Orthodontic anchorage using mini-implants has established itself as an effective means of optimizing biomechanical control during orthodontic treatment. However, its success largely depends on the selection of the insertion site, as an inappropriate location can compromise anatomical structures and decrease primary stability. The purpose of this review was to identify the safest areas for mini-implant placement, integrating evidence published between 2010 and 2025. Studies using cone-beam computed tomography (CBCT), anatomical analyses, and systematic reviews that evaluated interradicular spaces, cortical thickness, and variations according to age, sex, and skeletal pattern were included. The results show that, in the maxilla, the safest interradicular spaces are located between the second premolar and first molar, as well as between the first and second molars on the buccal surface; in the anterior region, the appropriate site is between the central and lateral incisors, 6 mm from the cementoenamel junction. In the mandible, the preferred site is between the first and second molars, 6 mm or more apically, and in the anterior region, between the lateral incisor and canine. The paramedian region of the palate, especially between the first and second premolars, provides the thickest cortex and the greatest stability. Extra-alveolar alternatives include the infrazygomatic crest and the mandibular buccal cortex. In conclusion, although safe sites exist, mini-implant stability is influenced by individual anatomical factors, so individualized CBCT planning is recommended.