Red Light Therapy for Oral Postoperative Pain: Scientific Evidence

A triple-blinded design was used in a 2019 clinical trial from the Islamic Azad University in Iran to test a 650 nm low-level laser (LLL) after advanced implant surgery. 30 patients aged 25 to 65 who needed a bone graft or sinus-floor lift at the same time as their implants were split into a laser group, in which the area around each implant was treated with the 650 nm laser, and a placebo group, which received the same procedure for the same time without active light, before pain, facial swelling, and wound healing were assessed. Pain levels were clearly lower in the laser group, facial swelling eased more on days 3 and 7 with the laser, and wound healing was further along by a statistically significant margin. Laser treatment as an add-on seemed to shorten and soften pain and swelling after these complex operations.

A 2019 randomized controlled trial in Manaus, Brazil evaluated photobiomodulation therapy (PBM) with low-level laser light for pain after root canal treatment of lower back teeth with an irreversibly inflamed nerve. 60 patients treated by a single operator were randomly split into a group that received 808 nm light at 100 mW and 90 J/cm² for 100 seconds immediately after the root canal work and a group that received the treatment alone, with a blinded second examiner recording pain on 2 scales at 6, 12, and 24 hours. Researchers found that fewer patients in the light group had pain at 6 hours and at 24 hours, and the 24-hour difference held after accounting for sex and for filling material pushed past the root tip. Pain was more intense in patients whose filling material had been pushed out of the root, whichever group they were in.

30 patients aged 25 to 65 who were having dental implants placed took part in a 2018 clinical trial of low-level laser therapy (LLLT) at the Islamic Azad University in Isfahan, Iran. The trial split them into 2 groups, with the laser group having the operated area treated with an 830 nm laser at 5 J/cm² for 8 seconds per point immediately after surgery, at 72 hours, and at 1 week, and the placebo group receiving the same handling without the beam, before pain, facial swelling, and wound healing were compared. Researchers reported reduced pain severity and duration, lower facial swelling at 7 days, and more advanced wound healing on days 3, 7, and 14 in the laser group.

This 2018 randomized controlled trial in Turkey evaluated low-level laser therapy (LLLT) for pain after root canal treatment of lower back teeth with a painful infection at the root tip. 42 patients received treatment with a reciprocating instrument system and were randomly assigned by a web program to no laser, a mock laser, or a 955 to 985 nm laser at 500 mW applied over the root tip for 20 to 30 seconds, then rated pain on days 1, 3, 5, 7, and 30, along with pain on tapping the tooth. Only the LLLT group showed lower pain than both the control and placebo groups on days 1 and 3, and the difference held up statistically. According to the trial, pain on tapping did not differ among the 3 groups.

26 patients, aged 23 to 63, who had gum surgery on both sides of the lower jaw reported less pain on the side treated with a 940 nm diode laser in a 2018 randomized controlled trial from Sari, Iran. In the split-mouth design, 1 side received the laser at 500 mW and 500 mW/cm², delivering 20 to 40 J/cm² over 112 seconds on the cheek and tongue sides of the gum, immediately after surgery and on the next 2 days, while the other side had the same surgery without it, and patients logged pain and painkiller use nightly for 1 week. On day 1, pain did not differ between the sides, but from day 2 to day 7 the trial found less pain on the laser side and, from day 3 to day 7, fewer painkillers taken, both by margins that held up statistically.

88% of pain scores at laser-treated extraction sites came in below 1 on a 10-point scale in a 2017 randomized controlled trial of low-level laser therapy (LLLT) after removal of impacted lower wisdom teeth in Abu Dhabi, United Arab Emirates. The double-blind, split-mouth trial enrolled 30 healthy patients aged 19 to 39 with a mean age of 29.5, 53.3% of them women, had the same surgeon remove 1 wisdom tooth from each side 3 weeks apart, and after stitching applied an 810 nm diode laser at 100 mW, 710 mW/cm² and 32.86 J/cm² for 30 seconds at 3 points, delivering 9 J in all, to 1 randomly chosen side while the other side received the same handling with the beam off. 87% of untreated sites scored between 2.29 and 6.14, the laser effect on pain held up statistically, laser sides needed no painkillers for the first 4 days, compared with a peak of 2.83 tablets a day on control sides, and mouth opening was clearly wider on laser sides on days 1 and 7. Pain on the laser sides rose mildly after day 4, and women and patients with harder extractions reported more pain regardless of treatment.

