Evaluation of the Remineralisation of the Demineralized Enamel Surrounding Orthodontic Brackets using the Nano Hydroxyapatite: An Original Study

Evaluation of the Remineralisation of the Demineralized Enamel Surrounding Orthodontic Brackets using the Nano Hydroxyapatite: An Original Study

Evaluation of the Remineralisation of the Demineralized Enamel Surrounding Orthodontic Brackets using the Nano Hydroxyapatite: An Original Study

Published In: Journal of Pharmacy and Bioallied Sciences
Publication Year: 2023

Study Design

This is an in vitro experimental study, evaluating the effects of nano-hydroxyapatite (nano-HAP) on demineralized enamel surrounding orthodontic brackets.

Funding Sources

No funding was declared.
Conflicts of interest: None reported.

PICO Framework – what was studied and how?

Population:
Extracted healthy human permanent premolars with orthodontic brackets (simulating demineralized enamel).

Intervention:
Application of two concentrations of nano-hydroxyapatite:

  • 20% nano-HAP varnish

  • 3% nano-HAP toothpaste with 1450 ppm sodium fluoride

Comparison:
Control group with no remineralization treatment.

Outcomes:

  • Mineral content (calcium and phosphorus levels)

  • Surface roughness (Ra)

  • Enamel color (∆L*, ∆a*, ∆b*, and ∆E*)

In paragraph form:
This study used extracted premolars with fixed orthodontic brackets to simulate real-life enamel demineralization. It tested whether nano-hydroxyapatite, in both varnish and toothpaste forms, could enhance enamel remineralization compared to a control group. The results were measured via mineral deposition (SEM-EDAX), enamel surface roughness (profilometer), and tooth color changes (spectrophotometer).

Inclusion and Exclusion Criteria

Inclusion Criteria:

  • Recently extracted healthy human permanent premolars

  • No caries or enamel anomalies

  • Extracted primarily for orthodontic purposes

Exclusion Criteria:

  • Teeth with caries, cracks, or visible anomalies

  • Teeth not extracted for orthodontic treatment

Demographics and Study Design

  • Total samples: 60 premolars

  • Divided into three groups (n=20 per group):

    • Group A (Control): No remineralization treatment

    • Group B (Varnish): Treated with 20% nano-HAP varnish

    • Group C (Toothpaste): Treated with 3% nano-HAP toothpaste + 1450 ppm fluoride

Primary Outcome Variables and Results

1. Mineral Deposition (Calcium and Phosphorus by EDAX)

After treatment:

  • Calcium (%)

    • Control: 24.85 ± 2.55

    • Varnish: 38.2 ± 7.08

    • Toothpaste: 31.29 ± 2.25

    • P-value: 0.001

  • Phosphorus (%)

    • Control: 12.02 ± 1.23

    • Varnish: 16.8 ± 0.46

    • Toothpaste: 14.62 ± 0.48

    • P-value: <0.001

2. Tooth Color Changes (Spectrophotometry)

Group ∆L* ∆a* ∆b* ∆E* (Total Color Change)
Control 0.0 ± 0.04 -0.01 ± 0.70 0.69 ± 0.47 0.69 ± 0.57
Varnish -4.57 ± 0.85 0.08 ± 0.12 1.65 ± 0.65 5.03 ± 1.01
Toothpaste -1.39 ± 3.0 0.07 ± 0.26 1.36 ± 0.69 4.15 ± 1.14
P-value <0.001 0.636 0.0236 <0.001


3. Surface Roughness (Ra)

Group Pre-Application (Ra) Post-Application (Ra) % Improvement P-value
Control 0.60 ± 0.05 0.68 ± 0.05 -1.11 ± 1.61 0.02
Varnish 0.59 ± 0.05 0.51 ± 0.04 -24.56 ± 3.03 <0.001
Toothpaste 0.56 ± 0.03 0.57 ± 0.03 -13.02 ± 1.80 <0.001

Conclusions

  • Nano-hydroxyapatite significantly enhances enamel remineralization, especially in areas demineralized due to fixed orthodontic appliances.

  • Both varnish and toothpaste forms were effective, with varnish showing slightly better mineral deposition and surface smoothness.

  • There were notable improvements in enamel color, making the treated enamel more aesthetically similar to healthy enamel.

Discussion: Strengths and Limitations

Strengths:

  • Multi-modal evaluation using SEM, EDAX, profilometry, and spectrophotometry

  • Quantitative assessment of mineral content and surface texture

  • Relevant simulation of orthodontic bracket-induced enamel demineralization

Limitations:

  • In vitro design – lacks saliva flow, oral microbiota, and patient-related variables

  • Short evaluation period

  • Toothpaste included fluoride, making it difficult to isolate nano-HAP effects

Citation

Samineni S, Rathore BS, Rohilla N, Varma PK, Niwlikar KB, Sarma SN. Evaluation of the remineralisation of the demineralized enamel surrounding orthodontic brackets using the nano hydroxyapatite: An original study. J Pharm Bioall Sci. 2023;15:S175-9.
📄 PubMed Link 

Visual Aid: Summary Chart of Primary Results

Outcome Control Group Varnish (20% nano-HAP) Toothpaste (3% nano-HAP + Fluoride)
Calcium (%) 24.85 ± 2.55 38.2 ± 7.08 31.29 ± 2.25
Phosphorus (%) 12.02 ± 1.23 16.8 ± 0.46 14.62 ± 0.48
Color Change (∆E)* 0.69 ± 0.57 5.03 ± 1.01 4.15 ± 1.14
Surface Roughness (Ra) 0.68 ± 0.05 0.51 ± 0.04 0.57 ± 0.03
Statistical Significance Baseline Significant (p < 0.001) Significant (p < 0.001)
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