Perspectives on next steps in classification of oro‐facial pain – Part 3: biomarkers of chronic oro‐facial pain – from research to clinic

The purpose of this study was to review the current status of biomarkers used in oro‐facial pain conditions. Specifically, we critically appraise their relative strengths and weaknesses for assessing mechanisms associated with the oro‐facial pain conditions and interpret that information in the light of their current value for use in diagnosis. In the third section, we explore biomarkers through the perspective of ontological realism. We discuss ontological problems of biomarkers as currently widely conceptualised and implemented. This leads to recommendations for research practice aimed to a better understanding of the potential contribution that biomarkers might make to oro‐facial pain diagnosis and thereby fulfil our goal for an expanded multidimensional framework for oro‐facial pain conditions that would include a third axis.     

Tactile sensory and pain thresholds in the face and tongue of subjects asymptomatic for oro‐facial pain and headache

The aim of this study was to examine the tactile sensory and pain thresholds in the face, tongue, hand and finger of subjects asymptomatic for pain. Sixteen healthy volunteers (eight men and eight women, mean age 35·7 years, range 27–41) participated. Using Semmes–Weinstein monofilaments, the tactile detection threshold (TDT) and the filament‐prick pain detection threshold (FPT) were measured at five sites: on the cheek skin (CS), tongue tip (TT), palm side of the thenar skin (TS), dorsum of the hand (DH) and the finger tip (FT). The difference between the tactile sensory and pain threshold (FPT–TDT) was also calculated. Both for the TDT and FPT, TT and DH had the lowest and highest values, respectively. As for the FPT–TDT, there were no significant differences among the measurement sites. As the difference between FPT and TDT (FPT–TDT) is known to be an important consideration in interpreting QST (quantitative sensory testing) data and can be altered by neuropathology, taking the FPT–TDT as a new parameter in addition to the TDT and FPT separately would be useful for case–control studies on oro‐facial pain patients with trigeminal neuralgia, atypical facial pain/atypical odontalgia and burning mouth syndrome/glossodynia.     

Pharmacological treatment of oro‐facial pain – health technology assessment including a systematic review with network meta‐analysis

This health technology assessment evaluated the efficacy of pharmacological treatment in patients with oro‐facial pain. Randomised controlled trials were included if they reported pharmacological treatment in patients ≥18 years with chronic (≥3 months) oro‐facial pain. Patients were divided into subgroups: TMD‐muscle [temporomandibular disorders (TMD) mainly associated with myalgia]; TMD‐joint (TMD mainly associated with temporomandibular joint pain); and burning mouth syndrome (BMS). The primary outcome was pain intensity reduction after pharmacological treatment. The scientific quality of the evidence was rated according to GRADE. An electronic search in PubMed, Cochrane Library, and EMBASE from database inception to 1 March 2017 combined with a handsearch identified 1552 articles. After screening of abstracts, 178 articles were reviewed in full text and 57 studies met the inclusion criteria. After risk of bias assessment, 41 articles remained: 15 studies on 790 patients classified as TMD‐joint, nine on 375 patients classified as TMD‐muscle and 17 on 868 patients with BMS. Of these, eight studies on TMD‐muscle, and five on BMS were included in separate network meta‐analysis. The narrative synthesis suggests that NSAIDs as well as corticosteroid and hyaluronate injections are effective treatments for TMD‐joint pain. The network meta‐analysis showed that clonazepam and capsaicin reduced pain intensity in BMS, and the muscle relaxant cyclobenzaprine, for the TMD‐muscle group. In conclusion, based on a limited number of studies, evidence provided with network meta‐analysis showed that clonazepam and capsaicin are effective in treatment of BMS and that the muscle relaxant cyclobenzaprine has a positive treatment effect for TMD‐muscle pain.     

