The Effects of Position on Mandibular Muscle Activity

Charles R. Carlson, PhD The purpose of this study was to determine the relationship Jeffrey J. Sherman, MA between tongue position and mandibular muscle activity. Thirty- three subjects (28 tvomen) between the ages of 18 and 34 years Jamie L. Studts, MS (mean = 22.1 years) with no prior injury to or pain in the , Department of Psychology and , or tongue participated in the study. Subjects were asked to Orofaeial Pain Center rest quietly while baseline electromyographic recordings were University of Kentucky made from the temporaiis, masseter, and suprahyoid muscle Lexington. Kentucky regions. Afterwards, subjects were randomly assigned to condi- tions requiring them to position the tongue either "against the Peter M. Bertrand, DDS anterior " or "on the floor of the mouth, making sure the tip National Navai Medical Center Bethesda, Maryland does not press against any part of the mouth." The results indi- cated that right temporaiis activity was higher when the tongue Correspondence to: was positioned against the roof of the mouth than when it was Dr Charles R. Carlson, PhD either at baseline or resting on the floor of the mouth (P < .03). A Department of Psychology similar pattern of results was observed for the suprahyoid muscle 112 Kastle Hall group (P < .01). There were no significant differences in masseter University of Kentucky muscle activity as a function of tongue position (Ps > .20). These Lexington, Kentucky 40506-0044 findings suggest caution in labeling the "rest" position of the Fax: (606)323-1979 tongue and indicate that further study of the relationship between tongue position and orofacial pains is needed. I OROFACIAL PAIN l997;ll:291-297.

key words: muscle activity, electromyogram, tongue position

ver the past 10 years, experimental data in the fieid of temporomandibular disorders (TMD) are forcing health Opractitioners to revise their understanding of the etiology and maintenance of these phenomena. Issues such as the reiation- ship between and TMD pain, the so-called vicious cycle of muscle tension and pain, and the effectiveness of occlusal splint therapy have been examined under more stringently controlled sci- entific conditions.''- With the efforts of many clinical researchers, well-designed research studies have hegun to establish a founda- tion of knowledge upon which to develop treatment options. It is from within that tradition that the current study was conceived. It is common for dental and physical therapy practitioners to instruct patients on the correct "rest" position for the tongue.^"-^ Rocahado's 6X6 program^ for treatment of craniocervical and craniomandibular system disorders emphasizes that the dentist must teach the patient the correct "rest" position of the tongue. Specifically, he recommends that the should be maintained against the palate with slight pressure. Rocabado fur- ther states that in this position, masticatory muscle activity is at a

