A Retrospective Study on Possible Predictive Factors for Long-term Temporomandibular Joint Degeneration and Impaired Mobility in Juvenile Arthritis Patients.

AIMS: To determine possible predictive factors for long-term temporomandibular joint (TMJ) degeneration and dysfunction in juvenile idiopathic arthritis (JIA) patients. METHODS: A total of 94 patients (77% female) who had received a JIA diagnosis in an outpatient rheumatology clinic from 1993 to 1994 at a mean ± standard deviation age of 8.3 ± 4.53 years were included in the study. At inclusion, TMJ status regarding condylar degeneration was assessed orthopantomographically and given a Rohlin and Petersson score of 0 or ≥ 1. The maximal mouth opening (MMO) was also measured. Data on possible predictors were gathered retrospectively from the consultation at intake: gender, age at JIA onset, JIA subtype, physical limitations (ie, a Steinbrocker classification score of 0 or ≥ 1), human leukocyte antigen-B27, and antinuclear and rheumatoid factors. Disease duration and medication type were also considered. Associations between all of these factors and long-term condylar degeneration and MMO were assessed by using single and multiple regression analyses. RESULTS: Long-term TMJ degeneration and smaller MMO were both associated with younger age at JIA onset (P = .01; P = .03) and longer disease duration (P = .05; P = .002). Moreover, MMO was negatively associated with physical limitations at intake (P = .04). CONCLUSION: Within the limitations of this retrospective study design, these results suggest that young JIA patients with early physical limitations and prolonged disease are at risk of long-term TMJ degeneration and impaired mobility.

Time-linked concurrence of sleep bruxism, periodic limb movements, and EEG arousals in sleep bruxers and healthy controls.

OBJECTIVE: Sleep bruxism (SB) and periodic limb movements during sleep (PLMS) may have a common underlying neurophysiologic mechanism, especially in relation to the occurrence of sleep-related electroencephalographic (EEG) arousals. To test this hypothesis, three research questions were assessed. First, it was assessed whether PLMS events occur more frequently in SB patients than in individuals without SB. Second, the question was put forward whether the combined presence of SB and PLMS events is more common than that of isolated SB or PLMS events in a group of SB patients. Third, as to further unravel the possible role of EEG arousals in the underlying neurophysiologic mechanism of SB and PLMS, it was assessed in a group of SB patients whether combined SB/PLMS events with associated EEG arousals are more common than those without associated EEG arousals. Positive answers to these questions could suggest a common neurophysiological basis for both movement disorders. MATERIALS AND METHODS: Seventeen SB patients and 11 healthy controls were polysomnographically studied. SB, PLMS, and EEG arousals were scored. An association was noted when the occurrence was within a 3-s association zone. RESULTS: The PLMS index was higher in SB patients than in healthy controls (P < 0.001). Within the group of SB patients, the combined SB/PLMS index was higher than the isolated SB index (P < 0.001) and the isolated PLMS index (P = 0.018). Similarly, the combined SB/PLMS index with EEG arousal was higher than the combined SB/PLMS index without EEG arousal in SB patients (P < 0.001). CONCLUSION: The results of this study indicate that SB, PLMS, and EEG arousals commonly concur during sleep in a time-linked manner. CLINICAL RELEVANCE: SB and PLMS probably have a common underlying neurophysiological mechanism.

Effects of occlusal stabilization splints on obstructive sleep apnea: a randomized controlled trial.

AIMS: To assess the influence of occlusal stabilization splints on sleep-related respiratory variables in obstructive sleep apnea (OSA) patients. METHODS: Ten OSA patients (47.3 ± 11.7 years of age) received a stabilization splint in the maxilla. All patients underwent three polysomnographic recordings with their splint in situ, and three recordings without their splint in situ, using a randomized crossover design. RESULTS: Repeated-measures ANOVAs did not yield statistically significant differences in the Apnea-Hypopnea Index (AHI) or in the Epworth Sleepiness Scale (ESS), neither between the three nights without the stabilization splint (AHI: F = 2.757, P = .090; ESS: F = 0.153, P = .860) nor between the nights with the splint in situ (AHI: F = 0.815, P = .458; ESS: F = 0.231, P = .796). However, independent ANOVAs revealed that the mean AHI of the three nights with the stabilization splint in situ (17.4 ± 7.0 events/hour) was significantly higher than that of the nights without the splint in situ (15.9 ± 6.4 events/hour) (F = 7.203, P = .025). The mean increase in AHI with the splint in situ was 1.4 ± 1.7 (95% confidence interval = -1.9-4.7). No difference in ESS was found when both conditions were compared (F = 1.000, P = .343). CONCLUSION: The use of an occlusal stabilization splint is associated with a risk of aggravation of OSA; however, the effect size was small, which reduces the clinical relevance of the study.