Normative values for the oro‐facial Esthetic Scale in Sweden

This study reports the findings and challenges of the assessment of oro‐facial aesthetics in the Swedish general population and the development of normative values for the self‐reporting Orofacial Esthetic Scale (OES). In a Swedish national sample of 1406 adult subjects (response rate: 47%), OES decile norms were established. The influence of sociodemographics (gender, age, and education), oral health status and general health status on OES scores was analysed. Mean ± standard deviation of OES scores was 50·3 ± 15·6 units (0, worst score; 70, best score); <1% of the subjects had the minimum score of 0, and 11% had the maximum score of 70 OES units. Orofacial Esthetic Scale score differences were (i) substantial (>5 OES units) for subjects with excellent/very good versus good to poor oral or general health status; ii) small (2 units), but statistically significant for gender (P = 0·01) and two age groups (P = 0·02), and (iii) absent for subjects with college versus no college education (P = 0·31) or with and without dentures (P = 0·90). To estimate normative values for a self‐reporting health status, instrument is considered an important step in standardisation, and the developed norms provide a frame of reference in the general population to interpret the Orofacial Esthetic Scale scores.     

Assessment of risk factors for oro‐facial pain and recent developments in classification: implications for management

Oro‐facial pain research has during the last decades provided important novel insights into the basic underlying mechanisms, the need for standardised diagnostic procedures and classification systems, and multiple treatment options for successful rehabilitation of the patient in pain. Notwithstanding the significant progress in our knowledge spanning from molecules to chair, there may also be limitations in our ability to integrate and interpret the tremendous amount of new data and information, in particular in terms of the clinical implications and overriding conceptual models for oro‐facial pain. The aim of the present narrative review is to briefly summarise some of the current thoughts on oro‐facial pain mechanisms and recent attempts to identify biomarkers and risk factors leading to the proposal of a new risk assessment diagram for oro‐facial pain (RADOP) and a provocative new concept based on stochastic variation between multiple risk factors. Finally, the implications for novel management strategies will briefly be discussed.     

Perspectives on next steps in classification of oro‐facial pain – part 2: role of psychosocial factors

This study was initiated by a symposium, in which the present authors contributed, organised by the International RDC/TMD Consortium Network in March 2013. The purpose of the study was to review the status of biobehavioural research – both quantitative and qualitative – related to oro‐facial pain (OFP) with respect to the aetiology, pathophysiology, diagnosis and management of OFP conditions, and how this information can optimally be used for developing a structured OFP classification system for research. In particular, we address representation of psychosocial entities in classification systems, use of qualitative research to identify and understand the full scope of psychosocial entities and their interaction, and the usage of classification system for guiding treatment. We then provide recommendations for addressing these problems, including how ontological principles can inform this process.     

Development of the Chinese version of the Oro‐facial Esthetic Scale

The aim of this study was to investigate the psychometric properties of the Oro‐facial Esthetic Scale among Chinese‐speaking patients. The original Oro‐facial Esthetic Scale was cross‐culturally adapted in accordance with the international standards to develop a Chinese version (OES‐C). Unlike the original Oro‐facial Esthetic Scale, the version employed in this study used a 5‐point Likert scale with items rated from unsatisfactory to most satisfactory. Psychometric evaluation included the reliability and validity of the OES‐C. The reliability of the OES‐C was determined through internal consistency and test–retest methods. The validity of OES‐C was analysed by content validity, discriminative validity, construct validity and convergent validity. The corrected item‐total correlation coefficients of the OES‐C ranged from 0·859 to 0·910. The inter‐item correlation coefficients between each two of the eight items of the OES‐C ranged from 0·766 to 0·922. The values of ICC ranged from 0·79 (95% CI = 0·54–0·98) to 0·93 (95% CI = 0·87–0·99), indicating an excellent agreement. Construct validity was proved by the presence of one‐factor structure that accounted for 83·507% of the variance and fitted well into the model. Convergent validity was confirmed by the association between OES‐C scores and self‐reported oral aesthetics and three questions from the Oral Health Impact Profile related to aesthetics (correlation coefficients ranged from ?0·830 to ?0·702, P < 0·001). OES‐C scores discriminated aesthetically impaired patients from healthy controls. This study provides preliminary evidence concerning the reliability and validity of the OES‐C. The results show that the OES‐C may be a useful tool for assessment of oro‐facial esthetics in China.     

