Figure 1

Functional inactivation of Enpp1 leads to the formation of cervical cementum vulnerable to resorption. (a) The surface structure of the distal root of the mandibular first molar at P84 through SEM analysis (Top). Tissue sections of the mandibular first molar from Enpp1^asj and the control mice at P84 were stained with H-E (Middle). TRAP staining was performed with tissue sections of the mandibular first molar at P84 (Bottom). The images of cervical cementum were taken within a site 500 μm apical (one third of total distal root length) from the cemento–enamel junction (CEJ) of the mandibular first molar. (b) Molecular changes of Npp1 in the cervical cementum were detected by IHC staining with tissue sections of the mandibular first molar at P28 (Top). The TRAP-positive area of cervical cementum and faced alveolar bone were exhibited with tissue sections of the mandibular first molar at P28 (Middle) and P56 (Bottom). Black arrow heads indicate Npp1-positive and TRAP-negative cervical cementum of WT. Yellow arrow heads indicate resorption lacunae of the thickened cervical cementum layer of Enpp1^asj mice. CEJ, cemento-enamel junction; D, dentin; PDL, periodontal ligament; C, cementum; EC, ectopic cementum; AB, alveolar bone. Scale bars are indicated. (c) The TRAP-positive area of cervical cementum and faced alveolar bone were analyzed using tissue sections at P28 and P56 after TRAP staining (n = 3). Significance was assigned with p-values as indicated in the graph.