PAX9 and tooth agenesis: For instance, patients with tooth agenesis caused by Wnt10B mutation may also have microdontia and taurodontism.75 In patients with tooth agenesis caused by Pax9 mutations, the middle incisors in the upper jaw are susceptible to microdontia,76 and regional odontodysplasia may also occur.77 In addition, tooth agenesis may affect the oral arch length, jaw position and craniofacial morphological features.78,79 Therefore, imaging is necessary for early diagnosis, prompt intervention80 and multidisciplinary treatment to maintain the aesthetic and functional features of teeth.