Comparative study of two evaluation methods on radiographic bone loss at the mandibular canines and incisors

The approximal bone loss of the mandibular canines and incisors was scored with two different units of measurement on 30 sets of standardized paralleling radiographs: 1) with absolute values ("true" millimeter) unrelated to casual variables and 2) with relative values (i.e. percentage of the root length). Absolute bone loss scores revealed that the space between the canines and the lateral incisors of the present material seemed to be more susceptible to bone loss than the spaces between the incisors, with a tendency towards the mesial bone loss of the canines being still greater than the distal bone loss of the laterals. There was a high degree of correspondence between absolute bone loss scores at different teeth and corresponding gingival pocket depths of a previous analysis by the present authors. Relative bone loss scores led to divergent and partly direct-opposite results compared with the absolute scores. The correspondence between percentage bone loss scores and gingival pocket depths at corresponding tooth surfaces was poor. When investigating the susceptibility of different teeth to periodontal breakdown it seems as if bone loss should be expressed in absolute values in the same way as are gingival pocket depths and loss of attachment. If a common standard is being used the results of different investigations may be compared. However, when studying the inception and advancement of the disease at the same tooth over a period of time, or when evaluating the remaining bone support the percentage bone loss method may be of clinical importance.