[Radiographic analysis of normal periodontal tissues].

The present study was designed to investigate the roentgenographic manifestations of clinically healthy periodontal tissues in two sample groups. One group consisted of dry skulls of 4 young subjects who had been reportedly healthy during lifetime. The other group included 31 healthy students aged 16-25 years. A set of 7 standardized bite-wing radiographs were taken in each mouth. 4x magnified photos were developed for measurement and assessment. The interproximal alveolar bone level (BC-CEJ distance) was determined by measuring the distance from the lowest point of alveolar bone crest to the imaginary line connecting the two CEJs of the adjacent teeth. Both the radiographic signs of lamina dura and of the PDL space were graded to compose Lamina Dura Index (LDI) and periodontal ligament space index (PDLI). It is found that the average distance of BC to CEJ in periodontally healthy subjects is from 0.62 to 1.67 mm. Radiographic signs such as disappearance of lamina dura on the alveolar bone crest, wedge-shaped widening of the periodontal ligament space at the bone crest are not uncommonly seen in clinically healthy periodontal sites. The frequency of these signs on teeth with normal periodontium and their distribution on tooth sites were also presented and discussed.