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July 2009 | Dental Products Report
Clinical 360°: Cosmetic/restorative

The take-aways

Results speak for themselves

A one-year follow-up on the “Noah Technique” and how it demonstrates predictable cementation using self-etching resin cements.

by Dr. Robert A. Lowe

The set-up

“Self-etching resin cements are a category gaining popularity as indicated by rising sales over the past year. While there has been some controversy surrounding bond strength and overall efficacy of these cements when compared with more traditional total-etch resin counterparts, remember that no cement can be successful if the preparation is non-retentive. This article looks at a cementation technique using self-etching resin cement and discusses the clinical success of the case one year following placement.”—Dr. Robert Lowe, Team Lead

The resin cement family evolved out of total etch and dentin adhesive technologies. For proper use, they require pretreatment of the tooth surface with 37% phosphoric acid and application of a dentin bonding agent before application of the resin cement.

These cements truly form a micromechanical bond to both tooth structure on one side and restorative material on the other side. Also, they are insoluble in oral fluids.

There are two types of these “traditional resin cements” (those that require the use of the total-etch technique and dentin adhesive technology) that are commonly used—dual cure and light cure. The most recent additions to the “resin cement family” are the self-etching resin cements that require no pretreatment of the tooth surface. They appear to have many of the clinical advantages of traditional resin cement systems, and are as easy to use as more traditional types of cements.

More recent generations of self-etching resin cements, such as Maxcem Elite™ (kerrdental.com), are showing significant increases in bond strength. The manufacturer reports up to 24 megapascals of bond strength, and this is without pretreating the tooth surface. However, it is important to remember the purpose of any cement is to fill the microgap between tooth structure and restorative material, and to aid in retention of the restoration. Proper resistance and retention form of the preparation are still more important for successful retention of any restorative material.

The “Noah Technique”
As I explained when first covering this technique in April of 2008, for any multiple-unit case using a self-etching resin cement that involves the maxillary anterior region, the maxillary central incisors are regarded as most important esthetically. These are the “main actors” on the stage—the first teeth the patient sees. Therefore, the maxillary central incisors should be cemented first.

Delivery of the maxillary definitive restorations
The first step is to place the maxillary central incisors in position and verify seating visually and then radiographically (Fig. 1). Digital x-ray, such as DEXIS, allows immediate verification of complete seating on the operatory monitor.

First, the preparations are cleaned and disinfected with Global Dental Products’ Tubulicid Red (gdpdental.com) on a cotton pellet. Next, the Maxcem Elite self-etching resin cement is placed via automix syringe delivery into the restoration. Once both centrals are completely seated with positive pressure expressing excess around the periphery of the margins, a #2 Keystone brush (pattersondental.com) is used to wipe away all excess material.

Refer to slideshow for figures

The adjacent restorations, the lateral incisors, are placed on their respective preparations to “hold the space” while ensuring the central incisors are properly positioned spatially during the gel state of the cement. One must be sure no cement is on the lateral incisor preparations or the restorations may not be able to be removed after the central incisors are completely set (Figs. 2 and 3). This process is then repeated for the lateral incisors and so on.

If the tissue at any time is unintentionally irritated and starts to bleed, Kerr’s Expasyl (kerrdental.com) is syringed into the area, tapped to place with a dry cotton pellet and left undisturbed for about a minute (Fig. 4). After that period of time, air and water is sprayed to remove the Expasyl, and as a result, the tissue is now displaced away from the restorative margin and the bleeding is stopped.

Invariably, when placing the final pair of restorations, even though there was a previously passive fit, these restorations will now probably be tight and not go to full seat. Proximal contacts should be marked with articulation paper on the master model, as previously described, then adjusted and checked with dental floss in the patient’s mouth. When the restoration(s) has a passive, full seat, it is cemented with Maxcem Elite self-etching resin cement (Figs. 5 and 6).

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