The Role of Fluoride Varnish Application in Preventing White Spot Lesions During Clear Aligner Treatment: A Controlled Split-Mouth Study

aim of study: is to compare the effect of the fluoride varnish application on the prevention of white spot lesions (WSLs) during clear aligner therapy in comparison to a split mouth-controlled group

Sample size calculation:

The sample size was calculated using G* power software (version3.1.9.7) and was designed to have a power of 85% assuming a type I statistical error of 5% and a one tailed statistical test with an effect size f= 0.7730012 based on the study of Najafi et al. The means and standard deviation of the DIAGNOdent score of the varnish and control groups after six months were 1.23 ±0.45 and 1.78±0.90. The calculated sample size will be 25 patients. The sample size will be increased to include 30 patients to avoid any drop out.

Material and methods:

1. Initial Oral Scan:

• A 3D oral scan of the arch to be treated will be performed using a digital intraoral scanner

1. Aligner Fabrication:

• aligners will be fabricated using thermoforming techniques.
• A clear aligner sheet (e.g.Duran) is heated and vacuum or pressure-formed over the 3D-printed model, then trimming followed by finishing and polishing

1. Interventions

Intervention Group (Test Side):

• Application of a preventive fluoride varnish (Charm varnish) on the indicated side of the mouth before clear aligner fitting.

Control Group (Control Side):

• Without application of fluoride varnish 4. Aligner Placement:
• The aligners will be fitted, and patients will wear them continuously, except during eating and brushing.

Outcome Measures:

Primary Outcome:

• Incidence and Severity of White Spot Lesions Measured before and after six months using Laser fluorescence (DIAGNOdent)

Secondary Outcome:

1. Periodontal Ligament (PDL) Health using:

• Pocket Depth Index (PDI)

1. Gingival Bleeding and Inflammation using:

• Bleeding on Probing Index (BOP)

Randomization and Application Site

To minimize bias, the side of the maxillary arch (right or left upper side) for fluoride varnish application was randomly assigned for each of the patients using a computer-generated randomization sequence

Inclusion and Exclusion Criteria Eligible participants were patients aged 16-24 years, representing the typical demographic for clear aligner therapy and ensuring biological consistency in terms of tooth development and orthodontic response. All participants were required to be in good general and oral health to minimize confounding factors related to systemic or oral disease, to present with mild dental crowding in each arch to standardize treatment complexity, and to have full eruption of all permanent teeth excluding third molars to allow consistent varnish application and assessment. Patients were excluded if they had a known allergy or hypersensitivity to fluoride-containing materials, systemic conditions that could affect tooth movement (such as diabetes or bone metabolism disorders), cleft lip and/or palate or other craniofacial anomalies, a history of previous orthodontic treatment, or clinical evidence of dental fluorosis, as these factors could alter enamel characteristics, orthodontic response, or lesion assessment and thereby introduce bias into the study outcomes.

Duration of the study:

• This study is suggested to be finished in 18 months