Journal of Orofacial Pain 291 Carlson et al

minitnum. No scientific data in the lirerature, from instructions that the usual and customary rest either in the form of electromyography (EMG) or position of the tongue is on the roof of the inunrh. self-report findings, were found to substantiate this The present investigation was conducted tn IIIL:;I- claim. Therefore, this recommendation concerning sure the activity in masticatory muscle grmiRS the "rest" position of the tongue currently may be wben the tongue is placed either on the palate or hased more on clinical lore than on data derived on the floor of the mouth. It was predicted that from careful scientific study. positions of the tongue requiring even slight pres- sure or overcoming gravitational forces (ie, tongue Both the degree of muscle activity associated on the palate) would involve greater muscle activ- with tongue positioning and the association be- ity in the orofacial region than would positioning tween tongue position and the development or the tongue without pressure and resting it on the maintenance of TMD are unclear at this point. bottom of the mouth. Intuitively, this resting posi- However, there are some reasons for concern with tion would not involve muscle activity or energy labeling rhe tongue placement on the roof of the expenditure to oppose the force of gravity, unless mouth as a "rest position." First, maintaining pres- the weight of the and tongue would sure agaitist rhe palate would require recruitrnent require an increase in elevator muscle activity to of some muselé fibers, and such muscle activity maintain the position. Scientific studies of tem- would be tnconsistcnt with the term "rest." Sec- poromandibular functioning are important in iden- ond, if the person were upright, muscle activity tifytng those factors contributing to the develop- and energy would need to be expended to over- ment and maintenance of dysfunction from those come the force of gravity. Goodheart' describes that anecdotally appear to play a role. the difference hetween what a dentist might call a "physiologic rest position of the mandible" and what a physiologist might tertn the "postural posi- tion of the mandible." He states that the term Materials and Methods "physiologic rest" is inappropriate because the postural position of the mandible requires the mus- Subjects cles innervated by the fifth to contract iust enough to hold the mandible in a balanced state of Thirty-three subjects (28 women) ranging in age equilibrium against gravity. It is difficult to know from 18 to 34 years were recruited from a univer- where this balance lies for the tongue and its sup- sity community to participate in this study. Sub- porting muscles. Third, the constant maintenance jects were screened prior to participation and were of the tongue in this position, if it is not the "nor- excluded if they had any current or prior injury to mal" position, has the potential to produce muselé or pain in the jaw, mouth, or tongue. All subjects fatigue and discomfort because of the effort re- gave informed consent after the procedures and quired to maintain a "relaxed" position.^ hi sum- the voluntary nature of the experiment had been mary, "resting" the tongue against the roof of the explained. While gender representation is obvi- oral cavity with slight pressure very likely involves ously imbalanced, this proportion (85% female) is the use of muscle activity. Without controlled lab- representative of the patients seen for treatment of oratory experiments, however, tbis proposition facial pain complaints.'' Twenty-nine (93.5%) cannot be evaluated. subjects described themselves as Caucasian, two In some cases, there may be a reasonable clinical (6.5%) described themselves as African American, rationale for placing the tongue on the roof of the and two declined to answer. The average height mouth. For example, some patients have excessive for participants was 5 ft 6 in (SD - 29 in). Average translation of the mandible during rotational move- weight was 137 Ih (SD = 29 Ib), and average age ments. With such persons, it is conceivable that was 22.1 years (SD = 3.4 years). This research was correct ¡aw alignment may be obtained by placing approved by the institutional Review Board for the the tip of the tongue on the roof of the tnouth dur- Protection of Subjects at the University of ing mandibular rotation.^ Further, to restore ap- Kentucky. propriate mobility and to strengthen the mastica- tory muscles after soft tissue injury or surgery, opening and closing the mouth with the tip of the Experimental Setting tongue on the palate enables the patient to exercise Ail procedures were conducted in a sound-attenu- the muscles within a conrroMed range while re- ated room at tbe Orofacial Pain Genter of the training tbem in proper rotational movement.^ University of Kentucky. Participants were seated However, such instructions are distinctly different upright in a cushioned chair with head support.

