# A Brief Review on Micro-Implants and Their Use in Orthodontics and Dentofacial Orthopaedics
## 3 Results
### Anatomical and Surgical Details  
Over time, several methods have been devised and developed to avoid accidents using micro-implants, the most important being damage to the roots of the neighboring teeth. A precise surgical plan before OMIs' insertion is crucial. Some researchers described the use of radiographic templates and film holders to make a surgical template for guiding OMIs' insertion [12]. The success rate of OMIs was tested by using panoramic radiographs that showed the position and angulation of the screws [6]. The overall success rate was higher for people more than 20 years old and screws on the left side, for the women than for the men, for extraction than for non-extraction group, for OMIs placed on the interradicular midline. OMI success rate significantly increased with an increase in the OMI length and placement height, and with a lesser angulation [6]. Other authors claimed that compared with panoramic radiographs, cone beam computed tomography (CBCT) images can provide more accurate information regarding tooth position, root resorption, and various pathologies; the radiation exposure is less and the cost is lower using panoramic radiographs, which provides acceptable reliability [9]. The efficacy of optical coherence tomography (OCT) was tested comparatively with that of micro-computed tomography (uCT) [13] to detect and analyze cortical bone micro-damage immediately after insertion. The visualization of individual microcracks was highly correlated. Even if the depth penetration of OCT was more limited, it has been able to give high-resolution images of the bone microdamage occurring around the micro-implant. Image quality at the surface of the cortical bone is better when compared with uCT imaging, because of the high contrast and the high-resolution quality of OCT systems [13]. The surgical insertion procedure showed contradictory results between flap or without flap techniques on mandibular mini-implants. Loading and healing periods were not significant in the mini-screws success rates [7]. When using micro-implants is important to evaluate the cortical bone thickness and the interradicular spaces to create enough stability for the application of orthodontic forces. [PERSON] and [PERSON] [8] found using cone-beam 3D images that in the posterior dentition area the buccal cortical bone is 1 mm or thicker, 1.12 to 1.33 mm for maxilla, and 1.25 to 2.98 mm for mandibula. The cortical bone becomes thicker progressively from the cement-enamel junction to the apical zone. The interradicular distances varied from 1.6 to 3.46 mm in the maxilla with a maximum between the second premolar and the first molar. In mandibula, the interradicular distances were greater than in maxilla and ranged between 1.99 and 4.25 mm. The retromolar zones showed cortical bone from 1.96 to 2.06 mm thicker. The widths of alveolar processes were 3.74-5.78 mm for the maxilla and 3.11-7.84 mm for the mandibula. The mid-palatal area at 20-25 mm posterior than foramen incisivum ranged from 7.04 to 6.99 mm. They concluded that a better location for placing micro-implants was buccal between the second premolar and the first molar for maxilla, buccal from the first premolar to the second molar for mandibia, palatal between molars for maxilla, the mid-palatal and retromolar areas [8]. The cortical bone thickness of the inter-dental area of maxilla and mandible for orthodontic micro-implants placement was investigated by cone-beam computerized tomography [14] by a study that was performed on 32 non-orthodontic adults with normal occlusion. Buccal cortical bone was thicker in the mandible. In the maxilla, the cortical bone was thicker buccal than palatal. In the mandible, the buccal cortical bone was thickest distal to the first molar, and in the maxilla, it was thickest mesial to the first molar; in the palatal side of maxilla, the cortical bone was thickest mesial to the second premolar.