Why seek treatment for temporomandibular disorder pain complaints? A study based on semi-structured interviews.

AIMS: To identify potential predictors of self-reported sleep bruxism (SB) within children's family and school environments. METHODS: A Aims: To assess possible differences between care seekers and non-care seekers with temporomandibular disorder (TMD) pain complaints, by using semi-structured interviews. METHODS: Semi-structured interviews were held with 16 subjects who had TMD- pain complaints: 8 care seekers and 8 non-care seekers, matched for age, sex, pain intensity, and fear of movement. Subjects were selected from a previously held survey study, with their consent. The interviews were audiotaped, transcribed verbatim, and analyzed according to qualitative content analysis. RESULTS: From the analysis, seven themes differentiating care seekers from non-care seekers were identified: catastrophizing, pain management, assertiveness, critical attitude towards health care, confidence in medical care, recognition, and adequate referral. CONCLUSION: Aspects upon which care seekers differed from non-care seekers were mainly person-related characteristics. Next to these characteristics, it appeared that inadequate referrals may play a role in care seeking. The use of semi-structured interviews may further improve insights into processes that determine care seeking among people with TMD pain complaints.

Comorbidity negatively influences the outcomes of diagnostic tests for musculoskeletal pain in the orofacial region.

The aim of this study was to investigate whether diagnostic tests for musculoskeletal pain in the orofacial region [temporomandibular disorder (TMD) pain] are influenced by the presence of comorbid conditions, and to determine whether this influence decreases when the presence of "familiar pain" is used as outcome measure. In total, 117 patients (35 men, 82 women; 75 TMD-pain patients, 42 pain-free patients; mean age ± SD = 42.94 ± 14.17 years) were examined with palpation tests and dynamic/static tests. After each test, they were asked whether any pain was provoked and whether this pain response was familiar or not. For four clinical outcome measures (pain on palpation, familiar pain on palpation, pain on dynamic/static tests, and familiar pain on dynamic/static tests), multiple logistic regression analyses were performed with the presence of TMD pain as the primary predictor and regional (neck/shoulder) pain, widespread pain, depression, and somatization as comorbid factors. Pain on palpation was not associated with the primary predictor but with regional pain [P = 0.02, odds ratio (OR) = 4.59] and somatization (P = 0.011, OR = 8.47), whereas familiar pain on palpation was associated with the primary predictor (P = 0.003, OR = 5.23), but also with widespread pain (P = 0.001, OR = 2.02). Pain on dynamic/static tests was associated with the primary predictor (P < 0.001, OR = 11.08), but also with somatization (P = 0.037, OR = 4.5), whereas familiar pain on dynamic/static tests was only associated with the primary predictor (P < 0.001, OR = 32.37). In conclusion, diagnostic tests are negatively influenced by the presence of comorbidity. This influence decreases when the presence of familiar pain is used as outcome measure.

Is myofascial pain in temporomandibular disorder patients a manifestation of delayed-onset muscle soreness?

OBJECTIVE: In a study to the possible role of overuse of the jaw muscles in the pathogenesis of jaw muscle pain, we used a protocol involving concentric and eccentric muscle contractions to provoke a state of delayed-onset muscle soreness (DOMS) in the jaw muscles of healthy individuals. We tested whether the accompanying signs and symptoms would yield the temporary diagnosis of myofascial pain according to the research diagnostic criteria for temporomandibular disorders (RDC/TMD) in these individuals. METHODS: Forty persons (mean age±SD=27.7±7.5 y) performed six, 5-minute bouts of eccentric and concentric jaw muscle contractions. Before and immediately after the exercise, and 24 hours, 48 hours, and 1 week later, self-reported muscle fatigue and pain, pain-free maximum mouth opening, pressure-pain thresholds, and the number of painful jaw muscle palpation sites were recorded. RESULTS: Significant signs and symptoms of DOMS in the jaw muscles were found, which all had resolved after 1 week. In 31 (77.5%) of the participants, these signs and symptoms also gave rise to a temporary diagnosis of myofascial pain according to the RDC/TMD. CONCLUSIONS: The results of this study demonstrate that an experimental protocol involving concentric and eccentric muscle contractions can provoke DOMS in the jaw muscles and the temporary diagnosis of myofascial pain according to the RDC/TMD. The results observed strengthen the supposition that the myofascial pain in TMD patients may be a manifestation of DOMS in the jaw muscles.

