Prediction of duloxetine efficacy in addition to self-management in painful temporomandibular disorders: A randomised, placebo-controlled clinical trial.

BACKGROUND: Conditioned pain modulation (CPM) is a potential predictor of treatment response that has not been studied in temporomandibular disorders (TMD). OBJECTIVES: We conducted a randomised, double-blind, placebo-controlled trial (RCT) of duloxetine in addition to self-management (SM) strategies to investigate its efficacy to reduce pain intensity in painful TMD patients. Moreover, we investigated whether baseline CPM would predict the duloxetine efficacy to reduce TMD pain intensity. METHODS: Eighty participants were randomised to duloxetine 60 mg or placebo for 12 weeks. The primary outcomes were the change in the pain intensity from baseline to week-12 and CPM-sequential paradigm at baseline. Safety, physical and emotional functioning outcomes were also evaluated. RESULTS: Of 80 participants randomised, 78 were included in intention-to-treat analysis. Pain intensity decreased for SM-duloxetine and SM-placebo but did not differ between groups (p = .82). A more efficient CPM was associated with a greater pain intensity reduction regardless of the treatment group (p = .035). Physical and emotional functioning did not differ between groups, but adverse events (p = .014), sleep impairment (p = .003) and catastrophizing symptoms (p = .001) were more prevalent in SM-duloxetine group. CONCLUSION: This study failed to provide evidence of a beneficial effect of adding duloxetine to SM strategies for treatment of painful TMD. Nonetheless, this RCT has shown the feasibility of applying pain modulation assessment to predict short-term treatment response in painful TMD patients, which confirms previous finds that CPM evaluation may serve a step forward in individualising pain treatment.

Secondary bruxism: A valid diagnosis or just a coincidental finding of additional masticatory muscle activity? A narrative review of literature.

INTRODUCTION: Bruxism is defined as a repetitive masticatory muscle activity that can manifest it upon awakening (awake bruxism-AB) or during sleep (sleep bruxism-SB). Some forms of both, AB and SB can be associated to many other coexistent factors, considered of risk for the initiation and maintenance of the bruxism. Although controversial, the term 'secondary bruxism' has frequently been used to label these cases. The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques, however, are important factors to be considered when judging the literature findings. The use (and abuse) of drugs, caffeine, nicotine, alcohol and psychoactive substances, the presence of respiratory disorders during sleep, gastroesophageal reflux disorders and movement, neurological and psychiatric disorders are among these factors. The scarcity of controlled studies and the complexity and interactions among all aforementioned factors, unfortunately, does not allow to establish any causality or temporal association with SB and AB. The supposition that variables are related depends on different parameters, not clearly demonstrated in the available studies. OBJECTIVES: This narrative review aims at providing oral health care professionals with an update on the co-risk factors and disorders possibly associated with bruxism. In addition, the authors discuss the appropriateness of the term 'secondary bruxism' as a valid diagnostic category based on the available evidence. CONCLUSION: The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques found in many studies preclude any solid and convincing conclusion on the existence of the 'secondary' bruxism.

Divergence between confidence and knowledge of endodontists regarding non-odontogenic pain.

INTRODUCTION: This study aimed to assess the self-reported levels of confidence and knowledge related to non-odontogenic pain among a group of Brazilian endodontists. METHODOLOGY: A total of one hundred and forty-six endodontists affiliated with the Brazilian Society of Endodontics participated in the survey. The questionnaire, distributed via email or WhatsApp, contained inquiries designed to gauge self-perceived confidence and knowledge concerning non-odontogenic pain. The practitioners were categorized into four groups based on their self-reported familiarity with various orofacial pain types, classified as either sufficient or insufficient, and on their engagement in ongoing educational programs related to orofacial pain. Data were analyzed by Chi-Square Test and Fischer's exact test (p<0.05). RESULTS: Overall, self-reported confidence about non-odontogenic pain was high, especially for endodontists who considered their knowledge about orofacial pain sufficient, regardless of whether they had (71.1% - 97.8%) or not (35.7% - 96.4%) been continuously involved in education courses on orofacial pain. In general, self-reported knowledge about non-odontogenic pain was insufficient (0% - 42%), except in the question about how they would act in cases of pain that persists beyond the normal healing time after an endodontic procedure (70.6% - 81.9%). In general, endodontists are confident in their diagnosis and treatment of non-odontogenic pain. Nonetheless, this confidence did not correlate with a commensurate knowledge depth of. Thus, specialization courses in endodontics should highly consider training and qualifying these professionals in the diagnosis of non-odontogenic pain.

