Sleep disorders and orofacial pain: insights for dental practice

In dental sleep medicine several sleep disorders commonly coexist with pain, contributing to complex clinical presentations which might affect the provision of appropriate and timely treatment. There are associations between sleep disorders and pain in general, as well as with specific orofacial pain conditions. As many as five of six patients with orofacial pain can present with sleep problems. The comorbidity of orofacial pain and sleep disorders overlays a complex web of altered neurobiological mechanisms that predispose to the chronification of orofacial pain. This review discusses the relationship between orofacial pain and sleep disorders and highlights their interactions and the neurobiological mechanisms underlying those relationships.

The enigma of sleep: Implications of sleep neuroscience for the dental clinician and patient

BACKGROUND

Sleep disturbances have been shown to result in considerable morbidity and mortality. It is important for dental clinicians to understand the neuroscience behind sleep disorders.

TYPES OF STUDIES REVIEWED

The authors conducted a search of the literature published from January 1990 through March 2024 of sleep medicine-related articles, with a focus on neuroscience. The authors prioritized articles about the science of sleep as related to dental medicine.

RESULTS

The authors found a proliferation of articles related to sleep neuroscience along with its implications in dental medicine. The authors also found that the intricate neuroscientific principles of sleep medicine are being investigated robustly. The salient features of, and the differences between, central and obstructive sleep apneas have been elucidated. Sleep genes, such as CRY, PER1, PER2, and CLOCK, and their relationship to cancer and neurodegeneration are also additions to this rapidly developing science.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental clinician has the potential to be the first to screen patients for possible sleep disorders and make prompt referrals to the appropriate medical professionals. This can be lifesaving as well as minimize potential future morbidity for the patient.

Association between obstructive sleep apnea and temporomandibular disorders: A meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a very common condition in patients with temporomandibular disorders (TMD). However, there is little evidence of a connection between them.

OBJECTIVE

The aim of this systematic review and meta-analysis is to assess the association between OSA and TMD in adult population.

METHODS

Case-control, cross-sectional and cohort studies on the association between TMD and OSA were searched in the EMBASE, LILACS, LIVIVO, PubMed/MEDLINE, Scopus, Web of Science, Google Scholar, Open Grey and Pro Quest databases. TMD should be assessed using Research Diagnostic Criteria (RDC/TMD) or Diagnostic Criteria (DC/TMD) and OSA using polysomnography (PSG) and/or a validated questionnaire. The risk of bias was evaluated using the Joanna Briggs Institute Critical Assessment Checklists; and an association meta-analysis was performed. The effect measure included the odds ratio (OR) in dichotomous variables and a 95% confidence interval (CI). Certainty of evidence was determined by analysing groups using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Out of the 1024 articles screened, 7 met the inclusion criteria for the qualitative synthesis, and 6 for quantitative analysis. All articles were classified at low risk of bias. A positive association with OSA was found in patients with TMD (OR = 2.61; 95% CI = 2.31, 2.95). A significant association was also found irrespective to the OSA diagnostic methods applied (for studies using PSG + validated questionnaires: OR = 2.74; 95% CI = 2.11, 3.57; for studies using validated questionnaires only: OR = 2.55; 95% CI = 2.22, 2.92). GRADE was moderate.

CONCLUSION

Patients with TMD presented a significant association with OSA regardless of the OSA diagnostic method (PSG and/or validated questionnaires). OSA screening should be part of the TMD examination routine. Furthermore, due to the different OSA assessment methods used and the small number of studies included, there is a need to include a larger number of studies using PSG to better elucidate this association.

Association of night-time sleep and daytime napping with painful temporomandibular disorder

BACKGROUND

Painful temporomandibular disorder (TMD) is the common cause of chronic oro-facial pain, which may interfere with sleep. Previous studies have documented an association between sleep and TMD.

OBJECTIVES

This study aimed to further explore the association of night-time sleep and daytime napping with painful TMD.

METHODS

A total of 419 patients (aged 31.88 ± 11.54 years with women forming 85.4%) from a TMD/Orofacial Pain center were enrolled. Patients' sleep conditions were evaluated with the Pittsburgh Sleep Quality Index (PSQI) questionnaire, and information on night-time sleep duration, napping duration and napping frequency was interviewed. TMD was diagnosed according to the Diagnostic Criteria for TMD protocol and stratified into myalgia (muscle pain), arthralgia (joint pain) and combined (muscle and joint pain) subgroups. The severity of TMD was measured with the Fonseca Anamnestic Index (FAI) questionnaire. Restricted cubic spline (RCS) regression models were established to explore relationships between sleep and painful TMD subgroups.

RESULTS

Patients with poor sleep quality (PSQI≥6) had higher FAI scores (median 60, p < .001) and higher proportions of painful TMDs. The myalgia subgroup had higher PSQI scores (median 8, p < .001) than the arthralgia subgroup. The RCS models indicated a non-linear relationship between night-time sleep duration and myalgia (p < .001), which was not observed in arthralgia. However, there were no significant findings concerning napping and painful TMD subgroups.

CONCLUSION

This study found that the association between sleep and TMD is mainly related to painful TMD conditions, which are associated with night-time sleep duration.

Prevalence and associations of temporomandibular disorders in older Brazilian adults

OBJECTIVE

The objective of the study was to estimate the prevalence of temporomandibular disorders (TMD) and describe associations in a representative sample of community-dwelling older Brazilian adults.

BACKGROUND

TMD cause recurrent or chronic pain and dysfunction with substantial impacts on quality of life, but little is known of their occurrence and associated factors among older adults.

MATERIALS AND METHODS

This was a cross-sectional study using data from the second wave of the Brazilian Longitudinal Study of Aging, a nationally representative sample of older Brazilian adults aged 50 or older. The presence of temporomandibular disorder symptoms was measured by the Fonseca Anamnestic Index. Independent variables included sociodemographic characteristics, general health conditions and self-reported oral health measures. The association between the independent variables and TMD symptoms was evaluated using logistic regression models.

RESULTS

Complete information for the variables of interest was available for 9391 individuals. The overall prevalence of TMD symptoms was 18.0% (95% CI 14.4-22.1). Relative to older adults aged 50-59 those in all age categories had lower odds of TMD symptoms. Individuals with depression, pain, sleep problems and self-reported poor general health had higher odds of reporting TMD symptoms. None of the oral health measures were related to TMD.

CONCLUSION

The prevalence of TMD symptoms among Brazilian older adults is associated with demographic and general health conditions, but not with dentition status.

Comorbidities between temporomandibular disorders and somatization in young adults: exploring links with personality, emotional, and sleep disturbances

OBJECTIVE

The comorbidities between temporomandibular disorders (TMDs) and somatization and their associations with personality traits, emotional disorders, and sleep disturbances were investigated.

STUDY DESIGN

Adults aged 18 to 24 years completed an electronic survey encompassing TMD symptoms (5Ts), Patient Health Questionnaire-15, Big Five Personality Inventory-10, Depression Anxiety Stress Scales-21, and Pittsburgh Sleep Quality Index. Data were assessed using non-parametric tests/correlation analysis and logistic regression analysis (α = 0.05).

RESULTS

The sample comprised 365 participants, of whom 22.2% and 19.5% were 5Ts-negative without and with somatization, respectively, and 18.1% and 40.3% were 5Ts-positive without and with somatization, respectively. Significant differences in neuroticism, distress, depression, anxiety, stress, and sleep quality were observed between 5Ts-negative participants with somatization and 5Ts-positive participants with somatization compared with 5Ts-negative participants without somatization and 5Ts-positive participants without somatization. Distress, anxiety, stress, and sleep were moderately correlated with somatic but not TMD symptoms (rs = 0.45-0.52).

