Synthesis and Evaluation of Antimicrobial, Anti-inflammatory, and Antioxidant Activities of a 4-Hydroxycinnamic Acid Dentifrice for Orthodontic Subjects: An In Vitro Study.

Abstract

Aim: To prepare and test the antimicrobial (AM), anti-inflammatory, and antioxidant activities of a novel dentifrice containing 4-hydroxycinnamic acid (4-HCA).

Materials and methods: A novel base dentifrice was formulated with 0.2% 4-HCA (group II) and 0.4% 4-HCA (group III), and compared against a standard commercial dentifrice: Colgate Strong Teeth toothpaste (group I). Antimicrobial activity against Streptococcus mutans (SM), Lactobacillus acidophilus (LA), Candida albicans (CA), and Enterococcus faecalis (EF) was assessed by agar well diffusion zone of inhibition (ZOI), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Anti-inflammatory effects were evaluated using bovine serum albumin (BSA) denaturation and red blood cell (RBC) membrane stabilization assays. Antioxidant potential was measured by hydroxyl radical scavenging and ferric reducing antioxidant power (FRAP) assays. Statistical analysis utilized one-way analysis of variance (ANOVA) with appropriate post-hoc tests for ZOI and (p < 0.05).

Results: Group III exhibited significantly larger ZOIs against SM (39 ± 5.477 mm) as compared to group I (18.6 ± 2.4) (p = 0.05). The MIC for SM and LA was 0.5 mg/mL for all groups. Minimum bactericidal concentration was 0.5 mg/mL for LA and for SM in group III, whereas it was 5 mg/mL for all other groups. Minimum bactericidal concentration was 5 mg/mL for groups II and III. For anti-inflammatory activity, group III showed 43% inhibition in BSA denaturation at a concentration of 10 μg/mL, while group I showed 41% inhibition (p = 0.3). Similarly, groups II and III demonstrated antioxidant effects in the FRAP assay (66.28 and 66.49%, respectively) vs group I (64.89%) at 10 μg/mL (p = 0.5).

Conclusion: The novel dentifrice containing 0.4% 4-HCA demonstrated significant in vitro AM activity, particularly against SM, and exhibited promising anti-inflammatory and antioxidant properties compared to Colgate dentifrice. These findings highlight the potential of 4-HCA dentifrice as an adjunctive oral hygiene aid to reduce the risk of white spot lesions (WSLs) in orthodontic patients, underscoring the need for future clinical trials to establish its efficacy and safety.

Clinical significance: A dentifrice containing 4-HCA may serve as a promising adjunct in orthodontic patients for controlling microbial load and reducing the risk of WSLs. Beyond its in vitro efficacy, these findings indicate potential clinical translation as a preventive oral hygiene measure that could be incorporated into routine orthodontic care to improve enamel protection and treatment outcomes, provided future in vivo studies confirm its safety and effectiveness.