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1.
J Oral Rehabil ; 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34811784

RESUMO

BACKGROUND: The influence of the stomatognatic system on human posture control has been investigated under static conditions, but the effects on dynamic balance have not yet been considered. OBJECTIVE: Investigating the influence of different functional stomatognatic activities (jaw clenching (JAW), tongue pressing (TON) and habitual jaw position (HAB)) on postural performance during a dynamic reactive balance task. METHODS: Forty-eight physically active and healthy adults were assigned to three groups differing in oral motor tasks (JAW, TON or HAB). Dynamic reactive balance was assessed by an oscillating platform which was externally perturbed in four directions. Performance was quantified by means of Lehr's damping ratio. Mean speeds of the selected anatomical regions (head, upper body, pelvis, knee and foot) were analyzed to determine significant performance differences. RESULTS: The groups differed significantly in balance performance in direction F (i.e. forwards acceleration of the platform). Post-hoc tests revealed that the JAW group had significantly better performance compared to both the HAB and TON groups. Better performance was associated with a decreased mean speed of the analyzed anatomical regions. CONCLUSION: JAW can improve dynamic reactive balance but the occurrence of positive effects seems to be task-specific and not general. TON seems not to have any observable effects on dynamic reactive balance performance, at least when evaluating it with an oscillating platform. JAW might be a valuable strategy which could possibly reduce the risk of falls in elderly people, however further investigations are still needed.

2.
J Oral Rehabil ; 48(4): 392-402, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33368502

RESUMO

BACKGROUND: Closing movements are among the jaw's basic physiological motor actions. During functional movements, the jaw changes position continually, which requires appropriate proprioception. However, the significance of the various proprioceptive receptors involved and how they interact is not yet fully clear. OBJECTIVES: This study's main objective was to test whether preventing intercuspation (IC) for 1 week would affect the precision of jaw-closing movements into IC and the functional space of habitual chewing movements (HCM). A secondary objective was to compare precision of jaw-closing movements into IC with the precision of movements into a target position (TP) far from IC. METHODS: Fourteen participants' HCM and jaw-closing movements into IC were recorded on two sessions (T1 and T2) 1 week apart. Between sessions, participants wore posterior bite plates to prevent IC. They also received a 10-minute training session at T1 to guide their jaw-closing movements into TP. The precision of the closing movements into IC and TP was analysed. For HCM, the vertical amplitude, lateral width and area of chewing cycles were evaluated. RESULTS: The precision of jaw movements into IC increased as the jaw gap decreased, but precision did not differ significantly between T1 and T2. For HCM, the vertical amplitude and area of chewing cycles increased significantly between T1 and T2. The precision of the closing trajectory into TP increased significantly during the training session. CONCLUSION: Our results confirm the excellent adaptability of the craniomandibular system, controlled by stringent motor programmes that are supported by continuous peripheral sensory input.


Assuntos
Mastigação , Movimento , Humanos , Arcada Osseodentária , Periodicidade
3.
J Oral Rehabil ; 47(7): 783-795, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32077514

RESUMO

BACKGROUND AND OBJECTIVE: The aim of this single-centre, two-arm, parallel-group, double-blinded, randomised controlled trial was to investigate the disputed specific effectiveness of acupuncture by comparing acupuncture on specific and non-specific points among patients with non-chronic, painful TMDs. METHODS: Following predefined eligibility criteria, 49 consecutive patients of both sexes were recruited to the study. All subjects were diagnosed with a non-chronic (Graded Chronic Pain Scale grade <3) painful TMD, as assessed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Patients were randomly assigned to group A (acupuncture on specific points) or group B (acupuncture on non-specific points) after the initial examination (T0). Both acupuncture treatment sessions were conducted by a trained dentist once a week for four weeks. The examination was repeated five weeks (T5) after T0 by one calibrated examiner who was unaware of the study groups. Characteristic pain intensity (CPI) was evaluated as the main outcome criterion and compared between times and treatment groups by means of non-parametric tests (significance level set at P = .05). Secondary outcomes comprised the maximum corrected active mouth-opening without pain (MAO); patients' expectations regarding acupuncture treatment and pain development; depressivity; and oral health-related quality of life (OHRQoL). RESULTS: A total of 41 patients (38 female) successfully completed the study (mean age: 40.17 ± 16.61). The two groups did not differ significantly at any time in terms of age and CPI. However, CPI was significantly (P < .05) lower at T5 than at T0 for both groups (29.66 and 30.35% lower in group A and group B, respectively). An increase in MAO was observed at T5 for both groups but was significant for group B only (P = .016). All patients had positive expectations of acupuncture therapy, and the two groups did not differ significantly at T5 with regard to the extent to which their expectations had been fulfilled by the treatment (P = .717). Comparison of T0 and T5 showed a statistically significant reduction of depressivity for group A (P = .0205), but no significant change for group B (P = .329). At T5, OHRQoL had improved significantly for both groups (group A, P = .018; group B, P < .001) compared with at T0. CONCLUSIONS: Acupuncture on both specific and non-specific points reduces the non-dysfunctional pain of TMD patients. The effect of acupuncture on painful TMD cannot be attributed to the specific point selection.


