Mechanical Evaluation of Two Different Zirconia-Reinforced Lithium Silicate Ceramics: A Finite Element Analysis

Objective: The aim of the study is to evaluate the stress distribution of zirconia-reinforced lithium silicate all-ceramic fixed partial dentures under occlusal loading; in terms of material, restoration, and supporting type. Methods: Six different models were analyzed; tooth-supported anterior crown, tooth-supported posterior crown, tooth-supported 3-unit bridge, implant-supported anterior crown, implant-supported posterior crown and implant-supported 3-unit bridge. Milling and pressable zirconia-reinforced lithium silicate were used in each model. Structural analyses were simulated with finite element analysis under vertical and oblique loading to evaluate the von Mises and minimum principal stresses. Results: Tooth-supported restorations showed lower stress values than implant-supported forms of the same restoration. Stresses were higher and distributed over a larger surface under oblique loading compared to vertical loading. Overall stresses generated on the single crown models were higher than the stresses generated on the bridge models. Implant-supported bridge model under oblique loading shows the highest stress. However both milling and pressable forms of zirconia-reinforced lithium silicate didn’t make a difference on the stress concentration and distribution areas. Conclusion: The stress distribution and mechanical behavior of models was influenced by the type of restoration, direction of the force, and the number of units. However, no significant difference was found between milling and pressable zirconia-reinforced lithium silicate ceramic in terms of the stress values on the restorations.