Analysis of Plaque Accumulation

Objectives: Löe and colleagues described the development of dental plaque in one day increments for 10 days in 1972 using fluorescein disclosing and high speed film photography with shadowgraphic enhancement for image analysis. This current study will focus on the first two days of plaque accumulation that have been used more recently to assess oral hygiene plaque control.

Methods: Dental plaque was disclosed with sodium fluorescein, USP, prepared in mildly alkaline phosphate buffer with the same buffer used to rinse before and after disclosing. Replicate digital photographs were taken with 365nm flash units at 12 hour intervals to 48 hours with no oral hygiene, but without dietary or personal restrictions. Plaque accumulation was characterized with commercial software.

Results: Plaque accumulation in the first 12 hours after brushing with cleansing control dentifrice was different than the second 12 hours. The plaque accumulation in the first 24 hours after brushing seemed to be the more consistent period of accumulation. Plaque accumulation in the first 48 hours was not linear with time. Greater plaque accumulation seemed to occur more frequently in the first 12 and 24 hours.

Conclusions: In addition to the usual study inclusion criteria, subject selection should be based primarily upon plaque accumulation after brushing with cleansing dentifrice for the same duration as is planned for the clinical study.  Subject selection of study subjects based on 12 hour plaque accumulation may result in a substantial over-estimated of plaque accumulation at 24 and 48 hours. Although 48 hour plaque accumulation may be somewhat greater than 24 hour plaque, the accumulated 24 hour plaque is more study friendly and represents the mean of life’s kinetic intervals of day (physical activity plus eating and oral activity) and night (quiescence).

This study was supported in part by the Colgate Palmolive Company and Odontex, Inc