[The influence of Streptococcus sanguis on corrosion resistance of magnetic retainer].

Purpose: To study the effect of Streptococcus sanguis on corrosion resistance of magnetic retainers in which are encapsulated with stainless steel artificial saliva.

Methods: A magnetic retainer was put in one culture flask,which was filled with artificial saliva.Ten of them were added Streptococcus sanguis suspension,the others were added PBS as control.

[The efficacy of dental plaque removed by using sonic electric toothbrush in children].

Purpose: To evaluate the efficacy of using sonic electric toothbrush to clean the teeth and control dental plaque in children.

Methods: 50 children aged 6 to 7 years old were selected and divided into 2 groups according to the use of sonic electric toothbrush and traditional manual toothbrush (control group). The numbers of dental plaque surface and PLI before and after tooth brushing were recorded.

[Analysis of conservative therapies for posterior teeth with longitudinal fractures.].

Purpose: To explore the ideal method for conservative therapies of posterior teeth with longitudinal fracture.

Methods: The records of 297 cases undergoing conservative treatment of posterior teeth with longitudinal fracture were analyzed regarding to the position, etiology and the time of treatment from fracture and the causes of failure.

Results: 258 cases were conserved effectively and 39 cases were extracted due to failure.