Dentists have a high occupational risk of neck disorders with impact on somatosensory function and neck mobility.

OBJECTIVES: Musculoskeletal disorders (MSDs) in the neck and shoulder region may be associated with significant impairment of quality of life and well-being. The study was to determine the prevalence of painful MSDs in Chinese dentists and evaluate somatosensory function and neck mobility compared with non-dental professional controls. METHODS: One hundred dentists (age: 36.5 ± 9.8 years) and 102 controls (age: 36.2 ± 10.0 years) were recruited between September 2019 and December 2020. The Medical Outcome Study 36-item short-form health survey questionnaire and information of MSDs history were recorded. The cervical range of motion (CROM) with and without pain, and the pressure pain thresholds (PPTs) of the facial and neck muscles were tested. Chi-square test, Mann-Whitney U test and multiple linear regression analysis were used to analyze the data. The factors in the multiple linear regression analysis were occupation, working age, and gender. RESULTS: The prevalence rate of neck pain was significantly higher in dentists (73.0%) compared with the controls (52.0%) (P = .002). The regression models of cervical range of posterior extension, lateral flexion and rotation were statistically significant (P ≤ .001). The regression models of PPTs of the tested facial and neck muscles were statistically significant (P < .001). CONCLUSION: Dentists are at higher risk of neck pain. The bigger cervical range of left rotation of dentists could be related to the working posture. The lower PPTs in dentists may reflect a hypersensitivity in the facial and neck muscles. Preventive measures are needed to reduce occupational hazards in dentists.

Effect of photobiomodulation therapy on painful temporomandibular disorders.

To evaluate the effect of photobiomodulation therapy (PBMT) on painful temporomandibular disorders (TMD) patients in a randomized, double-blinded, placebo-controlled manner. Participants were divided into a masseter myalgia group (n = 88) and a temporomandibular joint (TMJ) arthralgia group (n = 87) according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Both groups randomly received PBMT or placebo treatment once a day for 7 consecutive days, one session. The PBMT was applied with a gallium-aluminum-arsenide (GaAlAs) laser (wavelength = 810 nm) at pre-determined points in the masseter muscle (6 J/cm2, 3 regions, 60 s) or TMJ region (6 J/cm2, 5 points, 30 s) according to their most painful site. Pain intensity was rated on a 0-10 numerical rating scale (NRS) and pressure pain thresholds (PPT) and mechanical sensitivity mapping were recorded before and after the treatment on day 1 and day 7. Jaw function was assessed by pain free jaw opening, maximum unassisted jaw opening, maximum assisted jaw opening, maximum protrusion and right and left excursion. Data were analyzed with a mixed model analysis of variance (ANOVA). Pain intensity in arthralgia patients decreased over time (P < 0.001) for both types of interventions, however, PBMT caused greater reduction in pain scores than placebo (P = 0.014). For myalgia patients, pain intensity decreased over time (P < 0.001) but without difference between interventions (P = 0.074). PPTs increased in both myalgia (P < 0.001) and TMJ arthralgia patients over time (P < 0.001) but without difference between interventions (P ≥ 0.614). Overall, PBMT was associated with marginally better improvements in range of motion compared to placebo in both myalgia and arthralgia patients. Pain intensity, sensory function and jaw movements improve after both PBMT and placebo treatments in myalgia and arthralgia patients indicating a substantial non-specific effect of PBMT.