2020: Renewing the paradigms for orofacial pain / 2020: renovando los paradigmas para el dolor orofacial

Abstract In 2020, two important changes were adapted by the international health community: a new definition of pain and a new classification for orofacial pain conditions. With these changes new tasks and challenges also emerged, and clinicians from several disciplines begun to adopt and reconsidered classic paradigms, and the policies derived from them. This new perspective article, examine the new definition of pain proposed by the International Association for the Study of Pain, and the new International Classification of Orofacial Pain; analyzing the positive impact and further perspectives of these.

Resumen En 2020, dos importantes cambios fueron adaptados por la comunidad internacional en salud: una nueva definición de dolor y una nueva clasificación para las condiciones de dolor orofacial. Con estos cambios, también emergieron nuevos retos y tareas, y los clínicos de diversas disciplinas empezaron adaptar y reconsiderar los paradigmas clásicos; y las políticas derivadas de estos. En este artículo de nueva perspectiva, examinaremos nueva definición de dolor propuesta por la Asociación Internacional para el Estudio del Dolor, y la nueva Clasificación Internacional de Dolor Orofacial; analizando el impacto positivo y las próximas perspectivas de estos cambios.

The role of spatial frequencies for facial pain categorization.

Studies on low-level visual information underlying pain categorization have led to inconsistent findings. Some show an advantage for low spatial frequency information (SFs) and others a preponderance of mid SFs. This study aims to clarify this gap in knowledge since these results have different theoretical and practical implications, such as how far away an observer can be in order to categorize pain. This study addresses this question by using two complementary methods: a data-driven method without a priori expectations about the most useful SFs for pain recognition and a more ecological method that simulates the distance of stimuli presentation. We reveal a broad range of important SFs for pain recognition starting from low to relatively high SFs and showed that performance is optimal in a short to medium distance (1.2-4.8 m) but declines significantly when mid SFs are no longer available. This study reconciles previous results that show an advantage of LSFs over HSFs when using arbitrary cutoffs, but above all reveal the prominent role of mid-SFs for pain recognition across two complementary experimental tasks.

Chronic orofacial pain.

While pain chronicity in general has been defined as pain lasting for more than 3 months, this definition is not useful in orofacial pain (OFP) and headache (HA). Instead, chronicity in OFP and HA is defined as pain occurring on more than 15 days per month and lasting for more than 4 h daily for at least the last 3 months. This definition excludes the periodic shortlasting pains that often recur in the face and head, but are not essentially chronic. Although the headache field has adopted this definition, chronic orofacial pain is still poorly defined. In this article, we discuss current thinking of chronicity in pain and examine the term 'chronic orofacial pain' (COFP). We discuss the entities that make up COFP and analyze the term's usefulness in clinical practice and epidemiology.

Oro-facial pain and temporomandibular disorders classification systems: A critical appraisal and future directions.

It is a difficult undertaking to design a classification system for any disease entity, let alone for oro-facial pain (OFP) and more specifically for temporomandibular disorders (TMD). A further complication of this task is that both physical and psychosocial variables must be included. To augment this process, a two-step systematic review, adhering to PRISMA guidelines, of the classification systems published during the last 20 years for OFP and TMD was performed. The first search step identified 190 potential citations which ultimately resulted in only 17 articles being included for in-depth analysis and review. The second step resulted in only 5 articles being selected for inclusion in this review. Five additional articles and four classification guidelines/criteria were also included due to expansion of the search criteria. Thus, in total, 14 documents comprising articles and guidelines/criteria (8 proposals of classification systems for OFP; 6 for TMD) were selected for inclusion in the systematic review. For each, a discussion as to their advantages, strengths and limitations was provided. Suggestions regarding the future direction for improving the classification process with the use of ontological principles rather than taxonomy are discussed. Furthermore, the potential for expanding the scope of axes included in existing classification systems, to include genetic, epigenetic and neurobiological variables, is explored. It is therefore recommended that future classification system proposals be based on combined approaches aiming to provide archetypal treatment-oriented classifications.

Evaluation of Pain Syndromes, Headache, and Temporomandibular Joint Disorders in Children.

After a thorough review of the history and presentation of a child's facial pain, a targeted head and neck examination is critical to the appropriate diagnosis of facial pain and temporomandibular joint disorders. It is critical to distinguish between the structural (trauma, degenerative disease, and tumor) and nonstructural (neurogenic, myogenic, and psychological) causes of pain, which will allow for incorporation of appropriate strategies of medical, psychological, dental, and surgical therapies.

Classification: The key to understanding facial pain.