292 Volume 1 1. Number 4, 1997 Carlson et al

Electromyograph Recordings tongue positions. The order of tongue placement Physiologic measures were recorded using a J&J was randomly assigned. Seventeen subjects began 1-330 compnterized physiograph (J&J Enterprises, with instructions to place the tongue on the roof Poulsbo, WA), which integrated data over l-sec- of the mouth. ond intervals during the data collection trials. During all trial periods, suhjects were asked to Electromyograph sites were monirored using 0.5 keep their and teeth slightly apart to control cm- silver/silver chloride surface electrodes. The for facial positioning and to minimize extraneous surface of the skin was cleaned and abraded with movements. While this is also a modification of Rocabado's original instructions, this position has an alcohol swab, and elecrrolyte paste was applied been identified by Rugh and Drago'^ as the posi- to the EMG electtodes before they were attached tion of the mandible at which activity of the mas- to the sktn surface with adhesive collars. The ticatory muscles is minimal. These instructions EMG electrodes were then placed hilaterally on were also included in order to reduce the error the masseter muscles and on the right temporalis variance associated with the multiple positions of muscle according to procedures descrihed by the mandible that subjects might assume. Carlson et al.'"'" Electromyograph electrodes Complete instruction sets are given in Appendix were also placed on the suprahyoid muscle region 1. For each position of the tongue, the full instruc- as descrihed by Lemke and Van Sickels.'- The tions were given at the beginning of the first two monitoring was restricted to these four sites trials and then abbreviated for the last trial, either because a maximum of four EMG channels could as, "up on the roof of your mouth" or as "down be monitored with the available equipment. on the floor of your mouth." All subjects alter- nated positions until three trials were recorded in both positions. Upon completion of the evaluation Procedures session, electrodes were removed and subjects were debriefed and thanked for their participa- All subjects were screened for health history and tion. inclusion criteria. Once these criteria were met and informed consent was obtained, EMC elec- trodes were attached and checked for comfort, and the EMC signals were observed to ensure that Data Analyses no artifact or electrical mterference was present in All analyses were performed using the SAS statis- the signal. After an adaptation period, wherein tical software program.''' Baseline EMG activity the EMC signals stabilized, all subjects rested qui- was calculated by averaging readings for the five etly during a 5-minute baseline period while phys- 1-minute periods of rest. Mean physiologic activ- iologic recordings were made. During this and all ity level during trials was calculated by averaging recording periods, subjects were asked to sit as EMG readings for the three time periods when quietly and comfortably as possible and to refrain subjects placed their on the roof of the from unnecessary movements. After the baseline mouth and on the floor of the mouth. period, ali subjects were cold that they would be Eiectromyographic activity ar basehne was com- instructed to alternate the position of their tongue pared with activity vifhen the tongue was at the so that the tip of the tongue would be placed on roof and on the floor of the mouth using repeated the roof or floor of the mouth. They were also measures analysis of variance (ANOVA). Paired told that each trial of tongue position would last comparison ¡ tests were used to evaluate a priori for 1 minute. Subjects were then instructed either hypotheses. The advantage of a repeated measure to place the anterior third of the tongue on the design wirh EMC recordings is that each subject roof of the mouth according to modified guide- serves as her/his own control.'^ This is important lines explained by Rocabado,'' or to resr the because EMG activity can be influenced by such tongue on the floor of the mouth. The interested factors as skin preparation, site placement, age, reader is encouraged to refer to the original and subject morphology.^ instructions by Rocabado, which also include instructions to breathe through the nose and to use the diaphragm muscle, in addition to "main- Results tain¡ing] the anterior third of the tongue against the palate with slight pressure."^P^'*^ Suhjects were Thirty-three subjects completed the study. To ver- given instructions that were as close to this as pos- ify random assignment, analyses were conducted sible except for the specifications regarding to ensure that the group which started with the

Journal of Orofacial Pain 293 Carlson et al

Table 1 Electron! y o graph Activity Site Baseline Root" [H Floor (^iv) Pose baseline (HV) P Right masseter 2.38(3.24) 2,42(1,31) 2.33 (1 30) 2,01 (1,02) ,a3 Left masseter 2.67(1 15) 2.48(1,13) 2 30 (.80) 2,27(1,03) .20 3.22(1,99) Right temporaiis 3.07(1.78) 3 50(1.79) 3.06(1.75) .03 3.33(1.60) ,01 Suprahyoid 3 02 (0.32) 4 23 (2.33) 3.35 (2 07) Stenderd deviatic «I il