Influence of awake bruxism behaviors on fatigue of the masticatory muscles in healthy young adults.

The present cross-sectional study aimed to analyze the relationship between awake bruxism and fatigue of masticatory muscles in healthy young adults. For this purpose, 121 graduate students participated in this study. Frequency of awake bruxism was collected for 7 consecutive days by ecological momentary assessment (EMA) using an online survey (mentimeter). Muscle fatigue was tested one day after EMA assessment, which consisted of voluntarily and continuously clenching at 30% (kgf/cm2) of maximum bite force (MBF) until exhaustion. The percentage of change in MBF after the clenching task, as compared to the MBF before the clenching task was measured. The average frequency of awake bruxism was 45.5% during 7 days. Sustained clenching resulted in a significant reduction in MBF values in the total sample (p < 0.05). Nevertheless, no significant correlation was found between frequency of awake bruxism behaviors and percent of change in MBF and endurance time during the fatigue test. Therefore, it can be concluded that young healthy adults present a relatively high frequency of awake bruxism behaviors that do not seem to impact the degree of masticatory muscle fatigue.

Experimental pain thresholds and psychosocial features across menstrual cycle in myofascial orofacial pain compared to healthy individuals: cross-sectional study / Limiares de dor experimental e características psicossociais ao longo do ciclo menstrual na dor miofascial orofacial em comparação com indivíduos saudáveis: estudo transversal

ABSTRACT BACKGROUND AND OBJECTIVES: The hormonal impact on pain perception during the menstrual cycle is a major focus of study, and further elucidation in temporomandibular disorders (TMD) field is necessary. Thus, this cross-sectional study evaluated experimental pain thresholds, psychosocial features, and clinical pain report on TMD women across menstrual cycle versus healthy controls. METHODS: A total of 220 women's clinical files were screened, with 80 selected and divided into control group (healthy individuals, n=40) and TMD group (myofascial pain, n=40). Regarding the menstrual cycle phases, the files were divided into Pre-Luteal and Luteal. The Perceived Stress Scale (PSS), Pain Catastrophizing Scale (PCS), Mechanical Pain Threshold (MPT), Wind-up (WUR), Pressure Pain Threshold (PPT), Conditioned Pain Modulation (CPM) and Visual Analogue Scale (VAS) were analyzed at a 5% significance level, by Two-Way ANOVA test and post hoc Tukey test. RESULTS: PSS and PCS were significantly different between TMD and control group (p<0.001), regardless of menstrual cycle. Healthy individuals in the Luteal phase presented higher MPT values compared to the other phases (p<0.001). PPT showed significant difference across menstrual phases (p=0.022), but no differences in multiple comparisons. VAS values showed no difference between menstrual cycle phases (p=0.376). CONCLUSION: Finally, healthy individuals in the Luteal phase have higher MPT and PPT values on the orofacial region. Pain report in patients with TMD showed no difference throughout the menstrual cycle, showing that small alterations on experimental pain thresholds may not be clinically relevant. The presence of chronic pain seems to be more related to psychosocial features than hormonal fluctuations.

