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NCT Number: NCT07091890

Effects of Topical Fluoride in Orthodontic Patients

This study was born from the need to improve caries prevention in orthodontic patients, a group particularly at risk. Fixed orthodontic appliances make daily oral hygiene more difficult, leading to increased plaque accumulation and the proliferation of cariogenic bacteria such as Streptococcus mutans and, more recently, Selenomonas sputigena. Although the latter does not cause cavities on its own, it enhances the action of Streptococcus mutans, making the caries process more aggressive.

The aim of the research was to evaluate the effectiveness of two different types of professional topical fluoride-gel and varnish-in reducing the presence of these bacteria and improving certain clinical parameters, such as salivary pH, the DMFT index (which measures decayed, missing, and filled teeth), and the Plaque Control Record (PCR%).

The study involved 45 patients, all between 8 and 17 years old and wearing fixed orthodontic appliances. They were divided into three groups: one received fluoride gel, another received fluoride varnish, and the third group underwent only a professional oral hygiene session, without any fluoride application. All patients were evaluated at the beginning of the study (T0) and again after four months (T1), both clinically and microbiologically, through saliva and plaque analysis.

The results showed that in the fluoride-treated groups-especially the varnish group-there was a significant reduction in plaque, an improvement in salivary pH (mainly in the gel group), and a decrease in the presence of S. mutans and S. sputigena. Furthermore, there was a reduction in oral Streptococci and Lactobacilli levels in the treated groups, whereas these levels increased in the control group. Interestingly, although not all differences were statistically significant, the improvements observed in the treatment groups suggest a clinically relevant benefit of topical fluoride, especially in varnish form.

In conclusion, professional application of fluoride-whether in gel or varnish form-proved effective in counteracting key bacteria responsible for dental caries in orthodontic patients and in improving several relevant clinical parameters. This confirms the importance of combining professional oral hygiene with specific fluoride treatments in patients wearing orthodontic appliances.

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Key information

Age range

6 year–20 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Integrated University Hospital Company Verona

Verona, 37134, Italy

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 1 < DMFT < n-1 (n= number of teeth present in the oral cavity)
  • age between 8 and 17 years
  • patient wearing fixed orthodontic appliances

Exclusion criteria

  • DMFT = 0 *; professional topical fluoride prophylaxis session carried out in the last 3 months
  • patient not wearing fixed orthodontic appliances
  • orthodontic treatment already completed or not started * DMFT refers to a caries prevalence index related to the presence of Decayed, Missing, Filled Teeth due to caries (Decayed, Missing, Filled Teeth).

Treatment and study plan

Fluoride gel

Device

After non-surgical therapy, 6-8 g of a gel containing 12,500 ppm of fluoride was applied for 4 min using a disposable tray appropriately sized for the patient's mouth. As per the guidelines, the patient was asked to briefly rinse their mouth with water. The aim was to remineralize the dental enamel to make it less susceptible to acid attacks caused by low salivary pH and the byproducts of bacterial metabolism

Fluoride varnish

Device

After non-surgical therapy, a fluoride varnish containing 7,700 ppm of fluoride in a homogeneous solution was evenly distributed over the dental surfaces using a micro-brush. Patients were instructed to spit out excess saliva but not to rinse their mouth with water, and to refrain from eating or drinking for at least 60 min afterward. After drying, the varnish formed a fluoride-rich layer on the enamel, increasing the concentration by up to four times. Despite the high concentration of fluoride, the resin component of the varnish allowed for a slow, controlled release of fluoride over time, thus preventing its immediate loss and minimizing the amount ingested by the patient. The purpose was to prevent mineral loss from the enamel and promote its restoration, making the dental tissue more resistant to the acidic pH of saliva caused by the production of organic acids through bacterial metabolism.

Primary outcomes

  1. Quantitative evaluation of Streptococcus mutans

    Time frame: T0 baseline, T1 4 months

    Molecular methods Polymerase Chain Reaction - Quantitative Polymerase Chain Reaction (PCR-qPCR)

  2. Quantitative evaluation of Selemonas sputigena

    Time frame: T0 baseline, T1 4 months

    Molecular methods Polymerase Chain Reaction - Quantitative Polymerase Chain Reaction (PCR-qPCR)

Secondary outcomes

  1. Plaque Control Record

    Time frame: T0 baseline, T1 4 months

    The Plaque Control Record (%) indicates the percentage of the tooth surface covered by bacterial plaque. The percentage was calculated by dividing the number of tooth surfaces with plaque by the number of areas examined and then multiplying the result by 100. Four surfaces were examined for each tooth: buccal, lingual/palatal, mesial, and distal surfaces. The highest value is 100% and it means that plaque is present on all the surfaces.

  2. DMFT

    Time frame: T0 baseline, T1 4 months

    The DMFT is a caries prevalence index that refers to the presence of Decayed, Missing, Filled Teeth due to caries (Decayed, Missing, Filled Teeth). The individual value for the patient is the sum of D+M+F. The highest score is 32 and it shows the greatest value for this index.

  3. Salivary ph

    Time frame: T0 baseline, T1 4 months

    To assess salivary pH, a specific pH reagent strip was moistened with the patient's saliva. After an appropriate waiting period, as indicated by the manufacturer of the saliva test, the color displayed by the strip was compared to that on the reference scale to read the result. The scale of pH is: <6,5 acid; 6,5-7,5 neutral; >7,5 alkaline.

Sponsors and collaborators

Lead sponsor

Universita di Verona

Other

Registry information

Official study title

Microbiology and Clinical Efficacy of Professional Topical Fluoride on Streptococcus Mutans and Selemonas Sputigena in Orthodontic Patients: a Randomized Clinical Trial

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Jul 29, 2025
Registry last updated
Jul 29, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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