The correct answer is e. Glass Ionomer / Microfill Composite Resin
The common theory accepted for the causative agent of abfraction lesion is of an occlusion orgin. Excessive flexion of the tooth causes compression and relaxation at below the CEJ which forces a fluid exchange to occur. This exchange of fluid also carries with it elements of the tooth structure matrix.
In restoring these types of lesions one must take into account several factors. The majority of the margins will exist on dentin/cementum. Enamel may only be present at the occlusal margin. The material chosen should be able to withstand the flexion forces experienced by the tooth, lesion’s position in the esthetic zone, and patient’s caries risk status.
It is accepted that Glass ionomers have the more favorable, low flexural strength and low modulus of elasticity to withstand these forces. As well, they have a chemical bond to tooth structure, and a coefficient of thermal expansion close to that of natural tooth structure. But their wear resistance is low and esthetics fair. For these reasons this restorative procedure would call for a Sandwich Technique where the prep is restored with a GI on all dentin margins, then a veneer of Resin on the enamel margins to esthetically cover some of the GI leaving the GI/dentin margins exposed.
-Amalgam would not serve the esthetic needs and has a very high modulus of elasticity.
-Hybrid Composite is esthetic but flexural strength is high and no true chemical bond to tooth structure, only micro-mechanical can be made to tooth structure.
-Compomers are an option because they are a blend between a GI and Resin. You get a bit of the chemical dentin bond, better wear resistance, some fluoride release, and a bit more flexion.
-Glass Ionomer alone has the bond and flex needed and also supplies optimum fluoride release if it is needed, great bond to dentin, flexural strength and thermal expansion similar to tooth structure, but poorer esthetics an low wear restsiance.
Craig, R.G and Powers, J.M., Restorative Dental Materials 11th Edition, Mosby 2002, page 214-217, 244, 599, 627
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