What portion of the trough area of the tray is filled during application of APF gel or foam?

 # What portion of the trough area of the tray is filled during application of APF gel or foam?

A. One third of the trough area of the tray

B. One half of the trough area of the tray

C. Three fourths of the trough area of the tray

D. Trough area of the tray is filled completely

The correct answer is A. One third of the trough area of the tray.

Clinical Rationale

When applying Acidulated Phosphate Fluoride (APF) gel or foam, the primary goal is to ensure the teeth are coated while minimizing the risk of the patient swallowing the excess material.

• Displacement: When the tray is inserted into the mouth, the patient's teeth will displace the gel or foam, pushing the level up to cover the cervical areas of the teeth.

• Safety: Filling the tray more than one-third full significantly increases the risk of the material overflowing. This can lead to:

  • Gagging: Due to excess material running down the throat.

  • Ingestion: Swallowing high concentrations of fluoride can cause nausea or gastric distress.

Application Guidelines

To ensure a safe and effective treatment:

• Quantity: Fill the tray only about 1/3 full (or approximately 2 ml to 2.5 ml of gel per tray).

• Foam: If using foam, be aware that it expands; however, the 1/3 guideline remains a standard conservative measure to prevent overflow.

• Suction: Always use a saliva ejector during the procedure to evacuate excess saliva and fluoride.

• Positioning: Keep the patient in an upright position with the head tilted slightly forward to prevent flow into the throat.