Marginal bone loss in the primary dentition of patients with juvenile periodontitis

118 patients with juvenile periodontitis (JP), diagnosed when the patients were 13-19 years old, were studied retrospectively with respect to radiographic marginal bone loss in the primary dentition, experienced when the patients were 5-12 years old. 168 other 13-19 year old patients without any signs of bone loss in the permanent teeth were used as a reference group. The JP patients were classified into 2 groups according to the number of sites with bone loss in the permanent dentition: JP group I having 1 site with bone loss (n = 45) and JP group II having > or = 2 sites with bone loss (n = 73). It was found that 35 patients (52%) of JP group II displayed 1 or more sites with bone loss in the primary dentition during the age of 5-12 years. The corresponding numbers for JP group I and the reference group were 9 (20%) and 8 (5%) respectively. These findings indicate that juvenile periodontitis, at least in some individuals, may have its onset already in the primary dentition.