RESUMEN
PURPOSE: Transoral placement of bicortical screws is a rigid fixation method in orthognathic surgery that is used less often than transbuccal placement. The aim of this study was to examine the postoperative outcome of transoral bicortical screw insertion during orthognathic surgery and to compare it with the more common transbuccal fixation technique. MATERIALS AND METHODS: A retrospective cohort study was conducted. Clinical files of orthognathic surgery patients operated on from January 2010 through December 2012 were reviewed. Screw insertion approach (transoral vs transbuccal) was examined as a predictive variable for postoperative complications (hardware removal and infection). Type of surgery, fibrin sealant, preoperative third molar removal, and patient age and gender were analyzed as potential risk factors. Descriptive and bivariate statistics and regression analyses were performed. RESULTS: Of the 606 patients whose cases were reviewed, 509 patients (185 men; mean age, 26.3 ± 11.1 yr) met the inclusion criteria. Most presented with a Class II malocclusion (84.5%). A transbuccal approach was used in 27.5% of cases, leading to a screw-related infection of 6.3%. Patients treated with a transoral technique (72.5%) had fewer infections (3.5%), but this was not statistically relevant. Screw removal was indicated in 3.3% of patients. Screw placement using the transoral and transbuccal approaches was performed in 3.0 and 4.2% of patients, respectively. Infection and screw removal rates did not differ significantly between fixation techniques (P = .16 and P = .49, respectively). CONCLUSION: The present findings showed an overall low rate of screw removal and infection secondary to bicortical screw insertion during orthognathic surgery. The postoperative outcome was similar for the transoral and transbuccal approaches.
Asunto(s)
Tornillos Óseos , Maloclusión de Angle Clase III/cirugía , Maloclusión Clase II de Angle/cirugía , Osteotomía Mandibular/métodos , Osteotomía Sagital de Rama Mandibular/métodos , Adolescente , Adulto , Remoción de Dispositivos/estadística & datos numéricos , Estudios de Factibilidad , Femenino , Estudios de Seguimiento , Humanos , Modelos Logísticos , Masculino , Osteotomía Mandibular/instrumentación , Persona de Mediana Edad , Osteotomía Sagital de Rama Mandibular/instrumentación , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento , Adulto JovenRESUMEN
The aim of this study was to present a new approach to acquire a three-dimensional virtual skull model appropriate for orthognathic surgery planning without the use of plaster dental models and without deformation of the facial soft-tissue mask. A "triple" cone-beam computed tomography (CBCT) scan procedure with triple voxel-based rigid registration was evaluated and validated on 10 orthognathic patients. First, the patient was scanned vertically with a wax bite wafer in place (CBCT scan No1). Second, a limited dose scan of the patient with a Triple Tray AlgiNot impression in place was carried out (CBCT scan No2). Finally, a high-resolution scan of the Triple Tray AlgiNot impression was done (CBCT scan No3). Sequential and semiautomatic triple voxel-based rigid registration (RNo1-RNo3) was performed to augment the patient's skull model with accurate occlusal and intercuspidation data (Maxilim, version 2.1.1., Medicim NV, Mechelen, Belgium). All registrations were based on the Maximisation of Mutual Information registration algorithm. Because the accuracy and stability of the voxel-based registration (RNo1) between the Triple Tray AlgiNot impression scan and the limited low-dose patient scan were not known, this particular registration step needed to be validated. The accuracy of registration was measured on a synthetic skull and showed to be highly accurate. A volume overlap of 98.1% was found for registered impression scan No1. The mean distance between registered impression scan No1 and registered impression scan No2 was 0.08 +/- 0.03 mm (range, 0.04-0.11 mm). As far as the stability of registration was concerned, successful registration with a stable optimal position was obtained with a maximum variability of less than 0.1 mm. The results of this study showed that semiautomatic sequential triple voxel-based rigid registration of the triple CBCT scans augmented the 3-D virtual skull model with detailed occlusal and intercuspidation data in a highly accurate and robust way. The method is therefore appropriate and valid for 3-D virtual orthognathic surgery planning in the clinical routine.
Asunto(s)
Tomografía Computarizada de Haz Cónico/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Modelos Anatómicos , Procedimientos Quirúrgicos Ortognáticos , Planificación de Atención al Paciente , Interfaz Usuario-Computador , Algoritmos , Relación Céntrica , Materiales de Impresión Dental , Técnica de Impresión Dental/instrumentación , Oclusión Dental , Humanos , Registro de la Relación Maxilomandibular/instrumentación , Registro de la Relación Maxilomandibular/métodos , Proyectos Piloto , Siliconas , Dimensión VerticalRESUMEN
A detailed visualization of the interocclusal relationship is essential in a three-dimensional virtual planning setup for orthognathic and facial orthomorphic surgery. The purpose of this study was to introduce and evaluate the use of a wax bite wafer in combination with a double computed tomography (CT) scan procedure to augment the three-dimensional virtual model of the skull with a detailed dental surface. A total of 10 orthognathic patients were scanned after a standardized multislice CT scanning protocol with dose reduction with their wax bite wafer in place. Afterward, the impressions of the upper and lower arches and the wax bite wafer were scanned for each patient separately using a high-resolution standardized multislice CT scanning protocol. Accurate fitting of the virtual impressions on the wax bite wafer was done with surface matching using iterative closest points. Consecutively, automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model (Maxilim, version 2.0; Medicim NV, St-Niklaas, Belgium). Probability error histograms showed errors of < or =0.16 mm (25% percentile), < or =0.31 mm (50% percentile), and < or =0.92 (90% percentile) for iterative closest point surface matching. The mean registration error for automatic point-based registration was 0.17 +/- 0.07 mm (range, 0.12-0.22 mm). The combination of the wax bite wafer with the double CT scan procedure allowed for the setup of an accurate three-dimensional virtual augmented model of the skull with detailed dental surface. However, from a clinical workload, data handling, and computational point of view, this method is too time-consuming to be introduced in the clinical routine.
Asunto(s)
Materiales Dentales , Oclusión Dental , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Registro de la Relación Maxilomandibular/instrumentación , Modelos Anatómicos , Cráneo/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Interfaz Usuario-Computador , Ceras , Arco Dental/diagnóstico por imagen , Técnica de Impresión Dental , Oclusión Dental Céntrica , Humanos , Procedimientos Quirúrgicos Ortognáticos , Planificación de Atención al Paciente , Dosis de RadiaciónRESUMEN
INTRODUCTION: The transpalatal distractor is a bone-borne device that eliminates negative orthodontic effects during and after maxillary expansion. It produces virtually parallel expansion in the coronal plane. Orthodontic appliances can be installed at an earlier date than when tooth-borne expanders are used. Our aim was to improve the technique by reviewing the difficulties encountered during applications in the past. PATIENTS AND METHODS: The files of 57 patients were analyzed for problems (difficulties requiring surgical intervention), obstacles (difficulties requiring surgical intervention but not interfering with the result), and complications (difficulties not resolved at the end of the treatment). RESULTS: Twenty-nine difficulties occurred. In 25 cases they were considered to be a 'problem'. Nine problems were surgery related and 16 problems were related to the distraction device itself (14 episodes of loosening of the module, two instances of loss of one osteosynthesis screw). 'Obstacles' occurred in three cases, i.e. loosening of an abutment plate. There was only one 'complication': unilateral infraorbital hyposensibility in a case of a high level corticotomy. CONCLUSION: The expansion goal was achieved in all patients. Loosening of the module proved to be the major cause of discomfort. The incidence of difficulties has lead to a change in the design of the hardware and in the surgical protocol.