EFFICACY OF NOVEL BIOACTIVE GLASS IN THE TREATMENT OF ENAMEL WHITE SPOT LESIONS: A RANDOMIZED CONTROLLED TRIAL✰.

OBJECTIVES: to evaluate the efficacy of 2 types of bioactive glass (45S5) compared to casein-phosphopeptide stabilized-amorphous calcium phosphate (CPP-ACP) in the treatment of orthodontically-induced white spot lesions (WSLs). METHODS: Sixty post-orthodontic WSLs (ICDAS II score 2) were randomly allocated to a double blind randomized controlled trial with 3 parallel arms (n = 20). Test group I (Bio-BAG) received BiominF slurry and toothpaste, and test group II (N-BAG) received Novamin slurry and toothpaste. While the positive control group (CPP-ACP) received Recaldent paste. Products were applied daily in-office during week 1, and boosted by self-administered home application for 4 weeks (week 1-4). Standard oral hygiene care was performed by all participants twice daily during months 2-6. All patients were assessed for change in WSL dimensions using computer assisted analysis based on standardized digital intraoral photographs in addition to laser fluorescence DIAGNOdent assessment before treatment (T0) and at 1 week (T1), 1 month (T2), 3 months (T3,) and 6 months (T4) follow up periods. RESULTS: Kruskal Wallis test was used (P < .05 for all). At T4, a statistically significant (P < .001) regression of WSL was disclosed in all 3 groups compared to baseline, and a highly significant lesion size percent reduction in Bio-BAG group compared to the control group (P < .001). The mean area of the lesions decreased by 64.8%, 32.2%, and 31.6% for groups I, II and III respectively (P = .001). DIAGNOdent findings largely reflected the clinical scores (Mean scores at baseline/T4 for groups I, II, and III respectively; 16.57/3.62, 16.93/7.90, 21.95/19.27). No adverse effects were reported. CONCLUSIONS: The combined in-office and home-application of BiominF paste for 4 weeks resulted in greater esthetic improvements of post-orthodontic WSLs compared to Novamin and CPP-ACP. In addition, BiominF showed a significant reduction in fluorescence intensity which indicates potential lesion remineralization. CLINICAL RELEVANCE: Post-orthodontic WSLs can be diminished using bioactive glass remineralization therapy.

Randomized investigation of the bioavailability of fluoride in saliva after administration of sodium fluoride, amine fluoride and fluoride containing bioactive glass dentifrices.

OBJECTIVES: Bioactive glasses which degrade in aqueous solutions may release bioactive ions such as fluoride (F-) and support fluoride bioavailability in saliva. We investigated how these effects would be apparent in an in vivo experimental trial after toothbrushing in comparison with sodium fluoride and amine fluoride. MATERIAL AND METHODS: In this single-center, randomized, parallel in vivo trial with a three strata block design, where healthy subjects were randomly assigned into three groups. Each group brushed their teeth either with fluoridated bioactive glass containing dentifrice, with a sodium fluoride (NaF) containing dentifrice or with amine fluoride (AmF) containing toothpaste. Saliva was collected time intervals before, immediately after, 30, 60 and 120 min after toothbrushing. Fluoride concentration was determined in supernatant saliva and salivary sediment using a fluoride ion selective electrode. The data were evaluated statistically using non-parametric tests. RESULTS: The increase of bioactive fluoride in supernatant saliva was higher after application of NaF or AmF compared to fluoridated bioactive glass. In salivary sediment bioavailability of fluoride lasted longer after application of fluoridated bioactive glass. CONCLUSIONS: Toothbrushing with the fluoride containing bioactive glass dentifrices had positive effects on the fluoride bioavailability within two hours. Fluoride containing bioactive glass represent a new area for investigation in caries prophylaxis. The bioactive potential impact on the tooth remineralization should be examined further. TRIAL REGISTRATION: DRKS00016038 .

