The Comparison Of Enamel Surface Roughness Following Interproximal Enamel Reduction (IER) With Different Instruments Before And After Polishing

ObjectiveTo compare the effect of different instruments of interproximal enamel reduction(IER)on enamel surface roughness before and after polishing.Methods60 healthy premolars were used after removal for orthodontic reasons and divided into six groups.Experimental group:Ⅰ～Ⅴ,Control group:VI.Each group underwent IER with different IER instruments,I:diamond burs(medium);II:diamond burs(fine);Ⅲ:hand-held diamond strips(medium);Ⅳ:hand-held diamond strips(fine);V:diamond discs.;Ⅵ:control group(no IER).One proximal surface of sample after IER was polished with Sof-Lex polishing discs.Striped and polished surface roughness was assessed and morphology was observed respectively using Laser scaning confocal microscopy(LSCM).Results1.Comparison of the enamel surface roughness in six groups after IER before polishing:I:0.582±0.134μm,II:0.456±0.059μm,Ⅲ:0.564±0.104μm,IV:0.3 15±0.052μm,V:0.233±0.039μm,VI:0.139±0.028μm,Group I and GroupIII had the roughest surfaces followed by group Ⅱ、IV、V,group V produced the smoothest results,and these surfaces were significantly rougher than the control surfaces.There was no statistically significant different between group I and groupIII(P=0.632),and there were statistically different among the other groups(P<0.05).2.Comparison of the enamel surface roughness in six group after polishing:I:0.052±0.014μm,II:0.055±0.018μm,III:0.061±0.012 μm,IV:0.059±0.015μm,V:0.054±0.011μm,The enamel surface roughness of the group I、II、III、IV、V decreased significantly,and these surface smoother than the control surfaces.There was no significant different between groups(P>0.05).3.LSCM image:The surface morphology of enamel in six groups after IER before polishing:group Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ all produced enamel furrows and scratches,group Ⅰ、Ⅱ created deeper furrows and scratches than Group Ⅲ、Ⅳ、Ⅴ,and group V produced the shallowest scratches.The surface morphology of enamel in five groups after polishing:Polishing with Sof-Lex polishing discs after IER basically eliminated the scratches that created by IER(no significant difference between groups I,II,III,IV and V).Conclusion1.Different IER instruments produced enamel surfaces different degrees of roughness,enamel surfaces treated with diamond burs(medium)and diamond strips(medium)were the roughest,followed by diamond burs(fine)、diamond strips(fine),and treated with diamond discs were the smoothest.2.All instruments produced enamel furrows and scratches after IER.Polishing with Sof-Lex polishing discs after IER basically eliminated the scratches,only leaving fine and shallow grooves.3.Polishing with Sof-Lex polishing discs after IER with different instruments reduced the enamel surface roughness,and these surfaces were smoother than untreated enamel.