Red Light Therapy for Tooth Sensitivity: Scientific Evidence

445 nm for 1 group of lesions, 660 nm for a second, 970 nm for a third, and a sham for the fourth were the arms of a 2024 split-mouth randomized controlled trial at a university in Egypt. The study tested low-level diode lasers on symptomatic worn notches at the gum line before filling with composite in 9 patients with 36 lesions; each lesion was prepared, irradiated, and filled. Sensitivity to cold was scored on a self-rated scale at the start and at 1 day, 14 days, and 1, 3, and 6 months, and pulp response was tested electrically at 3 and 6 months. The trial found tooth sensitivity fell in every group, significantly so from 14 days to 6 months at 660 and 970 nm and only at 6 months at 445 nm. On 12 extracted molars examined under an electron microscope, 660 and 970 nm narrowed the dentin tubules without melting them, so 660 nm worked best, then 970, with 445 nm last.

Researchers at a dental school in Brazil searched the literature up to April 2020 for clinical trials of laser therapy for dentin hypersensitivity, in a 2023 systematic review and meta-analysis. 562 publications were found, 160 read in full, 34 included, and 11 pooled, with case reports and other reviews excluded, and 2 examiners extracting data and rating risk of bias independently. Most studies, 55%, followed patients for no more than 6 months. Researchers found statistically significant differences between average pain before treatment and after 3 months with both high-power and low-power lasers, and an indirect comparison showed a greater tendency to reduce pain with high-power lasers that did not reach significance. Laser treatment was concluded effective for tooth sensitivity, whatever the type of laser, but the assessment methods varied too much for a defined protocol to be set.

23 patients with gum disease who were starting braces, and 143 sensitive teeth between them, saw dentin hypersensitivity decline over a 2023 triple-blinded randomized controlled trial at a dental faculty in Hong Kong. Teeth on 1 side of each dental arch were randomly assigned to low-level laser therapy (LLLT) at 940 nm and 800 mW, and teeth on the other side received no laser. Once the braces were fitted, patients kept diaries of their orthodontic pain, and tooth sensitivity was scored in the chair on a self-rated scale. Sensitivity generally decreased over the observation period. The conclusion suggests LLLT may help manage dentin hypersensitivity in gum-disease patients undergoing orthodontic treatment.

This 2022 randomized controlled trial at a state university in Brazil tested whether photobiomodulation (PBM) with light-emitting diodes (LED) lowers the risk of the tooth sensitivity that follows in-office whitening. 64 volunteers were divided into an LED group, which received 940 nm light at 160 mW, 16 mW/cm², and 4 J/cm² for 10 minutes alongside whitening with 35% hydrogen peroxide, and a placebo group, which had the whitening and a simulated irradiation. Whether sensitivity occurred, how intense it was on 2 self-rated scales, how many teeth were affected, and how it disturbed daily activities were recorded during whitening, immediately after it, and at 24, 48, and 72 hours, with tooth shade measured by eye and by instrument. Researchers found that LED irradiation reduced both the occurrence and the intensity of sensitivity at every time point except 72 hours, when the groups no longer differed, and that significantly more teeth were affected in the placebo group. Shade did not differ between the groups, so the light gave more comfort without costing any whitening.

In 2022, a randomized controlled trial at a dental school in Brazil compared 3% potassium nitrate gel, photobiomodulation therapy (PBM) with a low-level infrared laser, and the 2 together over 3 sessions for cervical dentin hypersensitivity. 54 patients with 303 sensitive teeth were allocated 17 to the gel, 17 to the laser, and the rest to the combination. The laser delivered 808 nm light at 100 mW and 1 J per point through a 0.028 cm² tip in contact with the tooth neck, and sensitivity was scored on a self-rated scale before treatment, after the course, and at 3 months. Pain levels fell in every group by the end of treatment, and no significant difference in score change appeared between the groups either immediately or at 3 months. They concluded the 3-session protocol effective for tooth sensitivity after 3 months, whatever the desensitizing mechanism.

Across 6 randomized controlled trials drawn from 1081 candidate articles, a 2022 meta-analysis from a dental college in India and a university in Italy tested whether near-infrared laser therapy relieves dentin hypersensitivity immediately and at 1 month. Only trials comparing the lasers with placebo or no treatment in adults were included, and their results were pooled with a random effects model. According to the pooled analysis, near-infrared laser therapy significantly reduced self-rated tooth sensitivity scores at both time points, although the 6 trials differed considerably, with heterogeneity of 96%. The effect was immediate and had not diminished at the 1-month follow-up.

