Virtual Digital Articulation Versus Hand-articulation Accuracy for Occlusal Registration in Orthognathic Surgery

Overview

Conventionally, orthognathic occlusal planning is performed by physically articulating the study models until a well interdigitated occlusion is achieved. this is undertaken in conjunction with the analysis of the face and jaw bones for surgical planning. Computer-assisted planning now allows digital planning of orthognathic surgery, including assessment of the quality of the final occlusion and printing of the guiding occlusal wafers. This can be achieved through the replacement of the defective images of the dentition produced by the cone beam computed tomography (CBCT) scan with accurate digital images of the study models, captured using CBCT or laser scanning

The determination of an ideal dental occlusion is a vital step in planning orthognathic surgery. Conventionally, a dental occlusion is determined using model surgery based on two dimensional cephalometric planning for the movement of maxillary and mandibular segments. Later, acrylic surgical splints were fabricated in the articulator and used in operating rooms to reposition jaw bones. This conventional method is well established, widely used, and inexpensive. However, its main disadvantages are that patients experience discomfort during the impression procedure, and making dental models and performing model surgery are time consuming. In addition, there is a need for storing dental casts, and errors may occur during this procedure. Computer-aided simulation surgery and three-dimensional planning have become popular. Nadjmi et al. proposed an experimental method for virtual occlusions and demonstrated that the mean distance between their conventional and virtual manual occlusion was small. Adolphs et al. scanned a dental cast and aligned the tooth image for a virtual occlusion by using a software program and reported no difference between the virtual and traditional splint when fitted to a patient's dentition. Wu et al. proposed an experimental haptic simulation framework to determine the virtual occlusion in digital models and showed that the translation and angular deviation of virtual results were smaller compared with the benchmark. However, because the conventional dental impression and model are still required in the computer-aided system and the occlusion setup is determined by the dental model, it cannot be described as fully digital three dimensional planning. Intraoral digital scanning is an innovative dental technology that has advanced the field of prosthodontics and orthodontics. This technique has been introduced as an alternative to the conventional method for scanning patients' dentition and has become a convenient method for digital impression and model fabrication.The scans can be imported to a software program for planning orthodontic treatment. However, the use of intraoral scanning for the digital setup of the final dental occlusion in three-dimensional orthognathic surgery planning has not yet been reported.