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.

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.

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.

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.

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.

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.

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.

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.

Normalization reduces the spatial dependency of the jaw-stretch reflex activity in the human masseter muscle.

The jaw-stretch reflex is the short-latency response in the jaw-closing muscles after a sudden stretch. The hypothesis whether normalization of the jaw-stretch reflex amplitude with respect to prestimulus electromyographic (EMG) activity will make the amplitude more independent of the location of the electrodes over the masseter muscle was tested. A 5 x 6 electrode grid was used to record the jaw-stretch reflex from 25 sites over the right masseter muscle of 15 healthy men. The results showed that there was a significant site dependency of the prestimulus EMG activity and the reflex amplitude. High cross-correlation coefficients were found between the spatial distribution of mean prestimulus EMG activities and reflex amplitude. When the reflex amplitude was normalized with respect to the prestimulus EMG activity, no site dependency was found. In conclusion, normalization of the jaw-stretch reflex amplitude by the prestimulus EMG activity strongly reduces its spatial dependency.

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.

Two-year natural course of anterior disc displacement with reduction.

AIMS: To test if the disappearance of clicking associated with anterior disc displacement with reduction (ADDR) is related to a gradual loss of reducing capacity of the disc in the temporomandibular joint. MATERIALS: Twenty-five ADDR subjects without and 30 ADDR subjects with intermittent locking participated in this 2-year follow-up study. Clinical examinations and mandibular movement recordings were performed at baseline and after 1 and 2 years. If mandibular movement recordings no longer showed signs of an ADDR, magnetic resonance imaging (MRI) of the disc was carried out. RESULTS: Mandibular movement recordings showed the moment of disc reduction (MDR) to be stable over the observation period in the subjects without intermittent locking (P = .95). In the subjects with intermittent locking, MDR had shifted to a later mouth opening (P = .000). In seven of these subjects, clicking had totally disappeared, usually without symptoms of permanent locking. On the MRI scans of these subjects, the disc displacement was still present, but with no, or only a partial, reduction. CONCLUSION: Intermittent locking may be indicative of the development of a disc displacement without reduction. This loss is only rarely accompanied by symptoms of permanent locking.

Temporomandibular disorder patients' illness beliefs and self-efficacy related to bruxism.

AIMS: To examine temporomandibular disorder (TMD) patients' illness beliefs and self-efficacy in relation to bruxism, and to examine whether these beliefs are related to the severity of patients' self-perceived bruxing behavior. METHODS: A total of 504 TMD patients (75% women; mean age ± SD: 40.7 ± 14.6 years), referred to the TMD Clinic of the Academic Centre for Dentistry Amsterdam, completed a battery of questionnaires, of which one inquired about the frequency of oral parafunctional behaviors, including bruxism (clenching and grinding). Patients' illness beliefs were assessed with a question about the perceived causal relationship between bruxism and TMD pain; patients' self-efficacy was assessed with questions about the general possibility of reducing oral parafunctional behaviors and patients' own appraisal of their capability to accomplish this. RESULTS: Sleep bruxism or awake bruxism was attributed by 66.7% and 53.8% of the patients, respectively, as a cause of TMD pain; 89.9% believed that oral parafunctions could be reduced, and 92.5% believed themselves capable of doing so. The higher a patient's bruxism frequency, the more bruxism was believed to be the cause of TMD pain (Spearman's rho 0.77 and 0.71, P < .001) and the more pessimistic the self-efficacy beliefs were about the reducibility of oral parafunctions (Kruskal-Wallis ?2 = 19.91, df = 2, P < .001; and Kruskal-Wallis ?2 = 7.15, df = 2, P = .028). CONCLUSION: Most TMD patients believe in the harmfulness of bruxism and the possibility of reducing this behavior. Bruxism frequency is associated with illness beliefs and self-efficacy.

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.

Variability in the apnea-hypopnea index and its consequences for diagnosis and therapy evaluation.

