Hypodivergent facial growth pattern (Figure 20.5 ): Alternative terms are ‘ horizontal facial growth pattern, ’‘ low angle ’ patient (referring to the reduced mandibularplane angle), ‘ short face deformity ’ or ‘ short face syndrome.’ If the hypodivergent growth is the primary aetiology to a deep incisor overbite, the term ‘ skeletal deepbite ’ may be used. An element of vertical maxillary deficiency (VMD) often coincides with mild mandibular retrognathia, leading to a reduced lower anterior face height, a reduced mandibular plane angle and mandibular overclosure. Th is leads to an increased sagittal projection of the chin. 9 Such hypodivergent facial growth patterns will tend to be associated with an anterior pattern of mandibular growth rotation.
People who suffer from short face syndrom use to have
- a short lower third
- a retruded lower lip
- and a deep mentolabial fold (witch chin)
- a retruded chin in some cases
What surgeries can fix it:
Short face syndrom can be fixed through clockwisemaxillomandibular advancement (CW-Maxillomandibular Advancement). Both Maxilla and Mandibular get cut and moved forward/downward. The occusal plane change.
Figure 23-2 A 16-year-old girl arrived with her parents for surgical evaluation. She requested a reduction rhinoplasty and a chin implant. A diagnosis of maxillomandibular deficiency with a Class II excess overjet malocclusion was made. She agreed to a surgical and (redo) orthodontic approach. No extractions were carried out, and a degree of incisor proclination was tolerated. The patient’s surgery included maxillary Le Fort I osteotomy (horizontal advancement, vertical lengthening, and clockwise rotation) with interpositional grafting; sagittal split ramus osteotomies (horizontal advancement and clockwise rotation); and osseous genioplasty (vertical lengthening) with interpositional grafting. A, Frontal views in repose before and after treatment. B, Frontal views with smile before and after treatment. C, Oblique facial views before and after treatment. D, Profile views before and after treatment. E, Occlusal views before and after treatment. Only minimal change in the occlusion was required. F, Articulated dental casts that indicate analytic model planning. G, Lateral cephalometric radiographs before and after treatment.
After that the chin gets corrected aswell. In some cases the correction of the chin is even enough.
Case Study: This 35 year-old male wanted to improve his ‘weak’ chin. On examination he had both a vertical (8 to 10mms) and horizontal (5mms) chin deficiency. This made his lower face look short and gave his chin a short squat appearance. Computer imaging confirmed that a vertical chin lengthening procedure would improve his facial aesthetics.
Under general anesthesia, a horizontal chin osteotomy was done through an intraoral approach. The downfractured chin segment was vertically lengthened by 8mms and brought forward 5mms. It was held into position with a modified step titanium chin plate to create these dimensional changes. A hydroxyapatite block was shaped with a burr to create a wedge fit between the upper and lower chin segments. It was put in place after the chin segment had been stabilized by the plate. The mentalis muscle was reapproximated over the plate-bone-block chin construct and the mucosa closed.
After a chin osteotomy, considerable swelling ensued which took close to three weeks to return to a more normal appearance. The lower lip had some temporary numbness which was expected and the chin felt very stiff and unnatural for about a month after surgWhile the improvement in the chin’s appearance was immediate, critical analysis at 3 months after surgery showed the final result. He had complete return of all feeling and lower lip and mentalis muscle movement at that point. In seeing him at two years after surgery, the improvement was maintained as expected.It took a good six weeks until the chin felt more normal and a natural part of his face again.