Development of a novel bioactive glass for air-abrasion to selectively remove orthodontic adhesives.

OBJECTIVES: To develop a novel, bioactive glass for removing residual orthodontic adhesive via air-abrasion, following bracket debonding, and to evaluate its effectiveness against a proprietary bioactive glass 45S5(Sylc™)-air-abrasion, and a slow-speed tungsten carbide (TC) bur. MATERIALS AND METHODS: Three glasses were prepared and their bioactivity was proved. One novel glass (QMAT3) was selected due to its appropriate hardness, lower than that of enamel/45S5(Sylc™). Sixty extracted human premolars were randomly assigned to adhesive removal using: (a) QMAT3-air-abrasion, (b) 45S5(Sylc™)-air-abrasion, and (c) TC bur, which were further subdivided (n = 10) based on the adhesive used (Transbond XT™ or Fuji Ortho LC™). Enamel roughness was assessed using scanning electron microscopy (SEM) and non-contact profilometry before bracket bonding, after removing residual adhesive following bracket debonding and after polishing. RESULTS: QMAT3 formed apatite faster (6 h) than 45S5(Sylc™) (24 h) in Tris solution. QMAT3-air-abrasion gave the lowest enamel roughness (Ra) after removing the adhesives. SEM images showed a pitted, roughened enamel surface in the TC bur group and to a lesser extent with 45S5(Sylc™), while a virtually smooth surface without any damage was observed in the QMAT3-air-abrasion group. The time taken for adhesive removal with QMAT3 was comparable to 45S5(Sylc™) but was twice as long with the TC bur. CONCLUSIONS: QMAT3-air-abrasion is a promising technique for selective removal of adhesives without inducing tangible enamel damage. CLINICAL RELEVANCE: A novel bioactive glass has been developed as an alternative to the use of TC burs for orthodontic adhesive removal.

Strontium substituted bioactive glasses for tissue engineered scaffolds: the importance of octacalcium phosphate.

Porous bioactive glasses are attractive for use as bone scaffolds. There is increasing interest in strontium containing bone grafts, since strontium ions are known to up-regulate osteoblasts and down regulate osteoclasts. This paper investigates the influence of partial to full substitution of strontium for calcium on the dissolution and phase formation of a multicomponent high phosphate content bioactive glass. The glasses were synthesised by a high temperature melt quench route and ground to a powder of <38 microns. The dissolution of this powder and its ability to form apatite like phases after immersion in Tris buffer (pH 7.4) and simulated body fluid (SBF) was followed by inductively coupled plasma optical emission spectroscopy (ICP), Fourier transform infra red spectroscopy (FTIR), X-ray powder diffraction (XRD) and (31)P solid state nuclear magnetic resonance spectroscopy up to 42 days of immersion. ICP indicated that all three glasses dissolved at approximately the same rate. The all calcium (SP-0Sr-35Ca) glass showed evidence of apatite like phase formation in both Tris buffer and SBF, as demonstrated after 3 days by FTIR and XRD analysis of the precipitate that formed during the acellular dissolution bioactivity studies. The strontium substituted SP-17Sr-17Ca glass showed no clear evidence of apatite like phase formation in Tris, but evidence of an apatite like phase was observed after 7 days incubation in SBF. The SP-35Sr-0Ca glass formed a new crystalline phase termed "X Phase" in Tris buffer which FTIR indicated was a form of crystalline orthophosphate. The SP-35Sr-0Ca glass appeared to support apatite like phase formation in SBF by 28 days incubation. The results indicate that strontium substitution for calcium in high phosphate content bioactive glasses can retard apatite like phase formation. It is proposed that apatite formation with high phosphate bioactive glasses occurs via an octacalcium phosphate (OCP) precursor phase that subsequently transforms to apatite. The equivalent octa-strontium phosphate does not exist and consequently in the absence of calcium, apatite formation does not occur. The amount of strontium that can be substituted for calcium in OCP probably determines the amount of strontium in the final apatite phase and the speed with which it forms.

