Assessment of Healing and Pain Response at Mandibular Third Molar Extraction Sites with and Without Pre- and PostOperative Photobiomodulation at Red and Near-Infrared Wavelengths: A Clinical Study.

Background: Photobiomodulation (PBM), formerly known as low-level laser therapy, has been successfully used for its anti-inflammatory and analgesic properties in postoperative care. It is also known to have a positive effect on healing and regeneration, at an appropriate power and wavelength. Aim: The main objective was to assess the effect of preoperative as well a postoperative irradiation with low power of 100 milliwatts (mW) and 810-nanometer (nm) (near-infrared) and 660-nanometer(nm) (red) wavelengths on healing as well pain at mandibular third molar extraction sockets. Methodology: Twenty-six patients who were scheduled for mandibular third molar extractions were enrolled in the study and were randomly assigned to the experimental and control group. The experimental group consisted of 13 patients who were subjected to 810-nm irradiation at 100 MW at the site immediately before and after the extraction was completed. In addition, they also received a transcutaneous irradiation of 660-nm wavelength light 1-day postoperatively. The control group received no irradiation immediately after postextraction or the day after. Pain and healing were assessed using the visual analog scale and Turnbull and Howley's Index for soft-tissue healing on the 7th and the 21st days. Data were analyzed using the Mann-Whitney test.
Results: The results showed clinically significant improvements in healing index scores and pain scores of the experimental group than the control group (P < 0.0001).
Conclusion: PBM at an appropriate wavelength is a potential tool for the management of pain and accelerating healing at mandibular third molar extraction sites. Copyright:

INTRODUCTION

Third molars ideally erupt/emerge in the oral cavity somewhere between 17 and 21 years of age. There are several indications for a third molar to be extracted or disimpacted whether it is pain or impaction, caries, or root resorption in second molars.[12] Procedure of third molar extraction is very susceptible to developing complications, pain being an extremely common among them.[34] Corticosteroids are routinely administered in conjunction with local anesthesia and nonsteroidal anti-inflammatory drugs (NSAIDs) to keep postoperative pain in check.[5] Patients tend to harbor some fears and anxieties regarding third molar extraction because of their own or others' experiences of postoperative pain.[6] Therefore, making the postoperative experience of third molar extraction procedures entails detailed perioperative instructions, analgesics, and home maintenance care, etc.

The discovery of low-level laser therapy's (LLLT) is credited to Professor Andre Mester, a Hungarian physician. Mester set out to discern whether ruby lasers could cure malignant tumors in rats, but one needs to note that Mester's custom ruby laser had low power and short wavelength. Postirradiation, profuse hair growth, and enhanced wound healing in the incision lines were noticed, in the areas where the tumors had been surgically implanted. This observation led to the understanding that low power and short wavelengths had tremendous beneficial biological effects.[78]

At the center of this phenomenon is cytochrome c oxidase the chromophore, which absorbs or has an affinity for certain wavelengths of light or photons.[9] Under the influence of this short wavelength and low power (1 mw-5W), there is upregulation of mitochondrial adenosine triphosphate and downregulation of reactive oxygen species in oxidatively stressed cells, leads to anti-inflammatory, analgesic, and regenerative effects.[10] LLLT has been rechristened as photobiomodulation (PBM) now.[11] The suggested definition of PBM by WALT/NAALT is “A light therapy that utilizes nonionizing light sources, including LASERS, LEDs, and broadband light, in the visible and infrared spectrum.[12]

The premise of PBM is to use low power in the range of 25 milliwatts-200 milliwatts, wavelengths at red (620–740 nm) and at near-infrared (NIR, 770–1200 nm) light for small intervals to activate chromophores.

This study is an attempt to use the unique property of these wavelengths and maximize the number of irradiations, to bring about better healing and pain control in third molar extraction sites with pre- and postoperative irradiations.

METHODOLOGY

Twenty-six patients were selected from the oral and maxillofacial department as and when patients were scheduled for extraction of wisdom teeth for various complaints such as impactions and gross destructed teeth. These patients were enrolled in the study and were divided into experimental group comprising 8 male and 5 female participants (13) and control group comprised 6 female and 7 male participants (13). An informed written consent was obtained from the patients. Ethical clearance was also procured for the study from the institutional ethical clearance committee (Ref. No.: SDC/SMG/2019/213.

Experimental group received PBM a total of three times, (1) before procedure, 12J (joules), (2) immediately after, 6J, and (3) 1-day postoperatively, 6J. Wavelength was 810 nm at power of 100-milliwatts for 120 s prior and 60 s for both postextraction irradiations. The 3rd irradiation was given transcutaneous/extraoral so as to not disturb the wound. The LED tip was delicately kept in contact with the tissues throughout all irradiations. The LASER unit used was INDILASE, Medsol, Medical Equipment Manufacturers. Hosur, Bangalore. Control group did not receive any irradiation; both groups received standard postoperative instructions along with analgesics and told to keep the wound area clean with chlorhexidine 0.2% rinse. Healing index scores[13] and VAS pain scale[14] scores were recorded for both experimental and control group on the 7th and the 21st day. VAS scale was not recorded on the 2nd day postoperatively to avoid the scale being influenced by patients' intake of pain medication.

RESULTS

Healing index scores and VAS pain scale scores were recorded for both groups on the 7th and the 21st day. Pain scale scores before extraction were not recorded as the PBM therapy was not directed as therapy toward any etiology or pathology. The statistical analysis was performed using the SPSS software v25.0 (developed by IBM, California, USA). Since it was a small sample size of 26, instead of calculating the mean, the Healing Index scores and VAS scale scores were divided into quartiles.

