Effect of artificial eccentric occlusal interferences on masticatory performance: A randomised double-blind clinical trial.

BACKGROUND: Occlusal interferences lead to changes in mandibular kinematics to compensate and improve function. However, the effects of different types of eccentric disturbance on the comminution capacity are not known. OBJECTIVE: To determine the immediate effect of eccentric occlusal interferences on masticatory performance. METHODS: This crossover clinical trial included 12 healthy dentate subjects aged 25.2 ± 3.3 years who were randomly submitted to seven types of occlusal interference: unilateral and bilateral laterotrusive and mediotrusive, protrusive, dummy and control (no interference). The interference forms were planned in a semi-adjustable articulator, fabricated with composite resin and adhered to the mandibular first molars such that subjects' maximum intercuspation was maintained. Masticatory performance and the chewing rate during 20 cycles were evaluated during subjects' comminution of silicone test food under one interference condition per test day; the multiple sieve method was applied to the comminuted particles. The interference was removed upon test completion, and a 1-week washout period was applied between tests. RESULTS: Comminuted median particle sizes were larger under unilateral (4.94 ± 0.41 mm) and bilateral (4.81 ± 0.49 mm) laterotrusive, bilateral mediotrusive (4.65 ± 0.50 mm) and protrusive (4.83 ± 0.54 mm) interferences (p < .05) than under the control (4.01 ± 0.52 mm) and dummy (4.18 ± 0.58 mm) conditions (p < .05). Only unilateral and bilateral laterotrusive interferences narrowed the comminuted particle size dispersion (p < .05). The chewing rate did not differ among conditions (p = .1944). CONCLUSION: Artificial eccentric interferences had an immediate adverse effect on masticatory performance by resulting in larger comminuted particles. CLINICAL TRIAL REGISTRATION: Brazilian Registry of Clinical Trials (RBR-8g5zfg8).

Benefits of the combination of digital and analogic tools as a strategy to control possible awake bruxism: A randomised clinical trial.

BACKGROUND: Awake Bruxism (AB) management includes cognitive and behavioural changes. Digital and analogic tools can be used to remind the individual to control/avoid AB behaviours. However, no study addressed both tools together. OBJECTIVE: To compare the efficacy of the combination of digital (smartphone application) and analogic (adhesive reminders) tools versus digital tool alone for AB management. METHODS: Seventy-two individuals diagnosed with probable AB were divided into 3 groups: Group 1 (n = 24), used both digital and analogic tools during 30 days; Group 2 (n = 24), used only a digital tool during 30 days and Group 3 (n = 24), used only a digital tool for the first 15 days and then added the analogic tool for 15 days. The AB frequency was measured in real-time with a smartphone app, which sent alerts asking the individuals if they were doing any AB behaviours (bracing, teeth contact, clenching or grinding). Groups were compared using one-way ANOVA and before-after adding an analogic tool (group 3) by paired t-test, considering α = 0.05. RESULTS: All groups showed a decrease in AB behaviours at the end of the evaluation period. Group 1 (digital and analogic tools) showed the lowest average of AB behaviours among all groups; however, statistically significant differences were found only for the comparison between groups 1 and 2. In group 3, a significantly greater reduction in AB behaviours was found after combining both approaches. CONCLUSION: The combination of digital and analogic tools showed the greatest reduction of AB frequency and can be recommended for AB control.

The role of tryptophan and its derivatives in musculoskeletal pains: A systematic review and meta-analysis.

