A survey of failed post-retained restorations

Survival of endodontically treated, post-restored teeth depends on a multitude of factors, all of which are practically impossible to include in a randomized, controlled clinical study. The purpose of this survey was to characterize and analyze reported failures of post-retained restorations to identify factors critical to failure and to type of failure. A questionnaire was mailed to private practitioners in Denmark with a request to complete the questionnaire whenever a patient presented with a failed post-retained restoration. Information was gathered on factors related to the patient, the tooth, the restorative materials, and the techniques. Two-hundred and sixty questionnaires were collected from 171 practitioners over a 3-year period. Functioning time until failure varied between 3 months and 38 years. Mean survival time until failure was 11 years. Of the failed restorations, 61% had functioned for 10 years or less. Fracture of the tooth was the most common type of failure reported, followed by loosening of the post and fracture of the post. Tapered posts implied an increased risk of tooth fracture compared to loosening or fracture of the post, and the relative risk of tooth fracture increased with the functioning time until failure. Fracture of the post was more common among male than female patients. On the basis of this survey of failed post-retained restorations, it was concluded that tapered posts were associated with a higher risk of tooth fracture than were parallel-sided posts

Fiber-reinforced dental composites in beam testing

OBJECTIVES: The purpose of this study was to systematically review current literature on in vitro tests of fiber-reinforced composite (FRC) beams, with regard to studies that followed criteria described in an International Standard. The reported reinforcing effects of various fibers on the flexural strength and elastic modulus of composite resin beams were analyzed. SOURCES: Original, peer reviewed papers, selected using Medline from 1950 to 2007, on in vitro testing of FRC beams in comparison to non-reinforced composite beams. Also information from conference abstracts (IADR) was included. DATA: With the keywords (fiber or fibre) and (resin or composite) and (fixed partial denture or FPD), the literature search revealed 1427 titles. Using this strategy a broad view of the clinical and non-clinical literature on fiber-reinforced FPDs was obtained. Restricting to three-point bending tests, 7 articles and 1 abstract (out of 126) were included. Finally, the data of 363 composite beams were analyzed. The differences in mean flexural strength and/or modulus between reinforced and unreinforced beams were set out in a forest plot. Meta-regression analyses were performed (single and multiple regression models). CONCLUSIONS: Under specific conditions we have been able to show that fibers do reinforce resin composite beams. The flexural modulus not always seems to increase with polyethylene-reinforcement, even when fibers are located at the tensile side. Besides, fiber architecture (woven vs. unidirectional) seems to be more important than the type of fiber for flexural strength and flexural modulus