Kerr OptiBond  FL Primer Bottle #1 Refill 8 ml. OptiBond FL^® is a filled, light-cure total-etch dental adhesive that offers a simple two-bottle or unidose delivery with only one light-curing step.This two-bottle primer/adhesive is perfect for all direct restorations and for indirect core build-up. Yet, it's as simple as it is reliable, with a one-coat primer and a one-coat adhesive that can be applied on wet or dry surfaces, with superior dental bonding that virtually eliminates postoperative sensitivity.