Assuntos
Terapia por Acupuntura , Dor Crônica , Transtornos da Articulação Temporomandibular , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Qualidade de Vida , Resultado do Tratamento , Adulto Jovem
4.
Acta Odontol Scand ; 74(6): 480-6, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27410169

RESUMO

OBJECTIVE: The purpose of this study was to compare the short-term effectiveness of three different types of immediate, non-pharmacological intervention for alleviation of the painful symptoms of temporomandibular disorders (TMD). MATERIAL AND METHODS: Thirty-six patients (mean age 41.6 ± 16.7 years, 25 females) diagnosed with non-dysfunctional painful TMD received counselling and subsequently were randomly allocated to three treatment groups: patients in Group A received prefabricated oral splints with water-filled elastic pads (Aqualizer(®)), those in Group B were provided with vacuum-formed co-polyester oral splints and those in Group C were given appointments to receive Michigan-type hard splints. Clinical examination was conducted, at baseline and after 2 weeks, by use of the RDC/TMD. Current pain intensity was determined by evaluation of graded chronic pain status (GCPS) on a numerical rating scale (NRS). Active maximum mouth opening without pain (AMMOP) was also measured. Paired sample t-tests and one-way analysis of variance with a significance level of p ≤ 0.05 were conducted. RESULTS: After 2 weeks, overall mean current pain was reduced by 41.95% (p < 0.001). Current pain reduction was significant for Group B (66.6%, p < 0.001) but not for Groups A (37.88%, p = 0.56) and C (22.29%, p = 0.26). After 2 weeks, current pain level for Group B was significantly lower than that for Group C (p = 0.041). Overall, there was a statistically significant increase of AMMOP (p = 0.01). CONCLUSION: All therapeutic options were pain-reducing. The results from this study suggest that cost-effective and time-effective intervention of counselling combined with use of a vacuum-formed splint is a favourable option for initial, short-term treatment of painful TMD.


Assuntos
Dor Facial/terapia , Mandíbula/fisiopatologia , Placas Oclusais , Transtornos da Articulação Temporomandibular/terapia , Adulto , Idoso , Dor Facial/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Transtornos da Articulação Temporomandibular/complicações , Adulto Jovem
5.
Front Psychol ; 7: 291, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27014116

RESUMO

Postural control is crucial for most tasks of daily living, delineating postural orientation and balance, with its main goal of fall prevention. Nevertheless, falls are common events, and have been associated with deficits in muscle strength and dynamic postural stability. Recent studies reported on improvements in rate of force development and static postural control evoked by jaw clenching activities, potentially induced by facilitation of human motor system excitability. However, there are no studies describing the effects on dynamic stability. The present study, therefore, aimed to investigate the effects of submaximum jaw clenching on recovery behavior from forward loss of balance. Participants were 12 healthy young adults, who were instructed to recover balance from a simulated forward fall by taking a single step while either biting at a submaximum force or keeping the mandible at rest. Bite forces were measured by means of hydrostatic splints, whereas a 3D motion capture system was used to analyze spatiotemporal parameters and joint angles, respectively. Additionally, dynamic stability was quantified by the extrapolated CoM concept, designed to determine postural stability in dynamic situations. Paired t-tests revealed that submaximum biting did not significantly influence recovery behavior with respect to any variable under investigation. Therefore, reductions in postural sway evoked by submaximum biting are obviously not transferable to balance recovery as it was assessed in the present study. It is suggested that these contradictions are the result of different motor demands associated with the abovementioned tasks. Furthermore, floor effects and the sample size might be discussed as potential reasons for the absence of significances. Notwithstanding this, the present study also revealed that bite forces under both conditions significantly increased from subjects' release to touchdown of the recovery limb. Clenching the jaw, hence, seems to be part of a common physiological repertoire used to improve motor performance.