BACKGROUND: The apnea-hypopnea index (AHI) is frequently used to recognize obstructive sleep apnea (OSA) and to evaluate therapy. OBJECTIVES: The aim of this study was to determine the AHI variability during a 10-week period, and to discuss its consequences for diagnosis and therapy evaluation. METHODS: Fifteen OSA patients (50.8 +/- 11.2 years) underwent four polysomnographic (PSG) recordings, with a mean interval between recordings of 3.3 weeks. RESULTS: No differences were found in the average AHI values of the four PSG recordings (p = 0.985). Nevertheless, pooling all data of the 15 participants yielded a smallest detectable difference for AHI of 12.8. Linear regression between the individual means and standard deviations (SDs) of AHI showed that participants with a higher AHI tended to have a higher SD (p < 0.044). CONCLUSIONS: These results suggest a considerable intra-individual variability in AHI recordings. Hence, a single-night recording can only recognize OSA when the AHI lies outside a cutoff band surrounding the AHI cutoff point. AHI variability should also be taken into account when evaluating OSA therapy. In this context, it should be noted that it is mainly the approach that we would like to convey to the reader and not the cutoff values per se.

Evaluation of the Research Diagnostic Criteria for Temporomandibular Disorders for the recognition of an anterior disc displacement with reduction.

The aim of this Focus Article is to review critically the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) for the recognition of an anterior disc displacement with reduction (ADDR) in the temporomandibular joint (TMJ). This evaluation is based upon the experience gained through the careful analysis of mandibular movement recordings of hundreds of patients and controls with or without an ADDR. Clinically, it is a challenge to discriminate between the two most prevalent internal derangements of the TMJ: ADDR and symptomatic hypermobility. It is due to the very nature of these derangements that they both show clicking on opening and closing (reciprocal clicking), making reciprocal clicking not a distinguishing feature between these disorders. However, there is a difference in timing of their opening and closing clicks. Unfortunately, it is not feasible to use this difference in timing clinically to distinguish between the two internal derangements, because it is the amount of mouth opening at the time of the clicking which is clinically noted, not the condylar translation. Two other criteria proposed by the RDC/TMD for the recognition of an ADDR are the 5-mm difference in mouth opening at the time of the opening and closing clicks, and the detection of joint sounds on protrusion or laterotrusion in case of non?reciprocal clicking. These, however, run the risk of false-positive or negative results and therefore have no great diagnostic value. Instead, it is recommended that the elimination of clicking on protrusive opening and closing be examined in order to distinguish ADDRs from symptomatic hypermobility.

Time courses of myofascial temporomandibular disorder complaints during a 12-month follow-up period.

AIMS: To investigate the time courses of myofascial temporomandibular disorder (TMD) pain and mandibular function impairment (MFI), and to identify predictive factors associated with these time courses. METHODS: During a 12-month period following conservative TMD treatment, the time courses of myofascial TMD pain and pain-related disabilities were assessed by questionnaires. Ninety-six myofascial TMD patients participated, of whom 70 completed the study. Before treatment (baseline data), Characteristic Pain Intensity (CPI), MFI, parafunctional activities, and psychological status were assessed, and at completion of treatment and at 3, 6, 9, and 12 months, CPI and MFI were scored again. Individual time courses in scores were analyzed using linear growth modeling. RESULTS: Baseline values of CPI had a positive correlation with CPI during follow-up (P = .002), whereas the influences of reported parafunctions and of pain elsewhere on CPI scores were close to significance (P = .058 and .06, respectively). Patients with a low somatization score showed a further decline in CPI during follow-up (P = .027), whereas patients with a high score showed a gradual increase (P = .030). Baseline values of MFI were positively correlated with MFI scores during the follow-up period (P = .000). The influence of reported parafunctions on MFI was not significant (P = .174), but that of pain elsewhere was (P = .004). The trend for a further decline in MFI values during follow-up was close to significance (P = .063) for patients with low somatization scores. Patients with high somatization scores showed a significant increase in MFI values (P = .007). CONCLUSION: Baseline reports of pain and impairment, oral parafunctional activities, pain elsewhere in the body, and somatization are associated with the severity and time course of myofascial TMD complaints following treatment.

Ethnic background as a factor in temporomandibular disorder complaints.