instrucrions to place the tongue on the roof of the The use of EMG records to determine the rest- mouth did not differ on any demographic variable ing position of the mandible has been criticized from the group which started b>' allowing the by Lund and Widmer,' They were especially criti- tongue to rest on the floor of rhe mouth (Ps > .05), cal of the use of EMG in the establishment of There were no significant differences for EMG proper rest and occlusal positioning. Since some activity in rhe right {¥ [2,30] = 0.19, P < .83) or degree of muscle activity is necessary at all times, left masseter muscles (F [2,24] = 1.72, P < ,20), and since differences between subjects in age, regardless of tongue position. The repeated mea- sex, and facial morphology influence EMG read- sures ANOVA for rhe right temporalis (F [2,29] = ings, they suggested that "there is no evidence 3.96, P < ,03) and for the suprahyoid region (F that the clinical rest position can be determined [2,28] = 5,46, P < .01) reached significance. A pri- on the basis of some standard level of postural ori contrasts revealed that EMG activity in the activity , , . because of differences between mus- right remporalis was significantly higher (f [1,32] = cles and between subjects."'P^-^ We agree with 2.83, P < .01) when the tongue was on the roof this view. It is important to note, however, that rather than on the floor of the mouth. Contrasts the present study used a within-subjects design, for the suprahyoid muscle region revealed that where each subject served as his or her own con- EMG activity was lower at baseline than when the trol to adjust for the influence of the age, sex, tongue was either on rhe roof (i [30] = 3.35, P < and facial morphology variables. Further, our .01) or on the floor (i [31] = 2.43, P < .05) of the data are reported in terms of relative differences mouth. Further, HMG activity in the suprahyoid in EMG activity rather than absolute values rep- region was significantly higher {t [1,32] = 1,S7, P < resenting rest or activity. Therefore, it is reason- .05) when the tongue was on the roof of the mouth rather than on the floor of the mouth. able to conclude that relative changes in muscle These results are presented in Tahle 1. activity would be comparable within subjects as they altered positions. Based on the present data, positioning the tongue on the floor of the mouth with specific instructions minimizes muscle activ- Discussion ity in comparison to placing the tongue on the roof of the mouth with instructions. The principal finding of this study was that mus- Despite the current discussions concerning the cle activity was increased in the suprahyoid and lack of a relationship between muscle activity temporalis regions when the tongue was posi- and pain reports in controlled experiments,^'^ tioned on the anterior palate and maintained in finding a position of relaxation for the tongue that position with slight pressure as compared to and is often identified as an positioning the tongue on rhe floor of the mouth. important step in the clinical management of This study also found that muscle activity in the orofaciai pain. Previous publications in the fields masseter region was nor altered as a consequence of physical therapy and dentistry suggested that of tongue placement. Although the range of the a key component of the rehabilitation of biome- EMG differences was small, it does support the chanical dysfunction of the temporomandibulat premise that it is inaccurate to instruct patients to (TMJ) requires the patient to learn new place the tip of the tongue on the roof of the postural relationships in order to maintain the mouth as a means of relaxing the masticatory orthostatic ei^uilihrium of the upper body.'' muscles. Often these programs include instructions for

