Chronic jaw pain attenuates neural oscillations during motor-evoked pain.

Motor- and pain-related processes separately induce a reduction in alpha and beta power. When movement and pain occur simultaneously but are independent of each other, the effects on alpha and beta power are additive. It is not clear whether this additive effect is evident during motor-evoked pain in individuals with chronic pain. We combined highdensity electroencephalography (EEG) with a paradigm in which motor-evoked pain was induced during a jaw force task. Participants with chronic jaw pain and pain-free controls produced jaw force at 2% and 15% of their maximum voluntary contraction. The chronic jaw pain group showed exacerbated motor-evoked pain as force amplitude increased and showed increased motor variability and motor error irrespective of force amplitude. The chronic jaw pain group had an attenuated decrease in power in alpha and lower-beta frequencies in the occipital cortex during the anticipation and experience of motor-evoked pain. Rather than being additive, motor-evoked pain attenuated the modulation of alpha and beta power, and this was most evident in occipital cortex. Our findings provide the first evidence of changes in neural oscillations in the cortex during motor-evoked jaw pain.

Influence of double flask investing and microwave heating on the superficial porosity, surface roughness, and knoop hardness of acrylic resin.

PURPOSE: Simultaneous polymerization of maxillary and mandibular complete dentures with teeth in occlusion through investing in a double special flask has been described as a more rapid and efficient method to polymerize prostheses than the conventional method; however, no study has been done to verify important properties of resin, including superficial porosity, surface roughness, and hardness, when processed by this technique. The purpose of this study was to verify if the simultaneous polymerization associated with microwave heating may alter the superficial porosity, surface roughness, and Knoop hardness of acrylic resin. MATERIALS AND METHODS: Resin specimens processed in single and double dental flasks were compared using microwave energy and warm water methods. Four groups were tested according to the investing flask and the method of resin cure: Group I control specimens (n = 15) were invested in single metal flasks and cured by warm water at 74 degrees C for 9 hours. Group II (n = 15) specimens were invested in single polyvinyl chloride flasks and cured by microwave energy at 90 W for 20 minutes plus 450 W for 5 minutes. Group III (n = 30) and Group IV (n = 30) specimens were processed by simultaneous polymerization in double flasks and cured by the same warm water and microwave energy protocols, respectively. RESULTS: No significant differences were found in mean superficial porosity (8.06 +/- 2.28 pore/cm(2)), surface roughness (0.14 +/- 0.03 mum), or Knoop hardness (19.66 +/- 2.25 kgf/mm(2)) between the control group (GI), and the other three experimental groups (p > 0.05). CONCLUSION: Processing acrylic resin in a double flask heated by either warm water or microwave energy does not alter the resin's superficial porosity, surface roughness, or Knoop hardness; however, other properties of resin should be analyzed using this denture processing technique.

Altered neural oscillations within and between sensorimotor cortex and parietal cortex in chronic jaw pain.

Pain perception is associated with priming of the motor system and the orienting of attention in healthy adults. These processes correspond with decreases in alpha and beta power in the sensorimotor and parietal cortices. The goal of the present study was to determine whether these findings extend to individuals with chronic pain. Individuals with chronic jaw pain and pain-free controls anticipated and experienced a low pain or a moderate pain-eliciting heat stimulus. Although stimuli were calibrated for each subject, stimulus temperature was not different between groups. High-density EEG data were collected during the anticipation and heat stimulation periods and were analyzed using independent component analyses, EEG source localization, and measure projection analyses. Direct directed transfer function was also estimated to identify frequency specific effective connectivity between regions. Between group differences were most evident during the heat stimulation period. We report three novel findings. First, the chronic jaw pain group had a relative increase in alpha and beta power and a relative decrease in theta and gamma power in sensorimotor cortex. Second, the chronic jaw pain group had a relative increase in power in the alpha and beta bands in parietal cortex. Third, the chronic jaw pain group had less connectivity strength in the beta and gamma bands between sensorimotor cortex and parietal cortex. Our findings show that the effect of chronic pain attenuates rather than magnifies neural responses to heat stimuli. We interpret these findings in the context of system-level changes in intrinsic sensorimotor and attentional circuits in chronic pain.

Functional brain activity during motor control and pain processing in chronic jaw pain.

Changes in brain function in chronic pain have been studied using paradigms that deliver acute pain-eliciting stimuli or assess the brain at rest. Although motor disability accompanies many chronic pain conditions, few studies have directly assessed brain activity during motor function in individuals with chronic pain. Using chronic jaw pain as a model, we assessed brain activity during a precisely controlled grip force task and during a precisely controlled pain-eliciting stimulus on the forearm. We used multivariate analyses to identify regions across the brain whose activity together best separated the groups. We report 2 novel findings. First, although the parameters of grip force production were similar between the groups, the functional activity in regions including the prefrontal cortex, insula, and thalamus best separated the groups. Second, although stimulus intensity and pain perception were similar between the groups, functional activity in brain regions including the dorsal lateral prefrontal cortex, rostral ventral premotor cortex, and inferior parietal lobule best separated the groups. Our observations suggest that chronic jaw pain is associated with changes in how the brain processes motor and pain-related information even when the effector producing the force or experiencing the pain-eliciting stimulus is distant from the jaw. We also demonstrate that motor tasks and multivariate analyses offer alternative approaches for studying brain function in chronic jaw pain.

