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PubMed2006

Interocclusal appliances--indications and clinical routines in general dental practice in Sweden.

The aim of this study was to analyse what kind of interocclusal appliances that are used in general dental practice in Sweden, the indications for such treatment, to what extent a clinical status is recorded before treatment, as well as the routines for evaluation of treatment results. The study was a retrospective analysis of patient records from 320 adult patients who had been treated by general dental practitioners in the Public Dental Service in Sweden. For comparison a group of 88 consecutive patients who had received interocclusal appliance therapy at a specialist clinic was used. The most common indication for treatment with hard acrylic stabilisation appliances, as well as with soft appliances, was occlusal wear due to tooth grinding. The second most common indication for treatment with hard acrylic stabilisation appliances was pain from masticatory muscles, while the second most common indication for soft appliances was tension-type headache. Treatment with soft appliances was more often combined with other treatment modalities compared to treatment with hard acrylic stabilisation appliances. Large variations were found between the 3 general dental clinics and the specialist clinic in respect of treatment indications, combinations with other treatment modalities, recording of clinical findings, follow-ups and evaluation of treatment results. General conclusion should, however, be made with caution due to the risk of selection bias. From the results of this study it is obvious that treatment with soft appliances is common in general dental practice in Sweden, despite the lack of scientific support for their efficacy, as well as effectiveness, compared to hard acrylic stabilisation appliances. There is an obvious need for investigations of the decision-making processes among dentists when performing treatment with interocclusal appliances, as well as for randomised controlled studies concerning efficacy and effectiveness of soft appliances.

Adult↗
PubMed1988

Symptoms and signs of mandibular dysfunction in primary fibromyalgia syndrome (PSF) patients.

Primary fibromyalgia syndrome (PFS) is a form of nonarticular rheumatism characterized by muscular pain and stiffness, commonly located in the neck-, shoulder-, back-, and pelvic regions. The most common finding in patients with mandibular dysfunction (MD) is pain or tenderness of the masticatory muscles, but tender and painful neck and shoulder muscles are also often found in relation to jaw muscle affection. Complaints presented by patients suffering from musculoskeletal conditions may overlap one another. Indeed, there may be some common causative factors for these complaints. To test the hypothesis that some complaints by PFS patients could be explained by mandibular dysfunction, we have investigated the subjective symptoms and the clinical state of the stomatognathic system in eight patients suffering from PFS. According to the Helkimo anamnestic dysfunction index, six patients were classified as having severe signs of MD. The Helkimo clinical dysfunction index revealed severe or moderate dysfunction in all patients. Recurrent headaches was reported by half of the patients. In conclusion, the present study shows that PFS patients also may suffer from mandibular dysfunction. Thus, an examination of the function of the stomatognathic system would be an important part in the investigation to elucidate possible etiological factors behind the reported complaints by PFS patients. PFS may also be of etiological importance for mandibular dysfunction.

Adult↗
PubMed2005

Reliability of distraction vector transfer in unilateral vertical distraction of the mandibular ramus.

Mandibular distraction osteogenesis fails in correcting the skeletal deformities if the vector of distraction is incorrect. Lack of vector control is caused mainly by two factors: first, deficient vector planning and transfer, and, second, resistance of the masticatory muscles and the remaining soft tissue envelope toward elongation. To enhance predictable placement of intraoral distraction devices during surgery and thereby the treatment outcome, a method combining planning, simulation, and transfer was developed. The presurgical planning was based on frontal and lateral head films, and the planned position and orientation of the distraction device was applied on the stereolithographic model. This model was cut according to the planned osteotomy, and the distraction was simulated. The transfer procedure copied the planned and simulated position of the distraction device during surgery by use of an individual guiding splint. The guiding splint was fabricated on plaster models, and transferred to the stereolithographic model to reproduce the planned and simulated distraction treatment during surgery. The reliability of the vector-transfer method was evaluated cephalometrically in a homogenous group of 13 patients and their respective stereolithographic models in comparison with the planned, simulated, and transferred distraction vectors.

Adolescent↗
PubMed1996

The influence of cutaneous tissue afferents on masticatory pain-pressure thresholds.

