In Vitro Evaluation of Enamel Carious Lesion Treatment with Curodont™ Repair Fluoride Plus

by Abigail | Sep 8, 2025

In Vitro Evaluation of Enamel Carious Lesion Treatment with Curodont^™ Repair Fluoride Plus

Authors: Matt Cowen, B.S., Margaret Gilmartin, B.S., John M. Powers, Ph.D.

Introduction:

This study evaluates the performance of Curodont^™ Repair Fluoride Plus (vVARDIS) in increasing the mineral density throughout the entire depth of an enamel carious lesion. Transverse microradiography (TMR) or MicroCT analysis of the lesions was conducted to compare the relative mineralization change from the initial to final state. Teeth were also sectioned and examined with high magnification scanning electron microscopy to examine the appearance of the hydroxyapatite 2 weeks post-treatment. An increase in mineralization of enamel can include different mechanisms including remineralization, the formation of new hydroxyapatite crystals and reformation of damaged hydroxyapatite crystals. The goal of this study was to determine if there is any difference in the location of the increase in mineral density, and visualize the appearance of hydroxyapatite.

The low-viscosity formulation penetrates the pseudo-intact enamel surface and disperses throughout the sub-surface lesion body. The proprietary formulation generates hydroxyapatite throughout the depth of the lesion, resulting in the restoration of the lost or damaged hydroxyapatite crystals, ultimately treating the early stage lesion and helping restore the natural tooth integrity.

Conclusions:

Curodont Repair Fluoride Plus was effective in restoring 14.3% of the mineral content through the entire lesion in only 2 weeks. There was no significant difference in where the increase in mineral density occurred from the surface to the deepest part of the lesion, showing effectiveness in restoring lost mineral content in subsurface lesions including hydroxyapatite generation.

Methods:

Sound human molars (n=3) were cleaned and sterilized in 0.1% Chloramine T solution and roots mounted in acrylic with crowns exposed for immersion in solution and scanning. Test areas were created on each tooth with an acid-resistant varnish protecting the underlying enamel outside of the test area.

Artificial superficial cavities were created via immersion in 40 mL of a demineralization solution (2.2 mM CaCl₂, 2.2 mM NaH2PO₄, 50 mM acetic acid; pH adjusted with 1 M KOH to 4.4) for 4 d at 37°C which created lesions with an average depth of 100 µm. An initial MicroCT scan with a Xradia Versa 520 X-Ray Microscope was made capturing the entire lesion. Lesions were then pretreated with 10 µL of 2% NaClO to remove the enamel pellicle, rinsed, and air-dried at room temperature followed by application of Curodont Repair Fluoride Plus per manufacturer instructions. Teeth were then immersed in remineralization buffer simulating saliva exposure, containing 2 mM Ca(NO₃)₂, 1.2 mM KHPO₄, and 60 mM Tris/HCl (pH adjusted to 7.4 with 1 M KOH) for 14 days while changing the solution every second day. A second scan was then made of the same areas with the same settings and orientation for the final condition.

***Fig 1.*** *Example of molar with area revealed for creating a lesion area.*

MicroCT Analysis:

Dragonfly 3D World software was used for MicroCT analysis. The before and after scans were aligned on top of one another and histograms were normalized with respect to one another. Intensity levels were calibrated to relative mineral density percentage of the sound enamel and underlying dentin. Lesions were segmented using a custom AI model and a mask of the lesion area extracted based on a 90% mineralization content of the initial condition and expanded to encompass the full lesion. Depth profiling of lesions with 5 depth profile measurements taken per lesion starting from the surface covering the entire lesion, and mineral density calculated every 2 microns based on intensity levels averaged over a 50-micron disc area. Mineral density was compared to initial and final states, and between product groups. Relative mineral density was quantified and compared by the intensity calibrated depth profile curves. Data was analyzed by ANOVA and Tukey multiple comparison test for pair-wise comparison at a p-value of 0.05.

*This is an exemplary depth profile up to 90% of the initial lesion. In all cases, there was significant increase in mineral density seen through the entire lesion.*

Results Summary:

This is the average mineral density from the initial to the final condition at 2 weeks, where 100% mineralization is sound enamel. The referenced distance is measured from the surface of the tooth. The average initial depth of lesions was 100 (27) µm for CRFP. There is no significant difference in mineral density based on the depth (ANOVA, Tukey, p>0.5). There were significant differences in mineral density from the initial state to after 2 weeks (p<0.001) with an average increase in mineral density of 14.3% after only 2 weeks in an artificial saliva solution. The increase in mineral density is likely due to multiple processes including formation of new hydroxyapatite crystals, reformation of existing damaged hydroxyapatite crystals and some superficial remineralization due to the artificial saliva solution. The SEM imaging of the untreated control group revealed large porosities, whereas treated teeth showed pore closure consistent with new hydroxyapatite crystal generation following Curodont Repair Fluoride Plus application.