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ePaper created 2018-03-13, 09:28:55 | version 1.38.0
| research Fig. 1 Fig. 2 Fig. 3 Fig. 4 3. Alveolar corticotomy has limited effect in space The effects of alveolar corticotomy are localised to the area immediately adjacent to the site of injury.28 This finding is of outmost importance. Different surgeries may affect differently the resulting OTM. Glenn et al.29 and Tuncay and Killiany,30 in two experimental studies on animals published before the new trend on corti- cotomy, found that fiberotomy (a corticotomy limited to the crestal side of the alveolar bone) affected the rate of OTM and shifted the centre of rotation toward the apex of the roots, thus modifying the biomechanical behaviour of the teeth under the orthodontic forces. If the surgical insult is applied to a limited area of the alveolar bone (i.e. middle third and only buccal surface; Fig. 1), the RAP reaction will not be extended to the entire root area. The modifications at the bone level will be limited at the area of the decortication, and control of the apical and lingual sides will not be influenced as desired. As a general rule, if a mesiodistal bodily movement or better control of the apical area are the biomechanical needs of the OTM to be achieved and enhanced (i.e. intru- sion/extrusion), the decortication needs to be extended to the entire alveolar bone surrounding the roots of the teeth, buccally and lingually (Fig. 2); if the movement is less complex or anatomical limitations of the surgical site impede an extended decortication, the cuts may be lim- ited in the direction of the OTM. These biomechanical needs determine the type of procedure in both the open- flap and the flapless surgeries. 4. A proper surgical procedure must be followed Several surgical protocols for performing alveolar cor- ticotomy have been proposed. Most of them have been tried in the last 15 years on several patients. These sur- geries may be divided into two groups: the open-flap and the flapless corticotomies (Tab. 1). The original corticotomies were performed after rais- ing a flap. This type of surgery is still preferred when an extended or critical area of decortication has to be man- aged and when an extended grafting is planned. The flap can be designed according to the periodontal characteristics of the site and has to be full thickness in the area of decortication and split thickness below this area to ensure a good blood supply. Interproximal and subapical cuts of 1–2 mm in the cortical bone (Figs. 3 & 4) are performed together with a light scraping of the exter- nal cortex in between the cuts. This extended surgical insult will produce a wide RAP reaction and prepare a bleeding bed for any grafting material eventually placed 22 ortho 1 2018