Differential diagnosis of severe periodontal lesions.

In current clinical practice, a differential diagnosis of severe localized periodontal lesions is rarely made; such lesions are considered to be manifestations of periodontitis caused by specific microbes from the commensal oral flora. However, deep seated lesions of the periodontium which are in communication with the alveolar crest, are well documented periodontal consequences of pulpal pathoses and can mimic the signs and symptoms of 'periodontitis'. The very low incidence of tooth-threatening periodontal disease in ancient and modern man is revealed when differential diagnoses are used in the examination of alveolar defects in anthropological materials and when epidemiological studies use more appropriate indices. However, no periodontal index to date has incorporated a differential diagnosis between gingival and pulpal causes of alveolar bone loss. The gingival and periodontal signs of severe localized periodontal lesions are reviewed and the imprecise nature of current clinical diagnostic tests (radiography, 'pulp testing', darkfield microscopy, bleeding on probing, periodontal probing) is discussed. None of these tests is able to detect disease activity and cannot be used to predict future patterns of disease behaviour. However, the commonly held belief that the tests are accurate has resulted in most severe periodontal lesions being falsely labelled as periodontitis. Failure to carry out differential diagnosis of severe periodontal lesions has resulted in the instigation of periodontal therapy for many lesions of non-gingival origin. Whenever severe localized lesions of the periodontium are detected, the differential diagnosis between pulpal and periodontal origins should be made. The results of diagnostic tests in current use should be interpreted with extreme caution; clinicians are left to exercise their judgment based on consideration of all the available evidence.