Microgenia

Abstract: Microgenia or "small chin" is corrected by various techniques, such as insertion of an alloplastic implant, cartilage or bone grafting, or horizontal advancement osteotomy. Horizontal recession osteotomy is used in macrogenia. Particularly in a microgenic mandible, the mental foramen is unexpectedly nearer to the inferior border of the body. During sliding horizontal osteotomy of the mentum, the inferior alveolar nerve (IAN) and mental nerve are vulnerable to an injury. Thirty fresh hemimandibles were used for a study of the IAN. The IAN course was traced by serial sections at intervals of 5 mm. In 50 dry specimens the direction of the mandibular canal was evaluated by the photographs with a stick put into the mental foramen. The IAN in mandibular canal runs above the lower one-third of the mandibular body. The terminal mandibular canal locates at an average of 4.5 mm under the mental foramen, advances 5.0 mm anteriorly, loops, and ends at the foramen. The direction of the mandibular canal at the mental foramen was 39.4 degrees lateral, 67.2 degrees superior, and 80.2 degrees posterior. It is advisable for surgeons to keep the level of sliding osteotomy of the mentum at least 4.5 mm below the mental foramen to spare the IAN.

Abstract: This retrospective study was undertaken in order to compare the objective and subjective outcomes of the osteoplastic and alloplastic genioplasties. Of the 76 patients that underwent augmentation or advancement genioplasty, 34 were subjects of osteoplastic genioplasty and 42 received implants. Twenty seven of 34 patients who underwent osteotomy and 32 of 42 patients whose chins were augmented with an implant responded to the questionnaires. The results revealed that both groups were highly satisfied, with a slightly higher satisfaction rate for those who underwent osteotomy. The morbidity was the same for both procedures. However, the soft tissue response was more predictable for the osteoplastic genioplasty. The cervicomental angle improved more with the osteoplastic genioplasty. Based on our experience and conclusions from this study, we recommend the osteoplastic genioplasty for every patient. However, for patients in the older age group, particularly those with a small degree of microgenia, alloplastic genioplastic can be justified.

Abstract: Two sisters with a complex clinical pattern, including microcephaly, microgenia, defects of skin pigmentation, anal stenosis/atresia, and combined immunodeficiency together with spontaneous chromosomal instability and cellular hypersensitivity to X-rays and bleomycin are described. Complementation studies on heterokaryons proved that the underlying genetic defect is non-allelic with that of patients with ataxia telangiectasia (complementation groups AB-E) and the Nijmegen breakage syndrome, but identical with the case described by Conley et al. (1986).

Abstract: A visually pleasing chin is an important component of facial harmony. This study was undertaken to introduce a practical classification of chin dysmorphology, which can be used to guide the surgeon toward the appropriate surgical approach to chin repair. Analysis of life-size photography, based on standard anthropometric measurements, was completed on 2,879 patients from 1981 to 1991. Six hundred eighty-four patients were noted to have normal occlusion with some form of chin deformity. Analysis of this group of patients identified seven categories of chin dysmorphism: Class I, macrogenia (n = 170, 24.9%); Class II, microgenia (n = 435, 63.6%); Class III, combination of macrogenia in one direction and microgenia in the other direction (n = 54, 7.9%); Class IV, asymmetry (n = 4, 0.6%); Class V, soft tissue ptosis ("witch's chin") (n = 13, 1.9%); Class VI, pseudomacrogenia (normal skeletal symphysis menti with excess soft tissue covering) (n = 5, 0.73%); and Class VII, pseudomicrogenia (long-face deformity producing clockwise rotation of the normal mandible) (n = 3, 0.4%). Having diagnosed the dysmorphism, logical surgical recommendations for lower face improvement were postulated. Only patients with Class II chin deformity can be corrected with augmentation. Classes I, III, and IV require an osteotomy of the chin. Classes V and VI benefit from soft tissue correction. Class VII deformity can be corrected with a maxillary osteotomy.