Silver Nanoparticle vs Chlorhexidine Mouthwashes for Reducing Streptococcus Mutans and Improving Salivary pH in Children

Dental caries remains the most prevalent chronic disease affecting children worldwide and continues to represent a major public health concern. The disease results from a complex interaction between dental biofilm, fermentable carbohydrates, susceptible tooth surfaces, and host factors. Among the microorganisms associated with caries development, Streptococcus mutans plays a central role because of its ability to adhere to tooth surfaces, synthesize extracellular polysaccharides, produce organic acids, and tolerate acidic environments. Consequently, reducing salivary and plaque levels of S. mutans is considered an important strategy for preventing and controlling dental caries in children at high caries risk.

Chlorhexidine gluconate is widely recognized as the reference antimicrobial mouthwash because of its broad-spectrum antibacterial activity and prolonged substantivity. Despite its effectiveness, routine use in pediatric patients may be limited by adverse effects, including tooth staining, taste alteration, oral mucosal irritation, and reduced patient acceptance during repeated use.

Silver nanoparticles (AgNPs) have attracted increasing interest as an alternative antimicrobial agent because of their broad-spectrum activity against oral microorganisms through multiple mechanisms, including disruption of bacterial cell membranes, interference with intracellular metabolic processes, and inhibition of biofilm formation. At appropriate concentrations, AgNP formulations have demonstrated favorable biocompatibility and may provide an alternative approach for reducing cariogenic bacteria while minimizing some of the undesirable effects associated with chlorhexidine.

This randomized, double-blind, parallel-group clinical trial is designed to evaluate the comparative effectiveness and safety of a silver nanoparticle mouthwash and a chlorhexidine mouthwash in children with high caries risk. The study will assess the antimicrobial effect of both interventions on salivary Streptococcus mutans while also evaluating changes in the oral environment and treatment tolerability. The findings are expected to provide evidence regarding whether silver nanoparticle mouthwash represents a suitable alternative to chlorhexidine for antimicrobial management in pediatric dentistry and to contribute to the development of safer and more acceptable preventive strategies for children at increased risk of dental caries.

Inclusion criteria

• Age 6-12 years with mixed dentition.
• American Society of Anesthesiologists (ASA) physical status I or II
• High caries risk, defined as DMFT/dmft score ≥ 3, Dentocult SM Strip mutans score ≥ 2, or salivary S. mutans ≥ 10⁵ CFU/mL at screening
• Presence of at least 20 natural teeth.
• No antibiotic therapy in the preceding 3 months.
• Parent/guardian willing to provide written informed consent.
• Child assent obtained using age-appropriate methods.

Exclusion criteria

• Systemic diseases affecting salivary flow (e.g., Sjögren's syndrome, uncontrolled diabetes, cystic fibrosis).
• Special healthcare needs or developmental disabilities affecting. compliance
• Active fixed or removable orthodontic appliances.
• History of allergy to silver compounds, chlorhexidine, or mint flavoring.
• Use of any antimicrobial mouthwash in the preceding 3 months.
• Active oral mucosal lesions or periodontal disease.
• Professional fluoride treatment within the past month.
• Participation in another clinical trial within the past 6 months.