Fluoride Varnish Application - A guide for nurses

FLUORIDE-VARNISH-APPAccording to the General Dental Council (GDC), dental nurses are able to carry out fluoride varnish application on prescription from a dentist or via a dental health programme. This extended duty falls under ‘additional skills’ – dental nurses must be suitably trained in order to carry out such duties. 

What is fluoride? 

Fluoride is a naturally occurring mineral belonging to the halogen family. It is the thirteenth most common element and is found naturally in fish and tea. Some areas of the UK – supplying some 330,000 people – have naturally occurring fluoride in their water. The mineral is also a constituent of the human body. 

Products containing fluoride include toothpastes, mouthwashes, gels, varnishes and supplements. and fluoridated (this can occur naturally, as noted above, or it can be artificially 'topped up'). The fluoride content of a product is commonly referred to as parts per million (PPM) or as a percentage. 

Methods of delivery 

Delivery of fluoride includes ‘individual’ and ‘population’ methods. Individual methods include fluoridated toothpastes, mouthwashes, gels, varnishes and supplements. Population methods include fluoridated water, milk and salt (in some countries).

How fluoride affects the tooth surface

The modes of action of fluoride can occur at two stages: pre-eruptive and post-eruptive. 

At the pre-eruptive stage, the enamel becomes more resilient to acid effects/demineralisation. At the post-eruptive stage, fluoride has a detrimental effect on formation of bacterial plaque and will also aid remineralisation.

Availability as a varnish

Perhaps the most common type of fluoride varnish (and the only one carrying a licence to prevent caries) is Colgate's Duraphat. Duraphat is a prescription-only medication (POM) and is available in a 10ml tube containing 50mg sodium fluoride (NaF) per 1mg. 

The practice of applying fluoride varnish spans some three decades, and its effectiveness has been well-documented. It continues to show success in caries prevention.  

When to use

Caries prevention – most commonly used in the post-eruptive stage before calcification has completed. It is particularly common for fluoride varnish to be applied to the first permanent molars. However, individual assessments and appropriate applications should take place.

Hypersensitivity – this may be due to sensitivity after professional cleaning, enamel injury or exposed dentine.

Application process 

Prior to application:

  • Informed consent must always be given by the patient or parent/guardian.
  • An appropriate medical history should be taken. An episode or episodes of hospitalisation with allergies such as asthma contra-indicate the use of fluoride varnish.
  • It should be ensured that the varnish is in date.
  • Sterilised equipment and appropriate disposables must be available.
  • The clinical setting must be clean and personal protective equipment must be  supplied to the patient and clinician.
  • The correct amount of varnish must been dispensed. In the case of application to first permanent molars on a six-year-old, 0.4ml is suitable.
  • Intra-oral assessment must be carried out and it should be confirmed that no abnormalities are present. Assessment should include the tongue, cheeks, gingivae and teeth. If any abnormalities/dental disease are present, application should be delayed and the attention of the GDP sought.

For application to lower left first permanent molar:

  1. Lower left cheek retracted.
  2. LL6 dried with cotton wool roll/pledget.
  3. Fresh cotton wool roll placed in left buccal sulcus.
  4. Suitable amount of fluoride varnish applied using a brush/pledget – priority should be given to more susceptible surfaces such as occlusal/interproximal.
  5. After-care advice given.
  6. Full and contemporaneous notes recorded.

After-care advice given

Following the application of fluoride varnish, the patient should avoid rinsing/drinking for approximately thirty minutes. Brushing teeth/eating should be avoided for the following four hours. This information should be communicated to the parent/guardian present; if necessary, it should also be provided in writing. It is important to reassure the patient that the varnish will be removed with brushing (some can be concerned about the colour). It may be also be a good idea to encourage eating/drinking prior to the varnish application.

Frequency of application

According to the Department of Health's guidelines: 

  • All children aged 3–6: twice each year.
  • Children aged 0–6 causing concern*: twice or more each year.
  • 7 years–young adults: twice each year.
  • 7 years–young adults causing concern*: twice or more each year.
  • Adult patients causing concern*: twice each year. 

*Patients causing concern also require other professional intervention, such as dietary investigation, sugar-free medications where possible, reduction of recall interval, fissure sealants, daily fluoride rinses, or prescription of high-fluoride toothpaste (age-appropriate). 

When NOT to apply fluoride varnish

 Medical/dental reasons to avoid fluoride varnish application: 

  • History of allergic episodes requiring hospitalisation, such as asthma.
  • Soft tissues pathology; ulcerative gingivitis or stomatitis. 

Other reasons: 

  • No prescription (if carrying out in situation other than structured oral health 
  • programme).
  • Issue with materials, i.e. they are out of date.
  • Consent denied.
  • Not indemnified. 
  • Insufficient instruments/disposables/PPE.

Caries prevention rate

Systematic reviews have shown caries reduction rates of up to 37% in the primary dentition and 43% in the secondary dentition. 

Side effects/risks: 

Side effect: Dental fluorosis. 

Since the 1930s, the relationship between fluoride and dental fluorosis has been recognised as a well-known potential side effect. Dental fluorosis is characterised by a white speckling on the enamel surface. In the UK, dental fluorosis tends to be mild, with 1-4% of the population presenting with cosmetically significant lesions. Dental fluorosis is caused by immoderate ingestion of fluoride through methods such as toothpaste, mouthwashes, fluoridated water (natural or artificial), supplements and varnishes. After approximately the age of seven, there is no apparent risk of fluorosis as formation of the secondary dentition has taken place.

Risk: Toxicity. 

As with any drug of high concentration, there is a risk of toxicity. It is estimated that the toxic dose is 5 milligrams (mg) per 1 kilogram (kg) (5mg/kg) of body weight. 

Therefore, for an average six-year-old weighing approximately 22kg, the toxic level is 110mg. For an average-sized adult weighing approximately 75kg, the toxic level is 375mg. 

The amount of sodium fluoride available in one 10ml tube of Duraphat is 500mg, as 1ml of Duraphat contains 50mg of sodium fluoride. These figures demonstrate why appropriate distribution amounts are necessary and why careful storage of Duraphat is so important.

Signs of toxicity: 

Stomach pains, vomiting, nausea and headaches.

Treatment of toxicity

Summon emergency services/other members of the dental team.


Fluoride varnish should be kept in a cool, dry place and disposed of if not used within three months. The area of storage should be inaccessible to patients, as some fluoride varnishes are prescription drugs. 

How will fluoride varnish application improve my work?

Adding another activity to your skill set improves what you have to offer – not only to your patients but to your existing/future employers. Some areas of the UK run structured oral health programmes such as Child Smile in Scotland or Designed to Smile in Wales. These programmes involve Extended Duties Dental Nurses (EDDNs) applying fluoride varnish to children’s teeth outside of a practice setting. Fluoride varnish application works particularly well in conjunction with the Oral Health Education certificate and running your own OHE/fluoride clinic.

Where can I study the course?

The course may be available through your local deanery. Social media is another good way of sourcing course information. Dental Nurse Network are planning to deliver a classroom-based and online course in fluoride varnish application this year.

Author: K. Amber RDH 

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