CONCLUSIONS

Irrespective of whether they had TMDs, participants with somatization exhibited heightened levels of neuroticism and emotional and sleep disturbances.

Systematic review on effects of experimental orthodontic tooth displacement on brain activation assessed by fMRI

BACKGROUND

Orthodontic treatment is often accompanied by discomfort and pain in patients, which are believed to be a result of orthodontic tooth displacement caused by the mechanical forces exerted by the orthodontic appliances on the periodontal tissues. These lead to change blood oxygen level dependent response in related brain regions.

OBJECTIVE

This systematic review aims to assess the impact of experimental orthodontic tooth displacement on alterations in central nervous system activation assessed by tasked based and resting state fMRI.

MATERIALS AND METHODS

A literature search was conducted using online databases, following PRISMA guidelines and the PICO framework. Selected studies utilized magnetic resonance imaging to examine the brain activity changes in healthy participants after the insertion of orthodontic appliances.

RESULTS

The initial database screening resulted in 791 studies. Of these, 234 were duplicates and 547 were deemed irrelevant considering the inclusion and exclusion criteria. Of the ten remaining potential relevant studies, two were excluded during full-text screening. Eight prospective articles were eligible for further analysis. The included studies provided evidence of the intricate interplay between orthodontic treatment, pain perception, and brain function. All of the participants in the included studies employed orthodontic separators in short-term experiments to induce tooth displacement during the early stage of orthodontic treatment. Alterations in brain activation were observed in brain regions, functional connectivity and brain networks, predominantly affecting regions implicated in nociception (thalamus, insula), emotion (insula, frontal areas), and cognition (frontal areas, cerebellum, default mode network).

CONCLUSIONS

The results suggest that orthodontic treatment influences beyond the pain matrix and affects other brain regions including the limbic system. Furthermore, understanding the orthodontically induced brain activation can aid in development of targeted pain management strategies that do not adversely affect orthodontic tooth movement. Due to the moderate to serious risk of bias and the heterogeneity among the included studies, further clinical trials on this subject are recommended.

The Impact of Sleep Disturbances on Endogenous Pain Modulation: A Systematic Review and Meta-Analysis

The bidirectional relationship between sleep and pain problems has been extensively demonstrated but despite all the accumulating evidence, their shared mechanisms are currently not fully understood. This review examined the association between sleep disturbances, defined as a broad array of sleep-related outcomes (eg, poor quality, short duration, insomnia), and endogenous pain modulation (EPM) in healthy and clinical populations. Our search yielded 6,151 references, and 37 studies met the eligibility criteria. Qualitative results showed mixed findings regarding the association between sleep disturbances and temporal summation of pain (TSP) and conditioned pain modulation (CPM), with poor sleep more commonly associated with decreased pain inhibition in both populations. Quantitative results indicated that such associations were not statistically significant, neither in healthy populations when EPM outcomes were assessed for changes pre-/post-sleep intervention (TSP: .31 [95%CI: -.30 to .92]; P = .321; CPM: .40 [95%CI: -.06 to .85] P = .088) nor in clinical populations when such association was assessed via correlation (TSP: -.00 [95%CI: -.22 to .21] P = .970; CPM: .12 [95%CI: -.05 to .29]; P = .181). For studies that reported results by sex, meta-analysis showed that experimental sleep disturbances impaired pain inhibition in females (1.43 [95%CI: .98-1.88]; P < .001) but not in males (-.30 [95%CI: -2.69 to 1.60]; P = .760). Only one study investigating the association between sleep disturbances and offset analgesia was identified, while no studies assessing spatial summation of pain were found. Overall, this review provides a comprehensive overview of the association between sleep disturbances and EPM function, emphasizing the need for further investigation to clarify specific mechanisms and phenotypic subtypes. PERSPECTIVE: This review shines a light on the association between sleep disturbances and endogenous pain modulation function. Qualitatively, we found a frequent association between reduced sleep quality and impaired pain inhibition. However, quantitatively such an association was not corroborated. Sex-specific effects were observed, with females presenting sleep-related impaired pain inhibition but not males.

Longitudinal patterns of patient-reported sleep disturbances after surgery for lung cancer

PURPOSE

The purpose of this study was to identify longitudinal heterogeneous trajectories of sleep status, adjusted for the effect of pain over time, among patients who had surgery for lung cancer and to quantify how disturbed sleep in the hospital affects functional recovery after discharge.

METHODS

We included patients from a surgical cohort (CN-PRO-Lung 1). All patients reported symptoms using the MD Anderson Symptom Inventory-Lung Cancer (MDASI-LC) daily during postoperative hospitalization. Group-based dual trajectory modeling was used to investigate trajectories of disturbed sleep and pain during the first 7 days of postoperative hospitalization. Cox regression was used to compare the recovery of walking ability between the different sleep trajectories.

RESULTS

Among 421 patients, disturbed sleep trajectories comprised low (31%), moderate (52%), and high (17%) groups. The surgical approach and number of chest tubes were associated with pain, and the number of chest tubes was also associated with sleep disturbances (OR = 1.99; 95% CI: 1.08-3.67). Recovery of walking ability after discharge was significantly slower in the high (median days = 16; 95% CI: 5-NA) and moderate disturbed sleep trajectory groups (median days = 5; 95%CI: 4-6) than in the low group (median days = 3; 95% CI: 3-4).

CONCLUSION

Changes in disturbed sleep among patients with lung cancer followed three distinct trajectories over the first 7 days of hospitalization after surgery. Dual trajectory analyses highlighted the high concordance between specific trajectories of disturbed sleep and pain. Patients at high sleep disturbance and high levels of pain may benefit from appropriate interventions for both symptoms in combination with the patient's surgical approach and the number of chest tubes.

Clinical Phenotypes Supporting the Relationship Between Sleep Disturbance and Impairment of Placebo Effects

Lack of good sleep or insomnia can lead to many health issues, including an elevated risk of cardiovascular disease, obesity, fatigue, low mood, and pain. While chronic pain negatively impacts sleep quality, the relationship between descending pain modulatory systems like placebo effects and sleep quality is not thoroughly known. We addressed this aspect in a cross-sectional study in participants with chronic pain. Placebo effects were elicited in a laboratory setting using thermal heat stimulations delivered with visual cues using classical conditioning and verbal suggestions. We estimated the levels of insomnia severity with the Insomnia Severity Index and the sleep quality with the Pittsburg Sleep Quality Index. The previous night's sleep continuity was assessed as total sleep time, sleep efficiency, and sleep midpoint the night before the experiment. 277 people with chronic pain and 189 pain-free control individuals participated. Participants with chronic pain and insomnia showed smaller placebo effects than those with chronic pain without insomnia. Similarly, poor sleep quality was associated with reduced placebo effects among participants with chronic pain. Clinical anxiety measured by Depression Anxiety Stress Scales partially mediated these effects. In contrast, placebo effects were not influenced by the presence of insomnia or poor sleep quality in pain-free participants. Sleep continuity the night before the experiment did not influence the placebo effects. Our results indicate that participants who experience insomnia and/or poor sleep quality and chronic pain have smaller placebo effects, and that the previous night sleep continuity does not influence the magnitude of placebo effects. PERSPECTIVE: This study examined the relationship between sleep disturbances and experimentally induced placebo effects. We found that individuals with chronic pain who experience insomnia and poor sleep quality demonstrated reduced placebo effects compared to their counterparts with good sleep quality and no insomnia.

