Evaluation of ergonomic factors and postures that cause muscle pains in dentistry students' bodies.

BACKGROUND: Work-related musculoskeletal disorders commonly experienced by dental professionals are one of the main occupational health problem affecting their health and well-being.This study was conducted to evaluate ergonomic factors and profession-related postures and also investigate relationship between demographic factors and work condition with pain in dental students. MATERIAL AND METHODS: 60 freshman and sophomore dentistry students were randomly chosen as the subjects of control group, and 60 of 5th and 6th-year students were selected as the members of exposure group. Data related to the subjects such as sex, doing exercise, severity of musculoskeletal pain were obtained through questionnaire. Students' postures were directly observed while treating patients and they were scored by REBA method. Data were analyzed by SPSS software using Man-Whitney, Kruskal-Wallis, Spearman and Kendall correlation tests. RESULTS: 80.8% of the subjects were not aware of the correct ergonomic postures for dental procedures. Severity of musculoskeletal pain in the exposure group (15.9± 4.2) was significantly higher than the control group (10.5 ±3.2), (p <0.001). Risk of the most subjects (84%) was at the medium level. Students who were more involved in clinical activities experienced more muscular pains. CONCLUSIONS: The musculoskeletal disorders are probable prolonged in working hours in static positions, incorrect work postures, implying more force and even tools and instruments. Therefore, students who are aware of ergonomic principals of their own profession would be able to maintain their health through activities and lifelong. Key words:Posture, dentistry, students, musculoskeletal pain.

Crystal structure of 2,2,3,3-tetra-methyl-1,1,1,4,4,4-hexa-phenyl-tetra-germane.

The mol-ecule of the title compound, C40H42Ge4, lies with its central Ge-Ge bond on an inversion centre giving rise to a zigzag backbone of four tetra-hedrally coordinated Ge atoms. The symmetrically independent Ge-Ge bonds are slightly shorter than in other organo-tetra-germanes whereas the Ge-CPh (Ph = phen-yl) and Ge-CMe (Me = meth-yl) distances have their usual values. In the crystal, (010) layers of Ph6Me4Ge4 mol-ecules with a parallel orientation of the Ge4 backbone exist, held together by van der Waals forces only. Main bond lengths in organo-substituted oligogermanes are compared.

In silico Evaluation of Crosslinking Effects on Denaturant m(eq) values and ΔCp upon Protein Unfolding.

Important thermodynamic parameters including denaturant equilibrium m values (m(eq)) and heat capacity changes (ΔCp) can be predicted based on changes in Solvent Accessible Surface Area (SASA) upon unfolding. Crosslinks such as disulfide bonds influence the stability of the proteins by decreasing the entropy gain as well as reduction of SASA of unfolded state. The aim of the study was to develop mathematical models to predict the effect of crosslinks on ΔSASA and ultimately on m(eq) and ΔCp based on in silico methods. Changes of SASA upon computationally simulated unfolding were calculated for a set of 45 proteins with known m(eq) and ΔCp values and the effect of crosslinks on ΔSASA of unfolding was investigated. The results were used to predict the m(eq) of denaturation for guanidine hydrochloride and urea, as well as ΔCp for the studied proteins with overall error of 20%, 31% and 17%, respectively. The results of the current study were in close agreement with those obtained from the previous studies.