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Biomedical subjects

F Lobbezoo

Publications and source records attributed to F Lobbezoo.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Role of the psychologist in the treatment of bruxism].

Although there is a controversy about the importance of psychological factors in the development, enhancement and perpetuation of bruxism and other parafunctional activities, the contribution of a psychologist in the treatment of the individual patient is recommended. This contribution consists of diagnostic examination and treatment, most often a short cognitive behavior modification therapy. Because bruxism is mostly examined and treated in relation to the complaints it might cause, especially CMD-complaints, diagnosis and treatment are mostly directed at both. For the diagnosis a questionnaire is used, including a psychological test, which is followed by one or more interviews. The treatment is directed at learning to recognize bruxism activities, to practice alternative behavior, and to learn to cope better with situations that may lead to an increase of bruxism.

Behavior Therapy↗
PubMed1999

Mandibular movements in response to electrical stimulation of superficial and deep parts of the human masseter muscle at different jaw positions.

Anatomical and electromyographical evidence suggests a compartmentalized function of the human jaw-closing muscles during both static and dynamic motor tasks. However, the voluntary nature of these tasks hampers unequivocal interpretation of this evidence, because it is impossible to activate voluntarily a single part of a muscle exclusively. Activation of discrete, localized regions can be accomplished with electrical stimulation. A previous study confirmed a functional subdivision of the temporalis muscle into at least three parts. Here, differences in the direction of the lower incisal-point (IP) movement in response to electrical stimulation of four different parts of the masseter muscle were examined in five healthy men. The deep masseter muscle and the anterior, middle, and posterior parts of the superficial masseter muscle were stimulated with monopolar wire electrodes in four different jaw positions (resting position; 50% maximum mouth opening; and 10-mm right and left lateral excursions, both with respect to resting position). Electrode-insertion depth was measured from magnetic resonance images. Movement responses to stimulation were recorded with the OKAS-3D jaw-movement analysis system. The variation in the direction of the IP movement in response to stimulation of parts of the masseter was partly explained by the effects of stimulus location and jaw position. The response to stimulation of the deep masseter was mainly laterovertically directed, whereas the response to stimulation of each of the superficial parts had a mainly anterovertical direction, the responses being most pronounced with the mandible in its resting position. These results provide further evidence for a functional subdivision of the masseter into a superficial part and a deep part, but not for a further subdivision of the superficial part into an anterior, middle, and posterior part.

Adult↗
PubMed1999

Sleep disorders and the dental patient: an overview.

This article is intended to briefly describe common sleep disorders of interest to the dental profession and to render general management guidelines. Topics include sleep-related bruxism, xerostomia, hypersalivation, gastroesophageal reflux, apnea, and the effect of orofacial pain on sleep quality. The term sleep-related is used instead of the term nocturnal because some of the activities described can occur with daytime sleep.

Bruxism↗
PubMed1999

The intra-articular distance within the TMJ during free and loaded closing movements.

Previous studies on free opening and closing movements of the mandible have demonstrated that the opening movement traces of the condylar kinematic center (i.e., the condylar point for which the protrusive and the opening movement traces coincide) lie closer to the articular eminence than the closing traces. This indicates the presence of an intra-articular distance within the joint during free closing. Since the mandible behaves like a class III biomechanical lever, a counteracting mechanical load on the mandible during closing will press the condyle-disc complex against the articular eminence. Therefore, in this study the hypothesis was tested that the difference between opening and closing movement traces of the kinematic center is reduced when the closing movements are counteracted by a mechanical load. From 10 healthy participants, 20-second movement recordings were obtained by a six-degrees-of-freedom opto-electronic jaw movement recording system (OKAS-3D) for three types of movements: (1) free opening and closing movements, (2) free opening and loaded closing movements (i.e., the participants closed against a small or high manually applied downward-directed force to the chin), and (3) gum chewing. Off-line, the opening and closing movement traces of the kinematic center were reconstructed, and the average difference between the traces (the intra-articular distance) was calculated. The average intraarticular distance was significantly smaller during loaded closing than during free closing, whereas no significant differences were found in the intra-articular distances between the loaded situations of low and high manual loading and contralateral chewing (ANOVA and post hoc Bonferroni multiple comparisons of means test, p<0.005). In conclusion, loading of the mandible during closing movements reduces the intra-articular distance within the temporomandibular joint.

