Stress Distribution on the Dentin/Adhesive Interface Varying the Dentin Depths

OBJECTIVES: There are no numerical studies about the influence of the diameter and number of the dentin tubules on the stress distribution according to dentin depths. We hypothesize that microstructure of dentin may affect the stress transfer pattern, which can be most influenced by deeper dentin. The aim of this study was to analyze the stress distribution at the dentin/adhesive interface (d/a) through 3-D finite element analysis (FEA) with different dentin depths, varying the number and diameter of the dentin tubules, keeping constant the hybrid layer thickness (HL) and TAGxs length (3µm and 17µm, respectively). METHODS: 3 3-D FEA models (M) of dentin specimen (41 x 41 x 41 µm, HL = 3 µm and TAG = 17 µm) restored with a composite resin were built varying the diameter (d) and the number (#) of the dentin tubules: M1 – superficial dentin, #=8, and d=0,9 µm; M2 – medium dentin, #=12, and d=1,2 µm; and M3 – deep dentin, #=16, and d=2,5 µm. The principal stress in tension (σmax) was obtained using ANSYS. The distributed loading (L) was performed on the top surface of the composite resin.RESULTS: The higher σmax was found in the deep dentin, followed by superficial and medium dentin (M1=3,283 MPa; M2=7,346 MPa; M3= 8,084 MPa). The peak of σmax was in the peritubular dentin for all models. The stress pathway (from the higher σmax location to the lower) was similar among the models: peritubular dentin, adhesive layer, inter-tubular dentin and hybrid layer. CONCLUSIONS: Increasing the number and diameter of the dentin tubules, the σmax increased at the d/a interface. The σmax variation was more evident in the peritubular dentin. (Supported by FAPESP 2006/01988-6)