The Research Of The Nano-silver Contained Hydroxyapatite Coating Ceramic Bracket’s Mechanical And Anti-bacterial Properties

Objective:To develop a nano-silver containing hydroxyapatite coated ceramicbracket and to study the mechanical properties of the nano-silvercontaining hydroxyapatite coated ceramic bracket while the coating’s surfaceproperties，Ag ion release ability and anti-bacterial effect were also evaluated.Methods:Microplasma spraying was choosed to develop the nano-silvercontaining hydroxyapatite coated ceramic bracket and the coating’s surface propertieswere studied；40healthy human premolars extracted for orthodontic reasons werecollected and randomly divided into two groups(control group and experimental group)with20in each group.The teeth in experimental group were bonded with the coatedceramic brackets while the control group with the normal ceramic brackets. Anelectronic universal testing machine was used to evaluate the force applied to debondthe brackets, the value of Shear Bond Strength (SBS) and Adhesive Remnant Index(ARI) scores were recorded.Six nano-silver containing hydroxyapatite coated ceramicbrackets and six normal ceramic brackets were choosed， their Ag ion releaseconcentrations in artificial saliva were examined by Inductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES) at1、3、7、14、21days and the coating’santi-bacterial effect was tested by the coating film method.Results:1. The coating of this new type of antibacterial bracket has a good stabilityand an uniform thickness: about100μm, the SBS of the brackets were7.34±1.72MPa, which meet the clinical requirements and the average score of the ARIwas1.45. Both the value of SBS and the ARI scores were lower than the controlgroup,and the differences were statistically significant (P<0.01). 2. The coating’s Ag ion release concentration increased with time while therelease speed decreased with time, the structure become stable after14day and theanti-bacterial ratio was99.9%.Conclusion:The nano-silver containing hydroxyapatite coated ceramicbracket’s mechanical properties meet the clinical requirement while the coating’ssurface properties was also good，indicating that the bracket can decrease theincidence of enamel damage while debonding.The Ag ion release ability andanti-bacterial effect were also satisfied，both of which imply that the coating mayprevent enamel demineralization during orthodontic treatment.