Sex differences in descending control of nociception (DCN) responses after chronic orofacial pain induction in rats and the contribution of kappa opioid receptors

Descending control of nociception (DCN), a measure of efficiency of descending pain inhibition, can be assessed in animals by the combined application of test and conditioning noxious stimuli. Evidence from pre-clinical and clinical studies indicates that this mechanism of pain control may differ between sexes and might be impaired in many chronic pain states. However, little is known about sex differences in DCN efficiency in models of acute and chronic orofacial pain. Herein, we first evaluated DCN responses in male and female rats by the applying formalin into the upper lip or capsaicin into the forepaw as the conditioning stimulus, followed by mechanical stimulation (Randall-Selitto) of the hind paw as the test stimulus. The same protocol (i.e., capsaicin in the forepaw followed by mechanical stimulation of the hind paw) was evaluated in male and female rats on day 3 after intraoral incision and on day 15 and 30 after chronic constriction injury of the infraorbital nerve (CCI-ION). Additionally, we assessed the effect of the kappa opioid receptor (KOR) antagonist Norbinaltorphimine (nor-BNI) on DCN responses of female nerve-injured rats. This study shows that naïve female rats exhibit less efficient DCN compared to males. Postoperative pain did not alter DCN responses in female and male rats, but CCI-ION induced loss of DCN responses in females but not in males. Systemic pretreatment with nor-BNI prevented the loss of DCN induced by CCI-ION in female rats. The results reveal sex differences in DCN responses and female-specific impairment of DCN following chronic orofacial pain. Moreover, the findings suggest that, at least for females, blocking KOR could be a promising therapeutic approach to prevent maladaptive changes in chronic orofacial pain.

Dental sleep medicine education among undergraduate dental students in France

INTRODUCTION

Dental sleep medicine (DSM) is an emerging discipline that studies the oral and maxillofacial causes and consequences of sleep-related problems. DSM is of upmost importance given the major medical challenge it represents. Therefore, to verify whether the future generation of dentists would be ready to face this challenge, the main objective of this study was to assess the degree of involvement of the French dental schools in teaching DSM at the undergraduate level.

MATERIALS AND METHODS

All 16 dental schools in France were asked to participate in the study by answering to an online survey concerning the DSM curriculum during the 2018-2019 academic year. The survey was addressed to the head of the dental school and/or to relevant course coordinators and contained 10 questions related to the type, content and amount of DSM teaching to undergraduate dental students.

RESULTS

Nine of the 16 (56.2%) French dental schools responded to the questionnaire. All these nine reported the inclusion of DSM in their undergraduate curriculum. The total average hours dedicated to teaching DSM was 5.6 h (SD 4.2; range 1-15 h). Seven of the 9 dental schools spent most of their DSM curriculum teaching time in the fifth year. All of them reviewed obstructive sleep apnoea and sleep-related bruxism and covered some topics related to therapies for sleep-related breathing disorders, such as the use of oral appliance.

CONCLUSION

The results of this survey showed that, although the average hourly volume is relatively high, the DSM teaching in French dental schools appeared to be non-standardised, heterogeneous and often lacunar. It is therefore essential to develop a common curriculum and implement it in all dental schools to provide undergraduate students a comprehensive and updated teaching in DSM.

Modulatory Processes in Craniofacial Pain States

Pain is a common symptom associated with many disorders affecting the craniofacial tissues that include the teeth and their supporting structures, the jaw, face and tongue muscles, and the temporomandibular joint. Most acute craniofacial pain states are easily recognized and readily treated, but chronic craniofacial pain states (e.g., temporomandibular disorders [TMD], trigeminal neuropathies, and some headaches) may be especially challenging to manage successfully. This chapter provides an overview of the processes that underlie craniofacial pain, with a focus on the pain-modulatory mechanisms operating in craniofacial tissues and in the central nervous system (CNS), including the role of endogenous chemical processes such as those involving opioids. The chapter outlines in particular findings from preclinical studies that have provided substantial information about the neural as well as nonneural (e.g., glial) processes involved in the initiation, transmission, and modulation of nociceptive signals in the trigeminal system, and also draws attention to their clinical correlates. The increased understanding gained from these preclinical studies of how nociceptive signals can be modulated will contribute to improvements in presently available therapeutic approaches to manage craniofacial pain as well as to the development of novel analgesic approaches.

Investigating oral health among US adults with sleep disorder: a cross-sectional study

BACKGROUND

This study aims to investigate the relationship between sleep disorders and oral health outcomes among a representative sample of the United States population.

METHODS

The study sample comprised 6,161 participants who participated in the NHANES 2017-2018, representing a population of 255,939,599. Oral health outcomes were assessed using the Oral Health Questionnaire (OHQ), covering dental pain, periodontal disease, bone loss, emotional perceptions of oral health, and impact on daily life. Sleep disorders were evaluated using questions related to sleep trouble and daytime sleepiness.

RESULTS

Analysis of the NHANES 2017-2018 dataset, revealed notable associations between sleep disorders and oral health outcomes. Individuals with sleep disorders were more likely to report dental pain (19.79% vs. 11.8%), periodontal issues (19.5% vs. 12.25%), and feeling bad or embarrassed about their oral health (21% vs. 12%), compared to those without sleep disorders. Difficulty due to oral health issues was also more prevalent among participants with sleep disorders (32.6% vs. 12.9%). Adjusted models demonstrated that individuals with sleep disorders had a significantly higher likelihood of experiencing oral aches [adjusted odds ratio (aOR) = 1.58 (1.22-2.22)], reporting negative emotions about oral health [aOR = 1.59 (1.06-2.37)], and encountering challenges in school or job performance [aOR = 2.27 (1.47-3.51)], compared to individuals without sleep disorders (refer to Table 3). Other significant covariates affecting oral health outcomes included smoking, income, and education level.

CONCLUSIONS

This study reveals a compelling association between sleep disorders and adverse oral health outcomes in the U.S.

POPULATION

Insomnia is associated with symptoms of central sensitization in patients with painful temporomandibular disorders

BACKGROUND

Central sensitization (CS) and temporomandibular disorder (TMD) are both associated with insomnia. Therefore, the authors aimed to investigate whether insomnia was associated with more symptoms of CS in patients with TMD.

METHODS

In 82 volunteers with TMD, insomnia was clinically assessed, allowing sample stratification according to its presence. The Central Sensitization Inventory questionnaire was self-applied to assess the clinical symptoms of CS.

RESULTS

Participants with insomnia had significantly higher mean (SD) scores of CS according to the Central Sensitization Inventory than participants without insomnia (43.10 [12.57] vs 26.59 [13.66]; P = < .001).

CONCLUSIONS

Insomnia was associated with higher scores of CS symptoms in patients with TMD.

PRACTICAL IMPLICATIONS

Insomnia influences TMD as well as its relationship with CS, and, therefore, it is critical to the clinical management of TMD.

Association Between Pharmacotherapy and Sleep Quality in Patients with Chronic Orofacial and Chronic Body Pain: A Cross-Sectional Study

Purpose

Sleep impairment is associated with many chronic pain disorders. While there is an association between chronic pain and sleep disturbances, little is known about the influence of pharmacotherapy for chronic pain conditions, particularly chronic opioid therapy, on sleep. This study aimed to 1) compare the sleep quality (SQ) in patients with two different pain conditions-chronic body pain and chronic orofacial pain; 2) assess the correlation of SQ and pain intensity; and 3) evaluate the association between pharmacotherapy and SQ.

