UNIVERSIDADE ESTADUAL PAULISTA

“JÚLIO DE MESQUITA FILHO”

Instituto de Ciência e Tecnologia

Campus de São José dos Campos

ORIGINAL ARTICLE DOI: https://doi.org/10.4322/bds.2023.e3940

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

Efeito da terapia LASER de baixa potência versus placa de Michigan CAD/CAM em pacientes com Distúrbios

Temporomandibulares musculares: um ensaio clínico randomizado

Amany Mostafa Saad FARAHAT

, Rami Maher GHALI

, Dina Essam BAHIG



1 - Ain Shams University, Oral and Maxillofacial Prosthodontics Department, Faculty of Dentistry, Cairo, Egypt.

How to cite: Farahat AMS, Ghali RM, Bahig DE. Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with

Temporomandibular Muscle Disorders: a randomized clinical trial. Braz Dent Sci. 2023;26(4):e3940. https://doi.org/10.4322/bds.2023.

e3940

ABSTRACT

Objective: This study aimed to evaluate the efcacy and sustainability of using low level LASER therapy and CAD/

CAM Michigan splint on improving the range of mandibular movements, muscle activity and reducing the pain.

Material and Methods: 56 female patients were randomly divided into two groups. Group A: Patients received

applications of low-level LASER therapy using semiconductor InGaAsp diode LASER type 940 nm with continuous

mode of operation, applied for 180 sec per session for 12 sessions. Group B: Patients received Michigan splint

of 2 mm thickness constructed on their upper teeth, the splint was 3D digitally printed. Electromyography was

used to evaluate muscle activity, visual analogue scale was used to evaluate the pain intensity, ARCUS digma

facebow was used to evaluate range of mandibular movements, and maximum mouth opening was taken using

a millimeter ruler. They were measured before the beginning of the treatment, and at three and six month

follow-up periods. Results: The results revealed that both low-level LASER therapy and Michigan splint reduce

the myofascial pain, improved the range of the mandibular movements, and the muscles activity, but the effect

of the low-level LASER therapy was more profound and sustainable. After 6 months from the beginning of the

treatment, changes in masseter muscle activity (P= 0.001; effect size= 1.757), pain intensity (P= 0.003; effect

size= 3), and range of mandibular movement (P= 0.001, effect size= 1.729) differed signicantly between

the two groups. Conclusions: Low-level LASER therapy had a better and more sustainable effect on reducing

the pain intensity and improving the muscle activity as well as the mandibular movement when compared to

Michigan splint.

KEYWORDS

Electromyogram; Low level LASER therapy; Michigan splint; Muscle disorders; Myofascial pain; Temporomandibular

disorders.

RESUMO

Objetivo: Este estudo teve como objetivo avaliar a ecácia e a durabilidade do uso da terapia LASER de baixa

potência e da placa de Michigan CAD/CAM na melhora da amplitude dos movimentos mandibulares, atividade

muscular e redução da dor. Material e Métodos: 56 pacientes do sexo feminino foram divididos aleatoriamente

em dois grupos. Grupo A: os pacientes receberam aplicações de terapia LASER de baixa potência utilizando

diodo semicondutor InGaAsp LASER tipo 940 nm em modo contínuo de operação, aplicado por 180 segundos

por sessão durante 12 sessões. Grupo B: os pacientes receberam a placa de Michigan com uma espessura de

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

INTRODUCTION

Temporomandibular disorders (TMDs)

are a collective term used to describe a group

of musculoskeletal conditions occurring in the

temporomandibular region. These conditions

are associated with pain in the muscles of

mastication, the temporomandibular joint, or

both, that are usually found during palpation

and function [1].

TMDs are classified into intra-articular

disorders and muscle disorders. Intra-articular

disorders include disc displacement with or

without reduction, arthritis, and arthralgia,

while muscle disorders are further classified

into local myalgia where the pain is conned

into palpated areas of the muscle, myofascial

pain where the pain spreads through the entire

muscle, and myofascial pain with referral where it

spreads also to adjacent structures [2]. Although

myofascial pain is considered the predominant

type of TMDs, it is very difficult for it to be

properly evaluated despite its great impact on

the patients’ quality of life [2-4]. Limitation in

the mandibular movements is also a common

nding in patients suffering from TMDs, it affects

their normal daily functions as their ability to eat

properly and function without pain. Moreover,

the patient will be either complaining of limited

mouth opening that is most probably related to

abnormal muscle activity, or the sudden feeling

that their jaw gets stuck, and this is probably

related to internal disc derangement [4,5].

Other signs and symptoms also related to TMDs

include clicking sounds, headaches, and tension

in the muscles of the back of the neck and the

shoulders [5,6].

Variable treatment modalities have been

introduced by different specialties for the management

of TMDs, including physiotherapy, surgery, and

the use of intraoral appliances [7]. Physiotherapy

includes physical exercises, manual therapy

technique, ultrasound, LASER, and transcutaneous

electrical nerve stimulation (TENS) [8-10]. Surgical

interventions include open joint surgeries and less

invasive procedures as joint lavage and lysis [11].

The use of intraoral appliances includes stabilization

splints (SS), anterior repositioning splint, and bite

planes [12,13].

SS is a full coverage removable intraoral

occlusal splint worn over the maxillary or the

mandibular teeth, to reduce the amount of

tooth contact preventing the tooth wear, while

providing the patient with an ideal occlusal

scheme, free from interference [13,14]. It is very

effective in reducing pain especially in cases of

patients suffering from muscle hyperactivity [14].

