Study On Adhesion Of Streptococcus Mutans To Zirconia Ceramic Brackets And Its Shear Bond Strength Using GC Fuji OrtHo LC Adhesive

Part 1 In vitro study on the microleakage and shear bond strength of zirconia ceramic brackets using GC Fuji Ort Ho LC adhesiveObjective: To evaluate the microleakage and shear bond strength of zirconia ceramic brackets using GC Fuji OrtHo LC adhesive.Methods: The experiment is divided into :zirconia ceramic brackets?alumina ceramic brackets?metal brackets.All of them were bonded to the extracted human premolars using GC Fuji OrtHo LC adhesive.The microleakages were measured by stereomicroscopy.The shear bond strengths were tested by a universal testing machine,and after the bracket was disengaged,the adhesive residual indexes(ARI values)were observed under a magnifying glass of 20 times.Results : There were no statistically significant difference in their microleakage(P>0.05).The shear strength of zirconia ceramic brackets was not significantly different from that of the alumina ceramic brackets(P>0.05),but both of them are higher than that of the metal brackets(P <0.05).All of the brackets' shear adhesive strengths were within the clinical application,and there were no significant difference in ARI(P>0.05).Conclusion : The microleakage depth between the zirconia ceramic brackets and enamel by GC Fuji OrtHo LC adhesive is not significantly different from that of the alumina ceramic brackets and metal brackets,but its shear bond strength is higher than that of the metal brackets.It can be used for clinical practice.Part 2 Study on adhesion of Streptococcus mutans to Zirconia ceramic bracketsObjective: To evaluate the impact of zirconia ceramic brackets on the adhesion of Streptococcus mutans.Methods:18 brackets were collected in the experiment,9 zirconia ceramic brackets in observation group and 9 alumina ceramic brackets in control group;after the brackets in both groups were cultured in the Brain Heart Infusion Medium with saliva for 72 hours,TaqMan probe method of real-time polymerase chain reaction was applied in analyzing quantitatively the amount of Streptococcus mutans and that of the total bacteria,thus the composition ratio of Streptococcus mutans was calculated;a comparative study in composition ratio of bacteria was given between the 2 groups.Results: There existed no statistical difference in composition ratio of Streptococcus mutans in total bacteria between the 2 groups(P>0.05)as well as in the amount of Streptococcus mutans and of total bacteria adhered to the brackets in the 2 groups(P>0.05).Conclusion: The adhesion of Streptococcus mutans and that of total bacteria to zirconia ceramic brackets is of no obvious difference from those of alumina ceramic brackets,which needs further clinical research.