Red Light Therapy for Pulpitis: Scientific Evidence

Trimming away the inflamed top part of the nerve and then capping it, a 2024 randomized controlled trial in India compared Biodentine alone, Biodentine with a freeze-dried platelet concentrate, and Biodentine with low-level laser therapy (LLLT) in 120 adult molars with irreversible pulpitis. The laser group had a 660 nm laser at 100 mW for 3 minutes, held 2 mm from the exposed nerve, and the teeth were followed for a year. At 1 week, pain was highest with Biodentine alone, lower with the platelet concentrate, and lowest with LLLT, with painkiller use following the same order, but success rates did not differ significantly between the 3 groups. The authors concluded that long-term success of this nerve-saving approach remains uncertain.

Among 86 children aged 8 to 13 whose young permanent teeth had the nerve treated and sealed with Biodentine, a 2024 observational study from Poland looked back at whether photobiomodulation (PBM) eased cold sensitivity afterward. 43 teeth received a 635 nm diode laser at 100 mW, 200 mW/cm², and 4 J in total (40 seconds at 100 mW) over the gum at the root tip, right after treatment and again 24 hours later, and 43 did not. Only the laser teeth showed significantly lower cold sensitivity at 6 and 24 hours and at 1 week and 1 month, but by 3 months the 2 groups no longer differed, and both had improved over time. Further trials against a placebo with random assignment were called for.

660, 808, and 904 nm lasers and a 700 to 1100 nm LED were tested on the same 93 healthy premolar teeth in 26 adults aged 22 to 63 in a 2024 clinical trial from Australia. Each light was applied over 30 seconds at each of the cheek and tongue sides of the crown, at 100 mW and 6 J, on a separate day, and an electric pulp test measured how much current the tooth could take before it was felt at 1, 2, 5, and 20 minutes. All 4 light sources appeared to raise the pain threshold significantly at 5 minutes, with the effect peaking at 2 to 5 minutes and gone by 20, and the LED worked best, followed by the 904 nm, 808 nm, and 660 nm lasers. 29 of 132 light applications caused some discomfort, none of them with the LED, and the 904 nm laser was the most likely to.

Whether lasers improve the capping of exposed tooth nerves in adult teeth was the question a 2023 meta-analysis from India set out to answer. Of 45 studies found, 9 were reviewed and 7 pooled, covering 715 patients and lasers of several kinds, from a 632.8 nm helium-neon and an 808 nm diode to erbium lines of 2,940 nanometres. Teeth capped with laser help were far less likely to fail clinically or on X-rays, with the odds of failure about a quarter of those without laser, a difference the analysis found significant. The authors concluded that capping gives better results with laser support while noting that some trials described their methods poorly.

Researchers in Sudan tested a 980 nm diode laser before the numbing injection in 49 patients with painful irreversible pulpitis in a 2023 randomized controlled trial. The laser group had the crown of the lower molar treated for 20 seconds at 800 mW and 15 J/cm² near the gum line on the cheek side, while the placebo group had the device held in place and switched off. Compared with the switched-off device, the laser appeared to produce significantly lower pain scores during drilling and nerve removal, and fewer laser patients needed an extra injection. The laser before anesthesia was judged useful for cutting discomfort and extra injections during root canal work.

Published in 2023, this narrative review from India explored how low-level laser therapy (LLLT) is used in root canal dentistry and how it acts on cells and tissue. It covered lasers from 600 to 1300 nm and described LLLT as non-invasive, painless, and drug-free. 3 areas of promise were named for LLLT: sensitive teeth, faster wound healing, and less pain after root canal treatment, with the authors urging care over laser safety and more clinical trials.

A split-mouth design gave each child 1 baby molar treated with formocresol and 1 with laser photobiomodulation (LPBM) after nerve trimming in a 2021 randomized controlled trial from India. 68 baby molars in children aged 4 to 7 were treated, with the laser teeth receiving 660 nm at 36 mW for 4 minutes, and outcomes were checked clinically and on X-rays at 9 months. Clinical success rates were close, at 97.05% with formocresol and 94.1% with the laser, a difference that was not statistically significant. LPBM was put forward as a drug-free alternative to formocresol in baby teeth.

