Articulo Fono y Bruxismo

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ANATOMY

Electromyographie Analysis ofthe Masseter andBuccinator Muscles with the Pro-Fono Facial ExerciserUse in BruxersRenata S.R. Jardini, M.Sc: Lydia S.R. Ruiz, M.Sc. Ph.D.:Maria A.A. Moyses, M.Sc. Ph.D.

0886-9634/2401-029$05.00/0,THEJOURNAL OFCRANIOMANDIBULARPRACTICE,Copyr ight 2006by CHROMA, Inc,

Manuscript receivedJuly 29. 20 03: revisedmanuscript receivedJune 28, 20 04: acceptedAugust 19, 2004Address for reprint requests:Dr. Renata S.R. JardiniAv, Joaquim deSouzaPinheiro 58Araraquara 14802-020Brazil, SAE-mail: [email protected]

ABSTRACT: The aim of this study was to evaluate the efficiency of the Pro-Fono Faciai Exerciser (Pro-Fono Productos Especializados para Fonoaudiologia Ltda.,, Barueri/SP, Brazil) to decrease bruxism, asweil as tine correlation between the masseter and the buccinator muscies using eiectromyography(EMG). in this study, 39 individuals ranging from 23 to 48 years of age were seiected from a dentalschool and then underwent surface EMG at three different periods of time: 0. 1 0, and 70 days. Theywere divided into a normal control group, a bruxer control group (withoul device), and an experimentalbruxer group who used the device. T he bruxer group showed a greater m asseter EMG amplitude wh encompared to the normal group, while the experimental group had deceased activity with a reduction insymptoms. The buccinator EMG spectral analysis of the expenmentai bruxist group showed asynchro-nous contractions of the masseter muscie (during jaw opening) after using the Pro-Fono FacialExerciser. The normal group aiso showed asynchronous contractions. Upon correlation of the databetween these muscles, the inference is that there is a reduction in bruxism when activating the bucci-nator muscle.

Dr. Renuta S.R, Jardini is a phonoaudi-ologisi with a M .Sc. degree and is agraduate sliident in the Department ofChild and Teenager Health. University ofMedical Sciences. 11 NICAM P. Campinas.Sao Paulo, Brazil.

In a multidisciplinary approach, essential for retrain-ing the stomaiognathic system, the need for the con-certed efforts of physiotherapists, dentists, and speechtherapists is eviden t. The sy.stem cons ists of two differentgroups of oral structures, static or passive structures anddynamic or active structures, which are balanced andcontrolled by the central nervous system and are respon-sible for proper functioning of the facial muscles.The buccinator is a deep muscle with large dimen sions

which forms the lateral wulls of the mouth and constitutesthe essential muscles of the cheeks. It participates in com-plex movements of the face, in the creation of facialexpressions, varying its muscular activity intra- and inter-individually, active when sucking and blowing, mainlywhen cheeks are expanded. This m uscle also collaboratesin the lateralization of the corners of the mouth in smil-ing, together with the zygomatic. the risorius, and the Icv-ator muscles.'-'Sicher and DubruH reported that the huecinator musclerelaxes during the jaw -ope ning phase and contractsduring jaw-closing. It functions as an auxiliary to the

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PRO-FONO EXERCISER USE IN BRUXERS JARDINI ET AL.

iiiuscle.s of mastication, keeping the necessary tension inthe cheeks and preventing them from folding and beingbitten by the teeth. Liorca'^ and Hanson and Barrett'' quoteits function as a muscle that harmonizes the facial mus-cles, and Lundquist.' De Sousa and Vitti.** and Blanton, etal.'' all reported through EMG evaluation that the bucci-nator musculature is auxiliary to, though not responsiblefor mastication. It participates in the jaw-opening phaseand Is nol synchronized with masseter muscle activity.

Among oral parafunctions, bruxism is of major interestand can be defined as"nonfunctional tooth eontact,"'""characterized by teeth clenching or grinding., which canoccur during the day or at night. Although many theorieshave been presented since the l%Os, bruxism etiologyand pathophysiology is still unknown. It has been calledocclusal in origin.'-but this theory is rejected by Rugh, etal.'^ and Okeson.'^ since not all patients respond favor-ably to occlusal adjustment. Bruxism has also beenrelated to biopsychosocial factors.'^ "' sleep disorderedbreathing.'^ or temporoman dibular disorders (TMD ),"*''''yet with no cause/effect definition.'*'

