Evaluation of remineralization potential and cytotoxicity of a novel strontium-doped nanohydroxyapatite paste: An in vitro study

The effect of nano-hydroxyapatite on white spot lesions: A systematic review and meta-analysis

OBJECTIVES

To assess the effect of nano-hydroxyapatite (nano-HAP) either with or without fluoride on white spot lesions (WSLs) in terms of remineralisation and colour change.

DATA SOURCES

An electronic search was carried out in MEDLINE via PubMed, Scopus, Web of Science, LILACS, Embase, Cochrane Library, Google Scholar, Grey literature, and hand search. There were no limitations in terms of language and date (till August 2024) and all studies meeting the inclusion criteria were included. The outcome variables were enamel surface microhardness, enamel remineralisation rate, mineral content, and colour change. Different risk of bias tools were employed according to the study design. The level of evidence was graded using the GRADE profiler.

STUDY SELECTION

A total of 14 out of 422 studies met the inclusion criteria. Three out of 14 studies were in vivo, one was in situ, while ten of them were in vitro. All 14 studies investigated the nano-HAP effects on WSLs. Following the full-text reviews and statistical analysis, 12 out of 14 studies were only included in the meta-analysis, since the remaining two studies lacked comparable data (mean±SD).

RESULTS

Different forms of delivery for nano-HAP were reported in the included studies. Pure nano-HAP showed promising effects on enamel surface microhardness (MD = 9.29, 95 % CI [7.74, 10.84], p < 0.00001), and mineral gain (MD = 0.09, 95 % CI [0.05, 0.13], P < 0.0001) when compared to fluoride alone. In addition, nano-HAP and fluoride demonstrated similar remineralisation abilities based on the DIAGNOdent™ readings (MD=0.09, 95 % CI [0.05, 0.13], p < 0.0001) There were no colour improvements within the WSLs following the application of nano-HAP (MD = -2.76, 95 % CI [-6.79, 1.27], p = 0.18).

CONCLUSION

The intervention containing pure nano-HAP showed a promising remineralisation effect on WSLs in comparison to fluoride alone. However, there were no colour changes within WSLs following the use of nano-HAP. Limited number of clinical studies, high risk of bias, quality of the available studies, and relatively short follow-up periods failed to result in concrete evidence.

CLINICAL SIGNIFICANCE

The intervention containing pure nano-HAP showed a promising remineralisation effect in comparison to fluoride alone. Therefore, it might be an effective alternative to fluoride-containing agents.

In Vitro Models Used in Cariology Mineralisation Research-A Review of the Literature

BACKGROUND

Dental caries remains a significant global health problem. One of the fundamental mechanisms underlying the development and progression of dental caries is the dynamic process of demineralisation/remineralisation. In vitro models have played a critical role in advancing our understanding of this process and identifying potential interventions to prevent or arrest dental caries. This literature review aims to provide a structured oversight of in vitro mineralisation models which have been used to study the tooth demineralisation/remineralisation process.

METHODS

Publications from 2019 to 2023 were screened to identify articles reporting the use of in vitro models to study the demineralisation/remineralisation of tooth caries. The included studies were methodologically assessed for their information on (i) substrate, (ii) lesion formation, and (iii) mineralisation models.

RESULTS

The most reported substrates used in the studies were human teeth along with bovine incisors. Acetic/lactic buffers were the most common solutions to induce caries lesions. pH cycling was the most frequently used mineralisation model for simulating the daily change within the oral environment. This review discussed the advantages and limitations of various approaches.

CONCLUSIONS

Standardisation of in vitro mineralisation models is crucial for enabling effective comparison between studies and advancing caries research.

Applications of Bioactive Strontium Compounds in Dentistry

Divalent cations have captured the interest of researchers in biomedical and dental fields due to their beneficial effects on bone formation. These metallic elements are similar to trace elements found in human bone. Strontium is a divalent cation commonly found in various biomaterials. Since strontium has a radius similar to calcium, it has been used to replace calcium in many calcium-containing biomaterials. Strontium has the ability to inhibit bone resorption and increase bone deposition, making it useful in the treatment of osteoporosis. Strontium has also been used as a radiopacifier in dentistry and has been incorporated into a variety of dental materials to improve their radiopacity. Furthermore, strontium has been shown to improve the antimicrobial and mechanical properties of dental materials, promote enamel remineralization, alleviate dentin hypersensitivity, and enhance dentin regeneration. The objective of this review is to provide a comprehensive review of the applications of strontium in dentistry.

Remineralization potential of strontium-doped nano-hydroxyapatite dentifrice and casein phosphopeptide-amorphous calcium phosphate cream on white spot lesions in enamel following orthodontic debonding - a randomized controlled trial

Aim and Objective

This study was intended to compare and determine the potency of strontium-doped nano-hydroxyapatite paste against a topical cream containing casein phosphopeptide-amorphous calcium phosphate and a regular dentifrice for remineralization of white spot lesions of enamel following orthodontic debonding.

Methods

Ninety individuals with white spot lesions on their enamel who visited the orthodontic department for de-bonding were selected for the research. Patients were randomly assigned to three distinct groups with each group consisting of 30 patients. Group 1 served as the control and received regular dentifrice, Group 2 received strontium-doped nano-hydroxyapatite paste, and Group 3 received casein phosphopeptide-amorphous calcium phosphate topical cream. Patients were instructed to locally apply a specified amount of the prescribed preparation twice daily for six weeks. The data were analysed using the statistical programme SPSS 22.0 (SPSS Inc., Chicago, IL, USA), and the level of significance had been set at p < 0.05.