SS is a conservative treatment approach for

TMDs, yet the durability of its effect on muscles

activity and pain level is still controversial and

there is lack of strong evidence for its long-term

effect. As a lot of studies have proven that the

effect of the SS lasts only as long as the patient

wears it, and that it is mostly used as a diagnostic

tool to identify the etiology of the TMD [15].

Low-level LASER therapy (LLLT),

biostimulation, or photobiomodulation is a type

2 mm confeccionada sobre a arcada superior, a placa foi impressa digitalmente em 3D. A eletromiograa foi

utilizada para avaliar a atividade muscular, a escala visual analógica foi utilizada para avaliar a intensidade

da dor, o arco facial ARCUS digma foi utilizado para determinar a amplitude dos movimentos mandibulares e

a abertura máxima da boca foi medida com uma régua milimétrica. Todas as medidas foram realizadas antes

do início do tratamento e nos períodos de acompanhamento de três e seis meses. Resultados: Os resultados

revelaram que tanto a terapia LASER de baixa potência como a placa de Michigan reduziram a dor miofascial,

aumentaram a amplitude dos movimentos mandibulares e melhoraram a atividade muscular, mas o efeito da

terapia LASER de baixa potência foi mais profundo e duradouro. Após 6 meses do início do tratamento, as

alterações na atividade do músculo masseter (P= 0. 001; tamanho do efeito= 1,757), intensidade da dor (P=

0,003; tamanho do efeito= 3), e amplitude de movimento mandibular (P= 0,001, tamanho do efeito= 1,729)

diferiram signicativamente entre os dois grupos. Conclusão: A terapia com LASER de baixa potência teve um

efeito melhor e mais duradouro na redução da intensidade da dor e na melhora da atividade muscular, bem

como do movimento mandibular, quando comparada à placa de Michigan.

PALAVRAS-CHAVE

Distúrbios musculares; Distúrbios temporomandibulares; Dor myofascial; Eletromiograma; Placa de Michigan;

Terapia LASER de baixa potência.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

of therapy that has become recently popular in

the management of a wide variety of medical

and dental conditions, such as wound healing,

tissue repair and prevention of further damage

and tissue death, relief of inammation, pain,

and edema in chronic diseases and injuries,

as well as relief of neurological pain [16].

LLLT is non-invasive, painless, and can be

easily administered [17,18]. LLLT reduces

prostaglandins(PGE2), interleukins(IL1), tumor

necrosing factors, plasminogen activator,

histamine and acetylcholine levels, neutrophil

cell influx, hemorrhagic formation, COX-2

expression, cell apoptosis. It also improves

microcirculation [19,20], and inhibits

the transmission at the neuro muscular

junction [21-23], which in turn helps in the

reduction of chronic pain and improves the

muscles’ function.

But would the use LLLT for pain management

and function improvement sustain its effect for

a longer period when compared with the SS or

would it be considered another conservative and

reversible treatment option for myofascial pain

associated with TMDs?

So, we conducted this study to compare the

long-term effect of these two conservative non-

invasive techniques used in the management of

pain related TMDs, and to determine which one

of them would sustain its effect after the end

of the treatment. The null hypothesis was that

there is no difference between the long-term

effect of both techniques on the muscle function

improvement and pain relief.

MATERIALS AND METHODS

Institutional research board (IRB) approval

and trial registration

This study was approved by Ethics

committee of scientic research of Faculty of

Dentistry, Ain Shams university, with approval

code: FDASU-REC IR112207, and registered

at www.clinicaltrials.gov with reference no.

NCT05901701.

Sample size calculation

Sample size calculation was performed using

G*Power version 3.1.9.7 based on the results

of a previous study [24]. A power analysis was

designed to have adequate power to apply a two-

sided statistical test to reject the null hypothesis

that there is no difference between groups. By

adopting an alpha level of (0.05) and a beta of

(0.2), i.e., power = 95% and an effect size (d)

of (1.09) calculated based on the results of a

previous study. The predicted sample size (n) was

(46), i.e., 23 samples per group. For treatment of

TMJ problem and detect for difference between

two modalities.

Recruitment and selection criteria

From the outpatient clinic of oral and

maxillofacial department, Faculty of dentistry,

Ain Shams university, dentulous patients suffering

from the following DC/TMD signs and symptoms of

myofascial pain were selected; pain in the muscles of

mastication (temporalis and masseter) that affects

the jaw movements and get worse with function.

On palpation of the involved muscles, a palpable

painful taut bands were noticed, in association

with referred pain to other areas beyond the point

of palpation but within the bulk of the palpated

muscle, this hyperirritable spots were considered

trigger points and three of them were chosen to

apply the LLLT on it later, other signs and symptoms

manifested as headache, periauricular pain or pain

in the TMJ, teeth wear that appears in the form of

multiple smooth shiny facets, teeth mobility, and

malocclusion. Taking into consideration that any

patient who suffered from one of the following

criteria was excluded; pregnant females, breast

feeders, patients having pacemakers, heart disease,

tumors, general connective tissue disease e.g.,

Rheumatoid arthritis, psychiatric disorders, skeletal

morphology as class II or III, TMJ clicking sounds,

local skin infection over the masseter or temporalis,

symptoms that may be referred to other disorders of

orofacial region (tooth ache, trigeminal neuralgia,

migraine), or patients using medications such as

Muscle relaxant, Steroids, Dopamine precursors

like L dopa and Aminoglycoside.

