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Dentofacial (dentoskeletal) deformities are characterized by an abnormal position of the maxilla and/or mandible and associated teeth that affect jaw function and facial aesthetics. These deformities are as follows ( Fig. 22.1 ):
Class I—normal skeletal pattern, maxilla and mandible in an orthognathic relationship
Occlusal relationships are characterized by the mesiobuccal cusp of the maxillary first molar occluding with the mesiobuccal groove of the mandibular first molar; the maxillary canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular first premolar.
Class II—skeletal deformity characterized by a deficient mandible
Class III—skeletal deformity characterized by a prognathic mandible
Class II and III occlusal relationships are characterized by the mesiobuccal cusps of the maxillary first molar being mesial and distal to the buccal groove of the mandibular first molar, respectively, as well as the distal surface of the mandibular canine being distal and mesial to the mesial surface of the maxillary canine, respectively.
In addition to anteroposterior jaw discrepancies, there are transverse jaw discrepancies, open bite or deep bite discrepancies, vertical (excess or deficient) deformities, and chin deformities—retrusive (retrogenia) or protrusive (progenia).
Dentofacial deformities of the maxilla, mandible, and chin include overgrowth (hyperplasia), undergrowth (hypoplasia), and asymmetries. Facial aesthetics are compromised by the abnormal position of the maxilla, mandible, and chin.
Patients may appear to have an upper or lower jaw or chin that is too large or too small, which manifests within the dentition as a malocclusion (e.g., class I, II, III). There may be a lip incompetence, mentalis strain, gummy smile, underbite, overbite, poor neck-chin-throat morphology, sagging skin, submental redundancy, lack of malar projection, scleral show, ptotic nasal tip, everted lower lip, thin upper lip, and other facial aesthetic problems.
A thorough cephalometric analysis assists the clinical and radiographic diagnostic evaluation and treatment of the malocclusion and skeletal deformity. The operative plan should be clinically driven with the aid of three-dimensional treatment planning and virtual surgical planning (VSP) considering functional and aesthetic concerns ( Fig. 22.2 ).
Surgical therapy is aimed at the correction of the specific individual patient deformity, with correction of the malocclusion, functional deficiency, and unaesthetic appearance. Surgical procedures include a maxillary Le Fort osteotomy ( Fig. 22.3 ), malar augmentation, mandibular sagittal split osteotomy ( Fig. 22.4 ), vertical ramus osteotomy, various other forms of ramus osteotomies (e.g., inverted L osteotomy), chin genioplasty procedures ( Fig. 22.5 ), and malar augmentation ( Fig. 22.6 ).
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