Effects Of Bioglass Combined With Laser On Dentinal Surface-an In Vitro Study

Dentine hypersensitivity is almost ubiquitous in hard dental tissue,to which various methods are available in accordance with hydrodynamic theory.such as bioactive glass、fluoride desensitizer、laser treatment and so on,all of which come into effect to some extent.Nevertheless,when combined with laser,bioactive glass is whether or not impactful all the same remains sealed.In this in vitro study,coupling bioactive glass with laser,we detect if desensitizing effects have been enhanced and assess the bonding outcome of the processed dentinal surface additionally.All that mentioned above aim at the acquisition of the best desensitizing treatment,the exploration of the desensitizing mechanism and the extensive appliance to clinic as well.Part Ⅰ Occluding effect of bioactive glass combined with Er laser irradiation on dentinal tubules:An in vitro studyObjective:To evaluate the occluding effect of bioactive glass combined with Er laser irradiation on dentinal tubules.Methods:45 dentine discs were prepared and etched with 0.5 mol/L EDTA.They were randomly divided into 5 groups:Group A(without treatment as control),Group B(treated with bioactive glass),Group C(treated with Er,Cr:YSGG laser irradiation),Group D(bioactive glass followed by Er,Cr:YSGG laser irradiation),Group E(Er,Cr:YSGG laser irradiation followed by bioactive glass).The occluding effect and mineral precipitate were inspected with scanning electron microscopy(SEM)and X-ray energy spectrum analysis(EDXA).Results:Micrographs of SEM demonstrated apparent occluding effect in Group B,C,D and E,with the best outcome in Group D,and the dentinal tubule exposure rates were Group D<Group E<Group C,B<Group A(P<0.001).EDXA manifested that special mineral content "Si" emerged in Group B,D,E.Conclusions:Bioactive glass combined with Er laser irradiation showed better occluding effect on the sensitive dentine model.Part Ⅱ The effect of bioactive glass combined with Er laser desensitizing treatment on bond strength to dentinObjective:To evaluate the effect of bioactive glass combined with Er laser desensitizing treatment on bond strength to dentin.Methods:The occlusal surface of 55 extracted teeth was flattened and adequate area of dentin was exposed,then etched with 0.5mol/L EDTA.They were randomly divided into 5 groups.Group A(without treatment as control),Group B(txeated with bioactive glass),Group C(treated with Er,Cr:YSGG laser irradiation),Group D(bioactive glass followed by Er,Cr:YSGG laser irradiation),Group E(Er,Cr:YSGG laser irradiation followed by bioactive glass).The prepared surface was bonded with resin.The shear bond strength was measured and data were analysed by SPASS17.0 statistic software.Transformation on dentin surface after diverse desensitizing preparation was observed by scanning electron microscopy(SEM).Results:The shear bond strength showed no variance after Er laser irradiation(P>0.05),whereas in the other groups shear bond strength reduced(P<0.05).Conclusions:The bond strength stabilized after Er laser irradiation.But experiencing the desensitizing treatment of bioactive glass together with Er laser,it would decrease.PartⅢ Occluding effect of two kinds of Er laser on dentinal tubules:An in vitro studyObjective:To evaluate the occluding effect of two kinds of Er laser on dentinal tubules.Methods:27 dentine discs were prepared and etched with 0.5mol/L EDTA.They were randomly divided into 3 groups with different treatments.Group A(without treatment as control),Group B(treated with Er:YAG laser irradiation),Group C(treated with Er,Cr:YSGG laser irradiation).The occluding effect was investigated with scanning electron microscopy(SEM).Results:Micrographs of SEM indicated distinct occluding effect in Group B,C.There were no diversification between the dentinal tubule exposure rates of Group B(4.186%±0.723%)and C(3.798%±0.843%),but they both were lower than A(33.610%±7.545%).Conclusions:The two kinds of Er laser could block dentinal tubules distinctly,but there were no difference between them.