Feature Article

Basic components of the conventional prosthodontic diagnostic set-up workflow include dental cast models, full-mouth two-dimensional digital photographs, as well as selected intra- and extra-oral radiographs. This set-up provides a limited two-dimensional representation of the maxillofacial region and it fails to depict the patient in full three dimensions, thereby limiting diagnosis and treatment planning. Novel three-dimensional (3D) imaging technologies such as digital intra-oral scanning and cone beam computed tomography (CBCT) are becoming increasingly available in the dental office. However, these technologies are limited in capturing the dentition and alveolar bone due to little regard to the soft tissue profile. Facial scanning is a rapidly evolving technology with a wide range of applications in the fields of biomedical engineering, industrial design and 3D animations. In dental medicine, the technology has its roots in orthodontics and orthognathic surgery and provides the basis for comprehensive 3D mapping of the face for treatment planning and follow-up purposes. Recently, there has been increasing interest in applying facial scanning technology in prosthodontics and implant dentistry. The aim of this review is to shed some light on the evolution of facial scanning technology and to demonstrate the scanning principles, while providing some perspective on potential applications in prosthetic dentistry. An attempt is also made to discuss the accuracy and limitations of this novel technology, and to examine future trends.

Introduction and background information

In recent years, the immense technical advancements in dental medicine have ushered modern clinical practice into a new era. Computer-based techniques to capture and analyze the facial structures for pre-operative diagnostics and treatment planning are becoming ubiquitous. There has been increasing availability of rapid, compact, in-office digital intraoral (DIO) and cone beam computed tomography (CBCT) scanners coupled with an expanding armamentarium of software tools to visualize, analyze and merge the datasets generated by these scanners in daily practice. For the first time in dental medicine, the concept of designing a ‘virtual patient replica’ could become a reality. Three-dimensional (3D) imaging of the dentition, alveolar bone and covering soft tissues constitute what can be described as ‘the prosthetic diagnostic triad’. Acquiring information on all three aspects would form the basis for a comprehensive treatment plan. However, in recent years there has been a disproportional emphasis in prosthetic dentistry on capturing only two elements of this triad, namely teeth and bone, with very little regard given to the external profile of the patient. Yet, with regard to facial esthetics, imaging of the soft tissue profile is of utmost relevance as it is the facial entity most readily visible (Rangel et al. 2008). A thorough and comprehensive evaluation of the facial soft tissue profile would undoubtedly benefit pre-operative diagnostics, and could thereby result in more predictable treatment and optimal esthetic results.

In the fields of orthodontics and orthognathic maxillofacial surgery there has been burgeoning interest in applying facial scanning technology to plan advanced and complex cases. Numerous articles and reviews have been published regarding technology applications, accuracy assessment and ongoing developments in those fields (Hajeer et al. 2004, Verhoeven et al. 2013). The purpose of this review is to examine the evolution of 3D facial scanning technology, the various technologies present, the available devices, applications, constraints and future perspectives specifically in the fields of prosthodontics and implant dentistry.