Figure 2.

Altered periodontium in Enpp1 mutant mice. (A, B) Two-dimensional micro–computed tomography (CT) reconstructions of wild-type (WT) and Enpp1^asj mouse mandibles highlighting the mandibular first molar (M1) in sagittal, coronal (buccal-lingual), and transverse planes (respectively, left to right). Acellular cementum (AC) is highlighted in yellow and cellular cementum (CCM) is highlighted in blue. Note the dramatically expanded AC in Enpp1^asj mice versus WT, although the periodontal ligament (PDL) space is maintained between M1 and alveolar bone (AB). (C, D) Three-dimensional micro-CT reconstructions of WT and Enpp1^asj mandibular molars separated from alveolar bone socket. Segmented PDL space around molar roots is highlighted light blue. (E) Overlay of PDL thickness from M1 mesial roots shows that Enpp1^asj PDL (red) is maintained and expanded over WT PDL (blue). (F) Alveolar bone volume shows no significant differences between WT and Enpp1^asj mice. (G) Basal bone volume is significantly increased (*P = 0.01) in Enpp1^asj versus WT mice. (H) Enpp1^asj mice display a significant (*P = 0.01) increase in PDL volume around the first molar. (I) Surface area (SA) of PDL interface with bone and tooth is significantly (**P = 0.002) increased in Enpp1^asj versus WT mice. Using a 50-slice (300-µm) region of interest midway down the mesial molar root, Enpp1^asj mice display (J) significantly increased PDL thickness (**P = 0.009) and (K) significantly increased PDL-bone/tooth SA (***P = 0.0001) compared to WT controls. Separating the bone and tooth sides of the PDL interface confirms (L) significantly increased bone-PDL surface SA (**P = 0.004) and (M) cementum-PDL SA (***P = 0.0004) compared to WT controls.