Fracture resistance of roots with thin walls restored using an intermediate resin composite layer placed between the dentine and a cast metal post.

Thin-walled roots restored using conventional cast metal post-cores are at risk of fracture. Placing a thick intermediate layer of resin-based composite (RBC), sandwiched between the root dentine and a small-diameter metal post or dowel, may improve the fracture resistance of such roots. In this initial laboratory study, two similar groups each of six decoronated maxillary central incisor teeth were prepared with approximately 1.0 mm thick tapered root canal walls. Cast metal alloy post-cores and metal-ceramic crowns were fabricated and cemented for one group with, and for the other control group without, a thick intermediate layer of RBC. The mean force (N) to fracture the roots was 639.3 (SD 51.6) for the intermediate layer of RBC group and 360.8 (42.9) for the control group, P < 0.0001. These significantly different findings require clinical confirmation.