Static Analysis with a Realistic Loading Condition on All-Ceramic Crown Prosthesis During Chewing

PURPOSE: To evaluate the stress distribution during chewing in a realistic loading condition on a prosthesis (single-tooth crown) using a static analysis. MATERIALS AND METHODS: An all-ceramic crown in the mandibular first molar was selected as the representative prosthesis. First, three contact states (intrusive state, transition state, and extrusive state) were selected from the parametric chewing trajectory. Then, the distances between the antagonistic molars and the normal vectors of the mandibular first molar were calculated by using an automated contact analysis routine (independently developed). Next, normal and tangential forces were defined based on the contact information and the food property. Finally, the static analysis was executed by applying the force and the fixed boundary condition. RESULTS: The distribution of the occlusal force was nonuniform in the static analysis. Compared to concentrated and uniform loading conditions, the stress distribution of the prosthesis under the nonuniform loading condition revealed new characteristics. CONCLUSION: The generation procedure of the static analysis, based on fundamental contact analysis, was evidence-based. The static analysis with the nonuniform loading condition was more recommended than the other two conditions.

Synthesis and pharmacological evaluation of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives as sigma-2 receptor ligands.

Increasing evidences have implicated that sigma-2 receptor is a biomarker and significantly over-expressed in many proliferative cancer cells with no or low expression in normal cells. Sigma-2 receptor selective ligands have been successfully used as valuable tools to study its pharmacological functions, tumor imaging, and cancer therapeutics or adjuvants. 6,7-Dimethoxy-1,2,3,4-tetrahydroisoquinolinylalkyl benzamides are among a few categories of structures that have demonstrated high affinities and selectivities for sigma-2 receptor and been used extensively as study tools in various tumor imaging and therapy. As a continuous effort, we have synthesized a new series of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives and evaluated their affinities for both sigma-1 and sigma-2 receptors. Most of these newly developed analogs showed good to excellent binding affinities for sigma-2 receptor with no or low affinities for sigma-1 receptor. In particular, compounds 3b, 3e, 4b, and 4e demonstrated Ki values of 5-6 nM affinities and excellent selectivities for sigma-2 receptor. In addition, these analogs also demonstrated moderate anticancer activities against human liver Huh-7 tumor cells and human esophagus KYSE-140 cancer cells. But their cytotoxicities seem not to be correlated with their sigma-2 receptor affinities.