Innovative Approaches to Regenerate Enamel and Dentin

The process of tooth mineralization and the role of molecular control of cellular behavior during embryonic tooth development have attracted much attention the last few years. The knowledge gained from the research in these fields has improved the general understanding about the formation of dental tissues and the entire tooth and set the basis for teeth regeneration. Tissue engineering using scaffold and cell aggregate methods has been considered to produce bioengineered dental tissues, while dental stem/progenitor cells, which can differentiate into dental cell lineages, have been also introduced into the field of tooth mineralization and regeneration. Some of the main strategies for making enamel, dentin, and complex tooth-like structures are presented in this paper. However, there are still significant barriers that obstruct such strategies to move into the regular clinic practice, and these should be overcome in order to have the regenerative dentistry as the important mean that can treat the consequences of tooth-related diseases

Orai1 expression pattern in tooth and craniofacial ectodermal tissues and potential functions during ameloblast differentiation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113781/1/dvdy24307.pd

Fabrication and investigation of modified materials suitable for dental fixed prosthetic restorations with possibilities of grouth of complex biological stuctures

The aim of this study was the fabrication and the investigation of modified bioceramics, with possibilities of growth of complex biological structures, suitable for dental fixed prosthetic restorations. Three groups of materials were studied for the achievement of the aim: a. the primary materials (three types of dental porcelains, bioactive glass in the system SiO2-CaO-Na2O-P2O5 and commercial hydroxyapatite), b. composite materials aimed to the reinforcement of the bioactive glass (bioactive glass-commercial hydroxyapatite, bioactive glass-alumina) and c. mixtures (dental porcelain-bioactive glass, dental porcelain-bioactive glass- commercial hydroxyapatite, dental porcelain-bioactive glass-alumina). All samples were characterized before and after the application of appropriate thermal treatments. The characterization of the materials was performed by Infrared Spectroscopy (FTIR), X-ray Diffractometry, Thermal Analysis (TG-DTA), Transmittance Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM-EDS). Moreover, the bioactive behavior of the materials was investigated through the immersion in the Simulated Body Fluid (SBF). For each soaking time the surface of the samples was characterized in order to be studied the ability of the formation of the biological hydroxyapatite (HCAp) layer on it. The mixture: dental porcelain IPS Classic 50% - commercial hydroxyapatite 35% - bioactive glass 15% (C-HAp) was found as the most convenient for the modification of dental ceramics, suitable for dental fixed prosthetic restorations. This mixture presents formation of the HCAp layer after 20 days of immersion in SBF, which is the fastest time of growth that is observed among the modified surfaces. This behavior is attributed both to the contents of the mixture and to the applied thermal treatment.Σκοπός της παρούσας εργασίας ήταν η παρασκευή και μελέτη τροποποιημένων βιοκεραμικών, με δυνατότητα δημιουργίας βιοενεργής επιφάνειας, κατάλληλων για ακίνητες προσθετικές αποκαταστάσεις. Για την επίτευξη του στόχου διερευνήθηκαν τρεις ομάδες υλικών: α. τα πρωτογενή υλικά (τρία είδη οδοντιατρικών πορσελανών, βιοενεργή ύαλος στο σύστημα SiO2-CaO-Na2O-P2O5 και χημικός υδροξυαπατίτης), β. σύνθετα υλικά για την ενίσχυση της βιοϋάλου (βιοενεργή ύαλος-χημικός υδροξυαπατίτης, βιοενεργή ύαλος-αλουμίνα) και γ. μικτά υλικά (οδοντιατρική πορσελάνη-βιοενεργή ύαλος, οδοντιατρική πορσελάνη-βιοενεργή ύαλος-χημικός υδροξυαπατίτης, οδοντιατρική πορσελάνη-βιοενεργή ύαλος-αλουμίνα). Σε κάθε περίπτωση πραγματοποιήθηκε χαρακτηρισμός των φυσικών ιδιοτήτων πριν και μετά την εφαρμογή κατάλληλων συνθηκών θερμικής επεξεργασίας. Οι τεχνικές χαρακτηρισμού που χρησιμοποιήθηκαν ήταν η φασματοσκοπία υπερύθρου (FTIR), η περιθλασιμετρία ακτίνων-Χ, η θερμική ανάλυση (TG-DTA), η ηλεκτρονική μικροσκοπία διέλευσης (ΤΕΜ), καθώς και η ηλεκτρονική μικροσκοπία σάρωσης (SEM-EDS). Στη συνέχεια σημειώθηκε έλεγχος της βιοενεργής συμπεριφοράς των υλικών με εμβάπτισή τους σε διάλυμα προσομοίωσης του πλάσματος του ανθρωπίνου αίματος (Simulated Body Fluid-SBF). Ακολούθησε χαρακτηρισμός των επιφανειών των δειγμάτων μετά την έξοδό τους από το διάλυμα για κάθε χρόνο παραμονής, προκειμένου να εξεταστεί η δυνατότητα σχηματισμού στρώματος βιολογικού υδροξυαπατίτη (HCAp) στην επιφάνειά τους. Ως καταλληλότερο υλικό τροποποίησης, των οδοντιατρικών κεραμικών που βρίσκουν εφαρμογή στις ακίνητες προσθετικές αποκαταστάσεις, βρέθηκε το μίγμα οδοντιατρικής πορσελάνης IPS Classic 50%, χημικού υδροξυαπατίτη 35% και βιοενεργής υάλου 15% (C-ΗΑp), το οποίο επιτρέπει τον σχηματισμό ανθρακικού υδροξυαπατίτη σε 20 ημέρες εμβάπτισης στο SBF, o οποίος αποτελεί τον βέλτιστο χρόνο ανάπτυξης στις τροποποιημένες επιφάνειες. Η συμπεριφορά αυτή είναι αποτέλεσμα τόσο των συστατικών του μίγματος που χρησιμοποιήθηκαν όσο και της εφαρμοζόμενης θερμικής επεξεργασίας

