Masticatory muscle right-left differences in controls and hemifacial microsomia patients.

One aim of this study was to assess right-left differences in the volume of masticatory muscles in controls so as to be able to distinguish between normal variations and pathological differences. The other aim was to compare the masticatory muscle volume of the nonaffected side of hemifacial microsomia patients with the smaller side of controls so as to test the compensation hypothesis. The study group consisted of 39 children with hemifacial microsomia and the control group of 52 children. Computed tomography scans were made using a Philips Tomoscan 350 and a Pro Speed S Fast Spiral General Electric scanner. The normal right-left differences in volume of the masticatory muscle of the controls, calculated as a percentage of the total, demonstrated small mean differences of 2.57% to 2.88% (SD:1.98-2.74). For hemifacial microsomia patients, the relative difference was about 10 times the difference for controls. For controls, the averages of the right-left differences (%) were all below the generally accepted SEM of 4%. Testing the compensation hypothesis of all effects, only the age effect was multivariately significant (P < 0.001). No overcompensation of the masticatory muscles of the nonaffected side of hemifacial microsomia patients could be demonstrated.

Perception of symmetry in the face.

One purpose of this study was to assess the perception of (a)symmetry of the face by professionals, lay persons, and sculptors using the ratio estimation scale technique. The other purpose was to compare the perceptions of the faces of patients with those of the controls. Three groups of examiners were involved in this study: lay persons (n = 37), professionals (5 orthodontists and 11 surgeons, n = 16), and sculptors (n = 22). The total number of examiners was 75. All groups agreed on the ordering of the patients according to the severity of the affliction. The stage of asymmetry by group identity interaction effect (lay persons, professionals, and sculptors) was significant (P = 0.004). The between-examiner consensus was high for the original asymmetrical photograph, but the groups diverged further and further over the next steps. The subject identity by stage of asymmetry interaction effect was significant (P = 0.001), whereas the examiner's main effect was not. For all patients, each step resulted in a smaller need for treatment. A need for treatment was not found for any of the control subjects, with 1.5 being the highest need for treatment score for controls. The subject identity effect (patient/control) was significant (P < 0.001). Even at step 5 (the reconstructed symmetrical photograph), all patients were perceived to have an inferior appearance to that of control subjects. It is possible to obtain reliable assessment using the ratio estimation scale technique. Professionals, lay persons, and sculptors have different perceptions of the degree of asymmetry but not of the need for treatment. All patients were scored as asymmetrical compared with controls. Asymmetry of the patients was obvious for all the examiners.

Longitudinal results of mandibular distraction osteogenesis in hemifacial microsomia.

The aim of this study was to evaluate mandibular distraction therapy by three-dimensional (3-D) computed tomography (CT) imaging so as to be able to improve the treatment results. The study group consisted of eight children (3 male and 5 female) with hemifacial microsomia. For each child, CT scans of the head were available (Pro Speed S Fast Spiral scanner; General Electric). Longitudinal measurements of the mandible, bony and soft tissue 3-D reconstructions, and masticatory muscles were demonstrated. Three-dimensional CT scans provide important data concerning the results of mandibular distraction therapy and should be used in treatment evaluation. In some patients and for some muscles only, a small increase in the volume of the affected side of the masticatory muscles in comparison to the normal side was found 3 years after mandibular distraction. In around 50% of the cases, there seems to be a relapse occurring 1 year after distraction osteogenesis, and this relapse has a progressive character when seen 3 years after distraction osteogenesis in comparison to 15 weeks after distraction osteogenesis.