From the selected patients, fifty-six

participants met the selection criteria and

managed to complete the treatment and follow

up to take part in this clinical trial. The age range

of the selected patients was from 35 to 55 y,

they were suffering from the previous signs and

symptoms from 6 months up to 2 years.

Study design

Blocked randomization technique was used

to divide the patients into two equal groups (28

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

per each) using sealed envelopes, the person who

was in charge for randomization was blinded to

the group allocation of the patients. The outcome

assessors also didn’t know the allocated groups,

and the patients were instructed not to mention

their groups to the assessors. Three operators

were involved in the assessment process, one

for the assessment of the muscle activity using

the EMG, another one for the assessment of the

mandibular movement using ARCUS digma and

the maximum mouth opening using graduated

ruler, and the last one for the assessment of the

pain intensity using VAS. Each outcome was

assessed by the same operator through the entire

process for all the patients. The Consolidated

Standards of Reporting Trials (CONSORT)

specications were applied.

Intervention

In the rst group patients received LLLT,

while in the second group the patients received

2mm thickness maxillary hard occlusal splints

(Michigan splints).

For the LASER group, diode LASER (Epic

10, Biolase, USA) with wavelength 940nm was

used after calibration using a LASER power sensor

and meter. First the skin was cleaned with 70%

alcohol gel, according to the facial template the

trigger points were determined. The deep tissue

hand piece with spacer was locked at the 25

mm notch to deliver the LASER beam with spot

size of 25 mm to the target tissue (Figure 1),

and then the diode LASER machine (940 nm)

was adjusted to the required parameters, pain

therapy mode, with the power output 4W, for 30

seconds, with continuous mode of emission. Total

energy of 120J, power density 1.6 W/cm

, and

effective dose 48 J/Cm

were received by each

trigger point. Three points were chosen on the

temporalis and masseter area. Two of them were

located on the body of the masseter muscle below

the ala tragus line, and one over the insertion of

the temporalis below the hairline . Any synthetic

clothes at the eld where the LASER beam passed

were removed. Both the patient and the operator

wore their protective goggles specic for 940 nm

diode LASER wavelength. The hand piece was

held in intimate contact, and at 90

with the

patient’s skin (Figure 2), the foot control was

pressed to allow the LASER beam to be released.

Each patient received a total of twelve sessions

for six weeks, two sessions per week.

For the splint group, maxillary and mandibular

impressions were done using heavy consistency

polyether impression material (Identium Heavy

– kettenbach, USA.) in a proper sized stock tray,

and then poured immediately using type III dental

stone (Gypsano Lab Dental Stone, Gypsano, UAE.).

The maxillary cast was mounted on the semi-

adjustable articulator (Bio-Art, Dentaltix, Madrid,

Spain) by means of a face bow record and centric

occluding relation record was taken to mount the

lower cast.

On the articulator the incisal post was adjusted

to allow 2 mm vertical separation between the

posterior teeth, a protrusive record was taken

from the patient and used to adjust the protrusive

and lateral condylar guidance on the articulator.

The articulator with the casts mounted on it was

scanned using desktop scanner (Planmeca plan

scan, Texas, USA), and both protrusive and lateral

condylar guidance values were introduced to

the virtual articulator on the software (8 Exocad

software 2.4). Virtual designing of the splint was

done with the following criteria, flat occlusal

Figure 1 - Deep tissue hand piece with a spacer attached at the

25 mm spot size notch.

Figure 2 - LASER beam directed to the trigger point using deep

tissue hand piece.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

surface to achieve contact with only the working

cusps of all the mandibular posterior teeth, and

in the canines’ area it had two occlusal ramps to

create separation of the posterior teeth during

the eccentric mandibular movement, it extended

on the hard palate in the form of horseshoe while

labially and buccally it ended 2mm below the

incisal edge and across the height of the contour of

the posterior teeth. The splint was printed using a

3D printer (Phrozen printer, Phrozen Tech Co. Ltd,

Taiwan) and liquid resin (NextDent Ortho Clear,

NextDent, Soesterberg, Netherlands). The splint

(Figure 3) was checked in the patient mouth for

retention, and proper disocclusion of the posterior

teeth during lateral and protrusive movements

using articulating paper placed at the area of the

canine ramps and asking the patient to protrude

the mandible and move from one side to other

side, till un-interrupted V-shape was produced on

the canine ramps. The patients were instructed to

gradually wear off the splint after 3 months but

told to wear it if their discomfort returns which is

often at times of stress.

Assessment

Before the beginning of the treatment, and

at three and six months after the beginning of the

treatment, changes in muscle activity, mandibular

movement, mouth opening range, and pain

intensity were assessed.

The change in muscle activity was assessed

using EMG (Dantec “keypoint”, Apline Biomed,

Denmark), rst the patient was seated upright with

unsupported head to allow the muscles to relax,

then the patient was instructed to look forward

and perform maximum clenching in centric

occlusion to locate both masseter and temporalis

muscles, each muscle was palpated to identify the

trigger points, three trigger points in the masseter

and temporalis area were selected and marked on

each side. These points were transferred to a clear

celluloid template which is positioned on the face

with the aid of a window cut at the ala of the nose,

to help reposition the template each time during

EMG measuring in the follow up periods and in

the upcoming LASER treatment sessions. The ala

tragus line was also drawn on the template to aid

in the repositioning process.