Salivary cortisol and psychological factors in women with chronic and acute oro‐facial pain

The aim of this study was to compare the salivary cortisol level, pain intensity and psychological factors between patients with chronic and acute oro‐facial pain (OP) and pain‐free subjects. Twenty‐seven females with chronic OP (a diagnosis of myofascial pain according to the Research Diagnostic Criteria for Temporomandibular Disorders with at least 6 months duration), 24 females with acute OP (<10 days duration) and 27 pain‐free females participated. Morning saliva was collected from all participants for analyses of the cortisol level. The pain intensity was assessed on a 0–10 numeric rating scale. The participants were evaluated by the Symptom Checklist 90‐revised for levels of depression and somatisation, and the Perceived Stress Scale. The cortisol levels among the three patient groups were similar with no significant group differences. The median (interquartile range) current pain level did not differ between chronic and acute OP and was, respectively, 5 (4) and 5 (3). Patients with chronic OP showed significantly higher scores for depression, somatisation and perceived stress compared with patients with acute OP (Ps < 0·001), but there were no significant differences between acute OP and controls. To conclude, there were no differences in cortisol level between groups, despite significant higher levels of depression, somatisation and perceived stress in patients with chronic OP. This shows that psychological distress has a more important role in chronic than in acute OP. However, the relation between pain, adreno‐cortical activity and psychological distress is complex and warrants further investigation.     

Quantitative examination of isometric tongue protrusion forces in children with oro‐facial dysfunctions or myofunctional disorders

Oro‐facial dysfunctions (OFD) or oro‐facial myofunctional disorders in children lead to severe problems in teeth and jaw position, articulation, chewing and swallowing. The forces of the tongue, the central muscle for articulation, chewing and swallowing are focused on in several studies. In this examination, isometric tongue protrusion forces (TPF) of children with OFD and controls were compared. Thirty participants with OFD and 30 controls were presented a target force level as a straight line on a monitor that they were supposed to match by generating an isometric tongue force for different target levels (0.25 N and 0.5 N). Correlations of the severity of OFD (symptom score) with the capacities of the TPF 0.25 N and 0.5 N were calculated. Statistical differences were obvious in TPF variability and the accuracy, depending on the weight. Tongue contact time, expressed as per cent (TCT, total contact: 100%), was significantly lower in children with OFD (P = .005). Mean and median TPF was not different between groups. The predictive value of TPF for OFD revealed a level of 58.6% for TPF 0.25 N and 74.5% for TPF 0.5 N. Correlations of the severity of OFD were seen for some parameters. Subjects with OFD show significantly lower competencies in accuracy and endurance of tongue protrusion forces. This may have a high impact on phenotyping children with OFD and influence therapeutical approaches.     

Transcranial direct current stimulation and exercises for treatment of chronic temporomandibular disorders: a blind randomised‐controlled trial

To evaluate the effect of adding transcranial direct current stimulation (tDCS) to exercises for chronic pain, dysfunction and quality of life in subjects with temporomandibular disorders (TMD). Participants were selected based on the RDC/TMD criteria and assessed for pain intensity, pressure pain threshold over temporomandibular joint and cervical muscles and quality of life. After initial assessment, all individuals underwent a 4‐week protocol of exercises and manual therapy, together with active or sham primary motor cortex tDCS. Stimulation was delivered through sponge electrodes, with 2 mA amplitude, for 20 min daily, over the first 5 days of the trial. A total of 32 subjects (mean age 24·7 ± 6·8 years) participated in the evaluations and treatment protocol. Mean pain intensity pre‐treatment was 5·5 ± 1·4 for active tDCS group, and 6·3 ± 1·2 for sham tDCS. Both groups showed a decrease in pain intensity scores during the trial period (time factor – F_4·5,137·5 = 28·7, P < 0·001; group factor – F_1·0,30·0 = 7·7, P < 0·05). However, there were no differences between the groups regarding change in pain intensity (time*group interaction – F_4·5,137·5 = 1·5, P = 0·137). This result remained the same after 5 months (t‐test t = 0·29, P > 0·05). Pressure pain thresholds decrease and improvement in quality of life were also noticeable in both groups, but again without significant differences between them. Absolute benefit increase was 37·5% (CI 95%: ?15·9% to 90·9%), and number needed to treat was 2·66. This study suggests that there is no additional benefit in adding tDCS to exercises for the treatment of chronic TMD in young adults.     