Bruxism and associated factors among Dutch adolescents.

OBJECTIVES: To assess the prevalence rates of self-reported sleep bruxism and awake bruxism and their associations with several demographical, exogenous, and psychosocial factors among Dutch adolescents. METHODS: In a cross-sectional questionnaire survey, 4285 questionnaires were completed, with an about equal gender distribution and with ages ranging from 10 to 22 years. RESULTS: In the group of 4235 12- to 18-year-old adolescents, sleep bruxism had a reported prevalence of 14.8% and awake bruxism of 8.7%. Logistic regression analyses revealed that sleep bruxism was associated with female gender [OR = 1.49 (95% CI = 1.23-1.81)], pain or tense feeling in the jaws upon awakening in the morning [OR = 1.47 (95% CI = 1.17-1.86)], clicking joint sounds [OR = 1.31 (95% CI = 1.03-1.65)], stress [OR = 1.25 (95% CI = 1.00-1.55)], and depressive mood [OR = 1.35 (95% CI = 1.10-1.65)]. Awake bruxism was associated with orofacial pain [OR = 1.49 (95% CI = 1.16-1.91)], clicking joint sounds [OR = 1.50 (95% CI = 1.13-1.98)], scraping joint sounds [OR = 2.03 (95% CI = 1.21-3.37)], stress [OR = 1.36 (95% CI = 1.03-1.78)], depressive mood [OR = 1.82 (95% CI = 1.42-2.35)], and smoking [OR = 1.42 (95% CI = 1.06-1.89)]. CONCLUSIONS: Sleep bruxism and awake bruxism are common conditions among Dutch adolescents, with self-reported prevalence rates that are slightly higher than those derived from most large-scale studies on adults. Several predictor variables were found to be exclusively associated with either form of bruxism, corroborating the common suggestion that both circadian manifestations are, at least in part, different entities.

Effects of delayed-onset muscle soreness on masticatory function.

The aim was to clarify the effects of experimentally provoked delayed-onset muscle soreness (DOMS) in the jaw-closing muscles on subjective and objective measures of masticatory function. Twenty-one dentate female subjects, without pain-related signs and symptoms of temporomandibular disorders, participated. Delayed-onset muscle soreness was provoked with eccentric and concentric contractions of the jaw-closing muscles using a custom-made apparatus. At baseline, and 24 h and 1 wk after the exercises, data were gathered on the subjective measures of muscle fatigue, muscle pain, and masticatory chewing ability using visual analogue scale (VAS) scores, on the maximum voluntary bite force (MVBF), and on the food Mixing Ability Index (MAI). After 24 h, muscle fatigue and muscle pain had increased and the MAI had decreased. All had returned to baseline levels after 1 wk. There were no significant changes found in the chewing ability VAS scores and in the MVBF over time. After correction for its baseline value, the MAI after 24 h was found to be significantly related to the muscle pain after 24 h. In conclusion, DOMS in the jaw-closing muscles can cause a decrease in the objectively scored chewing ability, while the subjectively scored chewing ability remained the same.

Care seeking for orofacial pain.

AIMS: To determine the contribution of a wide range of factors to care-seeking behavior in orofacial pain patients, expressed as (A) decision to seek care and (B) number of health care practitioners visited. METHODS: Subjects with orofacial pain complaints were recruited in seven TMD clinics and from a nonclinical population sample. They received a questionnaire including a wide range of possible predictors. To study which predictive variables were associated with the decision to seek care and with the number of health care practitioners visited, multiple regression models were built. RESULTS: Two hundred three persons with orofacial pain participated in the study. Of these participants, 169 (140 females) had visited at least one health care practitioner (care seekers), while the other 34 persons (25 females) did not (non-care seekers). The decision to seek care was not only associated with the pain intensity (P < .05), but, in women, also with fear of jaw movements (P < .01): Women with more fear of jaw movements were more likely to seek care. Pain intensity and disability were not associated with the number of health care practitioners visited. Instead, the main predictors were catastrophizing (P = .004) and the use of painkillers (P = .008). CONCLUSIONS: Pain intensity and fear of jaw movements play an important role in the decision to seek care for orofacial pain. The continuous search for help is associated with catastrophizing and the use of painkillers.