6.
Eur J Oral Sci ; 123(6): 439-46, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26446049

RESUMO

The objective of this study was to investigate the mechanisms of physiological control of the craniomandibular system during force-controlled biting: in intercuspation, restricted by predetermined anatomic-geometrical conditions [i.e. biting in intercuspation (BIC)]; and on a hydrostatic system [i.e. auto-balanced static equilibrium of the mandible (BAL)], in which the mandible is balanced under unrestricted occlusal conditions. For 20 healthy subjects, the spatial positions of the condyles, the lower molars, and the incisal point were measured, and the electromyographic (EMG) activity of the musculus masseter and musculus temporalis anterior were recorded bilaterally, during force-controlled biting (50, 75, 100 N) on a hydrostatic device. The results were compared with those obtained during BIC. During BAL, the neuromuscular system stabilizes one condyle, so it behaves as a virtual fulcrum, and all available biomechanical degrees of freedom of the opposite side are used to achieve a bilaterally equal vertical distance between the upper and lower dental arches. The variability of the positions of the molars was significantly smaller than for the condyles. The EMG co-contraction ratios calculated for homonymous muscle regions revealed significant differences between BIC and BAL, specifically, greater symmetry during BAL with substantial asymmetry of approximately 25% remaining. In conclusion, the results revealed precise neuromuscular control of the position of the lower dental arch; this information might form the basis for interference-free tracking of the mandible in intercuspation under different conditions.


Assuntos
Mandíbula , Força de Mordida , Eletromiografia , Humanos , Músculo Masseter , Dente Molar , Contração Muscular , Músculo Temporal
7.
Front Psychol ; 6: 750, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26082747

RESUMO

Human motor control is based on complex sensorimotor processes. Recent research has shown that neuromuscular activity of the craniomandibular system (CMS) might affect human motor control. In particular, improvements in postural stability and muscle strength have been observed as a result of voluntary jaw clenching. Potential benefits of jaw aligning appliances on muscle strength and golf performance have also been described. These reports are highly contradictory, however, and the oral motor task performed is often unclear. The purpose of our study was, therefore, to investigate the effect of submaximum biting on golf performance via shot precision and shot length over three different distances. Participants were 14 male professional golfers - seven with sleep bruxism and seven without - randomly performing golf shots over 60m, 160m, or driving distance while either biting on an oral splint or biting on their teeth; habitual jaw position served as the control condition. Statistical analysis revealed that oral motor activity did not systematically affect golf performance in respect of shot precision or shot length for 60m, 160 m, or driving distance. These findings were reinforced by impact variables such as club head speed and ball speed, which were also not indicative of significant effects. The results thus showed that the strength improvements and stabilizing effects described previously are, apparently, not transferable to such coordination-demanding sports as golf. This could be due to the divergent motor demands associated with postural control and muscle strength on the one hand and the complex coordination of a golf swing on the other. Interestingly, subjects without sleep bruxism performed significantly better at the short distance (60 m) than those with bruxism. Because of the multifactorial etiology of parafunctional CMS activity, conclusions about the need for dental treatment to improve sports performance are, however, completely unwarranted.

