Marco Lelli

Surface enamel remineralization: biomimetic apatite nanocrystals and fluoride ions different effects

A new method for altered enamel surface remineralization has been proposed. To this aim carbonate-hydroxyapatite nanocrystals which mimic for composition, structure, nanodimensions, and morphology dentine apatite crystals and resemble closely natural apatite chemical-physical properties have been used The results underline the differences induced by the use of fluoride ions and hydroxyapatite nanocrystals in contrasting the mechanical abrasions and acid attacks to which tooth enamel is exposed. Fluoride ions generate a surface modification of the natural enamel apatite crystals increasing their crystallinity degree and relative mechanical and acid resistance. On the other hand, the remineralization produced by carbonate-hydroxyapatite consists in a deposition of a new apatitic mineral into the eroded enamel surface scratches. A new biomimetic mineral coating, which progressively fills and shadows surface scratches, covers and safeguards the enamel structure by contrasting the acid and bacteria attacks.

Synthetic Biomimetic Carbonate-Hydroxyapatite Nanocrystals for Enamel Remineralization

New biomimetic carbonate-hydroxyapatite nanocrystals (CHA) have been designed and synthesized in order to obtain a remineralization of the altered enamel surfaces. Synthesized CHA mimic for composition, structure, nano dimension and morphology bone apatite crystals and their chemical-physical properties resemble closely those exhibited by enamel natural apatite. CHA can chemically bound themselves on the surface of natural enamel apatite thanks to their tailored biomimetic characteristics. The remineralization effect induced by CHA represents a real new deposition of carbonate-hydroxyapatite into the eroded enamel surface scratches forming a persistent biomimetic mineral coating, which covers and safeguards the enamel structure. The experimental results point out the possibility to use materials alternative to fluoride compounds which is commonly utilized to contrast the mechanical abrasions and acid attacks. The apatitic synthetic coating is less crystalline than enamel natural apatite, but consists of a new biomimetic apatitic mineral deposition which progressively fills the surface scratches. Therefore the application of biomimetic CHA may be considered an innovative approach to contrast the acid and bacteria attacks.

Recent Advancements in Preventing Teeth Health Hazard: The Daily Use of Hydroxyapatite Instead of Fluoride

Hydroxyapatite (HA) is commonly considered the most promising synthetic biomaterial for biomedical applications in orthopaedic, dental and maxillofacial surgery for its biocompatibility, bioresorption and bioactivity. Only recently a chemical-physical experimental approach has been utilized to investigate the capability of synthetic carbonated hydroxyapatite nanocrystals (CHA) to produce in vivo biomimetic mineral deposition on enamel and dentine surface through a daily use. Demineralised enamel and dentine slabs have been treated in vitro with synthetic biomimetic hydroxyapatite nanocrystals for a few minutes. This induced a surface remineralisation, forming a biomimetic apatite coating on enamel and dentine surface. In fact, enamel remineralisation quickly occurs thanks to the specific chemicalphysical characteristics of innovative nanostructured hydroxyapatite particles which closely resemble mineral enamel constituents. Therefore the experimental results suggest the possibility to perform teeth wear-deterioration prevention. Carbonated hydroxyapatite nanocrystals synthesized with tailored biomimetic characteristics for composition, structure, size and morphology can chemically bind themselves on the surfaces of teeth hard tissues, filling the scratches, producing a bound biomimetic apatitic coating, protecting the enamel surface structure. Over the past few decades many products for dental damage prevention (toothpastes, rinses and gels) have been commercialized and patented expressly for the fluoride remineralisation effect. Only recently the numerous applications of hydroxyapatite as bone filler biomaterial for implantation surgery have evidenced innovative and important opportunities for decay prevention through a daily use of oral care products containing hydroxyapatite. The aim of this paper is to review these recent patents and classify them according to their actual possibilities to safeguard

Remineralization and repair of enamel surface by biomimetic Zn-carbonate hydroxyapatite containing toothpaste: a comparative in vivo study