With regard to the epidemiology, there is controversydue to the differences in methodologies employed, whichleads tobruxism frequency ranging from 15-90^^: oftheadult population."'^-'There are similarities in symptomatology findings, i.e.,nonfunctional standards of teeth wearing, teeth fracturesand restorations." -' increased tonus and masseter hyper-trophy, articular locking or limitation, articular clicking,popping or clicking sounds, fatigue of the masticatorymuscles upon waking or during sleep, headache, peri-odontal and endodontal implications."-"-'The Pro-Fono Facial Exerciser was created and devel-oped by this author to concentrate and increase the effi-ciency of the exercises proposed for retraining facialmuscles, supported by former EMG studies on facial flac-cidity.-^ Signs of buccinator muscle interference in mas-seter muscle activity have been detected in other studies.These studies motivated the present research, since thereare no referential data in the specialized literature.The objectives of this study were to evaluate the effi-ciency of the Pro-Fono Facial Exerciser as a device toreduce bruxism and to assess a possible correlationbetween the buccinator and the masseter mu.scles usingEMG evaluation.

Materials and Methods

In this study, 39 individuals ranging in age from 23 to48 years were selected from a dental school in Sao Paulo,Brazil. Most subjects were students or former students ofthe school. They agreed to an evaluation protocol admin-

istered by the same researcher. The diagnosis of bruxismused to select symptomatic individuals was based uponclinical studies by Kopp,--* Seligman and Pullinger,-'^Lobbezoo and Lavigne,-" Attanasio." and Okeson,-'' toverify the presence of tooth wearing facets on the anteriorocclusal surfaces ofthe incisal and posterior teeth, alongwith wear in the canine region. Also taken into consider-ation was a questionnaire completed by subjects as part oftheir clinical examination. The questionnaire showedwhether there was muscular or ar t icular tenderness ,fatigue or stiffness of the masticatory muscles on awak-ening or at the end ofthe day. difficulties in mandibularopening, and even masseter hypertrophy, asdescribed instudies by Rugh and Harlan.'^ Dahlstrom, et al..-^ andGonzalez and Muller.''^ In the present study, the individu-als were not differentiated according to et io logy ordegree of severity of their symptoms. This aspect will beanalyzed in future research studies.

The exclusion criteria for all volunteers were: a. threeor more missing teeth; b.Class II or Class III occlusionaccording to Angle,- ' ' (in order to avoid any possibleinterference in neuromuscular patterns due to malocclu-sion); c. systemic disease which could affect the neuro-muscular system; d. use of medications that could retardmuscle movement or cause muscular force loss; and e.former (up to six months before) orcurrent phonoaudio-logical treatment of the oral musculature, facial physio-therapy, or electrostimulation.In order to avoid any interference in the result inganalysis, volunteers were asked to suspend the use of oralsplints while participating in the study.The individuals were divided into three groups consist-ing of 13 individuals in each, as follows: (GI) controlgroup consist ing of normal individuals: (G2) bruxercontrol group; and (G3) experimental bruxer group usingthe Pro-Fono Facial Exerciser after the first EMGassessment.All individuals were given specific details ofthe studyand the EMG evaluation, and signed an Informed Consentapproved by the Ethics Commit tee . They were a lso

infonne dof the details of the EMG evaluation. Before theEMG evaluations, the volunteers were instructed andtrained on the tests tobe performed as follows: a. contin-uous blows for 5-seconds at three different times (isomet-r ic contraction of the buccinator ) , wi th one-minuteintervals belween contractions while keeping cheekstaut, resulting in three experimental values: b. three 5-second isotonic masticatory cycles u.sing Parafilm(American National Can, Chicago, IL) interposed, bilat-erally between the posterior teeth, with a 2-minute restinginterval. The results ofthe three cycles were averaged.EMG Evaluation


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JARDINI ET AL. PRO-FONO EXERCISER USE IN BRUXERS

The EMG registrations were completed at theElectromyography Laboratory of CEDEFA CE - Oral andFacial Deformities Research and Treatment Center inAraraquara. Brazil, using a Sign Conditioner Module -Lynx M CS V2, 16 channe ls. Sign Acquisition System(SAS) (Lynx Tecnologia Elcctronica Ltda., Sao Paulo.Brazil), w ith 12-bite dynamic band resolution, Butterworth(Lynx Tecnologia Electronica Ltda., Sao Paulo, Brazil)high pass filter of 10.6 Hz and low pass filter of 509 Hz.with a 2000 gain range and converse plate of analogicalsign into digital sign (A/D). For the simultaneous presen-tation of the signs collected from the four channels byfour surface differential silver electrodes. AQDADOSsoftware (Lynx Tecnologia Electronica Ltda., Sao Paulo,Brazil) was used allowing sign treatment in an RMS rate,mean, minimum , maxim um, and standard deviation, witha sampling frequency of 1000 Hz. based on the orienta-tion protocol for EMG signs recording in the ./oumal ofElectromyography and Kines'iology.'"

