The aim of this systematic review was to evaluate proper site for orthodontic mini-implant placement and Does bone density vary in anterior and posterior region or buccal and palatal region in maxilla and mandible. In this systematic review, 15 In vivo studies and 2 In vitro studies were included. Data from a total of 1277 patient's radiograph were included in this review out of which 821 are CBCT scan and 456 are CT scan. The density and site suitable for the orthodontic mini-implant placement is examined. In conclusion, males have a thicker and higher density alveolar cortical bone than females. Adult show a thicker alveolar cortical bone than adolescents. In the mandible, the alveolar cortical bone is more compact and thicker than in the maxilla. High value of thickness and density characterize posterior regions of both jaws. Palatal bone is thicker than the buccal cortical bone. There is a significant linear increasing of thickness and density from crest to base of alveolar crest.