8.
Int J Prosthodont ; 27(4): 383-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25010884

RESUMO

PURPOSE: The purpose of this study was to examine, on the basis of masticatory performance (MP), total muscle work (TMW), and range of movement (RoM), whether reduction of the profile of the cusps results in loss of the biomechanical effectiveness of chewing by healthy dentate patients. METHODS: Twenty healthy patients (10 female, mean age: 24.1 ± 1.2 years) chewed standardized silicone particles, performing 15 masticatory cycles. Three experimental conditions were investigated: chewing on (1) the natural dentition (ND), (2) splints with structured occlusal profiles simulating the patient's natural dentition (SS), and (3) splints with a plane surface (PS). The expectorated particles were analyzed by a validated scanning procedure. The size distribution of the particles was calculated with the Rosin-Rammler function and the mean particle sizes (X50) were determined for each experimental condition. The target variables of the experimental conditions were compared by repeated measures analysis of variance. RESULTS: X50 values calculated for MP differed significantly (P < .002) between PS and SS, and between ND and SS. Conversely, no significant differences (P > .05) were observed between SS and ND. Regarding muscle work the EMG activity of the masseter differed significantly (P < .001) between the left and right sides, with higher values for the right (chewing) side. No significant differences (P > .05) were observed for TMW and RoM under the three test conditions. CONCLUSIONS: The results confirm the biomechanical significance of structured occlusal surfaces during chewing of brittle test food by young dentate subjects.


Assuntos
Oclusão Dentária , Mastigação/fisiologia , Coroa do Dente/anatomia & histologia , Fenômenos Biomecânicos , Eletromiografia/métodos , Feminino , Humanos , Masculino , Mandíbula/fisiologia , Músculo Masseter/fisiologia , Placas Oclusais , Tamanho da Partícula , Amplitude de Movimento Articular/fisiologia , Músculo Temporal/fisiologia , Fatores de Tempo , Adulto Jovem
9.
Eur J Oral Sci ; 122(1): 49-56, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24215119

RESUMO

Jaw-closing movements are basic components of physiological motor actions precisely achieving intercuspation without significant interference. The main purpose of this study was to test the hypothesis that, despite an imperfect intercuspal position, the precision of jaw-closing movements fluctuates within the range of physiological closing movements indispensable for meeting intercuspation without significant interference. For 35 healthy subjects, condylar and incisal point positions for fast and slow jaw-closing, interrupted at different jaw gaps by the use of frontal occlusal plateaus, were compared with uninterrupted physiological jaw closing, with identical jaw gaps, using a telemetric system for measuring jaw position. Examiner-guided centric relation served as a clinically relevant reference position. For jaw gaps ≤4 mm, no significant horizontal or vertical displacement differences were observed for the incisal or condylar points among physiological, fast, and slow jaw-closing. However, the jaw positions under these three closing conditions differed significantly from guided centric relation for nearly all experimental jaw gaps. The findings provide evidence of stringent neuromuscular control of jaw-closing movements in the vicinity of intercuspation. These results might be of clinical relevance to occlusal intervention with different objectives.


Assuntos
Oclusão Dentária , Mandíbula/fisiologia , Adulto , Relação Central , Eletromiografia , Feminino , Humanos , Incisivo/anatomia & histologia , Masculino , Mandíbula/anatomia & histologia , Côndilo Mandibular/anatomia & histologia , Músculo Masseter/inervação , Músculo Masseter/fisiologia , Movimento , Contração Muscular/fisiologia , Junção Neuromuscular/fisiologia , Amplitude de Movimento Articular/fisiologia , Telemetria/instrumentação , Músculo Temporal/inervação , Músculo Temporal/fisiologia , Fatores de Tempo , Ultrassom/instrumentação
10.
Int J Comput Dent ; 16(3): 209-24, 2013.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-24364193

RESUMO

Increased resting electromyographic activity (EMG), reduced EMG during maximum voluntary clenching, and a shift to lower frequencies of the mean/median power frequency (MPF) of the EMG power spectrum have been reported for patients with temporomandibular disorder pain. It is unclear, however, whether these electrophysiological phenomena can be correlated with symptom improvement during the follow-up of myofascial pain patients in treatment. The objective of this study was to monitor the therapeutic effects of two different splint concepts (standard method and a complex splint procedure assisted by transcutaneous electrical nerve stimulation, TENS) for a period of 12 weeks, by use of clinical outcome criteria and EMG recordings. We tested the hypotheses that both measures evaluated will change in parallel during treatment and that the different splint concepts will result in no outcome differences between the variables studied. For two randomly selected groups, each containing 20 non-chronic myofascial pain patients, the clinical course after splint insertion was documented over a period of 12 weeks on the basis of pain and pain on palpation ratings, in parallel with EMG recording. Baseline values were monitored for matched healthy subjects. Although there was no correlation between the course of symptom improvement and significant changes in EMG data, MPF differed significantly (p < 0.05) between healthy subjects and patients. The therapeutic effects of splints of different clinical complexity differed significantly (p < 0.05) between the patient groups, in favor of the complex oral appliances, and substantial (p < 0.001) but temporary pain relief was achieved by additional TENS. For non-chronic myofascial TMD pain patients treated with splints, the course of symptom improvement is not paralleled by significant changes in EMG data. MPF can, however, be used to distinguish between healthy subjects and patients. Splints of different clinical complexity differ in their therapeutic effects in non-chronic myofascial TMD patients, and substantial temporarily limited pain relief can be achieved by additional muscle stimulation by TENS.