In 2017, a randomized controlled trial in Erzurum, Turkey evaluated low-level laser therapy (LLLT) for pain after a repeat root canal treatment on lower back teeth with infection at the root tip. It enrolled 36 patients, among whom 18 received a 955 to 985 nm laser at 500 mW and 2860 mW/cm² for 30 seconds over the root tips after the procedure, and 18 received a mock treatment. The pain was scored under 50 on a 100-point scale before treatment and was followed for 7 days after treatment. For the first 4 days, the laser group reported less pain than the placebo group, but from day 5 to day 7 the trial found no difference between them. Fewer laser patients needed painkillers, and no patient reported pain during the laser application itself.

Pain 24 hours after surgery scored 2.3 in patients given low-level laser therapy (LLLT) against 4.19 in patients given drug therapy, in a 2017 randomized controlled trial of 44 people having an impacted lower wisdom tooth removed in Ahvaz, Iran. The trial applied a 980 nm laser at 300 mW for 60 seconds, delivering 18 J, at points inside the mouth around the operated area and on the face over the chewing muscle of the jaw, immediately after surgery and again the same day, and measured pain, swelling, and maximum mouth opening at 24 hours and 1 week. Only pain separated the groups, with the laser group at 0.13 against 1.43 at 1 week and both differences holding up statistically, while swelling did not differ at either check. LLLT seemed useful for pain and only slightly helpful for swelling compared with drug therapy.

When a team in Italy looked back at records from 45 patients who had impacted lower wisdom teeth removed, a 2017 observational study asked whether giving low-level laser therapy (LLLT) before surgery added anything to giving it only afterward. The patients fell into 3 groups: 1 with routine care only, 1 given a 980 nm laser at 300 mW for 3 minutes, delivering 54 J, immediately after surgery and again at 24 hours, and 1 given the same laser immediately before and immediately after the extraction, with the data analyzed by regression. Researchers found that both laser groups had fewer problems with pain, swelling, and jaw stiffness than the untreated group, and that only the group treated before surgery used significantly fewer anti-inflammatory painkillers in the first 24 hours. Treating before surgery seemed to add to the pain relief, while swelling and jaw stiffness improved whichever timing was used.

Published in 2017, this placebo-controlled clinical trial from Charles University in Prague, Czech Republic, looked at whether low-level laser therapy (LLLT) after removal of impacted lower wisdom teeth under general anesthetic could be tracked through markers in saliva and a heat-sensing camera rather than through pain scores. The trial covered 213 impacted wisdom teeth in 57 patients: 14were 4 treated with an 830 nm diode laser in contact at 270 mW, 4200 mW/cm², and 46 J/cm² for 11 seconds over 3 days, and 7were 4 given a placebo, and measured a protective antibody and an antibacterial enzyme in saliva before and after treatment. The antibody level fell further after laser treatment, from 546.91 to 304.91 mg/L, than in the placebo group, where it fell from 602.25 to 425.62 mg/L, and the enzyme level was also lower after treatment, the researchers reported. Facial temperature over the treated and placebo sides differed by only 0.2°C, so the deep wounds appeared to have no effect on skin heat.

Researchers in Turkey compared low-level laser therapy (LLLT) given inside the mouth with the same therapy given through the skin of the face in a 2017 randomized controlled trial of pain after lower wisdom tooth removal. The study at 2 centers enrolled 60 patients with a fully bone-covered wisdom tooth in a similar position on each side, and split them into 30 who received 830 nm laser light at 100 mW and 3 J/cm² inside the mouth and 30 who received it through the cheek. In each patient, 1 side was treated immediately before and after extraction while the other side was given an inactive laser, and pain and socket healing were followed for 1 week. Only the intraoral group showed a reduction in pain compared with both the through-the-skin group and placebo, while the number of unhealed sockets at 7 days did not differ. The authors concluded that a single intraoral session works better than application through the skin, possibly because skin and mouth lining absorb the light differently.

