The Effects of Three Remineralizing Agents on the Microhardness and Chemical Composition of Demineralized Enamel

Published In: Materials
Publication Year: 2021

Study Design

This was an in vitro experimental study evaluating the effect of three different remineralizing agents on artificially demineralized human enamel using microhardness testing and SEM/EDS (scanning electron microscopy and energy-dispersive X-ray spectroscopy) analysis.

Funding Sources

The study was funded by the Croatian Science Foundation through the project titled:
“Research and Development of New Micro and Nanostructural Bioactive Materials in Dental Medicine”
Project No.: IP-2018-01-1719.

PICO Framework – What Was Studied and How?

Population:

Extracted healthy human third molars (N = 33) subjected to controlled demineralization.

Intervention:

Application of MI Varnish® (contains CPP-ACP and fluoride), 2x daily for 2 minutes over 14 days.

Comparison:

• 3M™ Clinpro™ White Varnish (fluoride only)

• Megasonex® toothpaste (nano-hydroxyapatite)

Outcomes:

• Enamel surface microhardness (measured via Vickers microhardness testing)

• Mineral composition (assessed via SEM/EDS)

In paragraph form:
This in vitro study assessed the remineralizing effects of three agents—fluoride, nano-hydroxyapatite, and CPP-ACP combined with fluoride—on artificially demineralized human enamel. Researchers applied each agent twice daily for 14 days, then evaluated enamel recovery using microhardness testing and elemental analysis to determine which formula most effectively restored lost minerals.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Healthy extracted third molars

• Teeth free from visible cracks or damage

• Properly stored in saline post-extraction

Exclusion Criteria:

• Teeth with pre-existing structural damage or defects

• Improperly prepared enamel surfaces

Demographics and Group Design

• Total samples: 33 human third molars

• Group allocation:

  • MI Varnish®: n = 11

  • 3M™ Clinpro™ White Varnish: n = 11

  • Megasonex®: n = 11

• One sample per group was reserved for SEM/EDS analysis

Primary Outcome Variable Results

Microhardness Results (HV0.1)

Statistical Findings:

• Significant improvement in microhardness in the MI Varnish® group vs. the other two (p = 0.001 for both).

• No significant difference between 3M™ Clinpro™ and Megasonex® groups (p = 0.97).

• Initial enamel hardness did not influence final outcomes (Pearson r = –0.301, p = 0.106).

Conclusions

The study concluded that MI Varnish®, containing both CPP-ACP and fluoride, showed the greatest remineralization efficacy, significantly outperforming both fluoride-only and nano-hydroxyapatite products. The combined release of calcium, phosphate, and fluoride from MI Varnish® likely contributed to its superior performance.

Discussion: Strengths and Limitations

Strengths:

• Utilized gold-standard methods: Vickers microhardness testing and SEM/EDS.

• Direct comparison of three distinct types of remineralizing agents.

• Controlled demineralization environment ensured uniformity.

Limitations:

• In vitro model lacks real-world oral conditions like saliva buffering, pH cycling, or bacterial activity.

• Short treatment duration (14 days) may not reflect long-term outcomes.

• Small sample size (n = 11 per group).

SEM/EDS Analysis Highlights:

• SEM revealed uneven enamel surfaces post-remineralization.

• EDS showed greatest mineral recovery in MI Varnish® group, confirming calcium, phosphate, and fluoride retention.

Citation

Salinovic I, Schauperl Z, Marcius M, Miletic I. The Effects of Three Remineralizing Agents on the Microhardness and Chemical Composition of Demineralized Enamel. Materials. 2021;14(20):6051.
PubMed Link: https://pubmed.ncbi.nlm.nih.gov/

Visual Aid: Microhardness Recovery Chart

Microhardness Recovery After 14 Days (Higher is Better)