Revisiting the Microleakage in Tooth-coloured Sandwich Restorations

The placement of glass ionomer cement as lining material below composite fillings was introduced by McLean and Wilson in 1977. This technique incorporated different layers of restorative materials placed onto tooth, similar to layers of a sandwich. It was proposed this technique will provide a molecular seal to dentine in addition to mechanical and aesthetic properties of composite resin. Placement of liner or an intermediate layer underneath the main bulk of restorative materials reduces polymerization shrinkage stress and resultant microleakage of the final restoration. To date, dentine adhesion and polymerization shrinkage are limitations of resin-based restorative materials. At present, wide array of tooth-coloured restorative materials with different formulations is available. Despite advancements in restorative dentistry, no single technique or material is ideal in both clinical effectiveness and simplicity. Clinicians may find themselves in a dilemma when choosing restorative materials and techniques that provide the best clinical results with minimal technique sensitivity or chairside time. The aim of this review is to present existing scientific evidence in microleakage and sandwich technique in restorations, and to discuss multiple approaches in sandwich restorations in effort to reduce microleakage of dental restorations. Clinical recommendations will be given based on evidence from multiple studies.