Rosemary: A Potential Herb To Improve Deleterious Effects Of Bleaching

Bleaching cause complex oxidation reactions that reduce the bond strength of composite resin to bleached tooth structures. Sodium ascorbate, the gold standard antioxidant applied to overcome this, suffers from shortcomings (1, 2). This study aimed to evaluate the neutralizing effect of 10% rosemary ethanolic extract on the bond strength of orthodontic brackets to bleached enamel. This study aimed to evaluate the neutralizing effect of 10% rosemary ethanolic extract on the bond strength of orthodontic brackets to bleached enamel. Rosemary ethanolic extract was prepared using the “cold maceration” technique and chemically characterized. Human upper premolars were collected and divided into four groups: G1: unbleached, G2: bleached (30% H₂O₂ gel), G3: bleached followed by sodium ascorbate, and G4: bleached followed by rosemary extract. Resin penetration into the enamel was observed using scanning electron microscopy. Orthodontic brackets were bonded immediately, and shear bond strength test was performed after 24 hours (n=8/group). The debonded enamel surfaces were observed using a stereomicroscope, and the Adhesive Remnant Index (ARI) was calculated. Results were statistically significant at p ≥ 5. Thicker, more uniform resin tags were observed in G3 and G4 versus G2. G2 has the lowest bond strength in all groups. G4 revealed a significant increase in the shear bond strength compared to G2 and G3, yet G1 was still higher. ARI scores varied among the groups following debonding. Rosemary extract may provide a promising natural alternative to sodium ascorbate although it did not fully neutralize the deleterious effects of bleaching on bond strength.