[Facial expression of the vertical dimension before and after orthognathic surgery]

The dynamic analysis of faces of the patients asking for a restoration for an aesthetic injury with a combined orthodontical-surgical treatment requires, besides a static morphological study: with photographs an cephalometric tracings; the study of their facial expression. In order to find out a method of classification of the units of expressive facial behavior, the mobility of the face is studied through the coding of the facial activity by P. EKMAN and W. FRIESEN i.e. the F.A.C.S.: Facial Action Coding System: From the video-recordings of faces and their photographic versions obtained after a pause on the video recorder, these authors have improvised a technic based on the visual observation of the anatomical basis of the movement in connection with facial expression and their description through minimal anatomical action units or A.U. These minimal units of behaviour combine to form mimics. Thanks to the F.A.C.S., the facial mimic of 18 patients before and after orthognatic surgery, and of six samples without dentofacial deformations has been studied. 18,844 AU have been observed, among 6,278 mimics made all together, with 604 different types. A classification of the mimics made by everyone and repeated in time has enabled us to establish a king of "norm" related to expression, allowing us some comparisons with expression of deformed patients. On one hand, for all of the patients examined, we have observed the mimics of the patients after surgery were more identical to the mimics of the samples. On the other hand, some differences have been distinguished concerning the changes of expressivity after surgery depending on the type of morphology before surgery: thus, rather a normal activity of the shrinking of the orbicularis oris has been observed, as well as the buccinator, among the open bites that had been operated on; and the activity of the uppe lip deriving from the "levator Labu Superious Caput infra orbitalis" has become more normal, and rather a normal activity of the lower lip deriving from mentalis, among the operated deep-bites. These results are akin to the clinical observations and suggest that the F.A.C.S. will be able to provide a coding for the study of facial expression.