Stress-deformed state of a non-removable prosthesis on implants in the process of cementing, depending on the angle of the abutment walls

Abstract

Despite the widespread use of implant-supported fixed dentures, a number of issues related to their manufacture remain debatable. Many authors raise the question of the necessary degree of inclination of the abutment walls to improve the passive fit and stability of the prosthesis, which determined the relevance and aim of this publication. >. A study of the stress-strain state of the components of a fixed prosthesis during cementation on an abutment (ceramic veneer, frame, cement, abutment) was carried out using the finite element method, depending on the design of the fixed prosthesis, the height and angle of inclination of the abutment walls. A total of 99 models were studied and analyzed. >. The analysis of the obtained results showed that during cementation there are residual stresses in the components of the structure of a fixed prosthesis (metal-ceramic crown). Thus, in ceramic lining, residual stresses occur mainly in the cervical region and increase as the angle of inclination of the abutment walls decreases to 0° and reach maximum values with a fixed prosthesis on a single support — 7.88 MPa, on two supports — 10.34 MPa, and on three supports — 13.12 MPa (p≤0.05). With an increased diameter of the abutment support of 6 mm, the values of the stress-strain state are lower by 14.3% at all angles of inclination of the walls of the abutments (p≤0.05), in contrast to the values of the stress-strain state with an abutment with a diameter in the cervical region 4.5 mm. Also as the angle of inclination of the abutments decreases, there is increase in the stress-strain state in the metal frame in the cervical area and reach maximum values with a fixed prosthesis on a single support — 12.26 MPa, on two supports — 12.94 MPa, on three supports — 13.36 MPa (p≤0.05). >. The study of the stress-strain state of the abutments showed a surge of residual stresses in their upper part of a fixed prosthesis on a single support, on two supports, on three supports, reaching the highest values with an increase in the angle of inclination of its walls and the height of the abutment. So, already at a height of 7 mm and 8°, the obtained values (39.25 MPa) are 2.7 times higher than with an abutment with a height of 3 mm and a wall inclination angle of 10° (14.45 MPa; p≤0.05). It has been established that the height and angle of inclination of the abutment walls affect the uneven distribution of stresses in the ceramic veneer, framework, cement layer and abutment.