Patients and Methods

The Pittsburgh Sleep Quality Index (PSQI) was used to measure the SQ in subjects with 1) chronic body pain (n = 100) and 2) chronic orofacial pain (n = 100). The visual analogue scale was applied for pain intensity rating. All subjects were adults recruited at Massachusetts General Hospital, United States. The subjects' demographic data, pain intensity, diagnosis and concurrent use of medications were extracted from their electronic medical records (EMR). Statistical analyses were performed using T-test and Pearson correlation coefficient.

Results

Among 200 subjects (mean age 51.01 ± 15.52 years), 141 (70.5%) were females. PSQI and pain intensity were statistically significantly different between the two groups (p < 0.05 and p < 0.0001, respectively) and higher in subjects with chronic body pain. There was a positive correlation between PSQI and pain intensity (chronic orofacial pain r = 0.3535, p = 0.0004; chronic body pain: r = 0.2247, p < 0.026). PSQI was higher in chronic orofacial pain subjects utilizing opioids and benzodiazepines (PSQI = 15.25).

Conclusion

Chronic pain impairs SQ, which is noticeably worse in subjects with body pain conditions. In addition, pain intensity was correlated with poorer SQ, which in turn was linked to the concomitant use of opioid and benzodiazepine therapy in chronic orofacial pain.

Association of oral health with various work problems: a cross-sectional study of Japanese workers

BACKGROUND

Oral diseases affect quality of life and known to decrease productivity. We examined the impact of oral health status on various types of work problems.

METHODS

This cross-sectional study used data from an internet-based self-report questionnaire survey administered to workers in Japan. Responses to the questionnaire regarding seven types of oral health-related work problems (1. Stress; 2. Lack of focus; 3. Lack of sleep; 4. Lack of energy; 5. Lack of communication due to halitosis; 6. Lack of communication due to appearance; 7. Lack of ability due to dental-related pain) were investigated and statistically analyzed. Explanatory variables were self-reported oral health status, number of teeth, and gum bleeding. To examine the association of oral health with the presence of work problems, logistic regression analysis was used to estimate the odds ratio (OR) and 95% confidence interval (CI). Age, sex, educational attainment, income, the presence of diabetes, and industrial classifications were used as the covariates.

RESULTS

A total of 3,930 workers (mean age: 43.3 (SD = 11.7), 2,057 males and 1,873 females) were included. Overall, a total of 6.2% of workers reported having at least one oral health-related work problem in the past year, whereas 21.8% of those with poor self-reported oral health reported work problems. Workers with poor self-reported oral health were 3.58 (95% CI (1.70-7.56) times higher odds of reporting work problems than those with excellent self-reported oral health.

CONCLUSIONS

Oral health was found to be associated with various work problems. Oral health promotion policies are needed in the workplace.

Sleep Bruxism in Puerperal Women: Data from a Population-Based Survey

OBJECTIVE

To evaluate the self-reported SB prevalence and explore associated risk factors in puerperal women who had given birth in Rio Grande, Southern Brazil.

METHODS

A single, standardized questionnaire was given within the 48 h postpartum period. Self-reported SB was the main outcome investigated. Chi-square test was used to compare proportions, and Poisson regression with robust variance adjustment was used in the multivariate analysis.

RESULTS

A total of 2225 women were included. Only 79 (3.6%) of these reported clenching or grinding their teeth during sleep. Adjusted analysis showed that the higher education level of the mothers (PR = 3.07; 95% CI 1.49-6.28; P = 0.006); living with three or more persons in the household (PR = 0.54; 95% CI 0.34-0.84; P = 0.007); medication intake during pregnancy (PR = 1.68; 95% CI 1.09-2.58; P = 0.017); smoking (PR = 1.93; 1.16-3.23; P = 0.024), or ever smoked (PR = 1.82; 95% CI 0.85-3.90; P = 0.024); severe anxiety (PR = 1.36; 95% CI 0.61-3.02; P = 0.005); and headache upon waking (PR = 4.19; 95% CI 1.95-9.00; P < 0.001) were significantly associated with self-reported SB.

CONCLUSION FOR PRACTICE

Our data pointed towards new factors in a specific group of women that may be relevant for preventing sleep-related behaviors in the pregnancy-puerperal cycle. The higher levels of education, medication intake, smoking or even smoked, severe anxiety, the higher the probability of puerperal woman to self-report SB. The nighttime tooth clenching strongly increased headache upon waking.

Depression, somatization, and sleep disorders as risk factors for temporomandibular disorders development

The objective of this study was to determine the association between temporomandibular disorders (TMD) with depression, somatization and sleep disorders in the city of Maringá, Brazil. A total of 1,643 participants were selected from the Brazilian Unified Health System (SUS). Of these, the test group consisted of 84 participants who had moderate or severe limitations due to TMD pain and the control group consisted of 1,048 participants with no pain. There was a highly statistically significant difference (p<0.001) between cases and controls regarding depression (82.1 versus 37.4%), somatization (84.5 versus 31.4%), and sleep disorders (84.6 versus 36.4%), in moderate to severe levels. The levels of moderate to severe depression, somatization and sleep disorders were significantly higher in TMD subjects with high TMD pain disability. The risk of developing TMD increased 4 to 5 times when the individual has moderate to severe levels of depression, somatization, and sleep disorders. 

The Influence of Sleep Disturbance on Chronic Pain

PURPOSE OF REVIEW

The purpose of this review is to present an overview of common sleep disturbance pathologies and their impact on chronic pain, while examining various factors that are implicit in the relationship between sleep disturbance and chronic pain, including neurobiochemistry, anatomy, and systemic mediators, and reviewing recent and landmark literature.

RECENT FINDINGS

Earlier literature reviews and studies have introduced the bidirectional relationship between sleep disturbance and chronic pain; that is, impaired sleep may worsen chronic pain, and chronic pain causes sleep disturbance. However, more recent reviews and studies seem to show a more associative, rather than causative relationship. There have been recent studies that attempt to determine mechanisms that link sleep disturbance and chronic pain; the results of these studies were more varied, ultimately concluding that there may be a separate, yet-to-be discovered mechanism that shows the causative relationship between sleep disturbance and pain. There are several neurotransmitters that are involved in the mediation of chronic pain and sleep disturbance as separate entities, and some studies have shown that there may be mechanisms that govern both chronic pain and sleep disturbance as a single unit. Other neuroendocrine substances also serve to mediate chronic pain and sleep disturbance. All these substances are found to be associated with various sleep disorders and are also associated with chronic pain symptoms as well. Inflammation plays a role in chronic pain and sleep disturbance, with an increase in inflammatory substances and mediators associated with an increase or worsening in chronic pain symptoms and sleep disorders. The HPA axis plays a role in chronic pain and sleep disorders, influencing pain and sleep pathways through stress response, inflammation, and maintenance of homeostasis. There are several variables that influence both chronic pain and sleep disturbance, and more research into these variables may further our understanding into the complex pathways governing the influence of sleep disturbance on pain, and ultimately to improve treatment for this issue.

