Nano Hydroxyapatite-Silica with a Core-Shell Structure for Long-Term Management of Dentin Hypersensitivity

Published In: iScience
Publication Year: 2024

Study Design

This study was an in vitro controlled experiment designed to evaluate the long-term effects of a novel material, nano hydroxyapatite-silica (nHASi), on dentin hypersensitivity. The researchers simulated oral conditions to assess dentin tubule occlusion, acid resistance, ion release, and odontogenic potential.

Funding Sources

This study was supported by the following grants and institutions:

• National Natural Science Foundation of China (82271036, 82201133, 82222015, 82171001)

• Young Elite Scientist Sponsorship Program by CAST (2022QNRC001)

• West China School/Hospital of Stomatology (RCDWJS2023-1)

• Fundamental Research Funds for the Knowledge Innovation Program of Wuhan (2022020801010085)

• Stomatological Hospital, Southern Medical University (PY2021008)

PICO Framework – what was studied and how?

Population:
Extracted human teeth (aged 18–25) and human dental pulp stem cells (DPSCs).

Intervention:
Application of nano hydroxyapatite-silica (nHASi) particles in fluoride toothpaste.

Comparison:

• Fluoride toothpaste alone (F)

• Fluoride toothpaste with nano hydroxyapatite (F + nHA)

• Commercial desensitizing toothpaste with bioactive glass (SEN)

Outcomes:

• Dentin tubule occlusion rate

• Resistance to acidic erosion

• Ion release and remineralization potential

• Cytocompatibility and odontogenic differentiation

In Paragraph Form:
This study evaluated the ability of a newly developed nano hydroxyapatite-silica (nHASi) material to address dentin hypersensitivity. Researchers tested the material’s ability to seal dentin tubules, resist acidic damage, and promote tooth remineralization and dental pulp stem cell differentiation compared to traditional ingredients like fluoride, nano hydroxyapatite, and bioactive glass.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Extracted healthy human teeth from 10 male and 10 female donors (ages 18–25)

• Human dental pulp stem cells (DPSCs) from established cell lines

Exclusion Criteria:

• No explicit exclusions listed, but likely excluded structurally compromised dentin or non-viable cells

Demographics and Study Design

Subjects:

• 40 dentin sheets used for testing

• 20 teeth (from 10 males, 10 females)

Groups:

• F: Fluoride toothpaste

• SEN: Commercial anti-sensitivity toothpaste (bioactive glass)

• F + nHA: Fluoride toothpaste with nano hydroxyapatite

• F + nHASi: Fluoride toothpaste with nano hydroxyapatite-silica

Test Duration:
3 and 5 days of cyclic demineralization/remineralization

Primary Outcome Variables and Results

Dentin Tubule Occlusion (after 5 days)

Additional Findings:

• Acid Resistance:

  • nHASi withstood 1% citric acid treatment significantly better than nHA.

  • nHA dissolved nearly completely; nHASi maintained structure and released calcium phosphate for remineralization.

• Ion Release:

  • nHASi released calcium, phosphate, and silicate ions steadily in artificial saliva for 7 days.

  • Silicate ions promoted mineralization and were not released in acidic conditions, indicating stability.

• Biocompatibility and Odontogenic Inductivity:

  • Both nHA and nHASi showed good cytocompatibility with dental pulp stem cells (DPSCs).

  • nHASi induced significantly greater expression of odontogenic markers DMP-1 and DSPP.

  • Alizarin red staining showed more robust calcium nodule formation with nHASi.

Conclusions

Nano hydroxyapatite-silica (nHASi) significantly improves dentin tubule occlusion, maintains structural integrity under acidic conditions, and promotes long-term remineralization and dentin repair. Its biocompatibility and ability to stimulate odontoblast-like cell differentiation make it a promising material for sustained management of dentin hypersensitivity.

Discussion: Strengths and Limitations

Strengths:

• Simulates oral environment with cyclic acid and saliva exposure

• Multiple comparative controls (fluoride, nHA, commercial toothpaste)

• Robust imaging and quantification methods (SEM, TEM, XRD, FTIR)

• Validated biological effects using human dental stem cells

Limitations:

• In vitro study only; no in vivo validation

• Difficulty applying the material in animal models due to challenges with anesthesia and repeated brushing

• Clinical translation will require future human trials

Citation

Wang Y, Chen S, Zhang M, Chen L, Zhou C, Tan S. Nano hydroxyapatite-silica with a core-shell structure for long-term management of dentin hypersensitivity. iScience. 2024 Dec 20;27:111474.
PubMed: https://pubmed.ncbi.nlm.nih.gov/

Visual Aids

Simple Chart: Dentin Tubule Occlusion Rate (5-Day Treatment)