Assuntos
Eletromiografia/métodos , Placas Oclusais/classificação , Síndrome da Disfunção da Articulação Temporomandibular/terapia , Adulto , Estudos de Casos e Controles , Dor Facial/fisiopatologia , Feminino , Seguimentos , Humanos , Registro da Relação Maxilomandibular , Masculino , Músculo Masseter/fisiopatologia , Contração Muscular/fisiologia , Desenho de Aparelho Ortodôntico , Medição da Dor , Palpação , Músculo Temporal/fisiopatologia , Síndrome da Disfunção da Articulação Temporomandibular/fisiopatologia , Estimulação Elétrica Nervosa Transcutânea/métodos , Resultado do Tratamento
11.
Int J Comput Dent ; 16(3): 225-39, 2013.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-24364194

RESUMO

The fourth part of this literature review on the clinical relevance of surface electromyography (EMG) of the masticatory muscles summarizes the results of clinical studies in patients with temporomandibular disorders (TMD), preferably randomized controlled trials, examining the impact of changes to the dynamic occlusion or the effects of occlusal splints and other treatment measures on electromyographic activity. Surface electromyography is a useful tool for neuromuscular functional analysis in the field of dentistry. In combination with a thorough history and detailed clinical examination, it is able to provide objective, documentable, valid and reproducible information about the individual functional status of the masticatory muscles if the user strictly adheres to the specific guidelines.


Assuntos
Eletromiografia/métodos , Músculos da Mastigação/fisiopatologia , Placas Oclusais , Transtornos da Articulação Temporomandibular/terapia , Oclusão Dentária , Humanos , Junção Neuromuscular/fisiologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Transtornos da Articulação Temporomandibular/fisiopatologia
12.
Z Evid Fortbild Qual Gesundhwes ; 107(4-5): 297-301, 2013.
Artigo em Alemão | MEDLINE | ID: mdl-23916268

RESUMO

Myofascial masticatory muscle pain is the second most frequent pain-related complaint in the orofacial region. Like unspecific musculoskeletal pain in other body segments, masticatory muscle pain is characterised by a multifactorial aetiology. The aim of this article is to document the current knowledge about the therapy with oral splints. It is shown that in both the short and long term, oral appliances can achieve sufficient pain relief in the majority of patients. In chronic myofascial jaw pain associated with psychosocial impairment in patients, effectiveness of splint therapy is limited, though. Within an interdisciplinary pain management programme, additional involvement of a psychotherapist is essential.


Assuntos
Neuralgia Facial/terapia , Dor Facial/terapia , Músculos da Mastigação/fisiopatologia , Placas Oclusais , Fenômenos Biomecânicos/fisiologia , Neuralgia Facial/fisiopatologia , Dor Facial/etiologia , Dor Facial/fisiopatologia , Humanos , Nociceptores/fisiologia , Desenho de Aparelho Ortodôntico
13.
Z Evid Fortbild Qual Gesundhwes ; 107(4-5): 302-8, 2013.
Artigo em Alemão | MEDLINE | ID: mdl-23916269

RESUMO

Pharmacological interventions in temporomandibular joint (TMJ) pain differ from corresponding therapeutic interventions of jaw muscle (myofascial) pain. An actual systematic literature search lists and evaluates available articles on randomised controlled trials for treatment of arthralgia of the TMJ. On the basis of the few available trial reports, non-steroidal anti-inflammatory drugs (NSAIDs) seem to be effective, but side effects and drug interactions need to be considered. In relation to other therapeutic modalities, the rapidity of the onset of action of NSAIDs seems to be different, and the extension of side effects can be varied or reduced by changing the application route (oral versus topical). Palmitoylethanolamide (PEA) as dietary supplement for special medical purposes can apparently evoke positive therapeutic effects in TMJ arthralgia which need to be analysed in further studies.


