1 Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
2 Faculty of Dentistry, The University of Hong Kong, Hong Kong, China; Department of Computer Science, Hong Kong Chu Hai College, Hong Kong, China.
3 Faculty of Dentistry, The University of Hong Kong, Hong Kong, China; Musketeers Foundation Institute of Data Science, The University of Hong Kong, Hong Kong, China. Electronic address: retlaw@hku.hk.