Physical Properties of an Ag-Doped Bioactive Flowable Composite Resin

The aim of this work was to study the physical and antibacterial properties of a flowable resin composite incorporating a sol-gel derived silver doped bioactive glass (Ag-BGCOMP). The depth of the cure was calculated by measuring the surface micro-hardness for the top and bottom surfaces. The volumetric polymerization shrinkage was measured by recording the linear shrinkage as change in length, while the biaxial flexural strength was studied measuring the load at failure. The antibacterial properties of the samples were tested against Streptococcus mutans (S. mutans) and Lactobacillus casei (L. casei). The measured values were slightly decreased for all tested physical properties compared to those of control group (flowable resin composite without Ag-BG), however enhanced bacteria inhibition was observed for Ag-BGCOMP. Ag-BGCOMP could find an application in low stress-bearing areas as well as in small cavity preparations to decrease secondary caries. This work provides a good foundation for future studies on evaluating the effects of Ag-BG addition into packable composites for applications in larger cavity preparations where enhanced mechanical properties are needed

High Boron Content Enhances Bioactive Glass Biodegradation

International audienceDerived Hench bioactive glass (BaG) containing boron (B) is explored in this work as it plays an important role in bone development and regeneration. B was also found to enhance BaG dissociation. However, it is only possible to incorporate a limited amount of B. To increase the amount of B in BaG, bioactive borosilicate glasses (BaG-B-x) were fabricated based on the use of the solution-gelation process (sol-gel). In this work, a high B content (20 wt.%) in BaG, respecting the conditions of bioactivity and biodegradability required by Hench, was achieved for the first time. The capability of BaG-B-x to form an apatite phase was assessed in vitro by immersion in simulated body fluid (SBF). Then, the chemical structure and the morphological changes in the fabricated BaG-B-x (x = 0, 5, 10 and 20) were studied. The formation of hydroxyapatite (HAp) layer was observed with X-ray diffraction (XRD) and infrared (IR) spectroscopy. The presence of HAp layer was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Enhanced bioactivity and chemical stability of BaG-B-x were evaluated with an ion exchange study based on Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and energy dispersive spectroscopy (EDS). Results indicate that by increasing the concentration of B in BaG-Bx, the crystallization rate and the quality of the newly formed HAp layer on BaG-B-x surfaces can be improved. The presence of B also leads to enhanced degradation of BaGs in SBF. Accordingly, BAG-B-x can be used for bone regeneration, especially in children, because of its faster degradation as compared to B-free glass

Highlights on Advancing Frontiers in Tissue Engineering

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Bactericidal and Bioactive Dental Composites

Aim: Antimicrobial and bioactive restorative materials are needed to develop a bacteria free environment and tight bond with the surrounding tissue, preventing the spread of secondary caries and thus extending the lifetime of dental restorations. The characteristic properties of new dental bioactive and antibacterial composites are presented in this work. The new composites have been microstructurally characterized and both long and short term properties have been studied.Methods: The Ag-doped sol-gel derived bioactive glass (Ag-BG) was incorporated into resin composite in concentrations 5, 10, and 15 wt.%, to fabricate new Ag-doped bioactive and antibacterial dental composites (Ag-BGCOMP). The microstructural properties and elemental analysis of the developed Ag-BGCOMP was observed. The total bond strength (TBS) was measured immediately and after long term of immersion in medium using microtensile testing. The capability of Ag-BGCOMPs to form apatite layer on their surface after immersion in Simulated Body Fluid (SBF) as well as the bacteria growth inhibition in a biofilm formed by Streptococcus mutans (S. mutans) were evaluated.Results: Homogeneous distribution of Ag-BG particles into the resin composite was observed microstructurally for all Ag-BGCOMPs. The TBS measurements showed non-statistically significant difference between control samples (Ag-BG 0 wt.%) and Ag-BGCOMP specimens. Moreover, the total bond strength between the surrounding tooth tissue and the material of restoration does not present any statistically significant change for all the cases even after 3 months of immersion in the medium. The bioactivity of the Ag-BGCOMPs was also shown by the formation of a calcium-phosphate layer on the surface of the specimens after immersion in SBF. Antibacterial activity was observed for all Ag-BGCOMPs, statistically significant differences were observed between control samples and Ag-BGCOMPs. Accordingly, the number of dead bacteria in the biofilm found to increase significantly with the increase of Ag-BG concentration in the Ag-BGCOMPs.Conclusions: New resin composites with antibacterial and remineralizing properties have been manufactured. Characterization of these materials provides a rationale for future clinical trials to evaluate clinical benefits and outcomes in comparison with currently used dental materials.Significance: The new developed composites could ultimately prevent restoration failure and could advance patients' wellbeing