BACKGROUND: Studies present ambiguous findings regarding the role of tryptophan and its metabolites, kynurenine and serotonin in chronic musculoskeletal pain. This systematic review aimed to investigate the expression of tryptophan and its metabolites, serotonin and kynurenine in patients with local and generalized chronic musculoskeletal pain in comparison with pain-free controls. METHODS: An electronic search was conducted in the databases MEDLINE, CINAHL, EMBASE, the Cochrane Central Registry of Controlled Trials (CENTRAL) and Web of Science for clinical and observational trials from the beginning of each database to 21 April 2023. Out of 6734 articles, a total of 17 studies were included; 12 studies were used in the meta-analysis of serotonin, 3 regarding tryptophan and 2 studies for a narrative synthesis regarding kynurenine. Risk of bias was assessed using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute, while the certainty of evidence was by GRADE. RESULTS: All included studies showed a low risk of bias. The meta-analysis showed lower blood levels of tryptophan (p < .001; very low quality of evidence) and higher blood levels of serotonin (p < .001; very low-quality evidence) in patients with generalized musculoskeletal pain, when compared to pain-free individuals. In local chronic musculoskeletal pain, there were higher blood levels of serotonin (p=.251; very low quality of evidence) compared to pain-free individuals. Regarding kynurenine, the studies reported both higher and lower blood levels in generalized chronic musculoskeletal pain compared to pain-free individuals. CONCLUSIONS: The blood levels of tryptophan and its metabolites serotonin and kynurenine seem to influence chronic musculoskeletal pain.

Comparison of the Effectiveness of Different Methods for Pain Reduction During Injection Procedures in the Frontalis Muscle.

BACKGROUND: Forehead aesthetic injections are a well-known source of discomfort, and many analgesic non-invasive techniques have been proposed to ameliorate pain. However, no study has compared all these techniques for aesthetic purposes. Therefore, this study aimed to compare the effectiveness of topical cream anesthesia, vibratory stimulus, cryotherapy, pressure, and even no intervention, on pain during and immediately after injection, when considering aesthetic injections in the forehead. METHODS: Seventy patients were selected and had their foreheads divided into 5 parts, which received four different analgesic techniques, and one control zone was added. A numeric rating scale was used to assess pain, two direct questions were asked to evaluate patients' preference and discomfort with the techniques, and the adverse events were quantified. The injections were performed in the same sequence, with three minutes of rest between them and in a single session. Comparisons among analgesic methods for pain relief were performed by the one-way analysis of variance (ANOVA), considering a significance level of 5%. RESULTS: No significant differences were found among the analgesic methods, and between the methods and the control zone, both during and immediately after the injections (p > 0.05). The preferred method for pain relief was the use of topical anesthetic cream (47%), while the most uncomfortable technique was manual distraction (pressure) (36%). Only one patient reported an adverse event. CONCLUSIONS: No analgesic method to diminish pain was superior to the others or was better than no method. Nevertheless, the topical anesthetic cream was the preferred technique, causing less discomfort. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Histomorphometric Changes of the Masseter Muscle of Rats After a Single Injection of Botulinum Toxin Type A.

BACKGROUND: It has been reported that botulinum toxin type A (BoNT-A) produces structural changes in masticatory muscles. However, not all histomorphometric parameters affected by BoNT-A parameters have been assessed. This study investigated the histomorphometric changes in the masseter muscle of rats after a single injection of BoNT-A. METHODS: Forty-four adult animals were randomly divided into control group (n = 22) and BoNT-A group (n = 22). Controls received a single dose of 0.14 mL/kg of saline in masseter muscles, and the BoNT-A group received a 7 U/Kg of BoNT-A. The groups received the same volume of injected substances. Animals were sacrificed on 7th (n = 5), 14th (n = 5), 21st (n = 5), 28th (n = 4) and 90th (n = 3) days post-treatment. Histological masseter tissue slides were obtained from hematoxylin-eosin treatment and analyzed in optical microscopy regarding muscle cross-sectional area, amount of connective tissue and quantity and diameter of myocytes. For statistical analysis, generalized linear models were used to compare the data (ANOVA). In all test, the significance level of 5% was set. RESULTS: BoNT-A values of cross-sectional area of the masseter muscle were significantly lower than controls (p < 0.01) throughout the study. Regarding myocytes quantity, BoNT-A subgroups presented higher values than controls (p < 0.0001) since the 14th day until the end of the study; however, the diameter of myocytes was smaller in all BoNT-A subgroups (p < 0.0001) in all assessment points. The amount of connective tissue was higher in BoNT-A subgroups (p < 0.0001) throughout the study. CONCLUSION: A single injection of BoNT-A altered the structure of masseter muscle of rats, regarding its histomorphometric parameters. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Temporalis Muscle Changes Following Botulinum Toxin A Injections in Masseter Hypertrophy Patients: A Randomized Triple-Blinded Trial.

