By Lee Ann Brady, DMD

Sorting through the myriad of dentin bonding systems and products on the market can be time consuming. During the course of a busy day in the office, using a highly efficient system, which is not time intensive, is a very attractive option. When bonded restorations fail prematurely, it affects both the practice's bottom line and the experience of practicing dentistry, so excellent bond strengths and low technique sensitivity are also important. This is exactly why there are so many different systems and so much money is invested in the development of bonding systems — to try to maximize efficiency, bond strength, and ease of technique all in one product.

Dentin bonding systems can be divided into two broad categories: systems that begin with a total etch and those that are self-etching.

One group of total etch dentin bonding systems utilizes two bottles — primer and then resin. The first step is the application of etchant. Begin by running a ribbon along the enamel, and then coating the cut dentin surfaces. In this way, you etch the dentin for no more than 15 seconds and achieve a longer etch time of 20 to 25 seconds for the enamel surfaces. Rinse the etchant thoroughly; then dry the areas around the tooth and leave the prep moist. Determining the appropriate amount of remaining moisture can be challenging and overcome by the application of a rewetting agent. The next step is application of the primer, which is then dried to volatilize the solvent. The final step is application of the resin.

The total etch two-bottle systems have consistently shown excellent bond strengths and are compatible with a wide variety of composite restorative materials and resin cement systems. The number of steps requires additional time and can introduce more opportunities for technique error.

There are also total etch dentin bonding systems where the primer and resin have been combined in one bottle. The tooth is etched in the same manner as the two-bottle systems. Monitoring the time that the dentin is exposed to etchant is a critical factor as over-etching has been implicated in postoperative sensitivity. The etchant is rinsed and the excess moisture removed while maintaining adequate moisture on the dentin. Over-drying the dentin causes the dentin tubules to collapse and can result in postoperative sensitivity and decreased bond strength. The primer and resin are applied together in one step, and it is important to adequately coat the walls of the prep. Applying multiple layers or agitating the product for a minimum of 15 seconds can help assure adequate coverage.

These systems have shown good to excellent bond strengths and have the advantage of one less step than the two-bottle systems. These products are not universally compatible with all composite and resin bonding systems.

The next broad category includes the systems that are self-etching. The advantage of self-etching systems is elimination of the risk of over-etching and, therefore, a decreased risk of postoperative sensitivity. Self-etching systems come in either a two-bottle or single-bottle variety. The two-bottle systems combine the etchant and the primer in the first step. These systems have shown good to excellent bond strengths to nonsclerotic dentin, but have lower bond strengths to enamel and sclerotic dentin. Single-bottle systems have combined all three pieces of the process — etchant, primer, and resin — into one application.

These systems have become popular because of the low incidence of postoperative sensitivity and fewer clinical steps, which save time and leave less room for error. The compromise is reduced bond strengths when compared with the other systems.

The final factor to consider when comparing these products is their compatibility with composites and resin cements, and their application during a light-cured or dual-cured process. Each of the systems has inherent advantages and disadvantages. Choosing a technique and specific product is about understanding the clinical application, the other resin systems involved, and your own practice systems and goals.

Dr. Lee Ann Brady earned her DMD degree from the University of Florida College of Dentistry. She practiced in several private restorative practice models for 17 years before leaving to devote her time to teaching. While in private practice, Dr. Brady taught part time at the Santa Fe Community College dental hygiene program. In January 2005, she joined the Pankey Institute as a full-time faculty member, and became clinical director in 2006. Dr. Brady joined the Spear Institute as vice president of clinical education in September 2008. In addition to her teaching responsibilities, she maintains a limited clinical practice focused on comprehensive restorative care. Dr. Brady is a member of the American Dental Association, American Equilibration Society, Academy of General Dentistry, American Academy of Cosmetic Dentistry, American Academy of Fixed Prosthodontics, American Association of Women Dentists, and is a fellow in the American College of Dentists. Dr. Brady has been published in numerous publications including Woman Dentist Journal, AAWD Chronicle, Dental Practice Report, Spectrum, Journal of Dental Technology, ADA News, Private Practice, and Dentistry Today. You may contact Dr. Brady by e-mail at lbrady@scottsdalecenter.com.