing in between the appointments is necessary.[1]

In the past, surgical intervention was considered to be the only option for the treatment of large periapical lesions. However, better understanding of the genesis, pathologic nature and clinical behaviour of endodontic periapical lesions and their successful treatment in various clinical trials have started favouring a nonsurgical approach. Use of newer irrigants, irrigation activation devices, improved mechanical preparation devices and use of laser in disinfection of canals have improved the healing in case of large periapical lesion using non-surgical approach.[2]

Low-level laser therapy (LLLT), also known as photobiomodulation (PBM), brings about normalisation of cell function and induces biological responses from the cells. One of the advances is the concept of photobiomodulation of the apex. The described main effects are anti-inflammatory, immune-stimulating, antibacterial, analgesic and induction of cell proliferation, which will enhance healing in the peri-apex. Visible red light at 633 nm has additional beneficiary outcome due to the stimulatory effects on fibroblasts inducing collagen turnover, with increased ATP production and has positive modulation of the inflammatory cells like macrophages, neutrophil, etc., which reduces the time taken for periapical healing.[3] The aim of the study was to evaluate the role of LLLT in periapical healing. A study by Lucas Freitas de Freitas showed that phototherapy is an important strategy used to stimulate and/or increase bone formation post injury. Laser with low power output can stimulate osteoblast and inflammatory mediators positively to enhance the healing process.[4]

   Material and Methods Top

The present parallel group, double-blind, randomised controlled trial was carried out in the Department of Conservative Dentistry and Endodontics, Coorg Institute of Dental Science, Virajpet. 40 subjects were included in the study after the fulfilment of the inclusion criteria and were randomised to compare the radiographic and clinical outcomes of healing of the periapical region after root canal therapy with and without low level laser therapy (LLLT). The trial was approved by the Institutional Review Board and was registered prospectively with Clinical Trial Registry of India (CTRI Registration No: CTRI/2018/02/011775 [Registered on: 08/02/2018]. Ethical approval was taken and got approved on 30-11-2017.

Study population

Inclusion criteria

  1. Teeth with mature root.
  2. Permanent single-rooted teeth with nonvital pulps and apical periodontitis after clinical and radiographic confirmation.
  3. Presence of periapical lesion >2 mm and <8 mm.

Exclusion criteria

  1. Permanent multirooted teeth.
  2. Patients with underlying systemic conditions and special healthcare needs.
  3. Malformed teeth and teeth with developmental root defects.
  4. Teeth that were previously endodontically treated.

Sample size estimation

The sample size was calculated based on a study conducted by Sultan Zeb Khan titled: Morphological effect of diode laser irradiation of periapical lesion in rat. This study was taken as a base for the present study.

Where, S.D is standard deviation, Zα =1.96 at 95% confidence interval

Zβ =75% Power = 0.675

UT-Us = expected mean difference = 0.2025

= 17.19/group

To increase the accuracy of the study and to reduce experimental error, the sample size was increased to 20 per group. Thus, the final total sample size was 40.

Desired primary outcome

Improvement in pain control in apical lesion cases with increased osseous healing at the peri-apex.

Secondary outcome

Enhanced healing of the periapical tissue. A detailed history related to pain was recorded. Full mouth hard and soft tissue examinations were carried out, along with standardised periapical radiographs for any teeth with possible indication of apical periodontitis, before the start of the clinical study. Parallel cone technique with standard exposure was used to obtain accurate digital radiographs. Informed, written consent for the treatment of the patient was obtained prior to clinical procedures after explanation of the procedure protocols and risks associated with it. Patients were free to opt out of the study at any given point of time. CONSORT guidelines were followed in the randomised controlled trial [Figure 1]. Patients were assigned randomly into two groups by block randomisation; allocation concealment was done with the closed envelope method. Randomisation, enrolment and assignment of participants to interventions were done by two endodontists, who were not involved in the study. Participants and the investigators, who assessed the outcomes of the interventions, were blinded to the procedure. All treatment sessions were carried out by a single operator to eliminate inter-operator bias.
Figure 1: Consort flow chart

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The following root canal protocol was used for both the groups:

Case group (I): Root canal therapy was initiated and a mixture of aqueous 2% Chlorhexidine and Calcium hydroxide powder as an intracanal medicament was placed in between appointments. Three sessions of LLLT as an adjunct was given at 0, 7th and 14th day. Root canal therapy was completed on 14th day.

