Musculoskeletal disorders among dental students: a survey from Saudi Arabia.

BACKGROUND: Work-related musculoskeletal disorders (WMSD) are injuries affecting bones, joints, muscles, and tendons due to improper working conditions with serious consequences on health and career. Dentists were found to be at greater risk of developing WMSD compared to other healthcare providers. This study aimed to investigate the prevalence and risk factors of WMSD among dental students in Saudi Arabia. METHODS: This cross-sectional survey-based study recruited dental students across the kingdom using respondent-driven sampling technique. Data was collected using the Nordic Musculoskeletal scale and a validated, self- administered, close-ended questionnaire which assessed WMSDs predisposing factors, enabling factors and musculoskeletal disorders consequences and management. The questionnaire was administered in both Arabic and English languages and was distributed online using google forms. Data analysis was performed using SPSS, Chi-square test or Fisher Exact test was used where appropriate and Multivariate Logistic regression analysis was performed to identify predictors of developing WMSDs. RESULTS: The prevalence of WMSD was 87% (95% CL; 83.9% to 90.3%) among the 462 respondents. Gender, study year, type of practice, having clinics for left-handed, hours of clinical practice, sitting in the proper position while working, use of coping strategies were significantly associated with WMSD prevalence (P < 0.05). Males were OR = 10 times at higher risk of WMSD compared to females (P = 0.0001). Those with daily clinical practice were OR = 5 times at higher risk of WMSD than those who have weekly practice. Those practicing walking, workout, and yoga showed lower prevalence of WMSD (OR = 0.377 & 0.323, p = 0.015, 0.010 respectively). CONCLUSIONS: The prevalence of WMSD among dental students in KSA was high. Males and those with prolonged clinical sessions were at greater risk of WMSD. There is a need for awareness campaigns to educate dental students about risk factors of WMSD. Collegesy, dental colleges should adopt policies in reducing WMSD among their students.

Effect of Curvature Location on Fatigue Resistance of Five Nickel-titanium Files Determined at Body Temperature.

INTRODUCTION: The purpose of this study was to evaluate the effect of 5 different curvature locations on the fatigue resistance of thermomechanically treated nickel-titanium (NiTi) files and superelastic NiTi files at body temperature and to document the corresponding phase transformations. METHODS: EndoSequence (ES; Brasseler USA, Savannah, GA), EndoSequence CM (ESCM, Brasseler USA), K3 (SybronEndo, Orange, CA), K3XF (SybronEndo), and Vortex Blue (VB; Dentsply Tulsa Dental Specialties, Tulsa, OK) NiTi files (size 25/.04) were subjected to fatigue tests inside customized artificial canals containing a curvature of 60° and a 3-mm radius. There were 5 different canals based on the location of initial curvature; these included groups in which the distance between the canal orifice and the location of the curvature (DOC) was 5, 6, 8, 10, and 11 mm. The model canal was immersed in water at 37°C ± 1°C. The number of cycles to failure (Nf) was recorded, and the fracture surface of the fragments was examined by scanning electron microscopy. Two unused files of each brand were examined by differential scanning calorimetry. RESULTS: The Nf was highest in the 10-mm and 11-mm DOC groups and lowest with the 5-mm and 6-mm DOC groups (P < .05). ESCM files had the highest fatigue resistance followed by the VB, K3XF, K3, and ES files (P < .05). ESCM files had the highest Nf (P < .05), and ES and K3 files had the lowest Nf (P < .05) depending on the curvature location. Two endothermic peaks were observed on the heating curve of the heat-treated files (ESCM, K3XF, and VB). CONCLUSIONS: The location of the canal curvature had a significant effect on the fatigue resistance of both heat-treated and superelastic NiTi files. The fatigue life of files in the coronal curve was quite short.