BACKGROUND: This study aimed to elucidate the effects of botulinum toxin A (BoNT-A) treatment for patients diagnosed with masseter hypertrophy on the temporalis muscle, with a particular focus on assessing alterations in muscle thickness, electromyographic (EMG) activity, and the development of muscle pain. METHODS: The present randomized triple-blinded clinical trial enrolled 26 female participants aged between 25 and 50 years complaining about masseter hypertrophy. Participants received 75U of BoNT-A (abobotulinumtoxinA) in both masseter muscles and after three months were randomized to receive a second treatment session of saline solution (S-BoNT-A) or BoNT-A (M-BoNT-A). Longitudinal assessments included temporalis muscle thickness through ultrasound, EMG activity, subjective pain, and masseter prominence severity after one, three, and six months of the first injection session. Muscle thickness, EMG, and subjective pain were analysed using two-way ANOVA with repeated measures and post hoc Sidak test, and for masseter prominence severity, Friedman and Mann-Whitney tests were used. RESULTS: Regarding inter-group comparisons, a higher muscle thickness (p < 0.02) and a higher EMG activity (p < 0.01) were found in the M-BoNT-A group at the 6-month follow-up. For subjective pain assessments, inter-group comparisons showed a higher prevalence of painful regions in M-BoNT-A group at the 6-month follow-up (p < 0.02). No significant differences were found in masseter prominence severity at the 6 months assessment between groups. CONCLUSION: BoNT-A treatment for masseter hypertrophy lead to structural and functional changes in the temporalis muscle, presenting higher changes after multiple injections of this treatment. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Do sociodemographic factors influence the levels of health and oral literacy? A cross-sectional study.

BACKGROUND: Oral health literacy has gained importance in dental literature, and its relationship with oral health status and association with health status (HL) has been reported. Then, an association between the levels of HL and OHL could be expected. This study aimed to assess the levels of HL and OHL according to sociodemographic factors and to explore a possible association between HL and OHL. METHODS: The European Health Literacy Survey and Oral Health Literacy Adults Questionnaire were applied to a convenience sample from Portuguese individuals. Also, sociodemographic factors such as sex, age, schooling level of the participants and their parents, and if the participants were professionals or students of the health field were assessed. To analyze the data, the Kruskal-Wallis and Mann-Whitney U tests were used to compared sociodemographic variables and the levels of literacy in general and oral health. The Spearman correlation test assessed the correlation between the levels of HL and OHL. RESULTS: HL results showed that 45.1% of the volunteers were considered in a "problematic level" and 10.3% in "excellent level". However, 75% presented an adequate level of OHL. Regarding the levels of HL in each sociodemographic variable, significant higher levels of "excellent level" were found in health professionals and students when compared with participants not related to health area (p < 0.001). Comparisons between the levels of OHL in each sociodemographic variable showed, significant differences regarding sex (p < 0.05), age (p < 0.001), levels of schooling of the participants and their parents (p < 0.009 and p < 0.001) and relationship with health field. (p < 0.001). A significant positive - weak correlation was found between HL and OHL (p < 0.001). CONCLUSIONS: HL and OHL levels are associated and could be influenced by sociodemographic factors.

Prevalence of awake bruxism in the adult population: a systematic review and meta-analysis.