294 Voiume 1 1, Number 4, 1997 Carlson et a!

posmotiing the tongue during rest. Positioning search to establish the relationships hetween tongue the tongue so rhat the anterior third of the posición, muscle activity, and developmental out- tongue pushes agamst the palate with shght pres- comes. sure IS assumed to be the rest position because it The logic of the argument for the tongue's resting is viewed as basic to normal . There is position on the palate is hard to follow when reason to believe that this tongue position may instructions to "maintain the position with slight help to prevent excessive translation of the jaw pressure" are given to patients. It seems reasonable during tiormal rotation, but the scientific evi- to infer from our data that this slight pressure comes dence that the tongue's physiologic rest position at the cose of increased suprahyoid and cemporalis is generally on the roof of the mouth is lacking. region activity. Maintaining this elevated position of Our data suggest that temporalis and suprahyoid the tongue when a person is sitting or standing is region muscle activity is higher when the tongue likely to require force to overcome gravity unless it is placed on the roof of the mouth than when che IS done by supporting internal structures. Given our tongue is on the floor of the mouth. Based on findings, we suggest that instructing paciencs to rest these data, it would be imprudent co state that their facial muscles by placing the tongue on the the "rest" position of the tongue is on the roof roof of the mouth with slight pressure against the of the mouth. We acknowledge, however, that palate is a practice that needs to be modified. che degree of muscle activity has yet to be deter- There may be circumstances during which pa- mined when the instructions to place the tongue tients gain therapeutic benefits from placing the tip on the roof of the mouth are accompanied by of the tongue against the roof of the mouth,^ but instructions "to breathe through che nose and to our data would suggest that chis is not a relaxed use the diaphragm muscles for respiration."^P"*' position for . Because the Clinical therapies are often based on logic that range of the EMG differences is relatively small, it precedes accurate biologic explanations for the may be tempting co dismiss these findings as clini- symptoms. Tongue motor function is controlled cally insignificant. Presently, however, we do not by the and responds readily Co have data addressing rhe magnitude of differences in cortical concrol.'* If rhe upper brain is involved EMG activity that correspond to the presentation of in tongue activity, Stressors may activate learned clinical symptoms, and this question remains open parafunctions, such as placmg the tongue on the for further scrutiny. In the view of Lund and palate. Our data show that tongue position Widmer,^ however, EMG activity as it is currently maintained on the roof of the mouth by slight measured in the laboratory and clinic has not gener- ally been shown to be a factor in the genesis and pressure involves masticatory and cervical mus- maintenance of orofacial pains. Ultimately, the cles. It is possible thac such learned tongue posi- actual position of the tongue and the muscle activity tioning could result in perceived muscle fatigue involved may prove to he inconsequential so long as or pain for some individuals. people minimize rhe use of pressure or force against The issue of normal tongue posición and other structures of die masticatory system. proper development of the ora) cavicy has heen of significant interest to dentistry. For instance, Seventeen of the 33 subjects in the present study Subtelny and Sakuda'^ have used cineradio- reported that their tongue usually is on the roof of graphs to evaluate tongue position and Co link their mouth. When they were asked to let the positioning of the tongue to oral cavicy de- the tongue rest on the floor of the mouth, velopment. Proper oral cavity development re- they reported feelings of awkwardness. We are portedly requires pressure from the tongue on presently conducting a follow-up srudy co determine the roof of the mouth. This research and related whether or not the "normal" position of che congue studies evaluating tongue position by using pres- will influence EMG activity of che facial muscles. It sure transducers placed in the oral cavity'^ have IS possible chat adaptation of muscles to routine not, however, generally included direct measure- positions may have obscured our current findings; therefore, we are re-examining this question in a ment of muscle activity via EMG- Moreover, this study that accounts for subjects" reports of the "nor- line of investigation has not provided a definitive mal resting position" of the tongue. It is also possi- answer to the question of what position of the ble that subjects may need several hours or days to tongue would result in the lowest level of muscle practice the experimental instructions so as to mini- activity or what the parameters {time, intensity mize the potential problems associated wich a natu- of force, and so forth) of congue positioning are ral position and the requirements of the experimen- thac affect growth outcomes in the oral cavicy. tal session. Consequently, there is need for additional re-

