Remineralization Induced by Biomimetic Hydroxyapatite Toothpastes on Human Enamel

Published In: Biomimetics
Publication Year: 2023

Study Design

This is an in vitro experimental study that evaluates the effects of four biomimetic hydroxyapatite-based toothpastes on enamel remineralization. The researchers used atomic force microscopy (AFM) and other analytical techniques to assess enamel surface properties before and after treatment.

Funding Sources

The research was funded by the Ministry of Research, Innovation and Digitization, CNCS/CCCDI-UEFISCDI, through project PN-III-P4-ID-PCE-2020-1910 (Project No. 186).

PICO Framework – What Was Studied and How?

Population:
Extracted third molars from healthy adults, demineralized artificially.

Intervention:
Application of four experimental biomimetic toothpastes containing various forms of hydroxyapatite (HAP, and substituted HAPs).

Comparison:
No treatment (negative control) and natural untreated enamel (positive control).

Outcomes:
Changes in enamel surface roughness (Ra), assessed through AFM after 10 days of treatment.

In Paragraph Form:

This study examined artificially demineralized enamel slices from extracted healthy third molars. The enamel slices were treated with one of four experimental hydroxyapatite toothpastes—each containing pure or multi-ion-substituted hydroxyapatite. The effectiveness of each formulation was compared to untreated demineralized enamel and natural enamel, with surface roughness as the primary outcome measure for enamel remineralization.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Healthy third molars extracted for orthodontic purposes

• No cracks, hypoplastic or carious lesions, or restorations

Exclusion Criteria:

• Teeth with pre-existing damage, restorations, or visible enamel flaws

Demographics and Sample Design

• Total number of enamel slices: 36

  • Control (natural enamel): 6

  • Negative control (demineralized, untreated): 6

  • Treatment groups (P1–P4): 6 slices per group (24 total)

Each slice underwent a 10-day treatment cycle involving brushing twice daily with a specific toothpaste (P1–P4), followed by analysis.

Primary Outcome Variables and Results

Primary Outcome: Surface roughness (Ra), measured using AFM.

• Statistical Significance: One-way ANOVA with Bonferroni’s test showed P2 and P3 groups significantly improved roughness compared to NC and even comparable or better than natural enamel.

• Particle Sizes: Toothpastes with smaller HAP nanoparticles (~30–37 nm) were more effective.

Conclusions

The study concluded that P2 (pure HAP) and P3 (HAP with Mg-Zn-Sr-Si) toothpastes demonstrated the highest remineralization efficiency, closely mimicking the structure and smoothness of natural enamel. These biomimetic formulations could be effective in treating early-stage enamel demineralization and preventing progression to caries.

Discussion: Strengths and Limitations

Strengths:

• High-resolution surface analysis using AFM

• Use of naturally extracted human enamel for realistic modeling

• Comparative analysis of different ion-substituted HAPs

Limitations:

• In vitro setting: Does not fully replicate the oral environment (e.g., salivary flow, bacteria, pH cycles)

• Short duration (10 days): Long-term effectiveness and clinical application need further study

Future Directions:

• Personalization of formulations based on enamel condition

• Incorporation of antimicrobial or anti-inflammatory agents

• Long-term in vivo studies to assess clinical relevance

Citation

Florea A-D, Pop LC, Benea H-R-C, et al. Remineralization Induced by Biomimetic Hydroxyapatite Toothpastes on Human Enamel. Biomimetics. 2023;8(6):450.
PubMed Link: https://pubmed.ncbi.nlm.nih.gov/

Visual Aid

Simple Chart: Enamel Surface Roughness After 10 Days