OBJECTIVES: To evaluate the prevalence of awake bruxism (AB) in the adult population. MATERIALS AND METHODS: Six main electronic databases and three sources of grey literature were searched to identify cross-sectional studies in which AB was assessed. The studies were independently selected by two reviewers in two phases, based on their eligibility criteria. The first one consisted of reading titles and abstracts, and the second one involved reading the full articles. The study quality assessment was obtained by using the "Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data", and the "R Statistics" software was used to perform meta-analyses. RESULTS: Seventeen out of 3086 identified studies were included. None of the studies scored high in methodological quality across all 9 items of the JBI checklist. However, "the use of valid methods to identify pathology" and "appropriate statistical analysis" were considered to have high methodological quality in all the studies. The overall pooled prevalence of the meta-analysis was 15.44% (99% confidence interval: 10.81 to 20.72%) and there was no difference for sex, sampling method and according to consensus-based classification. CONCLUSIONS: The prevalence of AB in adults was low. There was substantial methodological variability, which highlights the need for standardized guidelines. CLINICAL RELEVANCE: Prevalence data are useful for raising patients' and clinicians' awareness of the AB. Moreover, since AB can lead to possible pain and overload of the stomatognathic system, this knowledge can also guide dentists to achieve an early diagnosis of AB and to provide appropriate care management.

Who is the individual that will complain about temporomandibular joint clicking?

BACKGROUND: Understanding the profile of the individual complaining of TMJ clicking can help in the clinical approach of these patients. OBJECTIVE: To identify clinical variables associated with individuals who complain about and seek treatment for TMJ clicking. METHODS: Seventy-two individuals, composed the sample: Group 1 - patients with a complaint of TMJ clicking who sought treatment; (n = 36); Group 2 - individuals with TMJ clicking who have no complaints about it (n = 36). Three categories of data were evaluated: clinical (gender; age; side of TMJ clicking; TMJ pain; self-reported level of bother; previous TMJ clicking information); somatosensory (mechanical pain threshold [MPT], wind-up ratio [WUR], pressure pain threshold [PPT]); and, psychosocial (Pain Vigilance and Awareness Questionnaire [PVAQ]; Pain Catastrophising Scale [PCS]; Tampa Scale for Kinesiophobia for Temporomandibular Disorders [TSK/TMD]); The Perceived Stress Scale (PSS); The State-Trait Anxiety Inventory (STAI). RESULTS: Group 1 was composed mostly of female patients, with TMJ pain, without previous orientation about the condition, bothered by the clicking, with lower PPT and higher scores in the PVAQ, PCS, TKS/TMD, PSS and STAI scales than Group 2. The groups did not differ significantly for side of TMJ clicking, age, MPT and WUR. CONCLUSION: Individuals who have a TMJ clicking complaint and seek treatment are mostly female, have TMJ pain, have not received previous orientation about TMJ clicking, are bothered by the clicking, have a lower pain threshold and higher scores of hypervigilance, catastrophising, kinesiophobia, stress and anxiety than people with TMJ clicking who do not report it.

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.

The effectiveness of microwave disinfection in treating Candida-associated denture stomatitis: a systematic review and metaanalysis.

OBJECTIVE: To evaluate the effectiveness of microwave disinfection in treating Candida-associated denture stomatitis (CADS). MATERIALS AND METHODS: The PubMed/MEDLINE, Embase, and Scopus databases were searched for reports on randomized clinical trials (RCTs) published in English until May 2020 (PROSPERO CRD42020192062) that evaluated the treatment of CADS by using microwave disinfection. The main outcomes were the improvement of clinical signs and/or the decrease in the residual yeast present on the dentures and palatal mucosa. The mean differences, standard deviations, risk ratio, and 95% confidence interval were calculated by using the random-effects model. Heterogeneity was assessed by using Cochran's Q test and I2 values. The level of significance was set at α = 0.05. RESULTS: Five RCTs with 245 participants were included. The descriptive investigations demonstrated that microwave disinfection was as effective (p > 0.05) as 0.2% chlorhexidine, 0.02% sodium hypochlorite, and topical nystatin (100.000 IU/mL), and was superior to topical miconazole in treating CADS. The metaanalysis did not show a statistical difference between microwave disinfection and nystatin (100.000 IU/mL) treatment in terms of mycological counts, cure, and recurrence rates (p > 0.05). CONCLUSION: Microwave disinfection showed comparable results with those of conventional therapies for treating CADS. In addition, treatment with 650 W for 3 min once a week for 14 days had better cost-effect results, indicating both the prevention and treatment of CADS. CLINICAL RELEVANCE: Our findings provide evidence regarding the treatment of CADS using microwave disinfection, and also indicating the best cost-effective option for this treatment modality.