60 jaw quadrants in 24 patients who had undergone gum surgery were randomly assigned to 4 treatments for dentin hypersensitivity in a 2021 double-blinded randomized controlled trial at a dental school in Iran. Group 1 had low-level laser therapy (LLLT) combining red 660 nm and infrared 810 nm light at 200 mW, and group 2 an Er,Cr:YSGG erbium laser at 0.25 W and then 0.5 W at 25 Hz for 10 seconds per tooth. Group 3 had fluoride varnish, group 4 a placebo laser, and sensitivity to a cold spray was scored on a self-rated scale before treatment, immediately after, and at 1 week. All 3 active treatments appeared to reduce tooth sensitivity significantly from the starting level while the placebo did not, but at 1 week the erbium laser scored significantly lower than both LLLT and placebo, and fluoride varnish lower than placebo. No adverse effect such as pulp death was noticed, and the erbium laser was judged the most effective option.

According to a 2021 systematic review and meta-analysis from a dental faculty in Hong Kong, low-level light therapy (LLLT) relieves dentin hypersensitivity better than placebo whether measured immediately, in the medium term, or over the long term. 6 databases were searched through December 2020 under the PRISMA standard, 2 reviewers screened independently, and 35 articles were assessed for risk of bias, with 20 randomized controlled trials pooled. The trials used wavelengths from 635 to 1064 nm at 20 mW to 1 W for 25 seconds to 2 minutes. The analysis found standardized effects of 1.09 immediately, 1.32 at interim checks, and 2.86 for persistent relief in favor of LLLT over placebo, with substantial variation among the trials. LLLT showed no advantage over other in-office desensitizing treatments apart from fluoride agents, and the reviewers called for low-bias trials with consistent settings and long follow-up.

No difference between potassium oxalate gel and a low-power laser remained after 4 applications over 3 weeks in a 2020 randomized controlled trial at a university in Brazil of cervical dentin hypersensitivity in worn notches at the gum line. 74 participants with 389 such notches were allocated to oxalate gel, to an 808 nm GaAlAs laser at 100 mW and 60 J/cm² for 16 seconds, held 1 mm from the tooth, or to a third group whose treatment is cut from the record. Sensitivity to touch and to a puff of air was scored after each application. After the first application, the gel group and the third group had less sensitivity to touch than the laser group, and after the second application, the third group led in both tests. Tooth sensitivity appeared to fall in every group over the 3 weeks, so oxalate gel acted faster, while the laser reached the same result by the end of the course.

Whether a newly designed photobiomodulation toothbrush could treat dentin hypersensitivity at home as well as fluoride varnish does in the clinic was the question of a 2019 pilot randomized controlled trial by a team based at a university hospital in Germany. 30 patients with receding gums and sensitive exposed roots were assigned in equal groups to fluoride varnish, the toothbrush, or both. The brush delivered 660 nm light in continuous mode at 40 mW for 30 seconds per spot, 1.2 J per spot, at 200 mW/cm² and 6 J/cm². Pain and tooth sensitivity were scored on a self-rated scale with a probe and a puff of air at the start and 1 month after treatment began. The trial found a significant reduction in all 3 groups, with a significantly greater reduction in the combination group, and the authors described the toothbrush as a convenient, safe, and effective home treatment.

90 patients who reported dentin hypersensitivity, half of them with moderate to fairly severe fluorosis, the enamel mottling caused by excess fluoride in childhood, completed a 2019 double-blind randomized controlled trial. Each half was subdivided into 3 groups to receive 5% potassium nitrate, low-level laser therapy (LLLT) at 810 nm and 1 W, or both, and every patient had at least 1 tooth scoring 3 or more on a self-rated scale. Sensitivity to a puff of air, a cold stimulus, and a calibrated scratching device was checked at the start, 30 minutes after treatment, and at 1, 4, and 12 weeks. The combination proved more effective than either treatment alone at every time point against the starting scores, and only the combination showed a significant result at 12 weeks in the fluorosis group. The authors concluded that LLLT plus potassium nitrate eased tooth sensitivity throughout, with the larger effect in fluorotic teeth.