Consumption of acidic foods and drinks and other factors that cause enamel wear are responsible for the daily enamel loss and degradation. Use of some toothpastes that have been showed to possess different properties of remineralisation and/or repair of the enamel surface may help to protect tooth enamel. The aim of this study was to evaluate whether the use of toothpaste containing Zn-carbonate hydroxyapatite (CHA) nanostructured microcrystals may exert remineralization/repair effects of the enamel surface. Two groups of patients, aged between 18 and 75 years, used a Zn-CHA nanocrystals-based toothpaste (experimental group) and a potassium nitrate/sodium fluoride toothpaste (active control group) for 8 weeks. At the end of this period, extractions were performed in five subjects per study group. Negative controls consisted of two subjects treated with non-specified fluoride toothpaste. Teeth were processed for morphological and chemical-physic superficial characterizations by means of Scanning Electronic Microscopy with Elementary analysis, X-Ray Diffraction analysis and Infrared analysis. In this study, the use of a Zn-CHA nanocrystals toothpaste led to a remineralization/repair of the enamel surface, by deposition of a hydroxyapatite-rich coating. On the other hand, the use of both a nitrate potassium/sodium fluoride and non-specified fluoride toothpastes did not appreciably change the enamel surface. In conclusion, this study demonstrates that the toothpaste containing Zn-CHA nanostructured microcrystals, differently from nitrate potassium/sodium fluoride and non-specified fluoride toothpastes, may promote enamel superficial repair by means of the formation of a protective biomimetic CHA coating.

Different corrosive effects on hydroxyapatite nanocrystals and amine fluoride-based mouthwashes on dental titanium brackets: a comparative in vitro study.

Titanium plates treated in vitro with a mouthwash containing amine fluoride (100 ppm F−) and another containing zinc-substituted carbonate–hydroxyapatite have been analyzed by scanning electron microscopy and atomic force microscopy to evaluate the modification of the surface roughness induced by treatment with these two different mouthwashes. The treatment with F−-based mouthwash produces a roughness characterized by higher peaks and deeper valleys in the streaks on the titanium bracket surface compared with those observed in the reference polished titanium plates. This effect causes a mechanical weakness in the metallic dental implant causing bacterial growth and therefore promotes infection and prosthesis contamination. However, the in vitro treatment with a mouthwash containing zinc-substituted carbonate–hydroxyapatite reduced the surface roughness by filling the streaks with an apatitic phase. This treatment counteracts the surface oxidative process that can affect the mechanical behavior of the titanium dental implant, which inhibits the bacterial growth contaminating prostheses.

Biological activity of lactoferrin-functionalized biomimetic hydroxyapatite nanocrystals

The emergence of bacterial strains resistant to antibiotics is a general public health problem. Progress in developing new molecules with antimicrobial properties has been made. In this study, we evaluated the biological activity of a hybrid nanocomposite composed of synthetic biomimetic hydroxyapatite surface-functionalized by lactoferrin (LF-HA). We evaluated the antimicrobial, anti-inflammatory, and antioxidant properties of LF-HA and found that the composite was active against both Gram-positive and Gram-negative bacteria, and that it modulated proinflammatory and anti-inflammatory responses and enhanced antioxidant properties as compared with LF alone. These results indicate the possibility of using LF-HA as an antimicrobial system and biomimetic hydroxyapatite as a candidate for innovative biomedical applications.

Adsorption of the cis-[Pt(NH3)2(P2O7)]2 − (phosphaplatin) on hydroxyapatite nanocrystals as a smart way to selectively release activated cis-[Pt(NH3)2Cl2] (cisplatin) in tumor tissues

The relevant adsorption of cis-[Pt(NH3)2(P2O7)](2-) (phosphaplatin) on hydroxyapatite nanocrystals (nHAP) was observed and studied in water suspension. Phosphaplatin cytotoxicity, which is very low for HeLa, MCF-7 and HS-5 cell lines could be enhanced, reaching that of cisplatin, by interaction with solid nHAP. This effect stems from nHAP ability to catalyze the phosphaplatin hydrolysis, producing the same hydrolytic species responsible for cisplatin antitumor activity.