Biomechanical modeling of open locks of the human temporomandibular joint.

BACKGROUND: Patients with hypermobility of the temporomandibular joint may have problems closing their mouth after opening widely. In the worst case, the mandibular condyles become trapped in front of the articular eminences and the jaw muscles cannot reposition them into the fossae (open lock). The difference in ease of closing the jaw between patients and non-patients is presently not well understood. METHODS: Wide opening and subsequent jaw closing were simulated with a biomechanical model in a forward dynamics approach. The effect of anterior slope angle and orientation of jaw-closing muscles on condylar travel was determined. FINDINGS: The mandibular condyles traveled anterior of the eminences and back into the fossae uneventfully with backwardly oriented jaw closers and eminences with a gentle anterior slope. However, combinations of relatively forward oriented jaw closers and a steep anterior slope caused the condyles to continue traveling anteriorly upon jaw-closing attempts, ending in an open lock position. INTERPRETATION: Our results indicate that for the masticatory system to reach an open lock, various unfavorable combinations of jaw-closer orientation and anterior slope angle exist within normal physiological ranges. These findings could be relevant for maxillofacial surgeons, both for the diagnostic process and for clinical decisions, regarding patients suffering from open locks.

Long-term follow-up of a randomized controlled trial of oral appliance therapy in obstructive sleep apnea.

BACKGROUND: Long-term trials are needed to capture information regarding the persistence of efficacy and loss to follow-up of both mandibular advancement device (MAD) therapy and continuous positive airway pressure (CPAP) therapy. OBJECTIVES: The aim of the study was to compare these treatment aspects between MAD and nasal CPAP (nCPAP) in a 1-year follow-up. METHODS: Forty-three mild/moderate obstructive sleep apnea patients (52.2 ± 9.6 years) with a mean apnea-hypopnea index (AHI) of 20.8 ± 9.9 events/h were randomly assigned to two parallel groups: MAD (n = 21) and nCPAP (n = 22). Four polysomnographic recordings were obtained: one before treatment, one for the short-term evaluation, and two recordings 6 and 12 months after the short-term evaluation. Excessive daytime sleepiness (EDS) was also evaluated at the polysomnographic recordings. RESULTS: The initially achieved improvements in the AHI remained stable over time within both groups (p = 0.650). In the nCPAP group, the AHI improved 4.1 events/h more than in the MAD group (p = 0.000). The EDS values showed a gradual improvement over time (p = 0.000), and these improvements were similar for both groups (p = 0.367). In the nCPAP group, more patients withdrew from treatment due to side effects than in the MAD group. CONCLUSIONS: The absence of significant long-term differences in EDS improvements between the MAD and the nCPAP groups with mild/moderate obstructive sleep apnea may indicate that the larger improvements in AHI values in the nCPAP group are not clinically relevant. Moreover, nCPAP patients may show more problems in accepting their treatment modality than MAD patients.

Risk factors for anterior disc displacement with reduction and intermittent locking in adolescents.

AIMS: To test the hypothesis that oral parafunctions and symptomatic temporomandibulair joint (TMJ) hypermobility are risk factors in adolescents for both anterior disc displacement with reduction (ADDR) and intermittent locking. METHODS: Participants were two hundred sixty 12- to 16-year-old adolescents (52.3% female) visiting a university clinic for regular dental care. ADDR and symptomatic TMJ hypermobility were diagnosed using a structured clinical examination. During the anamnesis, reports of intermittent locking and of several parafunctions were noted, eg, nocturnal tooth grinding, diurnal jaw clenching, gum chewing, nail biting, lip and/or cheek biting, and biting on objects. The adolescents' dentitions were examined for opposing matching tooth-wear facets as signs of tooth grinding. Risk factors for ADDR and intermittent locking were first assessed using univariate logistic regression and then entered into a stepwise backward multiple model. RESULTS: While in the multiple model, ADDR was weakly associated only with increasing age (P = .02, explained variance 8.1%), intermittent locking was weakly correlated to diurnal jaw clenching (P = .05, explained variance 27.3%). CONCLUSION: In adolescence, diurnal clenching may be a risk factor for intermittent locking while age may be a risk factor for ADDR. Symptomatic TMJ hypermobility seems to be unrelated to either ADDR or to intermittent locking.

Effect of chewing upon disc reduction in the temporomandibular joint.

