Biological and measurement issues critical to design of gingivitis trials.

Chronic plaque-induced gingivitis is usually of little consequence, thus the concern about prevention and treatment must stem from the belief that preexisting gingivitis is necessary for periodontitis to develop. When clinical signs of gingivitis are present, an inflammatory infiltrate can be found upon histological evaluation. When clinical signs are absent, however, significant inflammation may still be present within the gingival tissues. Therefore, multiple clinical evaluations should be made, with special attention given to the visually inaccessible midinterdental area. The "gold standard" for evaluation of gingivitis is histological evaluation and other measurements should be evaluated against this standard. The significance of clinical severity measurements of gingivitis is not well-understood relative to onset of periodontitis; therefore, it is suggested that consideration be given to gingival evaluations based on the presence or absence of clinical signs of inflammation. Furthermore, equivalency and superiority of antigingivitis agents or devices should be predicated, at least in part, on their ability to prevent the onset of periodontitis.