On the 7th day, healing index median for experimental group (median:3) was higher than control group (median: 2) by 1 point. The corresponding quartiles were 3 and 3.5 for experimental group and 2 and 2 for control group. Moreover, the difference between the median and quartiles between the two groups was statistically significant (P < 0.0001) [Table 1].

Table 1

Comparison between the patients healing index scores of experimental group and control group on the 7th and 21st day

Group	n*	Mean	SD	Minimum	Maximum	Percentiles			Mann–Whitney test
						25th	50th (median)	75th
Wound healing 7td day
Experimental group	13	3.23	0.44	3.0	4.0	3.0	3.0	3.5	Z: −4.1, †P: <0.0001, significant
Control group	13	2.08	0.49	1.0	3.0	2.0	2.0	2.0
Wound healing 21st day
Experimental group	13	4.15	0.55	3.0	5.0	4.0	4.0	4.5	Z: −4.3, †P: <0.0001, significant
Control group	13	2.69	0.48	2.0	3.0	2.0	3.0	3.0

*Number of patients, †Statistical significance at P<0.05. SD: Standard deviation

21st day healing index median for experimental group (median: 4) was again higher than control group (median: 3) by 1 point despite both groups having a better score than on the 7th day. Moreover, this difference was statistically significant. The difference between the quartiles also remained statistically significant [Table 1].

VAS score median [Table 2] on 7th day for experimental group (median: 1) was higher than control group (median: 7), and this difference was statistically significant (P < 0.0001). On the 21st day, the difference between the medians was down to 5 (experimental group median: 0, control group median: 5), and yet the difference remained statistically significant.(P < 0.0001) The difference between the quartiles on the 21st day also remained statistically significant.

Table 2

Comparison of visual analog scale scores between experimental group and control group on the 7th and 21st day

Group	n*	Mean	SD	Minimum	Maximum	Percentiles			Mann–Whitney test
						25th	50th (median)	75th
VAS 7td day
Experimental group	13	0.77	0.83	0.0	2.0	0.0	1.0	1.5	Z: −4.4, †P: <0.0001, significant
Control group	13	7.15	1.28	6.0	10.0	6.0	7.0	8.0
VAS 21st day
Experimental group	13	0.38	0.51	0.0	1.0	0.0	0.0	1.0	Z: −4.4, †P: <0.0001, significant
Control group	13	6.00	1.29	4.0	8.0	5.0	6.0	7.0

*Number of patients, †Statistical significance at P<0.05. SD: Standard deviation, VAS: Visual analog scale

DISCUSSION

A total of 26 patients who were scheduled for third molar extraction/disimpaction participated in this study. Experimental group showed better responses on the VAS pain scale index as well. Experimental group patients had no complaints of either discomfort or uneasiness.

There is previous evidence to show that both intraoral and extraoral irradiation (mostly to the masseter muscle) have been successfully carried out to reduce pain and trismus quite efficiently.[151617181920] Gasperini et al.'s study had no difference in pain between two groups; swelling resolution was significantly better in the PBM group.[19]

Patients in the experimental group of our study received two postoperative irradiations in addition to one preoperatively. Immediate postoperative irradiation was with 810 nm and 24 h later transcutaneously with 660 nm. Studies in the past with fairly similar protocols of postextraction irradiation of two or more PBM sessions in the red or near-infrared range have also achieved good analgesia. Singh et al. subjected the split-mouth extraction sites to 830 nm PBM immediate postoperatively, and at day 2, 4, and 7. Reduction in pain and swelling was significant.[21]

Koparal et al.' compared one dose PBM with two doses, with the second dose being 24-h postoperatively. The two-dose group exhibited better analgesia 7th day onward. This result is similar to our study where VAS scores had improved in the experimental group on the 7th day.[22] Multiple dosing has been used in premolar extraction pain control as well, at immediate postoperative, at 48 and 72 h with good results as compared to no PBM.[23]

Tuk et al. subjected the experimental group to a preinjection irradiation at the site with 810 nm at 200 mw. The test groups exhibited lower mean heart rates than the control group. Perhaps, a preinjection PBM is a good adjunct in managing patient's anxiety regarding third molar extraction.[24] In our study, in addition to preinjection PBM with 810 nm at 100 mw, extraction sites were also irradiated with 810 nm (100 mw) immediate postoperatively and with 660 nm (100 mw) transcutaneously 24 h later. In a similar study, extraction sites were irradiated preoperatively as well as postoperatively and control sites subjected to LA, pain response was similar with both groups but NSAIDs intake was far less with the preoperatively irradiated group. A preoperative irradiation and multiple postoperative irradiations are ideal for superior pain control.

We used Landry et al.' index to assess healing in both groups at 7 and 21 days. Experimental group fared better than control group with the tissue response when assessed on both intervals, and the difference between the responses was statistically significant. The index includes assessment for redness, bleeding, epithelialization, suppuration, and granulation tissue.[13] Thermography has been used to assess healing in a study that resulted resulted in inconclusive findings, despite 4 PBM applications postoperatively on 3 consecutive days.[25] However 14th day onward, difference in healing between irradiated sites and nonirradiated sites turned out to be highly significant.

Despite decades of research that has gone into pain and tissue management at third molar extraction sites using LLLT or PBM, there is no consensus regarding energy dosage, yet the results seem to be always better with PBM than without.

PBM in addition also activates microcirculation, brings about better tissue metabolism, analgesic effects, and vasodilatation.[26] When PBM is applied preoperatively or preinjection, it is these properties that tend to enhance pain control and contribute to the managing swelling and trismus.

Limitations

A larger sample size with the inclusion of maxillary molars would have gathered more evidence in favor of PBM for pain control in third molars. Number of PBM dosages also could have been increased.

Future

Pain and healing are natural consequences of any invasive surgery. PBM with low-level laser light truly equips the clinician to alleviate a patient's fear regarding most oral procedures when used judiciously.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.