Motor-Evoked Pain Increases Force Variability in Chronic Jaw Pain.

Musculoskeletal pain changes how people move. Although experimental pain is associated with increases in the variability of motor output, it is not clear whether motor-evoked pain in clinical conditions is also associated with increases in variability. In the current study, we measured jaw force production during a visually guided force paradigm in which individuals with chronic jaw pain and control subjects produced force at 2% of their maximum voluntary contraction (low target force level) and at 15% of their maximum voluntary contraction (high target force level). State measures of pain were collected before and after each trial. Trait measures of pain intensity and pain interference, self-report measures of jaw function, and measures of depression, anxiety, and fatigue were also collected. We showed that the chronic jaw pain group exhibited greater force variability compared with controls irrespective of the force level, whereas the accuracy of force production did not differ between groups. Furthermore, predictors of force variability shifted from trait measures of pain intensity and pain interference at the low force level to state measures of pain intensity at the high force level. Our observations show that motor-evoked jaw pain is associated with increases in force variability that are predicted by a combination of trait measures and state measures of pain intensity and pain interference. PERSPECTIVE: Chronic jaw pain is characterized by increases in variability during force production, which can be predicted by pain intensity and pain interference. This report could help clinicians better understand the long-term consequences of chronic jaw pain on the motor system.

Clinical orofacial characteristics associated with risk of first-onset TMD: the OPPERA prospective cohort study.

UNLABELLED: Case-control studies have documented clinical manifestations of chronic temporomandibular disorder (TMD), whereas clinical predictors of TMD development are largely unknown. We evaluated 41 clinical orofacial characteristics thought to predict first-onset TMD in a prospective cohort study of U.S. adults aged 18 to 44 years. During the median 2.8-year follow-up period, 2,737 people completed quarterly screening questionnaires. Those reporting symptoms were examined and 260 people were identified with first-onset TMD. Univariate and multivariable Cox regression models quantified associations between baseline clinical orofacial measures and TMD incidence. Significant predictors from baseline self-report instruments included oral parafunctions, prior facial pain and its life-impact, temporomandibular joint noises and jaw locking, and nonspecific orofacial symptoms. Significant predictors from the baseline clinical examination were pain on jaw opening and pain from palpation of masticatory, neck, and body muscles. Examiner assessments of temporomandibular joint noise and tooth wear facets did not predict incidence. In multivariable analysis, nonspecific orofacial symptoms, pain from jaw opening, and oral parafunctions predicted TMD incidence. The results indicate that only a few orofacial examination findings influenced TMD incidence, and only to a modest degree. More pronounced influences were found for self-reported symptoms, particularly those that appeared to reflect alterations to systems beyond the masticatory tissues. PERSPECTIVE: OPPERA's prospective cohort study identifies predictors of first-onset TMD comprising self-reported orofacial symptoms and examination findings. The results suggest a complex pattern of TMD etiology that is influenced by disorders locally, in masticatory tissues, and systemically, in pain-regulatory systems.

Salivary cortisol level and uncooperative behavior in pediatric dental practice

Aim: To investigate the relation between uncooperative behavior and salivary cortisol level in childrenwho underwent preventive dental care. Methods: The sample was composed by 10 children of bothsexes aged 40 to 52 months, presenting uncooperative behavior during dental preventive treatments.The saliva collection was performed using a cotton wheel and an Eppendorf tube (Sarstedt Salivete®)in 3 different moments: a) at home, on a day without dental treatment and at the same time on theday of the sessions treatment; b) 30 min after the end of the session, when there was manifestationof uncooperative behavior; c) 30 min after the end of the session, when there was a cooperativebehavior of the child. A sample of saliva was centrifuged for 5 minutes at 2400 rpm, 1 of mL of salivawas pipetted in an Eppendorf tube and stored in a freezer at -20 ° C. For the determination of thelevels of salivary cortisol was used an Active® kit for cortisol enzyme immunoassay (EIA) DSL-10-67100, composed of specific rabbit antibody anti-cortisol. Data were analyzed statistically for theuncooperative behavior issued in the beginning and at the end of sessions, using the paired t test(p<0.05) and for cortisol levels in saliva samples at home, after the beginning and at the end ofsessions, using repeated-measures ANOVA and Tukey’s test (p<0.05). Results: During expression ofuncooperative behavior in preventive dental care sessions the salivary cortisol level was significantlyhigher (0.65 ± 0.25 µg/dL) compared with expression of collaborative behavior (0.24 ± 0.10 µg/dL).Conclusions: It is possible to conclude that, even under preventive intervention, the stress must becontrolled in order to reduce dental anxiety and fear.