After 1 month of follow-up, the combination of photobiomodulation (PBM) and CPP-ACPF, a milk-protein calcium phosphate paste with fluoride, had reduced dentin hypersensitivity more than any other treatment in a 2019 randomized controlled trial at a dental school in Brazil. 80 sensitive teeth in 24 patients were randomized to 4 groups: placebo paste with sham laser, CPP-ACPF with sham laser, placebo paste with active laser, or CPP-ACPF with active laser, each over 3 sessions. The laser was an 808 nm diode at 60 J/cm² for 16 seconds. Tooth sensitivity to a probe and to a puff of air was scored on a self-rated scale after each session and at 1 month, alongside a questionnaire on how the condition affected daily life. Every group appeared to improve on both stimuli by 1 month, but only the combination group differed significantly from the rest on the air test and on the quality-of-life questionnaire.

Testing low-level laser therapy (LLLT) alongside a 5000 ppm fluoride toothpaste against the sensitivity that follows tooth whitening, a 2018 double-blind split-mouth randomized controlled trial at a university in Brazil treated 25 volunteers over 4 weekly bleaching sessions with 35% hydrogen peroxide. The upper and lower quadrants on 1 side received LLLT before each bleaching and fluoride after it, and the other side had the laser tip placed without light, then the same fluoride. The laser delivered 808 nm light at 60 J/cm² and 3750 mW/cm² for 16 seconds at 2 points on each incisor, canine, and premolar, at the neck and the middle of the tooth. Sensitivity was recorded at each session. The trial found a significant difference in the incidence of sensitivity pain between the 2 sides at different evaluation times, so teeth treated with laser and fluoride showed less tooth sensitivity than teeth given fluoride alone.

A 3-arm design with 135 teeth from 22 patients underpinned a 2018 clinical trial at a dental school in Iran comparing an 810 nm diode laser, a 1064 nm Nd:YAG laser, and a dentin bonding agent for dentin hypersensitivity. Group 1 teeth had the diode at 200 mW for 30 seconds, group 2 the Nd:YAG at 1 W and 10 Hz for 40 seconds, and group 3 a coat of self-etching bonding agent, with the lasers given in 3 weekly sessions. Sensitivity to cold was graded at the start, immediately after treatment, and at 1, 3, and 6 months. According to the results, the Nd:YAG laser produced a reduction in tooth sensitivity at 3 and 6 months. Its efficacy at those 2 checks was significantly superior to both the diode laser and the bonding agent.

2018 brought a double-blind randomized controlled trial from a dental institute in India that set a low-level GaAlAs laser against a glutaraldehyde desensitizer, a liquid that seals the dentin, for cervical dentin hypersensitivity. 50 teeth from patients aged 20 to 50 were allocated by coin toss to the desensitizer or to a 905 nm laser at 60 mW and 9 J/cm², pulsed at 4000 Hz and held just off the tooth for 60 seconds. Tooth sensitivity was scored on a self-rated scale immediately after treatment, at 1 week, and at 3 months. Researchers found a significant reduction in pain in both groups at the 3-month check. Although both treatments were effective, the laser was comparatively more effective at the time points studied, according to the conclusion.

Pain scores of 0.0 on every treated tooth after 6 months, whether the tooth had been filled or treated with light, were the outcome of a 2018 single-patient observational study of cervical dentin hypersensitivity. A 31-year-old woman had sensitivity to cold, touch, and sweet or acidic food in the upper right eye tooth and first premolar and the upper left lateral incisor and eye tooth. The right-side teeth had worn notches deeper than 1 mm, so they were given a single session of 808 nm low-power laser at 100 mW and 1.1 J per point for 10 seconds at 2 points each, then filled with composite resin as a barrier. The left-side teeth, with only minimal wear, had 3 laser sessions and no filling. On a 0 to 10 scale, the filled teeth dropped from 9.4 to 0.0 immediately, and the laser-only teeth from 5.4 to 2.0 after the third session, before all reached 0.0 at 6 months.

Immediately after in-office whitening with 35% hydrogen peroxide activated by a hybrid LED-laser device, a patient reported tooth sensitivity on a self-rated scale, in a 2017 single-patient observational study of laser phototherapy (LPT) as a remedy. A 780 nm laser at 70 mW was applied in contact for 10 seconds, 1 J per point, at the middle of the cheek-side surface of each affected tooth. Pain was substantially lower straight after the light, according to the report. At 24 hours the sensitivity had rebounded, so a second session was given, and at 48 hours the patient reported no tooth sensitivity at all. The authors suggested that low-power infrared laser should be considered as an auxiliary method for reducing sensitivity after bleaching.