Pain-pressure thresholds are routinely used in orofacial pain research to record tenderness in masticatory muscles. This method is employed to stimulate deep tissue afferents, which are thought to be at least partially responsible for pain in temporomandibular disorders. Like other psychophysical measurements, however, this technique must stimulate cutaneous tissues before stimulating deeper tissues. This study examined 39 asymptomatic volunteers to quantify the effect of cutaneous sensory afferents on pain-pressure thresholds. In a randomized, double-blind fashion, pain-pressure thresholds were recorded at four facial sites before and after subjects received intradermal local anesthetic or a dry needle stick. Pain-pressure thresholds were significantly elevated after local anesthetic (P < .0001), suggesting that cutaneous tissues contribute significantly to the pain-pressure threshold. The authors discuss potentially important roles of cutaneous tissues in the assessment of deeper tissues and offer two theories of how the skin may be an important link in the assessment of temporomandibular disorders.

Administration, Cutaneous↗
PubMed1985

The Herbst appliance--its biologic effects and clinical use.

The purpose of this article is to survey the Herbst bite-jumping method. An outline of appliance design and appliance construction is given. The effects of the treatment method on the dentofacial complex and on the masticatory system have been analyzed with the aid of dental casts, cephalometric roentgenograms, and electromyographic registrations from the masticatory muscles. The use and effectiveness of the Herbst appliance in the treatment of Class II malocclusions are exemplified by clinical cases, some of which were followed for 5 years after treatment. The Herbst appliance is most effective in the treatment of Class II malocclusions, provided it is used as indicated. Thus, the appliance must be limited to growing persons only. The treatment method should not be looked upon as a last resort to be used only when other treatment approaches have failed. Treatment prognosis is best in subjects with a brachyfacial growth pattern. Unfavorable growth, unstable occlusal conditions, and persisting oral habits after treatment are potential risk factors for occlusal relapses. As treatment with the Herbst appliance is performed during a relatively short period, the hard and soft tissues (teeth, bone, and musculature) would need some time for adaptation to the new mandibular position after the appliance is removed. Posttreatment retention as a routine with a removable functional appliance is therefore recommended.

Activator Appliances↗
PubMed1998

Oral splints: the crutches for temporomandibular disorders and bruxism?

Despite the extensive use of oral splints in the treatment of temporomandibular disorders (TMD) and bruxism, their mechanisms of action remain controversial Various hypotheses have been proposed to explain their apparent efficacy (i.e., true therapeutic value), including the repositioning of condyle and/or the articular disc, reduction in the electromyographic activity of the masticatory muscles, modification of the patient's "harmful" oral behavior, and changes in the patient's occlusion. Following a comprehensive review of the literature, it is concluded that any of these theories is either poor or inconsistent, while the issue of true efficacy for oral splints remains unsettled. However, the results of a controlled clinical trial lend support to the effectiveness (i.e., the patient's appreciation of the positive changes which are perceived to have occurred during the trial) of the stabilizing splint in the control of myofascial pain. In light of the data supporting their effectiveness but not their efficacy, oral splints should be used as an adjunct for pain management rather than a definitive treatment. For sleep bruxism, it is prudent to limit their use as a habit management aid and to prevent/limit dental damage potentially induced by the disorder. Future research should study the natural history and etiologies of TMD and bruxism, so that specific treatments for these disorders can be developed.

Behavior Therapy↗
PubMed2002

The influence of altered occlusal guidance on condylar displacement.

This study investigated mandibular displacement and masticatory muscle activity during clenching in lateral occlusal position in relation to the lateral occlusal pattern. Twenty healthy human subjects (mean = 26.5 years) volunteered for this study. Metallic occlusal overlays were fabricated for the lower working side canine to second molar and non-working side second molar in order to simulate a canine protected occlusion, group function occlusion and bilateral balanced occlusion (balancing contact). Three-dimensional displacements of the bilateral condyle and electromyography (EMG) activities in the bilateral masseter, anterior and posterior temporalis were recorded during maximal clenching. The experimental occlusal pattern was revealed to have statistically significant effects on both condylar displacement and EMG activity (P < 0.001 and P < 0.001, respectively). When compared to the simulated group function occlusion, the simulated canine protected occlusion and balancing contact caused statistically significant smaller superior displacements of the non-working side condyle, which suggests that they may result in reduced temporomandibular joint (TMJ) loading. Furthermore, the simulated canine protected occlusion was associated with the lowest EMG activity, which suggests that this occlusal pattern has the capacity to reduce the level of parafunctional activity.

