Fatigue failure of dentin–composite disks subjected to cyclic diametral compression

Abstract

Objective Our aim was to establish the relationship between cyclic loading and fatigue life of the dentin-composite interface using the newly developed disk in diametral compression tests. The results were then used to estimate the fatigue life of restored teeth under occlusal loading. Methods Disk specimens (5mm dia. × 2mm thick) were prepared using bovine incisors and restored with either a methacrylate-based composite Z100™ with Adper Single Bond Plus (Z100) or silorane-based composite Filtek ™ LS with LS System adhesive (LS). The dentin-composite disks were tested under cyclic diametral compression to determine the number of cycles to failure (Nf) at three load levels (n = 3 per group). Finite element analysis (FEA) was used to calculate the interfacial stresses (σ) within the specimen, to establish the σ vs. Nf curves, and those within a restored tooth under normal chewing forces (15N maximum). These were then used to estimate the lifetime of the restored tooth for the two restorative systems. Results The disks restored with LS had a higher fatigue resistance than those restored with Z100. The maximum interfacial stress in the restored tooth determined by FEA was ∼0.5MPa. Based on the estimate of 300,000 cycles of chewing per year, the predicted lifetime under occlusal loading for teeth restored with LS and Z100 was 33 and 10 years, respectively. Significance The disk in cyclic diametral compression has been used successfully to provide fatigue data which allows the lifetime of composite-restored teeth under occlusal loading to be predicted using numerical simulation.

Modeling and validation of a 3D premolar for finite element analysis

“…In Dentistry, the technique began to be studied in the 1970s 1 . The methodology has great versatility and analyzes the stresses produced in numerical models; it can be applied in research fields such as implantology 2 , orthodontics 3 , it can also simulate thermal 4 mechanical cycling 5 , water sorption 6 and polymerization shrinkage 7 and can also be applied in cavity optimization 8 and cusp bending 9 studies.…”

Accelerated fatigue testing of dentin-composite bond with continuously increasing load

“…(9). The load-to-stress proportionality constant, k s , had previously been determined for the dentin-composite disc using the finite element method to be 0.035 MPa/N [17].…”

“…In total, 60 dentin-composite disc samples were prepared using bovine incisors as described previously [17,23,27]. Root sections from below the cementum-enamel junction with a root canal diameter less than 2 mm and an outer diameter larger than 5 mm were used.…”

“…To expedite the process, therefore, load levels successively higher than that experienced clinically can be used to determine the dependence of the fatigue life on the load level [14]. Predictions can then be made through extrapolation for the clinical situation [15][16][17][18]. Alternatively, the step-stress method [19,20] can be used to accelerate the fatigue test.…”

“…Dentin-composite discs under diametral compression [17,23] are used to create tensile stresses at the interface to cause debonding. A probabilistic model based on the Weibull function [24] and Basquin's stress-life relationship [25] is also developed to analyze the data.…”