Researchers in 2016 tested superpulsed low-level laser therapy (SLLLT) against no treatment for pain and swelling after both lower wisdom teeth were removed in 1 operation, in a randomized controlled trial at the University of Turin, Italy. 25 patients each had 1 randomly chosen side treated with a diode laser combining 635 and 904 to 910 nm light immediately after surgery and again at 24 and 48 hours, delivering 180 J per 15-minute session, while the other side served as the control. Pain and swelling were scored on 0-to-10 scales alongside measurements between fixed points on the face. Researchers found that pain and swelling were significantly lower on the treated side, with the difference in pain clearest at 48 hours when symptoms on the untreated side peaked and the benefit held until day 5. Patients tolerated the treatment well, and no side effects were reported.

Whether low-level laser therapy (LLLT) could reduce pain and swelling after removal of impacted wisdom teeth was the question a 2016 randomized controlled trial in Mashhad, Iran set out to answer. In each of 40 patients with a symmetrically impacted lower wisdom tooth on both sides, 1 side was randomly assigned to LLLT and the other to a placebo. The treated side received a 660 nm laser at 200 mW and 6 J at 4 points inside the mouth, followed by an 810 nm laser at 200 mW and 6 J at 3 points on the face, with the facial treatment repeated on days 2 and 4, and pain was tracked for 7 days with swelling measured on days 2, 4, and 7. The researchers reported that only the laser side showed lower pain at every time point and less swelling on days 2, 4, and 7, with both differences holding up statistically.

A split design in which each patient had 1 lower wisdom tooth removed with low-level laser therapy (LLLT) and the other removed 21 days later without it was used in a 2016 randomized controlled trial from Curitiba, Brazil. 22 patients whose 2 wisdom teeth sat in similar positions on X-ray received a single dose of 780 nm light at 10 mW and 7.5 J/cm² at 10 points, 4 inside the mouth close to the socket and 6 on the face along the chewing muscle of the jaw. Pain, swelling across the cheek, and mouth opening were recorded before surgery, immediately after, at 48 hours, and at 7 days. At 48 hours and again at 7 days, the laser-treated side showed reductions in pain, swelling, and jaw stiffness compared with the untreated side, according to the study.

Comparing photobiomodulation (PBM) given immediately with the same treatment delayed by 2 days, a 2015 randomized controlled trial in Jeddah, Saudi Arabia asked which timing better limited pain, swelling, and jaw stiffness after removal of horizontally impacted lower wisdom teeth. 80 patients whose teeth sat clear of the main nerve canal in the lower jaw were divided into an immediate group treated right after surgery and on day 3 and a delayed group treated on days 2 and 4, with every session delivering 171 J from a 4 W laser at 830 nm over 2 minutes through a 2.8 cm² spot. The immediate group showed less pain, swelling, and jaw stiffness than the delayed group, so earlier treatment appeared to work better.

10 patients with a mean age of 23 who had a lower wisdom tooth removed under the same surgical and drug protocol took part in a 2015 observational study of low-level laser therapy (LLLT) in Brazil. Starting 24 hours after surgery, every patient received 4 daily sessions of 660 nm light inside the mouth, scanned across 4 squares of 1 cm² over the surgical area from 1 cm away at 5 J/cm² for 8 seconds per point, with the laser at 20 to 35 mW. Swelling and mouth opening returned to normal within 24 hours of the first session. Researchers found that pain intensity was reduced by the third day after surgery.

A 2015 randomized controlled trial in Parma, Italy evaluated low-level laser therapy (LLLT) for pain and swelling after surgical removal of impacted lower wisdom teeth. 59 patients were allocated to 17 who received LLLT plus standard drugs, 17 who received drugs only, and 25 who received LLLT on 1 side plus drugs. The laser was a diode combining pulsed 910 nm and continuous 650 nm light, delivering 240 J over 15 minutes at theoretical doses of 480 and 31 J/cm² per minute, given right after surgery and about 12 hours later. By the time patients left the hospital, pain scores already differed between groups, and swelling measured at fixed facial landmarks was lower with LLLT at every check, both by margins the authors called statistically significant, the researchers reported.