Adult↗
PubMed1999

Variation in movement traces of the kinematic center of the temporomandibular joint.

AIM: The purpose of this study was to compare the variation in movement traces of the kinematic center of the temporomandibular joint with that of 4 nearby condylar reference points. METHODS: Jaw movement recordings were made with an optoelectronic jaw movement recording system. Four asymptomatic participants performed 14 to 18 open-close mandibular movements. The movements were performed with deliberate alterations of the rotation/translation ratio during opening. The kinematic center of the condyle and 4 nearby condylar points (the corner points of a square placed in the condylar sagittal plane, centered around the kinematic center, and with an edge length of 10 mm) were used as reference points. The standard deviations in the downward displacements at the halfway point in the mandibular opening of these reference points were calculated as a quantification of the variation in the movement tracings of these points. RESULTS: The movement traces of the kinematic center showed the smallest variation in comparison to the traces of the 4 nearby reference points (2-way analysis of variance and subsequent contrast analysis; P = 0.0026). CONCLUSION: In comparison to 4 nearby condylar reference points, the movement traces of the kinematic center show the lowest sensitivity to variations in the way mandibular movements are performed.

Adult↗
PubMed1997

The effect of catecholamine precursor L-dopa on sleep bruxism: a controlled clinical trial.

The putative role of the dopaminergic system in sleep bruxism (SB) was studied in a double-blind clinical trial by using low doses of short-term L-dopa in combination with benserazide. We recorded 10 patients with SB in our sleep laboratory for 3 consecutive nights. The first night was for habituation to the laboratory environment. During the second and the third nights, the patients received two doses of either L-dopa or a placebo in a crossover fashion: the first dose 1 h before bedtime and the second, 4 h after the first one. The order of administration was reversed in half the patients. The efficacy of L-dopa was analyzed by using multilevel models. L-Dopa resulted in a significant decrease in the average number of bruxism episodes per hour of sleep, as well as in a significant reduction in the average value of the root-mean-square (RMS) electromyography (EMG) level per bruxism burst. This indicates that L-dopa exerts an attenuating effect on SB. In addition, L-dopa caused a reduction in the variance in RMS values, which suggests that L-dopa normalizes the EMG activity patterns associated with SB.

Adult↗
PubMed1997

Motor activity in sleep bruxism with concomitant jaw muscle pain. A retrospective pilot study.

In a controlled polysomnographic (PSG) study that we recently performed in our laboratory, we noticed that some patients with a chief complaint of sleep bruxism reported concomitant non-myofascial pain in their masticatory muscles. To study the influence of such pain on the pattern of bruxism motor activity, we re-assessed the 2nd out of 2 consecutive PSG and masseter electromyographic (EMG) recordings of 7 bruxers without pain and 6 bruxers with concomitant jaw muscle pain. Among others, the selection of these patients was based on reports of current jaw muscle pain intensity, using 100-mm visual analogue scales. In our sample of bruxism patients with pain, levels of pain intensity did not differ significantly between bedtime and awakening in the morning. Although there were no significant differences between both subgroups of bruxers in the number of bruxism bursts per episode and the root-mean-squared EMG level per bruxism burst, bruxers with pain had 40% less bruxism episodes per hour of sleep. This suggests that non-myofascial jaw muscle pain decreases the number of initiations of bruxism episodes, but leaves their contents unaffected.

Adult↗
PubMed1997

Effects of the D2 receptor agonist bromocriptine on sleep bruxism: report of two single-patient clinical trials.