Adult↗
PubMed2004

Parameters of an optimal physiological state of the masticatory system: the results of a survey of practitioners using computerized measurement devices.

While bioelectronic instruments have been available for nearly 30 years to assist dentists in day-to-day evaluations of patients' masticatory systems, little guidance has been published to support physiological norms or ideals. An electronic questionnaire was developed and administered to an international group of dentists familiar with the use of bioelectronic instrumentation. Respondents were asked to provide feedback on the norms or ideal parameters of jaw movement, masticatory muscle function with electromyography, and joint sounds through electrosonography that they use in guiding evaluation and treatment of patients with temporomandibular disorders, neuromuscular occlusion, and orthodontics. Surveys were collated to determine areas of consensus. Out of 150 surveys, 55 responses were received from dentists representing nine different countries. Sixty percent of the respondents reported treating more than 150 cases in the past five years using bioelectronic testing. While experience ranged from 2-30 years with different types of devices, average experience was longer with mandibular/jaw tracking (mean 15.3 years) and electromyography (mean 14.1 years) than with electrosonography (mean 7.0 years). Parameters proposed as norms or ideals for electromyographic rest and clench values, and mandibular tracking (velocity, freeway space, and trajectory to closure) were very consistent. Although a smaller number of respondents reported utilization of electrosonography, their criteria for data significance and tissue-type genesis of joint sounds were consistent. While the intra-patient variability may limit the diagnostic use of bioelectronic instruments, the current study demonstrates that through decades of experience, dentists have independently arrived at very consistent definitions of an ideal physiology that can be used to guide treatment.

Biomedical Engineering↗
PubMed2005

Excitatory GABAergic synaptic potentials in the mesencephalic trigeminal nucleus of adult rat in vitro.

The mesencephalic trigeminal nucleus (MesV) contains the somata of primary afferent neurons innervating masticatory muscle spindles and the periodontal membrane. MesV afferent somata are unique in receiving synaptic inputs. Intracellular recordings in coronal pontine slices from adult rats were made from MesV neurons identified by having Cs-sensitive inward rectification and pseudounipolar morphology. Stimuli near the MesV evoked either a cluster of action potentials superimposed on a postsynaptic potential (PSP) or an antidromic spike at resting membrane potential (RMP). Membrane hyperpolarization revealed that each cluster of action potentials consisted of an antidromic spike and a subsequent PSP. Evoked PSPs in slices and miniature postsynaptic currents (mPSCs) recorded using whole-cell patch in dissociated MesV neurons were resistant to glutamate antagonists and strychnine but were reversibly abolished by 40 microM bicuculline. Superfusion of 1-10 mM GABA decreased input resistance and depolarized the membrane. Reversal potentials for evoked PSPs and GABA-induced depolarizations were similar and close to that for mPSCs which matched the Cl- equilibrium potential. Thus activation of synapses on MesV somata evokes GABAergic PSPs that generate action potentials at RMP in the adult. These data also indicate that primary afferent MesV neurons can act as interneurons in the central control of mastication.

Action Potentials↗
PubMed1986

Oculomasticatory myorhythmia: a unique movement disorder occurring in Whipple's disease.

