To Evaluate and Compare the Effect of Proximal Wall Height on Stress Distribution at Occlusal Surface of Tooth and Prosthesis Core in Porcelain Fused to Metal and Veneered Zirconia Crowns: A FEA Study

Introduction:This study was undertaken to evaluate and compare stress distribution on tooth surface and core surface in porcelain fused to metal crown and veneered zirconia crown as a function of ratio of buccal axial length (BAL) to proximal axial length (PAL) with variations in loading condition and position using finite element analysis.Materials and methods: The geometric models of the prepared mandibular first molar and prosthesis were generated.Total six models were generated in accordance with the needs of the study.Three models were generated for veneered zirconia and three for veneered porcelain fused to metal.The proximal wall height variations used in the study were 3.0, 3.2, and 3.4 mm.Combined forces of 200 N vertical and 100 N horizontal were applied to the central groove, mesial incline and cusp center over a 1 mm diameter surface area on the veneer layer.Results: The maximum von Mises stress value was observed to be 39.691MPa at the cusp center of the tooth with a veneered zirconia crown at proximal wall height of 3.0 mm.The maximum von Mises stress value was observed to be 34.916MPa at the cusp center of a tooth with porcelain fused to a metal crown at proximal wall height of 3.0 mm.The maximum von Mises stress value was observed to be 34.214MPa at the cusp center of the tooth with a veneered zirconia crown at a proximal wall height of 3.2 mm.The maximum von Mises stress value was observed to be 28.365MPa at the cusp center of a tooth with porcelain fused to a metal crown at a proximal wall height of 3.2 mm.The maximum von Mises stress value was observed to be 29.729MPa at the cusp center of the tooth with a veneered zirconia crown at a proximal wall height of 3.4 mm.The maximum von Mises stress value was observed to be 27.25 MPa at the cusp center of a tooth with porcelain fused to a metal crown at a proximal wall height of 3.4 mm.The maximum von Mises stress value was observed to be 59 MPa at the cusp center of zirconia coping with a veneered zirconia crown at a proximal wall height of 3.0 mm.The maximum von Mises stress value was observed to be 48.619MPa at the cusp center of metal coping with porcelain fused to a metal crown at a proximal wall height of 3.0 mm.The maximum von Mises stress value was observed to be 57.516MPa at the cusp center of zirconia coping with a veneered zirconia crown at a proximal wall height of 3.2 mm.The maximum von Mises stress value was observed to be 37.423 MPa at the cusp center of metal coping with porcelain fused to metal crown at proximal wall height of 3.2 mm.The maximum von Mises stress value was observed to be 54.694MPa at the cusp center of zirconia coping with a veneered zirconia crown at a proximal wall height of 3.4 mm.The maximum von Mises stress value was observed to be 36.105MPa at the cusp center of the metal coping with porcelain fused to the metal crown at a proximal wall height of 3.4 mm.Conclusion: Maximum stresses were seen at the proximal wall height of 3.0 mm at the occlusal surface of the tooth in the veneered zirconia crown as compared to the proximal wall heights of 3.2 and 3.4 mm.Maximum stresses were seen at the proximal wall height of 3.0 mm at the occlusal surface of the zirconia coping in the veneered zirconia crown, as compared to the proximal wall heights of 3.2 and 3.4 mm.Maximum stresses were seen at the proximal wall height of 3.0 mm at the occlusal surface of a tooth in porcelain fused to a metal crown as compared to the proximal wall heights of 3.2 and 3.4 mm.Maximum stresses were seen at the proximal wall height of 3.0 mm at the occlusal surface of metal coping in porcelain fused to metal crown as compared to the proximal wall heights of 3.2 and 3.4 mm.When the proximal wall heights were compared maximum von Mises stresses were observed at the occlusal surface of the tooth with veneered zirconia crown as compared to the porcelain fused to metal prosthesis.When the proximal wall heights were compared maximum von Mises stresses were observed at the occlusal surface of zirconia coping in veneered zirconia crown as compared to the porcelain fused to metal prosthesis.The stresses increased as the proximal wall height was reduced.The maximum von Mises stresses were found at the cusp center, followed by mesial incline and central groove at all the variable proximal wall heights.