Le Fort I osteotomy

10.1 Indications

Key words: intramaxillary disharmony, lip closure insufficiency, maxillary advancement, maxillary cranial and caudal displacement; clefts of lip, alveolus, and palate; sagittal malgrowth of the maxilla, vertical malgrowth of the maxilla

Surgical relocation of the maxilla is indicated if, in addition to a malocclusion, the bony midface shows facial skeletal abnormalities. The sole Le Fort I osteotomy is performed with complete mobilization of the maxilla (downfracture included) in order to adapt the maxillary dental arch to the mandibular dental arch in neutral occlusion. Due to sagittal misgrowth of the midface, more frequent forward and less frequent backward displacements of the maxilla may be necessary to establish a neutral occlusion to the mandibular arch. This can also be the case in clefts of lip, alveolus, and palate.

Vertical changes of the maxillary position with autorotation of the mandible to achieve a neutral occlusion are also possible. Thus, cranial or caudal displacements of the maxilla may be indicated. However, maxillary displacements can also be performed without occlusal changes if only vertical hyperplasia with lip closure insufficiency is an indication for maxillary intrusion. However, since the simultaneous often desirable enlargement of the mandible by autorotation of the mandible is only slight, the indication for Le Fort I osteotomy alone is rarely given for these reasons.

It is also conceivable that a Le Fort I osteotomy may be necessary to correct excessive “long centric” (centric to habitual intercuspidation).

If there are maxillomandibular disharmonies with incongruence to the mandibular dental arch, multiple division of the maxilla in the course of a Le Fort I osteotomy is a frequent indication in order to achieve congruence to the mandibular arch and a neutral occlusion by adjusting standardized (osteotomies between teeth 12/13 and 22/23) three-part or individual tooth-bearing maxillary segments.

Indications for Le Fort I osteotomy are more extensive in the context of a maxillomandibular osteotomy because the entire maxillomandibular block is displaced three-dimensionally (see Chapter 6).

10.2 Methodology

Key words: bone graft, downfracture, gingival margin incision, MMF screws, infraorbital nerve exposure, glabellar circle measurement method, local anesthesia, longitudinally oscillating osteotomy, maxillary caudal displacement, maxillary cranial displacement, minimally invasive incision, miniplate osteosyntheses, mucogingival margin, palatal nerve exposure, piezoelectric bone transection, release of the tuberosity, single-link hook, surgical splint, suture closure, wire slings, vestibular mucosal incision

Injection is performed of local anesthetic and vasoconstrictor (eg, Xylonest 1% with epinephrine 1: 200,000) in the maxillary vestibule from region 16 to 26, at the anterior nasal spine and into the mucosa of the caudal septum on both sides, and insertion of epinephrine-soaked pointed swabs into the inferior nasal passages to reduce bleeding and reduce the amount of narcotic agents at the start of surgery.

The first action is the determination of the midface height to adjust the maxilla at the same level or higher or deeper depending on the operation planning. A reference pin is clocked stably in the bony surface of the glabella region and remains until the end of the operation. The distance from the reference pin to the brace fixing wire is measured by an ascertainable circle (see Fig 10-2a) and is transferred to a ruler (Medicon). Either the maxilla is exposed with the scalpel through a gingival margin incision from region 17 to 27 with distobuccal relief into the tuberosity region, or it is opened with the scalpel or electrically through a mucosal incision through the vestibulum approximately 4 mm cranial to the mucogingival border from region 16 to 26. In the case of minor bony displacements of the maxilla, if a complete downfracture can be avoided, a minimally invasive approach is also possible on both sides in the lateral maxillary vestibule while retaining a medial mucosal bridge. In multi-unit maxillary osteotomies, no gingival margin is indicated to preserve maxillary blood supply (for more detail, see Chapter 11).

The level of midface osteotomy is illustrated by the anatomical drawings in Fig 10-1. Five bony walls are transected in the transverse plane, the two lateral and the two medial maxillary sinus walls and the septum. Figure 10-1b shows the horizontal section through the midface visible in the cranial direction after maxillary downfracture opened maxillary sinuses and the inner nose with the lower turbinates, which may still be covered by the preserved nasal floor mucosa.

Figs 10-1a and 10-1b Drawing of the skull layers during Le Fort I osteotomy in frontal section at the level of the first molars (red line) and in horizontal section at the level of the maxillary sinus. (Modified from Radlanski and Wesker,1 with permission)

First, the periosteum is loosened starting from the canine fossa distally to the region of the tuberosity (if possible without opening the buccal fat pad) and anteriorly to the nasal entrance (Fig 10-2a). This is followed by exposure of the infraorbital nerve at the foramen, exposure of the anterior nasal spine, release of the periosteum at the piriform aperture, and undermining and release of the mucosa of the two inferior nasal passages and the bony transition to the septum on both sides (Fig 10-2b).

Figs 10-2a to 10-2g (a) Glabellar circle measurement method: Determination of the midface height between the locked reference pin at the glabella and at the braces fixed dental wire. (b) After incision 4-mm cranial to the mucogingival border of the maxilla from region 16 to 26, free preparation of the canine fossa up to the infraorbital foramen and around the maxillary tuberosity is performed. (c)This is followed by osteotomy with the slow oscillating saw from the left tuberosity to the piriform aperture. (d) Loosening of the septum with the septal chisel above the nasal spine. (e) Overview of the operation side: loosened periosteum at the piriform aperture, at the anterior detached nasal spine, and at the lower inner nasal passages and complete Le Fort I osteotomy. (f and g) Transection of the lateral nasal walls with the left and right nasal chisels.

Figs 10-2h Retromaxillary osteotomy with the curved obverse chisel (see also Fig 10-7), and careful mobilization of the maxilla in regions of stable bone in the region of the tuberosity.

Horizontal osteotomy is performed with piezoelectric instruments or the longitudinal oscillating saw from the maxillary tuberosity to the lateral piriform aperture on both sides (Fig 10-2c). This is followed by release of the cartilaginous septum at the anterior nasal spine and sagittal separation of the entire anterior cartilaginous and posterior bony septum with the nasal chisel (Fig 10-2d

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Jan 19, 2024 | Posted by in Orthodontics | Comments Off on Le Fort I osteotomy

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