Control group (II): Root canal therapy was initiated and a mixture of aqueous 2% Chlorhexidine and Calcium hydroxide powder as an intracanal medicament was placed in between appointments. Root canal therapy was completed on 14th day. In the control group, the laser unit was used, with the safety cap on, thereby without actually irradiating the tissues, and just having the same sound of the device.

After confirming the diagnosis, anaesthesia was achieved by administering 2% lidocaine with1:80,000 epinephrine (Xicaine®, ICPA Health Products, India). The tooth was isolated using a rubber dam (Hygenic®, Coltene, USA).

Access cavity preparation was followed by working length determination using a PROPEX II Apex Locator (DENTSPLY Maillefer, Switzerland) and confirmed using a digital radiographic method. Cleaning and shaping were done by step back method using hand files till size No. 45 at the apex (K-file DENTSPLY Maillefer, Switzerland). 5% NaOCl (10 ml) (Vensons India, India) was used as the main irrigant followed by 17% EDTA (Vishal Dentocare Pvt Ltd). Saline was used as an intermediate irrigating solution before the use of 2% CHX (STEDMAN Pharmaceutical Pvt Ltd, India). A mixture of 2% Chlorhexidine and calcium hydroxide (DentPro, India) was placed using lentullospiral size 20 file, (DENTSPLY Maillefer, Switzerland) as an intracanal medicament in between appointment and temporary restoration was placed (Cavit- G, 3M ESPE, Germany). RCT was completed using standard protocols followed by permanent restoration using nanohybrid composite (3M ESPE, Germany). LLLT was applied at the peri-apex for duration of 1 minute for each session with 660 nm Duolase laser (INDILASE, India), at a power setting of 100 mW in continuous mode. Total of three sessions of laser was applied to the case group, whereas control group did not receive actual laser irradiation.

Assessment of pain

A modified visual analogue scale (VAS) was used for assessment and statistical comparison of pain scores. Patients were explained about the scale, its value and were asked to assess the pain experienced by them at 0, 7th, and 14th day respectively.

Assessment of radiograph

Digital radiographs were obtained before the start of the treatment, at the end of the treatment and postoperatively at intervals of 3, 6 and 9 months. To avoid changes in angulation and produce repeatable radiographs at each visit, these were taken using a paralleling technique with RINN XCP film holder. Radiographs were measured in their maximum dimension using the RVG software in subsequent follow-ups (3, 6 and 9 month) and were compared to preoperative radiographs for the percentage reduction in the size of periapical lesions. These radiographs obtained at different intervals were compared to the standard template radiographs of periapical index and scoring were done accordingly.

Endodontist was blinded about the study and its groups. All the measurements and scoring were checked again with them to reduce bias. In case of differences between the observers in the scoring and measurement, third observer was considered [Figure 2] and [Figure 3].
Figure 2: Group 1 Case: radiograph showing baseline till 9 month follow-up

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Figure 3: Group 2 Control: radiograph showing baseline till 9 month follow-up

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The analysis of digital images was carried out by means of a computer program: ImageJ (U.S. National Institutes of Health, Bet Bethesda, Maryland, USA,, 1997—2011). Statistical Analysis was performed using inferential statistics, independent t-test, Chi-square tests, SPSS for windows.

The periods of recruitment: 1-4-2018 to 1-2-2019.

Follow-up: 1-1-2019 to 1-12-2019 [Figure 2] and [Figure 3].

