Simplified protocol for tomographic evaluation of mandibular asymmetry

Aim: Facial asymmetries occur near and even above 20% of the patients who attend consultation of Orthodontics. They are the result of the interaction of multiple factors that influence the growth and development, causing discrepancies in size and position between various structures that make up the complex facial skull that depending on the severity and the potential for adaptation of the individual may compromise your facial balance and function. The etiology is believed to be related to congenital, developmental, or acquired factors. Genetic and trauma-related asymmetries may involve muscles, produce excessive unilateral growth, or adversely affect mandible development. Genetic and trauma-related asymmetries may involve muscles, produce excessive unilateral growth, or adversely affect mandible development. The growth of the skull, maxilla, and mandible are closely related. If growth is altered in one of these areas, the asymmetric growth and development of part of the craniofacial skeleton may result in a chin deviated from the mandibular midline. The advent of computed tomography has greatly reduced magnifcation errors from geometric distortions that are common in conventional radiographs. The three-dimensional software (3D) recently introduced allows 3D reconstruction and the multiplanar images obtained from the tomography allow the quantitative measurement of the maxillofacial complex, useful to understand the asymmetric structures involved. The aim of the present work was developing a simplifed protocol on Cone Beam tomography (CBCT) or computed tomography (CT) images, for evaluation of the morphology and dimensions of bone structures involved in the etiology of mandibular asymmetry, for better diagnosis and treatment planning. Methods: Based on the review of the literature is349 Abstracts of poster presentations © ARIESDUE June 2019; 11(2) elaborated a descriptive protocol for evaluation of facial asymmetry on CBCT or CT. Different softwares are applied: volumetric reconstructions in 3D, multiplanar and 2D radiological images. Three reference lines were defned to asses facial asymmetry (vertical, horizontal and axial), from which the structures will be studied; anatomical landmarks are located, and linear and angular measurements are obtained. The asymmetry indices of the bilateral landmarks were calculated. Results: The measurements were recorded in columns showing the right and the left values, respectively and the difference for each pair was recorded in a third column. All measured values were recorded on a chart, and the differences between the right and left side were analyzed. The asymmetry index of each landmark is summarized. Conclusion: The morphological study of the mandibles structures on CBCT or CT and their interpretation is very important for the orthodontic and surgical diagnostic and treatment planning phases as well as in the postoperative follow-up. The protocol proposed in this work simplifes the identifcation of structures involved in the facial asymmetry, as well as its severity, facilitates the diagnosis and the multidisciplinary management