Somatosensory and psychosocial profile of patients with painful temporomandibular joint clicking.

BACKGROUND: Determining the somatosensory and psychosocial profile of patients with painful temporomandibular joint (TMJ) clicking can help to understand the pain mechanisms in cases of TMJ clicking. OBJECTIVE: To characterise the somatosensory and psychosocial profile of patients with painful TMJ clicking when compared to patients with painless TMJ clicking and healthy control group. METHODS: Somatosensory and psychosocial functions were assessed in 90 individuals: patients with painful TMJ clicking (n = 30); patients with painless TMJ clicking (n = 30); and healthy controls (n = 30). Somatosensory profile included: mechanical pain threshold (MPT); wind-up ratio (WUR); pressure pain threshold (PPT); and conditioned pain modulation (CPM). Psychosocial profile included some questionnaires: Pittsburgh Sleep Quality Index (PSQI); Pain Vigilance-Awareness Questionnaire (PVAQ); Pain Catastrophizing Scale (PCS); Tampa Scale for Kinesiophobia (TSK); Perceived Stress (PSS); and State-Trait Anxiety Inventory (STAI). All variables were compared among all groups. RESULTS: Higher values of MPT and WUR; lower PPT; less efficient CPM; and higher scores of PSQI, PVAQ, PCS, and TSK were found in patients with painful TMJ clicking when compared to the other two groups (P < .001). Patients with painless TMJ clicking showed lower PPT and higher scores of PVAQ and TKS than the healthy control group. PSS and STAI data had no differences. CONCLUSION: Patients with painful TMJ clicking had abnormalities in the somatosensory profile, with a significant somatosensory gain of function (more sensitive) to mechanical pain tests and less efficient CPM. Poor sleep quality along with higher levels of hypervigilance, pain catastrophising, and kinesiophobia were features of psychosocial profile of these patients.

Botulinum toxin type A applications for masticatory myofascial pain and trigeminal neuralgia: what is the evidence regarding adverse effects?

OBJECTIVES: The objective of the study was to conduct a systematic review of literature assessing botulinum toxin type A (BoNT-A) safety and adverse effects in the treatment of myofascial pain (MFP) and trigeminal neuralgia (TN). MATERIALS AND METHODS: The search for articles by two specific researchers involved the PubMed, EMBASE, Web of Science, and Scopus databases. Specific terms were used, and no publication time and language restrictions were applied. Clinical trials that investigated the effects of BoNT-A among participants with myofascial pain in masticatory muscles or trigeminal neuralgia were considered eligible for this systematic review. Data for each study were extracted and analyzed according to a PICO-like structured reading. RESULTS: The search strategy provided 436 citations. After analysis, 16 citations were included, seven for MFP and nine for TN. In all studies, BoNT-A was well tolerated and improved pain. The most common adverse effects were temporary regional weakness, tenderness over the injection sites, and minor discomfort during chewing. Most studies reported a spontaneous resolution of adverse effect. CONCLUSIONS: It can be concluded that BoNT-A treatment is well tolerated, since minor adverse effects were the most frequently reported; however, it is recommended that future studies aim to assess the safety and possible adverse effects of multiples applications or high doses of this treatment. CLINICAL RELEVANCE: BoNT-A has been increasingly diffused in dentistry, being used for the management of masticatory myofascial pain and trigeminal neuralgia. Nonetheless, there is no consensus about its efficacy and adverse effects that could occur when this treatment is applied.