An altered dopamine receptor status has been associated with sleep bruxism. Evidence from a functional neuro-imaging study has implicated an abnormal side imbalance in striatal D2 receptor expression in its pathophysiology. To assess the significance of this finding, we studied the effects of short-term administration of the preferential dopamine D2 receptor agonist bromocriptine on sleep bruxism in a double-blind, placebo-controlled polysomnographic and neuro-imaging study with a single crossover design. Six otherwise healthy and drug-free patients with sleep bruxism were entered into the trial. One of the patients dropped out due to an intercurrent illness, while three others were discontinued from the study due to severe adverse reactions to bromocriptine. Because of the high frequency and intensity of the side-effects, the trial was interrupted. Two patients, however, completed the trial without any adverse reactions. Their outcome measures are presented as single-patient clinical trials. Following a two-week administration of bromocriptine, both patients showed a decrease in the number of bruxism episodes per hour of sleep of about 20% to 30% with respect to the placebo. WHile no significant differences between both conditions (i.e., placebo and bromocriptine) were found for the number of bruxism bursts per episode, significantly lower root-mean-squared EMG levels per bruxism burst occurred during bromocriptine use. In association with this polysomnographically established attenuation of sleep bruxism, bromocriptine afforded a decreased normal side distribution of striatal D2 receptor binding, as was evidenced by single-photon-emission computed tomography using the radioactive D2 receptor antagonist iodine-123-iodobenzamide. This study supports previous suggestions that the central dopaminergic system may be involved in the modulation of sleep bruxism. To see if the present findings apply across a population, investigators should use a peripheral D-2 antagonist to prevent side-effects.

Adult↗
PubMed1997

Do bruxism and temporomandibular disorders have a cause-and-effect relationship?

Controversy continues to exist over the putative role of bruxism in the etiology of temporomandibular disorders. A commonly held concept is that bruxism leads to signs and symptoms characteristic of one or more of the subdiagnoses of temporomandibular disorders, while another hypothesis suggests that bruxism is a temporomandibular disorder itself that sometimes coexists with other forms of temporomandibular disorders. Following a thorough review of the literature in this article, it is concluded that the relationship between bruxism and temporomandibular disorders is still unclear. Future research should examine longitudinal epidemiologic and clinical/experimental data to establish or refute a cause-and-effect relationship. In doing so, the existence of various sub-groups of temporomandibular disorders should be taken into account, and sleep-related bruxism should be discriminated from its daytime variant.

Bruxism↗
PubMed1997

Cigarette smoking as a risk factor or an exacerbating factor for restless legs syndrome and sleep bruxism.

Cigarette smoking has been associated with sleep disturbances. However, little is known about how smoking affects restless legs syndrome (RLS) and sleep bruxism, two movement disorders associated with sleep. From a nationwide survey of 2,019 Canadian adults, we estimated the prevalence of smoking to be 36%. Although there was no difference between smokers and nonsmokers for RLS prevalence, almost twice as many smokers (12%) as nonsmokers (7%) were aware of experiencing sleep bruxism. The estimated risk of a smoker suffering from RLS was nonsignificant. On the other hand, the risk of a smoker grinding his or her teeth was moderate (odds ratio = 1.9). Analysis of sleep laboratory findings revealed no differences in motor RLS and periodic leg movements in sleep (PLMS) indices between smoking and nonsmoking patients; after adjustment for age, there were no differences in sleep efficiency, latency, number of awakenings, or the arousal index for the RLS/PLMS patients. Among those suffering from bruxism, smokers had more tooth-grinding episodes than did nonsmokers (35.0 vs. 7.0; p = 0.056); none of the sleep variables differentiated sleep bruxism smokers from nonsmokers. It appears that cigarette smoking does not influence RLS/PLMS, whereas the risk that smoking and tooth grinding are concomitant is moderate. Smoking was not significantly associated with more motor activity in RLS/PLMS, but more grinding was noted in sleep bruxism.

Adult↗
PubMed1996

Effects of remote noxious stimulation on exteroceptive reflexes in human jaw-closing muscles.

Reflexes evoked by applying non-painful taps to an incisor tooth were recorded from the jaw closing masseter and temporal muscles of 21 human subjects. A series of inhibitory, excitatory, inhibitory and excitatory waves (the 'Q, R, S and T' waves of the post-stimulus electromyographic complex (PSEC)) occurred in full-wave rectified and averaged electromyograms. Conditioning by remote noxious stimulation (RNS; application of 3 degrees C water to a hand) usually produced increases in activity at the Q-R and S-T transitions of the PSEC (at mean latencies of 24 and 54 ms respectively), which resulted principally from a shortening of the inhibitory Q and S waves. Changes in the amplitudes of the excitatory R and T waves were also found. The effects of RNS were quantified by integrating records of the difference between conditioned and control PSECs. The RNS-induced effect on the entire PSEC was significantly (P < 0.01) greater when the reflexes were evoked by applying hard (7.4 mN.s) as opposed to soft (3.4 mN.s) taps to the tooth. However the ratio between the effects on the ST and QR segments did not differ significantly between these two intensities of tap stimuli. RNS-induced sensations of pain and increases in systemic arterial blood pressure were not correlated with the RNS-induced effects on the different segments of the PSEC. The results suggest that RNS may affect particularly those elements of the PSEC evoked by higher threshold afferents and that the effects are mediated by mechanisms acting directly at the brainstem level and are not secondary to pain or autonomic responses.