RESUMO JUSTIFICATIVA E OBJETIVOS: O impacto do ciclo menstrual na percepção da dor é um foco importante de estudo, sendo necessária uma maior elucidação na disfunção temporomandibular (DTM). Assim, este estudo transversal avaliou limiares de dor experimental, características psicossociais e relatos de dor em mulheres com DTM ao longo do ciclo menstrual, comparadas com controles saudáveis. MÉTODOS: 220 prontuários de mulheres foram analisados, sendo 80 selecionados para os grupos de controle (saudáveis, n=40) e DTM (dor miofascial, n=40). Nas fases do ciclo menstrual, as pacientes foram divididas nas categorias Pré-Luteal e Luteal. Os instrumentos Escala de Estresse Percebido (PSS), Escala de Pensamentos Catastróficos (PCS), Limiar de Dor Mecânica (MPT), Wind-up Ratio (WUR), Limiar de Dor à Pressão (PPT), Modulação Condicionada da Dor (CPM) e Escala analógica visual (EAV) foram analisados com nível de significância de 5%, pelos testes ANOVA de dois fatores e Tukey post hoc. RESULTADOS: As escalas PSS e PCS foram significativamente diferentes entre os grupos DTM e controle (p<0,001), independentemente do ciclo menstrual. Indivíduos saudáveis na fase luteal apresentaram MPT maior em comparação com outras fases (p,0,001). O PPT mostrou diferença significativa entre as fases menstruais (p=0,022), sem diferença nas comparações múltiplas. Os valores da EAV não apresentaram diferença entre as fases menstruais (p=376). CONCLUSÃO: Indivíduos saudáveis na fase luteal têm MPT e PPTl maior na região orofacial. Os relatos de dor em pacientes com DTM não mostraram diferença ao longo do ciclo menstrual, indicando que pequenas alterações nos limiares experimentais podem ser clinicamente relevantes. A presença de dor crônica parece estar mais relacionada com características psicossociais do que com flutuações hormonais.

Influence of genetic polymorphisms on mechanical pain sensitivity and endogenous pain modulation of trigeminal and spinal areas.

BACKGROUND: Previous evidence indicates significant association between genetic polymorphisms and phenotypes related to pain sensitivity in patients with temporomandibular disorders (TMD). Despite the important advances in cataloguing diverse factors such as sleep disorders, anxiety and depression, the interrelated mechanisms of painful TMD aetiopathogenesis still need investigation. OBJECTIVES: This case-control study aimed to evaluate the influence of genetic polymorphisms (rs6296, rs6295, rs1799971, rs4680, rs4633, rs4818) and psychosocial factors on the mechanical pain sensitivity and endogenous pain modulation in women with painful TMD and asymptomatic controls. METHODS: We evaluated six independent variables: anxiety levels, depression, stress, sleep quality, pain catastrophising and genetic polymorphisms, and four dependent variables: mechanical pain threshold (MPT), pressure pain threshold (PPT), wind-up ratio (WUR) and conditioned pain modulation (CPM) collected at masseter (trigeminal) and hand (spinal) areas in a sample of 95 painful TMD patients and 85 controls. A regression model was used to test the possible effect of the independent variables on dependent variables. RESULTS: The regression model was significant for MPT (F11,168  = 9.772; R2  = .390). Painful TMD diagnoses and sleep quality were associated with trigeminal MPT (B coefficient = -.499; and B coefficient = -.211, respectively). WUR was associated with rs6295 and rs6746030, respectively, for the spinal and the trigeminal area. CONCLUSION: Genetic polymorphisms had a slight contribution to endogenous pain modulation as indicated by the significant association with WUR but did not contribute to mechanical pain sensitivity. On the other hand, the presence of painful TMD and the sleep quality contributed significantly to mechanical pain sensitivity.

Divergence between confidence and knowledge of endodontists regarding non-odontogenic pain