We describe two patients and a previously reported patient who acquired unique pendular vergence oscillations of the eyes and concurrent contractions of the masticatory muscles, i.e., oculomasticatory myorhythmia (OMM). The smooth disjunctive eye movements cycled with a frequency of 0.8 to 1.2 Hz. An analysis of peak velocities (15 to 200 degrees/sec) with respect to peak amplitudes (5 to 25 degrees) revealed dynamics characteristic of normal vergence movements. The pathological alterations resulting in pendular vergence oscillations implicate a separately functioning, physiologically normal vergence system within the brainstem. In addition to paralysis of vertical gaze, each patient also experienced progressive somnolence and intellectual deterioration. An intestinal biopsy in 1 patient established a diagnosis of Whipple's disease, which led to appropriate treatment and amelioration of the OMM. A pathological diagnosis of Whipple's disease of the central nervous system was made in the other 2 patients; results of an intestinal biopsy in one of these patients were normal. No patient had palatal myoclonus, and olivary pseudohypertrophy was not found in two autopsy examinations. Thus, OMM is a distinct movement disorder and has been recognized only in Whipple's disease. We conclude that patients with OMM should be treated presumptively for Whipple's disease of the central nervous system, even if a jejunal biopsy is normal.

Eye Movements↗
PubMed2002

Neuromuscular evaluation of post-orthodontic stability: an experimental protocol.

To prevent relapse after orthodontic treatment, retention is often considered indispensable. Soft tissues are thought to have a significant influence on dental movements. To quantify the influence of masticatory muscles on post-treatment relapse, and in an attempt to avoid unnecessary procedures, 2 male orthodontic patients (13 and 30 years old at debonding) were followed up. The patients completed 2 years of fixed orthodontic treatment and received no post-orthodontic retention. After 1 week and again after 6 months, alginate impressions of dental arches and a surface electromyographic (EMG) assessment of the masseter and temporalis muscles during maximum voluntary clenching were performed. The younger patient received surface EMG monitoring once a month for the first 6 months and at the 1-year follow-up appointment. Arch dimensions and the 3-dimensional inclination of the facial axis of the clinical crown (FACC) were measured using a computerized digitizer. Symmetry in muscular contraction was measured by the percentage overlapping coefficient (POC), and potential lateral displacing components were assessed by the torque coefficient (TC). At the 6-month follow-up, no clinical modifications were observed. Quantitative evaluation assessed that arch dimensions had changed slightly (up to 1 mm). While the adolescent patient had no modifications in FACC inclinations, the 30-year-old patient showed significant alterations (up to 18 degrees). In all examinations of the adolescent patient, POC was higher than 86% and TC was lower than 10%. In the adult, POC was inside the normal range, while all TCs were higher than 10.5%. The larger TC measured in the adult may explain the larger modifications in the 3-dimensional position of his dental crowns. In conclusion, a surface EMG assessment may help in the detection of patients who might need post-orthodontic retention.

Adolescent↗
PubMed1994

Pain responses to experimental chewing in myofascial pain patients.

Although patients with myofascial pain of the masticatory muscles often report that chewing exacerbates their pain, this has never been verified experimentally. In this study, pain was assessed before and after chewing in 20 asymptomatic subjects and in 61 patients with muscle pain. First, self-reports of pain were obtained with a checklist and on five-point category scales (CAT) at the screening visit. None of the asymptomatic subjects reported that mastication or other jaw movements caused pain. On the other hand, the majority of patients reported that movements were painful (67.2%, checklist; 78.7%, CAT). Afterward, pain intensity at rest and after chewing on wax for 3 min was reported on 100-mm Visual Analogue Scales (VAS). No asymptomatic subjects had pain before or after the chewing test, while about 50% of the patients reported an increase of pain after chewing. In this subgroup, mean pain intensity increased by 102.6%. However, mean pain intensity after chewing decreased by 56.6% in about 30% of the patient sample. These patients had significantly higher resting pain than the first subgroup. These data show that a short chewing test can exacerbate pain in most myofascial pain patients but has no effect in asymptomatic subjects. Surprisingly, the exercise decreased pain in an important subgroup of patients. These results suggest that two subgroups of myofascial pain patients may exist with opposite reactions to exercise. It remains to be seen if these reactions are due to two different pathologies or to the fact that the pre-exercise pain levels were significantly different in the two groups.

Adolescent↗
PubMed2004

Topical review: new insights into the pathology and diagnosis of disorders of the temporomandibular joint.