Adult↗
PubMed1996

Sensitivity of the jaw-jerk reflex in patients with myogenous temporomandibular disorder.

Changes in the activity of human jaw-elevator muscles related to the mandibular stretch (jaw-jerk) reflex could be involved in the aetiology of temporomandibular disorders (TMD). In order to investigate whether there are differences in the sensitivity of the jaw-jerk reflex between myogenous TMD patients (n = 10) and gender- and age-matched controls (n = 10), jaw-jerk reflexes were elicited under standardized conditions. By measuring the reflex with bipolar surface electromyography (EMG), reflex sensitivity was determined from relations between reflex amplitude and jaw displacement from the masseter and the anterior temporalis muscles. Reflex amplitude and background EMG activity were normalized with respect to the maximal voluntary contraction (MVC) to correct for differences in the thickness of soft tissues overlying the muscle or in electrode placement. In addition to normalization with respect to MVC, for the patients, normalization was also applied with respect to a MVC that was scaled by multiplying values by the ratio of the mean MVC of controls to the mean MVC of patients. At a constant level of background EMG activity, the reflex sensitivity can be determined from the slope (reflex gain) and x-intercept (reflex threshold) of the reflex amplitude-jaw displacement relation. No significant differences between patients and controls were found for the gain or threshold values of either the masseter or the anterior temporalis muscles with a univariate analysis of variance. It is concluded that jaw-jerk reflex sensitivity is not significantly changed in myogenous TMD patients. Therefore, the fusimotor system probably does not play a part in the perpetuating myogenous TMD.

Action Potentials↗
PubMed1996

Pain perception in idiopathic cervical dystonia (spasmodic torticollis).

Cervical spinal pain is frequently found in conjunction with idiopathic cervical dystonia (ICD), a focal dystonia characterized by sustained deviation of the head. Since the perception of noxious stimuli has never been studied in ICD, we performed a controlled study to obtain more insight into the psychophysics of dystonia-related muscle pain by evaluating pressure-induced pain levels. In nine ICD patients and five gender- and age-matched asymptomatic control subjects, pain-pressure thresholds (PPTs) were determined in the sternocleidomastoid and upper trapezius muscles, both at resting activity and at maximal voluntary contraction (MVC). The masseter muscles served as non-pathological control regions. To determine the accuracy of PPT values, pain intensity and unpleasantness were rated at threshold on 100-mm visual analogue scales. Four replication measurements were obtained. The data were analyzed by multilevel procedures. For all muscles under investigation, average PPTs of the ICD patients were about two times lower than those of the control subjects (P < 0.001-0.0005) and showed a smaller intra-subject variance. Further, average PPTs at MVC were about two times higher than those at resting activity (P < 0.005). These results provide psychophysical evidence to suggest that, at controlled levels of muscle contraction, the threshold of pain perception is decreased in ICD. In addition, ICD patients seem to be better able to establish their own PPTs than control subjects, which might be due to a different setting of the discriminative aspect of pain in ICD. Surprisingly, lower intensity and unpleasantness scores were found in ICD patients with coinciding painful and deviated sides than in ICD patients for whom the painful side was opposite to the deviated one (P < 0.05). This finding might be of clinical importance for defining functional disability and predicting treatment outcome.

Adult↗
PubMed1996

The influence of attentional factors on short- and long-latency jaw reflexes in man.