Abstract This study aimed to assess the self-reported levels of confidence and knowledge related to non-odontogenic pain among a group of Brazilian endodontists. Methodology A total of one hundred and forty-six endodontists affiliated with the Brazilian Society of Endodontics participated in the survey. The questionnaire, distributed via email or WhatsApp, contained inquiries designed to gauge self-perceived confidence and knowledge concerning non-odontogenic pain. The practitioners were categorized into four groups based on their self-reported familiarity with various orofacial pain types, classified as either sufficient or insufficient, and on their engagement in ongoing educational programs related to orofacial pain. Data were analyzed by Chi-Square Test and Fischer's exact test (p<0.05). Results Overall, self-reported confidence about non-odontogenic pain was high, especially for endodontists who considered their knowledge about orofacial pain sufficient, regardless of whether they had (71.1% - 97.8%) or not (35.7% - 96.4%) been continuously involved in education courses on orofacial pain. In general, self-reported knowledge about non-odontogenic pain was insufficient (0% - 42%), except in the question about how they would act in cases of pain that persists beyond the normal healing time after an endodontic procedure (70.6% - 81.9%). In general, endodontists are confident in their diagnosis and treatment of non-odontogenic pain. Nonetheless, this confidence did not correlate with a commensurate knowledge depth of. Thus, specialization courses in endodontics should highly consider training and qualifying these professionals in the diagnosis of non-odontogenic pain.

Influence of awake bruxism behaviors on fatigue of the masticatory muscles in healthy young adults

Abstract The present cross-sectional study aimed to analyze the relationship between awake bruxism and fatigue of masticatory muscles in healthy young adults. For this purpose, 121 graduate students participated in this study. Frequency of awake bruxism was collected for 7 consecutive days by ecological momentary assessment (EMA) using an online survey (mentimeter). Muscle fatigue was tested one day after EMA assessment, which consisted of voluntarily and continuously clenching at 30% (kgf/cm2) of maximum bite force (MBF) until exhaustion. The percentage of change in MBF after the clenching task, as compared to the MBF before the clenching task was measured. The average frequency of awake bruxism was 45.5% during 7 days. Sustained clenching resulted in a significant reduction in MBF values in the total sample (p < 0.05). Nevertheless, no significant correlation was found between frequency of awake bruxism behaviors and percent of change in MBF and endurance time during the fatigue test. Therefore, it can be concluded that young healthy adults present a relatively high frequency of awake bruxism behaviors that do not seem to impact the degree of masticatory muscle fatigue.

Pain's Adverse Impact on Training-Induced Performance and Neuroplasticity: A Systematic Review.

Motor training is a widely used therapy in many pain conditions. The brain's capacity to undergo functional and structural changes i.e., neuroplasticity is fundamental to training-induced motor improvement and can be assessed by transcranial magnetic stimulation (TMS). The aim was to investigate the impact of pain on training-induced motor performance and neuroplasticity assessed by TMS. The review was carried out in accordance with the PRISMA-guidelines and a Prospero protocol (CRD42020168487). An electronic search in PubMed, Web of Science and Cochrane until December 13, 2019, identified studies focused on training-induced neuroplasticity in the presence of experimentally-induced pain, 'acute pain' or in a chronic pain condition, 'chronic pain'. Included studies were assessed by two authors for methodological quality using the TMS Quality checklist, and for risk of bias using the Newcastle-Ottawa Scale. The literature search identified 231 studies. After removal of 71 duplicates, 160 abstracts were screened, and 24 articles were reviewed in full text. Of these, 17 studies on acute pain (n = 7) or chronic pain (n = 10), including a total of 258 patients with different pain conditions and 248 healthy participants met the inclusion criteria. The most common types of motor training were different finger tasks (n = 6). Motor training was associated with motor cortex functional neuroplasticity and six of seven acute pain studies and five of ten chronic pain studies showed that, compared to controls, pain can impede such trainings-induced neuroplasticity. These findings may have implications for motor learning and performance and with putative impact on rehabilitative procedures such as physiotherapy.

Effects of acute mental stress on conditioned pain modulation in temporomandibular disorders patients and healthy individuals.