Abrasive wear of enamel by bioactive glass-based toothpastes.

PURPOSE: To determine the abrasivity of a 45S5 bioactive glass based toothpaste on enamel as a function of the particle size and shape of the glass. METHODS: 45S5 glass was synthesized ground and sieved to give various particle sized fractions < 38, 38-63 and 63-110 microns. Two different grinding routes were used: percussion milling and ball milling. The glass powders were formulated into toothpastes and their tooth brush abrasivity measured according to BS EN ISO11609 methodology. RESULTS: Enamel loss increased with increasing particle size. The percussion milled powder exhibited particles that had sharp edges and the pastes were significantly more abrasive than the pastes made with round ball milled powders. One interesting observation made during the present study was that there was preferential wear of the enamel at the dentin-enamel junction (DEJ), particularly with the coarse particle sized pastes.

Trends and perspectives on the commercialization of bioactive glasses.

At least 25 bioactive glass (BG) medical devices have been approved for clinical use by global regulatory agencies. Diverse applications include monolithic implants, bone void fillers, dentin hypersensitivity agents, wound dressing, and cancer therapeutics. The morphology and delivery systems of bioactive glasses have evolved dramatically since the first devices based on 45S5 Bioglass®. The particle size of these devices has generally decreased with the evolution of bioactive glass technology but primarily lies in the micron size range. Morphologies have progressed from glass monoliths to granules, putties, and cements, allowing medical professionals greater flexibility and control. Compositions of these commercial materials have primarily relied on silicate-based systems with varying concentrations of sodium, calcium, and phosphorus. Furthermore, therapeutic ions have been investigated and show promise for greater control of biological stimulation of genetic processes and increased bioactivity. Some commercial products have exploited the borate and phosphate-based compositions for soft tissue repair/regeneration. Mesoporous BGs also promise anticancer therapies due to their ability to deliver drugs in combination with radiotherapy, photothermal therapy, and magnetic hyperthermia. The objective of this article is to critically discuss all clinically approved bioactive glass products. Understanding essential regulatory standards and rules for production is presented through a review of the commercialization process. The future of bioactive glasses, their promising applications, and the challenges are outlined. STATEMENT OF SIGNIFICANCE: Bioactive glasses have evolved into a wide range of products used to treat various medical conditions. They are non-equilibrium, non-crystalline materials that have been designed to induce specific biological activity. They can bond to bone and soft tissues and contribute to their regeneration. They are promising in combating pathogens and malignancies by delivering drugs, inorganic therapeutic ions, and heat for magnetic-induced hyperthermia or laser-induced phototherapy. This review addresses each bioactive glass product approved by regulatory agencies for clinical use. A review of the commercialization process is also provided with insight into critical regulatory standards and guidelines for manufacturing. Finally, a critical evaluation of the future of bioactive glass development, applications, and challenges are discussed.

MgF2- containing glasses as a coating for titanium dental implant. I- Glass powder.

Bioactive glasses can be used to coat titanium implants to promote osseointegration. However, incorporating elements such as magnesium, zinc and fluoride into bioactive glasses might have a negative effect on bioactivity or the coefficient of thermal expansion of the glass. In this study, the impact of substituting MgO for CaO on physical properties and bioactivity of glass containing 1 mol % MgF2 was assessed. Seven glasses were produced by melt-quenched route. The glasses comprise (SiO2, CaO, Na2O, MgO, MgF2, K2O and P2O5) and were characterized utilizing XRD, DSC, FTIR and dilatometry analyses. The bioactivity of these glasses was investigated in biological fluids. The results showed that these glasses have wide sintering windows, low TECs and low glass transition and softening temperatures. The bioactive glasses containing up to 13.3 mol% MgO were able to form surface apatite within a short time period; whereas glasses containing ≥16.13 mol% demonstrated only structural variations with no clear sign of apatite precipitation.