Journal of Orofaciai Pain 295 Carlson et al

The widespread use of "resting instructions" in References dental and physical therapy environments high- lights our lack of knowledge concerning the etiol- 1. LuijdJP, Widmer CG. An evaluation of the use oí i'"^^'^^ electromyography in the diagnosis, documentation, ana ogy of TMD. Moreover, it is noteworthy that this treatment of dental patients. J Craniomandib Disor J I acial tongue position is often perceived as therapeutic and may even be associated with symptom relief Dworkin SF. Perspectives on the interaction of biological, among patients, even though it is possible that psychological and social factors in TMD. JADA 1994; this position could also be associated with an 125:856-863. increase in symptoms. Many logical arguments Hansson TL, Minor CH, Taylor DL. Physical Therapy in Craniomandib tila r Disorders. Chicago: Quintessence, presented by well-meaning health professionals 1992:45. assist in relieving presenting complaints of TMD. Decker KL, Bromaghin CA, Fricton JR. Physical therapy of In an environment where many therapies for temporomandibular disorders and orofaciai pain. In: TMD are successful, and we often do nor have a Fricton J, Dubner R ¡eds¡. Orofaciai Pain and Temporo- good understanding of why they work when they mandibular Disorders. New York: Raven, 1995:472. do work, caution and prudence are necessary in Kraus SL. Physical therapy management of temporo- mandibular disorders. In: Kraus SL (ed). Temporo- order ro prevent the perpetuation of misinforma- mandibular Disorders, 2nd ed. New York: Livingstone, tion within clinical practice. Actually, the symp- 1994:165. tom relief in TMD may be associated with bio- Rocabado M. Arthro kinematics of the temporomandihular logic events Independent from many aspects of joint. Denral Clinics of North America 1983;27: 573-594. our therapies. Coodheart G. Applied kinesiology in dysfunction of the temporomandibular joint. Dent Clin North Am 1983; We recognize several limitations in the present 27:613-630. study, including: (1) no formal evaluation of the Kroon GW, Naeije M. Electromyographic evidence of local subjects' normal rest positions, (2) no means of muscle fatigue in a subgroup of patients with myogenous ktiowing whether those positions would change craniomandibular disorders. Arch Oral Biol I992;37: spontaneously if subjects were given general 215-218. instructions to relax but were not given specific Rocabado M, Johnston BE, Blakney MG. Physical therapy body movements for accomplishing that task, and and dentistry: An overview. J Graniomand Pract 1983;1: 47^9. (3) no independent analysis of the tongue posi- Carlson CR, Okeson JP, Falaee DA, Nitï AJ, Anderson tion in subjects to ensure their compliance with DA. Stretch based relaxation and the reduction of EMG the position requested. As indicated earlier, we activity among masticatory muscle pain patients. J are taking steps to address these problems in a Craniomandib Disord Facial Otal Pain 1993;5;205-212. follow-up study. It would also be useful to collect Carlson CR, Okeson JP, Falaee DA, Nitz AJ, Curran SL, EMG data from the pterygoid muscle groups. Anderson D. Comparison of psychologic and physio- logic functioning between patients with masticatoty While this would be likely to involve invasive muscle pain and matched controls. J Orofacial Pain 1993; needle EMG recordings, it could be done on a 7:15-22. subsample of subjects to determine whether or I emke RR, Van Sickels J. Electromyographic evaluation of not such muscle groups would be influenced by continuous passive motion versus manual rehabilitation of tongue position. It would also be valuable to col- the tcmpciromandibular joint. J Oral Maxillofac Surg lect Information regarding a subject's ]993;51:I311-1314. of muscle activity in the various positions to Rugh JD, Drago CJ. Vertical dimension: A study of chnical determine whether or not they correspond with rest position and jaw muscle activic;,'. J Prosther Dent 1981; 45:670-675. EMG data. Finally, data from persons reporting SAS. Cary, NC: SAS Institute, 19B5. TM pain should also be obtained because the Fridlund AJ, Cacioppo JT. Guidelines for human electto- presence of pain is known to influence the activ- myographic research. Psjchophysiology 1986;23: ity of masticatory muscles.'^ Even though these 507-589. are important areas for improvement, this study Paxinos G. The Human . San Diego: provides useful information regarding the role of Academic, 1990. muscle activity and tongue position that chal- Subtelny JD, Sakuda M. Muscle function, oral malforma- lenges common assumptions within the field. tion, and growth changes. Am J Orthod 1966;52: 495-517. Prolfit W. Muscle pressures and position: North American whites and Australian aborigines. Angle Otthod 1975;45:1-11. Lund JP, Stohler CS. Effect of pain on muscukr activity in Acknowledgment temporomandibular disorders and reiated conditions. In: Stohler CS, Carlson DS (eds). Biological and Psychological Till! study was supported in part by s granr from NIDR, Aspects of Orofacial Pain, Craniofaciai Growth Series, vo| #ROÎ DE10534-02. 29. Ann Arbor: University of Michigan, 1994.

