RESUMEN
PURPOSE: The purpose of this study was to document the malocclusion and facial dysmorphology in patients with primary maxillary deficiency (PMD) and chronic obstructive nasal breathing before treatment and the outcomes after bimaxillary orthognathic, genioplasty, and intranasal surgery. MATERIALS AND METHODS: A retrospective cohort study of patients with PMD undergoing bimaxillary orthognathic, chin, and intranasal surgery was implemented. The predictor variables were grouped into demographic, anatomic, operative, and longitudinal follow-up categories. The primary outcome variables were the initial postoperative occlusion achieved (T2; 5 weeks postoperatively) and that maintained long-term (T3 or T4; >2 years after surgery). Six occlusion parameters were assessed: overjet, overbite, coincidence of dental midlines, Angle classification, and molar vertical and transverse positions. A second outcome variable was facial esthetic results. Photographs were analyzed to document 7 facial contour characteristics. RESULTS: Sixty-six patients met the inclusion criteria. Age at operation averaged 22 years (15 to 55 yr). The study included 18 women (27%). Most patients (57 of 66; 86%) achieved and maintained a favorable occlusion for each parameter studied long-term (mean, 5 yr). The need for a 3-segment Le Fort I was strongly associated with long-term posterior malocclusion. Facial dysmorphology before surgery included the appearance of a prominent chin (56%), flat labiomental fold (61%), prominent lower lip (88%), prominent nose (77%), sunken midface (100%), flat cheekbones (82%), and recessed upper lip (73%). Before surgery, 82% of patients exhibited at least 5 of the 7 key facial contour deformities. Correction of all 7 facial contour deformities was confirmed in 92% of patients in the long-term. In 8% of patients, an overly prominent-appearing chin persisted. CONCLUSION: Using orthognathic techniques, most patients with PMD achieved and maintained a corrected occlusion long-term. In unoperated patients, a "facial esthetic type" was identified. Bimaxillary orthognathic and chin surgery proved effective in correcting associated facial dysmorphology in most patients.
Asunto(s)
Oclusión Dental , Deformidades Dentofaciales/cirugía , Estética Dental , Maxilar/anomalías , Maxilar/cirugía , Adolescente , Adulto , Femenino , Mentoplastia , Humanos , Masculino , Maloclusión/cirugía , Persona de Mediana Edad , Obstrucción Nasal/cirugía , Procedimientos Quirúrgicos Ortognáticos , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Flying animals exhibit profound transformations in anatomy, physiology, and neural architecture. Although much is known about adaptations in the avian skeleton and musculature, less is known about neuroanatomy and motor unit integration for bird flight. Hummingbirds are among the most maneuverable and specialized of vertebrate fliers, and two unusual neuromuscular features have been previously reported: (1) the pectoralis major has a unique distribution pattern of motor end plates (MEPs) compared with all other birds and (2) electromyograms (EMGs) from the hummingbird's pectoral muscles, the pectoralis major and the supracoracoideus, show activation bursts composed of one or a few spikes that appear to have a very consistent pattern. Here, we place these findings in a broader context by comparing the MEPs, EMGs, and organization of the spinal motor neuron pools of flight muscles of Anna's hummingbird Calypte anna, zebra finches Taeniopygia guttata, and, for MEPs, several other species. The previously shown MEP pattern of the hummingbird pectoralis major is not shared with its closest taxonomic relative, the swift, and appears to be unique to hummingbirds. MEP arrangements in previously undocumented wing muscles show patterns that differ somewhat from other avian muscles. In the parallel-fibered strap muscles of the shoulder, MEP patterns appear to relate to muscle length, with the smallest muscles having fibers that span the entire muscle. MEP patterns in pennate distal wing muscles were the same regardless of size, with tightly clustered bands in the middle portion of the muscle, not evenly distributed bands over the muscle's entire length. Muscle activations were examined during slow forward flight in both species, during hovering in hummingbirds, and during slow ascents in zebra finches. The EMG bursts of a wing muscle, the pronator superficialis, were highly variable in peak number, size, and distribution across wingbeats for both species. In the pectoralis major, although the individual EMG bursts were much shorter in duration in hummingbirds relative to zebra finches, the variables describing the normalized amplitude and area of the activation bursts were otherwise indistinguishable between taxa during these flight modes. However, the degree of variation in the time intervals between EMG peaks was much lower in hummingbirds, which is a plausible explanation for the "patterned" EMG signals reported previously.