An in vitro study of the wear behaviour of dental composites

Use of dental resin composites in restorative dentistry has increased significantly in recent years. While wear may be of minimal importance for small to medium size composite restorations, failure rates are higher for large restorations. Moreover, wear is a significant mode of posterior restoration failure for patients with bruxing and clinching habits. However, in spite of previous in vitro studies, the mechanisms associated with the wear of these composites are not yet clearly identified. Accordingly, the wear behaviours of three different glass-polymer dental composite materials were studied in vitro and the associated mechanism(s) were investigated in-depth.Reciprocating sliding wear tests were carried out using these composites where a self-mating composite cusp was sliding on a flat-surface sample. The wear loss was quantified using profilometry and the wear scar surface and subsurface were analysed using electron microscopy techniques to reveal the underlying wear mechanisms. The composites' mechanical properties were assessed using nanoindentation.The results revealed that two different wear mechanisms were dominant for the composites tested: fatigue wear for the anterior/posterior composites and, abrasion due to lateral crack formation and filler particle pull out for the anterior composite.