Effect of various chemical agents used in gingival retraction systems on smear layer: Scanning electron microscope study

BACKGROUND: Chemical agents used for gingival retraction affects the smear layer. AIM: To determine the effect of three different chemical agents used for gingival retraction systems on smear layer. MATERIALS AND METHODS: Four human premolars were prepared using air-rotor with air-water spray to receive full crown restoration. Three of them were treated with 21.3% aluminum chloride for 10 min, 0.05% oxymetazoline hydrochloride for 10 min, and expasyl for 2 min, respectively. One sample was left untreated. Then, the tooth specimens were rinsed with tap water to remove any residue of test materials. All the samples (treated and untreated) were processed by scanning electron microscope (SEM). Processed samples were examined under SEM at ×2400 to evaluate the effect of chemical agents on smear layer. RESULTS: SEM examination revealed that 0.05% oxymetazoline hydrochloride for 10 min produced no alteration to smear layer followed by minimum alteration by expasyl for 2 min and complete removal of smear layer with etching of dentin with 21.3% aluminum chloride for 10 min. CONCLUSION: 0.05% oxymetazoline hydrochloride and expasyl are kind to smear layer.