Effect of carbamide peroxide bleaching agents on the surface roughness of enamel in vitro

WANG Xiao-ling; HE Hui-ming; ZHAO Xin-yi; WANG Zhong-yi

Abstract：AIM: To evaluate the effect of carbamide peroxide (CP) bleaching agents of different concentra tion and carrier on enamel roughness. METHODS: Forty -four incisors with 5×3mm flat on medial and distal labial surfaces were randomly assigned to four groups. Carbopol, PVP or Poloxaraer were used as thickening carrier respec tively, and gels containing 0 CP, 100 g/L CP or 200 g/L CP, Opalescence 100 g/L and 200 g/L CP bleaching gels were applied on the enamel specimens for 2 weeks (8h/d, 37℃ ,100% relative humidity). Surface roughness was measured before and after treatment. RESULTS: When Carbopol or PVP was used as the thickening carrier, there was no significant change regarding enamel roughness prior and post treatment with 100 g/L CP( P > 0.05). When Polox amer was used as the thickening carrier, the roughness of enamel was significantly increased after treatment with 100g/LCP(P<0.05). The roughness of enamel treated with 200 g/L CP using different carriers was significantly in creased after bleaching treatment(P<0.05). Except the one treated with CP bleaching gels using Poloxamer as thick ening carrier, there was no significant difference between groups treated with different carriers when the CP concentra tions were the same. There was no significant difference (P>0.05) in enamel roughness treated with gels without CP. CONCLUSION: Thickening carriers have no significant effect on the roughness of enamel surface. 100 g/L CP with Carbopol or PVP as the thickening carrier has no effect on the roughness of enamel surface,but when the CP concentra tion increases to 200 g/L,the roughness of enamel surface significantly increases.100 g/L CP and 200 g/L CP with Poloxamer as the thickening carder greatly increase enamel surface roughness also.