Effect of three different veneering techniques on the stress distribution and in vitro fatigue behavior of core-veneer all-ceramic fixed partial dentures

Abstract

Background. The present study aimed to evaluate the influence of the veneering technique on the tensile stress distribution and survival of full-ceramic fixed dental prostheses (FDPs). Methods. A three-dimensional model of an FDP was modeled on a second premolar and a second molar with a pontic between them for finite element analysis (FEA). The groups were divided according to the veneering technique: conventional stratification, rapid layer, and CAD-on techniques. A mesh control test determined the number of elements and nodes. The materials’ properties were attributed to each solid component with isotropic, homogeneous, and linear elastic behavior. For the in vitro fatigue test (n=30), the FDPs were cemented on dentin analog abutments and submitted to 2×106 mechanical cycles (100 N at 3 Hz). Results. Maximum principal stress showed that the connector between the pontic and the second molar concentrated higher stresses, regardless of the techniques: Rapid layer (6 MPa)> CAD-on (5.5 MPa)> conventional stratification (4 MPa). The conventional stratification technique concentrated high stresses at the interface between the framework and veneering ceramic (2 MPa), followed by the rapid layer (1.8 MPa) and CAD-on (1.5 MPa) techniques. The crowns fabricated using the rapid layer and CAD-on techniques exhibited a 100% survival rate, while the conventional stratification group had 0% survival. Conclusion. Even with similar stress distribution between the veneering techniques, the conventional stratification technique was more prone to failure under fatigue due to higher defects incorporated than CAD-on and rapid layer techniques.

Substrate Rigidity Effect on CAD/CAM Restorations at Different Thicknesses

“…The elastic modulus and Poisson ratio used for the calculation were based on previous reports from the literature ( Table 2 ). 2 13 21 22 The compressive load of 100 N was used to perform an individual simulation and to obtain a specific value in MPa. The stress distribution data were exported and plotted as colorimetric stress maps.…”

“…9 Additionally, it is well known that indirect restorations adhesively cemented to enamel presents reliable bond strength and long-term durability. [1][2][3][4][5][6][7][8][9] Despite the success of adhesive dentistry, it is not rare that after the tooth preparation, the substrate is not only in enamel, thus it is not always in the most suitable condition for the best bonding procedure. 10 In cases, for example, after endodontic treatments, it is common for the clinician to fill the access cavity with direct restorative materials (e.g., glass ionomer cement [GIC], resin composite [RC]).…”

“…9 One of the most reliable methods to investigate the stress field is the finite element analysis (FEA). 2,3 This methodology is a biomechanical tool based on a numerical calculation considering the setup of geometrical model and the mechanical properties of the investigated materials. FEA can show, with qualitative and quantitative results, the biomechanical behavior of different conditions in direct and indirect restorations.…”

“…9 Additionally, it is well known that indirect restorations adhesively cemented to enamel presents reliable bond strength and long-term durability. 1 2 3 4 5 6 7 8 9…”

“…FEA can show, with qualitative and quantitative results, the biomechanical behavior of different conditions in direct and indirect restorations. 2 9 11 14 17 18…”