Suitability of gingival indices for use in therapeutic trials. Is bleeding a sine qua non?

A number of gingival indices have been described which include visual and invasive components, either separately or in combination. In selecting indices for use in gingivitis therapeutic trials, some investigators maintain that only invasive indices should be used, since indices that include a bleeding-on-provocation component are deemed to be the most objective. Other investigators, however, maintain that non-invasive indices are the more appropriate insofar as invasive procedures will not only disrupt the plaque at the gingival margin, but could also mildly traumatize the tissue and present an impediment to assessing examiner standardization and reproducibility. This paper discusses these aspects of gingivitis evaluation. The data indicate that all validated indices, whether invasive or non-invasive, have some degree of both objectivity and subjectivity. Therefore, the selection of an appropriate index will depend upon the ability of a given index to achieve the objectives of the clinical trial in which it is to be utilized.