Duraflor Ultra 5% Sodium Fluoride White Varnish – STRAWBERRY, 0.4 mL Unit Dose 30/Bx. Sweetened with Xylitol. Ultra varnish is easy to apply and dries to a natural tooth color. Advanced formula quickly releases fluoride within 2-4 hrs, so your patients get the maximum fluoride benefit while the varnish is still on their teeth.