The alveolar bone height of the primary and first permanent molars in healthy 6- to 9-year-old Jordanian children GHAIDA AL JAMAL 1 , OLA AL-BATAYNEH 2 & DIMA HAMAMY 2 1 Department of Oral Medicine and Oral Surgery, and 2 Department of Preventive Dentistry, Faculty of Dentistry, Jordan University of Science & Technology, Irbid, Jordan International Journal of Paediatric Dentistry 2011; 21: 151– 159 Aim. To establish a threshold cemantoenamel junction (CEJ)–alveolar bone crest (ABC) distance in healthy 6- to 9-year-old Jordanian children and determine the effect of pathological changes, physiological changes, gender, and age on the CEJ–ABC distance. Design. Bitewing radiographs were made for 539 6- to 9-year-old children. Plaque index (PI), gingi- val index (GI), calculus index (CI), DMFS score, and pocket depth were all assessed through clini- cal examination. CEJ–ABC distance was measured from radiographs at the mesial surface of perma- nent first molars (PFM), and the mesial and distal surfaces of primary molars. Results. The CEJ–ABC distance ranged from 0.00 to 4.49 mm, the mean for all surfaces was 0.84 ± 0.44 mm, no gender or age group differ- ences were found. The mesial surface of the PFMs had the smallest mean CEJ–ABC distance. The CEJ–ABC distances were greater in the maxilla than in the mandible. No significant effect of PI, GI or CI on CEJ–ABC distance was found. Caries, faulty restorations, exfoliation, and partial eruption adjacent to measured sur- faces had significant effect on the CEJ–ABC distance. Conclusion. The mean CEJ–ABC distance was <1 mm. Threshold CEJ–ABC distances of 1.0 and 1.5 mm for PFMs and primary molars, respec- tively, are suggested to be used in 6- to 9-year-old children. Introduction Periodontal disease in the primary dentition is generally limited to the gingival tissues result- ing in gingivitis; however, deeper involve- ment of the periodontium is occasionally seen 1 . One method for identification of indi- viduals susceptible to periodontal breakdown is the early detection of bone loss in the pri- mary dentition. For instance, it had been found that patients with localized juvenile (aggressive) periodontitis exhibited bone loss in the primary dentition in early childhood 2 . The correct diagnosis of periodontitis requires the concurrence of bleeding on prob- ing and loss of periodontal support, however, assessments in large epidemiological surveys have focused only upon the accumulated destructive effect of the disease revealed by clinical measurements of loss of attachment or radiographic measurements of loss of mar- ginal bone 3 . The diagnosis of marginal bone loss in the primary dentition includes the measurement of the distance between the cementoenamel junc- tion (CEJ) and the alveolar bone crest (ABC) and therefore, baseline information on the nor- mal range of CEJ–ABC distances is necessary for the diagnosis of abnormal bone levels 4 . Most studies of normal alveolar bone height are on the permanent dentition, and the radiographic interproximal CEJ–ABC distance in health has been reported to range between 1 and 3 mm 5,6 . Benn, however, found that the normal distance for adults ranged from 0.1 to 1.9 mm 7 . Very few studies on normal bone height in the primary dentition exist, these studies reported a normal CEJ–ABC distance of 1 ± 0.5 mm in the primary denti- tion 1,8,9 , and a distance of more than 2 mm is usually considered to represent bone loss 1 . In general, the normal CEJ–ABC distance reported in the literature ranged between Correspondence to: G. Al Jamal, Department of Preventive Dentistry, Jordan University of Science and Technology, P.O. Box 4614, Irbid 21110, Jordan. E-mail: ghaidaa@just.edu.jo; olabt@hotmail.com Ó 2010 The Authors International Journal of Paediatric Dentistry Ó 2010 BSPD, IAPD and Blackwell Publishing Ltd 151 DOI: 10.1111/j.1365-263X.2010.01073.x