Today's Adhesive Dentistry
Adhesion and bonding have become the center of research and development in restorative dentistry. Adhesive dentistry concepts and materials have moved dentistry away from obsolete “extension-for-prevention” clinical protocols and literally transformed our profession towards minimally invasive, highly esthetic, and long-lasting dental restorations. Early developments focused on reliable adhesion of direct composite resin materials to dentin and enamel. Traditional etch-and-rinse, multi-step bonding agents were largely replaced by self-etch adhesives, especially when bonding direct composite resins to dentin. For indirect restorations, such as laminate veneers, which are preferably bonded to enamel, etch-and-rinse bonding agents that include acid etching of enamel surfaces with phosphoric acid are still recommended.
Some recently developed products include dual-polymerizing agents that are added and mixed with the self-etch bonding agent. They include initiators that turn the light-cure bonding agent into a dual-cure product. Since they also limit film thickness, these modified self-etch adhesives can also be used for indirect restorations. Such developments make the user-friendly self-etch adhesives much more versatile and expand their indication range to indirect restorations.
The variety of materials used for indirect bonded restorations today creates even greater challenges. These materials range from indirect composites to polymers and silica-based and high-strength ceramics, as well as novel material groups such as nano and hybrid ceramics. Each requires different pretreatment protocols and priming agents to achieve long-term durable micromechanical and chemical bonds. These can be quite confusing for practitioners and experts alike. Manufacturers are, therefore, keen on developing bonding agents that not only require fewer treatment steps, but can also be universally applied to dentin and enamel as well as various restorative materials.
The same is true for the increasingly popular self-adhesive resin cements. Versatility is key for this group of novel cements, which is not a small task given the vast differences in restorative material properties and the specific bonding needs for dentin and enamel tooth structures. In addition, bioceramic cements are a new option that offers a universal solution for cementation procedures.
Current adhesive bonding protocols are applied for direct composite resins, laminate veneers, tooth-colored inlays and onlays, bonded ceramic crowns, and resin-bonded fixed-partial dentures. In addition, adhesive treatment concepts impact almost all other dental specialities. For example, we bond endodontic posts into root canals, orthodontic brackets to teeth, crowns onto implant abutments, and composite veneering materials to metal, polymer, and ceramic frameworks.
For all the above reasons, developments in adhesion and bonding are happening at an incredibly fast pace with new products constantly reaching the market. These developments are geared towards user-friendly materials that can be universally applied to tooth structures and the diverse restorative materials available today. They should provide strong and long-term durable bond strengths to assist our profession with its ultimate goal: to provide our patients with the best possible and most ethical dental care and help them to keep their natural teeth as long as possible.
About the author
Markus B. Blatz, DMD, PhD
Professor of Restorative Dentistry
Chair, Department of Preventive and Restorative Sciences
PENN Dental Medicine