Researchers in 2021 tested whether an 810 nm low-level laser could numb the tooth nerve in a randomized controlled trial from Iran. 20 people had an electric pulp test to record how their teeth responded, then received the real laser at 200 mW for 30 seconds and 6 J at 1 visit and a sham probe at a second visit a week later. Pain provoked by the electric test appeared significantly lower after the real laser than before it, while the sham produced no significant change, and age and sex made no difference. The laser was called a powerful tool for inducing numbness that may also ease fear of dental work.

2021 brought an observational study from Turkey that looked back at patient records to see whether photobiomodulation therapy (PBMT) eased cold sensitivity after an exposed tooth nerve was capped with MTA (a standard sealing cement). Of 123 capping procedures on file, 72 permanent teeth qualified, split between those given a 1064 nm laser at 1 W for 1 minute held 1 mm away, and those not, with cold sensitivity scored before and at 6 hours, 1 day and 1 week. At day 7, sensitivity appeared significantly lower in the laser teeth, though not at 6 hours or 1 day, and the laser group’s drop over the week was significantly greater even though both groups improved. PBMT was described as an effective way to improve comfort after capping.

57% of patients given low-level laser therapy (LLLT) on top of the standard lower-jaw nerve block had successful numbing, against 34% with the block alone, in a 2021 randomized controlled trial from Turkey. 88 patients with painful irreversible pulpitis in a lower molar were split into 2 groups, and the laser group had a 940 nm laser at 500 mW for 30 seconds at the root tips, held about 1 cm away, before the 4% articaine injection. The difference was statistically significant, yet the authors concluded that even with the laser, the numbing was not complete for everyone.

Across 75 patients with a molar in painful irreversible pulpitis, a 2020 randomized controlled trial in Iran tested where low-level laser therapy (LLLT) works best for pain after a single-visit root canal. 25 patients had a sham laser, 25 had an 808 nm laser at 100 mW for 80 seconds on the cheek side only, and 25 had it for 80 seconds on both the cheek and tongue sides, with pain scored at 4, 8, 24, and 48 hours. 1-sided treatment never differed significantly from placebo, whereas the 2-sided group had significantly less pain than placebo at every time point, beat the 1-sided group at 8 hours, and took significantly fewer painkillers than the placebo group.

Comparing a sham laser, a laser used inside the root canal, and low-level laser therapy (LLLT) from outside, a 2019 clinical trial from Turkey treated 39 patients (21 men and 18 women) having a root canal. Each group of 13 received a 970 nm diode laser at 10 mW or a sham, and researchers measured a nerve-signaling marker of inflammation in gum fluid around the treated tooth and the matching untreated tooth before and 1 week after treatment. The trial reported that in the sham group the marker rose significantly more at the treated tooth than at the untreated tooth, whereas in both laser groups the 2 teeth did not differ. Both laser approaches were said to calm the inflammatory response.

160 baby molars in 40 children aged 3 to 9 were treated in a 2018 randomized controlled trial in Iran comparing 4 nerve-trimming techniques. Each child contributed 4 teeth, each randomly assigned to 1 of formocresol, ferric sulfate, calcium-enriched mixture (CEM) cement, or CEM preceded by a 632 nm laser at 4 J/cm² for 2 minutes 15 seconds, with checks at 6 and 12 months. According to the trial, no significant differences emerged, with 12-month clinical success of 100% for formocresol, 95% for ferric sulfate, 97.5% for CEM, and 100% for laser plus CEM. CEM with or without laser was judged a safe and successful option alongside the standard methods.

Whether a laser pulse before the numbing injection makes anesthesia deeper in teeth with painful irreversible pulpitis was the question a 2018 randomized controlled trial in Iran set out to answer. 44 patients needing root canal treatment on a lower molar were split, with 22 receiving a 980 nm diode laser at 15 J/cm² for 20 seconds on the cheek side of the tooth before the standard lower-jaw nerve block and 22 receiving none. Fewer patients in the laser group needed an extra injection to get through the drilling, which was its measure of success. PBM before anesthesia was concluded to deepen the numbing.

