Dental Material Placement - Intra Oral Observations

Recent trends in dentistry utilizing magnification and improved intra-oral lighting are leading the way to better dentistry. When this trend started, it was common to hear how much better the tooth and soft tissue condition could be observed, as well as how much more in control clinicians felt. This led to micro dentistry and minimally invasive techniques aimed at reducing the amount of healthy tooth structure removed. These techniques have also been applied to pathological conditions improving early diagnosis of potentially harmful tissue lesions.

In the area of dental materials, more accurate placement of materials, using finer brushes, better selection of applicator tips, and careful removal of material flash before curing polymerizable materials has occurred. This focus should improve margins and provide improved gingival health. As part of the greater accuracy achieved in material placement, we should also see a reduction in placement of materials where they do not belong.

A research report to be presented at this years IADR Meeting in San Diego (1), I think emphasizes in clear results the impact of what should be accepted as good placement technique. This study looked at the placement of different material combinations, such as bonding agents with composites, and evaluated their combined contribution to leakage of a restoration. The study demonstrates the need for more careful placement of dental materials clinically for their intended purpose and location.

Common dental materials such as bonding agents, composites, glass ionomers, and self adhesive composites have very different responses to water uptake and leakage. Material responses mimic what has already been shown for products that contain solvents and/or water (now include glass ionomers or resin modified glass ionomers in this group). Fluid transport through the material can occur more rapidly due to this general compositional aspect. This is in contrast to some self adhesive materials (primarily those that are resin based - ie no glass ionomer or solvent within them, including water). A few examples from this study are shown below.

I encourage those of you using loupes in your practice to further document these observations clinically and to utilize careful material placement whenever possible. The take home message from this study is that dentin bonding agents do not belong on exposed enamel margins.

Figure 1.

Bonding agent with composite restoration showing massive leakage around the edge of the composite/bonding agent interface. Note the interior of composite itself is non-stained (white), this is can be viewed as the center top surface.

Figure 2

Glass ionomer with bonding agent. Note in this example the entire treatment area has turned blue, as opposed to Figure 1, in which leakage has occurred around the edges of the composite/bonding agent interface. In this example, leakage has occurred at the glass ionomer/tooth interface AND through the glass ionomer material itself.

Figure 3.
Self adhesive material, AURA Veneer, showing no leakage at the treatment area. The veneer cement treatment area is the white circular area at the bottom center surface. Note: some leakage occurring around the edge of the tooth - non treatment area. Also note that no bonding agent was used.

Please see the IADR presentation, the Abstract in the Journal of Dental Research, or contact me for further details of their study.

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1. "Contribution of different materials to the leakage of restorations", J.O. Stannard, I. F. Stannard, and S. R. Stannard, J. Dent. Res., Special Issue, 89th Annual Meeting, San Diego, CA (March, 2011).