Background: 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. Besides all-ceramic material, polyetheretherketone (PEEK) material have widely been used on medical field. PEEK provides a shock absorbent effect, biocompatible with good esthetics
which can be considered as an alternative restoration material. Objectives: 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) Material and Method: 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. Result: Stress on zirconia and lithium disilicate crowns was localized on occlusal loading area as well as 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) compared to chamfer (22,264 MPa), and both lithium disilicate (14,039 MPa) and PEEK (0,444 MPa) crown with chamfer finish line design compared to shoulder lithium disilicate (16,496 MPa) and PEEK (0,473 MPa). 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. 
Conclusion: PEEK crown prevent stress concentration on crown cervical area, implying PEEK can be use clinically as alternative restoration material.