Reliability of intra‐oral quantitative sensory testing (QST) in patients with atypical odontalgia and healthy controls – a multicentre study

The reliability of comprehensive intra‐oral quantitative sensory testing (QST) protocol has not been examined systematically in patients with chronic oro‐facial pain. The aim of the present multicentre study was to examine test–retest and interexaminer reliability of intra‐oral QST measures in terms of absolute values and z‐scores as well as within‐session coefficients of variation (CV) values in patients with atypical odontalgia (AO) and healthy pain‐free controls. Forty‐five patients with AO and 68 healthy controls were subjected to bilateral intra‐oral gingival QST and unilateral extratrigeminal QST (thenar) on three occasions (twice on 1 day by two different examiners and once approximately 1 week later by one of the examiners). Intra‐class correlation coefficients and kappa values for interexaminer and test–retest reliability were computed. Most of the standardised intra‐oral QST measures showed fair to excellent interexaminer (9–12 of 13 measures) and test–retest (7–11 of 13 measures) reliability. Furthermore, no robust differences in reliability measures or within‐session variability (CV) were detected between patients with AO and the healthy reference group. These reliability results in chronic orofacial pain patients support earlier suggestions based on data from healthy subjects that intra‐oral QST is sufficiently reliable for use as a part of a comprehensive evaluation of patients with somatosensory disturbances or neuropathic pain in the trigeminal region.     

Long‐term side effects on the temporomandibular joints and oro‐facial function in patients with obstructive sleep apnoea treated with a mandibular advancement device

Patients with obstructive sleep apnoea (OSA) in long‐term treatment with a mandibular advancement device (MAD) to increase the upper airway space may develop changes in the temporomandibular joint (TMJ) and the oro‐facial function due to the protruded jaw position during sleep. The aim was to investigate the influence of long‐term MAD treatment on the TMJs, oro‐facial function and occlusion. This prospective study included 30 men and 13 women (median age 54) with OSA [Apnoea–Hypopnoea Index (AHI): 7–57]. They were examined with the Nordic Orofacial Test Screening (NOT‐S), the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and cone beam computed tomography (CBCT) of the TMJs. The examination was performed before MAD treatment (T0), and 3–6 months (T1, no CBCT), 1 year (T2) and 3 years (T3) after treatment start. The results were analysed as long term (T0–T3, n = 14) and short term (T0–T2, n = 24) by t‐test, Fisher's exact test and anova . Both long‐ and short‐term analyses revealed a reduction in AHI (P < 0·002). Significant long term were increased scores in the NOT‐S Interview (P < 0·045), reduced vertical overbite (P < 0·031) and increased jaw protrusive movement (P < 0·027). TMJ changes were found as joint sounds in terms of reciprocal clicking and crepitus, short term as a decrease and subsequent recurrence (P < 0·053; P < 0·037). No significant radiological changes were found. In conclusion, MAD treatment is beneficial to some OSA patients, but might induce changes in the TMJs, the oro‐facial function and the occlusion. However, these changes seemed to be less harmful than previously reported with careful adaptation, control and follow‐ups.     

Social support in chronic pain: development and preliminary psychometric assessment of a new instrument

Satisfaction with social support (pain-relevant social support) may influence pain experience and behaviour in patients with chronic pain. Prior studies on measurement of social support, however, have been limited by the use of general, rather than of pain-specific assessment instruments. In this study, a new pain-relevant social support instrument, the Social support and Pain Questionnaire (SPQ), is presented together with an evaluation of its psychometric properties. A literature search was performed to establish different aspects of social support. For each of the six aspects found, one item was selected for inclusion in the new questionnaire. The draft version of the questionnaire was field tested. Thereafter, the psychometric properties of the SPQ were assessed in 250 patients with oro-facial pain. Principal component analysis (n=250) showed that the SPQ had a one-factor structure. The test-retest reliability of the SPQ (in a subsample of 54 patients) was fair-to-good (R=0·70; P<0·000). Convergent validity, as compared with a non-specific social support instrument, was good (n=140; R=0·54; P<0·000). The SPQ is a valid and reliable instrument, which offers the possibility to explore the patient's satisfaction with pain-related social support. With the SPQ, a useful tool to assess the influence of social support in patients with various types of pain is provided.