A preliminary study with ten volunteers chosen for thisphase of the trial was performed before data collectionbegan and was used to standardize the routine. This pre-liminary study assisted with choosing materials and tech-niques in order to obtain EMG signs from the buccinatorand masseter muscles.The surface electrode placement on the buccinatormuscle was based upon previous studies.'' referring tothe intersection ofthe horizontal plane ofthe labial com-missure with the vertical plane ofthe visual externalangle, in each hemi-face, making a right angle (90),standing the subject at a 45 angle to the examiner. Forthe masseter muscle, the electrode was placed on its mus-cular maximal bulk.- A referential electrode was attachedto the right wrist of each subject.All subjects were subjected to three EMG evaluationsat 0. 10, and 70 days (respectively. TO, T l. and T2). Theexperimental bruxer group started using a Pro-FonoFacial Exerciser at the first evaluation. For each timeperiod mentioned (TO, Tl, T2), three experimental datasets were collected from each of the 13 subjects (nine perindividual).

TreatmentPro-Fono Facial Exerciser DescriptionThe Pro-Fono Facial Exerciser consists of two flatacrylic bases of about 2x4 cm each, which fit intraorallyin the vestibular region of the cheeks and are supportedby the right and left labial angles. The two acrylic basesare joined by two I-mm stainless steel wire shank s,which are 12 cm long with a spring in the middle of eachwire (Figure 1).

To use the Pro-Fono device, the acrylic bases areplaced intraorally. The undercuts fit on ihe right and leftmoulh angles, allowing ihe device wires to be outside themouth with no tooth contact. When inserted in the mouth,[he device stretches the mouth horizontally using aspring-force effect. T he user compres.ses the checks to tryto close the device w ith close to eight teeth, but not touch-ing them, thus contracting the involved muscles. The lipsremain open with the teeth exposed and in natural contactwithout clenching (^Figure 2).

Recommended exercises were: a. to close the deviceslowly using compression force of the cheeks, and toslowly release it relaxing the muscles and repeating thismovement 20 times. This is an isotonic exercise, wherethere is length variation in muscular fibers, based uponthe principle of movement resistance, which favors thepractice-''; and b. to close the device keeping the com-pression force ofthe cheeks for 15-20 seconds. This is an

Figure IThe Pro-Honn Facial h^xcrciser (Pro-Fono Prniiutos Especializadospara Fonoaudiokigia Ltda.. Barueri/SP. Brazil)

Figure 2Photo showing correct use ofthe Pro-Fono Facial Exerciser.

JANUARY 2006, VOL. 24. NO. 1 THE JOURN AL OF CRANIOMAN DIBULAR PRACTICE 31


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isometric exercise, where there isno length variation Inmuscular fibers, allowing for better control of movementand keeping mobility steady, as well as generating highertension on muscular fibers.-*-These exercises, as well as Ihe recommendations for

their use, are explained in the device instruction booklet.Initially, the exercises were performed at the clinic by theexperimental group and later practiced athome. The fre-quency indicated was from 1 to 3 exercise series, whichthey couid divide upduring theday. The goal was toreach a maximum time of 15 minutes daily, according tothe subject 's tolerance to allow for minimal pain ordiscomfort.Statistical Analysis

During the data processing, the non-normalization ofthe EMG sign was accepted in order to avoid the loss ofthe amplitude differences reached during treatment.Therefore, it was possible to analyze the Pro-Fono FacialExerciser as a therapeutic device.-''^The control groups were analyzed using Wilcoxon'stest for two related samples. The correlation between thebuccinator and masseter muscles was analyzed utilizingPearson r coefficients and a chi-square test. The spectralEMG analysis was done using a chi-square test and forsymptom evaluation, the sampling standard deviationwas studied. For all the tests in this study, an alpha sig-nificance level of 5% (a=0.05) was chosen.