Pain in the first 3 days after wisdom tooth surgery appeared lower with low-level laser therapy (LLLT) than with a placebo laser or no laser, according to a 2015 systematic review and meta-analysis from Guangzhou, China. The review pooled 6 randomized controlled trials with 193 participants who had impacted lower wisdom teeth removed, covering wavelengths from 632.8 to 980 nm, power from 8 to 400 mW, and doses of 4 and 10 J/cm², and rated 3 trials as moderate risk of bias and 3 as high risk. Pain scores fell 2.63 points more with LLLT on day 1, 2.34 on day 2, and 3.40 on day 3, and mouth opening was 4.94 mm wider in the first 3 days and 3.24 mm wider at day 7. It also found that treatment on the face, alone or combined with treatment inside the mouth, reduced facial swelling by a margin that held up statistically. Researchers concluded that the evidence was limited because the trials differed in methods and carried risk of bias.

2 children treated with low-level laser therapy (LLLT) after minor mouth surgery needed no pain medication afterward, in a 2014 observational study from Brazil. 1 child had an extra tooth removed, and the other had the small fold of tissue joining the lip to the gum cut. LLLT was applied with 685 and 830 nm light at 35 and 100 mW and 30 and 60 J/cm² for 17 and 49 seconds per session, over 3 sessions in 2 days. Less swelling and pain followed the treatment, according to the report, and wound healing was judged satisfactory at follow-up. Both the children and their parents accepted the laser treatment well.

When researchers in Chennai, India, compared 2 systemically healthy patients who each received a gum graft for receding gums, a 2014 observational study examined whether low-level laser therapy (LLLT) could improve blood supply to the graft and reduce pain during early healing. The second patient received LLLT, with an 830 nm diode laser at 100 mW and 3 J/cm² for 60 seconds, given half an hour after surgery and again on days 3, 7 and 9, and both patients rated pain on a numerical scale on days 2, 4 and 10 while an ultrasound scan of blood flow assessed the graft on days 4 and 9. Only the laser-treated patient showed a significant rise in blood flow to the graft on days 4 and 10 and a sharp drop in pain by day 4, with no further change by day 10, so LLLT appeared to help both blood supply and pain control in early healing.

Pain scored 1.2 on the laser-treated side of the face against 3.4 on the untreated side 24 hours after corrective jaw surgery in a 2014 randomized controlled trial of low-level laser therapy (LLLT) from Brazil. 10 healthy patients who had surgery on both jaws received LLLT inside the mouth and on the face on 1 side only, using 660, 780, and 789 nm light at 20 to 70 mW and 5 to 70 J/cm² for 10 to 40 seconds per point over 4 days, while the other side had a simulated application, with swelling and pain compared between sides. By day 3, the gap in pain had narrowed to 0.6 against 2.1, and by day 7 neither side hurt, while swelling on the treated side stayed lower at days 3, 7, 15, and 30, a gap the authors reported as statistically significant. Researchers found that immediately after surgery, the 2 sides had not yet differed on either measure.

This 2014 randomized controlled trial set ozone therapy and low-level laser therapy (LLLT) against no added treatment for pain, swelling, and limited mouth opening after wisdom tooth surgery. 60 patients in Istanbul with a symptom-free impacted lower wisdom tooth (28 women and 32 men, mean age 23.5) were randomized into 3 groups of 20, and the LLLT group received 808 nm light at 100 mW and 4 J/cm² for 2 minutes, delivering 12 J, at the surgical wound and over the chewing muscle of the jaw, over 7 days. Pain levels and the number of painkiller tablets taken were lower in both the ozone and LLLT groups than in the control group. Jaw stiffness was significantly less in the LLLT group than in the other 2 groups, and only LLLT reduced swelling, while both therapies were associated with better quality of life scores.

