removal of third molars is a common procedure in oral surgery and it is associated with 
 postoperative complications such as pain , swelling and trismus . therefore , several 
 medications such as corticosteroids and non - steroidal anti - inflammatory drugs are often 
 recommended despite their common side effects such as bleeding , gastrointestinal irritation 
 and allergic reactions , which can evoke discomfort and health risks in patients1 . in terms of strategies used to minimize tissue damage in oral surgeries , the low - level 
 laser therapy ( lllt ) seems to offer many benefits in the stimulation of the healing process 
 and control of the inflammatory process by reducing the swelling and pain , with no reports 
 of adverse effects2 . according to medeiros et al.3 , the 
 effects of lllt are more evident in the early stages of wound healing . the use of polarized 
 light helps in resolution of inflammation and in increasing the collagen deposition as well 
 as the number of myofibroblasts however , previous studies have reported that in teenagers , lllt reduces 
 pain intensity without modifying the healing process4 . on the other hand , lllt showed better results in controlling 
 swelling and trismus when compared to ozone therapy5 . however , lopez - ramirez et al.2 found that lllt showed no positive effects in reducing pain , 
 swelling and trismus after the removal of third molars . these differences in the effects of lllt may be explained by the variability in the 
 protocols and surgical procedures performed1 , 2 , 6 . the lllt protocol should be determined considering the type of light used as well as the 
 tissue layers that need to be irradiated . in this context , the red spectra in the visible to 
 near - infrared spectra ( 620830  nm ) have the potential to stimulate photoreceptors in the 
 plasma membranes of cells . the higher wavelengths are absorbed by the deeper tissues and are 
 less active in the surface tissues7 . therefore , this study aimed to evaluate the efficacy of intraoral application of lllt 
 ( 660  nm ) in controlling pain intensity , swelling and interincisal opening in oral 
 surgery . this study included 10 patients ( 7 women , 3 men , mean age 23  6  years ) and it was 
 initiated after obtaining the approval of the ethics in research committee ( protocol number : 
 512.476 ) . the 
 exclusion criteria were as follows : presence of local infections , various systemic diseases , 
 smoking habit , use of oral contraceptives , pregnancy and lactation . all patients underwent the same surgical protocol standardized by the same surgeon 
 ( r.l.n . ) . however , the values 
 recorded for pain , swelling and trismus were assessed by a different surgeon in order to 
 conduct a blind experiment . before the laser application , the mean power of the equipment 
 was measured and calibrated using the laser check power meter instrument . intraoral lllt was applied using continuous scan mode at four different points , covering 
 the entire suppurative surgical area , which was divided into four quadrants , each of 
 1  cm area at a distance of 1  cm . preoperatively , all patients used a mouthwash with chlorhexidine ( 0.12% ) and received a 
 topical application of povidone - iodine ( 1% ) . postoperatively , all patients received 
 amoxicillin 500  mg , every 8 hours , for 7 days , ibuprofen 600  mg , every 8 hours , for 3 days , 
 and paracetamol 500  mg , every 6 hours as rescue medication for pain during the first 72 
 hours . in cases with penicillin allergy , clindamycin was selected as the antibiotic at a 
 dose of 300  mg , every 8 hours , for 7 days . in this study , , amparo , sp , brazil ) with a pen station beam area of 0.035  cm , algalnp 
 visible diode with continuous wave ( 35  mw and wavelength of 660  nm ) was used . the energy 
 applied at each point was equal to 5  j / cm / dose , continuous rate for 8 seconds , 
 as specified by the manufacturer . the formula below was used to calculate the energy density ( d ) , where the area ( a : 
 cm ) corresponds to the broadcast area of the pen tip , power ( p : w ) corresponds 
 to the maximum and constant power ( 20  mw or w 0.020 ) and the time ( t ) is measured in 
 seconds . after applying the values supplied by the manufacturer in the formula , the energy density 
 applied at each point was calculated to be 4.57  j / cm multiplied by 4 quadrants of 
 1  cm , resulting in a total of 18.28  j / cm in each session . considering previous reports of several authors , a dose of 3  j / cm up to 
 6  j / cm2 , 8 , 
 9 has a regenerative action . four consecutive daily sessions , with the first session occurring 24 hours after surgery , 