ResultsControl Groups (Wilcoxon)

For control groups GI (normal) and G2 (bruxers), therewas no significant difference among the collections foreach subject, i.e., TO=T1=T2. for both tbe buccinator andmasseter muscles, indicating that each group can beexpressed by its means. In all the analyses. p>().05 wasobtained using the W ilcoxon test. Therefore, BG l is con-sidered the mean of normal group buccinators, and BG2the mean of the bruxer control group, while MGI andMG2. respectively, are the means for the masseter mus-cles. Mean values are. respectively: BGI-14.930.46:MGI=43.271.I2: BG2=13.210.40; MG2=64.681.99.Correlation Between Buccinator and Masseter Muscle.';(Pearson ri

Table 1 shows that the correlation analysis resulted inr,,,^,j=-0.927. based on data collected during the three exer-cise sets performed by each of the 13 subjects. The datashowed a definite relationship between the electricalactivities of the masseter and buccinator muscles, i.e.. the

buccinaior increase is related to the masseter decrease(Graph 1). This does notmean, however, that there is acause/effect relationship.Electromyo}>rapluc Spectral Analysis (chi-square)

The following criteria were adopted (Figure 3): mark0, absence of asynchronous contraction: mark 1. weaktendency of asynchronous contraction of the buccinatormuscle: mark 2, strong tendency of asynchronous con-traction of the buccinator muscle: mark 3. defined asyn-chronous contraction ofthe buccinator muscle.For GI as well as for G2, the chi-square test confirmedthat the frequencies of marks 0. 1.2. and 3 all have dif-ferent values {Tables 2 and 3). It can be observed in GI(normal) that mark 3 is the most frequent, indicating thatnormal subjects feature asynchronous contraction. Mark0 is the most frequent in G2 (control bruxers). indicatingthat bruxers do not feature asyn chronous contraction.The correlation between mark 3 and mark 0 is 0.931 inG3 (experimental bruxers) (Table 4). Mark 0 decreasesfrom TO to T2 while mark 3 increases from TO to T2(Graph 2). G3 showed asynchronous contractions afterexercise.Analysis of the relationship among groups GI, G2, andG3 makes it possible to conclude that bruxers from thecontrol group were equal toexperimental bruxers beforetreatment: G3T0=G2(O.O5


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Table 1Correlation of Buccinator and Masseter Data, Pearson r Coefficientn=13

Subject/timemo1/T11/T22/TO2fT^2/T2

3/TO3rT2AfTO4/T1Am5/TO5/T15yT26/TO6 T 16/T27/TO7/T17n"28/TO8/T18n"29/TO9n"i9/T2ion-oion"i10/T2iirroiin"212/TO\2fT^A2fT2

13/TO13m13/T2

Buccinator aven14.262.4611.332.0524.092.3011.492.6413.163.0114.741.806.903.4716.487.0815.003.379.161.4620.085.5541.1114.305.651.1119.897.2924.806.396.400.659.515.6211.043.126.601.558.391.9214.352.698.31 1.9914.244.8721.788.218.792.8211.562.5719.355.736.710.729.411.1519.635.999.211.9311.34+3,7410.054.42

13.664.7014.947.4815.796.8313.472.5113.41 5.5618.593.88

Masseter average175.8222.97167.258.05129.3813.62111.869.1654.007.1344.704.4136.109.6031.725.4625.524.1982.447.2470.055.4358.485.1381.3137.3065.8419.7055.8725.21

130.6221.08113.6117.7697.34 14.0845.3318.3840.8710.7629.514.3846.444.2132.063.6530.394.4156.824.8751.935.3649.044.23

102.53.25.7393,226.5167.6013.2769.5024.5837,7310.8341.01+4.7689.6916.8197.908.7666.179.2144.664.0738.964.7635.01 11.84

-0.923

-0.928

-0.918

-0.980

-0.989

-0.960

-0.999

-0.879

-0.915

-0.915

-0.850

-0.998

-0.803

JANUARY 2006, VOL. 24. NO. 1 THE JOURNAL OF CRANIOMANDIBULAR PRACTICE


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140

'Olts

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Table 2Correlation Between G1 and Marks, Chi-SquareTest for One Samplen=13

TimeTOT l

MarkO1601

Mark0 611

1 M ark 21515

Mark4 151

3 P


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oGraph 2Asynchronous coiUraclion of Ihebuccinator muscle in G3.

T1nT2

Mark 0 Mark 1 Mark 2 Mark 3Vitti** and Bhinlon. et al.'' As demonstrated in the presentstudy, Ihe bruxcr subjects lost or drastically minimizedthe intercalated contraction, asynchronous with the mas-seter muscle. The intercalated contraction is recoveredwith buccinator muscle activation while using the Pro-Fono Facial Exerciser to minimize symptoms.

These are precedents for the multifactorial analysis ofbruxism etiology, which were related and associated inthe current article with the facial musculature rehabilita-tion for the group studied. This is especially true withbuccinator strengthening, supported with the use ofthePro-Fono Facial E xerciser.References

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Articulo Fono y Bruxismo