Gut Bless Your Pain—Roles of the Gut Microbiota, Sleep, and Melatonin in Chronic Orofacial Pain and Depression

Background. Increased attention has been paid to the gut–brain axis recently, but little is known so far regarding how this translates into pain susceptibility. Aim. The aim of this review is to determine whether gastroenterological disorders and sleep disorders (directly or indirectly) contribute to an increased susceptibility to depression and chronic orofacial pain. Method. A search was performed in the U.S. National Library of Medicine (PubMed) database in order to find studies published before 19 December 2021. We used the following terms: gut microbiome, OR sleep quality, OR melatonin, OR GERD, OR IBS, AND: depression OR chronic pain, in different configurations. Only papers in English were selected. Given the large number of papers retrieved in the search, their findings were described and organized narratively. Results. A link exists between sleep disorders and gastroenterological disorders, which, by adversely affecting the psyche and increasing inflammation, disturb the metabolism of tryptophan and cause excessive microglial activation, leading to increased susceptibility to pain sensation and depression. Conclusions. Pain therapists should pay close attention to sleep and gastrointestinal disorders in patients with chronic pain and depression.

Subjective Sleep Complaints were Associated with Painful Temporomandibular Disorders in Adolescents: the Epidor-Adolescere Study

BACKGROUND

Sleep disturbances in adolescents has received a lot of attention in the literature and it is recognized as a serious health concern. The association between pain and sleep disturbances in adolescents has been extensively studied. However, to the best of our knowledge, there is a lack of studies investigating the association between various subjective sleep variables and painful TMD in adolescents.

OBJECTIVES

to investigate the association between painful TMD and subjective sleep variables in adolescents' non-clinical sample. We conducted a cross-sectional study. TMD was classified according to the RDC/TMD criteria. The Revised Face Scale evaluated TMD pain intensity, and pressure pain thresholds (PPTs) were assessed in trigeminal and extra-trigeminal areas. The subjective sleep variables were assessed according to the Sleep Disturbance Scale for Children and Sleep Behavior Questionnaire.

RESULTS

The final sample consisted of 690 adolescents (12.7±0.76 years), with 16.2% of them presenting painful TMD. Adolescents who frequently reported waking up more than twice per night and feeling tired when awake were more likely to present painful TMD symptoms [OR= 1.7 (95% CI: 1.04-2.90); p=0.034 and OR= 1.6 (95% CI: 1.01-2.48); p=0.046, respectively]. The intensity of TMD pain was negatively associated with sleep quality (p=0.015). Also, PPT values in the trigeminal and extra-trigeminal areas were negatively associated with total sleep time (p= 0.048 and p=0.042, respectively).

CONCLUSIONS

the present results point out the importance of considering sleep complaints associated with painful TMD in adolescents.

Degenerative temporomandibular joint diseases and their relation with sleep and emotional disturbance

OBJECTIVE

The relation of degenerative temporomandibular joint (TMJ) diseases (DJDs) with sleep and emotional disturbance were investigated.

METHODS

CBCT examination of patients (n = 358) with DC/TMD-defined intra-articular temporomandibular disorders was performed and stratified into NN: no DJD and no arthralgia; NA: no DJD with arthralgia; TO: osteoarthrosis; and TR: osteoarthritis. Sleep and emotional disturbance were assessed with the Pittsburgh Sleep Quality Index (PSQI) and Depression Anxiety Stress Scale-21 (DASS-21). Data were evaluated using non-parametric and multivariate logistic regression analyses (α = 0.05).

RESULTS

Distributions of NN, NA, TO, and TR groups were 23.2%, 27.1%,19.0%, and 30.7%, respectively. No significant differences in total-PSQI/DASS scores were detected among the four groups. The presence of pain and stress predicted poor quality sleep with odds ratios of 10.75 and 1.07, accordingly.

CONCLUSION

Sleep quality was affected more by arthralgia and stress than the presence of TMJ DJDs.

Relevance of Sleep Disturbances to Orthopaedic Surgery: A Current Concepts Narrative and Practical Review

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Sleep disturbances can increase the risk of falls and motor vehicle accidents and may reduce bone density.

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Poor sleep can lead to worse outcomes after fracture, such as chronic pain and delayed recovery.

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Orthopaedic surgeons can play an important role in the screening of sleep disorders among their patients.

Impact of the COVID-19 Pandemic on Stress, Sleep, and Oral Health in University Students

Background: The COVID-19 pandemic, a disease caused by Sars-CoV-2, has become a worldwide stressor, especially as it represents a new viral infection, which spreads quickly and easily, without prior knowledge about vaccination, and absence, to this moment, of a medication that is totally effective against the disease.

Objective: The aim of this observational study was to provide a general evaluation, through a questionnaire applied to students in the health field of the Federal University of Rio de Janeiro, on the psychological impacts and behavioral changes generated by the COVID-19 pandemic on oral health, especially the triggering or exacerbation of bruxism and temporomandibular disorders (TMD).

Methods: In order to verify the impacts of the pandemic on the health of UFRJ healthcare students, a non-randomized survey was performed with 370 students.

Results: It was found that 72% of the students had their sleep routine altered, 65% had greater difficulty in keeping their spirits up, there was a statistically significant increase in emotional stress, headaches, and daytime teeth clenching.

Conclusion: It was possible to conclude that the outbreak of COVID-19 resulted in psychological, physiological and behavioral impacts on students.

Determination of the temperature causing a nociceptive response in the tail of albino BALB/c mice

INTRODUCTION

Designs for determining nociceptive response in rodents are of great use in neurology and experimental neuroscience. Immersing mice's tails in warm water is one of the most widely used procedures to evaluate this response; however, a wide range of temperatures are used in different studies. Knowing the temperature that produces a powerful nociceptive response in the tail of BALB/c mice is extremely useful.

METHODS

Eight 2-month-old male BALB/c mice were used. A 14-cm high beaker was filled with water up to 13cm. The animals' tails were immersed in the container with a starting temperature of 36°C. The water temperature was raised in 1°C increments until we identified the temperatures that produced nociceptive responses. That response was determined by counting the time taken before the mouse shook its tail to remove it from the water.

RESULTS

Six of the 8 mice began shaking their tails at the temperature of 51°C. All animals removed their tails from the water at the temperatures of 54°C, 55°C, and 56°C, taking a mean time of 8.54, 7.99, and 5.33seconds, respectively. ANOVA applied to the response times for each of the 3 temperatures indicated revealed a value of F=2.8 (P=.123).

CONCLUSIONS

The response time was statistically similar for the temperatures of 54°C, 55°C, and 56°C; however, the data were less dispersed for the latter temperature.

Subjective sleep quality and temporomandibular disorders: Systematic literature review and meta-analysis

STUDY OBJECTIVES

To assess the general subjective sleep quality in individuals with and without TMD, and its distribution among the TMD diagnostic groups.

METHODS

A systematic review search was performed in Pubmed/MEDLINE, Embase, LILACS, Web of Science, SciELO, CINAHL and Cochrane Central as well as in the grey literature. Observational studies published since 1992 which used either the DC/TMD or RDC/TMD for TMD diagnosis and either the PSQI, SAQ or ESS questionnaires for sleep assessment were included. Articles selected for meta-analysis underwent quality, heterogeneity and publication bias evaluation.

RESULTS

A total of 1071 articles were found by online search, and 10 articles were added manually. For full-text reading, 138 papers were selected. Thirty-six articles were included in the final review, and 19 in the meta-analysis (PSQI only). Subjective sleep quality was shown to be associated with all RDC/TMD or DC/TMD Axis I diagnostic groups: muscle disorders, arthralgia/osteoarthritis/osteoarthrosis and disk displacements; with the highest association in the first two groups, and the lowest in the last one. A 4.45 times increased odds ratio of TMD prevalence was found for individuals who presented poor subjective sleep quality.