5% potassium nitrate on its own, an 810 nm low-level laser, and the 2 together were compared across 3 groups in a 2017 randomized controlled trial at a dental college in India for dentin hypersensitivity. 45 patients whose sensitivity scored 2 or more on a self-rated scale were divided among the 3 arms, with group A receiving the nitrate alone. The laser ran at 500 mW for 30 to 60 seconds, held 2 to 6 mm from the tooth, over 3 sessions in 3 weeks. The trial found a greater reduction in tooth sensitivity at 3 weeks in groups B and C, the 2 arms that included the laser, than in group A. Group C, which combined the 2 treatments, gave the better results at the earlier check.

This 2017 split-mouth randomized controlled trial at a dental school in Spain tested photobiomodulation (PBM) for dentin hypersensitivity caused by scaling and root planing, a deep cleaning of the roots used to treat gum disease. 30 patients with 120 sensitive teeth had 2 teeth on 1 side treated with a 660 nm laser and 2 teeth on the other side treated with the laser switched off. Each laser tooth received 200 mW in continuous mode over a 1.15 cm² area, 173 mW/cm² for 60 seconds, 12 J, and 10.4 J/cm². Age, sex, smoking, plaque, gum recession, probing depth, and sensitivity to touch and to cold on a self-rated scale were recorded before treatment, 2 minutes after it, and at 2 weeks, 1 month, and 2 months. A significant difference appeared in favor of the laser teeth, and PBM seemed to reduce tooth sensitivity without harming the pulp.

A 2017 randomized controlled trial at a dental school in Brazil followed 9 treatment protocols for dentin hypersensitivity over 12 and 18 months. 117 sensitive lesions in 32 patients were divided into 9 groups of 13, covering a glutaraldehyde desensitizer, a low-power laser at 2 doses, a high-power laser, and combinations of these. The low-power laser was an 810 nm diode, at 30 mW and 10 J/cm² for the low dose and 100 mW and 40 J/cm² for the high dose, applied at 3 points on the cheek side of the tooth and 1 at the root tip. According to the row, the light treatment was rated effective for tooth sensitivity, but the abstract in the record stops before the results, and no figures can be given here.

1 group received a red 660 nm laser at 200 mW and 12 J/cm² for 15 seconds, a second an infrared 810 nm laser at the same settings, and a third the same procedure with no light, all after in-office whitening with 40% hydrogen peroxide. The setting was a 2016 randomized controlled trial at a dental school in Iran, and all 66 patients, average ages 28.4 to 32.6 and mostly women, completed it. Tooth sensitivity was scored on a self-rated scale at 1, 24, and 48 hours after whitening, and tooth shade 30 days later. The trial found no difference between the groups at 1 hour, a significantly lower pain level with the infrared laser than with the red laser or placebo at 24 hours, and at 48 hours both lasers alike and both significantly below placebo. Whitening was equally effective in all 3 groups, and the infrared laser was recommended as a way to reduce sensitivity after in-office bleaching.

Researchers at a dental faculty in Bosnia and Herzegovina treated 82 sensitive teeth in 18 patients with a 980 nm diode laser over 3 visits in a 2016 clinical trial. The laser was applied at 2 W for 60 seconds, held 2 mm from the tooth, at visits spaced a week apart, with the number of visits depending on how sensitive each tooth was at the start. Sensitivity was scored on a self-rated scale before treatment and after each visit, and scores appeared to fall significantly after the first application, again at 7 days after the second, and again at 14 days after the third. Even teeth that started with very high scores responded to a probe less by the third visit, and the authors described the treatment as extremely safe and effective within the scope of their study.

Researchers at a dental school in Iran asked whether a low-level laser applied just before a composite filling reduces the tooth sensitivity that can follow, in a 2015 randomized controlled trial of class V cavities, the notch-shaped cavities at the gum line. 31 patients each had 2 such cavities, 62 in all, randomly assigned to laser or placebo, and after each cavity was prepared, the laser teeth received 630 nm red light at 28 mW for 60 seconds on the inner wall. The placebo teeth had the same procedure with the laser simulated, and both were then bonded and filled. Sensitivity to cold was scored on a self-rated scale before treatment and on days 1, 14, and 30. Pain after the fillings was significantly lower with the laser, that both groups improved over the month, and that the improvement from the start was significantly greater in the laser group at every check.