296 Volume 1 1, Number 4. 1997 Carlson et al

Appendix 1 that the tongue stays comfortably on the roof of Instructional Sets tbe mouth. Also, keep your hps and teeth slightly apart so that the mouth stays in a relaxed posi- Preliminary Instructions: tion" (adapted from Rocabado'). "I'm going to ask you to move your tongue to the top of your mouth and then the bottom of your Tongue on Floor: mouth. We'll alternate positions three times. Each "Begin hy placing your tongue on the floor of your time will last for one minute and then I'll tell you mouth. Make sure you're not pushing against tbe to move it." back of the teeth so that the tongue stays comfort- ably on the floor of the mouth. Just let the tip of Tongue on Roof: the tongue 'flop' to the floor of the mouth and let it lie there until I tell you to move it. Also, keep "Begin by placing your tongue against the anterior your hps and teeth slightly apart so that the mouth palate (the roof of your mouth, near the top, front is in a relaxed position." teeth) and make a clucking sound. Now, maintain the front third of your tongue against the palate with slight pressure until I tell you to move it so

Resutnen Zusammenfassung

Los Efectos de la Posición de la Lengua en Relación s la Die Auswirkungen der Zungenposition auf die Actividad de los Músculos Mandibulares mandibuläre Muskelaktivität

El propósito de este estudio fue ei de determinar la reiación Das Ziel dieser Studie war die Bestimmung der Beziehung zwis- entre la posición de ia lengua y la actividad de ios múscuios chen Zungenposition und mandibulärer Muskeiaktivität. mandibulares. En este estudio participaron 33 personas (28 Dreiunddreissig Personen (28 Frauen) im Aiter zwischen 18 und mujeres) cuyas edades oscilaban entre ios 18 y 34 años (media 34 Jahren (Durchschnitt = 22.1 Jahre) ohne frühere = 22.1 años) Los participantes no habian sufrido iesiones pre- Verletzungen oder Schmerzen im Kiefer, im Mund oder in der vias ni doior en la mandibula. boca o lengua. Se efectuaron reg- Zunge nahmen an dieser Studie teil. Die Personen mussten istros e lect rom io gráficos básales de ias regiones musculares: während der basiselektromyographischen Aufzeichnungen, (tempofai. masetera y suprahioidea), mientras que las personas welche von den Regionen der Mm. temporales, masseteri und descansaban. Luego, los participantes fueron asignados al azar suprahydoidales gemacht wurden, njhig bleiben Anschliessend wurden die Probanden zufallig Bedingungen zugeteilt, welche a dos grupos diferentes, dependiendo de la colocación de la sie dazu aufforderten, die Zunge entweder "gegen den vorderen lengua tJn grupo colocó la lengua contra el paladar anterior. Gaumen" oder in den Mundboden, dabei darauf aciiten, dass otro la colocó sobre el piso de la boca, teniendo cuidado de que die Spitze nicht gegen einen Teil der Mundiiöhe drückt" zu posi- la lengua no presionara ninguna parte de la boca. Los resulta- tionieren Die Ergebnisse deuteten darauf hin. dass die Aktivität dos indicaron que la actividad del temporal derecho era mayor des rechten M. temporalis höher war. wenn die Zunge am Dach cuando la lengua estaba posicionada contra ei paladar, que der Mundhöhle iag. ais wenn sie entweder in Grundsteiiung cuando estaba en la posición basal, o sobre el piso de la boca oder im Mundboden bieibe (P <:.O3). Ein ähniiches Muster von (Pí 0,03). Se registraron patrones similares en los resultados Resultaten wurde für die suprahyoidale Muskeigruppe observados en el músculo suprahioideo íP < 0.01) No se beobachtet (P <.O1 ). Es gab keine signifikanten Unterschiede ir observaron diferencias significativas en la actividad muscuiar de Masseteraktivitat als Funktion der Zungenlage (Ps >.2O). maseténca en reiación a la posición de ia iengua (Ps > 0.20). Diese Befunde mahnen zur Vorsicht bei der Festiegung der Estos resultados indican que hay que tener cauteia ai calificar ia "Ruheposition" der Zunge und deuten darauf hin. dass weitere posición "de reposo" déla lengua e indican que es necesario Studien zur Beziehung zwiaoheri Zungenposition und orofaziaien efectuar más estudios en cuanto a ia relación entre ia posición Schmerzen notwendig sind. de la lengua y los dolores orofaciales.

Journal of Orofacial Pain 297