Structural stability of posterior retainer design for resin-bonded prostheses: a 3D finite element study

Abstract

The purpose of this in vitro study was to compare the stress distribution and natural frequency of different shape and thickness retainer designs for maxillary posterior resin-bonded prostheses using finite element (FE) method. A 3D FE model of a three unit posterior resin-bonded prosthesis analysis model was generated. Three different shaped retainer designs, viz. C-shaped (three axial surface wraparounds), D-shaped (three axial surface wraparounds with central groove) and O-shaped (360° wraparounds), and three different thicknesses, viz., 0.4, 0.8, and 1.2 mm, resin-bonded prostheses were used in this study. The resin-bonded prosthesis analysis model was imported into an FE analysis software (ANSYS 10.0, ANSYS, USA) and attribution of material properties. The nodes at the bottom surface of the roots were assigned fixed zero displacement in the three spatial dimensions. A simulated angle of 45° loading of a 100 N force was applied to the node of the pontic lingual cusp surface. The stress distributions and corresponding natural frequencies were analyzed and resolved. The C-shaped retainer for 0.4 mm thickness recorded the greatest von Mises stresses of 71.4 MPa for all three groups. C-shaped, D-shaped and O-shaped retainer presented natural frequencies 3,988, 7,754, and 10,494 Hz, respectively. D-shaped retainer and O-shaped retainer increased natural frequencies and structural rigidity over the traditional C-shaped retainer. The maximum von Mises stresses values of the remaining tooth and prosthesis decreased with greater retainer thickness. D-shaped retainer and O-shaped retainer increased natural frequencies and structural rigidity over the traditional C-shaped retainer.

Effect of different restorative crown design and materials on stress distribution in endodontically treated molars and peripheral bone: A finite element analysis study

“…The numeric FEA modeling is able to reveal the otherwise inaccessible stress distribution within the tooth-restoration complex. It has proven to be an important tool in the design process for the understanding of tooth biomechanics and the biomimetic approach (27,28) . Although teeth are 3-D structures, important mechanical events in endocrown and post-core crown appear within the mesiodistal plane (27,29) .…”

Fracture force for veneered materials on restorations measured by torsion testing

“…When a fixed partial denture is fitted in the mouth, shearing and bending stress are applied to it [27][28][29] , and this combination stress is believed to result in torsion stress. In the present study, a torsion testing device was used to measure the adhesive strength with respect to torsion at the interface between the veneering material and the base material.…”

“…However, such testing methodology cannot take into account the elasticity of the materials. While the use of bending tests 29) allows elasticity to be included in the analysis, torsion stress, which is believed to occur within the mouth, cannot be included.…”

Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures

“…In such patients, RBFPDs should be considered. Posterior RBFPDs not only need to be adequately adhered, but also require high mechanical strength to withstand dislodging forces ( 5 , 6 ). Therefore, RBFPDs with a metal-ceramic framework are still applied ( 7 – 9 ).…”

“…A typical choice for retainer design of posterior RBFPDs consists of two wraparound 180° lingual wings and two rests adjacent to the edentulous space ( 23 ). A number of previous studies and literature reviews ( 5 , 7 , 23 – 25 ) have introduced modified retainer designs, including an inlay retainer, a retainer with mesiodistal double rests on one abutment, C- or D-shaped retainers and dental bands designated O-shaped retainers. Nevertheless, there are no standard posterior porcelain-fused-to-metal (PFM) RBFPD designs currently available for clinical use.…”