The Effect Of A Glass Ionomer Restoration Artificially Demineralized Dentine Caries In Vitro

Recurrent caries is one of the most important reasons for the failure of the caries therapeutic restoration for the modern operative dentistry. Removal of all caries tissue is key .In pathology, the top of dentine caries is only demineralized and no bacterium, it shall be left because it can be remineralized in satiating mineral content solution and .In the study of enamel caries, The glass ionomer cement have been tested that it can promot remineralized and inhibited demineralized enamel.The main structure of dentine and enamal is alike. The content of organic substance of dentine was more than of enamals. The purpose of this study is to establish the artificial dentine carise model in vitro and to estimat the ability of glass ionomer cement and resin -modified glass ionomer about promoting remineralized and inhibited demineralized dentine caries .The study can also supply theoretic evidence for avoiding recurrent caries in clinical practice and protecting live pulp in treatmeant of heavy dentine caries .Methods IThe establishment of an artificially dentine caries modelin vitro: Fifty-six human permanent lower premolars extracted for orthodontic reasons were selected for the study .Two same class V cavities were cut on the mesial and distal sides of each teeth respectively. The teeth were then immersed in a standard buffer solution to obtain caries -like wall lesions. Each tooth was dry at room temperature.2To set up the comparison group and the test group :One of the two cavities of each tooth was covered with the acid -resistant nail varnish and as the control groups, then the specimen were assigned randomly into four groups .Each groups (n=14),another cavities of each tooth were restored with the glass ionomer cement, the resin-modified glass ionomer, amalgam and ZOE.Each teeth was immersing in 20ml artificial saliva for 20h, then in acid buffer solution for 4h.The cyclic program was carried out for 28 days.3Scanning electron microphotography: Each tooth was sectioned perpendicular to the long axis of teeth alone the enamel-cemental junctions using a hardness tissue slicing machine. Observing the two sectioned side with 100 magnification for the junction of the dentine and the restoration. Then observing the morphology of dentinal tubule with 5000 magnification. Measured the content of calcium, phosphorus and fluoride using electron spectroscopy .The values of all the specimens were statistical analysis according to averaged parameter.Result lunder 100 magnification.The junction of the glass ionomer cement and dentine, the resin -modified glass ionomer and dentine have no microleakage, but the junctions of the amalgam and dentine , ZOEcement and dentine ,ZOE cement and the amalgam have clear microleakage (p<0.01)2 under 5000 magnification. The resin-modified glass ionomer, which demineralized peritubular dentine was covered with mineral substance ,but another test groups .the demineralized peritubular dentin were not changed.SThe change of the content of calicium, phosphorus, fluoride. The content of calicium, phosphorus, fluoride of the glass ionomer cement and resin-modified glass ionomer were more than the control group and anther two groups (p<0.01) . In another three groups ,the content of calicium, phosphorus, fluoride was not changed (p>0.05).Conclusion IThe artificial dentine caries which was made in the acid buffer solution was similar to the demineralized dentine caries in situ, which can be remineralized 2Glass ionomer remineralization and inhibiting demineralization of dentine carries in Vitro. The two restorative material have chemical adhesion to the dentine 3Amalgam and ZOE cement do not promote remineralization of demineralized of dentine caries in vitro and have microleakage with dentine.