Deformation measurements of periodontal tissues under dental occlusal forces

Until today, the amount of the local displacement, the data of the local deformation or the loading data obtained from the load cell was only available partially due to the limitation of testing machine and generally used to analyze the displacement and deformation behavior of the periodontal tissues under occlusion forces to investigate the overall behavior of the whole periodontal tissues. Even in some study where the measurements were attempted with using direct imaging techniques, dried periodontal tissues or the photoelastic materials including resins were used. Accordingly their results are assumed to possibly differ from the actual behavior of the in vivo periodontal tissues. In this study, we used a porcine skull obtained from those slaughtered for human consumption to visualize the displacement and deformation behavior of in vivo periodontal tissues under occlusal forces. The prepared specimens were placed on the testing machine, loaded so as to simulate the occlusion pattern by forcing to be deformed and analyzed. Besides the analysis under the occlusal forces, their recovery after unloading, which corresponds to the displacement behavior of the periodontal tissues during the recovery from the occlusal stress was also investigated. In addition, the same test was conducted with using the same but fully dried specimen to reveal the difference in the displacement and deformed behavior between in vivo and dried periodontal tissues. The digital image correlation method was used to visualize the displacement and deformation behavior.