20 of 40 baby molars from 29 children aged 4 to 7 were treated with low-level laser therapy (LLLT) instead of MTA (a standard sealing cement) after nerve trimming in a 2016 randomized controlled trial from India. All 40 teeth had the standard nerve-trimming procedure, after which 20 were sealed with MTA and 20 were treated with a 780 to 830 nm laser, and the children were seen at 3, 6, and 12 months. At 12 months, laser success had slipped to 80% from 95% at 3 months and 85% at 6 months, while MTA held 94.7% throughout, a gap that did not reach statistical significance. LLLT was concluded to be a possible option for baby-tooth nerve treatment with success comparable to MTA.

Baby-tooth nerves treated with a laser before calcium hydroxide appeared the least inflamed under the microscope, according to a 2015 randomized controlled trial from Brazil. 20 baby molars needing the nerve trimmed were split among diluted formocresol, calcium hydroxide, a 660 nm InGaAlP laser at 10 mW and 2.5 J/cm² for 10 seconds followed by zinc oxide eugenol, and the same laser followed by calcium hydroxide, and the teeth were examined after they fell out naturally. Inflammation was significantly lowest with laser plus calcium hydroxide, calcium hydroxide alone produced the most new hard tissue and orderly cells, and formocresol caused the most internal root wear. Longer clinical follow-up was called for.

According to a 2013 review from Iran, low-level lasers work without heating the tissue and are used in dentistry mainly to reduce pain. The review defined these lasers as usually under 250 mW, with the key being an intensity below 670 mW/cm², and described their uses around the teeth, roots, jaw joint, and nerves in root canal work. It outlined proposed ways lasers may reduce pain and summarised studies on the subject rather than reporting its own results.

In 2011, a case report from Taiwan described 1 patient whose molar with pulpitis and severe gum damage was removed, treated, and put back with laser help. The tooth was extracted and cleaned with an Er:YAG laser, and an 810 nm diode laser was applied for biostimulation before the extraction and right after replanting, with follow-up over 3 months. The authors wrote that the patient reported no pain after the laser treatment and that follow-up showed uneventful healing and excellent bone regrowth. Pairing the 2 lasers was suggested to improve disinfection and healing in such replantations, though this is a single case.

2 women whose 8 premolars were due to be removed for braces took part in a 2007 randomized controlled trial in Brazil on red laser after cavity drilling. A small cavity was drilled in each tooth, and 1 group of teeth had a 660 nm GaAlAs laser at 30 mW and 2 J/cm² shone straight into the cavity once before filling, while the other group was filled without laser. Under an electron microscope 4 weeks later, the laser-treated teeth showed nerve-side cells and collagen fibers more orderly and closer to normal than the untreated teeth, resembling 2 healthy teeth examined alongside. The authors suggested that the laser speeds recovery of the tooth structure next to the nerve.

Success rates of 90% with laser and 80% without came out of a 2025 clinical trial in India on capping tooth nerves exposed by decay. 40 patients were split into a group whose exposed nerve was capped with calcium hydroxide and a group whose cavity was first disinfected with sodium hypochlorite for 1 minute, then treated with a 635 nm diode laser at 100 mW for 1 minute, and filled with composite, with pain, nerve response, and X-rays checked at 1, 3, and 6 months. The higher success with the laser approach fell short of statistical significance and was attributed to the laser’s stimulating effect on tissue. Combining disinfection and PBM was suggested as promising, pending further research.

14 of 390 studies qualified for a 2024 meta-analysis from India comparing low-level laser therapy (LLLT) with formocresol for nerve trimming in children’s baby molars. The included randomized trials covered children aged 3 to 10 and lasers from 600 to 1000 nm, and the pooled results were weighed for bias. No significant difference appeared between laser and formocresol in clinical or X-ray success at 6 to 9 months or at 12 months, yet the studies carried a high risk of bias in patient selection and treatment. LLLT was described as a good alternative for cases of reversible pulpitis.

