Objective of this retrospective study was to measure cortical bone thickness and lowest level of maxillary sinus at maxillary posterior quadrant in different growth pattern (hypodivergent, average, and hyperdivergent) at prospective microimplant placement sites in order to understand both safety and stability aspects of microimplant placement by using cone-beam 3-dimensional computed tomographic images. In posterior quadrant, vertical distance from cementoenamel junction to lowest level of maxillary sinus at interradicular region was measured. Buccal cortical bone thickness was measured at 3 different vertical levels at interradicular space. The cortical bone thickness was found more at sinus floor level and above it than below the sinus floor. In perspective of miniscrew placement, study shows that maxillary sinus floor is safer with average and hyperdivergent growth pattern than hypodivergent growth pattern. In the proximity of maxillary sinus floor, 1 mm or more cortical bone can be expected in maxillary posterior region in average and hyperdivergent growth patterns. However, it was thicker in hypodivergent than hyperdivergent growth patterns. Hypodivergent patients require either more horizontal insertion (more parallel to occlusal plane) or shorter length of miniscrew to avoid damage to maxillary sinus.