The purpose of this study was to analye the risk  of the maxillary sinus lift technique, and the correlation between the thickness of the gingiva, maxillary sinus membrane and the maxillary sinus lateral wall. Cone-Beam Computer Tomograhy (CBCT)  records of 32 adult dentate patients (10 ♂ / 22♀) were analyzed. The gingival thickness records of the dental units were compared to the thickness measurements of the membrane and lateral wall of the maxillary sinus. The gingival biotypes varied between 1.1mm (thin)  and  1.6mm (thick) presenting a small association to sexes. The thickness of the sinus membrane presented small association between sexes (0.2mm♀ / 0.3mm♂) and gingival biotypes (Cohen’s D 0.52). The lateral wall presented a weak association between the biotypes (1.3mm-thin / 1.1mm - thick). There was also no correlation between the membrane and lateral wall (r = -0.22). The volume dimension related to the graft area of the sinus was 4mm³♂ and 5mm³♀. There was a weak correlation of gingival thickness compared to membrane thickness and lateral wall of the sinus (r = 0.304 / r = -0.31). Gingival thickness does not appear to be a reliable thickness predictor of the membrane or lateral wall of the maxillary sinus. The analysis of maxillary sinus anatomical structures through CBCT is the most reliable technique to identify the thickness of the membrane and  lateral wall of the maxillary sinus before surgery. We believe that new studies are necessary to confirm our findings.