 were applied . this protocol was chosen based on the fact that the process of wound repair is 
 composed of 3 phases : inflammatory , proliferative , and remodeling phases involving the 
 formation of collagen10 , and lllt is more 
 evident in the initial stages of healing2 . the outcome variables assessed were pain , interincisal opening , facial swelling , and presence 
 of late infection . the experimental times considered in this protocol were as follows : 
 t0 ( initial time ) , t1 ( 24 h ) , t2 ( 48 h ) , t3 ( 72 
 h ) , t4 ( 96 h ) , t5 ( 120 h ) , t6 ( 144 h ) , and t7 ( 7 
 days after the surgery ) . the interincisal opening was assessed by measuring with a caliper of maximum opening between 
 the right upper and lower central incisors before surgery and in all subsequent sessions11 . to evaluate swelling , a measurement from one tragus to the opposite one all patients were instructed to register the daily intensity of pain , beginning 24 hours 
 after surgery , for seven postoperative days , using a visual analogue scale ( vas ) of 100  mm , in 
 which the score for lack of pain was 0 ( zero ) , and 100 ( one hundred ) was the score used for 
 the worst imaginary pain . all data were analyzed using graphpad 5.0 ( graphpad software , la jolla , california , usa ) . the 
 level of significance was set at p < 0.05 with a confidence interval of 95% . this study included 10 patients ( mean age : 23  6.03  years ) with asymptomatic third molars 
 ( no pain observed on the day prior to the surgery , as assessed by vas ) . all data on the interincisal opening , swelling and 
 pain intensity are shown in table 1table 1.all data on the interincisal opening , swelling , and pain intensitypost - operatory evaluationt0t1*t2t3t4t5interincisal openning ( mm)25th . quartile24.525.223.013.76.0median49.040.028.523.016.575th . quartile70.254.045.029.725.2 * statistically different from t0 , friedman test , p<0.05 . * * statistically 
 different from t0 , friedman test , p<0.05 . * * * statistically different from t0 , 
 friedman test , p<0.05 .. * statistically different from t0 , friedman test , p<0.05 . * * statistically 
 different from t0 , friedman test , p<0.05 . * * * statistically different from t0 , 
 friedman test , p<0.05 . with regard to the interincisal opening , a statistical decrease was observed 24 hours after 
 the surgery ( friedman test , p = 0.0001 ) . similarly , an increase in swelling was observed 
 when comparing the initial condition and the first postoperative day ( friedman test , p = 
 0.01 ) . therefore , it may be noted that both the swelling and interincisal opening returned 
 to normal condition 24 hours after the first lllt application . concerning the pain intensity ( assessed by vas ) , no differences were observed between the 
 first and second postoperative days ( median : 49 versus median : 40 ) . however , a reduction in pain intensity was observed immediately after the third 
 postoperative day , reinforcing the possible effect of lllt on pain ( friedman test , p = 
 0.001 ) . additionally , on the seventh day , the patients were asymptomatic . even though the 
 patients with a greater surgical duration had a slight increase in pain intensity on the 
 first day , it was not statistically significant ( spearman s correlation , p > 0.05 ) in this case series , we have focused on the local postoperative clinical factors after 
 removal of third molars , such as pain , swelling and trismus . despite the proven efficacy of 
 lllt in the prevention of these factors , its mechanism of action thus , studies with positive as well as negative results have been reported , due mainly to a 
 poorly calculated dosimetry and lack of uniformity in laser application1 , 2 , 6 . sezer et al.13 found that only the diode 
 laser with 808  nm wavelength were effective in reduction of trismus , whereas applying a 
 laser diode with 660  nm wavelength was ineffective . carrillo et al.14 showed that the incidence of trismus in the laser group 
 ( helio neon , 633  nm with energy density of 10  j / cm ) was significantly lower than 
 that in the placebo group seven days after extraction of third molars . aras and 
 gngrm15 , 16 found that irradiation with diode laser with wavelength of 808  nm 
 and 4  j / cm significantly decreases trismus . moreover , lopez - ramirez et al.2 reported 
 that lllt ( gaalas , 810  nm , energy density of 5  j / cm ) demonstrated no benefits in 
 reducing pain and trismus after removal of impacted third molars . similar results were 
 described by roynesdal and colleagues17 
 when applying lllt with 830  nm 40  mw laser at 6  j. according to gngrm and aras15 , 16 , extraction of teeth can cause spasms of 
 certain muscles , especially the masseter ; therefore , applying an intraoral laser on a small 