AIMS: To test whether an intensive chewing exercise influences the moment of disc reduction in subjects with or without reports of intermittent locking of the jaw. METHODS: This experimental study included 15 subjects with a reducing anteriorly displaced disc (ADD) and with symptoms of intermittent locking and 15 subjects with a reducing ADD without such symptoms. The moment of disc reduction (MDR), quantified using mandibular movement recordings, was recorded at baseline, and after maximally 60 minutes of chewing. Thereafter, MDR was recorded again after 20 minutes of rest, and if necessary after 72 hours, in order to document return of MDR to baseline values. RESULTS: In subjects without intermittent locking, the MDR after chewing was not different from baseline (P = .25). However, in the subjects with intermittent locking, the MDR value had increased significantly after chewing (P = .008); two subjects showed a later moment of disc reduction, and four showed a temporary loss of disc reduction. CONCLUSION: While intensive chewing did not influence disc reduction in subjects without intermittent locking, it caused a delay or even hampered disc reduction in approximately half of the subjects reporting intermittent locking.

Oral appliance therapy versus nasal continuous positive airway pressure in obstructive sleep apnea: a randomized, placebo-controlled trial.

BACKGROUND: Previous randomized controlled trials have addressed the efficacy of mandibular advancement devices (MADs) in the treatment of obstructive sleep apnea (OSA). Their common control condition, nasal continuous positive airway pressure (nCPAP), was frequently found to be superior to MAD therapy. However, in most of these studies, only nCPAP was titrated objectively but not MAD. To enable an unbiased comparison between both treatment modalities, the MAD should be titrated objectively as well. OBJECTIVE: The aim of the present study was to compare the treatment effects of a titrated MAD with those of nCPAP and an intra-oral placebo device. METHODS: Sixty-four mild/moderate patients with obstructive sleep apnea (OSA; 52.0 ± 9.6 years) were randomly assigned to three parallel groups: MAD, nCPAP and placebo device. From all patients, two polysomnographic recordings were obtained at the hospital: one before treatment and one after approximately 6 months of treatment. RESULTS: The change in the apnea-hypopnea index (ΔAHI) between baseline and therapy evaluation differed significantly between the three therapy groups (ANCOVA; p = 0.000). No differences in the ΔAHI were found between the MAD and nCPAP therapy (p = 0.092), whereas the changes in AHI in these groups were significantly larger than those in the placebo group (p = 0.000 and 0.002, respectively). CONCLUSION: There is no clinically relevant difference between MAD and nCPAP in the treatment of mild/moderate OSA when both treatment modalities are titrated objectively.

The Tampa Scale for Kinesiophobia for Temporomandibular Disorders (TSK-TMD).

For musculoskeletal disorders like low back pain and fibromyalgia, evidence is growing for fear of movement to play an important role in the development of chronic pain. In temporomandibular disorder (TMD) patients, however, this construct has not received any attention yet. Therefore, in this paper, (1) a generally used instrument to measure fear of movement, the Dutch version of the Tampa Scale for Kinesiophobia (TSK), was adapted for its use in TMD patients (and translated for equivalence to English), (2) the psychometric properties of the Dutch version of the TSK-TMD were assessed, and (3) the association of various symptoms of TMD (i.e., pain, joint sounds, and limited jaw movements) with fear of movement was evaluated. In a sample of TMD patients (N=301), confirmatory factor analysis indicated that a two-factor model based on 12 items provides the best fit of the TSK-TMD, with activity avoidance and somatic focus as its subscales. This two-factor solution of the Dutch TSK-TMD has generally good reliability and convergent validity. Multiple regression analysis showed that TMD functional problems (i.e., temporomandibular joint sounds or a stuck/locked feeling) were more strongly associated with fear of movement than with pain. This finding leads to new perspectives regarding the interplay between musculoskeletal complaints, cognition, and avoidance behavior. The results provide a basis for use of the 12-item version for routine assessment of fear of movement in TMD patients, and for future clinical studies, for example, to the role of fear of movement in TMD-treatment success.

Provocation of delayed-onset muscle soreness in the human jaw-closing muscles.