Whether a toothbrush that emits low-level laser light reduces dentin hypersensitivity was the question of a 2015 pilot randomized controlled trial at a university in Iran. 40 patients with the condition were randomly given a laser toothbrush, emitting 650 nm light at 5 mW, or a standard Sensodyne toothbrush, and asked to brush for 5 minutes over a 60-day period. Tooth sensitivity was scored on a self-rated scale using an ice spray before treatment, immediately after, and at 1 and 2 months. Both brushes improved sensitivity significantly at every interval. The authors concluded that the laser toothbrush reduced dentin hypersensitivity more than the ordinary brush, with the difference reaching significance at 1 and 2 months but not immediately after treatment.

Across 156 sensitive teeth in 21 patients, split 5 ways within each mouth, a 2015 randomized controlled trial in Turkey tested a low-level laser and an 8% arginine-calcium carbonate desensitizing paste, alone and in either order. Laser teeth received 685 nm light at 25 mW, pulsed at 9 Hz, for 100 seconds over 1 cm², a dose of 2 J/cm², from a probe held 2 mm away. Pain to a puff of air was scored on a self-rated scale over 90 days, and the trial found that all 4 treated groups fell significantly and stayed down, while the untreated teeth stayed high. At day 90, the reductions were 72% for laser, 65.4% for paste, 54.6% for laser then paste, and 69.6% for paste then laser, against a 7.8% rise in the control teeth, so combining the 2 added nothing.

A pain score of 0 within 15 minutes of a single 60-second application, and still 0 a week later, was the result for the longer of 2 laser doses in a 2014 clinical trial at a dental hospital in Sudan of cervical dentine hypersensitivity. 5 patients with at least 2 sensitive teeth each, 14 teeth in all, had an 810 nm diode laser applied without contact at the neck of the tooth, half the teeth for 30 seconds and half for 60 seconds. Sensitivity was scored on a self-rated scale before treatment, 15 minutes after the first application, and 7 days later. The 30-second teeth showed a significant fall in pain at 15 minutes and no pain at all by 1 week, according to the results. The 810 nm laser was judged effective for reducing tooth sensitivity at either dose.

2014 brought a double-blinded split-mouth randomized controlled trial from a dental college in India on whether a 660 nm laser reduces the dentinal hypersensitivity and pain that follow periodontal flap surgery, in which the gum is lifted to clean the roots beneath. 30 patients had the surgery at 60 sites, 1 on each side chosen at random for laser and the other as placebo. The laser site was swept with 660 nm light at 25 mW and 4.5 J for 3 minutes on each of the 3 days after surgery, and the placebo site was swept in the same way with the laser off. Pain and sensitivity were scored on a self-rated scale and a verbal scale on days 1, 3, 5, and 7. According to the results, both tooth sensitivity and pain were significantly lower at the laser site than at the control site by day 7.

Pain scores dropped from 5.8 to 2.3 with a laser-emitting toothbrush, compared with 6.4 to 5.5 with an LED toothbrush, in a 2014 double-blind randomized controlled trial at a university hospital in Korea. 96 people with sensitive teeth but no decay or cracks were randomly given either the test brush, which emitted 635 nm laser light at 6 mW, or a control brush with a 635 nm LED at 12.9 microwatts, and used it for 4 weeks. Sensitivity to a blast of air from 3 mm away was scored on a 0 to 10 scale at screening and after 2 and 4 weeks. Discomfort tended to fall with both brushes, with the significantly larger drop in the laser group, and there were no significant adverse events or side effects.

Researchers in India compared a 940 nm diode laser with 0.4% stannous fluoride gel and 5% potassium nitrate gel for dentin hypersensitivity in a 2013 randomized controlled trial at a dental college. 54 patients aged 25 to 45, each with 2 neighboring teeth sensitive to a blast of air, were divided into 3 groups of 18 and assessed at the start, weekly for 2 weeks, and at 1, 3, and 6 months. Researchers found that all 3 groups had lower sensitivity scores at 6 months than at the start, with the largest fall in the laser group at every interval. The drop between the start and week 1 was statistically significant across the groups and greatest with the laser. The 940 nm laser was judged both effective and quicker to relieve tooth sensitivity than either gel.