CONCLUSION

Subjective sleep quality should be considered in the management of TMD.

Conducive environments reduce sleep disturbances and improve sleep quality: a quality improvement project

AIM

The current implementation project aimed to improve patients' sleep quality in a hospital by implementing targeted interventions to reduce sleep disturbances.

METHODS

The Silent Night project was implemented in two general units of an academic tertiary hospital. The project comprised three phases: preimplementation, implementation, and postimplementation. Patient surveys were administered to obtain patients' perspectives on the sources of noise disturbances at night. Noise-monitoring machines were installed in two wards to obtain objective data on noise levels at night. Concurrently, data were collected on noise-generating activities that were observed.

RESULTS

The overall quality of sleep reported by patients improved by 17% (from 73.5 to 88.9%). Patients' survey reported reduced noise disturbances from direct care activities, environmental noise and medical equipment alarms. The mean noise level in the orthopedics unit reduced significantly from 57.04 to 55.22 dB with a corresponding decrease in noise generating activities by 60% (from 362 to 144). In the geriatric unit, the mean noise level increased from 51.36 to 53.12 dB but is within the National Environmental Agency's permissible noise level of 55 dB even though the noise generating activities reduced significantly by 92.2% (from 954 to 74).

CONCLUSION

The 'Silent Night' project has successfully reduced noise disturbances generating from environment and nursing care activities and improved patients' sleep quality in the hospital. Sharing sessions regarding sources of noise and the 'Silent Night' poster promoted the awareness of noise disturbances in healthcare professionals, visitors, and patients.

Trigeminal sensory nerve patterns in dentine and their responses to attrition in rat molars

OBJECTIVE

Our goal was to define trigeminal nerve ending quantities and patterns in rat molar dentine, their responses to attrition (tooth wear), and their associated odontoblasts and connections with pulpal plexuses.

DESIGN

Trigeminal ganglia were labeled for axonal transport of ³H-proteins to dentinal nerve endings in male rats (3-13 months old). Autoradiography detected radio-labeled dentinal tubules as indicators of nerve ending locations. Quantitative morphometry was done (ANOVA, t-tests), and littermates were compared for attrition and innervation.

RESULTS

There were six dentinal patterns, only two of which had an associated neural plexus of Raschkow and cell-free zone (Den-1, Den-2). Other nerves entered dentin from bush-like endings near elongated odontoblasts (Den-B), as single fibers (Den-X), as networks in predentine (PdN), or as single fibers in tertiary dentine at cusp tips (Den-S). There were at least 186,600 innervated dentinal tubules within the set of three right maxillary molars of the best-labeled rat, and similar densities were found in other rats. Attrition levels differed among cusps and in littermates (t-test p < 0.02-0.0001), but the matched right/left cusps per rat were similar. Innervations of tertiary and enamel-free dentine (Den-S, Den-X) were preserved in all rats. Den-B and Den-2 coronal patterns were unchanged unless displaced by dentinogenesis. Den-1 losses occurred in older cusps, while Den-2 patterns increased near cervical and intercuspal odontoblasts.

CONCLUSIONS

The extensive molar dentinal innervation had unique distributions per rat per cusp that depended on region (buccal, middle, palatal) and attrition, but only two of six patterns connected to a plexus of Raschkow.

Study on the association between sleep disorders versus oral health related variables

Background

To study the association between sleep quality and oral health related variables, which still have conflicts in the literature.

Material and Methods

This was a population-based case-control study between subjects with versus without sleep disorders from the Brazilian Public Health System (SUS), city of Maringá (N=1,643). Subjects answered self-reported questionnaires: a) Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), b) Sleep Assessment Questionnaire (SAQ) and c) North York Dental Health Survey (NYDHS).

Results

No significant difference was found for gender, marital status, or income; however, non-Caucasians, people with lower levels of education, and those between 20 to 50 years old had worse scores of sleep disorders in the SAQ. Self-perceived oral health, masticatory capacity to eat foods, and gingival bleeding was significantly worse among subjects with self-reported sleep disorders. Self-reported tooth loss, edentulism and use of removable partial dentures (with clasps) or complete dentures showed no significant difference between groups. Self-reported sleep disorder subjects presented significantly higher prevalence of both self-reported tooth and TMJ pain.

Conclusions

It can be concluded that individuals with self-reported sleep disorders presented worse self-perceived oral health for most studied variables.

Key words:Oral health, case control study, sleep; review, gingivitis, periodontitis, tooth loss.

Temporomandibular disorder severity and diagnostic groups: Their associations with sleep quality and impairments

OBJECTIVES

This study evaluated the impact of TMD severity on sleep quality and established the associations between TMD diagnostic groups/pain subtypes and sleep impairments.

METHODS

A total of 1151 patients from a tertiary Dental Hospital were screened for eligibility. Consenting subjects who met the inclusion criteria were directed to complete a general/health questionnaire, the Fonseca Anamnestic Index (FAI), Diagnostic Criteria for Temporomandibular disorders (DC/TMD) Symptom Questionnaire, and Pittsburgh Sleep Quality Index (PSQI) at their intake visit. Patients who screened positive for TMDs with the FAI were subjected to a protocolized physical examination and TMD diagnostic groups/subtypes were subsequently derived based on the DC/TMD "diagnostic tree" and algorithms. Statistical analyses were conducted using non-parametric methods and logistic regression (α = 0.05).

RESULTS

The final sample consisted of 845 subjects with TMDs and 116 TMD-free controls. The mean age of the TMD and TMD-free subjects were 33.17 ± 13.55 and 31.66 ± 9.50 years. Subjects with severe and moderate TMDs had significantly greater global PSQI scores than those with mild and no TMDs (p < 0.001). Those with pain-related, intra-articular, and combined TMDs reported significantly poorer sleep quality than those with no TMDs (p < 0.001). Moreover, subjects with myalgia and myalgia plus arthralgia presented significantly greater sleep impairments than their counterparts with intra-articular disorders (p < 0.001). Multivariate logistic regression indicated that pain-related (OR = 3.23; CI = 1.69-6.14) and intra-articular TMDs (OR = 1.91; CI = 1.15-3.16) were most related to poor sleep.

CONCLUSIONS

Sleep quality worsened with increasing TMD severity and the presence of painful and intra-articular TMDs increased the likelihood of poor sleep.

The Medial Thalamus Plays an Important Role in the Cognitive and Emotional Modulation of Orofacial Pain: A Functional Magnetic Resonance Imaging-Based Study

The thalamus plays a critical role in the perception of orofacial pain. We investigated the neural mechanisms of orofacial pain by exploring the intrinsic functional alterations of the thalamus and assessing the changes in functional connectivity (FC) between the thalamic subregions with significant functional alterations and other brain regions in orofacial pain using the seed-based FC approach. There were 49 participants in the orofacial pain group and 49 controls. Orofacial pain was caused by orthodontic separators. The resting-state functional magnetic resonance imaging data of the two groups were analyzed to obtain the fractional amplitude of low-frequency fluctuations (fALFF) of the thalamus; the thalamic subregions with significant fALFF abnormalities were used as seeds for FC analysis. Student's t-tests were used for comparisons. Pearson's correlation analysis was performed using SPM software. Forty-four participants with orofacial pain (mean age, 21.0 ± 0.9 years; 24 women) and 49 age- and sex-matched controls (mean age, 21.0 ± 2.6 years; 27 women) were finally included. Compared with the control group, the orofacial pain group demonstrated the following: (1) increased function in the dorsal area of the thalamus and decreased function in the medial thalamus; (2) decreased FC between the medial thalamus and 12 brain regions (p < 0.05, family-wise error corrected, voxel > 100); and (3) potential positive and negative correlations between the medial thalamus-seeded FC and visual analog scale score changes (p < 0.05, AlphaSim corrected). The findings show that the medial and dorsal thalami play important roles in orofacial pain perception, and that the medial thalamus likely plays an important role in the cognitive and emotional modulation of orofacial pain.

