The project was approved by the Ethics Committee for Research Involving Human Beings of UEM (protocol 2.336.453). The inclusión criteria used in this study were the absence of positive or negative bubbles in the plaster models and presence of teeth in perfect condition without anatomical defects. This retrospective study used plaster models of 40 patients of both sexes, who underwent orthognathic surgery and made orthodontic-surgical treatment in the clinic of the Dentistry Department of State University of Maringá (UEM). So, the purpose of this study was to assess the accuracy and the degree of magnification of images of plaster models obtained through 3D scanner and CBCT, comparing them with the digital caliper, which is considered the gold standard. Previous studies comparing the accuracy between linear measurements in plaster models and digital models made from scanned dental impressions or plaster models found mean differences between 0.04 and 0.62 mm 15, 17, 18.
In addition, these models may be easily shared via Internet, and copies of these digital models can be generated at no cost 15, 16.ĭigital models have been shown to be a valid tool for VSP and to perform simple diagnostic measurements, such as the size of teeth, arc width, horizontal and vertical trespasses, arc length and Bolton ratio 16. Digital models may be stored electronically, which significantly reduces the storage space and the risk of physical damage. Once obtained, digital models offer several advantages over plaster models. However, it cannot be used to perform virtual processing of digital models, so, it is required to convert it into another format named STL (Standard Tessellation Language), which is the industry standard for rapid prototyping 14. Then, the file to be generated from scanning is saved in DICOM format (Digital Imaging and Communications in Medicine). Such scanning of plaster models may be made through 3D scanner or CBCT 13. When scanning was introduced in the world of orthognathic orthodontics/surgery, digital dental models could replace the traditional plaster ones.
Therefore, the dental part in the tomographic image needs to be replaced with another modality of image to produce an accurate craniodental model 9, 10, 11, 12. The quality of the image obtained through CBCT is insufficient for an accurate representation of the teeth. Although cone-beam computed tomography (CBCT) images might provide excellent skeletal representations, it is not possible to obtain detailed dental and interocclusal data 7, 8. Furthermore, it allows clinicians to establish accurate treatment plans 5, 6.
The use of 3D images in the maxillofacial area provides accurate diagnostic Information based on an accurate visualization of anatomical structures 3, 4. In addition, it is used as a communication tool among the orthodontist, the oral and maxillofacial surgeon and the patient, in order to determine the amount and the direction of the surgical movement of hard and soft tissues, as well as assisting in pre- and post-operative orthodontic treatment 2. In a simple way, 3D VSP is the processes that uses clinical data, image testing, and plaster models of dental arches and clinical photos of the patient to simulate an orthognathic surgery in a virtual environment and then transfer the planned movements to the surgical act. Currently, advances in computer technology provide dental surgeons with the ability to integrate all relevant information of the three-dimensional virtual surgical planning (3D VSP) into a single model of multi-modality imaging, whose clinical advantage is to study complex asymmetric deformities within the orthognathic surgery 1.