Two different Fluoride varnish systems(Fluoride varnish containing Chlorhexidine and Cetylpyridinium Chloride (CPC) and conventional fluoride) will be applied to high caries risk patients to assess their clinical effects on plaque accumulation and plaque bacterial count .

Preoperative steps:

• The diagnostic chart will be filled including all data about the patient's medical history, dental history, plaque assessment and plaque bacterial count.
• Scaling and polishing will be carried out for subjects.

clinical steps:

• Control Group: Conventional Fluoride varnish (Fluor Protector, Ivoclar Vivadent - Schaan Liechtenstein) will be applied on dry teeth in a thin layer, allowed to dry for 1 minute, and participants will be instructed to avoid rinsing after application, only spitting. Eating, drinking and brushing should be avoided for 1 hour after varnish application.
• Intervention Group: Varnish containing Fluoride, Chlorhexidine and Cetylpyridinium Chloride (Cervitec F, Ivoclar Vivadent - Schaan Liechtenstein) will be applied on dry teeth in a thin layer, allowed to dry for 1 minute, and participants will be instructed to avoid rinsing after application, only spitting. Eating, drinking and brushing should be avoided for 1 hour after varnish application.

Each participant will be assessed for plaque retention using plaque index and Standardized photography and image analysis to disclosed dental plaque, and plaque bacterial count using culture media sensitive for mutans streptococci (MS) in the following intervals:

• Enrolment Baseline assessment
• First visit (2nd week)
• Second visit (4th week)
• Third visit (12th week)
• Fourth visit (24th week)

Inclusion Criteria:

Patients with good general state of health.

• No signs of periodontitis.
• Patients had a recorded high bacterial count after caries risk assessment.
• No antibiotic treatment within 1 month prior to the start of the trial.
• No current medication with anti-inflammatory drugs.
• No use of antiseptic mouth rinses.
• Non-smokers.

Exclusion Criteria:

• Patients with disabilities, systemic disease or severe medical conditions.

  • Patients with severe or active periodontal disease.
  • Antibiotic treatment within 1 month prior to the start of the trial.
  • Current medication with anti-inflammatory drugs.