We study the roughness of fracture surfaces of three-dimensional samples through numerical simulations of a model for quasi-static cracks known as Born Model. We find for the roughness exponent a value ζ ≃ 0.5 measured for "small length scales" in microfracturing experiments. Our simulations confirm that at small length scales the fracture can be considered as quasi-static. The isotropy of the roughness exponent on the crack surface is also showed. Finally, considering the crack front, we compute the roughness exponents of longitudinal and transverse fluctuations of the crack line (ζ_∥ ~∼ ζ_⊥ ∼ 0.5). They result in agreement with experimental data, and support the possible application of the model of line depinning in the case of long-range interactions.