Laser light at 90 mW on its own and at 50 mW after a light-activated antimicrobial dye were tested against no added therapy in a 2013 randomized controlled trial of 150 patients having a lower wisdom tooth surgically removed in Zagreb, Croatia. 50 patients received antimicrobial photodynamic therapy (APDT), with the dye applied before stitching, washed off after 60 seconds, and then lit with 660 nm laser light in 2 bursts of 30 seconds. 50 received low-level laser therapy (LLLT) at 660 nm in 2 bursts of 90 seconds before stitching, and 50 had no additional treatment, with checks on days 3 and 7. The authors concluded that both laser approaches reduced pain, swelling, bad breath, and painkiller use and improved wound healing compared with the control group, with the APDT group having the fewest problems.

2010 brought an observational study from Brazil of infrared laser therapy in 1 adult patient after surgery to widen the upper jaw. The adult patient, whose upper jaw was 8 mm too narrow, began treatment on the 7th day after surgery and received 8 sessions 48 hours apart, with an 824 nm diode laser in contact at 100 mW and 1.5 J/cm² for 20 seconds at each of several points across the cheeks, the base of the nose, and the roof of the mouth on both sides. After the course, no swelling or pain was observed, and X-rays appeared to show faster bone healing along the middle of the palate.

Whether low-power laser irradiation or the anti-inflammatory drug diclofenac better controlled pain after lower wisdom tooth removal was 1 of 2 questions a 2006 randomized controlled trial of 102 patients of both sexes set out to answer. The first part compared a long-acting local anesthetic with a standard one in 12 patients. In the second part, 90 patients having a lower wisdom tooth surgically removed under local anesthetic were split into 30 who received 637 nm laser light at 50 mW and 4 J/cm² after surgery, 30 who took a single 100 mg dose of diclofenac beforehand, and 30 who received only routine aftercare. Patients given the laser after diclofenac premedication showed significantly lower pain intensity than the controls. The authors concluded that a long-acting local anesthetic combined with low-power laser irradiation gave the most comfortable recovery.

15 patients who had both lower wisdom teeth removed in the same operation took part in a 1991 clinical trial, described by the authors as a pilot study, of a helium-neon laser for post-surgery pain. Each patient had 1 side of the mouth treated with the 632.8 nm laser at 10 mW for 3 minutes immediately after surgery, while the other side received the same handling with the beam switched off and served as the control. According to the study, only the treated side showed less pain on the day of surgery and on the first day after, and the gap was large enough to count.

Setting low-level laser therapy (LLLT) against placebo, no treatment, and ibuprofen across 7 randomized controlled trials, a 2019 systematic review from Sichuan University in Chengdu, China assessed pain management after root canal treatment or retreatment. The 7 trials, 5 on first-time treatment and 2 on retreatment, used diode and indium-gallium-aluminum lasers at 800 to 985 nm with doses from 8 to 85.9 J/cm², enrolled about 400 patients in all, and 6 of the 7 carried a moderate risk of bias. 3 of the studies showed that LLLT reduced how many patients had pain afterward, while most found lower pain intensity in the laser group, even though the timing of the effect varied, and 2 of the 3 studies that counted painkillers found a benefit. Researchers found the evidence promising but said firm conclusions should not be drawn until more high-quality trials are done.

15 of 45 patients received a single dose of low-level laser therapy (LLLT) right after removal of an impacted lower wisdom tooth in a 2018 randomized controlled trial from Afyon Kocatepe University in Turkey that measured facial swelling with 3D imaging. The other 30 patients, all over 17 years old, were split between a control group given routine care with ice and a placebo group given a sham treatment, while the laser group received a diode laser on the face at 300 mW and 4 J/cm² for 40 seconds, delivering 12 J. Pain in the laser group was lower than in the placebo group at every time point and lower than in the control group on day 7, while swelling and jaw stiffness showed no clear difference between the 3 groups. The authors concluded that a single dose reduced pain, and that swelling fell with the laser by too little to rule out chance.

