Effects of muscle pain induced by glutamate injections during sustained clenching on the contraction pattern of masticatory muscles

Radiographic Assessment of Pediatric Condylar Fractures after Conservative Treatment with Functional Appliances-A Systematic Review

Background: To evaluate the effectiveness of conservative treatment with functional appliances for condylar fractures in pediatric age. Methods: Four electronic databases (PubMed, EBSCO, Scopus, and Web of Science) were consulted with no restriction of publication status or year, up to 31 August 2020. Selection criteria: based on the PICOS criteria, the selection criteria were set for observational human studies, with at least 10 patients and six months of follow-up. The study population included pediatric patients (aged 5–16 years), with unilateral or bilateral condylar fracture, treated with functional appliances. Condylar remodeling and mandibular growth were analyzed through sequential radiographic examinations. Data collection and analysis: Two independent reviewers carried out title-abstract screening, and a senior investigator was involved to solve any disagreement. The quality of the evidence was assessed through the Canada Institute of Health Economics (IHE) quality appraisal checklist, and the National Institutes of Health (NIH) quality assessment tool. Results: A total of 971 articles were retrieved from the electronic search; among them, three studies met the eligibility criteria. A moderate risk of bias was detected in all the studies, due to common limitations (absence of multicenter studies, prospective design, blindness of the investigators, patients’ drop-out). At follow-up examinations (between 6 months and 4.9 years), the difference of condylar neck length between the “injured” and “healthy” side was approximately 2 mm, while the anteroposterior condylar width discrepancy was recorded up to 1 mm. Conclusions: Short- and long-term data revealed that conservative treatment with functional appliances led to partial or full radiological recovery of the joint morphology, along with good to excellent functional results. Patients’ age has a crucial role on the treatment choice, and the type of fracture (presence of condylar displacement, or dislocation) is also a major prognostic indicator of the radiologic outcome. Limitation: To confirm the effectiveness of functional appliances, more prospective clinical long-term follow-up studies with homogeneous samples of condylar fractures are deemed necessary. Registration: The study protocol was registered on PROSPERO (CRD42020205650).

Effect of experimental anterior temporalis muscle pain on jaw movements

To test the hypotheses that experimental noxious stimulation of the anterior temporalis muscle results in significant decreases in jaw movement amplitude and velocity, and there are significant correlations between scores of mood or pain-related cognitions and amplitude and velocity. The jaw movements of 14 asymptomatic participants were recorded during standardised open/close jaw movements and free and standardised chewing tasks. Tonic infusion of hypertonic saline into the right anterior temporalis muscle maintained pain intensity between 40 and 60 mm on a 100-mm visual analogue scale. Tasks were performed in a single session in the following sequence: baseline condition, test 1 condition (during hypertonic or isotonic saline infusion), test 2 condition (during saline infusion) (10-min rest between conditions). Participants completed the Depression, Anxiety and Stress Scale (DASS-21) and the Pain Catastrophizing Scale (PCS). Amplitude and velocity of opening and closing were compared between conditions with a repeated-measures analysis of variance (anova), and Spearman's rank correlation coefficient explored correlations; statistical significance: P < 0·05. For any of the three tasks, there were no significant differences in kinematic variables between any condition and no significant correlations between DASS-21 or PCS scores and kinematic variables during hypertonic saline infusion. The absence of a significant reduction in velocity or amplitude of open/close or chewing jaw movements during experimental temporalis muscle pain is not consistent with the Pain Adaptation Model proposing decreases in kinematic measures in pain. The lack of significant correlations between psychological variables and measures of jaw movement may reflect the low scores reported by our study sample.

Effect of somatosensory amplification and trait anxiety on experimentally induced orthodontic pain

The perception of pain varies considerably across individuals and is affected by psychological traits. This study aimed to investigate the combined effects of somatosensory amplification and trait anxiety on orthodontic pain. Five-hundred and five adults completed the State Trait Anxiety Inventory (STAI) and the Somatosensory Amplification Scale (SSAS). Individuals with combined STAI and SSAS scores below the 20th percentile (LASA group: five men and 12 women; mean age ± SD = 22.4 ± 1.3 yr) or above the 80th percentile (HASA group: 13 men and seven women; mean age ± SD = 23.7 ± 1.0 yr) were selected and filled in the Oral Behaviors Checklist (OBC). Orthodontic separators were placed for 5 d in order to induce experimental pain. Visual analog scales (VAS) were administered to collect ratings for occlusal discomfort, pain, and perceived stress. Pressure pain thresholds (PPT) were measured. A mixed regression model was used to evaluate pain and discomfort ratings over the 5-d duration of the study. At baseline, the LASA group had statistically significantly higher PPT values for the masseter muscle than did the HASA group. During the experimental procedure, the HASA group had statistically significantly higher discomfort and pain. A significant difference in pain ratings during the 5 d of the study was found for subjects in the HASA group. Higher OBC values were statistically significantly positively associated with pain. Somatosensory amplification and trait anxiety substantially affect experimentally induced orthodontic pain.