Comparative evaluation of structural changes in acid etched primary enamel pretreated by 5.25 % sodium hypochlorite gel and solution – an sem study

Background: Resin based composite materials are widely used for aesthetically restoring primary teeth. Fundamental mechanism for resin - enamel adhesion relies on resin - micro tag formation. This is achieved by acid etching, where the smooth enamel surface is transformed into an irregular surface with increased surface energy. Primary enamel has increased organic content than permanent teeth which stand as a barrier in the way for achieving generalised retentive surface over the entire acid treated surface. Deproteinization of enamel is proposed as a non- invasive way by which organic protein content of enamel can be removed. 5.25 % sodium hypochlorite has been used as an endodontic irrigant due to excellent protein denaturing action, which might also be effective in removing organic content of primary enamel structure. Objectives: To evaluate and compare the effect of sodium hypochlorite conditioning on the surface micro morphological features of acid etched primary enamel. Methods: Buccal enamel surface of 10 extracted human primary molars were cut and into trimmed to forty 2 mm2 blocks. Each group comprises of 10 enamel blocks (1mm2 size). Group 1: No treatment group Group 2: Enamel surface etched with 37 % H3PO4 for 15 sec, washed and dried for 10sec Group 3: Enamel surface pre-treated with 5.25% NaOCl solution for 120 seconds, washed, dried and etched as for Group1. Group 4: Enamel surface pre-treated with 5.25% NaOCl gel for 120 seconds, washed, dried and etched as for Group1. Samples subjected to SEM analysis and 5 microphotograhs of each sample were obtained at 500x magnification and evaluated for quality of etching pattern of enamel in percentage using Auto –CAD 2014 software. Statistical analysis used: Anova Result: The mean value of acid etching pattern was similar between Group 2 and Group 3( p = 0.78), but the mean value of acid etching was significantly lower in the Group 4 (p=0.04) than in the control group. Conclusion: Acid etching with 37% phosphoric acid for 15 seconds still remains the best method of pretreatment in primary enamel. There is no significant effect of deproteinization with 5.25% NaOCl on acid etched enamel surface.