The EMG ground electrode was positioned

on the forehead and the active electrodes were

positioned on the trigger points, rst the active

electrodes were positioned over the trigger points

of the right masseter temoralis muscle area then

the patient was asked to chew a 1cm cube of

carrot on the right side for 30 seconds, and the

readings were recorded, then the same process

was repeated for the left masseter, right and left

temporalis.

The range of mandibular movements was

assessed using ARCUS digma (ARCUS digma II,

Kavo, Germany), rst the upper face bow was

secured to the upper arch using rubber base

material to the bite fork and the spatial orientation

of the maxillary arch was recorded while the

patient was sitting upright. The para-occlusal

clutch was prepared and attached to the patient’s

mandibular teeth (Figure 4). The patient was asked

to perform the required mandibular movements

which are the protrusive, lateral right and left

border movements, to record maximum range of

motion. The horizontal condylar inclination was

calculated and displayed on the screen.

The maximum mouth opening (MMO) of the

patients was recorded between the incisal edges

of the upper and lower central incisors using a

graduated ruler.

Figure 3 - Intraoral frontal view of Michigan splint.

Figure 4 - ARCUS Digma facebow secured to the patient head to

assess the mandibular movements.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

The visual analogue scale is a widely used

subjective measurement tool for the assessment

of the severity of a certain pain in patients. The

degree of pain intensity was recorded using a 10

cm scale that represents the spectrum from no

pain to the worst pain. In this study the patients

were asked to express the degree of pain they

were experiencing using this scale. This was

done before the beginning of treatment after 3

and 6 months.

After the assessment of the effect of the two

treatment modalities during the three and six

months follow up periods was done, data were

collected.

Data analysis

All the patients involved in both groups

continued the treatment and showed up for the

follow up records, The four outcomes for the two

treatment modalities were statistically analyzed

to evaluate the signicant difference between the

baseline and post operative readings.

The numerical data for the 56 patients

was collected and explored for normality by

checking the distribution using tests of normality

(Kolmogorov-Smirnov and Shapiro-Wilk tests).

All data showed non-normal (non-parametric)

distribution except for MMO data which showed

normal (parametric) distribution.

Parametric data were presented as mean,

standard deviation (SD) values while non-

parametric data were presented as median and

range values. For parametric data, repeated

measures ANOVA test was used to compare

between the groups as well as to study the

changes by time within each group. Bonferroni’s

post-hoc test was used for pair-wise comparisons

when ANOVA test is signicant.

For non-parametric data, Mann-Whitney

U test was used to compare between the two

groups. Friedman’s test was used to study the

changes by time within each group. Dunn’s

test was used for pair-wise comparisons when

Friedman’s test is signicant. The signicance

level was set at P ≤ 0.05. Statistical analysis was

performed with IBM SPSS Statistics for Windows,

Version 23.0. Armonk, NY: IBM Corp.

RESULTS

Regarding the EMG (Table I) and VAS

(Table II) records, pair-wise comparisons between

time periods in each group revealed that, for the

LLLT group there was statistically significant

decrease in the muscles’ activity and pain

intensity in both three and six months readings,

while in the splint group there was statistically

signicant decrease in the muscles’ activity for

both masseter and temporalis muscles and pain

intensity at the three months follow up period

when compared with the baseline data followed

by non-statistically signicant change at the six

months follow up reading.

When the two groups were compared with

each other, there was no statistically signicant

difference in the masseter muscle activity and

pain intensity at the baseline data and at the three

months follow up period, but when compared at

the six months follow up period the splint group

Table I - Descriptive statistics and results of Mann-Whitney U test for comparison between muscle activities (Microvolt) in the two groups and

Friedman’s test for the changes within each group

Muscle Time

LLLT (n = 56 muscles) SPLINT (n = 56 muscles)

P-value

Eﬀect size

(d)

Median (Range) Mean (SD) Median (Range) Mean (SD)

Masseter

Pre-operative 218 (107-553)

172.6 (57.2) 191 (89.7-239)

172.6 (57.2) 0.057 0.844

3 months 139 (81.7-169)

131.1 (30.3) 137.5 (75.1-174)

131 (30.3) 0.977 0.012

6 months 82.7 (56-143)

133.2 (30) 132 (78.6-170)

133.2 (30) 0.001* 1.757

-value <0.001* 0.001*

Eﬀect size (w)

0.924 0.549

Temporalis

Base line 215.5 (124-318)

212.7 (60) 234.5 (154-450)

249.5 (79.3) 0.402 0.347

3 months 148.5 (105-242)

154.6 (38.8) 143 (58.7-210)

144.7 (40.6) 0.840 0.083

6 months 119 (99.3-200)

132.5 (35.2) 137.5 (70.2-289)

145.6 (55.2) 0.544 0.249

-value <0.001* 0.001*

Eﬀect size (w)

0.924 0.632

*Signiﬁcant at P ≤ 0.05. Diﬀerent superscripts in the same column indicate statistically signiﬁcant change by time.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

showed a higher level of muscle activity and pain

intensity which were statistically signicant.

For the temporalis muscle, it was found that

there was no signicant difference in the muscle’s

activities in both groups either in the baseline

data or in both follow up periods.