   Results Top

  1. Pain intensity was analysed using Independent t -test for comparison between the two independent groups. Mean expression of pain intensity immediate postoperatively, at 7th and 14th day post operatively were noted to be less in the case group than the control group. Thus, patients experienced less pain in the laser-treated group than control group. But the statistical value was non-significant [Table 1] and [Figure 4].
  2. Percentage reduction in the size of the periapical lesion was analysed by Independent t-test for comparison between the two independent groups. The mean reduction score was less in the control group than the laser-treated group. It was observed radiographically that the healing of the periapical region was more in the laser-treated group than the control group for 3rd and 9th month with statically significant values [Table 2] and [Figure 4].
Table 1: Statistical analysis of visual analogue scale

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Table 2: Statistical analysis of periapical index

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Figure 4: (a) Comparison of Mean VAS Scores between Group I and Group II at various intervals. (b) Comparison of Mean periapical index between Groups I and II at various intervals

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In the follow-up of 9 months following the clinical intervention, both the primary and secondary objectives of the study were achieved.

Evaluation of digital radiographs showed improved osseous and periapical tissue healing; clinically, reduction in the pain intensity was noted in the laser-treated group when compared to the control group.

   Discussion Top

The purpose of this parallel group, double-blind, randomised controlled trial was to compare the outcome of root canal treatment of teeth with apical periodontitis, assisted with and without LLLT. The prevalence of periapical radiolucency varied from 0.5%–13.9%.[5] Many of these lesions often go unnoticed, until they present with symptoms like pain, pus discharge and/or discolouration of the teeth.[6] Hence, this study was designed to evaluate the healing in apical periodontitis cases.

Symptomatic apical periodontitis presents clinically as a painful response to biting or tenderness on percussion and expansion of cortical bone due to the inflammation of periapical tissues. However, the presence of radio-graphic changes in asymptomatic apical periodontitis can be diagnosed with intraoral radiographs, CBCT, OPG and Ultrasound.[7] In the mandible, the buccal alveolar process is very thin in the anterior segment. Due to the thickness of bone and interference of other anatomical structures in the posterior region, it becomes difficult to assess radiographic changes due to superimposition.[4] Thus, in this study, single-rooted teeth in anterior region were selected.

PBM refers to the use of light in the red spectrum of wavelength which ranges from 600–700 nm and near-infrared spectrum ranges from 780–1100 nm. Its application brings about tissue repair, decreased inflammation and produces analgesia.[3] The low power light source (laser or LED, usually below 500 mW) when used, does not lead to any temperature rise of the target tissue and also no gross changes occur in the tissue structure.[5]

A review by Márcia Martins Marques on LLLT stated that the ddMSCs follow the Arndt-Schulz law. No effects were observed in the cells, when energy applied was more or less than a therapeutic window (1–4 J/cm2). The secondary effects observed of PBM in-vitro, were mostly cell viability, proliferation and odonto-osteogenic differentiation which could be related to tissue regeneration. An accelerated deposition and mineralisation of the extracellular matrix was observed secondary to an increased alkaline phosphatase (ALP) activity immediately after laser irradiation.[8]

In the present in-vivo study, enhanced healing of periapical tissues was observed, which may be attributed to the PBM therapy.

Another review article by Endre Mester showed positive correlation of low energy density and cell growth with an increase in osteocalcin and alkaline phosphatase levels.[7]

A study performed by Stein et al. demonstrated dose-related ALP-specific activity using a 670 nm non-thermal diode, output of 400 mW and energy density of 1 or 2 J/cm2 in continuous mode, where lower levels of ALP-specific activity noted at dose of 2 J/cm2.[8]