The collection of conditions affecting the temporomandibular joint (TMJ) and masticatory muscles, the so-called temporomandibular disorders, can be classified according to the Research Diagnostic Criteria for Temporomandibular Disorders. Of the 3 subgroups--muscle disorders (Group I); disc displacements (Group II); and arthralgia, arthritis, and arthrosis (Group III)--the muscle disorders are most frequently seen in community samples; Group II and Group III diagnoses are less prevalent. This may explain the relative scarcity of studies involving intracapsular TMJ disorders. In this review, new insights into the functional anatomy, imaging, and pathology of disorders of the TMJ are presented. Studies of TMJ dynamics may provide insight into the functional anatomy of the TMJ and thereby into the consequences of Group II and Group III disorders. The clinical use of imaging modalities such as computed tomography and magnetic resonance imaging for the TMJ and related structures remains controversial. Nevertheless, imaging is regularly used in the diagnosis of some Group II and Group III disorders. Magnetic resonance imaging may be of use not only for the visualization of disc displacements but also for the study of bone mineral density of the condyle. Cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha) play an important role in TMJ pathology. For example, IL-1beta, which has been associated with TMJ pain, hyperalgesia, and anterior bite opening, is mostly absent in the synovial fluid of healthy joints. Since both IL-1 and TNFalpha are involved in the development of chronic pain and joint destruction, they may be the targets for specific treatments. While the advances reviewed in this paper are significant, multidisciplinary efforts and formation of international research collaborations will be necessary to continue advancement in the understanding of TMJ pathology and diagnosis.

Arthralgia↗
PubMed2002

A 3-dimensional finite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process.

OBJECTIVE: The condylar region is one of the most frequent sites for mandibular fractures, with direct application of miniplates being the most commonly used open-fixation technique today. Yet, anatomic and biomechanical limitations continue to make this application technically challenging with a considerable complication rate. We sought to analyze such incongruencies with respect to the complex biomechanical behavior of the mandible. STUDY DESIGN: Individual human mandible geometry, the specific bone density distribution, and the position and orientation of the masticatory muscles were evaluated by performing computed tomography scans and a sequential dissection of the cadaver mandible. Three-dimensional finite-element analysis was performed for different fracture sites, osteosynthesis plates, and loading conditions. RESULTS: Osteosynthesis of fractures of the condylar neck with 1 or 2 miniplates of a diameter of 2.35 x 1.00 mm was found to be an insufficient fixation method. This also applies for plates (3.60 x 1.54 mm), according to Pape et al,(8) when used in singular fashion (high condylar neck fractures excepted). In cases of singular occlusal contacts in the molar region (particularly at the contralateral side of the fracture), the highest stress values inside the mandible and osteosynthetic devices could be observed. With even the static yield limit of titanium being exceeded in such cases, consecutive rapid failure of the miniplates becomes most likely when loading of the condylar region caused by bite forces cannot be prevented. CONCLUSION: We strongly recommend the use, whenever possible, of 2 plates in the manner described by Pape et al(8) for osteosynthesis of fractures of the condylar neck in combination with bicortically placed screws. The stiffness of a singular osteosynthesis plate made of titanium in a diametrical dimension of approximately 5.0 x 1.75 mm was found to be equivalent to the physiological bone stiffness in the investigated fracture sites. The actual stiffness of such a fixation plate is approximately 3 times higher than the stiffness of devices commonly in use.

Bite Force↗
PubMed2002

Temporomandibular disorders in 19-year-old Korean men.

