This trial is to test the caries prevention effect of Arabic gum and Licorice root extracts compared to Chlorhexidine in high caries risk patients. The antimicrobial efficacy and oral side effects from using these mouthwashes will also be tested.

To evaluate the effect of Arabic gum (Acacia gum) and Licorice (Glycyrrhiza Glabra) mouthwashes in comparison to Chlorhexidine mouthwash on reducing caries incidence (development of new caries lesions), antimicrobial efficacy and the prevalence of oral side effects (adverse events) in high caries risk patients.

P: Population with high caries risk patients I1: Arabic Gum mouthwash I2: Licorice mouthwash C: Chlorhexidine mouthwash O1: (Primary outcome) incidence of new caries lesions O2: (secondary outcome) antimicrobial efficacy O3: oral side effects (adverse events) from mouthwash use

Inclusion Criteria:

• High caries risk patients according to CAMBRA caries risk assessment tool
• Baseline of at least 2-3 active non-cavitated or cavitated carious lesionssz
• Baseline salivary Mutans streptococci count ≥ 106 CFU/ml
• Baseline salivary Lactobacilli count ≥ 104 CFU/ml
• Baseline DMF index of at least 3-5
• Cooperative patients approving to participate in the study

Exclusion Criteria:

• Any systemic conditions, severe medical complications
• Significant past or current medical condition that may affect oral health or oral flora
• Current medications (may affect the oral flora or salivary flow)
• Allergy to any of the ingredients of the study products
• Use of any antibiotics within the past 3 months
• Use of any mouth rinses within the past 3 months
• Current periodontitis (sites of probing pocket depth ≥ 5 mm)
• Evidence of parafunctional habits
• Dysfunction of temporomandibular joint
• Presence of developmental dental anomalies
• Presence of orthodontic appliance or removable prosthesis
• Pregnancy
• Xerostomia
• Heavy smoking
• Drug or alcohol addiction, or conditions that may decrease adhering to study protocol
• Lack of compliance