Allogenic lyophilized cartilage has been proven clinically to be a reliable material for obliteration of the frontal sinus without the limitations of donor site morbidity and the prolongation of the operation time produced by autogenic grafting. The long-term behaviour of the implanted material is of paramount importance for the success of the obliterative technique. This survey included 51 trauma patients on whom obliteration of the frontal sinus with lyophilized cartilage was performed. The fate of the lyophilized cartilage graft was evaluated from computed tomography imaging of the obliterated frontal sinus. No radiological sign of mucocele formation or inflammatory disease was noted. Bone density measurement of the obliterated sinus and the adjacent trabecular bone was calculated. The patient population was distributed into four groups (0-2, 2-4, 4-6, > 6 years) according the postobliterative time. The bone density of the implanted lyophilized cartilage was accentuated from group 1 to group 4 when compared with the bone density of the trabecular bone. This shows the long-term tendency of lyophilized cartilage graft to osseous substitution.