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Revista Dor

Print version ISSN 1806-0013

Rev. dor vol.14 no.2 São Paulo Apr./June 2013 



Analgesia during orthodontic treatment with low intensity laser: systematic review*



Kevan Guilherme Nóbrega BarbosaI; Thaíse Pereira Dantas SampaioI; Patrícia Ravena Meneses RebouçasII; Maria Helena Chaves de Vasconcelos CatãoIII; Daliana Queiroga de Castro GomesIV; Jozinete Vieira PereiraIV

IMaster Students in Dental Clinic, State University of Paraíba; Graduate in Dentistry, State University of Paraíba. Campina Grande, PB, Brazil
IIMaster Student in Dental Clinic, State University of Paraíba; Specialization Student in Orthodontics, Center of Dental Studies and Improvements. Campina Grande, PB, Brazil
IIIDoctor in Dentistry, Federal University of Bahia; Graduation and Post-Graduation Professor, State University of Paraíba. Campina Grande, PB, Brazil
IVDoctor in Stomatology, State University of Paraíba/Federal University of Bahia; Graduation and Post-Graduation Professor, State University of Paraíba. Campina Grande, PB, Brazil





BACKGROUND AND OBJECTIVES: Pain is a typical symptom during early orthodontic treatment. This study aimed at reviewing the literature on the use of low intensity laser to relieve pain during orthodontic treatment.
CONTENTS: Titles, summaries and articles were searched in the following databases: Pubmed/Medline, Cochrane Library, LILACS and Scielo. Three researchers have independently searched using defined inclusion and exclusion criteria. Eight clinical trials were included and six have observed significant pain relief after therapeutic laser.

CONCLUSION: There are scientific evidences that low intensity laser decreases pain symptoms during dental movements after the placement of orthodontic elastics and after orthodontic adjustments. Its use by dentists is a feasible alternative for inducing less adverse effects as compared to anti-inflammatory analgesics, being indicated for allergic patients, children and patients with systemic impairment. However, there is the need for further scientific investigations using well-defined protocols.

Keywords: Analgesia, Laser, Laser therapy, Low intensity laser, Orthodontics, Pain.




Pain is a typical symptom during early dental treatment, leading to decreased acceptance and noncompliance with next therapeutic stages, and may even determine treatment interruption1. In orthodontics, pain is primarily relieved with non-steroid anti-inflammatory drugs (NSAIDs)2. However, it has to be stressed that NSAIDs should be avoided during orthodontic treatment since they change orthodontic movement mechanism, increasing treatment time3. In addition, some patients are allergic and cannot use such analgesic drug4.

An alternative to analgesic drugs is low intensity laser therapy, used by almost all dental specialties to induce analgesia5. A recent review study has compared different analgesic modalities (drugs and low intensity laser therapy) for orthodontic treatment and has shown that, notwithstanding the broad use of drugs, they may have adverse effects on treatment; authors have also concluded that low intensity laser therapy is a relatively safe alternative needing further attention of the scientific community4. Recent studies have investigated the analgesic potential of Gallium-Aluminum-Arsenide (AsGaAl) laser under different protocols, during orthodontic treatment, and have shown promising results2,6-8. Alternatives such as acupuncture and hypnosis have been indicated for some cases as pain therapy, being effective in some situations9. In orthodontics, however, these alternative therapies have not yet been introduced.

This study aimed at reviewing the use and efficacy of low intensity laser therapy to decrease pain during orthodontic treatment. For such, a systematic review of scientific evidences to date was carried out for the proposed subject.



This review has followed a systematized methodology for querying scientific articles on the proposed subject, as follows:

Pubmed/Medline, Cochrane Library (Cochrane Registry of Controlled Trials), LILACS and Scielo databases were queried. Three investigators have independently read titles and abstracts. Keywords used were extracted from two electronic dictionaries - Health Sciences Keywords dictionary (DeCC) for the Portuguese language and Medical Subject Headings (MeSH) for the English language. The following keywords were included for Portuguese: "dor"; "lasers"; "ortodontia"; "terapia a laser"; "terapia a laser de baixa intensidade". For English, the respective translations of the keywords were included: "pain"; "lasers"; "orthodontics"; "laser therapy"; "laser therapy, low-level". Boolean operator for each term was "and". Chart 1 shows how keywords were entered to databases.