 area would not affect this muscle directly . however , in this study , favorable results were verified , as the reduction in trismus was 
 probably related to the relaxation effect of lllt on other masticatory muscles such as 
 masseter as well as the medial pterygoid . lpez - ramirez and colleagues2 reported 
 that lllt was not statistically effective in the reduction of trismus . amarillas - escobar et 
 al.18 conducted a similar study , but in 
 order to assess the cumulative effect of the therapeutic laser , they applied multiple daily 
 intraoral doses to the patients , immediately after surgery , and three sessions 
 post - operatively ( 24 , 48 , and 72 h ) , using lllt ( 660  nm ) . the results of this study showed 
 no significant differences in reducing pain , swelling , or trismus between the laser and the 
 control group , although better conditions were noted in the laser group 24 hours after the 
 application . however , sezer and colleagues13 found 
 that only the diode laser ( 808  nm ) was effective in biostimulation , whereas the diode laser 
 ( 660  nm ) was ineffective . however , the positive result observed at this study is probably due 
 to the onset of laser application . although lllt is considered to have analgesic effects , especially in neuralgic and muscular 
 pain , its effects on pain related to inflammation are controversial2 , 15,16,17 , 19 . there is evidence suggesting that lllt can have significant pharmacological effects on the 
 synthesis , release and metabolism of a series of biochemical mediators20 , such as increase in the production of serotonin and 
 acetylcholine in the central nervous system as well as histamine and prostaglandins 
 peripherally21 , 22 . it has also been shown that lllt induces analgesia by stimulating the synthesis of 
 endogenous endorphins ( -endorphin ) , decreasing the activity of bradykinin and c fibers and 
 changing the pain threshold21 , 22 . lllt induces morphological changes of neurons , reduces 
 the power of the mitochondrial membrane and blocks nerve conduction23 , 24 . a steady decrease in pain was observed during the application days in this study , which is 
 in agreement with the results of a previous study by markovi and todorovi25 , who reported pain reduction by 
 application of a gaalas laser after surgical removal of third molars , suggesting a 
 dose - dependent effect . moreover , it is important to state that there is a lack of knowledge concerning 
 the use of this wavelength in oral surgery . a recently published meta - analysis and 
 systematic review of the literature concluded that previous studies have important 
 methodological differences that prevent establishment of the exact dose and ideal parameters 
 for lllt26 , 27 , considering that there is a lack of standardization in the 
 parameters as well as assessment tools employed27 . in conclusion , considering the limitations of this case series , these data suggest that 
 oral application of lllt has anti - inflammatory and analgesic effects , which consequently 
 reduces postoperative complications of oral surgeries . further studies are needed , 
 especially randomized controlled clinical trials , to help elucidate the impact of laser 
 therapy after third molar extraction and establish the ideal parameters for lllt as an 
 assessment tool in this promising therapy field .
[ purpose ] this study aimed to evaluate the anti - inflammatory and analgesic effects of 
 intraoral application of low - level laser therapy ( 660  nm ) to control pain , swelling and 
 interincisal opening following the extraction of mandibular third molars . 
 [ subjects and 
 methods ] ten patients underwent removal of lower third molars using the same surgical 
 protocol and pharmacological approach . in the postoperative period , all patients received 
 four consecutive daily sessions of low - level laser therapy , beginning 24 hours after the 
 surgery . 
 intraoral applications using the diode laser with 660  nm wavelength in the 
 continuous scan mode were performed covering the entire surgical area , which was divided 
 into four quadrants , each of 1  cm2 area at a distance of 1  cm . 
 the energy 
 applied at each point was 5  j / cm2 during 8 seconds . 
 [ results ] the swelling and 
 interincisal opening returned to normal 24 hours after the first low - level laser therapy 
 application ( friedman test ) . 
 moreover , the pain intensity was reduced on the third 
 postoperative day , according to the friedman test . 
 [ conclusion ] low - level laser therapy 
 ( 660  nm ) , at the dosimetry used in this study , was effective in reducing postoperative 
 pain and swelling following oral surgery .