Inhibitory Effect of Application of Crystal Violet Solution and Yellow He-Ne Laser Irradiation on Coronal Plaque Formation in Rats

The purpose of this study was to evaluate the inhibitory effect of the application of crystal violet solution (0.8mg/l: CV) and yellow He-Ne laser irradiation (4.3 mW, 594 nm : laser) on dental plaque formation on posterior tooth surfaces in rats. Twenty-four 22-23-day-old female Donryu rats were used, and divided into 4 groups. The right and left maxillary 1st molars of the rats in each group were assigned to one of the following 4 treatment groups: 1) He-Ne + CV group-application of CV plus laser irradiation (25 sec, 3 times daily for 2 weeks period) ; 2) He-Ne group-laser irradiation alone; 3) CV group-application of CV alone, and 4) Control group-no application of CV or laser irradiation. Three rats in each group were sacrificed 1 week and 2 weeks later. Inhibitory effecton plaque formation on the maxillary left 1st molars was assessed by stereomicroscopy and scanning electron microscopy. The upper right 1st molars were evaluated histologically. The thickness of the plaque on the section was measured under a microscope. At 1 week, the inhibitory effect on plaque formation in the He-Ne+CV group was statistically less than in He-Ne, CV, and control, the groups. Howevery there were no statistically significant differencs in inhibitory effect on plaque formation between the groups at 2 weeks. The results indicate that application of CV and laser irradiation may be a useful method of inhibiting early plaque formation.