[Craniomandibular dysfunction?].
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Adult↗
Biomedical subjects
R S McCarroll
Publications and source records attributed to R S McCarroll.
Masticatory electromyographic activity in healthy young adults and myogenous craniomandibular disorder patients.
UNLABELLED: The electromyographic (EMG) activity of the masseter and the anterior temporalis muscles were compared between 60 healthy controls and 61 myogenous craniomandibular disorder (CMD) patients. Subjects were asked to clench at 10% and at 50% of their maximum voluntary clenching level. The effects of CMD, age and gender were statistically analysed with the use of the analysis of covariance. The correlations between EMG asymmetries and the lateral slide from the retruded contact position to the intercuspal position and the asymmetry in the number of post-canine tooth contacts between the left and the right side were investigated. The CMD patients showed lower masseter EMG activities than the controls, whereas the anterior temporalis EMG activity was not different between the two groups. The activity index, relating the anterior temporalis EMG activity to the activity of the masseter muscles, confirmed the presence of a relatively high temporalis activity in the CMD group. No significant differences were found in the EMG asymmetries between the controls and the CMD patients. Males showed higher masticatory EMG activities than females. These gender effects were significant for the anterior temporalis at the 10% and 50% level and for the masseter muscle at the 10% level. The anterior temporalis EMG activity declined with age. No age related effects were observed in the masseter EMG. The lateral slide was larger and more prevalent in the CMD group. A significant correlation between the lateral slide and the anterior temporalis EMG was found for the CMD group at the 10% level. No correlation was found between the EMG asymmetry and the asymmetries in post-canine tooth contacts. IN CONCLUSION: significant CMD, age and gender effects were observed in the masticatory EMG activities of a group of myogenous CMD patients and a control group.
Adolescent↗
Masticatory muscle activity in different jaw relations during submaximal clenching efforts.
The EMG activities of the masseter muscles and the anterior and posterior parts of the temporalis muscles were investigated in different vertical and sagittal jaw relations. Surface EMG recordings were made. Relative muscle activities were quantified by means of the Activity Index and the Asymmetry Index. Ten subjects with a healthy masticatory system were asked to clench at 10% and 50% of their maximum voluntary clenching level. Registrations were made during clenching in the intercuspal position, on a thin stabilization splint (SSP, 1-2 mm increase of vertical dimension at first molar), on a thick stabilization splint (3 mm thicker at the incisal edge relative to SSP), and on a protrusive re-positioning splint (3 mm protrusive to SSP). The masseter EMG amplitudes were the same for all the jaw positions investigated. However, at the 10% clenching level, the temporalis muscle activity decreased after the vertical dimension was raised and decreased further after the mandible was protrusively positioned (p less than 0.01). An independent function for the posterior and the anterior parts of the temporalis muscle was not found in any of the intermaxillary jaw relations investigated. At the 50% clenching level, a decrease in anterior temporalis muscle activity was observed only with the protrusive position in relation to the other three positions. Also at this level, the index relating the activity of the anterior to that of the posterior part of the temporalis muscle was not different between jaw positions. Raising the vertical dimension and protrusive positioning of the mandible decrease the activity of the temporalis muscles. This may be a factor related to the therapeutic effect of the stabilization splint in the treatment of craniomandibular disorder patients.
Adult↗
Diffuse sclerosing osteomyelitis of the mandible: a new concept of its etiology.
Diffuse sclerosing osteomyelitis of the mandible is a disease of unknown etiology. The clinical and radiographic findings suggest an infectious origin, but bacteriologic and histologic findings do not support this concept. Analysis of clinical symptoms, localization of the condition, and posttreatment findings in a group of 27 patients suggest a chronic tendoperiostitis due to muscular overuse as an etiologic factor in diffuse sclerosing osteomyelitis of the mandible. This hypothesis was supported by the initial results of muscle relaxation treatment in 13 of these patients.
Adolescent↗
Electromyographic activity of the human masticatory muscles during submaximal clenching in the inter-cuspal position.
The activity patterns of the masseter and the anterior temporal muscles were studied in twenty-one healthy male subjects while clenching at 10, 20, 30, 40 and 50% of the maximum clenching level. At low clenching levels the temporal muscle activity tended to dominate, at high levels the masseter muscle activity was stronger (P less than 0.001). The asymmetry in muscle activity also depended upon the clenching level (P less than 0.001), while at each level the masseter muscle asymmetry was greater than the temporal muscle asymmetry (P less than 0.05-P less than 0.025). By comparing the electromyographic activities of the left and right side within each subject it was found that the masseter muscle with the higher electromyographic activity tended to have the larger cross-sectional area (P less than 0.01) and at the 50% clenching level it tended to be on the side with the greater number of post-canine tooth contacts (P less than 0.001).
Adult↗
The immediate effect of splint-induced changes in jaw positioning on the asymmetry of submaximal masticatory muscle activity.
Maxillary full-arch splints in the retruded position (RP) and in a right lateral occlusion (1.0-1.5 mm to the right of the retruded contact position) were fabricated for ten subjects. Surface electromyography of the masseter and anterior temporal muscles was performed during submaximal clenching in order to investigate the immediate effects of the splints on the activity patterns of these muscles relative to the patterns found with the subjects occlusion in the inter-cuspal position. The splints in the RP were found to have no effect on the asymmetry of the activity of the masseter and the anterior temporal muscles, while the splints in a right lateral occlusion resulted in relative increases in right anterior temporal muscle activity (P less than 0.005).
