The Modified Gingival Margin Plaque Index - a Predictable Clinical Method

The Modified Gingival Margin Plaque Index (MGMPI), a published clinical method, measures plaque formation along the gingival margin over a 24 hour period. Previous publications indicated the MGMPI method to be as predictable as the long standing 4 day plaque re-growth model employing the Quigley Hein Plaque Index. In addition to providing the feasibility for fast proof concept information and subject friendly test duration, the method delivers a window of research opportunity to study plaque quality changes within 24hrs.

Objective: This analysis investigated whether the MGMPI method could consistently detect a significant difference between two control commercial products, specifically the ability of the method to predict anti-plaque efficacy of Colgate® Total® (CT), a well documented anti-plaque toothpaste containing a triclosan/copolymer/fluoride system vs. Colgate® Cavity Protection (CP), a regular fluoride toothpaste.

Method: The data from 28 MGMPI studies comparing CT to CP were analyzed, with sample size ranging from 9 subjects to 19 subjects. The difference between the baseline and the 24 hour final plaque score was calculated. A paired T-test determined if the delta scores for CT and CP demonstrated a significant difference as would be anticipated.

Result: Data analysis showed that CT had a lower mean delta score from baseline to final than CP. This difference was significant in 23 of the 28 studies representing a probability of success rate of 82 %. Subject numbers in the studies significantly impacted the output. The separation between CT and CP depends on the power of the study.

Conclusion: The MGMPI offers a convenient clinical method to measure anti-plaque efficacy of oral care products. With sufficient power in the study, it can predictably separate two standard controls CT vs. CP. This analysis further confirmed that MGMPI method is a valuable tool for clinical dental research and development of new oral therapeutics.