Prevalence of psychosocial impairment in temporomandibular disorder patients: A systematic review.

BACKGROUND: Several studies have described high levels of psychosocial disorders in patients with temporomandibular disorders (TMD), but an estimate of their prevalence in populations of TMD patients has never been assessed systematically. OBJECTIVE: To conduct a systematic review of the literature on the prevalence of research diagnostic criteria for TMD (RDC/TMD) Axis II findings in TMD patients. METHODS: Search for articles was carried out by two independent researchers to retrieve papers published after 1992. Inclusion was reserved to observational studies with a minimum sample size of 100 individuals, which used RDC/TMD diagnostic protocol. Quality assessment was performed with the adoption of the methodological evaluation of observational research (MORE). RESULTS: A total of 1186 citations were obtained from search strategy, but only 14 filled the inclusion criteria. Included papers reported somatisation, depression and/or pain-related disability prevalence or scores from populations of 12 different countries. A broad range in the prevalence of moderate-to-severe somatisation in patients with TMD was observed, ranging from 28.5% to 76.6%. Similar results were found for depression, with moderate-to-severe levels in 21.4%-60.1% of patients. Finally, most patients were rated as grade I or II of the Graded Chronic Pain Scale, whereas high pain-related impairment was present in 2.6% to 24% of the individuals. CONCLUSION: The prevalence of severe-to-moderate somatisation and depression was high in TMD patients, while severe physical impairment was not commonly reported.

Is there enough evidence to use botulinum toxin injections for bruxism management? A systematic literature review.

OBJECTIVE: The objective of the study was to conduct a systematic review of the literature assessing the effects of botulinum toxin (BoNT-A) injections in the management of bruxism. MATERIALS AND METHODS: Search for articles involved the PubMed, Scopus, Web of Science, Embase, Cochrane, Scielo and Lilacs databases. Specific terms were used and the search carried out from 1980 to March 2016 by three independent researchers. Randomized controlled studies (RCTs), prospective and before-after studies that applied BoNT-A at the masseter and/or temporalis muscles were included. RESULTS: Three RCTs and two uncontrolled before-after studies out of 904 identified citations were included in this review. All five articles dealt with sleep bruxism and featured a small sample size. None of them was about awake bruxism. Two randomized clinical trials were double-blinded, with a control group using saline solution. Two studies used polysomnography/electromyography for sleep bruxism diagnosis, whilst others were based on history taking and clinical examination. All studies using subjective evaluations for pain and jaw stiffness showed positive results for the BoNT-A treatment. In contrast, the two studies using objective evaluations did not demonstrate any reduction in bruxism episodes, but a decrease in the intensity of muscles contractions. CONCLUSION: Despite the paucity of works on the topic, BoNT-A seems to be a possible management option for sleep bruxism, minimizing symptoms and reducing the intensity of muscle contractions, although further studies are necessary especially as far as the treatment indications for bruxism itself is concerned. CLINICAL RELEVANCE: BoNT-A has been increasingly diffused in dentistry over recent years, being also used for pain management in patients with bruxism. Nonetheless, there is no consensus about its effects in this disorder.

Botulinum toxin-A effects on pain, somatosensory and psychosocial features of patients with refractory masticatory myofascial pain: a randomized double-blind clinical trial.