It is indisputable that the global scientific advances in headache research, be it bench or bedside, have benefited enormously from the operational diagnostic criteria published in 1988. Today, this classification system is indispensable. The reason for this success is a low inter-rater variability. In general, orofacial pain conditions are less well characterised - with the noticeable exemption of temporomandibular disorder pain. Tremendous work has been put into changing this, and significant progress has been achieved - in particular, in terms of the clinical implications and overriding conceptual models for oro-facial pain. Scientific classifications have only one goal: To provide a scientific agreement about the main features of an object of research and a scientific consensus regarding the name. The main significance is not the fact that a good classification offers a detailed and accurate image of the reality. If we want to overcome the obstacles of different competing classification systems, we need to overcome specialisation borders. The key to success is to understand that such a definition does not mirror all possible clinical facets of a given pain condition but is simply a convention - that is, a consensus on a word used for a pain condition. Simply speaking, a classification creates a common language to be used by more than one profession. It will be crucial to define any given pain condition as precisely and rigid as possible, in order to ensure a homogenous population. Only this ensures a low inter-rater variability, which consequently allows combining and comparing research on a population across different professional settings. This is not easy for chronic facial pain without verifiable morphological cause or structural lesions, as these syndromes are often rather featureless. The new IASP classification of chronic pain is a big step forward to a better characterisation of such conditions, and will trigger future work on a new and operationalised classification of oro-facial pain.

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.

[Classification of pain in the orofacial and craniofacial regions]. / Classificatie van pijn in het orofaciale en craniofaciale gebied.

Pain is a multidimensional, subjective phenomenon that can only be understood within the context of an individual operating in a specific environment. As a consequence, it is difficult from an objective standpoint to satisfy the established criteria for classification. In general, it is the case that available classification systems can only partially capture pain in all of its complexity. There are various general and specific classification systems. In 2017, the International Classification of Diseases will be complemented with classification possibilities related to chronic pain. Recently, a committee established by the Dutch Pain Society has formulated a proposal for the development of a definition and classification system for chronic pain to be applied in the Netherlands.

[Measuring orofacial pain]. / Pijnmeting bij orofaciale pijn.

Pain is a complex neuro-physiological phenomenon affecting mind and behaviour, and is in turn also affected by psyche and behaviour. Differences among individuals in modulation, interpretation and expression complicate the comparison of pain between patients. Pain is a subjective experience and can be expressed by the patient in many different ways. In addition, influential factors from a bio-psycho-social perspective have to be taken into consideration: the interaction among somatic, psychological and social factors determines the ultimate pain experience and pain behaviour. Measuring pain therefor requires a multi-dimensional approach in which the pain, observed from various levels, and the associated problems can be determined.

Classification and Differential Diagnosis of Oral and Maxillofacial Pain.

Pain in the orofacial region is a common presenting symptom. The majority of symptoms are related to dental disease and the cause can readily be established, the problem dealt with, and the pain eliminated. However, pain may persist and defy attempts at treatment. Intractable oral or facial pain can be diagnostically challenging. To make a definitive diagnosis and initiate proper treatment, a rigorous protocol for evaluation includes a thorough history and an appropriate comprehensive clinical examination and diagnostic testing, including chief complaint, history of present illness, medical history, physical examination, diagnostic studies, including imaging, and psychosocial evaluation.

Cranial Neuralgias.

Advances in diagnostic modalities have improved the understanding of the pathophysiology of neuropathic pain involving head and face. Recent updates in nomenclature of cranial neuralgias and facial pain have rationalized accurate diagnosis. Clear diagnosis and localization of pain generators are paramount, leading to better use of medical and targeted surgical treatments.

Orofacial Pain during Mastication in People with Dementia: Reliability Testing of the Orofacial Pain Scale for Non-Verbal Individuals.

Objectives. The aim of this study was to establish the reliability of the "chewing" subscale of the OPS-NVI, a novel tool designed to estimate presence and severity of orofacial pain in nonverbal patients. Methods. The OPS-NVI consists of 16 items for observed behavior, classified into four categories and a subjective estimate of pain. Two observers used the OPS-NVI for 237 video clips of people with dementia in Dutch nursing homes during their meal to observe their behavior and to estimate the intensity of orofacial pain. Six weeks later, the same observers rated the video clips a second time. Results. Bottom and ceiling effects for some items were found. This resulted in exclusion of these items from the statistical analyses. The categories which included the remaining items (n = 6) showed reliability varying between fair-to-good and excellent (interobserver reliability, ICC: 0.40-0.47; intraobserver reliability, ICC: 0.40-0.92). Conclusions. The "chewing" subscale of the OPS-NVI showed a fair-to-good to excellent interobserver and intraobserver reliability in this dementia population. This study contributes to the validation process of the OPS-NVI as a whole and stresses the need for further assessment of the reliability of the OPS-NVI with subjects that might already show signs of orofacial pain.

[Orofacial pain - Trigeminal neuralgia and posttraumatic trigeminal neuropathy: Common features and differences]. / Orofazialer Schmerz - Trigeminusneuralgie und posttraumatische Trigeminusneuropathie : Gemeinsamkeiten und Unterschiede.

