Introduction
The influence of aligners on the activity of the masticatory muscles is still controversial, especially regarding the behaviour associated with awake bruxism (AB).
Objective
To compare ...the frequency of AB behaviours between patients treated with aligners and fixed appliances.
Methods
The sample comprised 38 Class I patients (mean age 22.08 years), divided by simple randomisation into two groups: OA group; orthodontic aligners (n 19) and FA group; fixed appliance (n 19). The frequency of AB was investigated by the ecological momentary assessment using an online device (mentimeter), during 7 following days at different timepoints, before and after appliance placement and in the 2nd, 3rd, 4th and 6th months of orthodontic treatment. These variables were also evaluated: level of anxiety by the State‐Trait Anxiety Inventory, stress by the Perceived Stress Scale, catastrophising related to pain and degree of hypervigilance by the Pain Vigilance and Awareness Questionnaire, and the presence of facial pain evaluated by the DC/TMD.
Results
There was no difference between groups in the frequency of AB behaviours, with mean of 53.5% for group OA and 51.3% for FA. The most frequent behaviour was slightly touching the teeth, and in FA group, there was a significant reduction in this behaviour soon after appliance placement. The groups did not differ concerning the degree of anxiety, stress, catastrophising, hypervigilance and facial pain.
Conclusion
The orthodontic treatment performed with aligners or fixed appliances did not influence the frequency of AB during the 6 months of treatment.
Registry of Clinical Trials
(REBEC): RBR‐9zytwf.
Summary
There are relevant clinical overlaps between some of the painful temporomandibular disorders (TMD) and headache conditions that may hamper the diagnostic process and treatment. A ...non‐systematic search for studies on the relationship between TMD and headaches was carried out in the following databases: PubMed, Cochrane Library and Embase. Important pain mechanisms contributing to the close association and complex relationship between TMD and headache disorders are as follows: processes of peripheral and central sensitisation which take place in similar anatomical areas, the possible impairment of the descending modulatory pain pathways and the processes of referred pain. In addition, the clinical examination does not always provide distinguishing information to differentiate between headaches and TMD. So, considering the pathophysiology and the clinical presentation of some types of headache and myofascial TMD, such overlap can be considered not only a matter of comorbid relationship, but rather a question of disorders where the distinction lines are sometimes hard to identify. These concerns are certainly reflected in the current classification systems of both TMD and headache where the clinical consequences of diagnosis such as headache attributed to or associated with TMD are uncertain. There are several similarities in terms of therapeutic strategies used to manage myofascial TMD and headaches. Considering all these possible levels of interaction, we reinforce the recommendation for multidisciplinary approaches, by a team of oro‐facial pain specialists and a neurologist (headache specialist), to attain the most precise differential diagnosis and initiate the best and most efficient treatment.
This case-control study primarily compared the trigeminal nociceptive function, the intraoral somatosensory profile and possible structural nerve changes between diabetic peripheral neuropathy (DPN, ...n = 12) patients and healthy participants (n = 12). The nociceptive blink reflex (nBR) was recorded applying an electrical stimulation over the entry zone of the right supraorbital (V1R), infraorbital (V2R) and mental (V3R) and left infraorbital (V2L) nerves. The outcomes were: individual electrical sensory (I
) and pain thresholds (I
); root mean square (RMS), area-under-the-curve (AUC) and onset latencies of R2 component of the nBR. Furthermore, a standardized full battery of quantitative sensory testing (QST) and intraepidermal nerve fibre density (IENFD) or nerve fibre length density (NFLD) assessment were performed, respectively, on the distal leg and oral mucosa. As expected, all patients had altered somatosensory sensitivity and lower IENFD in the lower limb. DPN patients presented higher I
, I
, RMS and AUC values (p < 0.050), lower warm detection thresholds (WDT) (p = 0.004), higher occurrence of paradoxical heat sensation (PHS) (p = 0.040), and a lower intraoral NFLD (p = 0.048) than the healthy participants. In addition, the presence of any abnormal intraoral somatosensory finding was more frequent in the DPN patients when compared to the reference group (p = 0.013). Early signs of trigeminal nociceptive facilitation, intraoral somatosensory abnormalities and loss of intraoral neuronal tissue can be detected in DPN patients.
summary The aim of this study was to evaluate the maximum bite force in temporomandibular disorders (TMD) patients. Two hundred women were equally divided into four groups: myogenic TMD, articular ...TMD, mixed TMD and control. The maximum bite force was measured in the first molar area, on both sides, in two sessions, using an IDDK (Kratos) Model digital dynamometer, adapted to oral conditions. Three‐way anova, Tukey and Pearson correlation tests were used for the statistical analysis. The level of statistical significance was given when P ≤ 0·05. The maximal bite force values were significantly higher in the control group than in the experimental ones (P = 0·00), with no significant differences between sides. Higher values were obtained in the second session (P = 0·001). Indeed, moderate negative correlation was found between age and bite force, when articular, mixed groups and all groups together were evaluated. A moderate negative correlation was also detected between TMD severity and the maximal bite force values for myogenic, mixed and all groups together. Authors concluded that the presence of masticatory muscle pain and/or TMJ inflammation can play a role in maximum bite force. The mechanisms involved in this process, however, are not well understood and deserve further investigation.
