Biomechanical behavior of posterior metal-free cantilever fixed dental prostheses: effect of material and retainer design

Abstract

Objective To study the fracture resistance and stress distribution pattern of translucent zirconia and fiber-reinforced composite cantilever resin-bonded fixed dental prostheses (RPFDPs) with two retainer designs. Materials and methods Forty human mandibular molars were divided into two groups according to the retainer design. The restorations included a premolar pontic and 2 retainer designs: (D1) inlay ring retainer and (D2) lingual coverage retainer. Each main group was then divided according to the material used (n = 10): zirconia (Z) or fiber-reinforced composite (FRC) (F). Restorations were cemented using dual polymerizing adhesive luting resin. All specimens were thermo-cycled (5–55 °C for 10,000 cycles), then subjected to dynamic loading (50 N, 240,000, and 1.6 Hz) and fracture resistance test. The finite element analysis includes the two models of retainer designs used in the in vitro test. Modified von Mises stress values on enamel, dentin, luting resin, and restorations were examined when the restorations failed. Results A significantly higher failure load was recorded for zirconia groups (505.00 ± 61.50 and 548.00 ± 75.63 N for D1Z and D2Z, respectively) than for FRC groups (345.00 ± 42.33 and 375.10 ± 53.62 N for D1F and D2F, respectively) (P = 0.001). With regard to failure mode, D2 showed a more favorable failure pattern than D1. Model D2 resulted in lower stresses in tooth structure than model D1, and zirconia transmitted more stresses to the tooth structure than FRC. Conclusions The lingual coverage retainer (D2) enhanced the biomechanical performance of the restoration/tooth complex. Considering the failure mode and tooth stress, FRC is a promising treatment option when constructing a cantilever RPFDP. Clinical relevance Dentists should be aware of the biomechanical behavior during the selection of the material and for the replacement of a single missing mandibular premolar tooth with minimally invasive RBFDP.

The Use of Polyetheretherketone (PEEK) as an Alternative Post and Core Material: Five-Year Follow-Up Report

“…It was reported that a thinner cement layer reduces the polymerization shrinkage stress, increasing therefore the final bond strength [ 37 ]. Additionally, multiple factors can affect the fracture strength of prostheses, including the force of applied load, cement type and technique as well as the elastic modulus of the structure [ 38 ].…”

Influence of retainer design and number of inlay boxes on the biomechanical behavior of zirconia cantilever resin bonded fixed dental prosthesis

“…26 The teeth were inspected visually and throughout the preparation process using the transillumination technique. 3 Finally, disinfection of the teeth was done using 1:10 diluted sodium hypochlorite (5.25%) solution. 3,10 To facilitate handling throughout the preparation, scanning, and bonding procedures, the teeth were inserted vertically into acrylic resin blocks.…”

“…3 Finally, disinfection of the teeth was done using 1:10 diluted sodium hypochlorite (5.25%) solution. 3,10 To facilitate handling throughout the preparation, scanning, and bonding procedures, the teeth were inserted vertically into acrylic resin blocks. Using the transitional wax technique, a consistent layer (0.3 mm) of light-body polyvinyl siloxane impression material (Ghenesyl Superlight, Lascod, Italy) was added around the roots and then enclosed by cylindrical acrylic resin block (26 mm diameter and 20 mm height).…”

“…25,26 Finite element analysis (FEA) can be utilized to supplement and enhance the results of in-vitro investigations. 3,10,27 FEA is numerical simulation of various materials, techniques, and designs in terms of stress concentration and displacement under different loading conditions. It allows for the examination and assessment of the biomechanical features of dental restorations as well as the supporting dental tissues.…”

Cantilever resin-bonded fixed dental prosthesis to substitute a single premolar: Impact of retainer design and ceramic material after dynamic loading

“…There are diverse treatment alternatives in dentistry for the rehabilitation of posterior tooth loss, including implant-supported prostheses, conventional fixed dental prostheses (FDPs), and resinbonded fixed dental prostheses (RBFDP) [1][2][3]. Among tooth-supported restorations, FDP is the most invasive option because crown preparations have been reported to require removal of 50-70% of the total sound tooth structure, and the possibility of endodontic treatment might be increased primarily in the anterior and premolar regions [4][5][6].…”