BACKGROUND: Stress is a contributing factor to painful temporomandibular disorders (TMD). Nevertheless, the underpinnings of this relationship are not fully understood. OBJECTIVE: To investigate the effects of acute mental stress on conditioned pain modulation (CPM) in TMD patients compared with healthy individuals. METHODOLOGY: Twenty women with chronic myofascial TMD diagnosed according to the RDC/TMD and 20 age-matched healthy women had the CPM assessed before and after a stressful task using the Paced Auditory Serial Addition Task (PASAT) in a single session. Subjective stress response was assessed with the aid of visual analog scale (VAS). Pressure pain threshold (PPT) on masseter muscle was the test stimulus (TS) and immersion of the participant's hand on hot water was the conditioning stimulus (CS) - CPM-sequential paradigm. RESULTS: Healthy individuals reported PASAT are more stressful when compared with TMD patients and the stress task did not affect the CPM in neither group. Nonetheless, a negative correlation was observed between change in CPM and change in TS from baseline to post-stress session, which indicates that the greater the increase in PPT after the stress task, the greater was the decrease in CPM magnitude. The correlation was strong for healthy controls (r=- 0.72, p<0.001) and moderate for TMD patients (r=- 0.44, p=0.047). CONCLUSIONS: The correlation between the change in CPM and the TS change following the stress task may possibly indicate an overlapping pathway between stress-induced analgesia/hyperalgesia and descending pain inhibition.

Multifocal Analysis of Acute Pain After Third Molar Removal.

Background: To analyze the pain modulation capacity profile in a Brazilian population, the relationship between opioid receptor (OPRM1) and Catechol-O-methyltransferase (COMT) 1polymorphisms and pain modulation capacity was determined through preoperative pain modulation tests and acute postoperative pain control evaluation, swelling, and trismus in 200 volunteers undergoing lower third molar removal. Methods: Psychologic and clinical parameters were measured. Patient DNA was sequenced for single nucleotide polymorphisms in OPRM1 and COMT, and the salivary concentration of interleukin (IL)-2 (IL)-6, interferon (IFN)-γ and tumor necrosis factor (TNF)-α was evaluated. Primary outcomes were the influence of all predictors on the fluctuation of pain intensity using a visual analogue scale (VAS), and swelling and trismus on the 2nd and 7th postoperative days. Preoperative pain modulation capacity (CPM), pain catastrophizing scale (PCS), body mass index (BMI), and surgery duration and difficulty were evaluated. Results: Salivary concentration of IFN-γ and IL-2 as well as the duration of surgery influenced the fluctuation of postoperative pain in the VAS, and in the sum of the differences in pain intensity test at 8, 48, and 96 h. BMI influenced swelling, while both BMI and COMT haplotype influenced trismus on the 2nd postoperative day. Conclusion: Polymorphisms in COMT, salivary concentrations of IL-2 and IFN-γ, BMI, and duration of surgery were predictors for pain fluctuation, swelling, and trismus on the 2nd day after lower third molar extraction. This therapy was effective in controlling inflammatory symptomatology after lower third molar extraction and ibuprofen was well tolerated by patients. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03169127.

Pain complications of oral implants: Is that an issue?

The use of oral implants as a form of replacing missing teeth in partial or total edentulous patients is considered the gold standard in oral rehabilitation. Although considered a history of success in contemporary dentistry, surgical complications may occur, as excessive bleeding, damage to the adjacent teeth and mandibular fractures. Persistent pain and abnormal somatosensory responses after the surgery ordinary healing time are also potential problems and may lead to the development of a condition named posttraumatic trigeminal neuropathic pain (PTNP). Though relatively rare, PTNP has a profound impact on patient's quality of life. Appropriated previous image techniques, effective anaesthetic procedures and caution during the surgical procedure and implant installation are recommended for the prevention of this condition. In case of the PTNP, different management modalities, including antidepressant and membrane stabilizer medications, as well as peripheral strategies, as the use of topical medication and the botulin toxin are presented and discussed.

Influence of self-reported physical activity and sleep quality on conditioned pain modulation in the orofacial region.