Regarding the change in the range of the

horizontal mandibular movement (Table III),

pair-wise comparisons between time periods in

each group revealed that, within both groups

there was statistically significant increase in

the horizontal condylar inclination in the three

months readings when compared to the baseline

data, followed by non-statistically significant

change at the six months follow up reading.

When the two groups were compared with

each other, there was no statistically signicant

difference at the baseline data and at the three

months follow up period, but when compared at

the six months follow up period the splint group

showed a lower level of horizontal condylar

inclination which was statistically signicant.

As for the MMO (Table IV), pair-wise

comparisons between time periods in each group

revealed that, within the LLLT group there was

statistically signicant increase in the MMO in

both three and six months readings, while in the

splint group there was statistically signicant

increase in the MMO at the three months follow

up period when compared with the baseline data

Table II - Descriptive statistics and results of Mann-Whitney U test for comparison between pain (VAS) scores in the two groups and

Friedman’s test for the changes within each group

Time

LLLT (n = 28 patients) SPLINT (n = 28 patients)

P-value

Eﬀect size

(d)

Median (Range) Mean (SD) Median (Range) Mean (SD)

Pre-operative 5 (4-8)

5.5 (1.6) 5.5 (4-8)

5.8 (1.5) 0.621 0.28

3 months 2.5 (1-3)

2.3 (0.8) 3 (1-3)

2.5 (0.8) 0.652 0.233

6 months 1 (0-1)

0.7 (0.5) 3.5 (2-5)

3.5 (1) 0.003* 3

-value 0.002* 0.009*

Eﬀect size (w)

1 0.78

*Signiﬁcant at P ≤ 0.05. Diﬀerent superscripts in the same column indicate statistically signiﬁcant change by time. e same column indicate

statistically signiﬁcant change by time.

Table III - Descriptive statistics and results of Mann-Whitney U test for comparison between horizontal condylar inclination (º) in the two

groups and Friedman’s test for the changes within each group

Time

LLLT (n = 56 joints) SPLINT (n = 56 joints)

P-value

Eﬀect size

(d)

Median (Range) Mean (SD) Median (Range) Mean (SD)

Pre-operative 18 (-14.9-24.5)

14.3 (11.5) 12.5 (1.9-23.1)

13.1 (6) 0.225 0.511

3 months 29.4 (2-41.6)

25.8 (11.8) 20.5 (2.7-39)

20.6 (9) 0.069 0.8

6 months 32.8 (11.8-45.7)

31.7 (9.9) 15.7 (2.6-25.4)

15.8 (6.3) 0.001* 1.729

-value <0.001* <0.001*

Eﬀect size (w)

0.924 0.924

*Signiﬁcant at P ≤ 0.05.Diﬀerent superscripts in th.

Table IV - Descriptive statistics and results of repeated measures ANOVA test for comparison between MMO (cm) in the two groups and the

changes within each group

Time

LLLT (n = 28 patients) SPLINT (n = 28 patients)

P-value

Eﬀect size

(Partial Eta

squared)

Mean SD Mean SD

Pre-operative 3.2

0.22 3.32

0.47 0.591 0.03

3 months 3.75

0.21 4.08

0.5 0.165 0.183

6 months 4.15

0.23 3.92

0.5 0.319 0.099

-value <0.001* 0.001*

Eﬀect size (Partial

Eta squared)

0.828 0.805

*Signiﬁcant at P ≤ 0.05. Diﬀerent superscripts in the same column indicate statistically signiﬁcant change by time.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

followed by statistically signicant decrease at the

six months follow up reading but still statistically

significant higher when compared with the

baseline data.

When the two groups were compared with

each other, there was no statistically signicant

difference at the baseline data and at the three

and six months follow up periods.

DISCUSSION

Both LLLT and Michigan occlusal splint are

considered effective conservative non- invasive

techniques in the management of pain related

TMDs, but the main objective of an effective

treatment modality is to be sustainable, so this

study aimed to evaluate whether the effect of both

treatments would be sustainable or not after the

patients stop the treatment.

In this study LLLT caused a significant

difference in the EMG readings, and VAS records

between the baseline data, and the three months

follow up records, and also between the three

and six months follow up records. This may be

attributed to the therapeutic biostimulatory effect

of low level LASER on the cells which improves

the cells functions, increases the production of

ATP [21-23], which in turn increases the activity of

(Na

/Ca

) exchanger protein, that is responsible

for controlling the Ca

level, by removing one

ion from the cell in exchange with 3 Na

ions into the cell, controlling the Ca

level is

important for normal muscle contraction [16].

This occurs in conjunction with the improvement

in the microcirculation and the inhibition in the

transmission at the neuromuscular junction,

leading to muscle relaxation [20-23].

Many studies have proven that the use of

LLLT in treatment of TMDs causes improvement

in both function and pain relief. The study done

by Venezian et al. [25] to evaluate the effect of

diode LASER (780 nm) in the management of

myofascial pain by using the VAS, showed that

there was a reduction in the pain level in both

temporalis and masseter muscles, yet there was

no signicant change in the EMG records before

and after the treatment. Mazzetto et al. [26]

stated that when LLLT was applied to four points

around the lateral pole of the condyles has proven

to be effective in reducing the myofascial pain

and improving the range of the mouth opening.

The insignicant change in the readings of the

temporalis muscle can be attributed to the limited

area available for the admission of laser below

the hair line.