According to a 2013 double-masked non-inferiority randomized controlled trial at a university in Brazil, cyanoacrylate, a medical tissue glue, relieved dentin hypersensitivity (the painful tooth sensitivity to cold, sweet food, or brushing that comes from exposed dentin) as well as a low-intensity laser did. 434 sensitive teeth from 62 patients were treated: 216 with a 795 nm laser at 120 mW and 2.88 J/cm² for 8 seconds, and 218 with the glue. Pain from an air jet and a cold spray was scored on a numeric scale at the start and at 24 hours and at 30, 90, and 180 days. Both groups showed significant reductions in tooth sensitivity, with no significant difference between them at any point up to 6 months, according to the report. The glue's effect at 24 hours held for 90 days against the air jet and 30 days against the cold spray, and the authors called it an accessible, low-cost, and safe option.

Patients under long-term gum care, 48 of them with 244 sensitive teeth and at least 4 affected teeth each in different quarters of the mouth, were the subjects of a 2011 randomized controlled trial at a university in Turkey. Their teeth were randomly assigned to a GaAlAs laser, a placebo laser, sodium fluoride varnish, or a placebo varnish of saline, with the laser at 810 nm, 500 mW, and 8.5 J/cm² for 60 seconds held 2 mm from the neck of the tooth. Dentin hypersensitivity was scored on a self-rated scale immediately after treatment and at 1 week and 1, 3, and 6 months. Both laser and varnish appeared to lower tooth sensitivity significantly at once, and both stayed below the starting scores and the placebo scores throughout, while the placebo treatments changed nothing. In the varnish group, however, scores rose again significantly at 3 and 6 months compared with 1 week and 1 month, so the laser was judged the more lasting as well as the more comfortable and faster procedure.

Randomizing 174 sensitive teeth in 51 patients among a GaAlAs diode laser, an erbium laser, and no treatment, all 3 within each mouth, a 2011 double-blind randomized controlled trial in Turkey compared the 2 lasers for dentin hypersensitivity. The diode teeth received 810 nm light at 8.5 J/cm² for 60 seconds. The erbium teeth received the 2780 nm laser in its hard-tissue setting at 0.25 W and 20 pulses per second for 30 seconds, without water spray, from a probe held off the tooth. Sensitivity was scored on a self-rated scale, and both lasers appeared to reduce it immediately after the single application and to keep it lower through every follow-up compared with the untreated teeth and the starting scores. No significant difference between the 2 lasers was found at any check.

In 2011, a randomized controlled trial at a university in Turkey compared low-level laser therapy with a glutaraldehyde desensitizer, a liquid that seals the dentin, for cervical dentin hypersensitivity. 64 teeth in 16 patients were treated with the desensitizer, a 655 nm diode laser at 25 mW and 4 J/cm² in contact for 2.67 minutes, distilled water, or a placebo laser. Sensitivity was scored on a self-rated scale before treatment and at 24 hours and 7 days. The authors concluded that both the desensitizer and the laser lowered dentin hypersensitivity significantly within 7 days, that the 2 placebo groups scored significantly higher, and that laser and desensitizer did not differ from each other. Neither treatment irritated the pulp or the gums, caused pain, or stained the teeth over the week of follow-up.

86.6% of laser patients against 26.6% of fluoride patients were free of pain after the third visit in a 2010 clinical trial at a dental faculty in North Macedonia. The condition was dentinal hypersensitivity following scaling and root planing, the deep cleaning of the roots used to treat gum disease. 15 patients had a low-energy diode laser at 630 to 670 nm, 15 mW, and 100 mW/cm² applied for 20 seconds to each sensitive site, and 15 had a protective fluoride varnish. All were treated at the first visit and again on days 2 and 4, and rated their pain as strong, medium, medium low, low, or none. After the second visit, 26.66% of the laser group already reported no tooth sensitivity at all, while nobody in the fluoride group did, so low-energy laser appeared a successful option for sensitivity after root cleaning.

13 adults, 7 women and 6 men aged 16 to 48, with 52 teeth sensitive where the gums had receded, felt significantly less tooth sensitivity when a diode laser was added to desensitizing toothpaste in a 2010 randomized controlled trial at a university in Turkey. The teeth, all with dentin hypersensitivity, were split equally between toothpaste alone and toothpaste plus laser. The laser teeth received 808 nm light at 100 mW and 2 J/cm² for 25 seconds, held 2 mm from the surface and swept across the exposed root, in 3 sessions. Sensitivity to a puff of air was scored on a self-rated scale at each session. The trial found a significant reduction at every measurement in the laser group and a higher degree of desensitization than with toothpaste alone, both immediately and later, so the combination was judged effective within the limits of a small study.

