Time-lapse submicrometer particle motion reveals residual strain evolution and damaging stress relaxation in clinical resin composites sealing human root canals

The restoration of endodontically treated teeth is a topic that is extensively studied and yet remains controversial from many perspectives. This article reviews the major pertinent literature on this topic, with an emphasis on major decision-making elements in post placement and restoration of endodontically treated teeth. Recommendations are made for treatment planning, materials, and clinical practices from restorative and endodontic perspectives.

The setting stress in composite resins was studied as a function of restoration shape. The shape is described by the configuration factor, C, the ratio of the restoration's bonded to unbonded (free) surfaces. In an experimental set-up, the shape of the restoration was simulated by cylindrical forms of various dimensions. The shrinkage stress was measured continuously. It was shown that in most of the clinically relevant cavity configurations, the stress-relieving flow is not sufficient to preserve adhesion to dentin by dentin-bonding agents.