Eccentric contractions of jaw-closing muscles are difficult to perform. This may explain why fatigue-inducing experiments performed so far suggest the jaw-closing muscles to be fatigue resistant. Aim of this study was to construct an apparatus that can impose intense eccentric contractions to the jaw-closing muscles, and to test the hypothesis that eccentric contractions can provoke symptoms of delayed-onset muscle soreness (DOMS) in these muscles. The provocation apparatus consists of two tungsten arms connected by a hinge axis on one end. Participants bite with their anterior teeth on biting plates located on the other end. Each time the experimenter gradually releases the compression force of the apparatus' rubber tubings, the mouth is forced open and the jaw-closing muscles perform an eccentric contraction. Six male participants performed eccentric contractions of their jaw-closing muscles in six sets of exercises, each lasting 5 min, and with 1 min of rest in between. Each set consisted of 60 open-close movements. Before and after the exercises, and after 24 h, 48 h, and 1 week, feelings of fatigue and pain, the maximum mouth opening without pain, muscles' tenderness to palpation and the maximum voluntary bite force were recorded. After 24 h and 48 h, the levels of fatigue and pain were elevated, the maximum mouth opening without pain was smaller, and five of the participants reported tenderness to palpation. The maximum voluntary bite force was also smaller after 24h. These findings indicate that this novel apparatus is successful in inducing DOMS in the jaw-closing muscles.

The reproducibility and responsiveness of a patient-specific approach: a new instrument in evaluation of treatment of temporomandibular disorders.

AIMS: To evaluate the choice of activities on the Patient Specific Approach (PSA) in a sample of temporomandibular disorder (TMD) patients and to determine the clinimetric properties of the visual analog scale (VAS) scores of the PSA, in terms of reproducibility and responsiveness. METHODS: At treatment start, TMD patients reported the PSA activity which represents the most important activity that is impaired due to their TMD complaints. The amount of hindrance during this activity was rated on a VAS. During two follow-up measurements, patients used the VAS to rate the amount of hindrance and appraised their overall complaints in terms of "much worsened," "slightly worsened," "remained stable," "slightly improved," or "much improved." To determine the reproducibility and responsiveness, an intraclass correlation coefficient and receiver operating characteristics-curve were then calculated. RESULTS: Of the 132 patients who fulfilled baseline measurements, 13% reported an activity that is not included in existing TMD-disability questionnaires. The reproducibility of the VAS scores of the 78 patients who reported that their complaints had "remained stable" at second measurement was good (intraclass correlation coefficient = 0.73). The responsiveness of the PSA was high, and the cutoff score for important improvement, where sensitivity (0.85) and specificity (0.84) were as much as possible the same, was 58%. CONCLUSION: The PSA for TMD patients is a new and easy-to-use tool in treatment evaluation. Moreover, the VAS score of the PSA has good reproducibility and responsiveness.

Differences in loading of the temporomandibular joint during opening and closing of the jaw.

Kinematics of the human masticatory system during opening and closing of the jaw have been reported widely. Evidence has been provided that the opening and closing movement of the jaw differ from one another. However, different approaches of movement registration yield divergent expectations with regard to a difference in loading of the temporomandibular joint between these movements. Because of these diverging expectations, it was hypothesized that joint loading is equal during opening and closing. This hypothesis was tested by predicting loading of the temporomandibular joint during an unloaded opening and closing movement of the jaw by means of a three-dimensional biomechanical model of the human masticatory system. Model predictions showed that the joint reaction forces were markedly higher during opening than during closing. The predicted opening trace of the centre of the mandibular condyle was located cranially of the closing trace, with a maximum difference between the traces of 0.45 mm. The hypothesis, postulating similarity of joint loading during unloaded opening and closing of the jaw, therefore, was rejected. Sensitivity analysis showed that the reported differences were not affected in a qualitative sense by muscular activation levels, the thickness of the cartilaginous layers within the temporomandibular joint or the gross morphology of the model. Our predictions indicate that the TMJ is loaded more heavily during unloaded jaw opening than during unloaded jaw closing.

Effects of an oral appliance with different mandibular protrusion positions at a constant vertical dimension on obstructive sleep apnea.

The aim of the study was to assess the influence of four mandibular protrusion positions, at a constant vertical dimension, on obstructive sleep apnea (OSA). Seventeen OSA patients (49.2 +/- 8.5 years) received an adjustable mandibular advancement device (MAD). The patients underwent four polysomnographic recordings with their MAD in situ at, in random order, 0%, 25%, 50%, and 75% of the maximum protrusion. The mean apnea-hypopnea index (AHI) values of the patients differed significantly between the protrusion positions (P < 0.000). The 25% protrusion position resulted in a significant reduction of the AHI with respect to the 0% position, while in the 50% and 75% positions, even lower AHI values were found. The number of side effects was larger starting at the 50% protrusion position. We therefore recommend coming to a weighted compromise between efficacy and side effects by starting a MAD treatment in the 50% protrusion position.