Abstract:Both physicians and patients have paid more and more attention to xerostomia,possibly because of improvements in modern medicine and the demands of high quality life.There is a certain correlation between xerostomia and oral local or systemic diseases,although it is not a specific disease.By expatiating the definition,causes,clinical evaluations,disease prevention and treatments of xerostomia,this review aims to instruct physicians to systematically master and properly implement clinical assessments and countermeasures,so as to improve the clinical therapeutic effect.

Abstract:In clear removable thermoplastic appliance at-tachments can be used for retention of the aligner as well as to enhance or facilitate specific tooth movements. This artice in-troduce in detail the definition,classification and clinic appli- cation of attachment,review the attachemnt relative study, show the recent attachemnt research result. The addition of at-tachments increases a tooth’s geometric mass and enhances the undercuts along a horizontal plane,which should aid tooth movement.

Abstract:Calcium hydroxide gets more and more used in the disinfection of root canal for its unique physical and chemi-cal properties. Many studies show that calcium hydroxide has good diffusivity and can produce the disinfection effect by destroying bacteria and degrading lipopolysaccharide(LPS). This article will make a review on the mechanism of calci-um hydroxide in disinfection of root canal.