Initial selection was by reading titles and abstracts found by the query, observing the relevance of the proposed subject. Only clinical trials where low intensity laser was used to promote analgesia during orthodontic treatment were included. Languages were Portuguese and English. Experimental studies involving animals and narrative reviews were excluded. Query period ended in October 12, 2012. Figure 1 shows articles inclusion and exclusion criteria.



Data were analyzed as from the development of a questionnaire to collect scientific articles information and then they were displayed in tables for easy visualization. After reading the articles, a comparison was made according to primary variables: significant pain decrease, pain measurement technique, type of method used, ways to evaluate pain and statistical tests used by studies. Secondary variables were: sample size of the test group, type of laser, laser wavelength in nanometers (nm), energy density in Joules by square centimeter (J/cm2) and exposure time per point.



Eight clinical trials were included after selection criteria, being all original scientific articles published from 1995 to 2012 in Orthodontics and Laser Therapy journals. Six out of eight included trials addressed the randomization process. Laser for analgesic purposes was primarily used during orthodontic tooth movement or the placement of orthodontic elastic bands. Placebo and double-blindness were used by most studies. Table 1 shows the studies included in this review.

Laser physical features have varied, but there has been predominance of AsGaAl laser with wavelength above 800 nm, and this range has provided the best analgesic effects. Most frequent dosimetry was in the range of 4-8 J/cm2. Table 2 shows the specificities of lasers.

Pain was measured by scales, preferably the visual analog scale (VAS). Statistical analysis to test significant differences between groups used non parametric tests. Pain decrease was perceived in seven out of eight studies, with best results with Gallium-Aluminum-Arsenide laser. Table 3 shows the methodology to measure and evaluate pain, in addition to results found.



All articles included in this review have investigated laser analgesic action during some orthodontic treatment stage, be it placement of elastic separators10-12, in the adaptation of fixed appliances1,2,7 or orthodontic tooth movement during adjustments6,8. These are recent studies published by relevant Orthodontics and Laser Therapy journals. All eight included studies had placebo group, however only two had control group. Six studies have shown pain decrease with the use of low intensity laser, however among controlled studies one was positive and one was negative for pain decrease. In one trial where such decrease was not observed this might have been caused by the low energy density used, between 0.45 and 1.8 J/cm2, which has equated both groups (laser and placebo). This study was one of the first findings on the use of laser to decrease pain after orthodontic adjustment.

Low-intensity laser for orthodontics has been favorable due to analgesic and anti-inflammatory actions and also for acting on biostimulating processes of tissue repair5. In addition, they induced above-mentioned actions in wavelengths between 632 and 780 nm, thus being applied to tissues without producing mutations and carcinogenesis13.

As to laser particularities, there has been a trend to the use of active AsGaAl medium in wavelengths slightly above 800 nm. Used between 800 and 830 nm, AsGaAl laser has shown the best analgesic effects. This active medium is a semiconductor diode with favorable features for a photochemical action of tissue analgesia, in addition to anti-inflammatory action and tissue biostimulation14,15.

One study has used gaseous carbon dioxide (CO2) laser, although without specifying wavelength. Although not being always predictable, pain decrease associated to CO2 laser is frequent16. A previous study17 has suggested that CO2 laser irradiation decreases early responses to nociceptive stimuli during tooth movement and does not induce periodontal adverse effects.

From included clinical trials, six have mentioned randomization during allocation of group/experimental region and control. Randomization is needed to obtain an equivalent distribution of variables in two groups, thus generating a balance18. Only two studies have not reported the randomization method8,11.

