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Evaluation of D&C Red No. 33 as an alternative to erythrosine for plaque disclosure: a randomized crossover trial
Sireerat Sooampon1, Yanin Bootyod2, Prakaydaw Panchanon2
1Department of Pharmacology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Background:
Plaque disclosing agents facilitate the visualization of dental biofilm and support effective oral hygiene instruction. Erythrosine remains the most commonly used agent; however, concerns regarding its safety and regulatory restrictions have prompted the search for alternative colorants. This study aimed to evaluate and compare the clinical performance and user acceptability of three plaque disclosing formulations: 3% erythrosine, 3% D&C Red No. 33, and a mixed formulation of 3% D&C Red No. 33 with green powder.
Methods:
A randomized cross-over clinical design was employed. Subjective outcomes were assessed using visual analogue scales (VAS) for plaque visibility, residual staining, brushing difficulty, and taste satisfaction. Objective plaque accumulation was measured with the Turesky modification of the Quigley-Hein Plaque Index (TQHPI) by a calibrated examiner before and after oral hygiene procedures.
Results:
Erythrosine produced the highest plaque visibility scores, significantly exceeding those of both alternative agents. However, all formulations showed comparable percentage reductions in plaque index following brushing and flossing. Residual staining was greatest with erythrosine, particularly on oral mucosa and lips, whereas D&C Red No. 33 produced the least. The mixed formulation yielded intermediate outcomes but demonstrated the lowest overall plaque visibility. Participants reported significantly greater difficulty in stain removal with erythrosine compared to D&C Red No. 33. Taste acceptability was highest for D&C Red No. 33, intermediate for the mixed formulation, and lowest for erythrosine.
Conclusions:
While erythrosine provides superior plaque visibility, its drawbacks in staining persistence, brushing difficulty, and taste limit acceptability. D&C Red No. 33 demonstrated a more favorable balance between effectiveness and user acceptance, supporting its potential as an alternative plaque disclosing agent.
Trial Registration:
The trial was registered at Thai Clinical Trials Registry (Trial registration number: TCTR20250313002) on 13 March 2025.
