Backgrounds and Objective:Teeth color change after fixed orthodontic treatment which often affects patients to evaluate the comprehensive effect after orthodontic.Many patients require to some beauty treatment to improve their teeth color for their dissatisfaction with their teeth color after fixed orthodontic treatment.Literature about discoloration before and after fixed orthodontic treatment have been reported.However,there has less reported that the related reason why teeth color change after fixed orthodontic treatment and related treatments.Therefore,we will simulate the process of fixed orthodontic with bracket bonding and debonding,to analyze and discuss the effect of different adhesive types and treatments on teeth surface roughness and teeth color.The purpose of the study is to provide reference for preventing and treating the discolored teeth after fixed orthodontic.Methods:1.Choose 117,A2 in vitro teeth which were divided into group A(bracket bonding with chemical curing resin),group B(bracket bonding with light-cured resin),and group C(not bonding).There are 39 teeth in every group.Three groups of samples were immersed in water,constant temperature of 37 °,2 days.Two days later,brackets of group A and group B were debonded.Three groups randomly selected 3 in vitro teeth in each group to observe with scanning electron microscope.2.There were the rest of 36 in vitro teeth in group A,group B,and group C,respectively.They were immersed in artificial stain for seven days.Teeth color measured with spectrophotometer in the third buccal surface before and after dyeing.And then the values of L*,a*,and b* were recorded.3.Group A,group B,and group C were randomly divided into three subgroups after dyeing.There were sandblasting subgroup,bleaching subgroup,and blank control subgroup in each group.Every group had 12 in vitro teeth.Sandblasting subgroup:sandblasting machine sandblasted 20 seconds away from tooth surface 3 mm,45 ° Angle.Bleaching subgroup: tooth surface with 35% hydrogen peroxide bleaching gel about 2 to 3mm thick,the light of cold light whitening instrument worked 3 times,each time 10 minutes.Blank control subgroup: untreated.Teeth color measured with spectrophotometer after sandblasting and bleaching,respectively.The values of L*,a*,and b* were recorded.4.Every 3 in vitro teeth were randomly selected in group A,group B,and group C after sandblasting and bleaching.And then they were observed with scanning electron microscope.Results:1.The results of scanning electron microscope:(1)The surface roughness results of group A,group B,and group C after brackets debonding: group A > group B > group C.(2)The surface roughness results of stained teeth in group A,group B and group C after different treatments: sandblasting > bleaching > blank control.The surface roughness results of group A,group B,and group C after sandblasting and bleaching: group B >group A > group C.2.The results of color parameter measurements:(1)L* value was reduced,a* and b* values were increased after in vitro teeth dyeing in group A,group B,and group C.Compared three groups of two,a *,b * variation and color difference(Δa*,Δb*,ΔE)all had differences,group A > group B > group C.There had no statistically significant difference of L* variation(ΔL*)between Group A and group B.There had statistically significant difference between group C and group A,group B,and group A and group B > group C.(2)A factor of adhesive types(group A,group B,group C)and B factor of treatment(sandblasting,bleaching,blank control)all affected ΔL*,Δa*,Δb*,and ΔE of teeth color,in addition to the effect of adhesive types on ΔL*,and there were interactive effect between with the two factors.Compared group A,group B,and group C of two,there had no statistically significant difference of Δa*,Δb*,and ΔE.However,there had statistically significant difference between group A and group C,group B and group C,and group C >group A and group B.Compared sandblasting,bleaching,and blank control of two,there had statistically significant difference of ΔL*,Δa*,Δb*,and ΔE,and bleaching >sandblasting > blank control.The values of ΔL*,Δa*,Δb*,and ΔE were maximum in group C after bleaching.L* value was increased,a* and b* values were reduced after sandblasting and bleaching.Conclusions:1.Under this experimental condition,the effect of different bracket adhesives on teeth surface roughness and color after debonding are different.Roughness of light-cured resin adhesive group is little and not easy to dye,which can reduce teeth discoloration afterbracket debonding.2.Application of different bracket adhesives is related to surface roughness after sandblasting or bleaching.The surface roughness of chemical curing resin adhesive group is less than light-cured resin adhesive group after sandblasting or bleaching.3.Application of sandblasting and bleaching which increase teeth surface roughness of every group,however the color improved.The short-term improvement effect of bleaching is obviously superior to sandblasting.4.A preliminary advice for clinic is to choice chemical curing resin adhesive for bracket bonding,bleaching for beautifying teeth color after bracket debonding,and polishing technology for consolidating the curative effect,which will provide reference for teeth color beauty after fixed orthodontic. |