CAUSES OF MICRO-LEAKAGE
An article written by Bagis et al. compared micro-leakage between silorane-based resin composite and nanohybrid-based resin composite restorations. The results of the study concluded that the enamel and dentin margins for silorane-based resin composite restorations showed no leakage. The nano-hybrid-based resin composite restorations presented with varying levels of leakage. Applying the findings of this study, a clinician may want to consider use of a silorane-based resin composite to limit micro-leakage experienced by the patient.
A study appearing in Operative Dentistry compared micro-leakage associated with a variety of instrument combinations used for composite placement. Four instrument combinations were assessed; a metal matrix with wooden wedge, a transparent matrix with reflective wedge, a metal matrix with wooden wedge and light tip, and a metal matrix with wooden wedge and bio-glass cylinder. The study found that exclusive use of a metal matrix with a wooden wedge, as compared to a transparent matrix and a reflective wedge, significantly increases marginal leakage. Using a conical tip, or other similar light-conducting instruments, significantly reduces micro-leakage to a level equivalent to that of a transparent matrix and reflective wedge. Applying the findings of this study, a clinician should no longer continue to solely use a metal matrix and wooden wedge.
Intermediary Flow layer
A study published in the Journal of Dentistry assessed cervical enamel micro-leakage with and without an intermediary flowable resin-based composite (RBC) layer for the incremental restoration of mesio-occluso-distal (MOD) cavities. Use of an intermediary flowable resin-based composite layer is based on the “elastic cavity wall concept”, which states that an elastic intermediary layer can absorb stress and thus reduce the shrinkage generated at the tooth-composite border. The results of the study indicate a reduction of micro-leakage at the cervical enamel cavosurface margin, when an intermediate layer of a flowable RBC was used. The findings of this study suggest that operators should consider the use of an intermediary flowable resin-based composite layer in order to reduce micro-leakage.
A study by Schneider et al. contrasted tooth-composite interface morphology and micro-leakage formation using a multi-component, three-step, total-etch adhesive system. The study compared one group of teeth in which Syntac Clasic (Ivoclar Vivadent AG) was applied according to the manufacturers’ instructions to another group in which the Heliobond was applied twice. The double application of the component Heliobond from the Syntac System resulted in partially increased sealing of enamel and dentin and in the partial reduction in adhesive failures along the dentin interface. However, the second Heliobond application did not lead to a lessened formation of micro-leakage.
Cavosurface marginal adaptation ...