Novel Fluoride- and Chloride-containing Bioactive Glasses for Use in Air Abrasion.

OBJECTIVES: To investigate the degradation, fluorapatite formation, biological safety and cutting efficiency on dentine of the mixed fluoride- and chloride-containing bioactive glasses (BGs). METHODS: Two series of mixed fluoride- and chloride-containing glasses (GPFCl and GPF2.3Cl series) were synthesized using a melt-quench method. Glass transition temperature (Tg) and the bioactivity in term of glass degradation and fluorapatite formation were evaluated in Tris buffer solution. The cutting efficiency of the powdered BGs (GPF2.3Cl series) on dentine via air abrasion was investigated using white light profilometry and scanning electron microscope. The cytotoxicity of GPF2.3Cl series on human periodontal ligament stem cells (hPLSCs) and oral fibroblasts (OFB) were examined by MTT. RESULTS: These BGs are highly degradable and able to form fluorapatite within 3h of immersion. The formation of CaF2 was also found in the high fluoride-containing BGs. The faster glass degradation was evidenced in the BGs with higher chloride. A significant reduction of Tg from 790°C to 463°C was seen with increasing in calcium halide content. Air abrasion on dentine using the low and intermediate chloride-containing glasses demonstrates clear depressions, while no depression was found using the high chloride-containing glass. Moreover, the studied BGs showed no cytotoxicity to hPLSCs and OFB. CONCLUSIONS: The glasses with mixed fluoride and chloride integrate the benefits from the presence of both, showing rapid glass degradation, fast fluorapatite formation, excellent biocompatibility and controllable hardness to provide a selective cutting efficiency on dentine. CLINICAL SIGNIFICANCE: The developed BGs air abrasive with tunable hardness by varying chloride content can selectively cut different dental tissues. In clinic, a relatively hard BG is of great interest for caries preparation, while a soft glass is attractive for tooth cleaning.

Halide-containing bioactive glasses enhance osteogenesis in vitro and in vivo.

The application of bone substitutes to reconstruct bone defects is a strategy for repairing alveolar bone loss caused by periodontal disease. Bioactive glasses (BGs) are attractive synthetic bone substitutes owing to their abilities to degrade, form bone-like mineral and stimulate bone regeneration. Our previous studies showed that the incorporation of fluoride into alkali-free bioactive silicate glass promoted osteogenesis to some extent in vitro, while the incorporation of chloride facilitated glass degradation and accelerated the formation of hydroxyapatite. However, whether there is a synergistic effect of incorporating fluoride and chloride on further enhancement of osteogenesis and angiogenesis in vitro and in vivo was not known. Therefore, we synthesized three halide-containing BGs with fluoride only, or chloride only, or mixed fluoride and chloride, investigated their physicochemical properties and osteogenic and angiogenic effects both in vitro and in vivo. The results showed that the addition of both fluoride and chloride in a bioactive silicate glass could combine the structural roles of both, leading to a faster apatite formation than the glass with the presence of fluoride only and a more stable fluorapatite formation than the glass with the presence of chloride only, which formed hydroxyapatite upon immersion. The studied BGs were cytocompatible, as suggested by the cytotoxicity evaluation of hPDLSCs cultivated in the extracted BGs-conditioned culture media. More importantly, these BGs stimulated osteogenic differentiation of hPDLSCs without adding growth factors as indicated by the fact that BGs-conditioned media up-regulated the expression of BMP-2, OPN and VEGF of hPDLSCs and promoted the formation of bone nodules and collagen in vitro. By comparison, the incorporation of fluoride facilitated the expression of osteogenic-related biomarkers and bone nodule formation preferentially, while the incorporation of chloride induced the expression of angiogenic-related biomarkers and collagen formation. The in vivo investigation results demonstrated that the developed halide-containing BGs accelerated the process of bone regeneration, while the glass with mixed fluoride and chloride showed the most significant promotion effect among the three BGs. Therefore, our findings revealed a synergistic effect of incorporating fluoride and chloride into a BG on osteogenesis and angiogenesis in vitro and in vivo and highlighted the potential of fluoride and chloride containing bioactive glasses being bone substitutes for clinical use.