The antinociceptive effect of BoNT-A have been well documented in animal studies; however, results of few but well-designed randomized placebo-controlled clinical trials about BoNT-A efficacy in masticatory myofascial pain (MFP) are inconsistent. Therefore, the present randomized, double-blind, placebo-controlled clinical trial evaluated the efficacy of BoNT-A in patients with refractory MFP. Twenty-eight patients with pain reduction of less than 30% despite conservative treatment and with an average pain intensity of > 50 mm on the visual analogue scale (VAS) participated. Patients were randomly assigned to receive a total of 80 U of BoNT-A or saline solution (SS) injected into the masseter and anterior temporalis muscles. Pain intensity (VAS), quantitative sensory testing (QST), conditioned pain modulation (CPM), and psychosocial status were examined. Follow-up was performed at 1 and 6 months. For repeated-measure comparisons between evaluation times, Friedman test with Bonferroni correction was used for pain and somatosensory variables and the Wilcoxon test for the psychosocial variables. The Mann-Whitney test was used for all comparisons between groups. The BoNT-A group had a significant decrease in pain intensity at follow-ups compared with the SS group (p < 0.001). QST assessment revealed higher pressure pain threshold values in the masseter muscle for BoNT-A group compared to SS (p < 0.03) at all follow-ups. No differences were found for mechanical pain threshold and wind-up ratio values (p > 0.05) in the entire study. The BoNT-A group presented the most efficient CPM effect (p < 0.03) only at the 1 month follow-up in the masseter muscle. There was a significant time effect for BoNT-A in all psychosocial variables (p < 0.05) and a drug effect in the Central Sensitization Inventory (p < 0.01), Pittsburgh Sleep Quality Index (p < 0.004), and Healthy Survey 36 (p < 0.05) at 6 months follow-up. The study demonstrates that a single injection-session of BoNT-A has positive effects on the hall pain spectrum of patients with refractory masticatory myofascial pain.

Somatosensory and psychosocial profile of migraine patients: A cross-sectional study.

BACKGROUND: Migraine is a chronic neurological disorder that involves the brain, characterized by a series of abnormal neuronal networks interacting at different levels of the central and peripheral nervous system. Furthermore, it is known that psychosocial features contribute to the exacerbation and chronicity of symptoms. OBJECTIVE: To compare the somatosensory and psychosocial profiles of migraine patients with a control group. METHODS: We conducted a cross-sectional study comparing the somatosensory and psychosocial profiles of patients with migraine and healthy volunteers. A total of 52 women were included. For the somatosensory profile, Mechanical Detection Threshold (MDT), Pressure Pain Threshold (PPT), Temporal Summation (TS), and Conditioned Pain Modulation (CPM) in the trigeminal and extra-trigeminal areas were evaluated. Psychosocial profiles were assessed using questionnaires, the Central Sensitization Inventory, the Generalized Anxiety Disorders, the Pain Catastrophizing Scale, and the Tampa Scale of Kinesiophobia. Mann-Whitney U test was used to compare differences in the profiles between groups. The significance level was set at 5%. RESULTS: Migraine patients showed a loss of somatosensory function in the trigeminal area for MDT (p = 0.019, r = 0.34 and p = 0.011, r = 0.37 for the ophthalmic nerve and masseter muscle respectively), lower PPT in trigeminal and extra-trigeminal areas (p < 0.001, r=>0.60) and less efficient CPM (p < 0.001, r=>0.60). No statistically significant differences were found in the TS (p=>0.05). Statistically significant differences were found in all psychosocial variables (p = <0.001 r=>0.60). CONCLUSION: Migraine patients showed loss of somatosensory function, lower pressure pain threshold, and an inhibitory pro-nociceptive profile with high scores on central sensitization and fear of movement compared to the control group.

Influence of the radius of Monson's sphere and excursive occlusal contacts on masticatory function of dentate subjects.

