Biomedical subjects

M Naeije

Publications and source records attributed to M Naeije.

At least 19 recordsLinked to original sources

PubMed2003

Measurement of condylar motion: a plea for the use of the condylar kinematic centre.

In this study, a plea is given for the use of the kinematic centre in studies of the kinematics of the human temporomandibular condyle. The concept of the kinematic centre is based upon the assumption that the movements of the condyle-disc complex within the temporomandibular joint can reasonably well be described by those of a ball-shaped condyle-disc complex. The kinematic centre is then the centre of the sphere. Its movement traces have the advantage that they are smooth and have a good reproducibility between consecutive movements. Moreover, the open and close traces are just a few tenths of a millimetre apart and show no crossings. This makes the kinematic centre a suitable choice in order to avoid false-positive diagnoses in the study of internal derangements by means of condylar movement recordings. However, the kinematic centre has the disadvantage that the mandibular movements have to be recorded by rather complicated six degrees of freedom recording equipment and that the exploration algorithm for its location may sometimes have difficulties in finding the right location.

Biomechanical Phenomena↗

PubMed2003

Biomechanics of the human temporomandibular joint during chewing.

Experimental data on the loading of the human temporomandibular joint during chewing are scarce. Coincidence of the opening and closing chewing strokes of the condyles probably indicates compression in the joint during chewing. Using this indication, we studied the loading of the joint during chewing and chopping of a latex-packed food bolus on the left or right side of the mouth. Mandibular movements of ten healthy subjects were recorded. Distances traveled by the condylar kinematic centers were normalized with respect to the distances traveled during maximum opening. We judged coincidence of the opening and closing condylar movement traces without knowing their origin. When subjects chewed, the ipsilateral condyles traveled shorter distances than did the contralateral condyles. During chewing and chopping, all contralateral condyles showed a coincident movement pattern, while a significantly smaller number of ipsilateral condyles did. These results suggest that the ipsilateral joints were less heavily loaded during chewing and chopping than were the contralateral joints.

Adult↗

PubMed2002

Local kinematic and anthropometric factors related to the maximum mouth opening in healthy individuals.

The aim of the present study was to investigate the influence of local anthropometric (mandibular length and width) and kinematic (forward and downward condylar translation and angle of rotation) variables upon the maximum mouth opening (MMO). Thirty-five healthy individuals, 17 men and 18 women, mean age 23 years with a range from 18 to 31 years, performed six to eight maximal, symmetrical and pain-free open-close movements during a 20-s recording. Mandibular movements were recorded by means of the OKAS-3D jaw movement recording system. A stepwise regression analysis showed that differences in MMO are mainly explained by differences in the angle of rotation and in mandibular length (R2adj=91.5%). Including the downward and forward component of condylar translation into the regression model increased the explained variance with only 4.7%. A second stepwise analysis showed that the angle of rotation is positively related to the forward component of the condylar translation and negatively related to its downward component (R2adj=52.7%). In conclusion, differences in MMO between healthy individuals are, to a large extent, explained by differences in the angle of rotation and in mandibular length. In its turn, differences in the angle of rotation are related to differences in condylar translation.

Adolescent↗

PubMed2002

Is there a relationship between head posture and craniomandibular pain?

An often-suggested factor in the aetiology of craniomandibular disorders (CMD) is an anteroposition of the head. However, the results of clinical studies to the relationship between CMD and head posture are contradictory. Therefore, the first aim of this study was to determine differences in head posture between well-defined CMD pain patients with or without a painful cervical spine disorder and healthy controls. The second aim was to determine differences in head posture between myogenous and arthrogenous CMD pain patients and controls. Two hundred and fifty persons entered the study. From each person, a standardized oral history was taken and blind physical examinations of the masticatory system and of the neck were performed. The participants were only included into one of the subgroups when the presence or absence of their symptoms was confirmed by the results of the physical examination. Head posture was quantified using lateral photographs and a lateral radiograph of the head and the cervical spine. After correction for age and gender effects, no difference in head posture was found between any of the patient and non-patient groups (P > 0.27). Therefore, this study does not support the suggestion that painful craniomandibular disorders, with or without a painful cervical spine disorder, are related to head posture.

Adult↗

PubMed2001

Psychological distress in chronic craniomandibular and cervical spinal pain patients.

