Microscopic aspects of junction between dental hard tissues and composite material depending on composite insertion: layering versus bulk-fill.

Polymerization stresses in adhesive structure could determine an adhesive or cohesive failure and interfacial gaps forming. Some clinical procedures - as light curing composite resin layering in 2-3 mm increments (especially for dental fills) or using dental reconfiguring clear acetate crowns - are sat up to combat (in some way) the polymerization shrinkage. This study approaches the manner how clinical dental adhesive application could influence the hard dental tissues-composite materials interface. The sample studied consisted of 12 upper bicuspids, extracted for orthodontic reasons. In our study, we chose the adhesion technique in "two steps". We prepared enamel and dentine areas, and then filled them with light-polymerization composite. After that, the teeth were subject of microscopic investigations, at 100× and 200× magnification. As conclusion of our study, we sustain that light curing composite resin applying clinical technique (by layering or with acetate crown) might influence a good dental restoration clinical performance.