Background and objectives: Work-associated musculoskeletal disorders have become a common phenomenon and can happen over time as a result of exposing to workload repeatedly. Common regions that vulnerable to include Work-associated musculoskeletal disorders the neck and lower back. The objectives of the study were to assess the prevalence, causes, severity, and extent of lower back and neck pain among the dentists in Erbil city. Methods: A cross-sectional study was done among on dentists of three medical universities of Erbil. Data collection was performed using a self-stated questionnaire with items related to socio-demographic characteristics, time in profession, activities performed and work conditions. Results: the results showed that the neck and back pain is prevalent by 55% and 66% respectively. The neck and back pain seems to decrease with the year of experience. Overweight dentists seem to be exposed to neck and back pain more than normal and obese participants. The study also showed that 91% of the participants seem to do no assistive tools to reduce the pain. Individual factors height and weight and work position are important risk factors for neck and back pain. Conclusions: Vast majority of the participants somehow complain from neck and back pain regardless of weight, height and working position. But the pain attenuates with increasing experience. Also, majority of the participants take no assistive tools to reduce neck and back pains.

Samaraie (2) ; Fahd S. Ikram (3) Background and objectives: Radiolucency of poly methyl methacrylate denture base resin is of great concern, and many approaches have been used to make acrylic resin dentures more radiopaque.The purpose of this study was to prepare a modified heat cure ploy methyl methacrylate denture base resin by incorporation of different weight percentages (2%, 3%, 4%, 5%, and 6%) of CaCO3 nanofiller particles, to increase its radiopacity. Materials and methods: CaCO3 nanofiller particles (coated with a special coupling agent) were dispersed and sonicated in the acrylic monomer (liquid) in different percentages, then mixed with acrylic powder. For each test 60 specimens were prepared, the specimens were divided into 6 groups (10 for each) coded I to VI. Group I was the control group (unmodified specimens), the remaining five groups were reinforced with CaCO3 nanoparticles to achieve loading of 2%, 3%, 4%, 5%, and 6% by weight. Some physical properties were evaluated. Results: There was a slight change of color of the acrylic, in groups II, III and IV, but there was an obvious color change of group V and VI. Also, there was a highly significant increase in the radiopacity in groups IV, V and VI. Conclusion: Addition of 4% CaCO3 nanoparticles to the heat cure acrylic resin increases the radiopacity of the denture base significantly, without adverse effects on the color.