Reflexes evoked by applying non-painful taps to an incisor tooth were recorded bilaterally from the jaw-closing masseter and temporal muscles of 21 humans. A series of inhibitory, excitatory, inhibitory and excitatory waves (the Q, R, S and T waves) appeared in full-wave rectified and averaged post-stimulus electromyograms. These reflex responses were affected by the participants' levels of attention. When they undertook mental exercises in the form of arithmetic calculations, increases in electro-myographic activity were found around the transitions between the Q and R and the S and T waves. These increases involved principally a shortening of the inhibitory Q and S waves. There was no significant difference between the occurrence of these effects in the QR and ST segments. However, the effects were seen more commonly when the reflexes were evoked by hard (7.4 mN.s) as opposed to soft (3.4 mN.s) taps. It is concluded that, in man, attentional factors can modulate both short- and long-latency jaw reflexes, particularly when these are evoked by higher-threshold afferent nerves.

Adult↗
PubMed1996

Relationship between sleep, neck muscle activity, and pain in cervical dystonia.

OBJECTIVE: The interactions between sleep, neck muscle activity, and cervical spinal pain were examined in a controlled study with nine patients suffering from idiopathic cervical dystonia (ICD; also referred to as spasmodic torticollis), and nine gender- and age-matched controls. METHODS: From each participant, two all-night polysomnograms with additional electromyographic recordings from the sternocleidomastoid and upper trapezius muscles were obtained. The first night was for habituation to the laboratory environment; the second night for experimental data collection. Visual analogue scales were used to collect intensity and unpleasantness ratings of cervical spinal pain before and after the second sleep recording. RESULTS: None of the standard sleep variables showed statistically significant differences between average values of both groups of participants. However, a significantly larger variance in sleep latency was obtained for the ICD patients. In general, abnormal cervical muscle activity decreased immediately when lying down without the intention to go to sleep. Subsequently, abnormal muscle contractions were gradually abolished in all ICD patients during the transition from relaxed wakefulness to light NREM sleep. Following this transition phase, no more abnormal EMG activity was found in any of our patients. Finally, cervical spinal pain intensity and unpleasantness were reduced by about 50% overnight. CONCLUSIONS: Both supine position and sleep can be associated with an improvement of symptoms of ICD, and this disorder does not induce any sleep perturbations.

Adult↗
PubMed1996

Influence of the thickness of soft tissues overlying human masseter and temporalis muscles on the electromyographic maximal voluntary contraction level.

Skinfold measurements by means of calipers and the use of linear regression functions, representing relationships between maximal EMG activity and skinfold thickness, provide a simple and non-invasive procedure to diminish the influence of the thickness of the subcutaneous tissues overlying jaw-elevator muscles on electromyographic data of the maximal voluntary contraction (MVC) level. This method, which allows an improved comparison between different subject or muscle groups in terms of neuromuscular capacity, has been applied to MVC values from the masseter and the anterior temporal muscles (surface EMG) of 21 healthy males, 14 healthy females, and 14 females suffering from myogenous temporomandibular disorders (TMD). Non-corrected MVC values from both muscle groups were larger for the male controls than for the female controls. As the skinfold thickness was smaller for males than for females, these MVC levels did not differ significantly after correction for skinfold thickness. As the skinfold thickness was very similar for the female TMD patients and the controls, the correction method did not appreciably change the lower MVC values of the TMD patients.

Adult↗
PubMed1996

Striatal D2 receptor binding in sleep bruxism: a controlled study with iodine-123-iodobenzamide and single-photon-emission computed tomography.

The neurochemical mechanisms underlying sleep bruxism are little understood at present. However, recent pharmacologic evidence suggests that the central dopaminergic system may be involved in the pathophysiology of sleep bruxism. This possibility was further assessed by means of functional neuroimaging of dopamine D2 receptors with single-photon-emission computed tomography (SPECT). Ten controls and ten patients with polysomnographically confirmed sleep bruxism were injected intravenously with 185 MBq (5 mCi) iodine-123-iodobenzamide, a specific D2 receptor antagonist radioligand, and data acquisition was performed 90 min post-injection. Following image reconstruction, it was found that striatal D2 receptor binding potential (basal ganglia/background ratio) did not differ significantly between bruxism patients and controls. However, side-to-side differences between unilateral values of the striatal D2 binding potential ("highest side" values minus "lowest side" values) were significantly larger for the bruxism patients (p < 0.001, by two-independent-samples t test with pooled variances). It was concluded that an abnormal side imbalance in striatal D2 receptor expression can be associated with sleep bruxism. This reinforces the possibility that the central dopaminergic system plays a role in the pathophysiology of this disorder.

Adult↗