There was signicant improvement in the

horizontal mandibular movement and the range

of MMO, indicating that the use of LLLT with the

suggested protocol had a profound effect on the

involved muscles caused by its anti-inammatory

and pain-relieving effect, and this coincides with

the results of previous studies [26-28].

In the group of patients that received the

Michigan splint, there was an improvement in the

EMG readings, VAS records and horizontal jaw

movement readings at the three months follow

up period when compared to the baseline data,

but on comparing the three months follow up

data with the six months recorded data, there

was no statistically signicant change and this is

properly linked to the discontinuity of using the

splint after the three months records were done.

Many researches have reported that the

use of Michigan occlusal splint has proven its

effectiveness in the relief of muscle pain over

time [27-30], but the exact hypothesis for the

improvement in muscle activity and pain relief

is still controversial. As some studies [30-33]

suggest that the relief of the pain was caused

by the elimination of the occlusal discrepancies

leading to “interference free” occlusion, while

others [31,34] adopted the concept of the

cognitive theory, that the use of the splint change

the oral environment affecting the available space

for the tongue, making the patients aware of

their habit and conscious about the position of

the mandible, also being aware of the presence

of a foreign object intraorally causes alteration in

the peripheral sensory input to central nervous

system (CNS) decreasing the CNS induced

bruxism, but when the patient accommodates

to the splint, they usually show symptoms of

bruxism [35]. Another theory suggested that the

increase in the vertical dimension of rest results

in muscle relaxation [31,36].

Although the use of splints is very effective

in reducing myofascial pain, several studies

reported that it has short term effect. Kuzmanovic

Pficer et al. [37], this meta-analysis study

included thirty three randomized control trials

that compared between the SS with other

treatment modalities, it proved that the SS has

positive short-term effect on the reduction of pain

and improvement of the mandibular movement,

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

but in the long-term follow up there was no

signicant difference between the SS group and

the control group, and this is also supported

by the ndings in this study, as there was no

significant difference between the three and

six months EMG, VAS and horizontal condylar

guidance records for the splint group when the

patient ceases to use the splint after 3 months

from the beginning of the treatment.

CONCLUSION

The null hypothesis was rejected due to the

signicant difference between the two groups as

LLLT had a better and more sustainable effect

on reducing the pain intensity and improving

the muscle activity as well as the mandibular

movement when compared to Michigan splint.

Based on the ndings of this study it has been

showed that the use of LLLT has a more profound

and sustainable effect in the management of

muscle pain and in the improvement of the

mandibular movements in cases with TMDs when

compared to Michigan splint.

Author’s Contributions

AMSF: Conceptualization, Methodology,

Writing – Original Draft Preparation, Writing –

Review & Editing, Resources. RMG: Visualization,

Supervision, Project Administration. DEB: Formal

Analysis, Investigation, Resources, Data Curation,

Writing – Review & Editing.

Conict of Interest

All authors declare that they have no

conicts of interest.

Funding

This research did not receive any specic

grant from funding agencies in the public,

commercial, or not-for-prot sectors.

Regulatory Statement

This study was conducted in accordance with

all the provisions of the local human subjects

oversight committee guidelines and policies of:

Ethics committee of scientic research, Faculty

of Dentistry, Ain Shams university, the approval

code is: FDASU-REC IR112207, and registered

at www.clinicaltrials.gov with reference no.

NCT05901701.

REFERENCES

1. Kalladka M, Young A, Khan J. Myofascial pain in temporomandibular

disorders: updates on etiopathogenesis and management. J

Bodyw Mov Ther. 2021;28:104-13. http://dx.doi.org/10.1016/j.

jbmt.2021.07.015. PMid:34776126.

2. Ferrillo M, Giudice A, Marotta N, Fortunato F, Di Venere D,

Ammendolia A, etal. Pain management and rehabilitation

for central sensitization in temporomandibular disorders: a

comprehensive review. Int J Mol Sci. 2022;23(20):12164. http://

dx.doi.org/10.3390/ijms232012164. PMid:36293017.

3. Miettinen O, Lahti S, Sipilä K. Psychosocial aspects of

temporomandibular disorders and oral health-related quality-

of-life. Acta Odontol Scand. 2012;70(4):331-6. http://dx.doi.org

/10.3109/00016357.2011.654241. PMid:22300221.

4. Fillingim RB, Ohrbach R, Greenspan JD, Knott C, Diatchenko

L, Dubner R, etal. Psychological factors associated with

development of TMD: the OPPERA prospective cohort study.

J Pain. 2013;14(12, Suppl):T75-90. http://dx.doi.org/10.1016/j.

jpain.2013.06.009. PMid:24275225.

5. Pedroni CR, De Oliveira AS, Guaratini MI. Prevalence study

of signs and symptoms of temporomandibular disorders in

university students. J Oral Rehabil. 2003;30(3):283-9. http://

dx.doi.org/10.1046/j.1365-2842.2003.01010.x. PMid:12588501.

6. De Rossi SS, Greenberg MS, Liu F, Steinkeler A.

Temporomandibular disorders: evaluation and management. Med

Clin North Am. 2014;8(6):1353-84. http://dx.doi.org/10.1016/j.

mcna.2014.08.009. PMid:25443680.

7. Maia MLM, Bonjardim LR, Quintans JSS, Ribeiro MAG, Maia LGM,

Conti PCR. Effect of low-level LASER therapy on pain levels

in patients with temporomandibular disorders: a systematic

review.J ApplOral Sci. 2012;20(6):594-602. http://dx.doi.

org/10.1590/S1678-77572012000600002. PMID:23329239.

