RESUMEN
The end point methodology did not indicate a difference between the agents. The prophylaxis effect was only demonstrable through 8 weeks, although the analysis of variance indicated a prophylaxis effect on gingival index throughout the study. An agent effect was not demonstrable in the study. The "positive control," chlorhexidine, did not give the same results in this brushing study as in previous no-brushing studies reported by Loe and by our group. One might conclude that the effectiveness of brushing in reducing gingivitis is greater than the effect of chlorhexidine. Decreasing plaque and gingivitis scores are seen with increasing time, probably reflecting increased subject interest and involvement in the study. Mere involvement in the study apparently produced a beneficial effect on gingival health. This "placebo effect" also has been noted in an earlier study. A similar decrease in plaque scores in a placebo group attributable to a general improvement of oral hygiene was reported by Gjermo and Rolla. The subjects who began the study with no calculus (prophylaxis group) had consistently lower calculus scores than those not given a prophylaxis. This difference became less distinct at later exams, as the treated group developed calculus. The agents, although ineffective under the test regimen produced no adverse effects.