Ron Kaminer, DDS
When one mentionsadhesives in dentistry, the first thing that comes to mind is the term generation. Adhesive dentistry has changed dramatically since the early work of Michael Buonocore, DMD, MS.1 As the dentistry has changed or improved, so has the chemistry, the delivery, the mechanics of the technique, as well as the effectiveness of the product. Today, most dentists use the latest generation of adhesives, classified as universal adhesives.
Universal adhesives allow dentists to use the product in a variety of modes—i.e., self-etch, selective-etch, and total-etch—with no difference in outcome. While the pH of these adhesives tends to be on the lower side (2.2–3.4), which is more than sufficient for dentinal bonding, the concern for many lies in the ability to effectively etch and bond to enamel with these products.2 While many continue to use these products in a self-etch mode and have advocated selective-etch for years, this remains the technique of choice.
The selective-etch technique involves etching the enamel with phosphoric acid prior to using the universal adhesive. Newer studies recommend shorter etch times, with some studies touting no benefit after a three-second phosphoric acid etch.3 Most also recommend some alteration to the enamel, as in a bevel, since universal adhesives bond better to cut enamel versus uncut enamel.4 Adhesives should be massaged thoroughly into the tooth surface for optimal penetration into the dentinal tubules.5
Universal adhesives pack a tremendous amount of chemistry into one bottle. The fragility of the monomers comes into question for many in these one-bottle systems, although the stability of the chemistry has improved dramatically throughout the years. When using a one-bottle system, one should be cautious to recap the bottle immediately after use to minimize any potential evaporation of the material from inside the bottle.
One interesting product that I have used for a long time is Futurabond U (Voco), which has a blister pack delivery system to reduce material evaporation. Another feature to note about Futurabond U is the ability to use this material in an indirect fashion. Some universal adhesives need an additional component (dual-cure activator) when used with an indirect restoration. Futurabond U has dual-cure capabilities already built in, which eliminates a step when bonding in a post, cementing a crown, or cementing an onlay.
Case No. 1
This case involved a seemingly routine Class III cavity on a 13-year-old girl, who was terribly apprehensive of the dentist and injections (figure 1). After initial consultation with the patient and her parent, it was decided that we would use the LiteTouch Er:YAG laser (AMD Lasers) instead of a high-speed handpiece for the cavity preparation. This laser can often be used without anesthetic, as its energy is absorbed by water and hydroxyapatite to cut hard tissue in an efficient manner. The laser’s energy will also remove the smear layer, making it ideal for a bonded restoration.6
The completed preparation shows clean margins and complete decay removal (figure 2). Due to the depth of the preparation, a urethane dimethacrylate calcium liner (Calcimol, Voco) was placed and light-cured for 15 seconds (figure 3). The enamel margins were etched for 3 seconds (Vococid, Voco) and the etch was rinsed off (figure 4). A mylar strip and wedge (Composi-Tight 3D Fusion Wedge, Garrison Dental Solutions) were placed and Futurabond U was applied for 20 seconds and massaged throughout the preparation, air-dried, and light-cured (figure 5). Admira Fusion (Voco) shade A2 was placed in two increments and light-cured. The final polished restoration shows ideal esthetics (figure 6).
Figure 1: Preop: Class III cavity on 13-year-old patient
