The objective of this study was to investigate the stress distributions of a surface-treated dental implant and bone tissue under physiological loading. For ensuring success of dental implant treatment, one must examine the magnitude and location of the maximum stresses. Stress analysis models were constructed from computer tomography data. Although several studies have investigated finite element models of dental implants, none have used an implant model with a nanoporous layer in a biomimetic geometrical mandible model. The novel implant surface used in this study, comprised of a microlevel porous containing a nanolevel porous structure, was complex and it was difficult to present due to the limitation of computer efficiency. However, this complex geometry was simplified using a film, to further investigate stresses resulting from 0 nm, 50 nm, 500 nm, 5 μm, and 50 μm surface treatment thicknesses. Results indicated that the stresses transferred more uniformly in implants with nanoporous surface treatments, and that the stresses decreased with increasing layer thickness. Our study showed that this could be potentially beneficial for understanding the stress properties of surface-treated layers for dental implants.

Decision tree analysis and logistic regression suggest that the leading contributors to the formation of the membranous substances were the method of ingesting nutrients, dryness of the tongue dorsum and open mouth. These three factors are related to elderly persons requiring nursing care with impaired oral cavity function, and it was suggested that dryness of the oral mucosa was the major factor behind the membrane formation.