comparison of new and 3-month-old tooth brushes in the removal of bacterial plaque in ahvaz dental school student 1388-89

background there is inconclusive evidence about the relationship between toothbrush wear and plaque removel. the aim of this study was to compare the effectiveness of new and 3 month-old toothbrush in the removal of dental plaque. material and methods in a randomized single blind clinical trial 63 students attended from awaz dental school. subjects were divided to three groups. plaque was scored pre-brushing and post brushing new toothbrushes using the turesky et al index. after 3 months, plaque was rescored pre-brushing and post-brushing 3-month–old brushes following 48h periods of no oral hygiene. collected data analyzed using paired-t-test and anova. results all 60 subjects compelated this study. both the new and 3-month-old brushes reduced plaque scores significantly than pre-brushing time. the percentage reductions in plaque scores achieved with the new brushes were not significantly different from those achieved with 3-month-old brushes from total surfaces. compared with 3 type toothbrushes, no significant different were found for plaque score reduction with the new and 3-month-old brushes.