Across 21 randomized clinical trials with 1,060 participants, a 2017 systematic review update and meta-analysis weighed low-level laser therapy (LLLT) against placebo or no treatment for pain, swelling and jaw stiffness after removal of impacted lower wisdom teeth. The pooled trials used wavelengths from 632.8 to 980 nm, doses from 3 to 85.7 J/cm², and powers from 8 mW to 40 W, and the reviewers rated the certainty of each result with a formal grading system. Pain was 1.42 points lower on a 10-point scale at 2 days with LLLT and 0.59 points lower at 7 days, mouth opening was 3.42 mm wider at 2 days and 2.30 mm at 7 days, and swelling was lower at 2 days but barely at 7 days. According to the review, LLLT probably has negligible benefits and probably does no harm, and the evidence does not support using it to reduce complications after this surgery.

2016 brought a randomized controlled trial from Inonu University in Malatya, Turkey that measured facial swelling with a 3D camera system while testing low-level laser therapy (LLLT) after removal of impacted lower wisdom teeth. 15 patients with symmetrical impactions on both sides had 1 side treated on the face over the chewing muscle of the jaw with an 810 nm laser at 300 mW and 4 J/cm² for 40 seconds, delivering 12 J, right after surgery and again on day 2, while the other side received only routine advice, including ice. By day 7, the pain level on the laser side was lower than on the control side, but at earlier checks it was not. According to the trial, swelling volume and mouth opening did not differ between the sides at any point.

Blood flow in the skin near the jaw joint appeared to change after 808 nm laser treatment, according to a 2016 randomized controlled trial from Salvador, Brazil, that measured it with a heat-sensing camera after wisdom tooth removal. It split 24 patients into 4 groups by whether the tooth had come through or was impacted and whether they received the infrared laser at 630 mW/cm² and 2 J/cm² for 3 minutes or a switched-off device, then assessed pain, swelling, and mouth opening after surgery. Swelling, pain, and mouth opening improved slightly with the laser, but none of the 3 changed by enough to rule out chance. Only the circulation measure showed a change that held up statistically.

Applying a 980 nm diode laser both inside the mouth and over the chewing muscle of the jaw right after surgery and again 24 hours later, a 2013 randomized controlled trial in Italy tested low-level laser therapy (LLLT) for pain, swelling, and limited mouth opening after removal of impacted lower wisdom teeth. 30 patients aged 18 to 30, 15 men and 15 women, were split into 15 who received the laser in continuous mode at 300 mW for 180 seconds per session, delivering 54 J from 1 cm away, and 15 who had routine care only, with all asked to avoid painkillers for 12 hours before surgery. Mouth opening on the first day after surgery averaged 2.91 cm in the laser group against 2.40 cm in the control group, and according to the study, jaw stiffness on days 2 and 7 and swelling on day 1 were clearly lower with the laser. Pain scores were also lower in the laser group at every check, 3.75 against 7.1 at 24 hours, but that gap was not large enough to rule out chance.

Among 14 adolescents having premolars surgically removed, a 2012 double-blind randomized controlled trial in Brazil tested low-level laser therapy (LLLT) for wound healing and pain. Patients in the laser group received 5.1 J (60 J/cm²) from an 830 nm diode laser at 100 mW for 51 seconds at 3 points inside the mouth, 1 cm from the tissue, immediately after surgery and again at 48 and 72 hours. The placebo group had the device applied at the same points without activation, and an independent examiner assessed healing from photographs at 2, 7, and 15 days as patients rated pain on a 0-to-10 scale. Compared with placebo, the laser group reported lower pain intensity, but the gap was too small to rule out chance at any time point, and healing was similar in both groups. The authors concluded that these laser settings neither sped healing nor clearly reduced pain.

In 2010, a double-blind randomized controlled trial in Mexico evaluated a therapeutic laser for pain, swelling, and limited mouth opening after surgical removal of impacted lower wisdom teeth. 2 groups of 15 patients were operated on under local anesthetic, and the treatment group received 4 J/cm² from an 810 nm diode laser at 100 mW in continuous mode both inside the mouth and on the face over 3 days, while the control group had standard care only. Researchers found that the laser group had less pain, swelling, and jaw stiffness, but none of the gaps were large enough to rule out chance. Patients in both groups needed rescue medication, and the control group reached for it sooner after surgery.