Metalated nucleotide chemisorption on hydroxyapatite

The experiments here reported evidence on the importance of the residual charge of a nucleotide derivative, for the adsorption on nHAP (hydroxyapatite nanocrystals), in water solution. We found that the simple presence of phosphates on the nucleotide derivative does not guarantee adsorption on nHAP. On the other hand, we demonstrated that a cationic or neutral charge on a nucleotide derivative produces a strongly reduced chemical adsorption (chemisorption) whereas, in the presence of a net negative charge, relevant adsorption on nHAP is observed. The number of phosphates can only modulate the adsorption efficiency of a molecule provided that this latter bears an overall negative charge. The neutral zwitterionic nucleotide Pt(II) complexes, bearing negatively charged phosphates, are unable to give stable chemisorption. Previous considerations are important to model the binding ability of phosphate bearing nucleotide derivatives or molecules on hydroxyapatite. The findings reported in the present paper could be relevant in bone tissue targeting or nHAP mediated drug delivery.

Lactoferrin Adsorbed onto Biomimetic Hydroxyapatite Nanocrystals Controlling - In Vivo - the Helicobacter pylori Infection

Background The resistance of Helicobacter pylori to the antibiotic therapy poses the problem to discover new therapeutic approaches. Recently it has been stated that antibacterial, immunomodulatory, and antioxidant properties of lactoferrin are increased when this protein is surface-linked to biomimetic hydroxyapatite nanocrystals. Objective Based on these knowledge, the aim of the study was to investigate the efficacy of lactoferrin delivered by biomimetic hydroxyapatite nanoparticles with cell free supernatant from probiotic Lactobacillus paracasei as an alternative therapy against Helicobacter pylori infection. Methods Antibacterial and antinflammatory properties, humoral antibody induction, histopathological analysis and absence of side effects were evaluated in both in vitro and in vivo studies. Results The tests carried out have been demonstrated better performance of lactoferrin delivered by biomimetic hydroxyapatite nanoparticles combined with cell free supernatant from probiotic Lactobacillus paracasei compared to both lactoferrin and probiotic alone or pooled. Conclusion These findings indicate the effectiveness and safety of our proposed therapy as alternative treatment for Helicobacter pylori infection.

In Vitro Comparison of Three Desensitizing Prophylaxis Pastes: AMorphological Analysis

Background and Objective: Dentine hypersensitivity (DH) characterizes for short sharp pain arising from exposed dentine. Nowadays, there is a vast choice of products to overcome it. The aim of the present observational study was to compare the efficacy of three prophylaxis pastes in occluding dentinal tubules from in an in vitro setting. Methods: Longitudinal mesio-distal sections were obtained from a sample of ten extracted teeth. Morphological analysis with scanning electron microscopy (SEM) assessed the penetration of three different prophylaxis pastes in dentinal tubules: Nupro by GSK, Stomyprox by Biorepair, Colgate Pro-Sollievo. The use of the Energy Dispersive X-ray Analysis (EDX probe) allowed assessing the exact composition of each product. Results: The SEM analysis revealed that only Stomyprox by Biorepair could penetrate the dentinal tubule due to its low crystallinity. Its small sized particles (˜1.60 μ) fit better the tubules lumen if compared to the other two pastes with higher sized granules. The small sample size and the lacking of a quantitative evaluation of tubules filling limit this result. Conclusion: The occlusion of dentinal tubules is one of the possible ways to reduce dentine hypersensitivity in a professional setting. Small sized particles fit better the lumen of tubules. In conclusion, there is a biological rationale in preferring prophylaxis pastes characterized by a low crystallinity. It is worthy to investigate furthermore, and in a clinical setting, the efficacy of the prophylaxis paste made by small sized particles of Hydroxyapatite.