Assessment of the stress–strain state of pin structures and crowns of teeth used to restore the lost crown part of a tooth in a decompensated form of pathological abrasion

BACKGROUND: Restoration of the height of the crown part of the tooth in the decompensated form of pathological abrasion includes measures for reconstructing the general aesthetic appearance, restoring functional components, and correcting temporomandibular joint manifestations. However, even high-quality crowns are not always able to meet the needs of patients while in use. Deformation of orthopedic structures is common, and fractures of the roots used as support for the orthopedic structure are often possible. To prevent negative consequences in the manufacture of orthopedic structures for dentures, specialists who manufacture these prostheses must be familiar with not only the anatomical and topographic features of the teeth’s roots, the state of the alveolar process of the upper and alveolar parts of the lower jaw, the mobility of the mucous membrane, the correctness of determining the central ratio of the jaws, determining the correct position when modeling teeth, and taking into account the functional features of the dentoalveolar system but also the technical, technological, microbiological, and precision characteristics and parametric data of future artificial crowns fixed in the oral cavity. The use of reverse engineering methods allows the traditional technique of manufacturing dentures to be transferred into the digital technology framework and to create a biomechanically sound individual orthopedic design using software and hardware tools, such as CAD/CAM, Exocad, and Ansys. The application of mathematical modeling allows for a more in-depth analysis and, in some cases, the acquisition of strictly individual information about the studied prosthetic structure and the process of its interaction with human biological tissues. All of this will allow orthopedic structures to be built as close to the dentoalveolar system as possible, increasing the period of operation. This paper presents a study of the stress–strain state (SSS) of tooth roots, stump pins, and jaws. Various suprastructure design variants and various materials of stump pins are investigated. A comparative analysis of SSS for various materials of pins and crowns was performed.

AIM: To optimize the design of crowns and pin structures to reduce the load on the remaining roots of the teeth and the surrounding bone structures of the alveolar process’ crest.

MATERIALS AND METHODS: A comparative analysis of the SSS of the jaw with three variants of suprastructures was performed. Option 1: separate single suprastructures, where each is fixed to the root of the tooth. Option 2: a suprastructure combined into a single block by groups of teeth (premolar–molar segments from canine to canine). Option 3: a suprastructure combined into a single block as a “horseshoe.”

RESULTS: For each option, SSS were obtained for various materials of the stump pin inlays.

CONCLUSION: The developed methodology and calculation program enabled three sets of calculations for three options for constructing suprastructures with step displacement along the jaw and a comparative analysis of their SSS.