Recent studies to chronic pain have shown that the number of painful body areas is related to the level of psychological distress. Therefore, the first aim of this study was to analyse differences in level of psychological distress between craniomandibular pain patients with or without cervical spinal pain. In this analysis, the number of painful body areas below the cervical spine was also taken into account. The second aim was to determine psychological differences between subgroups of craniomandibular pain patients. In this study, 103 out of 250 persons with or without craniomandibular pain were included in the final analyses. Patients who suffered from both craniomandibular and cervical spinal pain showed higher levels of psychological distress, as measured with the Symptom Checklist 90 (SCL-90) than patients with local craniomandibular pain and persons without pain. Further, a positive relationship was found between the number of painful body areas below the cervical spine, as measured on a body drawing, and the SCL-90 scores. No psychological differences were found between myogenous and arthrogenous craniomandibular pain patients. In conclusion, chronic craniomandibular pain patients with a coexistent cervical spinal pain showed more psychological distress compared to patients with only a local craniomandibular pain and asymptomatic persons.

Adult↗

PubMed2001

Influence of periodontal receptors on the jaw-jerk reflex amplitude in man.

To study the role of periodontal mechanoreceptors in the modulation of the human jaw-jerk reflex, 60 reflexes were elicited in each of six healthy individuals under three different conditions: (a) with unilateral tooth support on the ipsilateral side; (b) with support on the contralateral side; and (c) with support and local anesthesia of the periodontal tissues on the ipsilateral side. During all conditions, background muscle activity and mandibular displacement were kept as constant as possible. Using on-surface EMG and the amplitude of the first peak of the biphasic jaw-jerk potential as the outcome variable, a condition-dependent reflex amplitude was found for the visually controlled right anterior temporalis muscle. Specifically, the 'ipsilateral support plus anesthesia' condition yielded higher amplitudes than the 'ipsilateral support' condition. Highest amplitudes were found for the 'contralateral support' condition. It was concluded that periodontal mechanoreceptors on the ipsilateral side have an inhibitory effect on the jaw-jerk reflex amplitude in the anterior temporalis muscle.

Adult↗

PubMed2001

Prevalence of cervical spinal pain in craniomandibular pain patients.

It has often been suggested that patients with a craniomandibular disorder (CMD) more often suffer from a cervical spine disorder (CSD) than persons without a CMD. However, in most studies no controlled, blind design was used, and conclusions were based on differing signs and symptoms. In this study, the recognition of CMD and CSD was based upon the presence of pain. The aim of this study was to determine the prevalence of cervical spinal pain in persons with or without craniomandibular pain, using a controlled, single-blind design. From 250 persons, a standardised oral history was taken, and a physical examination of the masticatory system and the neck was performed. Three classification models were used: one based on symptoms only; a second on signs only; and a third one based on a combination of symptoms and signs. The CMD patients were also subdivided in three subgroups: patients with mainly myogenous pain; mainly arthrogenous pain; and both myogenous and arthrogenous pain. Craniomandibular pain patients more often showed cervical spinal pain than persons without craniomandibular pain, independent of the classification model used. No difference in the prevalence of cervical spinal pain was found between the three subgroups of craniomandibular pain patients.

Adult↗

PubMed2001

Bruxism is mainly regulated centrally, not peripherally.

Bruxism is a controversial phenomenon. Both its definition and the diagnostic procedure contribute to the fact that the literature about the aetiology of this disorder is difficult to interpret. There is, however, consensus about the multifactorial nature of the aetiology. Besides peripheral (morphological) factors, central (pathophysiological and psychological) factors can be distinguished. In the past, morphological factors, like occlusal discrepancies and the anatomy of the bony structures of the orofacial region, have been considered the main causative factors for bruxism. Nowadays, these factors play only a small role, if any. Recent focus is more on the pathophysiological factors. For example, bruxism has been suggested to be part of a sleep arousal response. In addition, bruxism appears to be modulated by various neurotransmitters in the central nervous system. More specifically, disturbances in the central dopaminergic system have been linked to bruxism. Further, factors like smoking, alcohol, drugs, diseases and trauma may be involved in the bruxism aetiology. Psychological factors like stress and personality are frequently mentioned in relation to bruxism as well. However, research to these factors comes to equivocal results and needs further attention. Taken all evidence together, bruxism appears to be mainly regulated centrally, not peripherally.

Arousal↗

PubMed2001

A reliability study of clinical tooth wear measurements.