Assuntos
Analgésicos/uso terapêutico , Síndrome da Disfunção da Articulação Temporomandibular/tratamento farmacológico , Administração Oral , Administração Tópica , Amidas , Anti-Inflamatórios/efeitos adversos , Anti-Inflamatórios/uso terapêutico , Anti-Inflamatórios não Esteroides/efeitos adversos , Anti-Inflamatórios não Esteroides/uso terapêutico , Terapia Combinada , Suplementos Nutricionais , Interações Medicamentosas , Endocanabinoides/efeitos adversos , Endocanabinoides/uso terapêutico , Etanolaminas/efeitos adversos , Etanolaminas/uso terapêutico , Humanos , Placas Oclusais , Medição da Dor/efeitos dos fármacos , Ácidos Palmíticos/efeitos adversos , Ácidos Palmíticos/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Síndrome da Disfunção da Articulação Temporomandibular/diagnóstico
14.
J Orofac Pain ; 27(1): 61-71, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23424721

RESUMO

AIMS: To test the hypothesis that jaw muscles and specific neck muscles, ie, levator scapulae, trapezius, sternocleidomastoideus, and splenius capitis, co-contract at the different submaximum bite forces usually generated during jaw clenching and tooth grinding, and for different bite force directions. METHODS: Bite-force transducers that measured all three spatial force components were incorporated in 11 healthy subjects. The test persons developed feedback-controlled submaximum bite forces in a variety of bite-force directions. The electromyographic (EMG) activity of the levator scapulae, splenius capitis, and trapezius muscles was recorded, at the level of the fifth cervical vertebra, by use of intramuscular wire electrodes. The activity of the sternocleidomastoideus and masseter muscles was recorded by surface electrodes. For normalization of the EMG data, maximum-effort tasks of the neck muscles were conducted in eight different loading directions by means of a special force-transducer system. Differences between neck-muscle activity during chewing, maximum biting in intercuspation, and the force-controlled motor tasks were compared with the baseline activity of the various muscles by one-way repeated-measures analysis of variance. RESULTS: The results confirmed the hypothesis. Co-contractions of the neck muscles in the range of 3% to 10% of maximum voluntary contraction were observed. Significant (P < .05) activity differences were recorded as a result of the different force levels and force directions exerted by the jaw muscles. Long-lasting action potential trains of single motor units triggered by jaw clenching tasks were also detected. CONCLUSION: The findings support the assumption of a relationship between jaw clenching and the neck muscle activity investigated. The low level of co-contraction activity, however, requires further study to elucidate possible pathophysiological interactions at the level of single motor units.


Assuntos
Músculos da Mastigação/fisiologia , Contração Muscular/fisiologia , Músculos do Pescoço/fisiologia , Junção Neuromuscular/fisiologia , Potenciais de Ação/fisiologia , Força de Mordida , Eletrodos Implantados , Eletromiografia/instrumentação , Retroalimentação , Feminino , Humanos , Masculino , Músculo Masseter/fisiologia , Mastigação/fisiologia , Neurônios Motores/fisiologia , Transdutores , Adulto Jovem
15.
Eur J Oral Sci ; 120(4): 326-34, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22813223

RESUMO

Bruxism may be involved in the aetiology of myofascial neck pain. The objective of this study was to test the hypothesis that anterior and posterior neck muscles co-contract during jaw clenching. Ten test subjects developed different feedback-controlled submaximum bite forces in a variety of bite-force directions by means of bite-force transducers. The electromyographic activity of the sternocleidomastoid and supra/infrahyoidal muscles, and of the semispinalis capitis, semispinalis cervicis, and multifidi muscles was recorded by use of surface electrodes and intramuscular wire electrodes, respectively. For normalization of electromyography data, maximum voluntary contraction tasks of the neck muscles were conducted in eight different loading directions. The results confirmed co-contraction of the neck muscles in the range of 2-14% of the maximum voluntary contraction at a bite force ranging from 50 to 300 N. Significant activity differences were observed as a result of the different force levels and force directions exerted by the jaw muscles. Long-lasting tonic activation of specific neck muscles triggered by the jaw-clenching tasks was also detected. These findings support the assumption of a relationship between jaw clenching and the activity of the neck muscles investigated. The low level of co-contraction activity, however, requires further study to elucidate possible pathophysiological interactions at the level of single motor units.