AIMS: To examine the associations between the ethnic backgrounds of temporomandibular disorder (TMD) patients in the Netherlands and the level of TMD pain complaints and psychological/behavioral factors and whether these associations are influenced by socioeconomic factors. METHODS: A sample of 504 consecutive patients from a TMD clinic completed the Research Diagnostic Criteria for TMD (RDC/TMD) Axis II questionnaire (pain intensity, pain-related disability, somatization, depression, ethnic background, and socioeconomic status), an oral parafunctions questionnaire, and questions related to stress. Ethnic background was classified, following the method of Statistics Netherlands (CBS), using the country of birth from subject and both parents. This resulted in a classification into three subgroups: Native Dutch (ND; 69.6%), Non-Native Western (NNW; 14.8%), and Non-Native Non-Western (NNNW; 15.6%). Statistics used were chi-square, one- and two-way ANOVA, and Kruskall-Wallis tests; for post-hoc interpretation, standardized residual values, Bonferroni, and Mann-Whitney U tests were used. RESULTS: No differences in age or gender were found between the three ethnic groups, nor were there any differences in characteristic pain intensity or oral parafunctions. However, TMD patients from the NNNW subgroup had significantly higher scores on psychological factors, namely pain-related disability, disability days, somatization, depression, and stress. These patients had a lower incidence of employment, a lower level of education, and a lower income level than patients from the ND and NNW ethnic backgrounds. Analysis of variance showed no interaction effects between ethnic background and socioeconomic factors in relation to the psychological variables mentioned. CONCLUSION: Ethnic background of TMD patients in the Netherlands is associated with psychological factors, regardless of socioeconomic status, but not with TMD pain complaints or oral parafunctions.

Diagnostic accuracy of temporomandibular disorder pain tests: a multicenter study.

AIMS: To estimate the diagnostic accuracy of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) clinical examination and of the dynamic/static tests for the recognition of TMD pain. Since the diagnosis of TMD pain is especially complicated in persistent orofacial pain patients, the test outcomes in persistent TMD pain patients were contrasted to those in two control groups: a group of persistent dental pain patients and a group of pain-free subjects. METHODS: In 125 persistent TMD pain patients, 88 persistent dental pain patients, and 121 pain-free subjects, a blind and standardized clinical examination was performed. RESULTS: For the RDC/TMD, sensitivity (88%) was high and specificity was low (pain-free group: 71%; dental pain group: 45%). For the dynamic/static tests, sensitivity was 65% and specificities were 91% and 84%, respectively. Comparing the outcomes of the two examinations showed higher positive likelihood ratios for dynamic/static tests (P < .001), and lower negative likelihood ratios for the RDC/TMD examination (P < .01). CONCLUSION: For the confirmation of a suspicion of TMD pain, it is better to rely on positive dynamic/static tests. To confirm the absence of TMD pain, it is better to rely on a negative RDC/TMD examination.

The Dutch version of the Oral Health Impact Profile (OHIP-NL): Translation, reliability and construct validity.

BACKGROUND: The purpose of this study was to make a cross-culturally adapted, Dutch version of the Oral Health Impact Profile (OHIP), a 49-item questionnaire measuring oral health-related quality of life, and to examine its psychometric properties. METHODS: The original English version of the OHIP was translated into the Dutch language, following the guidelines for cross-cultural adaptation of health-related quality of life measures. The resulting OHIP-NL's psychometric properties were examined in a sample of 119 patients (68.9 % women; mean age = 57.1 +/- 12.2 yrs). They were referred to the clinic of Prosthodontics and Implantology with complaints concerning their partial or full dentures or other problems with missing teeth. To establish the reliability of the OHIP-NL, internal consistency and test-retest reliability (N = 41; 1 - 2 weeks interval) were examined, using Cronbach's alpha and intraclass correlation coefficients (ICC), respectively. Further, construct validity was established by calculating ANOVA. RESULTS: Internal consistency and test-retest reliability were excellent (Cronbach's alpha = 0.82 - 0.97; ICC = 0.78 - 0.90). In addition, all associations were significant and in the expected direction. IN CONCLUSION: the OHIP-NL can be considered a reliable and valid instrument to measure oral health-related quality of life.