OBJECTIVES: To evaluate the influence of self-reported physical activity and sleep quality on conditioned pain modulation (CPM) in the orofacial region. MATERIALS AND METHODS: Ninety healthy participants aged 18-50 years old were evenly distributed according to the level of physical activity into low, moderate, and high level. The classification of physical activity was based on modified criteria of the International Physical Activity Questionnaire (IPAQ), considering intensity, duration, and frequency of physical activity. The Pittsburgh Sleep Quality Index (PSQI) assessed sleep quality and the individuals were then classified as good or poor sleepers. CPM was assessed using the pressure pain threshold (PPT) of the anterior temporalis as test stimulus and hand immersion in hot water as conditioning stimulus. ANOVA was applied to the data and Tukey's posttest was applied when the main effects or interactions were significant (p < 0.050). RESULTS: There was no significant main effect of neither physical activity nor sleep quality on pain modulation. However, individuals who reported high level of physical activity and good quality of sleep had a greater pain modulation (- 0.60 ± 0.34) when compared with those who reported moderate (- 0.10 ± 0.25) and low level of physical activity (- 0.10 ± 0.52) and good sleep quality (p < 0.028). CONCLUSIONS: Pain modulation seems to be more efficient in individuals who report a good sleep quality and a high level of physical activity. CLINICAL RELEVANCE: Conditioned pain modulation is highly variable in healthy people. Therefore, a multifactorial approach should be taken into consideration in the evaluation of the efficacy of endogenous analgesia.

A crossover clinical study to evaluate pain intensity from microneedle insertion in different parts of the oral cavity.

The objective of the present study was to evaluate discomfort and safety of microneedle (MN) insertion in several intraoral regions. A device was developed to standardize MN insertions. MNs were inserted in the following regions of the oral cavity: gingiva, palatine alveolar process, buccal mucosa, dorsum of the tongue and inner portion of the lower lip. Perforations from MNs post insertion were confirmed with topical gentian violet stain. Pain was evaluated in a randomized, double-blinded, crossover study in 30 volunteers. Each volunteer received a MN patch, a 30G hypodermic needle (positive control) and an identical MN patch with its needles laying flat in the plane of the patch (negative control). Adverse events were visually evaluated immediately after (0 h) and 24 h post MN application. The application device developed a consistent application force (10 N) and promoted perforation of all individual MNs on a patch. At all sites, insertion of the hypodermic needle promoted more pain when compared to the negative control (p < 0.001). Application of the MNs promoted less pain than the hypodermic needle (p < 0.05), but slightly more pain as compared to the negative control (p < 0.05) at all sites except the tongue, where the MN did not differ from the negative control (p > 0.05). Hypodermic needle caused bleeding at all insertion sites. In contrast, MNs did not cause bleeding at most sites except in some cases of insertion into the hard gingiva and the palatine alveolar process where tiny blood spots appeared immediately after MN application for few of the MNs on the patch. There were no cases of bleeding at 24 h post MN application. In conclusion, MNs can perforate different sites of the oral cavity in a safe and significantly less painful manner as compared to the 30G hypodermic needle. Thus, analogous to the skin, MN-based approaches could be an attractive approach for drug delivery in the oral cavity.

Effects of acute mental stress on conditioned pain modulation in temporomandibular disorders patients and healthy individuals

Abstract Stress is a contributing factor to painful temporomandibular disorders (TMD). Nevertheless, the underpinnings of this relationship are not fully understood. Objective To investigate the effects of acute mental stress on conditioned pain modulation (CPM) in TMD patients compared with healthy individuals. Methodology Twenty women with chronic myofascial TMD diagnosed according to the RDC/TMD and 20 age-matched healthy women had the CPM assessed before and after a stressful task using the Paced Auditory Serial Addition Task (PASAT) in a single session. Subjective stress response was assessed with the aid of visual analog scale (VAS). Pressure pain threshold (PPT) on masseter muscle was the test stimulus (TS) and immersion of the participant's hand on hot water was the conditioning stimulus (CS) - CPM-sequential paradigm. Results Healthy individuals reported PASAT are more stressful when compared with TMD patients and the stress task did not affect the CPM in neither group. Nonetheless, a negative correlation was observed between change in CPM and change in TS from baseline to post-stress session, which indicates that the greater the increase in PPT after the stress task, the greater was the decrease in CPM magnitude. The correlation was strong for healthy controls (r=- 0.72, p<0.001) and moderate for TMD patients (r=- 0.44, p=0.047). Conclusions The correlation between the change in CPM and the TS change following the stress task may possibly indicate an overlapping pathway between stress-induced analgesia/hyperalgesia and descending pain inhibition.