In the present study, the parameters used were in accordance with previous studies. The parameters set were 660 nm non-thermal diode laser unit, with an output of 100 mW and energy density of 1 J/cm2 in continuous mode for 80 s for irradiating the periapical region of the involved tooth. It was noted that there was a significant decrease in the mean value score for the laser group than the other group. Statistically significant values for the decrease in lesion size at time intervals of 3 months (P value of 0.014) and 9 months (P value of 0.026) were noted. The possible mechanisms for faster reduction in size of lesion could have been the initiation of the pro-inflammatory cells and osteoblast by LLLT, which was in accordance with the study by Amid et al.[9] In the present study, it would have initiated the pre-osteoblast to produce normal osteoblast with no difference in bone structure. These results were in accordance with the study conducted by Renata A. Nicolau using 660 nm.[9]

Previously, many studies were done on stem cell lines and animal study to know the effect of LLLT. Thus, the previous studies served as the basis for the present randomised control trial, where the effect of LLLT was evaluated in addition to the conventional root canal therapy. However, the present study has few limitations related to small sample size and irregular follow-up with patients.

In spite of these limitations, since much data for in vivo studies on the effect of LLLT on periapical lesion are not available, this study can be the basis for further clinical research with a larger sample size, where supplementary beneficial effects of laser in periapical healing could be assessed.

   Conclusion Top

The application of LLLT during the treatment resulted in the lower pain intensity experienced by the patient. Also, it was observed that the lesion size reduction was maximum in the laser group than the non-laser group.

This raises the scope of decreasing the time frame needed to heal, even in lesions with extensive periapical involvement. Also, this treatment modality being non-invasive provides the benefits with minimum side effects.

This unique study will serve as a basis for future studies, where further beneficial effects of laser in periapical healing could be evaluated.


I would like to thank Dr Chandrashekhar Yavagal for helping me in designing the study and Dr. Maitreyee Bhosle for her contribution in compilation of the data.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Figdor D. Apical periodontitis: A very prevalent problem. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:651-2.  Back to cited text no. 1
Kunhappan S, Kunhappan N, Saraf KK, Kridutt V. Nonsurgical endodontic treatment of teeth associated with large periapical lesion using triple antibiotic paste and mineral trioxide aggregate apical plug: A case series. J Conserv Dent 2017;20:141-5.  Back to cited text no. 2
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Calderhead RG. Review article: The photobiological basics behind Light-emitting diode (LED) phototherapy. Laser Ther 2007;16:97-108.  Back to cited text no. 3
De Freitas LF, Hamblin MR. Proposed mechanisms of photo-bio-modulation or low-level light therapy. IEEE J Sel Top Quantum Electron 2016;22:7000417.  Back to cited text no. 4
Archana D, Gopikrishna V, Gutmann JL, Savadamoorthi KS, Pradeep Kumar AR, Narayanan LL. Prevalence of periradicular radiolucencies and its association with the quality of root canal procedures and coronal restorations in an adult urban Indian population. J Conserv Dent 2015;18:34-8.  Back to cited text no. 5
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Huumonen S, Orstavik D. Radiological aspects of apical periodontitis. Endod Top 2002;1:3-25.  Back to cited text no. 6
Marques MM, De Cara SP, Abe GL, Pedroni AC, Diniz IM, Moreira MS. Effects of photo-bio-modulation therapy in dentoalveolar-derived mesenchymal stem cells: A review of literature. Lasers Dent Sci 2017;1:1-7.  Back to cited text no. 7
Amid R, Kadkhodazadeh M, Ahsaie MG, Hakakzadeh A. Effect of low level laser therapy on proliferation and differentiation of the cells contributing in bone regeneration. J Lasers Med Sci 2014;5:163-70.  Back to cited text no. 8
Nicola RA, Jorgetti V, Rigau J, Pacheco MT, dos Reis LM, Zangaro RA. Effect of low-power GaAlAs laser (660 nm) on bone structure and cell activity: An experimental animal study. J Lasers Med Sci 2003;18:89-94.  Back to cited text no. 9

Correspondence Address:
Dr. Deep Shah
Coorg Institute of Dental Sciences, Virajpet - 571 218, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_896_20

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2]

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