Across 151 baby molars in 82 children aged 5 to 8, a 2022 randomized controlled trial from Turkey compared calcium hydroxide nerve treatment with and without photobiomodulation therapy (PBMT) against formocresol and MTA (a standard sealing cement). In the PBMT group, an 820 nm diode laser at 10 mW and 2.5 J/cm² was applied to each nerve stump for 12 seconds at 1 mm before the calcium hydroxide, and all teeth were checked at 6 and 12 months. 97% clinical success at 12 months went to formocresol and MTA alike, against 87% for calcium hydroxide with the laser and 71% for calcium hydroxide alone, with only the laser-free calcium hydroxide group significantly behind the 2 standard methods. The authors concluded that the laser raised calcium hydroxide’s success but not to a level that could replace MTA or formocresol.

A double-blind split-mouth design gave each of 30 adults a 904 nm laser on 1 upper premolar and a sham on the other in a 2016 randomized controlled trial from Australia. The 18 men and 12 women, average age 22, had a GaAs diode laser at 30 mW and 25 Hz for 1 minute and 3.6 J/cm² on the tooth or the gum beside it, with an electric pulp test taken 2 minutes before and immediately after. 98.1% of sham-treated sites stayed within 10% of their starting reading, whereas 52.8% of laser-treated sites changed by more than 10%, most becoming less sensitive but some more so, a difference the trial found significant. No adverse events or discomfort were reported during or after the laser.

When researchers in Brazil compared 4 ways of treating the exposed nerve in children’s baby molars, their 2015 clinical trial included 60 teeth in children aged 5 to 9. The teeth were treated with diluted formocresol, calcium hydroxide, a 660 nm laser at 10 mW and 2.5 J/cm² for 10 seconds in contact, or the laser followed by calcium hydroxide, with checks at 6, 12, and 18 months. 100% of formocresol teeth were successful on X-rays at 18 months against 66.7% with calcium hydroxide, 73.3% with laser alone, and 75% with laser plus calcium hydroxide, while every group succeeded on clinical examination. The authors concluded that the laser may be considered an add-on alternative, with laser before calcium hydroxide giving satisfactory results.

No reduction in pain after emergency nerve removal followed low-level laser therapy (LLLT) in a 2026 randomized controlled trial from Brazil. 70 patients with painful irreversible pulpitis in a permanent tooth were split into 35 who received an 808 nm GaAlAs laser at 100 mW for 1 minute in contact after the emergency treatment and 35 who did not, with pain, bite sensitivity, and painkiller use tracked. Pain eased over time in both groups, but at 12 and 24 hours it was higher in the laser group, and over the whole follow-up the laser made no significant difference. The authors concluded that adding LLLT was not associated with less pain in this emergency setting.

Comparing MTA (a standard sealing cement) alone with MTA after a low-power or a high-power laser, a 2022 randomized controlled trial in Iran treated 63 lower baby molars with partial nerve trimming. The 3 groups of 21 had MTA placed over the nerve stump either directly, after a 660 nm laser at 200 mW, or after an 810 nm laser at 1 W, and were checked for clinical and X-ray problems for 18 months. At 18 months, clinical success stood at 100% for MTA alone and MTA after the low-power laser, but 87.5% with the high-power laser, and X-ray success at 87.5%, 88.2%, and 68.7%, yet the trial found none of these differences statistically significant. Adding either laser was concluded to make no significant difference to success.

Among 60 patients arriving with the severe pain of irreversible pulpitis, a 2016 randomized controlled trial from Brazil tested laser phototherapy (LPT) against a placebo and no treatment. 4 groups of 15 received nothing, a sham laser, or a 780 nm laser at 40 mW at either 4 or 40 J/cm² at 2 points for 4 or 40 seconds each, with pain rated immediately and 15 minutes later before emergency root canal treatment began. The placebo group and both laser groups reported roughly 42 to 45% less pain than no change, but neither laser dose differed from placebo, and the low-dose laser group needed extra anesthetic more often. The authors concluded that LPT did not show a positive effect on pulpitis pain.