Epidemiological studies on the prevalence of marginal alveolar bone loss (ABL) in children and adolescent are often based on a single range of measurements from the cemento-enamel junction to the alveolar bone crest (CEJ-ABC distance). For individual diagnosis however, the clinician must take in consideration that the CEJ-ABC distances in the primary dentition increase with age, and significantly differ among sites. The purpose of the present study is to present the range and cumulative probabilities of the CEJ-ABC distances, at the primary cuspid-molar area, to be utilized for the individual diagnosis of ABL on bite wing radiographs of the primary dentition. In bite-wing radiographs from 316 children aged 4 to 12 years, the normal CEJ-ABC distances were measured in 0.1 mm increments at 2007 sites; mesial surfaces of the primary molars, and distal surfaces of the primary molars and cuspids. A positive correlation was found between the mean CEJ-ABC distance per patient and age. Most of the measurements were < 2 mm, and measurements between 2 to 3 mm were found, in low percentages after age 9, at the distal surfaces of teeth 53, 63, 54, 64, 73 and 83 and the mesial surfaces of teeth 54, 64.