STATEMENT OF PROBLEM: Most studies examining tooth wear severity have been performed on dental casts. This indirect approach has limited applicability to dental practice because during the assessment of the casts, the identification of dentin exposure is difficult or even impossible. PURPOSE OF STUDY: The purpose of this study was to assess occlusal and incisal tooth wear clinically to determine the reliability of the assessment procedure and to establish the influence of selected relevant clinical variables (dental quadrant, tooth type, and severity of wear) on the reliability. MATERIAL AND METHODS: Forty-five volunteers (17 men, 28 women; mean age 33.7 +/- 10.7 years), 32 with temporomandibular disorders and 13 free from signs and symptoms of such disorders, were evaluated on 4 occasions. Two trained observers graded tooth wear at 2 different points in time with a 5-point ordinal scale developed for use in this study. The inter-rater and intra-rater reliability of the scale was expressed as Cohen's kappa. The influence of 2 clinical variables, dental quadrant and tooth type, on the values of kappa was tested with 1-way analysis of variance and post hoc Bonferroni tests. Probability levels of P< .05 were considered statistically significant. The influence of the final clinical variable, severity of wear, was assessed qualitatively. RESULTS: The overall values of the inter-rater and intra-rater reliability were substantial (kappa = 0.632 to 0.678). The clinical variable dental quadrant did not influence the kappa values, whereas the inter-rater reliability during the first session was better for incisors and canines than for premolars (1-way analysis of variance: F(3,23)=4.577, P=.012; post hoc Bonferroni tests: P=.030 and.036). Qualitative assessment of severity of wear indicated that the more advanced the tooth wear, the more reliably it could be graded. CONCLUSION: By means of the developed 5-point ordinal scale and within the limitations of this study, it was concluded that tooth wear can be assessed reliably in the clinical dental setting.

Adult↗

PubMed2001

The three-dimensional active envelope of jaw border movement and its determinants.

The sagittal and frontal active envelope of border movement is applied regularly as a clinical tool in functional examinations of the human masticatory system. In contrast, the three-dimensional movement area has hardly been examined. Furthermore, the determinants of this area are not established unambiguously. In the present study, the three-dimensional envelope of incisor movement was predicted with a three-dimensional mathematical model of the human masticatory system, which included the morphology of the system and the fine architecture of its muscles. With this model, the influence of the temporomandibular ligaments and the passive muscle tensions on the envelope were estimated. The predicted three-dimensional active envelope of border movements was limited in horizontal directions, predominantly by the temporomandibular ligaments. The passive tensions of the masticatory muscles influenced, although marginally, its vertical extension. It appeared unlikely that, in a normal situation, active muscle tensions (casu quo muscle reflexes) contribute to the shape of the envelope.

Computer Simulation↗

PubMed2001

Reports of SSRI-associated bruxism in the family physician's office.

AIMS: Recently, the use of selective serotonin reuptake inhibitors (SSRIs) has been associated with the occurrence or worsening of bruxism. The aim of this study was to obtain a first indication of the prevalence of SSRI-associated bruxism reported to family physicians, the main prescribers of SSRIs. METHODS: A questionnaire, with questions about prescription rate, already registered adverse reactions, and bruxism-related side effects of 4 different types of SSRIs, was sent to all family physicians in greater Amsterdam (n = 391). RESULTS: With a response rate of 42.5%, frequent observations of already registered side effects were found. In addition, 5 family physicians (3.2%) reported the occurrence of bruxism in relation to the use of SSRIs. CONCLUSION: The use of SSRIs might be associated with the occurrence of bruxism. A case report is provided that corroborates this suggestion.

Adult↗

PubMed2000

Clinical tests in distinguishing between persons with or without craniomandibular or cervical spinal pain complaints.

The recognition of a craniomandibular or cervical spinal pain is usually based upon the pain complaint of the patient, reported during an oral history, and the pain responses provoked in a clinical examination. Often used clinical tests are palpation, and function tests like dynamic/static tests or active movements. The relative importance of these tests for the recognition of the musculoskeletal pain is important. Therefore, it was the aim of the present study to determine which test, or combination of tests, best discriminates between persons with or without craniomandibular and/or cervical spinal pain complaints. Two hundred and fifty persons participated. From each person, a standardized oral history was taken. Then, in a randomized order and using a blind design, physical examinations of the craniomandibular system and of the neck were performed. Forward stepwise logistic regression analyses showed that the dynamic/static tests discriminated better between persons with and without pain complaints than the other tests did. In conclusion, in studies to the coexistence of craniomandibular and cervical spinal pain, it may be a good choice to base the recognition of these disorders on the pain complaints reported in the oral history which are verified by the pain response of the dynamic/static tests.

Adult↗

PubMed2000

Kinematics of the human mandible for different head postures.