Determination of chemical species of fluoride during uptake mechanism of glass-ionomer cements with NMR spectroscopy.

OBJECTIVE: The aim of the present study was to determine the chemical species formed inside glass-ionomer cements after fluoride uptake and to investigate the depth of penetration of fluoride ions within the cement matrix. METHODS: An experimental fluoride-free glass with composition 2SiO2-AlO3-CaO was produced. The glass powder was mixed with aqueous poly(acrylic acid) (PAA), and allowed to set. The resulting specimens were stored in 20ml KF solution with 1000ppm fluorine for 24h and then placed into the same amount of water as for 24h. A fluoride selective electrode was used to give the F concentration of the respective solutions. 19F MAS-NMR spectra were recorded on powdered cement specimens using a Bruker AVANCE-NEO 600 spectrometer. In addition, SEM observation and EDX chemical analysis were conducted on the cross-section of a carefully fractured specimen. RESULTS: Fluoride was shown to be mainly present in the surface layers of the specimen after placement in the KF solution, and only a small fraction was re-released into water. 19F NMR spectroscopy showed that AlF complexes were formed within the cement. SIGNIFICANCE: The fluoride taken up by a free-fluoride glass ionomer cement mostly occupies surface layers and is retained because it bonds to aluminum within the matrix. This finding explains why the majority of fluoride taken up by conventional glass ionomer cements is retained.

A comparative evaluation of ion release characteristics of three different dental varnishes containing fluoride either with CPP-ACP or bioactive glass.

OBJECTIVE: To compare ion release characteristics of three different dental varnishes either containing CPP-ACP and fluoride (CPP-ACPF, MI Varnish GC, Japan), bioactive glass and fluoride (BGAF, Dentsply Sirona USA) or fluoride alone (NUPRO White, Dentsply Sirona USA) using fluoride-Ion Selective Electrode (F-ISE), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), 19F and 31P Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). METHODS: A thin layer (0.0674±0.0005g) of each varnish (20×25mm in area) was spread on a roughened glass slide (n=7). They were separately immersed in 10ml Tris buffer (0.06M, pH=7.30), and changed after 1, 2, 4, 6, 24 and 48h. Fluoride-ion concentration at each time using the F-ISE, whilst calcium and phosphate release were investigated using ICP-OES. XRD, FTIR. MAS-NMR analyses were also performed before and after immersion. RESULTS: The cumulative F-ion release was significantly higher in CPP-ACPF (1.113mmol/g)>BGAF(0.638)>F(0.112) (p<0.001). The cumulative calcium and phosphorus were higher in the CPP-ACPF (0.137mmol/g, 0.119) than BGAF (0.067, 0.015) (p<0.001) respectively. The XRD and 19F MAS-NMR confirmed the presence of NaF peaks in all cases before immersion. There were less prominent signal and appearance of fluorapatite crystals after immersion. 19F MAS-NMR revealed CaF2 formation after immersion in both CPP-ACPF and BGAF. 31P MAS-NMR showed phosphate signals in both CPP-ACPF and BGAF before immersion. FTIR failed to show any signs of apatite formation. SIGNIFICANCE: Both CPP-ACP and bioactive glass enhanced ion release without compromising the bioavailability of fluoride. The CPP-ACPF varnish had the most promising ion release.

Molecular Dynamics Investigation of Halide-Containing Phospho-Silicate Bioactive Glasses.

