SYNTHESIS AND IN VITRO CHARACTERIZATION OF A PROBIOTIC-ENRICHED PROPHYLACTIC POLISHING PASTE

Background: Scaling roughens the tooth surface, increasing susceptibility to bacteria, and making polishing paste essential post-procedure. A paste with probiotic effects and nanoparticles efficiently smooths enamel and repairs microdamage. Lactobacillus helps prevent harmful bacteria, supporting oral health. Nano-silica enhances polishing, while nanohydroxyapatite remineralizes enamel.
Aim: Our study aimed to develop a prophylactic polishing paste incorporating Lactobacillus plantarum MTCC 5690, nano-silica, and nano-hydroxyapatite particles and to evaluate its in vitro properties, such as cytotoxicity activity, antimicrobial activity, and surface roughness.
Materials and Methods:This is an in vitro study conducted in Green Lab, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, Tamil Nadu, India between August 2024 and September 2024. A novel prophylactic polishing paste was formulated with bioactive and probiotic components. The base comprised glycerin (25%) and sorbitol (25%) in a 1:1 ratio, with deionized water and Carbopol (1–2%) for viscosity. SiO₂ and hydroxyapatite nanoparticles were added for abrasive and remineralizing effects.
Peppermint oil (0.2%), sodium fluoride (0.32%), and sodium benzoate (0.15%) were included for flavor, anti-caries action, and preservation, respectively. The pH was adjusted to ~7.0. After cooling below 40 °C, Lactobacillus plantarum MTCC 5690 (10⁸–10⁹ CFU/mL) and xylitol (2–5%) were added, followed by pH adjustment (5.5–7.0) to maintain probiotic viability. The final paste was homogenized and filtered for oral application and evaluated for its in vitro properties.
Results: The SEM image at 23,000× magnification revealed densely packed, heterogeneous angular structures with individual nanoparticles distinguishable at the 0.5 μm scale. In contrast, at 19,000× magnification, the particles appeared more compactly merged, suggesting the incorporation of L. plantarum, while irregular clusters and plate-like formations were identified as hydroxyapatite aggregates. The cytotoxicity analysis showed increased cell viability with higher concentrations of the prophylactic paste, peaking at 75 µL/mL. Fluorescence microscopy of MG-63 cells treated with prophylactic polishing paste showed dose-dependent viability. The control had sparse cells with low fluorescence, while 50 µL/mL treatment yielded the highest cell density and healthy morphology. Lower doses and control showed smaller, less spread cells, indicating mild cytotoxicity; higher doses promoted cell growth. The antimicrobial activity at low concentrations with inhibition zones slightly smaller than antibiotics. At high concentrations, the paste produced thelargest inhibition zones, exceeding those of antibiotics, demonstrating strong antimicrobial efficacy. Surface
roughness analysis revealed a significant reduction in roughness post-polishing, with area roughness (Sa) decreasing from 51.559 nm to 37.532 nm, highlighting the paste's ability to smooth the tooth surface and reduce plaque accumulation.
Conclusion:The formulated prophylactic polishing paste demonstrated strong antimicrobial activity and biocompatibility and enhanced cell viability in a dose-dependent manner and significantly reduced surface roughness post-polishing, and is beneficial for patients with gingivitis and periodontitis.