Porcelain sectional veneers, an ultra-conservative technique for diastema closure (three-dimensional finite element stress analysis)

摘要

Background . Diastema can be closed using conservative and non-conservative techniques. Composite resin wings and ceramic veneers are the most common treatment options if there is no indication for orthodontic treatment. A novel ultra-conservative technique has been introduced to the practice, i.e., porcelain sectional veneers can be fabricated with no or minimum preparation. However, porcelain is known for its poor mechanical properties and the long-term survival of such restorations is questionable. Objectives . This paper aimed to investigate the mechanical aspects of porcelain sectional veneers by means of the finite element method (FEM). Material and Methods . A three-dimensional (3D) model of porcelain sectional veneers on the upper central incisors with diastema was obtained by the reversed engineering method starting from a cone-beam computed tomography (CBCT) image. A 100 N occlusal force was applied parallel and 135° to the longitudinal axis, respectively. For each direction the force was applied once with direct contact and again with no contact with the porcelain sectional veneers. For each of the resulting 4 scenarios, a 3D finite element analysis was simulated and the maximum equivalent von Mises stress was compared to porcelain flexural strength. Results . Higher stresses were detected when the force was applied on the porcelain sectional veneers and they were increased dramatically with the inclined force. Conclusion . Direct occlusal contact has to be avoided when using porcelain sectional veneers and the margin positions must be chosen carefully. The occlusal scheme must be noted carefully before choosing this type of restoration.