Dental fluorosis can cause visible chalky-white spots on the front teeth. These white spot lesions may affect dental appearance even when the tooth surface is intact.

This randomized clinical trial compared two minimally invasive approaches for masking fluorotic white spot lesions on permanent anterior teeth. Eligible teeth were randomly assigned to receive either resin infiltration or enamel microabrasion followed by application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP).

The main outcomes were the color difference between the white spot lesion and the surrounding sound enamel and the proportion of the visible tooth surface occupied by the lesion. These outcomes were evaluated from standardized clinical photographs before treatment, after treatment, and during follow-up through 6 months.

This was a prospective, controlled, two-arm randomized clinical trial conducted at the Dental Clinic of the University of Medicine and Pharmacy Hospital, Hue University, Vietnam, between June 2023 and June 2025. Patients with fluorotic white spot lesions on permanent anterior teeth were enrolled. Eligible lesions were shallow, chalky-white enamel opacities confined to the outer enamel and clinically consistent with dental fluorosis.

Randomization was performed at the tooth level. A total of 60 eligible teeth were allocated in a 1:1 ratio to one of two treatment groups: resin infiltration or enamel microabrasion followed by CPP-ACP application. Allocation was concealed using sequentially numbered, opaque, sealed envelopes. All procedures were performed by one operator under standardized clinical conditions.

In the resin-infiltration group, the lesion surface was treated with 15% hydrochloric acid, rinsed and dried, followed by ethanol application. A low-viscosity resin infiltrant was then applied and light-cured according to the study protocol.

In the microabrasion plus CPP-ACP group, the labial enamel surface was treated with a hydrochloric-acid and silicon-carbide microabrasion material using repeated polishing cycles. CPP-ACP paste was then applied to the treated surface for 5 minutes.

Two co-primary outcomes were evaluated from standardized clinical photographs: the color difference between the lesion and adjacent sound enamel, expressed as ΔE in the CIELab* color space, and the lesion-area ratio, expressed as the percentage of the visible labial tooth surface occupied by the lesion. Images were obtained under reproducible lighting, magnification, camera-positioning, and patient-positioning conditions.

Color measurements were obtained from sampled points within the lesion and adjacent sound enamel. Lesion area and total labial-surface area were outlined and measured using image-analysis software. Outcome assessments were performed by an independent examiner who was blinded to treatment allocation using coded image files. Measurements were obtained before treatment and at prespecified post-treatment and follow-up assessments through 6 months.

Inclusion Criteria:

• Patients presenting with fluorotic white spot lesions on permanent anterior teeth.
• Shallow fluorotic white spot lesions confined to the outer enamel.
• Chalky-white lesions with a clear border from adjacent sound enamel.
• Lesions appearing bright on oblique visual inspection and mildly dim under diagnostic transillumination.
• Clinical diagnosis of dental fluorosis based on the characteristic bilateral, symmetrical, and diffuse distribution of enamel opacities.
• Willingness to participate in the study and comply with treatment and follow-up visits.

Exclusion Criteria:

• Deep subsurface enamel lesions.
• Lesions consistent with molar-incisor hypomineralization.
• Lesions with yellow or brown discoloration.
• Known allergy or hypersensitivity to ICON, Opalustre, Tooth Mousse, or their components.
• Inability to tolerate rubber-dam isolation.
• Poor oral hygiene.
• Inability or unwillingness to attend the scheduled follow-up assessments.