OBJECTIVE: To determine the influence of the radius of Monson's sphere, the number of posterior laterotrusive, mediotrusive, and protrusive contacts, and the chewing rate on food comminution. DESIGN: Sixty healthy dentate subjects, aged 21.22 ± 2.30 years, were selected. The three-dimensional coordinates of the cusp tips of the lower canine, premolar, and molar teeth were identified from the subjects' digital models. Monson's sphere was designed using the simplex method for function minimisation by adjusting the coordinates on its surface. The contacts were verified using 12 µm metal strips in jaw excursions at 0.5, 1.0, 2.0, and 3.0 mm. The masticatory performance and efficiency, swallowing threshold, and chewing rate were assessed through particle size fractionation. Data were analysed with multiple linear regression (α = 0.05). RESULTS: The sphere's radius, laterotrusive and protrusive contacts at 0.5 mm, and chewing rate were found to be negative predictor variables for masticatory performance until 20 chewing cycles (R2 = 0.429). For 40 cycles, the radius and total contacts (0.5 mm) were also explanatory factors (R2 = 0.223). Only the radius (R2 = 0.176) and the chewing rate (R2 = 0.082) were found to be significant for 60 cycles and swallowing threshold, respectively. Masticatory efficiency was influenced by masticatory performance until 40 and 60 cycles, as well as the radius and total contacts at 2.0 and 3.0 mm (R2 = 0.958). CONCLUSION: A larger radius of Monson's sphere and a greater number of posterior excursive contacts were found to be related to better masticatory function.

Trial data for precision analysis of a three-dimensional mandibular mechanical advantage.

The data presented in this manuscript describe craniofacial landmark coordinate values, muscle and load moment arm lengths, and mechanical advantage rates for constructing a three-dimensional model of masticatory muscles. Cone-beam computed tomography scans from 30 subjects (aged 12-19 years, 16 females) were used. Thirty-six craniofacial landmarks were identified. Subsequently, the moment arms for 7 muscles and their corresponding load moment arms at incisor and molar positions were determined. Then, the three-dimensional mechanical advantage for each muscle and tooth position was calculated as the ratio of muscle moment arm to load moment arm. This procedure was repeated three times by a main examiner and once by two other examiners. The Friedman test and the square root of the 'method of moments' variance estimator were used to compare data among examiners and calculate random errors, respectively. Although the values for the craniofacial landmark coordinates and biomechanical variables are very close, differences were found between measurements, especially in the interexaminer comparisons. Values served as the basis for reliability (intraclass correlation coefficient) and errors (average mean of absolute differences) analysis in the research paper titled "A three-dimensional method to calculate mechanical advantage in mandibular function: Intra- and interexaminer reliability study," published in the Journal of Orofacial Orthopedics.

Exploring botulinum toxin's impact on masseter hypertrophy: a randomized, triple-blinded clinical trial.

The present study aimed to assess the effectiveness and functional adverse effects of a single and multiple injections of botulinum toxin A (BoNT-A) for masseter hypertrophy (MH). Twenty-six women complaining about lower third facial enlargement due to MH, received 75 U of BoNT-A (abobotulinum toxin) in each masseter muscles. After 3 months, patients were randomly assigned to receive a second treatment session of Saline Solution: (G1; n = 11) or BoNT-A: (G2; n = 12). Muscle thickness (ultrasound), electrical activity (electromyography; EMG), masticatory performance, and subjective perception of MH were evaluated. Follow-up was performed at 1, 3 and 6 months. Muscle thickness, EMG activity, and masticatory performance were analyzed using ANOVA two-way and Sidak test as post-hoc. Masticatory performance was analyzed by the Friedman's test and Mann-Whitney test. Regarding inter-groups comparisons, there was a significant decrease in the left masseter muscle thickness in the G2 group at the 6 month follow-up (p < 0.02). For EMG, significant differences were evident at the 6 month assessment, with higher masseter activity for G1 (p < 0.05). For masticatory performance, no significant differences were observed throughout the study (p > 0.05) and a higher improvement in subjective perception of MH was observed in the 1 month follow-up for G2 (p < 0.05). In conclusion, BoNT-A is effective for MH, however multiple injections cause functional adverse effects in masseter muscle.