PURPOSE: The purpose of this study was to determine the prevalence and the nature of the relationships between 3 temporomandibular joint disease (TMD) symptoms and symptoms of associated structures. MATERIALS AND METHODS: This study was designed to rule out the effect from the uneven composition of the samples on TMD symptoms. The samples were collected from subjects who were of the same age, gender, district, and race. Nineteen-year old men (n = 27,978) were selected and investigated by means of questionnaires and clinical examinations. The prevalence of each symptom was studied and tried to determine the effects of the TMD-associated signs on the TMD signs. The indices allocated to reflect the TMD signs and symptoms and the others were dichotomized for bivariate analysis. The predictor variables were headache, neck pain, referred pain, stress, past trauma history in the TMJ, past TMJ dislocation, bruxism, and clenching. The outcome variables were mouth opening limitation, TMJ pain on rest, and TMJ pain during function. RESULTS: The incidence of masticatory muscle stiffness was 17.8%; TMJ sounds, 14.3%; headache, 7.2%; neck pain, 13.5%; bruxism, 8.4%; and clenching, 9.9%. Stress occurred in 12.8%, past trauma history in 11%, and previous joint dislocation in 2.5%. The experience of dislocation in the TMJ was found to be the most important risk factor in terms of mouth opening limitation (odds ratio, 4.08, P <.0001), joint pain during function (odds ratio, 5.50, P <.0001), and joint pain in the rest state (odds ratio, 4.63, P <.0001). Referred pain and the experience of trauma in TMJ were the secondary risk factors in terms of joint pain and referred pain and the stress in terms of mouth opening limitation. Considering referred pain can be induced by TMD, stress may be more related to mouth opening limitation (odds ratio, 2.18, P <.0001), and the experience of trauma in TMJ may be more related to pain in the rest state (odds ratio, 2.56, P <.0001) and during function (odds ratio, 2.47, P <.0001). CONCLUSIONS: The prevalence of TMD signs and symptoms as determined by this examination was in accord with the findings in women or mixed samples of other workers. Prior experience of a dislocated disc was found to be the most risky factor in TMD. Stress was related to limitations of mouth opening, and the experience of trauma in the TMJ was found to be related to pain in the joint region. Bruxism may not be a direct risk factor in TMD, and the clenching habit found to be more harmful than bruxism.

Adult↗
PubMed2003

Association between nocturnal bruxism and gastroesophageal reflux.

STUDY OBJECTIVE: To examine the relationship between nocturnal bruxism and gastroesophageal reflux. DESIGN: Controlled descriptive study and double-blind, placebo-controlled, clinical study. SETTING: Portable pH monitoring, electromyography, and audio-video recordings were conducted during the night in the subjects' home. PARTICIPANTS: Ten patients with bruxism and 10 normal subjects were matched for height, weight, age, and sex. They did not have symptoms of gastroesophageal reflux disease. INTERVENTION: Medication with a proton pump inhibitor (ie, a gastric-acid-inhibiting drug). MEASUREMENTS AND RESULTS: The bruxism group showed a significantly higher frequency of nocturnal rhythmic masticatory muscle activity (RMMA) episodes (mean +/- SD: 6.7 +/- 2.2 times per hour) and a higher frequency and percentage of time of gastroesophageal reflux episodes with a pH less than 4.0 and 5.0 (0.5 +/- 0.9 and 3.6 +/- 1.6 times per hour and 1.3% +/- 2.5% and 7.4% +/- 12.6%, respectively) than the control group (RMMA episodes: 2.4 +/- 0.9 times per hour; gastroesophageal reflux episodes: 0.0 +/- 0.0 and 0.1 +/- 0.3 times per hour and 0.0% +/- 0.0% and 0.0% +/- 0.0%, respectively). In the bruxism group, 100% of the gastroesophageal reflux episodes with a pH less than 3.0 and 4.0 included both an RMMA episode and an electromyographic burst, the duration of which was approximately 0.5 to 1.0 seconds, probably representing swallowing of saliva. The majority of gastroesophageal reflux episodes with a pH of 4.0 to 5.0 also included both an RMMA episode and an electromyographic burst in the control and bruxism groups (100% +/- 0.0% vs 70.7% +/- 16.5%), again probably due to swallowing of saliva. The remaining minority of gastroesophageal reflux episodes with a pH of 4.0 to 5.0 contained only an electromyographic burst (swallowing of saliva). The frequency of RMMA episodes after the release of the medication from the proton pump inhibitor, which increased the gastric and esophageal pH, was significantly lower than that after administration of the placebo in the control and bruxism groups (1.0 +/- 0.6 vs 1.9 +/- 3.2 times per hour, and 3.7 +/- 1.9 vs. 6.0 +/- 2.2 times per hour, respectively). CONCLUSIONS: Nocturnal bruxism may be secondary to nocturnal gastroesophageal reflux, occurring via sleep arousal and often together with swallowing. The physiologic link between bruxism and the increase in salivation needs to be investigated.

2-Pyridinylmethylsulfinylbenzimidazoles↗