Walter Y H Lam1, Richard T C Hsung2, Leo Y Y Cheng3, Edmond H N Pow4. 1. Prosthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region, China. 2. School of Information Engineering, Guangdong University of Technology, Guangdong, China. 3. Dental Technology, Prosthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region,China. 4. Prosthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region, China. Electronic address: ehnpow@hku.hk.
Abstract
OBJECTIVES: Tooth shade is crucial to patient satisfaction in aesthetic dentistry. Two-dimensional (2D) clinical photographs have been widely used to record patients' tooth shade for creation of beautiful smile. However, in the digital workflow, 3D virtual teeth models in open file format contain only mesh information with no colour. This paper describes the mapping of colour information from the intraoral photographs onto the virtual teeth model. METHODS: Intraoral photographs of occlusal and buccal views were taken using digital single lens reflex (SLR) camera with macro lens and ring flash. Photographs were calibrated for its colour and white balance. Virtual models were generated by scanning teeth/stone casts using an intraoral/model scanner. Intraoral photographs were mapped onto the virtual model using the image-to-geometry registration method by locating corresponding feature points in the 2D and 3D images. RESULTS: Virtual teeth models of dentate (with and without crowding) and partially dentate patients were mapped with intraoral photographs. The resultant models are open file format and can be viewed and manipulated in dental or generic CAD/CAM software. Moreover, RGB (Red Green Blue) colour information and error of registration can be retrieved. CONCLUSION: Image-to-geometry registration allows mapping of colour information in the 2D intraoral photographs on 3D virtual teeth models. The proposed method is applicable across scanning systems and the coloured model can be generated from stone casts and intraoral photographs. CLINICAL SIGNIFICANCE: Virtual teeth model with colour information facilitates shade matching and creation of beautiful smile.
OBJECTIVES: Tooth shade is crucial to patient satisfaction in aesthetic dentistry. Two-dimensional (2D) clinical photographs have been widely used to record patients' tooth shade for creation of beautiful smile. However, in the digital workflow, 3D virtual teeth models in open file format contain only mesh information with no colour. This paper describes the mapping of colour information from the intraoral photographs onto the virtual teeth model. METHODS: Intraoral photographs of occlusal and buccal views were taken using digital single lens reflex (SLR) camera with macro lens and ring flash. Photographs were calibrated for its colour and white balance. Virtual models were generated by scanning teeth/stone casts using an intraoral/model scanner. Intraoral photographs were mapped onto the virtual model using the image-to-geometry registration method by locating corresponding feature points in the 2D and 3D images. RESULTS: Virtual teeth models of dentate (with and without crowding) and partially dentate patients were mapped with intraoral photographs. The resultant models are open file format and can be viewed and manipulated in dental or generic CAD/CAM software. Moreover, RGB (Red Green Blue) colour information and error of registration can be retrieved. CONCLUSION: Image-to-geometry registration allows mapping of colour information in the 2D intraoral photographs on 3D virtual teeth models. The proposed method is applicable across scanning systems and the coloured model can be generated from stone casts and intraoral photographs. CLINICAL SIGNIFICANCE: Virtual teeth model with colour information facilitates shade matching and creation of beautiful smile.