Development of methodologies for the assessment of oral prostheses.

D'Arcy, Susan

Abstract

Besides medical and physiological consideration, the integrity of endodontic post/crown restorations are largely influenced by the components of the system adopted, namely the post, core material and cement. Currently there are numerous forms of posts, cements and core materials available on the market. Research relating to endodontic posts and cements has primarily concentrated on the retention of the post within the endodontic canal and has frequently excluded the other components within the system. Testing has also been extremely basic, deploying techniques such as simple pull tests, compression testing and photoelastic analyses and has overlooked the effect of bending and torsion on the restoration. In order for future research to become more meaningful, there exists the need for experimental methodologies and protocols which will; investigate combinations of post, core and cement systems and not the individual components; investigate the performance of these systems to applied loading in direct shear, torsion and bending which to date has not been incorporated in testing; investigate the use of real posts, cores and cements in an environment more representative of that experienced in the mouth; accommodate multiple tests under identical conditions which arc required for professionally accepted standards. An extensive literature review confirmed that there was no published work which has incorporated the above points. This research has resulted in the development of a methodology based around fatigue of multiple samples in a humidity and temperature representative of the working environment of the restorative system. Appraisal of the system was then achieved using microleakage examination. The material used as a substitute for dentine was beechwood which has mechanical and granular properties similar to dentine. The mode of fatigue loading has been combined direct shear, torsion and bending. Finite clement techniques have been deployed and used qualitatively to gain an appreciation of the interaction of the post with the substrate material, in particular to identify areas of high displacement/stress at the interface of the tooth (represented by beechwood) and restorative system. Finite element analysis was also used to identify areas of high displacement in the system used for cyclic load testing. The use of Holographic Interferometry to assess the displacement levels was also investigated, but due to the limitations of the technique did not give any substantial additional support of the findings, however a description of the technique and results is included. The use of cyclic load testing has resulted in the development of a method which is capable of identifying changes in the behaviour of cements, at the core/crown interface of a post/crown restoration, when subjected to direct torsion shear and bending. A finite element model has been developed, and verified, to identify the areas of high stress concentration in a post/core/crown restoration.

Citation

D'ARCY, S. 1998. Development of methodologies for the assessment of oral prostheses. Robert Gordon University, PhD thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2807353

• Thesis Type: Thesis
• Deposit Date: Aug 13, 2025
• Publicly Available Date: Aug 13, 2025
• DOI: https://doi.org/10.48526/rgu-wt-2807353
• Public URL: https://rgu-repository.worktribe.com/output/2807353
• Award Date: Dec 31, 1998