OptiBond® Solo Plus™ is a single-component adhesive designed for both direct and indirect bonding applications. It is 15% filled with the same 0.4 micron filler found in the Kerr Point 4 composite. The filler reinforces the hybrid zone and penetrates the dentin tubules, creating a true "structured bond" not found in unfilled or even "nano" filled adhesive systems.This provides protection against microleakage, while sustaining high bond strengths to a variety of surfaces.