rehabilitation with dental implants in posterior maxilla is difficult because of the presence of maxillary sinus with anatomical variations. the aim of this research was to evaluate the sinus volume to install one or more implants without invading the sinus membrane. forty (40) maxillary sinuses were evaluated in 22 skulls by computed tomography measuring in the axial, coronal and sagittal slice. the sinus were classified according to the remaining alveolar bone and a dental implant in the place of the upper first molar was virtually installed by implant view software. with this final volumetric measurement the surgical indications were established for inlay reconstruction from intra oral donor sites frequently evaluated in world literature. group i (1mm to 4mm of alveolar ridge) showed a bone deficit of 1.98 cm3, group ii (4mm to 7mm) showed a deficit of 1.06 cm3; group iii (7mm to 10mm) showed a 0.67 cm3 deficit. in view of these results we concluded that intra oral donor site can be used for the three study groups and in some cases in bilateral reconstruction.