# The Effect of Different White Spot Lesion Treatments on the Enamel Microhardness—An In Vitro Pilot Study

## TL;DR

This study compared how different treatments for white spot lesions affect the hardness of tooth enamel in a lab setting.

## Contribution

The study introduces a direct comparison of resin infiltration, fluoride varnish, and CPP-ACP on enamel microhardness in an in vitro model.

## Key findings

- Resin infiltration restored enamel microhardness to levels similar to healthy enamel.
- Fluoride varnish and CPP-ACP showed equivalent microhardness values, lower than the control.
- Resin infiltration significantly improved microhardness compared to untreated white spot lesions.

## Abstract

Background/Objectives: Dental caries, one of the most common oral diseases worldwide, represents a major public health concern. Contemporary dentistry has established several non-invasive approaches and resin infiltration, as a micro-invasive path, in the treatment of white spot lesions (WSLs). This study aimed to evaluate the effect of different WSL treatments on enamel surface microhardness. Materials and Methods: Seventy-five intact human premolars extracted upon orthodontic indication and the demineralizing solution composed of acetic acid, monopotassium phosphate and calcium chloride with pH = 4.4 and exposure time 96 h were used. The samples were randomly divided into five groups (n = 15): I—intact enamel (control group); II—artificial white spot lesion; III—artificial WSL treated with fluoride varnish; IV—artificial WSL treated with casein phosphopeptide—amorphous calcium phosphate (CPP-ACP) paste; V—resin-infiltrated artificial WSL. The surface microhardness was determined using the Oliver–Pharr method and a spherical indenter (Shimadzu Indenter, Kyoto, Japan). One-way analysis of variance (ANOVA) followed by a Post Hoc test (Bonferroni) was used with a level of significance set at p < 0.05. Results: Resin-infiltrated white spot lesions showed comparable microhardness mean value as the control group: 68.23 (±21.45) and 63.57 (±18.89), respectively (p > 0.05). Also, resin infiltration increased enamel microhardness compared to WSL values, with a statistically significant difference (p < 0.05). Fluoride varnish and CPP-ACP treatment resulted in equivalent values (50.84 ± 14.35 and 50.99 ± 15.31, respectively). Conclusions: Different WSL treatments (fluoride varnish, CPP-ACP and resin infiltration) produced comparable enamel microhardness values. Among the tested agents, resin infiltration resulted in higher microhardness values, while fluoride varnish and CPP-ACP demonstrated equivalent outcomes.