In addition, blindness was another factor observed in included studies, where patients did not know whether they were receiving treatment or placebo. The fact of patients knowing whether they are receiving some therapy or not may psychologically influence them in a positive or negative way, being estimated that the placebo effect induces sensation of relief in 40% of patients who believe are receiving some treatment9. However, due to natural pain evolution, which tends to decrease with the adaptation of patients to treatment, a control group without exposure to laser or placebo should be considered important and was observed in just two studies. One of them12, where no pain decrease was observed, was a preliminary study carried out with a small number of patients, so its conclusions should be carefully analyzed.

A control group without any type of intervention is a good strategy to perceive real pain experienced by patients, since the possibility of a placebo effect is nonexistent or decreased.

Dosimetry, which is the ratio between energy transmitted by a laser emitter and the light beam irradiation surface15, has shown significant differences among studies. This broad variation of application protocols is possibly due to the attempt to study different ways of using laser during orthodontic treatment. In addition, therapeutic purposes among studies were different. Clinically, a dosimetry with analgesic purposes close to 4 J/cm2 has been used, although the application protocol is dependent on patients' response13. With regard to tissue exposure time, there has been predominance of 15 to 30 seconds. Exposure time of current equipment is directly calculated. The dentist programs the device with the desired energy density and wait for the indication of the application time15.

Our study has observed that included clinical trials have followed a laser punctual application methodology, using the visual analog scale to measure pain. This scale has already been validated to evaluate pain in experimental studies19; however pain perception subjectivity among patients may involve some issues that limit its accuracy2.

With regard to statistical analyses, the option for non parametric tests in seven studies suggests that pain perception has a non normal distribution among patients. Only one study has used parametric t test. It has to be considered that the use of non parametric tests, although possible, has limitations as compared to equivalent parametric tests for having less statistical power20.

Studies limitations may be observed in test group sample size, which has varied from 12 to 60 individuals. Sample size for clinical trials is critically important to determine inferences, with difficulties to analyze subgroups when samples are below 30 individuals21. Only one study in this review has detailed the procedure to determine sample size6. Another limitation was the fact that six out of eight studies had no control group in addition to placebo, with possibility of some patients experiencing the placebo effect.

Low intensity laser therapy, which appears as an alternative to analgesics for patients under orthodontic treatment has shown good analgesic effects, being indicated for its beneficial biological effects and for having less side effects as compared to drugs. However, for being a new subject, there are few scientific articles, especially randomized and adequately controlled clinical trials, to give strong scientific evidences about new therapies.



There are scientific evidences that low-intensity laser decreases pain after orthodontic elastic bands placement and after orthodontic adjustments during tooth movement. Best results were found with AsGaAl laser with wavelength between 800 and 830 nm. Low-intensity laser for orthodontics suggests a promising future for dentists since this is an excellent alternative for patients allergic to anti-inflammatory drugs, patients with systemic affections (such as renal affections) and children, due to the non use of pharmacological drugs resulting in fewer side effects. However, there is the need for further scientific investigations using well-defined protocols to allow a comparison among different laser types and application methodologies, as well as to evaluate their efficacy as compared to other available analgesic methods.



1. Turhani D, Scheriau M, Kapral D, et al. Pain relief by single low-level laser irradiation in orthodontic patients undergoing fixed appliance therapy. Am J Orthod Dentofacial Orthop. 2006;130(3):371-7.         [ Links ]

2. Bicakci AA, Kocoglu-Altan B, Toker H, et al. Efficiency of low-level laser therapy in reducing pain induced by orthodontic forces. Photomed Laser Surg. 2012;30(8):460-5.         [ Links ]

3. Chumbley AB, Tuncay OC. The effect of indomethacin (an aspirin-like drug) on the rate of orthodontic tooth movement. Am J Orthod. 1986;89(4):312-4.         [ Links ]

4. Xiaoting L, Yin T, Yangxi C. Interventions for pain during fixed orthodontic appliance therapy. A systematic review. Angle Orthod. 2010;80(5):925-32.         [ Links ]