Effect of Genetic Polymorphisms on Pain Sensitivity in the Orofacial Region: A Systematic Review.

AIMS: To systematically review the literature to assess whether genetic polymorphisms affect orofacial pain sensitivity in healthy individuals and in patients with chronic orofacial pain disorders. METHODS: Electronic searches were conducted to identify observational studies and clinical trials investigating the association between genetic polymorphisms and orofacial pain sensitivity in healthy individuals and/or patients with chronic orofacial pain disorders. Searches were carried out in PubMed, Embase, and Scopus databases using Medical Subject Headings and free terms. RESULTS: Seven studies fulfilled the eligibility criteria: four analyzed healthy subjects, two included chronic orofacial pain patients, and one included samples of healthy subjects and patients with neuropathic pain. The results showed that genes associated with mechanical and thermal pain sensitivity were mostly related to opioid, catecholaminergic, inflammatory, and dopaminergic pathways. CONCLUSION: Genetic polymorphisms related to opioid, catecholaminergic, inflammatory, and dopaminergic pathways were associated with sensitivity to thermal and pressure stimuli in the orofacial region. Therefore, genetic factors should be taken into account for an accurate interpretation of orofacial pain sensitivity. These results will allow for a better understanding of the etiopathogenesis of chronic pain affecting the orofacial region, and consequently for finding new therapeutic targets.

The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment.

INTRODUCTION: This study aimed to evaluate whether the presence of awake bruxism was associated with temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment. METHODOLOGY: This observational study followed patients who had started receiving orthodontic treatment for six months. The following variables were measured three times (at baseline, one month, and six months): pressure pain threshold (PPT) in the right and left masseter, anterior temporalis, and temporomandibular joint (TMJ), and right forearm; pain vigilance and awareness questionnaire; and shortened form of the oral health impact profile (OHIP-14). Anxiety and depression symptoms were measured using the Beck anxiety inventory and the Beck depression inventory, respectively. The patients were divided into two main groups according to the presence (n=56) and absence (n=58) of possible awake bruxism. The multi-way analysis of variance (ANOVA) was applied on the date (p=0.050). RESULTS: TMJ and/or muscle pain were not observed in both groups. Time, sex, age group, and awake bruxism did not affect the PPT in the masticatory muscles and pain vigilance (p>0.050). However, the primary effect of awake bruxism was observed when anxiety (ANOVA: F=8.61, p=0.004) and depression (ANOVA: F=6.48, p=0.012) levels were higher and the OHRQoL was lower (ANOVA: F=8.61, p=0.004). CONCLUSION: The patients with self-reported awake bruxism undergoing an orthodontic treatment did not develop TMJ/masticatory muscle pain. The self-reported awake bruxism is associated with higher anxiety and depression levels and a poorer OHRQoL in patients during the orthodontic treatment.

Sleep architecture and factors associated with sleep bruxism diagnosis scored by polysomnography recordings: A case-control study.

OBJECTIVE: This study evaluated the association between the diagnosis of sleep bruxism (SB), scored by way of polysomnographic (PSG) recordings, clinical conditions and sleep architecture. DESIGN: A case-control study was conducted. All records from adults who had undergone polysomnography (PSG) recordings at a private medical outpatient clinic between January 2015 and December 2017 were reviewed. The sample included 58 bruxers (case group) and 58 non-bruxers (control group), identified based on the PSG recording and matched by sex and age. RESULTS: Obese individuals had significantly lower chance (OR 0.18; 95 % CI: 0.05-0.62; P = 0.005) of an SB diagnosis than individuals with normal BMI. Alcohol consumption significantly increased (OR 2.74; 95 % CI: 1.11-6.78; P = 0.029) and OSA decreased the chances (OR 0.55; 95 % CI: 0.23-1.30; P = 0.173) of an SB diagnosis. Bruxers had a significantly shorter wake time after sleep onset (WASO) (p = 0.002). As far as non-rapid eye movement (NREM) is concerned, the duration of stage N1 was statistically shorter (p = 0.034) and the duration of stage N3 was statistically longer (p = 0.001) in bruxers. Arousals (p = 0.013), arousals per hour (p = 0.009), respiratory disturbance index (RDI) values (p < 0.0005) and the apnoea-hypopnea index (AHI) (p = 0.002) were all lower in bruxers than in non-bruxers. CONCLUSION: The results of this study support a significant association between SB diagnosis, BMI and alcohol consumption. SB modified the sleep architecture as statistically significant differences were found between bruxers and non-bruxers for WASO, NREM stage N1 and N3, arousals, arousals per hour, RDI and AHI.