Comparison of emotional disturbance, sleep, and life quality in adult patients with painful temporomandibular disorders of different origins

OBJECTIVES

This study compared the differences in emotional disturbance, sleep, and life quality among adult patients with temporomandibular (TMD) muscle and/or joint pain.

MATERIALS AND METHODS

The study involved an analytical cross-sectional design. A total of 420 consecutive patients diagnosed with pain-related TMDs based on the Diagnostic Criteria for TMDs (DC/TMD) were recruited from a TMD referral centre and stratified into three groups, namely muscle pain (MP; n = 50), joint pain (JP; n = 329), and combined muscle-joint pain (CP; n = 41). Emotional disturbance, sleep quality, and oral health-related quality of life (OHRQoL) were assessed with the Depression, Anxiety, and Stress Scale-21 (DASS-21), Pittsburgh Sleep Quality Index (PSQI), and Oral Health Impact Profile-TMDs (OHIP-TMDs) respectively. Statistical analyses were performed using the chi-square test, one-way ANOVA, and Pearson's correlation (p < 0.05).

RESULTS

Mean age for the three pain groups (females = 349; males = 71) ranged from 37.15 ± 14.91 to 38.60 ± 14.37 years (p = 0.973). Ranking of depression, anxiety, and stress scores was as follows: CP > MP > JP. Significant differences in emotional disturbances were observed (p < 0.001). CP patients had significantly poorer sleep quality than those with JP (p = 0.004). Moreover, OHRQoL was also significantly more impaired as compared to both MP (p = 0.006) and JP (p < 0.001) patients. Correlations between global PSQI and OHIP-TMDs scores were weak to moderate (r_s = 0.30-0.47).

CONCLUSIONS

Patients with combined muscle-joint pain presented higher levels of emotional disturbance than those with only MP or JP. They also had significantly poorer sleep quality and lower OHRQoL.

CLINICAL RELEVANCE

Emotional and sleep health must be considered in the management of painful TMDs.

Clinical variables associated with the presence of articular pain in patients with temporomandibular joint clicking

OBJECTIVE

To study and estimate the impact of clinical, somatosensory, and psychosocial variables associated with the concomitant presence of temporomandibular joint (TMJ) pain in patients with TMJ clicking.

MATERIALS AND METHODS

Ninety-three individuals composed the sample: patients with painful TMJ clicking (n = 47) and patients with painless TMJ clicking (n = 46). Four categories of data were evaluated: clinical features (gender, maximal interincisal distance (MID), side of complaint, age); bruxism (sleep bruxism (SB), awake bruxism (AB)); somatosensory (mechanical pain threshold (MPT), wind-up ratio (WUR), pressure pain threshold (PPT), conditioned pain modulation (CPM)); and psychosocial (Pittsburgh Sleep Quality Index (PSQI), pain vigilance and awareness questionnaire (PVAQ), Pain Catastrophizing Scale (PCS), Tampa Scale for Kinesiophobia for Temporomandibular Disorders (TSK/TMD), Oral Behaviors (OBs)).

RESULTS

Female gender, AB, WUR, CPM, PSQI, PCS, and OBs significantly (p < 0.05) increased the chance of the concomitant presence of TMJ pain in patients with TMJ clicking. On the other hand, MID, MPT, and PPT significantly (p < 0.05) decreased this chance. The other variables had no association.

CONCLUSION

It can be concluded that being a woman, having AB, hyperalgesia in WUR, less efficient CPM, poor sleep quality, pain catastrophizing, and harmful OBs significantly increased the chance of the concomitant presence of TMJ pain in patients with TMJ clicking. In the opposite, high figures of MID, MPT, and PPT decreased the chance.

CLINICAL RELEVANCE

Most patients with TMJ clicking usually postpone seeking treatment until the clicking truly disturbs or there is a concomitant presence of TMJ pain. Understanding the variables associated with this concomitance can be important in clinical practice.

Association between craniofacial pain complaints, somatoform symptoms and chronic diseases

OBJECTIVE

This case-control study aimed to investigate associations between craniofacial pain complaints, somatoform symptoms and chronic diseases.

DESIGN

306 subjects were included in this study (174 patients and 132 healthy subjects). The evaluation consisted of demographic data, number of functional and nonfunctional chronic diseases, medications, somatoform symptoms (xerostomia, dry mucosa, numbness, gastrointestinal complaints), and pain complaints with associated characteristics (number of pain areas, sensation of tired face, bruxism, sleep disturbances, masticatory musculoskeletal evaluation). Statistical analysis included descriptive data, tested with chi-square, Fisher's exact, nonparametric Kolmogorov-Smirnoff, Student's t-test, Pearson's coefficient, two-steps cluster classification, multivariate linear and LASSO regressions.

RESULTS

Functional disorders were prevalent in 111 (63.8 %) patients with facial pain. They were taking more medication (p < 0.001) and had more sleep disturbances (p < 0.001), higher xerostomia scores (p < 0.001) and more gastrointestinal complaints (p < 0.001) than controls. There was a positive correlation between the functional score and the number of cranial areas with headache (R² = 0.266, <0.001). The regression models for facial pain (R² = 0.632), craniofacial pain (R² = 0.623) and headache (R² = 0.252) showed significant dependency of functional disorders (p < 0.001).

CONCLUSION

craniofacial pain was associated with functional diseases and somatoform symptoms. This association needs further investigation to understand the role of those disorders in craniofacial pain, considering that pain complaints are common somatoform and functional symptoms.

The face of Dental Sleep Medicine in the 21st century

It becomes increasingly clear that some sleep disorders have important diagnostic and/or management links to the dental domain, hence the emergence of the discipline ‘Dental Sleep Medicine’. In this review, the following topics are discussed: 1. the reciprocal associations between oro‐facial pain and sleep; 2. the associations between sleep bruxism and other sleep‐related disorders; 3. the role of the dentist in the assessment and management of sleep bruxism; and 4. the dental management of obstructive sleep apnoea. From these topics' descriptions, it becomes clear that the role of the dentist in the recognition and management of sleep‐related oro‐facial pain, sleep bruxism and obstructive sleep apnoea is large and important. Since many dental sleep disorders can have severe consequences for the individual's general health and well‐being, it is imperative that dentists are not only willing to take on that role, but are also able to do so. This requires more attention for Dental Sleep Medicine in the dental curricula worldwide, as well as better postgraduate training of dentists who are interested in specialising in this intriguing domain. This review contributes to increasing the dental researcher's, teacher's and care professional's insight into the discipline ‘Dental Sleep Medicine’ as it has taken shape in the 21st century, to the benefit of all patients suffering from dental sleep disorders.

The Evolution of Neuroscience as a Research Field Relevant to Dentistry

The field of neuroscience did not exist as such when the Journal of Dental Research was founded 100 y ago. It has emerged as an important scientific field relevant to dentistry in view of the many neurally based functions manifested in the orofacial area (e.g., pain, taste, chewing, swallowing, salivation). This article reviews many of the novel insights that have been gained through neuroscience research into the neural basis of these functions and their clinical relevance to the diagnosis and management of pain and sensorimotor disorders. These include the neural pathways and brain circuitry underlying each of these functions and the role of nonneural as well as neural processes and their "plasticity" in modulating these functions and allowing for adaptation to tissue injury and pain and for learning or rehabilitation of orofacial functions.

