# A Brief Review on Micro-Implants and Their Use in Orthodontics and Dentofacial Orthopaedics
## 3 Results
### Use in Orthodontic Clinical Practice and Dento-Facial Orthopedics  
Micro-implants could help orthopedic and skeletal modifications. Micro-implant-assisted rapid palatal expanders variable as design and using protocols were used for the treatments of Class III [3]. By fixing with micro-implants transversal screws to the hard palate the rapid palatal expansion prevents the tipping of the anchorage teeth, tooth mobility, and resorption of roots and bone which are accidents in using conventional rapid palatal expenders (RPE) [41; 42; 43]. Computer tomography and Mimics modeling software, ANSYS simulation software showed that compression and tension forces are directed to the palate bone and produced less rotation or tipping of the maxillary complex in case of using micro-implant-assisted rapid palatal expansion (MARPE) compared to use of conventional rapid palatal expander (RPE) [44]. MARPE made the maxilla bend laterally and prevented unwanted rotation of the maxillary complex, the vertical maxillary dropping [44]. The MARPE was described as efficient in adolescents and an adult-case patient (19 years old) where the palatal anchorage was performed by using four micro-implants. The palatal bones were expanded by \(5.41\,\pm\,2.18\,\mathrm{mm}\) and \(10\,\mathrm{mm}\), respectively [45]. The cross-sectional CT showed the expansion of maxillofacial structures, zygoma, and nasal floor, and the widening of circum-maximillary sutures; the alveolar bone maintained its integrity even the teeth tipped in vestibular direction. The dentoalveolar side effects were minimum: the first molars exhibited buccal tipping of \(2.56\,\pm\,2.64^{\circ}\)[46]. Another study [47] contradicted these results by finding 41% skeletal enlargement, 12% alveolar bone bending, and 48% dental tipping after MARPE. The mid-palatal suture opening was parallel in both axial and coronal planes. The dental tipping was \(4.17^{\circ}\) to \(4.96^{\circ}\) and the buccal bone thickness was reduced by an average of 39% measured at the molars and the premolars [46]. MARPE appears to be an alternative to surgical treatment in the correction of moderate transverse deficiencies in skeletally mature adult patients [43; 44; 45; 46; 47]. Micro-implant-supported midfacial skeletal expanders that had been used as anchorage four OMIs (\(1.8\,\mathrm{mm}\) in diameter, \(11\,\mathrm{mm}\) or \(13\,\mathrm{mm}\) in length) inserted through the palatal bone, bi-cortically, produced almost pure skeletal rotational movement of the mid cranial structures [48]. Alveolar bone bending and dental tipping were not statistically significant. The localization of the rotational fulcrum of the zygomaticomaxillary complex should be the first step to differentiate the expansion pattern, than angular measurements should be performed. The angular measurements for fulcrums gave very different results than the conventional linear measurement system that can falsely exaggerate the alveolar and dental components of midfacial skeletal expansion [48]. Micro-implant-assisted expanders have proved significant effects on the mid-face, with a degree of asymmetry [49]. On non-growing patients, CBCT images showed a statistically significant difference between the average magnitude of the total expansion of \(4.98\,\mathrm{mm}\) at the anterior nasal spine and the average of \(4.77\,\mathrm{mm}\) at the posterior nasal spine. Among the asymmetric patients, one-half of the anterior nasal spine moved more than the contralateral one by \(2.22\,\mathrm{mm}\). The expansion achieved was 96% parallel in the antero-posterior direction. The palatal bone and soft tissue thicknesses were investigated by cone-beam computerized tomography, using a micro-implant-supported maxillary skeletal expander in Class III malocclusion on 58 patients [50]. The antero-posterior reference that has been used was the line connecting the central fossae of the first molars (Level 0).