Effect of dentin pretreatment with potassium oxalate: A 6-year follow-up.

Oxalate-based products are effective against dentine sensitivity and have been studied as an option to improve long-term adhesive bonding strength. Our aim was to evaluate the effect of potassium oxalate on the microtensile bond strength (µTBS) of the dentin/resin interface after 24 h, 1, and 6 years. Dentin on the occlusal surface of 16 human premolars was exposed and etched with 35% phosphoric acid. The teeth were divided into four groups. Two groups received 3% monohydrated potassium oxalate and the following adhesive systems and composites: Adper Scotchbond Multipurpose + FiltekZ350 (3M/ESPE) and Prime & Bond NT + Esthet-X (Dentsply). Two control groups did not receive potassium oxalate. Teeth were cut into sticks and kept in distilled water at 37°C for 24 h, 1, and 6 years. The sticks underwent µTBS testing after storage. ANOVA, Tukey's post hoc test, and paired t test were used to compare storage times (α = 0.05). The fracture mode of the specimens was classified under a stereomicroscope (40×). Morphology of the hybrid layer and the fracture pattern were observed with scanning electronic microscopy (SEM). Mean µTBS was high at 24 h and decreased after 1 and 6 years. After 6 years, the mean µTBS values were similar with no statistically significant difference between the groups (p = .121). SEM images showed proper dentin hybridization. Dentin pretreatment with potassium oxalate did not affect hybrid layer formation, but bond strength decreased over time after 24 h. Therefore, the clinical use of potassium oxalate to increase dentin bond durability is not indicated.