Oxyhalide-containing silicate glasses have been receiving increasing attention in recent years due to their extensive medical and dental applications. This manuscript reports the first detailed structural investigation using MD simulations in the context of chloride- and mixed-fluoride/chloride-containing phospho-silicate bioactive glasses. It is shown that adding fluoride, chloride, and mixed fluoride and chloride has not altered the Q n silicate distribution and phosphorus speciation significantly in all of the glasses investigated. The Q2 silicon species is the predominant species with smaller and nearly equal proportions of Q1 and Q3 species, whereas phosphorus is largely present as orthophosphate Q0 units. No Si-F/Cl and P-F/Cl bonds have been observed at room temperature. Both F and Cl anions are present as F-Ca(n) and Cl-Ca(n). MD simulations also indicate opposite effects of fluoride and chloride on the crystallization ability of the glasses. The environment of Cl in chloride-containing glass series is quite different from the chlorapatite and CaCl2 crystals, and a significant structural reorganization is required to observe the appearance of the crystal nuclei. Instead, the environment of fluoride ions in the glasses is quite similar to that present in the FAP and CaF2 crystals and thus F-containing glasses manifest a high crystallization tendency. Moreover, in the mixed-fluoride/chloride-containing glasses, fluorine tends to surround phosphate, whereas chloride moves toward the silicate network. Finally, it was observed that a good correlation exists between the glass transition temperature and the overall strength of the glass network quantified by the Fnet factor.

Bioactivity and fluoride release of strontium and fluoride modified Biodentine.

Biodentine™ is a novel tricalcium silicate based material used both as a coronal dentine replacement and in pulp therapy. Its multiple use in sealing perforations, pulp capping and as a temporary restoration arises from its ability to promote dentine formation and to confer an excellent marginal seal. However, there is still room for improvement of this cement as it lacks the anticariogenic effect typically conferred by fluoride ion release as seen in glass ionomer cement based dental materials. Therefore, this study was conducted to investigate the impact of bioactive glass addition to Biodentine™. OBJECTIVE: was to compare the apatite formation capacity, specificity of the apatite type formed and fluoride ion release by Biodentine™ cements that have been modified by three different compositions of bioactive glasses. METHODS: High fluoride, high strontium and high fluoride plus strontium containing bioactive glasses were synthesized, incorporated into Biodentine™ powder and four types of cements prepared. These cements were immersed in phosphate buffered saline solution and incubated for a period of 3 and 24h, 3, 7 and 14 days. Fourier transform infra-red spectroscopy, X-ray diffraction, magic angle spinning nuclear magnetic resonance and fluoride ion release studies were performed. RESULTS: Bioactive glass addition to Biodentine™ led to pronounced formation of apatite. Where the bioactive glass contained fluoride, fluorapatite and fluoride ion release were demonstrated. SIGNIFICANCE: Eliciting fluorapatite formation and fluoride ion release from Biodentine™ is an important development as fluoride is known to have antibacterial and anticariogenic effects.

Predicting refractive index of fluoride containing glasses for aesthetic dental restorations.

OBJECTIVE: Dental restoration aesthetics, particularly the translucency of modern dental restorative filling materials depends on the refractive index (RI) match between the different components in the material. In the case of dental composites (DC), the RI of the polymer must match the RI of the filler otherwise the material is optically opaque and has limited depth of cure. In the case of glass ionomer cements (GICs), the RI of the ion-leachable glass must match the RI of the polysalts to engineer a smart material with a tooth-like appearance. The RI of oxide glasses can be calculated by means of Appen factors. However, no Appen factors are available for the fluoride components in dental glasses. Therefore, the objective of this study is to empirically derive composition-specific Appen factors for the metal fluorides in complex multicomponent glasses for use in dentistry. METHODS: Two series of bioactive glasses and two series of ionomer-type glasses were produced for this study. Refractive indices of all glasses were then measured by the Becke Line technique. Thereafter, composition-specific factors for the metal fluorides were derived. RESULTS: It was found that increasing metal fluoride content reduces the RI of multicomponent dental glasses linearly. A series-specific Appen factors for the metal fluorides were successfully derived and allow RI calculation to within 0.005. SIGNIFICANCE: This paper proposes a modified Appen Model with composition-specific Appen factors for the metal fluorides for the development of dental restoratives with enhanced aesthetics and improved depth of cure of dental composites.

