Periodontal bone heights (i.e., the distances from the cement–enamel junction [CEJ] to the alveolar bone crest [ABC]) were measured in defleshed maxillae under a Nikon SMZ800 microscope using a 40x objective. Briefly, images of the maxillae were captured using a Nikon Digital Sight DS-U3 camera controller and CEJ–ABC distances were measured at 14 predetermined sites [41 (link)] or, in the case of split-mouth experiments, at 6 predetermined sites [42 (link)] using NIS-Elements software (Nikon Instruments). For calculating change in bone levels (e.g., relative bone loss in CD18−/− mice versus WT controls), the 14-site (or 6-site) total CEJ-ABC distance for each mouse was subtracted from the mean CEJ-ABC distance of control mice. The results are presented in mm; negative values indicate bone loss and positive values indicate bone gain relative to controls. In experiments involving split-mouth design (treatments with drug vs. control in opposite halves of the maxilla), the data shown involve measurements for each hemi-maxilla.