Researchers in 2004 tested a single low-level laser treatment against a simulated version for pain after root-end surgery, in a double-blind randomized controlled trial from Mainz, Germany. 52 healthy adults were split evenly, with 26 having the operated area treated after stitching with an 809 nm diode laser at 50 mW for 150 seconds, delivering 7.5 J, and 26 receiving a simulated treatment, then rating their pain daily on a 0-to-10 scale for 7 days. On the first day after surgery, the laser group reported significantly less pain, and although scores stayed lower for the whole week, the trial found the difference held up statistically on that day only. More work on the best dose and number of treatments was recommended.

Published in 1997, this review from the University of Queensland summarized controlled clinical studies of low-level laser therapy (LLLT) for soft tissue uses in dentistry, including pain after oral surgery. The paper covered wavelengths from 632 to 904 nm, and doses in the range of 2 to 9.3 J/cm² across the studies it drew on, and the review data listed 4,546 participants in total. Some applications appeared to benefit while others did not, and for pain after wisdom tooth removal, the review cited 1 small split-mouth study reporting less pain against 2 larger double-blind trials that found no difference from a placebo laser. LLLT may help with specific applications, but the author described it as effective for some uses only and called for randomized controlled trials.

Applying a low-level laser to acupuncture points on the ear rather than to the operated area itself, a 2018 randomized controlled trial in Sao Paulo, Brazil tested whether this could reduce pain after lower wisdom tooth surgery. 42 healthy patients had symmetrical wisdom teeth removed on both sides in 84 operations, with 1 side treated at the ear points with 650 to 670 nm light at 100 mW and 35.4 mW/cm² for 10 seconds per point and the other side given a simulated treatment, repeated at 24 and 48 hours, and pain, mouth opening, swelling, local temperature, swallowing difficulty, and signs of infection checked at 24 hours, 48 hours and 7 days. None of the measures differed between the 2 sides. Laser at ear points appeared not to prevent pain after this surgery, and any side effects were recorded and reported.

As reported in a 2017 clinical trial from Shahid Beheshti University in Tehran, Iran, researchers evaluated low-level laser therapy (LLLT) as a drug-free way to reduce pain after a repeat root canal treatment on back teeth. 61 patients had the retreatment completed in a single visit, after which the treatment group received a single dose of 808 nm light at 100 mW and 70 J/cm² for 80 seconds on the gum over the root tips, and the control group received a placebo laser, with pain scored on a 0-to-10 scale before, immediately after, and at 4, 8, 12, 24, and 48 hours. Pain scores did not differ between the 2 groups at any time point, and although regression analysis showed lower pain after the active laser, the difference was too small to rule out chance. The authors concluded that taking painkillers afterward was the 1 factor that clearly reduced pain, while age, sex, laser use, pre-treatment pain, and education level did not.

A single session of 4 J/cm² from a 940 nm diode laser, applied to the face over all the affected areas right after surgery, was tested against no laser in a 2016 randomized controlled trial at Yuzuncu Yil University in Van, Turkey. 35 outpatients with similarly impacted lower wisdom teeth on both sides had the teeth removed in 2 separate operations, with 1 side treated at 500 mW/cm² for a total of 50 J and the other left as a placebo side, and swelling, mouth opening, and self-rated pain were compared between the 2. Swelling and mouth opening looked better on the treated side, yet the trial found no difference in pain, swelling, or mouth opening between the sides that was large enough to count. The authors suggested that a single session might still help patients feel less swelling and jaw stiffness.

Among 37 children needing a baby molar removed on each side, a 2016 randomized controlled trial in Kocaeli, Turkey tested low-level laser therapy (LLLT) for pain after the extraction. The trial applied an 810 nm diode laser in continuous mode at 300 mW and 4 J/cm² for 180 seconds, 1 cm from the tissue, immediately after 1 extraction and used the handpiece switched off after the other, then had children rate pain on a faces scale and parents on a 0-to-10 scale for the first 3 evenings. Pain ratings from both children and parents ran higher after the untreated extraction on the first evening, and parents gave more painkillers that evening, but none of the differences were large enough to rule out chance. The authors concluded that LLLT after baby molar removal did not affect pain in children within the limits of the study.