Analgesic effects of the CTK 01512-2 toxin in different models of orofacial pain in rats

BACKGROUND

Orofacial pain is clinically challenging, having therapeutic failures and side effects. This study evaluated the antinociceptive activities of the CTK 01512-2 toxin, the TRPA1 channel antagonist, and the selective inhibitor of the N-type voltage-gated calcium channels (N-type VGCC), in different pain models.

MATERIALS AND METHODS

The trigeminal ganglia were stimulated in vitro with capsaicin. The in vivo models received subcutaneous (sc) injections of formalin into the upper lip of the rats, Freund's Complete Adjuvant (FCA) into the temporomandibular joint (TMJ), and infraorbital nerve constrictions (IONC). CTK 01512-2 at concentrations of 30, 100, and 300 pmol/site, intrathecally (ith), and MVIIA at 10, 30, and 100 pmol/site in the formalin test, guided the doses for the models. The glutamate levels in the CSF of the rats that were submitted to IONC were analyzed.

RESULTS

CTK 01512-2 decreased the nociceptive behavior in the inflammatory phase of the formalin test (65.94 ± 7.35%) and MVIIA in the neurogenic phase (81.23 ± 3.36%). CTK 01512-2 reduced facial grooming with FCA in the TMJ (96.7 ± 1.6%), and in the IONC neuropathy model, it decreased heat hyperalgesia (100%) and cold hyperalgesia (81.61 ± 9.02%). The levels of glutamate in the trigeminal ganglia in vitro (81.40 ± 8.59%) and in the CSF in vivo (70.0 ± 9.2%) were reduced.

CONCLUSIONS

The roles of TRPA1 in pain transduction and the performance of CTK 01512-2 in the inhibition of the N-type VGCCs were reinforced. This dual activity may represent an advantage in clinical treatments.

Functional, physical and psychosocial impact of Temporomandibular Disorders in adolescents and young adults

Background

This community-based study investigated the functional, physical and psychosocial impact of Temporomandibular Disorders (TMDs) in adolescents and young adults. It also determined the discriminative capacity of a TMDs-specific oral health related quality of life (OHRQoL) instrument and compared three formats of appraising OHRQoL data.

Material and Methods

Subjects were recruited from a local Polytechnic. The presence of TMDs was established with the Fonseca Anamnestic Index (FAI), whilst TMDs-specific OHRQoL was evaluated with the Oral Health Impact Profile–TMDs (OHIP-TMDs). Demographic information, FAI and OHIP-TMDs responses were gathered with an on-line questionnaire. Data was analysed using Mann-Whitney U-test, chi-square test and Spearman’s rho correlation with significance level set at 0.05.

Results

Data from a total of 244 participants were compiled and examined. The “no TMDs” (NT) group consisted of 140 subjects (119 females; 21 males) with a mean age of 20.41±3.29 years, while the “with TMDs” (WT) group composed of 104 subjects (88 females; 16 males) aged 19.82±3.04 years. Significant differences in median severity scores were observed between subjects with and without TMDs for all OHIP-TMDs domains and total OHIP (p values < 0.001). For appraisal of extent and prevalence, significant differences were again observed (p values < 0.05) with the exception of the functional limitation and handicap domains.

Conclusions

TMDs impacted physical and psychosocial well-being of adolescents and young adults. OHIP-TMDs, preferably appraised by severity, extent and prevalence, was able to discriminate between subjects with and without TMDs. It holds promise as a TMDs-specific OHRQoL instrument for epidemiological studies.

Key words:Temporomandibular Disorders, Oral health, Quality of life, Biopsychosocial.

Chewing causes rapid changes in immunoreactive nerve patterns in rat molar teeth: Implications for dental proprioception and pain

OBJECTIVE

This study tests the hypothesis that normal use of teeth (chewing) causes changes in immunoreactive-(IR) patterns for endings of large Aβ and CGRP axons in rat molar cusps.

DESIGN

First, a new paradigm to test chewing in adult male rats was developed. Then IR patterns for large dental axons were analysed for a calcium-binding protein, parvalbumin (PV), heavy neurofilament protein-200 (NFP), and vesicle-release molecule synaptophysin (SYN) that all typify large dental axons and proprioceptors for comparison with endings of CGRP-IR neuropeptide axons. The behavior groups were: (1) daytime sleeping/fasting (Group:SF); (2) brief feeding after 8-11 h of daytime sleeping/fasting (Group:SF-C); (3) normal nocturnal feeding (Group:N); (4) nocturnal fasting (Group:NF); (5) brief feeding/chewing after nocturnal fasting (Group:NF-C).

RESULTS

Nerve endings with NFP-, PV-, or SYN-IR were lost or altered in pulp and dentin in all chewing groups. Other endings with CGRP-IR were near those with PV-, NFP- and SYN-IR at the pulp-dentin border and in dentin, and they also lost immunoreactivity in all chewing groups. The special beaded regions along the crown pulp/dentin borders lost neural labeling in all chewing groups. Nerves of molar roots and periodontal ligament were not changed.

CONCLUSIONS

Rapid neural reactions to chewing show extensive, reversible, non-nociceptive depletions of crown innervation. Those changes were rapid enough to occur during normal feeding followed by recovery during rest. The new dental paradigm related to chewing and fasting allows dissection of intradental proprioceptive-like mechanisms during normal tooth functions for comparison with nociceptive and mechanosensitive reactions after injury or inflammation.

Intra-periaqueductal gray matter administration of orexin-A exaggerates pulpitis-induced anxiogenic responses and c-fos expression mainly through the interaction with orexin 1 and cannabinoid 1 receptors in rats

Different types of trigeminal pains are frequently associated with psychophysiological concerns. Orexin-A and orexin 1 receptor (OX1R) are involved in modulation of both trigeminal pain and anxiety responses. Ventrolateral periaqueductal gray matter (vlPAG), a controlling site for nociception and emotion, receives orexinergic inputs. Here, the role of vlPAG OX1Rs and their interaction with cannabinoid 1 (CB1) receptor was evaluated in anxiety-like behavior following capsaicin-induced dental pulp pain. Rats were cannulated in the vlPAG and orexin-A was injected at the doses of 0.17, 0.35 and 0.51 μg/rat prior to the induction of pain. The elevated plus maze (EPM) and open field (OF) tests were used for assessing the anxiety responses. In addition, the induction of c-fos, in the vlPAG, was investigated using immunofluorescence microscopy. Capsaicin-treated rats displayed significantly higher anxiogenic behavior on EPM and OF tests. Pretreatment with orexin-A (0.51 μg/rat) attenuated capsaicin-mediated nociception, while exaggerated anxiogenic responses (p < 0.05). In addition, orexin-A effects were diminished by the administration of OX1R (SB-334867, 12 μg/rat) and cannabinoid 1 (AM251, 4 μg/rat) receptor antagonists. Intradental capsaicin induced a significant increase in c-fos expression in the vlPAG that was exaggerated by orexin-A (0.51 μg/rat). Blockage of OX1R and CB1 receptors attenuated the effect of orexin-A on c-fos expression in capsaicin-treated rats. In conclusion, the data suggest that manipulation of OX1R and CB1 receptors in the vlPAG alters capsaicin-evoked anxiety like behaviors and c-fos induction in rats.