Methods: The study was of a randomised, double-blind, split-mouth design. The test toothpaste contained proven anti-plaque/anti-gingivitis agents, namely stannous and zinc ions (1% stannous pyrophosphate, 0.5% zinc-citrate trihydrate), and fluoride; the control was a standard fluoride toothpaste. 36 subjects (19 females, 17 males) completed the study.
From a baseline of gingival health, achieved by 2 weeks of meticulous oral hygiene, adult volunteers entered the 18 days experimental phase. During this, subjects applied twice daily the test toothpaste to one quadrant of the mandible and the control toothpaste to the other (1 min each), using two separate, custom-made tooth-shields; carry-over of paste between quadrants was minimised. Test/control quadrants were assigned at random within subjects. Also, subjects brushed their maxillary teeth with the control toothpaste while the tooth-shields covered the mandibular teeth.
The gingival condition (teeth 3-7) was assessed at baseline, and day 5, 12, 18 using the Bleeding Index (Saxton and van der Ouderaa), the Modified Gingival Index (MGI) and the Lobene Plaque Index. Plaque zinc concentrations in test and control quadrants were determined at the start and end of the study. The data were analysed by ANOVA.
Results: The quadrants exposed to the test toothpaste had reduced mean MGI values compared to the control paste (17% males, 18% females); also, the mean bleeding index was reduced by 32% (males) and 25% (females), and the plaque index by 9% (males) and 12% (females). These differences between test and control quadrants were statistically significant (p<0.05). At day 18, the mean zinc concentration in test quadrant plaque was 110ppm higher than at baseline (p<0.001) but remained unchanged in control quadrant plaque.
Conclusion: The study confirmed that a split mouth experimental gingivitis model can be used to evaluate gingival benefits of toothpaste.