Background
This study estimated the inter‐rater reliability and agreement of the somatosensory assessment performed at masseter and temporomandibular joint (TMJ) region in a group of healthy female ...and male participants.
Methods
Forty healthy participants (20 men and 20 women) were evaluated in two sessions by two different examiners. Cold detection threshold (CDT), warm detection threshold (WDT), thermal sensory limen (TSL), cold pain threshold (CPT), heat pain threshold (HPT), mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind‐up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying TMJ and masseter body. Mixed ANOVA, intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were applied to the data (α = 5%). Nonoverlapping 95% confidence intervals (95% CI) of ICCs were considered significantly different.
Results
The ICCs of 77% of all quantitative sensory testing (QST) measurements were considered fair to excellent (ICCs: 0.47–0.97), and WUR presented the lowest values. The reliability of WDT, TSL and HPT of masseter was significantly higher than TMJ, whereas the MDT reliability of TMJ was higher than masseter. In addition, the following combination of test/sites presented significantly lower ICCs for women: HPT, MDT of TMJ and MPT of both TMJ and masseter. Finally, the highest SEM values were presented for CPT and MPT.
Conclusion
The overall somatosensory assessment of the masticatory structures performed by two examiners can be considered sufficiently reliable to discriminate participants, except WUR. Possible site and sex influences on the reproducibility parameters should be taken into account for an appropriate interpretation and clinical application of QST.
Significance
The test site and participant's sex can significantly influence the relative reliability and agreement of quantitative sensory testing applied to musculoskeletal orofacial region, which affect the capacity to discriminate participants and to evaluate changes over time.
Summary
The impression of increased muscle hardness in painful muscles is commonly reported in the clinical practice but may be difficult to assess. Therefore, the aim of this review was to present ...and discuss relevant aspects regarding the assessment of muscle hardness and its association with myofascial temporomandibular disorder (TMD) pain. A non‐systematic search for studies of muscle hardness assessment in patients with pain‐related TMDs was carried out in PubMed, Cochrane Library, Embase and Google Scholar. Mechanical devices and ultrasound imaging (strain and shear wave elastography) have been consistently used to measure masticatory muscle hardness, although an undisputable reference standard is yet to be determined. Strain elastography has identified greater masseter hardness of the symptomatic side in patients with unilateral myofascial TMD pain when compared to the contralateral side and healthy controls (HC). Likewise, shear wave elastography has shown greater masseter elasticity modulus in patients with myofascial TMD pain when compared to HC, which may be an indication of muscle hardness. Although assessment bias could partly explain these preliminary findings, future randomised controlled trials are encouraged to investigate this relationship. This qualitative review indicates that the muscle hardness of masticatory muscles is still a rather unexplored field of investigation with a good potential to improve the assessment and potentially also the management of myofascial TMD pain. Nonetheless, the current evidence in favour of increased hardness in masticatory muscles in patients with myofascial TMD pain is weak, and the pathophysiological importance and clinical usefulness of such information remain unclear.
Background and Aims
Per‐ and polyfluoroalkyl substances (PFAS) are widespread and persistent pollutants that have been shown to have hepatotoxic effects in animal models. However, human evidence is ...scarce. We evaluated how prenatal exposure to PFAS associates with established serum biomarkers of liver injury and alterations in serum metabolome in children.
Approach and Results
We used data from 1,105 mothers and their children (median age, 8.2 years; interquartile range, 6.6‐9.1) from the European Human Early‐Life Exposome cohort (consisting of six existing population‐based birth cohorts in France, Greece, Lithuania, Norway, Spain, and the United Kingdom). We measured concentrations of perfluorooctane sulfonate, perfluorooctanoate, perfluorononanoate, perfluorohexane sulfonate, and perfluoroundecanoate in maternal blood. We assessed concentrations of alanine aminotransferase, aspartate aminotransferase, and gamma‐glutamyltransferase in child serum. Using Bayesian kernel machine regression, we found that higher exposure to PFAS during pregnancy was associated with higher liver enzyme levels in children. We also measured child serum metabolomics through a targeted assay and found significant perturbations in amino acid and glycerophospholipid metabolism associated with prenatal PFAS. A latent variable analysis identified a profile of children at high risk of liver injury (odds ratio, 1.56; 95% confidence interval, 1.21‐1.92) that was characterized by high prenatal exposure to PFAS and increased serum levels of branched‐chain amino acids (valine, leucine, and isoleucine), aromatic amino acids (tryptophan and phenylalanine), and glycerophospholipids (phosphatidylcholine PC aa C36:1 and Lyso‐PC a C18:1).
