Analisis Distribusi Tegangan Restorasi Mahkota Posterior Zirkonia, Lithium Disilicate dan Poly Ether Ether Ketone (PEEK) dengan Desain Akhiran Preparasi Menggunakan Finite Element Analysis

Abstract

All-ceramic crown restorations frequently used in prosthodontics as metal-free restoration because of their esthetics, biocompatibility, and inert properties, however fracture remains a complication. Stress distribution in all-ceramic crowns during mastication reported to be higher on cervical area than occlusal surface according to finite element analysis (FEA). Cervical area are vulnerable and may induce cracks from the occlusal surface to cervical. Shoulder and chamfer finish line design were recommended design for crown restoration and had influence in stress distribution. Mechanical properties of restoration material such as modulus elasticity is an important factor that must be considered. Polyetheretherketone (PEEK) material have widely been used on medical field and nowadays on dentistry because of its properties. PEEK provides a shock absorbent effect, biocompatible with good esthetics which can be considered as an alternative restoration material. This study aims to analyze zirconia, lithium disilicate and PEEK posterior crown restoration stress distribution with finish line design using FEA software (ANSYS v17.2; ANSYS Inc, Canonsburg, PA, USA). Six 3D mandibular first molar models of two type finish line designs; shoulder and chamfer were prepared using AutoCAD 2016 software and crown restoration 3D designed. FEA simulation then started with loading condition, simulating average human maximum bite force of 600 N axially to the occlusal surface at the center of the crown. For zirconia and lithium disilicate crowns, stress was localized to the occlusal loading area as well as to the internal restoration axial wall and cervical region within restoration. Contrastly for PEEK crown, stress got absorbed and disperse to the underlying abutment. The lowest von Mises stress values showed on zirconia crown with shoulder finish line design (20,301 MPa), and both lithium disilicate (14,039 MPa) and PEEK (0,444 MPa) crown with chamfer finish line design. These result suggest that on zirconia crown, it needs a wide margin area such as shoulder finish line design to minimize stress, meanwhile on lithium disilicate and PEEK crown, chamfer finish line design distribute stress evenly so that crown restoration survival can be expected to improve. PEEK crown also prevent stress concentration on crown cervical area, implying PEEK can be use clinically as alternative restoration material.