Adult↗
Short-term effect of a stabilization splint on the asymmetry of submaximal masticatory muscle activity.
Ten healthy subjects continuously wore equilibrated maxillary full-arch stabilization splints in the retruded position for 7 days. The muscular activity balance of the masseter muscles during submaximal isometric clenching at 10% and 50% of the maximum voluntary contraction (MVC) did not change immediately on insertion of the splint, but was improved at the 50% level after 7 days (P less than 0.05). While the muscular balance of the anterior temporal muscles was not affected, either immediately on splint insertion, or after wearing it for 7 days, temporal muscle activity at 10% of the MVC was greater on the side to which the mandible moved from the retruded contact position (RCP) to the inter-cuspal position (ICP), both before (P less than 0.025) and after (P less than 0.01) wearing the splint. Splint removal after 7 days resulted in increased awareness of interferences in the ICP and increases in masseter muscle asymmetry (10%, P less than 0.025; 50%, P less than 0.05) when the electromyograms in the ICP after splint removal were compared with those on the stabilization splint before removal. After wearing the splint, the masseter muscle activity at the 10% level was greater on the side where premature contacts were present in the RCP (P less than 0.01). The use of masticatory muscle asymmetry indices in the evaluation of splint treatment for craniomandibular dysfunction is indicated since submaximal masticatory muscle activity is related to occlusal stability, premature contacts in the RCP and the direction of lateral slides from the RCP to the ICP.
Adaptation, Physiological↗
Balance in masticatory muscle activity during natural chewing and submaximal clenching.
The balance in the electromyographic (EMG) activities of the left and the right masseter and the left and right anterior temporal muscles during chewing and during submaximal clenching at 10% and 50% of the maximum voluntary contraction in the inter-cuspal position was investigated in twenty healthy adults. Muscular asymmetry patterns during chewing and clenching were positively correlated for both pairs of masticatory muscles investigated at the 50% level (P less than 0.01-P less than 0.001) and for the masseter muscles, also at the 10% level (P less than 0.01). Stronger correlations in muscular asymmetry were found for the masseter muscles and at the higher submaximal clenching level. In general, the masseter muscles displayed a greater degree of asymmetric activity than the anterior temporal muscles during both chewing and clenching (0.05 less than P less than 0.1-P less than 0.025). The average EMG amplitudes of both masseter or both anterior temporal muscles within each subject showed no correlation between clenching and chewing. The correlations between muscular asymmetries observed during static (clenching) and dynamic (chewing) conditions suggest that there are common factors influencing these activities.
Adult↗
The influence of tonic muscle activation on human jaw displacement tremor.
Jaw displacement tremor was investigated. Both tremor amplitude and tremor frequency were found to increase with increasing muscle activation. Co-contraction of jaw elevator and jaw depressor muscles was employed in order to vary muscle activation levels without the teeth being in occlusion. Reproducibility of tremor changes was statistically significant for each individual investigated. The relationship between tremor frequency and tremor amplitude, over the range of muscle activation investigated, varied per individual. It is hypothesized that the physiological basis for this inter-individual variation is differences in the development of jaw stiffness with increasing muscle activation between subjects. This explanation may be the basis, at least in part, for the clinical presence of objective jaw stiffness in one subject and its absence in another.
Humans↗
Mandibular border positions and their relationships with peripheral joint mobility.
Peripheral joint mobility was assessed in a group of fifty-one dental students using a modification of the Carter and Wilkinson Index. Mandibular border positions were measured both actively and passively with the aid of a millimetre ruler. The purpose of the investigation was to study possible relationships between generalized joint (hyper-)mobility and (hyper-)mobility of the temporomandibular joints. Only a few weak correlations were found between the mandibular border position measurements (active and passive mouth opening, active and passive, left and right, laterotrusions and active protrusion) and the peripheral joint mobility measurements. Differences between the sexes were illustrated in peripheral joint mobility with females showing a greater joint mobility than males, especially when only the passively measured joints were considered. The mandibular border positions were significantly correlated with each other (P less than 0.05-P less than 0.001) for the males, but few and then only weak relationships between these measurements could be found for the females in this group. The concept of temporomandibular joint 'end-feel' in relation to joint mobility is discussed.
Adult↗
Influence of chin tap force and bite force parameters on the duration of the electromyographic silent period.
Controversy exists as to whether chin tap force and bite force affect the duration of the electromyographic silent period following the jaw jerk reflex during isometric contraction of the elevator muscles of the mandible. This study demonstrates that statistical trends exist showing increased silent period duration for increased tap forces and decreased silent period duration with increased bite forces.
Adult↗
Relationship of electromyographic parameters in jaw dysfunction patients classified according to Helkimo's index.
Forty-two jaw pain-dysfunction syndrome patients (PDS) were divided into three groups depending on the severity of their condition using the Helkimo clinical dysfunction index. For both the left and right masseter and anterior temporal muscles three parameters of their electromyographic activity were measured, the silent period (SP), the root mean square value (RMS) and the mean power frequency (MPF). During the experiments the patients were instructed to clench as hard as possible in the intercuspal position. No statistically significant differences could be found between the values for any of the muscles measured between the different Helkimo clinical dysfunction groups. However, when the affected side was compared with the unaffected side in this patient material, statistically significant longer silent period durations and greater RMS values were found in the masseter muscles of the affected side group.
Adult↗