This research addresses the development of a formalized approach to dental material selection (DMS) in manufacturing removable complete dentures (RDC). Three types of commercially available polymethyl methacrylate (PMMA) grades, processed by an identical Digital Light Processing (DLP) 3D printer, were compared. In this way, a combination of mechanical, tribological, technological, microbiological, and economic factors was assessed. The material indices were calculated to compare dental materials for a set of functional parameters related to feedstock cost. However, this did not solve the problem of simultaneous consideration of all the material indices, including their significance. The developed DMS procedure employs the extended VIKOR method, based on the analysis of interval quantitative estimations, which allowed the carrying out of a fully fledged analysis of alternatives. The proposed approach has the potential to enhance the efficiency of prosthetic treatment by optimizing the DMS procedure, taking into consideration the prosthesis design and its production route.
(1) Background: The paper addresses the computer simulation and prediction of the service life of the base of removable complete dentures (RCDs) under typical loads caused by biting and chewing food. For this purpose, the finite element method (FEM) was used. It is assumed that various blocks of teeth, such as incisors, canines, premolars and molars, are subjected to cyclic impacts during a human life. (2) Methods: Both symmetric and asymmetric mastication (two- and one-sided loads, respectively) cases were considered. The load level was assumed to be 100 N, which corresponds to the average muscular compression force of typical human jaws. (3) Results: The FEM analysis of the stress–strain state evolution for RCDs under cyclic loads was carried out. Maps of equivalent lines were drawn for the denture base in terms of its durability. A multi-axial criterion was implemented to determine the number of cycles prior to failure by the mechanism of a normal opening mode crack. The FEM-based assessment of the service life of RCDs enabled us to establish the critical stress concentration areas, thereby allowing for further planning for the correction of an occlusal scheme or teeth inclinations. As a result, the service life of RCDs under cyclic loading can be improved. (4) Conclusions: An algorithm for designing RCDs in the case of edentulism based on the FEM simulation using commercial software as part of the procedure is proposed.
The modern orthopaedic dentistry offers different constructions for restoration of masticatory efficiency. The choice of construction depends on medical indications with individual patient’s features. Because of that during the dental prosthesis implantation, a doctor faced to the problem of the shape and position parameters choose. Generally, this problem is solved based on empirical guidelines for doctors and personal experience. However, even in the practice of the doctor with a large clinique experience, the prosthesis lifetime does not always reach the guaranteed durability. This paper is focused on the problem of prosthesis base fracture under the natural chewing loads. The mathematical model of prosthesis base interaction with oral tissues is proposed together with 3D finite element simulation of chewing loads. The results of the simulation show a principle distribution of stress in the basis of prosthesis under chewing loads depending on its application. It is outlined an important role of prosthesis base interaction with an anatomic features (torus) of oral cavity. The relation between prosthesis base shape and critical stress state under natural chewing loads is studied.
This paper is focused on the numerical simulations for the mechanical behavior of the prosthesis basis under typical chewing loads. The model is supplied by physically correct boundary conditions. The stress analysis in the prosthesis basis is performed for the cases of symmetric and not-symmetric loading conditions. The sets of numerical calculations were performed for all the stages of food chewing. It was found that not-symmetric loading has a higher influence on the structural integrity of the prosthesis. The significant stress amplitudes on the basis were found under the loading at the block I (incisors) and block II (fang). It is shown that the maximum stress due to typical chewing loading usually cannot produce the prosthesis fracture in one cycle. However, the stress level is high enough to produce the fatigue crack initiation.
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