ANALYSIS OF STRESS DURING THE PLACEMENT OF REMOVABLE DENTURES OVER IMPLANTS

Abstract

Implant-supported removable dentures are one of prosthetic dentistry modalities to replace missing teeth and have a long history of the development. Dentures placed over implants offer opportunities to restore dentition defects resulted from various causes. Different defects of the dentition require their own restorative techniques. In recent years, implant-supported prostheses have become more commonly preferred over full dentures. For patients with low distal bone levels and problems with placement and stabilization, 4-implantsupported dentures seem to be a good option. Four bar implants for supporting dentures are considered more reliable in terms of fixing the prosthetic structures over them. The aim of this work is to analyze the effect of implant-supported denture placement on the implants themselves and peripheral tissues, depending on the denture models, level of implant placement, the angle of placement, as well as the length of the console in the structure. Results. In 10 different mathematical models, the angles of implant placement in the bone were taken as equal to 90°, 17° and 30°, and the level of placement was equal to 1 mm and 3 mm (in accordance with the configuration of the jaw bone). The length of the cantilever bar system prepared on implants was 0 mm, 5 mm and 10 mm in different models. The load on the model was actually equal to the chewing pressure, 100 N (approximately 10.2 kg), when chewing a 1 cm solid food mass. The pressure was applied from 3 different points: from the anterior section, when the centre of the bolus was at the place of contact between the central incisors; in the right posterior region, when the centre of the bolus was at the contact between the 2nd premolar and the 1st molar; from the left posterior region, when the centre of the bolus was in the area of contact between the 2nd premolar with the 1st molar. After 3D analysis, the Von Mises stress findings in the implant area and the corresponding color scales were obtained, as well as the maximum and minimum stress values in accordance with the color scale. Conclusion. Based on the analysis and comparison of the obtained values, the study has determined that the stress distribution is optimal for some implant models, for others it can be too small or too large due to uneven stress values. The study of models based on the method of 3D three-dimensional stress analysis by the finite element method and the results of these studies are elucidated in the article.