ABSTRACT
This cross sectional study has bees done in nine randomly selected Kindergartens of Mashhad. The purposes of this research were to obtain prevalence of bruxism and it's relationship with dental complications, and temporom and ibular disorders in 3-6 year-old children. 70 [9%] out of 772 [3-6 year-old] children had bruxism in view of parent's reports and oro-dental examinations. The most current age for the spreading bruxism was 4-5 years-old [37.1%]. All affected children had nightly bruxism. In 35/5% of affectes children and in 11.1% of unaffected children family histories were positive. In 38/5% of affected children and in 54.1% of unaffected children, mother had a job. In 75.5% of affected children there were no dental problems, pain in facial muscles or at jaw opening observed. In 4.2% of the children there pain on was temporom and ibular joint movement