Bioactive Glasses: Sprouting Angiogenesis in Tissue Engineering.

The biggest strategic challenge for tissue engineering is the development of efficient vascularized networks in engineered tissues and organs. Bioactive glasses (BGs) are potent biomaterials for inducing angiogenesis in hard and soft tissue engineering applications. Because tissue-healing processes strongly depend on angiogenesis, recent interest in BGs has increased dramatically. BGs with improved angiogenetic properties can be developed by adding a range of metallic ions (e.g., Cu2+, Co2+) into their structure, but further development of BGs with improved angiogenic activity is required, and many crucial questions remain to be answered. We introduce here the salient features, the hurdles that must be overcome, and the hopes and constraints for the development of this approach.

Dentine Tubule Occlusion by Novel Bioactive Glass-Based Toothpastes.

There are numerous over-the-counter (OTC) and professionally applied (in-office) products and techniques currently available for the treatment of dentine hypersensitivity (DH), but more recently, the use of bioactive glasses in toothpaste formulations have been advocated as a possible solution to managing DH. Aim. The aim of the present study, therefore, was to compare several bioactive glass formulations to investigate their effectiveness in an established in vitro model. Materials and Methods. A 45S5 glass was synthesized in the laboratory together with several other glass formulations: (1) a mixed glass (fluoride and chloride), (2) BioMinF, (3) a chloride glass, and (4) an amorphous chloride glass. The glass powders were formulated into five different toothpaste formulations. Dentine discs were sectioned from extracted human teeth and prepared for the investigation by removing the cutting debris (smear layer) following sectioning using a 6% citric acid solution for 2 minutes. Each disc was halved to provide test and control halves for comparison following the brushing of the five toothpaste formulations onto the test halves for each toothpaste group. Following the toothpaste application, the test discs were immersed in either artificial saliva or exposed to an acid challenge. Results. The dentine samples were analyzed using scanning electron microscopy (SEM), and observation of the SEM images indicated that there was good surface coverage following artificial saliva immersion. Furthermore, although the acid challenge removed the hydroxyapatite layer on the dentine surface for most of the samples, except for the amorphous chloride glass, there was evidence of tubular occlusion in the dentine tubules. Conclusions. The conclusions from the study would suggest that the inclusion of bioactive glass into a toothpaste formulation may be an effective approach to treat DH.

Bioactive glasses entering the mainstream.

Over the past decade, the extended research on bioactive glasses (BGs) has drastically grown because of their bioactive nature and unique ability to deliver therapeutics in tissue engineering, regenerative medicine and even cancer research. These strategies mostly rely on the inherent potential of BGs regarding bonding to the living tissues and accelerating the healing process. All the possibilities are strongly associated with releasing various therapeutic ions from the BG structures into the biological environment. Additionally, some types of glasses [i.e., mesoporous bioactive glasses (MBGs)] can serve as suitable platforms for the delivery of various small molecules and pharmaceutical agents. This class of biomaterials is recognised as a highly versatile delivery system, playing a crucial part in the future of medicine.

In-vitro apatite formation capacity of a bioactive glass - containing toothpaste.