No measurable effect on pain followed a single session of low-intensity laser in a 2015 randomized controlled trial of 60 patients having impacted lower wisdom teeth removed. Patients were randomly allocated to 5 groups and treated immediately after extraction with 660 or 808 nm light in contact at 100 mW, 3537 mW/cm², and 106 J/cm² for 30 seconds, delivering 12 J, then rated their pain on 2 scales at 2 and 7 days. Both pain scales gave similar results across the 5 groups at 2 and 7 days, and the trial found no benefit from 1 session under the conditions tested.

According to a 2012 randomized controlled trial from Barcelona, described as a preliminary study, researchers evaluated low-level laser therapy (LLLT) for pain, facial swelling, and limited mouth opening after removal of impacted lower wisdom teeth. The trial treated 1 side in each of 20 healthy patients (11 women and 9 men, mean age 23.35) with an 810 nm laser at 400 mW and 4 J/cm² for 32 seconds, delivering 12.8 J, while the other side had the handpiece applied without the laser switched on. The 2 sides did not differ in pain in the first hours, nor in swelling and mouth opening at days 2 and 7. At the end of the study, it found no benefit from the laser with these settings.

Researchers in Sweden evaluated monochromatic light phototherapy with a Biolight device against a placebo in a 2007 randomized controlled trial, run double-blind, of 60 adults having an impacted lower wisdom tooth removed. All patients received 6 minutes of treatment before surgery and 10 minutes after, at wavelengths of 637 to 956 nm and irradiances of 2.1 and 5.5 mW/cm², and were checked at 3 and 7 days for pain, wound healing, and the number of painkillers taken, with 1 patient excluded because the tooth removed was an upper tooth. Pain and painkiller use came out much the same in the phototherapy and placebo groups, the researchers reported.

Comparing low-level laser therapy (LLLT), a placebo laser, and no added treatment, a 2005 randomized controlled trial in Graz, Austria, followed 72 root-end surgery cases on front teeth and premolars. Cases were randomly split 3 ways, and the LLLT group received 680 nm light in contact at 75 mW and 3 to 4 J/cm² for 60 seconds during surgery and again 1, 3, and 7 days later, while a blinded examiner rated swelling, wound healing, and pain on the same days. No meaningful difference appeared between the LLLT and placebo groups. According to the study, only the untreated control group reported more severe pain, which the authors read as a prominent placebo effect.

52 of 64 patients, aged 18 to 30, provided complete data in a 1993 randomized controlled trial from the United Kingdom that tested low-level laser therapy (LLLT) after removal of an impacted lower wisdom tooth on each side. 1 randomly chosen side was treated inside the socket with an 830 nm semiconductor laser at 30 mW for 132 seconds, delivering 4 J, while the other side received an identical-looking inactive probe, and pain, swelling, and healing were compared at 3 and 7 days. Researchers found no difference in pain and swelling on day 3 between the laser and placebo sides. Healing at 7 days was also the same on both sides.

A double-blind crossover design gave 25 healthy adults both an active and a placebo soft laser in a 1993 clinical trial of pain and swelling after wisdom tooth surgery in Norway. The 14 women and 11 men, aged 18 to 30, each had identically impacted lower wisdom teeth removed in 2 separate operations by the same surgeon. 1 side received 6 J from a 40 mW laser at 820 to 830 nm before and after surgery, and the other side received a placebo laser, with swelling, mouth opening, and self-rated pain measured afterward. Swelling, mouth opening, and pain were similar on the laser and placebo sides, the researchers reported.

No difference in pain or swelling between treated and untreated sides emerged in a 1990 randomized controlled trial of helium-neon laser therapy after wisdom tooth removal. The trial in Finland enrolled 17 patients with a lower wisdom tooth embedded on each side, removed both teeth in 1 operation, and treated a side chosen by lot with the 632.8 nm laser at 8 mW and 50 Hz for 2 minutes while the other side went untreated, with swelling measured by a facial measuring device and pain rated on a 0-to-10 scale. Both sides scored alike on swelling and pain, and the investigators concluded that continuing was not justified and stopped the study early on ethical grounds.