Neuropathic pain is the result of a lesion or disease of the somatosensory system in the peripheral or central nervous system. Classical trigeminal neuralgia and posttraumatic trigeminal neuropathy are pain disorders which oral and maxillofacial surgeons and dentists are confronted with in the differential diagnostics in routine daily practice. The etiopathogenesis of classical trigeminal neuralgia is attributable to pathological blood vessel-nerve contact in the trigeminal nerve root entry zone to the brain stem. The typical pain symptoms are characterized by sudden stabbing pain attacks. The pharmaceutical prophylaxis is based on the individually titrated administration of anticonvulsant drugs. The indications for interventional treatment are dependent on the course, response to drug treatment, resilience and wishes of the patient. The neuropathic mechanism of posttraumatic trigeminal neuropathy originates from nerve damage, which leads to peripheral and central sensitization with lowering of the pain threshold and multiple somatosensory disorders. The prophylaxis consists of avoidance of excessive acute and long-lasting pain stimuli. Against the background of the biopsychosocial pain model, the treatment of posttraumatic trigeminal neuropathy necessitates a multimodal, interdisciplinary concept.

Prevalence of the different Axis I clinical subtypes in a sample of patients with orofacial pain and temporomandibular disorders in the Andalusian Healthcare Service.

BACKGROUND: The main objective of this paper is to analyze the prevalence of each of the different clinical subtypes of temporomandibular disorders (TMD) in a sample of patients with this pathology. In addition, a second objective was to analyze their distribution according to gender. MATERIAL AND METHODS: To this end, the results of 1603 patients who went to the Unit of Temporomandibular Disorders in the Córdoba Healthcare District because they suffered from this pathology were analyzed. In order to diagnose them, the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were applied, analyzing the different Axis I subtypes (myopathy, discopathy and arthropathy) and obtaining the combined Axis I for each patient and the relation of all these variables according to gender. The null-hypothesis test confirmed the lack of connection between the gender variable and the different subtypes in the clinical analysis, and between the former and the combined Axis I of the RDC/TMD. RESULTS: The prevalence was high for the muscle disorders subtype in general, showing an 88.7% prevalence, while the presence of discopathies or arthropathies was much lower. Among discopathies, the most frequent ones were disc displacements with reduction, with 39.7% and 42.8% for the left and right temporomandibular joints (TMJ), respectively, while the prevalence of arthropathies was 26.3% for the right TMJ and 32.9% for the left TMJ. The bivariate analysis on the connection with gender reveals a p≥ 0.05 value for the muscle and arthralgia subtypes. CONCLUSIONS: The patients seen at the TMD Unit where mostly middle-aged women whose main clinical axis subtype was the muscle disorder subtype. For their part, both discopathies and arthropathies, although present, are much less prevalent.

Pain Part 5a: Chronic (Neuropathic) Orofacial Pain.

Neuropathic pain is a significant social and economic burden. Back pain, joint pain and headaches affect over 30% of the population. Chronic orofacial pain is a common condition and is difficult to diagnose and manage. This two-part paper aims to provide an overview of novel understanding of neuropathic pain, and furnish clinical teams with an update on the less common and less well-recognized chronic orofacial conditions. Headaches and temporomandibular disorders are the most common conditions and are covered in separate papers (6 and 10). Trigeminal neuralgia, burning mouth, and trigeminal autonomic cephalgias are also covered in separate papers (7, 8 and 9). The remaining conditions: post-traumatic neuropathy (nerve injury); and persistent idiopathic facial pain and atypical odontalgia are discussed in this and the following paper. Clinical Relevance: Neuropathic pain, though rare, is a consequence of dental treatment. Nerve injury in relation to M3M surgery, dental implants, endodontics and local anaesthesia result in 70% of affected patients experiencing chronic neuropathic pain.

Psychometric Properties of the Multidimensional Pain Inventory Applied to Brazilian Patients with Orofacial Pain.

AIMS: To evaluate the psychometric properties of the Multidimensional Pain Inventory (MPI) in a Brazilian sample of patients with orofacial pain. METHODS: A total of 1,925 adult patients, who sought dental care in the School of Dentistry of São Paulo State University's Araraquara campus, were invited to participate; 62.5% (n=1,203) agreed to participate. Of these, 436 presented with orofacial pain and were included. The mean age was 39.9 (SD=13.6) years and 74.5% were female. Confirmatory factor analysis was conducted using χ²/df, comparative fit index, goodness of fit index, and root mean square error of approximation as indices of goodness of fit. Convergent validity was estimated by the average variance extracted and composite reliability, and internal consistency by Cronbach's alpha standardized coefficient (α). The stability of the models was tested in independent samples (test and validation; dental pain and orofacial pain). The factorial invariance was estimated by multigroup analysis (Δχ²). RESULTS: Factorial, convergent validity, and internal consistency were adequate in all three parts of the MPI. To achieve this adequate fit for Part 1, item 15 needed to be deleted (λ=0.13). Discriminant validity was compromised between the factors "activities outside the home" and "social activities" of Part 3 of the MPI in the total sample, validation sample, and in patients with dental pain and with orofacial pain. A strong invariance between different subsamples from the three parts of the MPI was detected. CONCLUSION: The MPI produced valid, reliable, and stable data for pain assessment among Brazilian patients with orofacial pain.

[Facial pain].

Diagnosis and treatment of facial pain is a problem for physicians of different specialties (neurologists, dentists, surgeons, oculists, otolaryngologists and psychiatrists). A classification of this pathology is far from ideal and an interdisciplinary comprehensive approach is needed. Current approaches to etiotropic, symptomatic and pathogenetic treatment of patients with most frequent variants of orofacial pain are presented.