*5.3.1 Standard Le fort I osteotomy*

An adolescent or adult CLP patient who has maxillary deformity but no residual fistula, in addition to an intact alveolar ridge with an adequate height in the cleft region may have been born without an alveolar cleft or had a successful grafting procedure [42]. A standard Le Fort I osteotomy may be applied on individuals who

have sufficient alveolar ridge height and volume, a close palate and sufficient periodontal support. Segmental maxillary osteotomy may also be needed in correction of arch width, repairing vertical dimensions or preventing the need for prosthetic lateral incisors by closing the cleft-dental gap.

Unfortunately, even in the twenty-first century, alveolar defects and oronasal fistulae are encountered in many adults and adolescents who have UCLP with maxillary hypoplasia. For these patients, a modified Le Fort I osteotomy should be considered [17].

## *5.3.2 Modified Le fort I osteotomy (two-segment)*

In UCLP patients, the gap of the missing lateral incisor tooth may be eliminated by advancement of the lateral alveolar bone segment, where the canine tooth is placed adjacent to the central incisor tooth. After this, the canine is formed in a similar appearance to that of the lateral incisor [47]. This method that was described by Obwegeser in cases of unilateral cleft was advanced by Posnick in 1992 and name as the modified Le Fort I osteotomy method [46].

In the technique, first, a maxillary circumvestibular incision is made labially from a zygomatic buttress to another. In the residual oronasal fistula region, vertical incisions are made to separate the mucosa on both sides of the cleft as oral and nasal. These incisions are perpendicular to the horizontal vestibular incision, and they follow the line angles of the teeth adjacent to the cleft (central and canine). If the cleft bone was not previously repaired, the segments are already in two pieces with the down-fractured maxilla. If the maxilla is intact and the arch form needs to be adjusted, by using a reciprocating saw with a short and flat tip, the maxilla is divided into two pieces by cutting from the cleft area. The parts need to be brought closer to close the cleft-dental gap. However, this may be achieved only after shaving in the distal direction of the central incisor and along the mesial part of the canine from the alveola. Attention should be paid to ensure avoiding contact with the lamina dura as it would expose the root of teeth and may result in external root resorption. The maxillary segments are then stabilized with wires and acrylic occlusal splints. Repositioning of the segments closes the cleft-dental gap, gathers the alveolar ridges together, and gets the labial and palatal mucosal tissues closer for oral-fistula closure [17].

The extent of the maxillary advancement that is carried out by the surgeon is based on previously planned occlusion, airway needs, and preoperatively determined facial esthetics. The ideal vertical dimension is achieved based on the preoperative plan, but intraoperative approaches may be considered in some cases [35]. Maxillary osteotomy regions are fixed on all zygomatic buttresses and apertures by using titanium plates and screws based on the principles described by Luhr [48, 49]. If a graft has been used, an extra microplate is additionally applied to stabilize each interpositional cortico-cancellous (iliac) graft. For repairing facial asymmetries and secondary deformities, mandibular and jaw osteotomies are also frequently required in UCLP patients in addition to Le Fort I osteotomy.