5 treatments: 2 dentin sealants, an oxalate gel, fluoride, and a low-intensity laser were compared over 6 months in a 2009 randomized controlled trial at a university in Brazil. The condition was cervical dentin hypersensitivity, the tooth sensitivity felt at worn notches near the gum line. 101 teeth with such notches were assigned 20 to a group, with the laser group treated at 660 nm, 3.8 J/cm², and 15 mW in contact for 10 seconds. Sensitivity to a jet of cold air was scored on a self-rated scale before treatment, immediately after it, and at 1 week and 1, 3, and 6 months. The 2 sealants appeared to act immediately, the gel and the fluoride from the first and third month, and the laser brought sensitivity down gradually, so that after 6 months every treatment scored lower than at the start.

Within 15 minutes of a single 810 nm diode laser application, tooth sensitivity to a puff of air had fallen 36.9%, 3 times the 0.23-point change in the control group, in a 2009 randomized controlled trial at a dental clinic in Spain. The trial enrolled 45 patients under ongoing gum care with dentin hypersensitivity scored 2 or more on a verbal scale. 15 received the laser at 1.5 to 2.5 mW for 60 seconds plus a placebo gel, 15 received a placebo laser plus 10% potassium nitrate gel, and 15 received a placebo laser and placebo gel. A blinded examiner scored them at 15 and 30 minutes and on days 2, 4, 7, 14, 30, and 60. The trial found the gap widened by day 14, with a 71.7% reduction with laser against 36.3% with the gel and 28.1% with placebo, and held to day 60 at 65.7%, 30.4% and 25.8%, with both laser and gel judged effective and the laser significantly faster.

3 J/cm² for 1 group of teeth and 5 J/cm² for the other, the lowest and highest energies the maker of the laser recommends, were the 2 doses tested in a 2003 clinical trial at a dental school in Brazil. The condition was dentin hypersensitivity in 25 patients with 106 sensitive teeth between them, 65% of which were premolars. A GaAlAs laser held 3 mm from the tooth was applied for up to 6 sessions, 72 hours apart. Sensitivity was assessed before treatment, after each session, and at 15 and 60 days after the last session. The treatment appeared to work in 86.53% of the teeth at the lower dose and 88.88% at the higher dose, with sensitivity at 60 days significantly below the starting level in both groups and no significant difference between the doses.

12 patients with at least 2 sensitive teeth each, 60 teeth in all, took part in a 2003 clinical trial at a dental school in Brazil of low-level laser therapy against fluoride varnish. The condition was cervical dentin hypersensitivity, the tooth sensitivity felt where the root is exposed at the gum line, and each patient's response to cold before treatment served as the control. A 660 nm GaAlAs laser at 15 mW and 4 J/cm² was applied in contact for 10 seconds, and the varnish was painted on the exposed necks of the teeth, with sensitivity graded immediately after the first application and at 15 and 30 days. According to the trial, no statistically significant difference emerged between varnish and laser, and the laser's own improvement reached significance only between the start and day 30. Both treatments may ease cervical tooth sensitivity, and the laser gave the better results on the most sensitive teeth.

67% less sensitivity to cold and 65% less to touch after 8 weeks of low-level laser therapy, against 17% and 21% with placebo, were the results of a 1994 double-blind randomized controlled trial at a pain clinic in Australia. The trial treated dentin hypersensitivity in 71 patients: 28 in the placebo group and 22 and 21 in the groups tested for touch and for cold. An 830 nm GaAlAs laser at 30 mW and 1.8 J was applied for 1 minute to both the root tip and the neck of each tooth, then again at 1, 2, and 8 weeks. Sensitivity was rated at every visit, and the gap between laser and placebo appeared from the first week and widened at the second and eighth. There were no reported adverse reactions or instances of mouth irritation.

A helium-neon laser on its own and the same laser followed by an Nd:YAG laser were compared on 2 sites per patient in a 1993 double-blind randomized controlled trial at a dental faculty in Canada of tooth sensitivity from exposed dentin, known as dentin hypersensitivity. 19 patients were followed for 3 months. The Nd:YAG delivered 30 to 100 mJ per pulse at 10 pulses per second in bursts of 10 to 40 seconds, under 2 minutes in all, and without local anesthetic, while the 632.8 nm helium-neon beam served as the low-power light. Sensitivity was tested with a sharp probe and a blast of cold air, and tooth vitality with a mild electric current. The trial found that discomfort fell immediately and stayed lower for 3 months by 63% to cold air and 61% to touch with helium-neon alone, and by 58% and 61% with Nd:YAG added, with every tooth still vital and no adverse reactions.

