An In-vitro Comparison of Nano Hydroxyapatite, Novamin and Proargin Desensitizing Toothpastes – A SEM Study

Published In: Journal of Clinical and Diagnostic Research
Publication Year: 2016

Study Design

This was an in-vitro experimental study using extracted human teeth. Dentin discs were randomly allocated to three dentifrice groups and one saline control group. Outcomes were measured using scanning electron microscopy (SEM) to assess tubule occlusion.

Funding Sources

The authors reported no financial support and no conflicts of interest.

PICO Framework – what was studied and how?

Population
Extracted, caries-free human premolars and molars (40 in total), cut into 1 mm dentin discs.

Intervention
Daily application (2 minutes for 7 days) of dentifrice slurries containing:

• Nano-hydroxyapatite (n-HAp)

• Calcium sodium phosphosilicate (bioactive glass)

• Arginine + calcium carbonate + fluoride

Comparison
Control group treated with saline.

Outcomes
Percentage of completely occluded dentinal tubules assessed by SEM after 7 days.

In Paragraph Form
This study examined dentin discs from extracted human teeth, comparing nano-hydroxyapatite, calcium sodium phosphosilicate, and arginine with calcium carbonate (fluoride) dentifrices to a saline control. The primary outcome was the degree of dentinal tubule occlusion measured under SEM after one week of daily application.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Extracted premolars or molars from orthodontic extractions

• Caries-free surfaces

• Roots without erosion or abrasion

Exclusion Criteria:

• Endodontically treated teeth

• Teeth that had undergone scaling within the last 6 months

Demographics and Sample Setup

• Total sample: 40 dentin discs (10 per group)

• Groups:

  1. Saline control

  2. Nano-hydroxyapatite (n-HAp)

  3. Calcium sodium phosphosilicate

  4. Arginine + CaCO₃ + fluoride

• Duration: Daily 2-minute application × 7 days

• Evaluation: Pre- and post-treatment SEM imaging at 1000× magnification

Primary Outcome Variables and Results

Completely occluded dentinal tubules (%)

• Control (saline): 15.3%

• Nano-hydroxyapatite: 97.6%

• Calcium sodium phosphosilicate: 81.9%

• Arginine + CaCO₃ (+ fluoride): 65.4%

Statistical Findings

• ANOVA: F = 8.362, p = 0.005

• Bonferroni post-hoc tests:

  • n-HAp vs Arginine + CaCO₃: p = 0.005 (significant)

  • n-HAp vs Calcium sodium phosphosilicate: p = 0.235 (not significant)

  • Bioactive glass vs Arginine + CaCO₃: p = 0.154 (not significant)

Conclusions

All three active dentifrices produced significant dentinal tubule occlusion compared to control. Nano-hydroxyapatite was the most effective, significantly outperforming the arginine-based product and numerically outperforming calcium sodium phosphosilicate.

Discussion: Strengths and Limitations

Strengths

• Use of SEM imaging provided clear visualization of tubule occlusion

• Statistical rigor with ANOVA and Bonferroni adjustments

• Direct head-to-head comparison of three desensitizing technologies

Limitations

• In-vitro design — clinical sensitivity reduction was not measured

• Small sample size (n = 10 per group)

• Inconsistency in reported concentration of n-HAp (1% vs 15%)

• Short duration (7 days), no long-term durability testing

Citation

Kulal R, Jayanti I, Sambashivaiah S, Bilchodmath S. An In-vitro Comparison of Nano Hydroxyapatite, Novamin and Proargin Desensitizing Toothpastes – A SEM Study. J Clin Diagn Res. 2016;10(10):ZC51–ZC54. PMID: 27891458.
PubMed Link

Visual Aid

Dentinal Tubule Occlusion After 7 Days (Higher is Better)