8. McNeely ML, Armijo Olivo S, Magee DJ. A systematic review

of the effectiveness of physical therapy interventions for

temporomandibular disorders. Phys Ther. 2006;86(5):710-25.

http://dx.doi.org/10.1093/ptj/86.5.710. PMid:16649894.

9. Rodrigues D, Siriani AO, Bérzin F. Effect of conventional TENS

on pain and electromyographic activity of masticatory muscles

in TMD patients. Braz Oral Res. 2004;18(4):290-5. http://dx.doi.

org/10.1590/S1806-83242004000400003. PMid:16089258.

10. Öz S, Gökçen-Röhlig B, Saruhanoglu A, Tuncer EB. Management

of myofascial pain: low-level LASER therapy versus occlusal

splints. J Craniofac Surg. 2010;21(6):1722-8. http://dx.doi.

org/10.1097/SCS.0b013e3181f3c76c. PMid:21119408.

11. Bouloux G, Koslin MG, Ness G, Shafer D. Temporomandibular joint

surgery. J Oral Maxillofac Surg. 2017;75(8S):e195-223. http://

dx.doi.org/10.1016/j.joms.2017.04.027. PMid:28728730.

12. Ebrahim S, Montoya L, Busse JW, Carrasco-Labra A,

Guyatt GH, Medically Unexplained Syndromes Research

Group. The effectiveness of splint therapy in patients with

temporomandibular disorders: a systematic review and meta-

analysis. J Am Dent Assoc. 2012;143(8):847-57. http://dx.doi.

org/10.14219/jada.archive.2012.0289. PMid:22855899.

13. Albagieh H, Alomran I, Binakresh A, Alhatarisha N, Almeteb

M, Khalaf Y, etal. Occlusal splints-types and effectiveness

in temporomandibular disorder management. Saudi Dent J.

2022;35(1):70-9. http://dx.doi.org/10.1016/j.sdentj.2022.12.013.

PMid:36817028.

14. Lukic N, Saxer T, Hou MY, Zumbrunn Wojczyńska A, Gallo LM,

Colombo V. Short‐term effects of NTI‐tss and Michigan splint

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

on nocturnal jaw muscle activity: a pilot study. Clin Exp Dent

Res. 2021;7(3):323-30. http://dx.doi.org/10.1002/cre2.371.

PMid:33369223.

15. Okeson JP. Occlusal appliance therapy: Common Treatment

Considerations of Appliance Therapy. In: Management of

temporomandibular disorders and occlusion, 8th ed. USA:

Elsevier Health Sciences; 2019. p. 385- 409

16. Hamblin MR, Demidova TN. Mechanisms of low level

light therapy. Proc SPIE. 2006;6140:1-12. http://dx.doi.

org/10.1117/12.646294.

17. Bjordal JM, Johnson MI, Lopes-Martins RA, Bogen B, Chow R,

Ljunggren AE. Short-term efficacy of physical interventions in

osteoarthritic knee pain. A systematic review and meta-analysis

of randomised placebo-controlled trials. BMC Musculoskelet

Disord. 2007;8:51. http://dx.doi.org/10.1186/1471-2474-8-51.

PMid:17587446.

18. Bjordal JM, Lopes-Martins RA, Joensen J, Couppe C,

Ljunggren AE, Stergioulas A, Johnson MI.A systematic

review with procedural assessments and meta-analysis of

photobiomodulation in lateral elbow tendinopathy (tennis

elbow). BMC Musculoskelet Disord. 2008;9:75. http://dx.doi.

org/10.1186/1471-2474-9-75. PMid:18510742.

19. Liebert MA, Bjordal JANM, Johnson MI, Iversen V, Lopes-Martins

RAB. Low-level LASER therapy in acute pain: a systematic

review of possible mechanisms of action and clinical effects

in randomized placebo-controlled trials. Photomed Laser Surg.

2006;24(2):158-68. http://dx.doi.org/10.1089/pho.2006.24.158.

PMid:16706694.

20. Bjordal JM, Lopes-Martins RAB, Iversen VV. A randomised,

placebo controlled trial of low level LASER therapy for

activated Achilles tendinitis with microdialysis measurement of

peritendinous prostaglandin E2 concentrations. Br J Sports Med.

2006;40(1):76-80, discussion 76-80. http://dx.doi.org/10.1136/

bjsm.2005.020842. PMid:16371497.

21. Nicolau RA, Martinez MS, Rigau J, Tomas J. Effect of low power

655 nm diode LASER irradiation on the neuromuscular junctions

of the mouse diaphragm. Lasers Surg Med. 2004;34(3):277-84.

http://dx.doi.org/10.1002/lsm.20006. PMid:15022258.

22. De Andrade ALM, Bossini PS, Parizotto NA. Use of low level

LASER therapy to control neuropathic pain: a systematic

review.J Photochem Photobiol B. 2016;164:36-42. http://dx.doi.

org/10.1016/j.jphotobiol.2016.08.025. PMid:27639607.

23. Nicolau RA, Martinez MS, Rigau J, Tomas J. Neurotransmitter

release changes induced by low power 830 nm diode LASER

irradiation on the neuromuscular junctions of the mouse. Lasers

Surg Med. 2004;35(3):236-41. http://dx.doi.org/10.1002/

lsm.20087. PMid:15389739.

