Finite element analysis of thermo-debonding mechanism in dental composites

Finite element method (FEM) has been extensively used for evaluating interf acial status inside biomaterials. This study using FEM was designed to eval uate the thermal stress behavior of a filler-matrix interface. The results were then compared to those of a previous study obtained by a laser thermoa coustic technique (LTAT). The experimental systems (75/25 Bis-GMA/TEGDMA re sin reinforced with 0, 25, 50, and 75 wt% 8-mu m silanized/unsilanized BaSi O6) as used in the previous study were modeled in this study. The establish ed finite element models were based on coefficient of thermal expansion (CT E) Mismatch Phenomenon. The mechanical properties of the silane coupling ag ent, such as elastic modulus and thermal expansion coefficient used in the silanized model, were assumed to have optimal heat flux transfer. A third ( imaginary) material was proposed to block the transfer of thermal stress be tween the filler and matrix in the unsilanized model. The thermal load simu lation was based on steady-state thermal analysis. The results showed that: (1) The strain energy and interfacial shearing stress calculated from FEM validate the results from the previous LTAT study. (2) Comparing the stress distribution of silanized and unsilanized FEM models, the acoustic signals in LTAT study are mainly derived from debonding of the filler-matrix inter face of silanized specimens, and from the matrix area of unsilanized specim ens. Based on results to date. we conclude that the finite element method m ay be a powerful tool for exploring thermoacoustic mechanisms of dental com posites. (C) 2000 Elsevier Science Ltd. All rights reserved.