Conclusions
Developmental exposure to PFAS can contribute to pediatric liver injury.
Summary
Many chronic pain patients are refractory to treatment, which leads to the suspicion that somehow they are not fully effective and probably some mechanism of pain generation and/or ...maintenance is still unknown. The aim of this cross‐sectional study was to provide evidence‐based data on pain mechanisms in different types of chronic pain conditions. Eighty women, with 18–65 years old, were included, divided into four groups: myofascial pain of the masticatory muscles (n = 20), fibromyalgia (n = 20), chronic daily headache and healthy volunteers (n = 20). All patients were submitted to quantitative sensory tests: pressure pain threshold, mechanical detection threshold, mechanical pain threshold, ischaemic pain tolerance, cold pain sensitivity, aftersensation, wind‐up ratio and conditioned pain modulation. Current perception threshold was also determined (Neurometer CPT/C – Neurotron®). Three different zones were evaluated: trigeminal (masseter muscle), cervical and extratrigeminal (thenar eminence). Data were recorded and subjected to statistical analysis (anova, Tukey and Student's t‐tests). Masticatory myofascial pain, fibromyalgia and chronic daily headache individuals presented lower pressure pain thresholds than healthy volunteers (P = 0·00). Chronic daily headache individuals had a significantly higher mechanical detection threshold than healthy volunteers (P = 0·01). Individuals of the symptomatic groups showed lower values for mechanical pain threshold and for ischaemic pain tolerance (P = 0·00) than healthy volunteers. The ability to activate the mechanism of endogenous modulation is impaired in women with fibromyalgia and myofascial pain (P = 0·00). These results reinforce evidence of central sensitisation and impaired endogenous modulation system in individuals with myofascial pain, fibromyalgia and chronic daily headache.
Summary The aim of this study was to determine the prevalence of signs and symptoms of temporomandibular disorders (TMD) and otologic symptoms in patients with and without tinnitus. The influence of ...the level of depression was also addressed. The tinnitus group was comprised of 100 patients with tinnitus, and control group was comprised of 100 individuals without tinnitus. All subjects were evaluated using the research diagnostic criteria for temporomandibular disorders (RDC/TMD) to determine the presence of TMD and depression level. Chi‐square, Spearman Correlation and Mann‐Whitney tests were used in statistical analysis, with a 5% significance level. TMD signs and symptoms were detected in 85% of patients with tinnitus and in 55% of controls (P ≤ 0·001). The severity of pain and higher depression levels were positively associated with tinnitus (P ≤ 0·001). It was concluded that tinnitus is associated with TMD and with otalgia, dizziness/vertigo, stuffy sensations, hypoacusis sensation and hyperacusis, as well as with higher depression levels.
Summary
There is no clear evidence on how a headache attributed to temporomandibular disorder (TMD) can hinder the improvement of facial pain and masticatory muscle pain. The aim of this study was to ...measure the impact of a TMD‐attributed headache on masticatory myofascial (MMF) pain management. The sample was comprised of adults with MMF pain measured according to the revised research diagnostic criteria for temporomandibular disorders (RDC/TMD) and additionally diagnosed with (Group 1, n = 17) or without (Group 2, n = 20) a TMD‐attributed headache. Both groups received instructions on how to implement behavioural changes and use a stabilisation appliance for 5 months. The reported facial pain intensity (visual analogue scale – VAS) and pressure pain threshold (PPT – kgf cm−2) of the anterior temporalis, masseter and right forearm were measured at three assessment time points. Two‐way anova was applied to the data, considering a 5% significance level. All groups had a reduction in their reported facial pain intensity (P < 0·001). Mean and standard deviation (SD) PPT values, from 1·33 (0·54) to 1·96 (1·06) kgf cm−2 for the anterior temporalis in Group 1 (P = 0·016), and from 1·27 (0·35) to 1·72 (0·60) kgf cm−2 for the masseter in Group 2 (P = 0·013), had significant improvement considering baseline versus the 5th‐month assessment. However, no differences between the groups were found (P > 0·100). A TMD‐attributed headache in patients with MMF pain does not negatively impact pain management, but does change the pattern for muscle pain improvement.
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