Methods: Dental plaque was disclosed with buffered mildly acidic and alkaline solutions of sodium fluorescein, USP, and photographed with a digital camera, computer and software system. Plaque with buffered fluorescein solutions was collected to determine the interactions between oral fluids, plaque and fluorescein using a Hitachi F7000 spectrofluorimeter to determine the frequency and intensity of the energizing illumination and the emitted fluorescence.
Results: Very high fluorescence was obtained with 490nM excitation. Excitation at 365nM was 1/10th this level with 265nM excitation producing an intermediate fluorescence. The disclosed plaque fluorescent area at alkaline pH was reduced ~40% with 285nM, but the disclosed plaque area with 365 and 490nM excitation was reduced 10%. At mild acidic pH, reduction in disclosed plaque area was 30% with 265nM, 20% with 365nM and 40% with 490nm excitation.
Conclusions: The fluorescence of disclosed plaque was quenched thus reducing both intensity and area with frequency of excitation, pH of the disclosing solution and characteristics of the pH buffering . Method specifics and interaction with oral fluids and products being assessed are fundamental to the definitive clinical study design.
Partial support for studies was provided by Colgate Palmolive Company and Odontex, Inc.
Keywords: Digital image analysis, Plaque, Teeth and Therapeutics