2024 年 15 巻 1 号 p. 8-18
The main causes of failure in core build-up are loss of dowel, root fracture, and coronal leakage. Because conventional methods are limited in how they can combat them, fiber-reinforced resin core build-up is currently the first-choice method, and achieving a supragingival tooth structure, fiber arrangement, and adhesion to the root canal dentin are considered to be important for improving its predictability.
One role played by the supragingival tooth structure is supporting occlusal force, and since its size is the most important factor in improving the fracture resistance of the abutment tooth, orthodontic extrusion and crown lengthening should be actively used to achieve this. Fibers provide effective reinforcement as long as they are positioned at sites subject to tensile stress, and they are most effectively positioned horizontally so that they surround the outermost circumference of the abutment cavity, and vertically so as to straddle the gingival margin line, which is where horizontal fractures are most likely to occur. Before setting the post and core, any remaining plaque, temporary filling, or other material that could prevent adhesion must be thoroughly removed from inside the abutment cavity and from the surface of the post and core, and appropriate pre-adhesion treatment of both surfaces is required. Self-contained chemically cured resin cement (Super-Bond) is suitable for use as adhesive resin cement. If secure adhesion to the dentin can be achieved, whether the direct or indirect method is used is immaterial, but if control of the progress of the adhesion reaction is an aim, then the indirect method is more reliable.