24 ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of

Medicine (US). 2000 Feb 29 -. Identiﬁer NCT05901701, Eﬃcacy

of Low Level LASER Therapy in Treating Temporomandibular

Muscle Disorders ( RCT ); 2023 May 20 [cited 2023 June 4];

[about 4 screens]. Available from: http://clinicaltrials.gov/study/

NCT05901701

25. Venezian GC, da Silva MA, Mazzetto RG, Mazzetto MO. Low

level LASER effects on pain to palpation and electromyographic

activity in TMD patients: a double-blind, randomized, placebo-

controlled study. Cranio. 2010;28(2):84-91. http://dx.doi.

org/10.1179/crn.2010.012. PMid:20491229.

26. Mazzetto MO, Hotta TH, Pizzo RC. Measurements of jaw

movements and TMJ pain intensity in patients treated with

GaAlAs LASER. Braz Dent J. 2010;21(4):356-60. http://dx.doi.

org/10.1590/S0103-64402010000400012. PMid:20976388.

27. Khairnar S, Bhate K, S N SK, Kshirsagar K, Jagtap B, Kakodkar P.

Comparative evaluation of low-level laser therapy and ultrasound

heat therapy in reducing temporomandibular joint disorder

pain. J Dent Anesth Pain Med. 2019;19(5):289-94. http://dx.doi.

org/10.17245/jdapm.2019.19.5.289. PMid:31723669.

28. Desai AP, Roy SK, Semi RS, Balasundaram T. Efficacy of low-level

laser therapy in management of temporomandibular joint pain:

a double blind and placebo controlled trial. J Maxillofac Oral

Surg. 2022;21(3):948-56. http://dx.doi.org/10.1007/s12663-021-

01591-4. PMid:36274894.

29. Gavish A, Winocur E, Ventura YS, Halachmi M, Gazit E. Effect of

stabilization splint therapy on pain during chewing in patients

suffering from myofascial pain. J Oral Rehabil. 2002;29(12):1181-

6. http://dx.doi.org/10.1046/j.1365-2842.2002.00994.x.

PMid:12472855.

30. Klasser GD, Greene CS. Oral appliances in the management

of temporomandibular disorders. Oral Surg Oral Med Oral

Pathol Oral Radiol Endod. 2009;107(2):212-23. http://dx.doi.

org/10.1016/j.tripleo.2008.10.007. PMid:19138639.

31. Abdel-Gawwad EA, Abdullah AA, Farhat MY, Helal MA. Eﬀect

of using Photobiomodulation, stabilization, and anterior

repositioning splints on the pain level of subjects with

temporomandibular joint disc displacement with reduction.

BrazDentSci. 2021;24(4 Suppl 1):1-8. http://dx.doi.org/10.4322/

bds.2021.e2670.

32. Al Quran FA, Kamal MS. Anterior midline point stop device

(AMPS) in the treatment of myogenous TMDs: comparison with

the stabilization splint and control group. Oral Surg Oral Med

Oral Pathol Oral Radiol Endod. 2006;101(6):741-7. http://dx.doi.

org/10.1016/j.tripleo.2005.04.021. PMid:16731393.

33. Türp JC, Komine F, Hugger A. Efficacy of stabilization splints

for the management of patients with masticatory muscle

pain: a qualitative systematic review. Clin Oral Investig.

2004;8(4):179-95. http://dx.doi.org/10.1007/s00784-004-

0265-4. PMid:15179561.

34. Matsumoto H, Tsukiyama Y, Kuwatsuru R, Koyano K. The effect

of intermittent use of occlusal splint devices on sleep bruxism:

a 4‐week observation with a portable electromyographic

recording device. J Oral Rehabil. 2015;42(4):251-8. http://dx.doi.

org/10.1111/joor.12251. PMid:25363423.

35. Ceneviz C, Mehta NR, Forgione A, Sands MJ, Abdallah EF,

Lobo LS, Mavroudi S. The immediate effect of changing

mandibular position on the EMG activity of the masseter,

temporalis, sternocleidomastoid, and trapezius muscles. Cranio.

2006;24(4):237-44. http://dx.doi.org/10.1179/crn.2006.038.

PMid:17086852.

36. Vrbanović E, Alajbeg IZ. Long-term effectiveness of occlusal

splint therapy compared to placebo in patients with

chronic temporomandibular disorders. Acta Stomatol Croat.

2019;53(3):195-206. http://dx.doi.org/10.15644/asc53/3/1.

PMid:31749451.

37. Kuzmanovic Pficer J, Dodic S, Lazic V, Trajkovic G, Milic

N, Milicic B. Occlusal stabilization splint for patients with

temporomandibular disorders: meta-analysis of short and long

term effects. PLoS One. 2017;12(2):e0171296. http://dx.doi.

org/10.1371/journal.pone.0171296. PMid:28166255.

Braz Dent Sci 2023 Oct/Dec;26 (4): e3940

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

Farahat AMS et al.

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial

Farahat AMS et al.

Eﬀect of low-level LASER therapy versus CAD/CAM Michigan

splint on patients with Temporomandibular Muscle Disorders: a

randomized clinical trial

Date submitted: 2023 June 22

Accept submission: 2023 Oct 06

Amany Mostafa Saad Farahat

(Corresponding address)

Ain Shams University, Lecturer of Oral and Maxillofacial Prosthodontics

Department, Cairo, Egypt.

Email: dr.amany.m@dent.asu.edu.eg