Synthesis of stabilized hydroxyapatite nanosuspensions for enamel caries remineralization

The Deposition of Hydroxyapatite Particles Within an Organic Matrix on the Surface of Poly(lactic acid)

Hydroxyapatite (HAP) is a well-established material in biomedical applications, especially for bone tissue regeneration, dental implants, and drug delivery systems. Recent research emphasizes enhancing the biocompatibility and osteoconductivity of orthopedic implants using HAP. This study explores the potential of combining HAP with a lipid matrix to improve the surface properties and biocompatibility of poly(lactic acid) (PLA)-based, 3D-printed, resorbable bone implants. We utilized the Langmuir-Blodgett method to deposit HAP within a dihexadecyl phosphate (DHP) matrix onto PLA substrates. This study demonstrates that DHP and HAP form stable monolayers at the air/water interface with HAP particles distributed within a homogeneous lipid matrix. The presence of HAP and the resulting changes in surface free energy (SFE) are hypothesized to enhance the biocompatibility of PLA implants. Our findings indicate that films composed of DHP + HAP 5:1 are particularly effective in altering PLA surface characteristics, potentially improving osteointegration, and reducing microbial adherence. Overall, this work highlights that surface modification of PLA with HAP and lipid matrices is the first step towards new, promising, and cost-effective strategies for developing advanced biomaterials for bone regeneration.

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.

Ceramic Nanomaterials in Caries Prevention: A Narrative Review

Ceramic nanomaterials are nanoscale inorganic metalloid solids that can be synthesised by heating at high temperatures followed by rapid cooling. Since the first nanoceramics were developed in the 1980s, ceramic nanomaterials have rapidly become one of the core nanomaterials for research because of their versatility in application and use in technology. Researchers are developing ceramic nanomaterials for dental use because ceramic nanoparticles are more stable and cheaper in production than metallic nanoparticles. Ceramic nanomaterials can be used to prevent dental caries because some of them have mineralising properties to promote the remineralisation of tooth tissue. Ceramic minerals facilitate the remineralisation process and maintain an equilibrium in pH levels to maintain tooth integrity. In addition, ceramic nanomaterials have antibacterial properties to inhibit the growth of cariogenic biofilm. Researchers have developed antimicrobial nanoparticles, conjugated ceramic minerals with antibacterial and mineralising properties, to prevent the formation and progression of caries. Common ceramic nanomaterials developed for caries prevention include calcium-based (including hydroxyapatite-based), bioactive glass-based, and silica-based nanoparticles. Calcium-based ceramic nanomaterials can substitute for the lost hydroxyapatite by depositing calcium ions. Bioactive glass-based nanoparticles contain surface-reactive glass that can form apatite crystals resembling bone and tooth tissue and exhibit chemical bonding to the bone and tooth tissue. Silica-based nanoparticles contain silica for collagen infiltration and enhancing heterogeneous mineralisation of the dentin collagen matrix. In summary, ceramic nanomaterials can be used for caries prevention because of their antibacterial and mineralising properties. This study gives an overview of ceramic nanomaterials for the prevention of dental caries.

Evaluation of the effects of different remineralisation agents on initial enamel lesions by scanning electron microscope and energy-distributed X-ray analysis

BACKGROUND

This study compared the ability of four remineralization agents to restore demineralised enamel lesions in permanent human incisors.

METHODS

In total, 40 teeth were included in the study. Two samples were obtained from each tooth. The 80 samples were divided into 10 groups (n = 8 per group). The right halves of the teeth were controls solely subjected to demineralisation and stored in artificial saliva for the duration of the experiment. The left halves of the teeth were remineralised using a 5% NaF-containing fluoride varnish (GC MI varnish; GC Corp.), a toothpaste containing casein phosphopeptide and amorphous calcium (GC tooth mousse; GC Corp.), a water-soluble remineralisation paste containing fluoride, hydroxyapatite, xylitol (Remin Pro; Voco), and ROCS remineralising gel containing Ca, magnesium(Mg) and phosphate (P). After 21 days of remineralisation, scanning electron microscopy and energy-dispersive X-ray (EDX) assessments were performed, and the results were analysed using one-way analysis of variance.

RESULTS

EDX analysis showed that the ROCS medical remineralising gel had the lowest Ca/P ratio among the groups (P = .04). Compared with the control groups, the Remin Pro and ROCS medical remineralising gel treatments produced significantly higher Ca/P ratios (P = .014 and P = .025). These results were statistically significant, and P-value <.05 was accepted for statistical significance.

CONCLUSIONS

The group treated with a fluoride-free, xylitol-containing ROCS medical remineralising gel had the lowest Ca/P ratio. Compared with the control groups, Remin Pro and ROCS remineralising gel appeared effective for repairing initial enamel lesions.