Normal level of alveolar crest below the CEJ of the adjacent teeth is:
ALVEOLAR CREST:
The gingival margin of the alveolar process that extends between the teeth is apparent on radiographs as a radiopaque line—the alveolar crest. The level of this bony crest is considered normal, when it is not more than 1.5 mm from the cementoenamel junction of the adjacent teeth.
Reference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 133
0.5-1 mm
1-1.5 mm
1.5-2.0 mm
1-2 mm