A 4-way split-mouth design, with each quarter of the mouth given a different combination, underpinned a 2019 double-blind randomized controlled trial at a federal university in Brazil of low-level laser therapy (LLLT) and 5% potassium nitrate against tooth sensitivity after whitening with 35% hydrogen peroxide. 50 volunteers had a placebo gel with a mock laser, placebo gel with the laser, nitrate with a mock laser, or nitrate with the laser, the light delivered at 808 nm, 60 J/cm², and 1.7 J for 16 seconds in contact over 3 weekly sessions. Sensitivity was highest on days 1, 8, and 15, the whitening days, in every group. The control quarter stayed sensitive for up to 3 days after each session, while the laser, nitrate, and combined quarters were sensitive only on the whitening days themselves. The 3 treated quarters differed significantly from the control but not from each other.

3 of 280 articles found in searches up to October 2016 met the criteria of a 2018 systematic review from a dental school in Brazil on photobiomodulation (PBM) as a way of controlling pain from dentin hypersensitivity. 241 articles were excluded based on title and abstract, and 36 of the remaining 39 failed at least 1 exclusion criterion when read in full. The review found that PBM may not cause adverse effects for tooth sensitivity provided the treatment settings are properly controlled. Even so, the reviewers concluded that more consistent studies are needed before the therapeutic benefit of PBM can be observed properly. The record provides no pooled result, since only 3 papers remained to compare.

Adults aged 25 to 45 with exposed tooth necks were the patients in a 2004 clinical trial at a university in Brazil that compared a 660 nm red laser with an 830 nm infrared laser. The condition was cervical dentin hypersensitivity, the tooth sensitivity felt where the root shows at the gum line. 20 patients with 40 sensitive teeth were treated in 4 sessions, each tooth assigned to 1 of the 2 lasers, at 4 J/cm² and about 35 mW for 114 seconds in contact with the tooth. Sensitivity to cold was scored on a 0 to 10 scale before each session, at 15 and 30 minutes after the light, and at 15, 30, and 60 days after the course. Researchers found that significant relief occurred only in patients aged 25 to 35, and that the 660 nm laser worked better than the 830 nm laser, with the clearest advantage at the 15- and 30-minute checks.

No statistical difference between any of 5 groups at any time was the outcome of a 2017 placebo-blind randomized controlled trial at a university in Brazil of photobiomodulation for preventing tooth sensitivity after in-office bleaching. 50 patients were divided 10 to a group: no treatment, placebo, laser before bleaching, laser after bleaching, and laser both before and after. The light was 780 nm at 40 mW, 10 J/cm², and 0.4 J, applied in contact for 10 seconds at 2 points on each tooth, 1 in the middle of the crown and 1 over the root tip. According to the results, the laser settings tested did not prevent sensitivity after bleaching. The authors called for further studies with other settings and other ways of measuring sensitivity.

Comparing a 780 nm infrared laser, a 2% sodium fluoride gel, and a placebo gel across 117 sensitive teeth, a 2013 clinical trial in southern Brazil followed dentin hypersensitivity, the tooth sensitivity felt at the exposed necks of the teeth, for 90 days. The teeth from 13 patients were split: 54 to the laser at 20 mW and 5 J/cm² for 10 seconds, 31 to the fluoride gel, and 32 to the placebo. Sensitivity to a puff of air was scored on a self-rated scale and by timing how long the patient could bear the air, at 5 minutes and at 7, 15, 30, and 90 days. No significant differences appeared among the laser, the fluoride gel, and the placebo at any check, the researchers reported. Every group, placebo included, showed less tooth sensitivity across the 90 days, so the trial could not credit either active treatment.

No significant difference among laser, potassium oxalate gel, and a placebo gel, either immediately or at 3 months, was the outcome of a 2009 double-blind randomized controlled trial at a university in Brazil of dentin hypersensitivity. 164 teeth from 30 patients were randomized to a 660 nm GaAlAs laser, to 3% oxalate gel, or to placebo gel, each given once a week for 4 weeks. The laser ran at 30 mW and 4 J/cm² in contact for 2 minutes over the root tip and neck of the tooth. Sensitivity to a blast of air and to touch was scored on a self-rated scale at the start, straight after the fourth session and 3 months later. Every group, placebo included, showed a statistically significant fall in tooth sensitivity at both checks, the researchers reported, adding that longer follow-up might be needed to separate active treatments from placebo.