Twenty four patients will be selected analysing the resorption on the front maxilla and will be divided into two groups. Experimental group will receive a particulated mixture of autogenous and lyophilized bovine bone, stabilized with a collagen membrane and pins over the vertical and/or horizontal defect, while Control group will receive a bone block graft, stabilized with fixation screws , covered with lyophilized bone and a collagen membrane. After a period of nine months, the volume increase will be measured trough the difference found between the initial computerized tomography and the final computerized tomography.