Clinical findings and pain symptoms as potential risk factors for chronic TMD: descriptive data and empirically identified domains from the OPPERA case-control study.

Clinical characteristics might be associated with temporomandibular disorders (TMD) because they are antecedent risk factors that increase the likelihood of a healthy person developing the condition or because they represent signs or symptoms of either subclinical or overt TMD. In this baseline case-control study of the multisite Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) project, 1,633 controls and 185 cases with chronic, painful TMD completed questionnaires and received clinical examinations. Odds ratios measuring association between each clinical factor and TMD were computed, with adjustment for study-site as well as age, sex, and race/ethnicity. Compared to controls, TMD cases reported more trauma, greater parafunction, more headaches and other pain disorders, more functional limitation in using the jaw, more nonpain symptoms in the facial area, more temporomandibular joint noises and jaw locking, more neural or sensory medical conditions, and worse overall medical status. They also exhibited on examination reduced jaw mobility, more joint noises, and a greater number of painful masticatory, cervical, and body muscles upon palpation. The results indicated that TMD cases differ substantially from controls across almost all variables assessed. Future analyses of follow-up data will determine whether these clinical characteristics predict increased risk for developing first-onset pain-related TMD PERSPECTIVE: Clinical findings from OPPERA's baseline case-control study indicate significant differences between chronic TMD cases and controls with respect to trauma history, parafunction, other pain disorders, health status, and clinical examination data. Future analyses will examine their contribution to TMD onset.

Fatores associados aos sentimentos decorrentes da perda dentária total e às expectativas de reposição protética em adultos e idosos / Factors associated with feelings arising from total tooth loss and expectations of denture replacement in adults and elderly

Resumo Introdução A perda dentária é considerada um evento grave na vida dos pacientes e pode levá-los à reclusão social. A reabilitação por meio de próteses pode contribuir para a melhora da autoimagem de edêntulos totais. Objetivo Este estudo teve como objetivo conhecer os fatores associados aos sentimentos decorrentes da perda de dentes e às expectativas quanto à nova prótese. Métodos Estudo transversal analítico com 119 pacientes edêntulos totais (faixa etária entre 29 e 87 anos) em tratamento para confecção de prótese em uma clínica-escola. Resultados Os pacientes que relataram ter perdido seus dentes devido ao medo de submeter-se ao tratamento ou a dificuldades de acesso foram os que mais sofreram com a perda dentária (OR=2,57). Os pacientes mais jovens (OR=3,33) e do sexo feminino (OR=3,89) foram aqueles que demonstraram mais expectativas em relação à prótese que estava sendo confeccionada. Conclusão As mulheres e as pessoas mais jovens são aquelas que manifestaram mais raiva ou tristeza pela perda dentária e que possuíam expectativas estéticas e de socialização em relação à nova prótese.

Abstract Introduction The tooth loss is considered a serious event on the life of patients and it may take them to social withdrawal. The rehabilitation through prosthetics can improve self-image of total edentulous. Objective This study aimed to assess factors associated with feelings related to tooth loss and the expectations regarding the new prosthesis. Methods A cross-sectional study with 119 total edentulous patients (age range: 29-87 years) undergoing prostheses treatment in a University Clinic. Results The patients who reported having lost their teeth due to fear of undergoing treatment or access difficulties were the ones who suffered most from tooth loss (OR = 2.57). Younger patients (OR = 3.33) and female (OR = 3.89) were those that showed more expectations for the prosthesis that was being made. Conclusion Women and young people are those who express more anger or sadness due to tooth loss and have aesthetic and socialization expectations for the new prosthesis.

Influence of chemical and mechanical polishing on water sorption of acrylic resin polymerized by water bath and microwave irradiation

Previous studies have investigated the possible influences to different types of polymerization and polishing procedures in some properties of acrylic resins. Water sorption is an important property, which may be induced by these factors. The aim of this work was to evaluate water sorption in acrylic resin processed in microwave energy or water bath, after chemical and mechanical polishing. Forty heatpolymerized acrylic resin (Vipi-Cril, Dental VIPI Ltd, Pirassununga, São Paulo, Brazil) specimens were made according to ADA Specification No.12 for Denture Base Polymers and divided into 4 groups: Groups I and II were processed in microwave energy (500 W for 3 minutes); Groups III and IV, in water bath (73ºC ± 1ºC for 9 hours). Groups I and III were polished chemically; Groups II and IV were polished mecahnically. The specimens were submitted to water sorption test. The water sorption values (mg/cm2) were calculated and submitted to ANOVA and Tukeyïs test (5% significance level). The obtained results were: Group I: 0.000953, Group II: 0.001069, Group III: 0.000958 and Group IV: 0.001491. No statistical difference were found among the groups (p>.05). Polymerization by microwave energy or water bath associated with chemical or mechanical polishing did not influence the water sorption of the heat polymerized acrylic resin evaluated.