Results

Group 1 did not show any change in the enamel following the application of toothpaste. Both Group 2 and 3 demonstrated higher post-treatment scores, indicating effective remineralization potential (p < 0.001). However, Group 2 (strontium-doped nano-hydroxyapatite paste) displayed significantly greater remineralization capacity when compared to group 3 (casein phosphopeptide-amorphous calcium phosphate topical cream).

Conclusion

Compared to conventional dentifrice and casein phosphopeptide-amorphous calcium phosphate paste, strontium-doped nano-hydroxyapatite preparation demonstrated greater enamel remineralization of the white spot lesions and favourable surface alterations in the enamel surface. strontium-doped nano-hydroxyapatite can be utilised safely and efficiently to treat early caries and remineralise white spot lesions on the enamel.

Remineralization Induced by Biomimetic Hydroxyapatite Toothpastes on Human Enamel

This work aimed to compare the effect of four new toothpastes (P1-P4) based on pure and biomimetic substituted nano-hydroxyapatites (HAPs) on remineralization of human enamel. Artificially demineralized enamel slices were daily treated for ten days with different toothpastes according to the experimental design. Tooth enamel surfaces were investigated using atomic force microscope (AFM) images and surface roughness (Ra) determined before and after treatment. The surface roughness of enamel slices was statistically analyzed by one-way ANOVA and Bonferroni's multiple comparison test. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data revealed the HAP structure with crystal sizes between 28 and 33 nm and crystallinity between 29 and 37%. The average size of HAP particles was found to be between 30 and 40 nm. The Ra values indicated that P3 (HAP-Mg-Zn-Sr-Si) toothpaste was the most effective after 10 days of treatment, leading to the lowest mean roughness. The P3 and P2 (HAP) toothpastes were found to be effective in promoting remineralization. Specifically, their effectiveness can be ranked as follows: P3 = P2 > P4 (HAP-Mg-Zn-Si) > P1 (HAP-Zn), considering both the chemical composition and the size of their constitutive nanoparticles. The proposed toothpastes might be used successfully to treat early tooth decay.

A Systematic Review on the Effect of Strontium-Doped Nanohydroxyapatite in Remineralizing Early Caries Lesion

The aim of this study is to review the potential of strontium-doped nanohydroxyapatite (SrnHAP) as a biomaterial for remineralizing early carious lesions. Publications from 2012 to 2022 were included based on the patient/population, intervention, comparison, and outcomes (PICO) framework, focusing on demineralized enamel treated with strontium-doped nanohydroxyapatite compared to other remineralizing agents, with the primary outcome being remineralization capacity. Electronic databases, namely, PubMed, Cochrane Library, and Google Scholar, were explored from March 31, 2023, to April 10, 2023. Only English language studies were included, while certain research types and studies on bovine teeth were excluded. Bias was assessed using the Cochrane methodology. Five studies were synthesized, all using extracted human maxillary premolars. Four studies focused on remineralizing enamel, while one study focused on remineralizing dentin. Among these studies, comparisons were made between different strontium concentrations and various remineralizing agents such as nanohydroxyapatite (nHAP), Acclaim, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and NovaMin. X-ray diffraction analysis was used to examine hydroxyapatite formation, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization. Additionally, one study evaluated the mechanical properties of partially demineralized dentin specimens. This study was registered in the PROSPERO under the ID CRD42023397413 and completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Nano-Hydroxyapatite (nHAp) in the Remineralization of Early Dental Caries: A Scoping Review

(1) Background: Nano-hydroxyapatite (nHAp) has been reported to have a remineralizing effect on early carious lesions. The objective of this scoping review was to analyze the remineralization potential of nano-hydroxyapatite (nHAp)-containing dentifrices, by mapping the existing literature. (2) Methods: This review was performed using the PRISMA-ScR Checklist, which is an extension of the PRISMA Checklist for Systematic Reviews and Meta-Analyses. In this study, the population, concept, and context (PCC) framework was used to find relevant papers published between 2010 and 2021. Nano-hydroxyapatite (nHAp) and dentifrices containing nHAp as one of the ingredients were the two main concepts of the research question. MeSH phrases, keywords, and other free terms relevant to nano-hydroxyapatite and dentifrices were used to search the literature databases. (3) Results: Preliminary searches yielded 59 studies; the title and abstract screening results excluded 11 studies. The remaining studies were thoroughly reviewed by two reviewers on the basis of the inclusion and exclusion criteria. Finally, 28 studies were included, and 20 studies were excluded. Most of the studies that were included reported that when nHAp was used alone, it had many different effects, such as remineralization, caries prevention, less demineralization, brighter teeth, less pain, and remineralization of enamel after orthodontic debonding. (4) Conclusions: Dentifrices that contain nHAp offer a variety of therapeutic and preventative effects. Currently, there is insufficient evidence to support the efficacy of nHAp dentifrices in primary teeth. Additional long-term investigations using standardized protocols are required to reach decisive conclusions about the effects of nHAp dentifrices on primary and permanent dentitions.