OBJECTIVES: The in-vitro dissolution of bioactive glass-based toothpastes and their capacity to form apatite-like phases in buffer solutions have been investigated. MATERIALS AND METHODS: The commercial toothpaste samples were tested on immersion in artificial saliva, Earle's salt solution and Tris buffer for duration from 10min to four days. The powder samples collected at the end of the immersion were studied using solid-state 31P and 19F nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction and Fourier transform infrared (FTIR) spectroscopy. The fluoride concentration in the solution remained after the immersion was measured. RESULTS: In artificial saliva and in presence of sodium monofluorophosphate (MFP), the bioactive glass and bioactive glass-based toothpastes formed fluoridated apatite-like phases in under 10min. A small amount of apatite-like phase was detected by 31P NMR in the toothpaste with MFP but no bioactive glass. The toothpaste with bioactive glass but no fluoride formed an apatite-like phase as rapidly as the paste containing bioactive glass and fluoride. By contrast, apatite-like phase formation was much slower in Earle's salt solution than artificial saliva and slower than Tris buffer. CONCLUSIONS: The results of this lab-based study showed that the toothpaste with MFP and bioactive glass formed a fluoridated apatite in artificial saliva and in Tris buffer, as did the mixture of bioactive glass and MFP. CLINICAL SIGNIFICANCE: The presence of fluoride in bioactive glass-containing toothpastes can potentially lead to the formation of a fluoridated apatite, which may result in improved clinical effectiveness and durability. However, this should be further tested intra-orally.

Zinc bioglasses regulate mineralization in human dental pulp stem cells.

OBJECTIVE: A promising strategy in regenerative endodontics is the combination of human dental pulp stem cells (hDPSCs) with an appropriate biomaterial substrate. The effects of zinc and zinc containing bioactive glasses (ZnBGs) on hDPSCs have been characterized in this study. METHODS: ZnBGs were designed and produced. Then the odontogenic differentiation and mineralization potential of hDPSCs upon ZnBGs treatment were investigated. RESULTS: Free Zn ions (0-5ppm) enhanced proliferation and alkaline phosphatase (ALP) activity of hDPSCs. Further, ZnBGs conditioned medium (ZnBG-CM) increased the production and secretion of odontogenic markers: dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP-1). In addition, we identified that mRNA expression of the osteogenic markers RUNX2, OCN, BSP, BMP-2, MEPE and ON was increased following treatment with ZnBG-CM. Long term treatment with ZnBG-CM increases the formation rate of mineralized nodules (similar to hydroxyapatite, Ca:P=1.6), as confirmed by scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX). Lastly, the administration of ZnBG-CM induces VEGF expression. SIGNIFICANCE: These findings implicate that ZnBG would be beneficial in regenerative endodontics and could influence the way present Zn containing clinical products are used.

The effect of bioactive glasses on enamel remineralization: A systematic review.

INTRODUCTION/OBJECTIVES: To evaluate the effectiveness of bioactive glasses in promoting enamel remineralization. DATA: An electronic search with a complementary gray literature search for in vivo and in vitro research. No language restrictions were applied. SOURCES: MEDLINE and EMBASE via OVID, the Cochrane Oral Health Group's Trials Register, CENTRAL and LILACS STUDY SELECTION: One hundred and sixteen studies were identified, of which, eleven met the inclusion criteria and formed the basis of this systematic review. Methodological quality was assessed independently by two reviewers. Factors investigated in the selected articles included the objective and subjective measures of enamel remineralisation; harms, including evidence of damage to the enamel surface; patient satisfaction; and in vitro evidence of enamel remineralisation, using recognized laboratory techniques. RESULTS: A total of 11 laboratory-based studies were included in this review. The methodological quality was deemed to be high in four, and medium in the remaining studies. Based on the in vitro studies, enamel remineralization improved with bioactive glasses, irrespective of the method of application. Ex vivo signs of remineralization such as increase in enamel hardness, the formation of an enamel-protective layer and reduced intensity of light backscattering were less evident with alternatives including fluoride, and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). CONCLUSIONS: Based on in vitro findings only, bioactive glasses may be capable of enhancing enamel remineralization in various formulations, compared with other topical remineralizing materials including fluoride, and CPP-ACP. However, clinical research to confirm their effectiveness is now overdue. CLINICAL SIGNIFICANCE: Bioactive glasses have potential utility in promoting enamel remineralization; however, clinical research exploring their clinical effectiveness is required.