Topical anaesthesia degree is reduced in temporomandibular disorders patients: A novel approach to assess underlying mechanisms of the somatosensory alterations.

BACKGROUND: Changes in quantitative sensory testing (QST) parameters following topical anaesthesia could contribute to better elucidate underlying mechanisms of somatosensory alterations in temporomandibular disorder (TMD) pain patients. This placebo-controlled crossover investigation compared the somatosensory profile following topical anaesthesia between TMD patients (n = 20) and healthy participants (n = 20). METHODS: Cold detection threshold, warm detection threshold, cold pain threshold, heat pain threshold, mechanical detection threshold, mechanical pain threshold, wind-up ratio and pressure pain threshold were assessed on the skin overlying the masseter at three consecutive days (baseline and immediately after lidocaine 4%/placebo cream). Mixed ANOVA and a coding system that accounts for the diversity of types of peripheral axons associated with the somatosensory parameters were applied for data analysis. RESULTS: The lidocaine application caused no changes in the somatosensory sensitivity in the masseter region in TMD patients (P > .050), but sensitivity to cold, cold pain, touch and pinprick stimuli were reduced after topical anaesthesia in healthy participants (P < .050). Also, the degree of topical anaesthesia was greater in healthy participants (P = .008). The coding system suggested that TMD patients presented only Aδ-fibre block, whereas a combination of either Aß- and/or C-fibre block was observed in 35% of healthy participants in addition to Aδ-fibre block following lidocaine application. CONCLUSION: Quantitative sensory testing can be successfully applied to identify meaningful differences in the degree of hypoalgesia and hypoesthesia following short-time topical anaesthesia.

Feasibility and reliability of intraorally evoked "nociceptive-specific" blink reflexes.

OBJECTIVES: The "nociceptive-specific" blink reflex (nBR) evoked by extraoral stimulation has been used to assess trigeminal nociceptive processing in patients with trigeminal nerve damage regardless of the site of damage. This study aimed to test the feasibility of nBR elicited by intraoral stimulation, compare intraoral and extraoral nBR and assess the intrarater and interrater reliability of the intraoral nBR for the maxillary (V2) and mandibular (V3) branches of the trigeminal nerve. MATERIALS AND METHODS: In 17 healthy participants, nBR was elicited by stimulation of two extraoral and two intraoral sites by two operators and repeated intraorally by one operator. Main outcome variables were intraoral stimulus-evoked pain scores and nBR R2 responses at different stimulus intensities. Intraclass correlation coefficients (ICC) were used to assess reliability. RESULTS: Dependent on the stimulus intensity, intraoral stimulation evoked R2 responses in up to 12/17 (70.6%) participants for V2 and up to 8/17 (47.1%) participants for V3. Pain scores (p < 0.003) and R2 responses (p < 0.004) increased with increasing intensities for V2, but not V3. The R2 responses were significantly smaller with intraoral stimulation compared to extraoral stimulation (p < 0.014). Overall, ICCs were fair to excellent for V2 but poor for V3. CONCLUSION: Intraorally evoked nBR was feasible in a subset of healthy participants and was less responsive than nBR with extraoral stimulation. The V2 nBR showed better reliability than V3. CLINICAL RELEVANCE: The nBR can be used to assess nerve damage to the maxillary intraoral regions, though other measures may need to be considered for the mandibular intraoral regions.