5. Cavalcanti TM, Almeida-Barros RQ, Catão MHCV, et al. Knowledge of the physical properties and interaction of laser with biological tissue in dentistry. An Bras Dermatol. 2011;86(5):955-60.         [ Links ]

6. Doshi-Mehta G, Bhad-Patil WA. Efficacy of low-intensity laser therapy in reducing treatment time and orthodontic pain: a clinical investigation. Am J Orthod Dentofacial Orthop. 2012;141(3):289-97.         [ Links ]

7. Tortamano A, Lenzi DC, Haddad AC, et al. Low-level laser therapy for pain caused by placement of the first orthodontic archwire: a randomized clinical trial. Am J Orthod Dentofacial Orthop. 2009;136(5):662-7.         [ Links ]

8. Youssef M, Ashkar S, Hamade E, et al. The effect of low-level laser therapy during orthodontic movement: a preliminary study. Lasers Med Sci. 2008;23(1):27-33.         [ Links ]

9. Vale NB. Adjuvant and alternative analgesia. Rev Bras Anestesiol. 2006;56(5):530-55.         [ Links ]

10. Lim HM, Lew KK, Tay DK. A clinical investigation of the efficacy of low level laser therapy in reducing orthodontic postadjustment pain. Am J Orthod Dentofacial Orthop. 1995;108(6):614-22.         [ Links ]

11. Fujiyama K, Deguchi T, Murakami T, et al. Clinical effect of CO2 laser in reducing pain in Orthodontics. Angle Orthod. 2008;8(2):299-303.         [ Links ]

12. Esper MA, Nicolau RA, Arisawa EA. The effect of two phototherapy protocols on pain control in orthodontic procedure - a preliminary clinical study. Lasers Med Sci. 2011;26(5):657-63.         [ Links ]

13. Henriques ACG, Maia AMA, Cimões R, Castro JFL. The lasertherapy in Dentistry: properties, indications and current aspects. Odontol Clín-Cient. 2008;7(3):197-200.         [ Links ]

14. Holmberg F, Muñoz J, Holmberg F, et al. Uso del láser terapéutico en el control del dolor em Ortodoncia. Int J Odontostomat. 2010;4(1):43-6.         [ Links ]

15. Neves LS, Silva CMS, Henriques JFC, et al. Lasers in orthodontics. R Dental Press Orthodon Ortop Facial. 2005;10(5):149-56.         [ Links ]

16. Gama SK, de Araújo TM, Pinheiro AL. Benefits of the use of the CO2 laser in orthodontics. Lasers Med Sci. 2008;23(4):459-65.         [ Links ]

17. Seiryu M, Deguchi T, Fujiyama K, et al. Effects of CO2 laser irradiation of the gingiva during tooth movement. J Dent Res. 2010;89(5):537-42.         [ Links ]

18. Mariano MTS, Januzzi E, Grossmann E. Scientific evidence-based Orthodontics: incorporating science within clinic practice. R Dental Press Orthodon Ortop Facial. 2009;14(3):107-13.         [ Links ]

19. Price DD, McGrath PA, Rafii A, et al. The validation of visual analogue scales as ratio scale measures for chronic and experimental pain. Pain. 1983;17(1):45-56.         [ Links ]

20. Rocha HM. Abordagem metodológica na análise de dados de estudos não paramétricos, com base em respostas em escalas ordinais. GEPROS. 2011;6(3):77-91.         [ Links ]

21. Miot HA. Tamanho da amostra em estudos clínicos experimentais. J Vasc Bras. 2011;10(4):275-8.         [ Links ]


Kevan Guilherme Nóbrega Barbosa, M.D
Rua Paulo Pontes, 260 - Bairro Centenário
58428-210 Campina Grande, PB
Phones: (83) 3333 5629 / (83) 98327223

Submitted in December 20, 2012.
Accepted for publication in April 22, 2013.



* Received from the Dentistry Post-Graduation Program, State University of Paraíba. Campina Grande, PB.

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