The influence of head posture on movement paths of the incisal point (IP) and of the mandibular condyles during free open-close movements was studied. Ten persons, without craniomandibular or cervical spine disorders, participated in the study. Open close mandibular movements were recorded with the head in five postures, viz., natural head posture, forward head posture, military posture, and lateroflexion to the right and to the left side, using the Oral Kinesiologic Analysis System (OKAS-3D). This study showed that in a military head posture, the opening movement path of the incisal point is shifted anteriorly relative to the path in a natural head posture. In a forward head posture, the movement path is shifted posteriorly whereas during lateroflexion, it deviates to the side the head has moved to. Moreover, the intra-articular distance in the temporomandibular joint during closing is smaller with the head in military posture and greater in forward head posture, as compared to the natural head posture. During lateroflexion, the intra-articular distance on the ipsilateral side is smaller. The influence of head posture upon the kinematics of the mandible is probably a manifestation of differences in mandibular loading in the different head postures.

Adult↗

PubMed2000

Functional subdivision of the human masseter and temporalis muscles as shown by the condylar movement response to electrical muscle stimulation.

In previous studies from our laboratory, a functional subdivision of the human temporalis and masseter muscles was demonstrated by means of opto-electronic recordings of the lower incisal point movement responses to electrical muscle stimulation. In the present study, it was examined whether this subdivision was also reflected in different movement responses of the mandibular condyle. To that end, the condylar movement responses to unilateral stimulation of four masseter muscle parts and three temporalis muscle parts were studied in four different jaw positions. The kinematic centre was used for condylar reference point. For both the amplitude and the direction of the movement responses, the effects of stimulation location and jaw position were studied using multivariate ANOVA and contrast analyses. It was found that for both outcome variables, the functional subdivision of the masseter and temporalis muscles was also reflected in some, but not all, of the movement responses of the mandibular condyles. The deep masseter muscle part and the (anterior) temporalis muscle part responded similarly to electrical stimulation.

Adult↗

PubMed2000

[Treatment protocol for craniomandibular disorder 1. Diagnosis].

In two essays the treatment strategy of the department of Oral Function of the Academic Center of Dentistry Amsterdam for treating craniomandibular disorder (CMD) patients will be presented. This first essay starts with a short description of the symptomatology, classification and etiology of CMD. Then it is described how to diagnose a CMD with the use of a standardized diagnostic protocol. Some important aspects of the differential diagnosis of CMD are discussed. Furthermore it is discussed when a CMD-patient can be treated by the dentist or when referral to a CMD specialist or oral surgeon is necessary.

Craniomandibular Disorders↗

PubMed2000

[Treatment protocol for craniomandibular dysfunction 2. Treatment].

In two essays the treatment strategy of the department of Oral Function of the Academic Center of Dentistry Amsterdam for treating craniomandibular disorder (CMD) patients is described. In this second essay a description is given of several dental, physiotherapeutical and psychological treatment modalities for CMD. Then treatment strategies for the different categories of CMD are described. It is also indicated which aspects of the treatment strategy are based upon 'evidence based care' and which aspects are more based upon principles of 'common sense' and 'clinical prudence'.

Analgesics↗

PubMed2000

[Multidisciplinary diagnosis and treatment of craniomandibular disorders].

Treatment of craniomandibular disorders (CMD) requires a multidisciplinary approach. The CMD-team of the Academic Centre for Dentistry Amsterdam (ACTA) therefore consists not only of specialists in CMD and orofacial pain, but also of physiotherapists and a psychologist. Possible CMD-patients are referred to this team by the dentist-general practitioner, either directly or upon request of a family physician or a medical specialist; the many rules of such referrals are outlined in the article. The CMD-team regularly consults other disciplines for diagnosis and/or treatment of their patients. For instance, internal referrals are sometimes made to the departments of Oral radiology, Endontology, Periodontology, Orthodontics, or Oral and maxillofacial surgery. External referrals to, for example, a speech therapist or a medical specialist (e.g., a pain specialist) are arranged by the family physician upon request of the CMD-team.

Craniomandibular Disorders↗

PubMed2000

[Etiology of bruxism: morphological, pathophysiological and psychological factors].

Bruxism is a controversial phenomenon, but there is consensus about the multifactorial nature of the etiology. Besides peripheral (morphological) factors, central (pathophysiological and psychological) factors can be distinguished. In the past, morphological factors, like occlusal discrepancies and the anatomy of the bony structures of the orofacial region, have been considered the main causative factors for bruxism. Nowadays, these factors play only a minor role, if any. Recent focus is more on the pathophysiological factors. For example, bruxism has been suggested to be part of a sleep arousal response. In addition, bruxism appears to be modulated by various neurotransmitters in the central nervous system. More specifically, disturbances in the central dopaminergic system have been linked to bruxism. Further, factors like smoking, alcohol, drugs, diseases, and trauma may be involved in the bruxism etiology. Psychological factors like stress and personality are frequently mentioned in relation to bruxism as well, but research shows controversial results. Taken all evidence together, bruxism appears to be mainly regulated centrally, not peripherally.

Bruxism↗