Assuntos
Força de Mordida , Bruxismo/fisiopatologia , Arcada Osseodentária/fisiologia , Mastigação/fisiologia , Contração Muscular/fisiologia , Músculos do Pescoço/fisiologia , Adulto , Análise de Variância , Fenômenos Biomecânicos , Eletromiografia/métodos , Feminino , Humanos , Masculino
16.
Clin Oral Investig ; 15(5): 737-47, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20585815

RESUMO

It is well established that subjects without molars have reduced ability to comminute foods. However, epidemiological studies have indicated that the masticatory system is able to functionally adapt to the absence of posterior teeth. This supports the shortened dental arch concept which, as a prosthetic option, recommends no replacement of missing molars. Biomechanical modeling, however, indicates that using more anterior teeth will result in a larger temporomandibular joint load per unit of bite force. In contrast, changing bite from incisor to molar position increases the maximum possible bite force and reduces joint loads. There have been few attempts, however, to determine realistic joint loads and corresponding muscular effort during generation of occlusal forces similar to those used during chewing with intact or shortened dental arches. Therefore, joint and cumulative muscle loads generated by vertical bite forces of submaximum magnitude moving from canine to molar region, were calculated. Calculations were based on intraoral measurement of the feedback-controlled resultant bite force, simultaneous electromyograms, individual geometrical data of the skull, lines of action, and physiological cross-sectional areas of all jaw muscles. Compared to premolar and canine biting, bilateral and unilateral molar bites reduced cumulative muscle and joint loads in a range from 14% to 33% and 25% to 53%, respectively. During unilateral molar bites, the ipsilateral joints and contralateral muscles were about 20% less loaded than the opposing ones. In conclusion, unilateral or bilateral molar biting at chewing-like force ranges caused the least muscle and joint loading.


Assuntos
Força de Mordida , Mandíbula/fisiologia , Músculos da Mastigação/fisiologia , Articulação Temporomandibular/fisiologia , Dente/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Dente Pré-Molar/fisiologia , Fenômenos Biomecânicos , Simulação por Computador , Dente Canino/fisiologia , Arco Dental/fisiologia , Eletromiografia , Retroalimentação Fisiológica/fisiologia , Humanos , Masculino , Músculo Masseter/fisiologia , Modelos Biológicos , Dente Molar/fisiologia , Força Muscular/fisiologia , Músculos do Pescoço/fisiologia , Músculos Pterigoides/fisiologia , Músculo Temporal/fisiologia , Perda de Dente/fisiopatologia , Suporte de Carga/fisiologia , Adulto Jovem
18.
Arch Oral Biol ; 53(12): 1119-28, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18675391

RESUMO

Temporomandibular joint and masticatory muscle forces generated during bilateral biting on an experimental device simulating a symmetrically balanced maximum intercuspation, are unknown. The basic motor control strategies during such tasks, executed either strictly controlled or developed rather habitually, are also quite unclear. The main goal of this study was to compare muscle and joint forces at various magnitudes of force under two experimental conditions: (1) generation of a bite force vector perpendicular to the maxillary occlusal plane, (2) development of a directionally unrestricted (quasi-habitual) bite force, both with identical magnitude. Additionally, the experimental results were evaluated on the basis of optimisation strategies displaying physiologically reasonable neuromuscular objectives for coordinated muscle contraction. In 10 normal subjects, the electric activities of all jaw muscles were recorded bilaterally. Intraoral force transfer and force measurement were achieved by a measuring device with one anterior and two posterior force transmission points. Prior to the experiments, the force transmission was balanced at a directionally unrestricted resultant bite force of 100N. Under visual feedback-control, the subjects generated resultant forces of 50, 100, 150, 200, 300, and 400N, respectively. Joint and muscle forces were calculated based on the electromyograms of all jaw muscles, lines of action, geometrical data of the skull, and physiological cross-sectional areas acquired from all subjects. To identify possible motor control strategies, various physiologically reasonable objective functions were applied. The results revealed significant differences in force patterns generated under the two experimental conditions. Directionally unrestricted biting created higher forces in nearly all muscles and in the jaw joints. Muscle forces normalised with the magnitude of the inherent resultant force, and the findings from the optimisation calculations indicate variable central control mechanisms under the two experimental conditions, both minimizing energy consumption.


