The evaluation of resin infiltration effects on bleached initial caries

Objectives: The aim of this in vitro study was to investigate the effect of resin infiltration on color and microhardness of white spot lesions treated with bleaching and to analysis of the penetration of the infiltrant.
Methods: Enamel specimens were prepared from extracted bovine incisors (n=135). Initial color and surface hardness were measured with spectrophotometer using the CIE L*a*b* system and a Vickers hardness device, respectively. After producing artificial white spot lesions, color and hardness values were re-measured. Then specimens were randomly divided into three groups (n=45): Group I-resin infiltrated (ICON); Group II- bleached (Opelescence Boost, 40% Hydrogen Peroxide); Group III-bleached/resin infiltrated. After subjecting all specimens to pH cyclus for 4 weeks, assessment of color and microhardness were repeated. Color alterations (ΔE*) and the percentage of surface microhardness recovery (SMHR) were calculated.The penetration of infiltrant was evaluated with scanning electron microscope. Data were submitted to one-way ANOVA and Tukey test (5%)
Results: There were no statistically significant differences in ΔE* values between group I and II (p=0.525). Highest color alterations were observed in Group III that was significantly different from GroupI and III (p=1.00). Bleached samples (Group II) showed the lowest SMH recovery (p<0.005). The penetration of resin infiltrant was significantly deeper in Group I.
Conclusions: Application of resin infiltration after bleaching of white spot lesions could influence color alteration positively. Moreover, the microhardness of white spot lesions either bleached or not was increased with resin infiltration. The bleaching treatment infiluenced the penetration of the infiltrants negatively.