Assuntos
Força de Mordida , Músculo Masseter/fisiologia , Mastigação/fisiologia , Contração Muscular/fisiologia , Articulação Temporomandibular/fisiologia , Adulto , Fenômenos Biomecânicos , Estudos Transversais , Eletromiografia , Humanos , Masculino
19.
Eur J Oral Sci ; 116(3): 223-8, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18471240

RESUMO

The goals of this study were to investigate whether (i) muscle activities are affected by different feedback strategies, (ii) the balancing behavior of the neuromuscular system is influenced by different force levels, and (iii) axial loading of the posterior teeth is a realistic biomechanical conception. In 10 healthy subjects, all jaw muscles were recorded bilaterally. Intra-oral force transfer and force measurement were achieved by using a measuring device simulating natural maximum intercuspation. Under visual feedback-control, the subjects generated pure vertical and directionally unrestricted force vectors with identical force magnitude at different force levels. The force transmission characteristics under experimental occlusion were investigated by calculating the reduction point (RP) of the resultant bite force. Directionally unrestricted clenching revealed a higher activation of the musculature than pure vertical clenching and was also characterized by a distinct anterior force component. Under both test conditions, the RP moved towards a posterior position with increasing clenching forces. The results indicate an essential recruitment difference of the jaw muscles between the two clenching conditions. Pure axial loading of teeth seems to be impeded by the anterior force component during bilateral clenching. The posterior movement of the RP might prevent overloading of the temporomandibular joints and anterior teeth.


Assuntos
Força de Mordida , Mastigação/fisiologia , Músculos da Mastigação/fisiologia , Articulação Temporomandibular/fisiologia , Adulto , Análise de Variância , Fenômenos Biomecânicos , Análise do Estresse Dentário , Eletrodos , Eletromiografia , Humanos , Masculino , Neurônios Motores/fisiologia , Contração Muscular , Músculos do Pescoço/fisiologia , Recrutamento Neurofisiológico/fisiologia , Processamento de Sinais Assistido por Computador , Transdutores
20.
Clin Oral Implants Res ; 18 Suppl 3: 127-37, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17594377

RESUMO

OBJECTIVES: The use of patient-based outcomes to measure therapeutic effectiveness is increasing, because a growing number of clinical scientists are attempting to evaluate the impact of therapy on the recipient. There are indications that patients suffering from temporomandibular disorders (TMDs) may also show a reduced oral health-related quality of life (OHQoL). It was the purpose of this paper to answer the question as to whether therapeutic interventions in TMD patients have a positive effect on their OHQoL. MATERIAL AND METHODS: A systematic electronic search (Ovid Medline 1966-2006; Science Citation Index 1945-2006) of the literature was carried out to identify pertinent articles of randomized and non-randomized clinical trials. Reports on retrospective and prospective studies that specifically focused on OHQoL changes in TMD patients as a consequence of therapeutic interventions were included. The reference lists of the identified articles were screened to find additional pertinent publications. RESULTS: The investigation yielded seven relevant contributions from Medline. A quantitative analysis of the seven identified articles was not possible. There was considerable heterogeneity among the investigations with regard to study design, patient characteristics, and provided therapy. Three of the identified articles reported about prospective controlled studies, of which one was an RCT. Four additional investigations were retrospective. According to the results of the only RCT, a 6-week course of the non-selective cyclooxygenase (COX) inhibitor naproxen may lead to slightly better OHQoL in patients with temporomandibular joint (TMJ) arthralgia than the selective COX-2 inhibitor celecoxib. The two other articles reporting of a controlled study showed that selective serotonine uptake inhibitors accompanied by psychological therapy improved OHQoL in individuals with TMJ arthralgia. In contrast, TMJ surgery did not improve OHQoL. CONCLUSION: It appears that all therapeutic interventions reported in the identified publications led to at least some improvement of OHQoL. The only exception were patients with multiple TMJ surgeries.


Assuntos
Saúde Bucal , Qualidade de Vida , Transtornos da Articulação Temporomandibular/terapia , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos , Resultado do Tratamento
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