Natural monoterpenes-laden electrospun fibrous scaffolds for endodontic infection eradication.

This investigation aimed to synthesize poly(D,L-lactide) (PLA)-based fibrous scaffolds containing natural essential oils (i.e., linalool and citral) and determine their antimicrobial properties and cytocompatibility as a clinically viable cell-friendly disinfection strategy for regenerative endodontics. PLA-based fibrous scaffolds were fabricated via electrospinning with different concentrations of linalool and citral. The micromorphology and average diameter of the fibers was investigated through scanning electron microscopy (SEM). The chemical composition of the scaffolds was inferred by Fourier-transform infrared spectroscopy (FTIR). Antimicrobial efficacy against Enterococcus faecalis and Actinomyces naeslundii was also evaluated by agar diffusion and colony-forming units (CFU) assays. The scaffolds' cytocompatibility was determined using dental pulp stem cells (DPSCs). Statistical analyses were performed and the significance level was set at α = 5%. Linalool and citral's incorporation in the PLA fibrous scaffolds was confirmed in the FTIR spectra. SEM images indicate no morphological changes upon inclusion of the essential oils, except the reduced diameter of 40% linalool-laden fibers (p < 0.05). Importantly, significant antimicrobial properties were reported for citral-containing scaffolds for CFU/mL counts (p < 0.05), while only 20% and 40% linalool-laden scaffolds reduced CFU/mL (p < 0.05). Meanwhile, the inhibition halos were verified in a concentration-dependent manner for all monoterpenes-laden scaffolds. Citral- and linalool-laden PLA-based fibrous scaffolds showed acceptable cytocompatibility. The incorporation of natural monoterpenes did not alter the scaffolds' fibrous morphology, promoted antimicrobial action against endodontic pathogens, and preserved DPSCs viability. Linalool- and citral-laden electrospun scaffolds hold promise as naturally derived antimicrobial therapeutics for applications in regenerative endodontics.

Glass-ionomer cement modifies the gene expression of Streptococcus mutans providing a lower virulent biofilm.

PURPOSE: To evaluate the effect of glass-ionomer cement (GIC) on gene expression (gtfC, gtfD, covR, and vicR) of Streptococcus mutans (S. mutans) biofilms at 2, 4 and 24 hours. METHODS: Six groups were tested according to the materials and time observation, as follows: ceramic (IPS Empress Esthetic), as the control group, and GIC (Ketac Molar Easymix); and time points of S. mutans biofilm formation (2, 4, and 24 hours). Round-shaped samples (10 x 2 mm) of each material were prepared according to the manufacturers' specifications. GIC discs were handled in a laminar flow hood under aseptic conditions and stored at 100% relative humidity at 37°C for 24 hours to complete setting reaction. The samples were placed in a 24-well plate and immersed in 1.5 ml BHI + 1% sucrose with an inoculum of S. mutans UA159 to allow biofilm growth during 2, 4, and 24 hours. Next, the samples were removed, vortexed and centrifuged to collect cell pellets (n=5) for each material and time point. Pellets were stored at -80°C. Then, RNA was purified using the RNeasy Mini Kit protocol. The RNA was converted in cDNA using iScript cDNA Synthesis according to the manufacturer's recommendations. Analysis of gtfC, gtfD, vicR, and covR expressions was performed using Step One Real-Time qPCR device with specific primers for each gene and the analysis normalized by 16S reference gene expression. Data from gtfC, gtfD, and vicR were analyzed by t-test to compare between groups while Mann-Whitney was used to analyze covR expression (α= 0.05). RESULTS: No significant differences at 2 and 4 hours between materials for all analyzed genes were noted. However, in the 24-hour period, a significant decrease in gtfC and vicR expressions were observed, while covR expression increased when GIC was compared to ceramic. CLINICAL SIGNIFICANCE: The use of glass-ionomer cement decreased the virulence of S. mutans biofilms, which may imply a reduced bacterial cariogenic potential.

Loss-of-Function Mutations in the WNT Co-receptor LRP6 Cause Autosomal-Dominant Oligodontia.

Tooth agenesis is one of the most common developmental anomalies in man. Oligodontia, a severe form of tooth agenesis, occurs both as an isolated anomaly and as a syndromal feature. We performed exome sequencing on 20 unrelated individuals with apparent non-syndromic oligodontia and failed to detect mutations in genes previously associated with oligodontia. In three of the probands, we detected heterozygous variants in LRP6, and sequencing of additional oligodontia-affected individuals yielded one additional mutation in LRP6. Three mutations (c.1144_1145dupAG [p.Ala383Glyfs(∗)8], c.1779dupT [p.Glu594(∗)], and c.2224_2225dupTT [p.Leu742Phefs(∗)7]) are predicted to truncate the protein, whereas the fourth (c.56C>T [p.Ala19Val]) is a missense variant of a conserved residue located at the cleavage site of the protein's signal peptide. All four affected individuals harboring a LRP6 mutation had a family history of tooth agenesis. LRP6 encodes a transmembrane cell-surface protein that functions as a co-receptor with members from the Frizzled protein family in the canonical Wnt/ß-catenin signaling cascade. In this same pathway, WNT10A was recently identified as a major contributor in the etiology of non-syndromic oligodontia. We show that the LRP6 missense variant (c.56C>T) results in altered glycosylation and improper subcellular localization of the protein, resulting in abrogated activation of the Wnt pathway. Our results identify LRP6 variants as contributing to the etiology of non-syndromic autosomal-dominant oligodontia and suggest that this gene is a candidate for screening in DNA diagnostics.

Recent advances in additive manufacturing of patient-specific devices for dental and maxillofacial rehabilitation.

OBJECTIVES: Customization and the production of patient-specific devices, tailoring the unique anatomy of each patient's jaw and facial structures, are the new frontiers in dentistry and maxillofacial surgery. As a technological advancement, additive manufacturing has been applied to produce customized objects based on 3D computerized models. Therefore, this paper presents advances in additive manufacturing strategies for patient-specific devices in diverse dental specialties. METHODS: This paper overviews current 3D printing techniques to fabricate dental and maxillofacial devices. Then, the most recent literature (2018-2023) available in scientific databases reporting advances in 3D-printed patient-specific devices for dental and maxillofacial applications is critically discussed, focusing on the major outcomes, material-related details, and potential clinical advantages. RESULTS: The recent application of 3D-printed customized devices in oral prosthodontics, implantology and maxillofacial surgery, periodontics, orthodontics, and endodontics are presented. Moreover, the potential application of 4D printing as an advanced manufacturing technology and the challenges and future perspectives for additive manufacturing in the dental and maxillofacial area are reported. SIGNIFICANCE: Additive manufacturing techniques have been designed to benefit several areas of dentistry, and the technologies, materials, and devices continue to be optimized. Image-based and accurately printed patient-specific devices to replace, repair, and regenerate dental and maxillofacial structures hold significant potential to maximize the standard of care in dentistry.

Unveiling the potential of melt electrowriting in regenerative dental medicine.

For nearly three decades, tissue engineering strategies have been leveraged to devise effective therapeutics for dental, oral, and craniofacial (DOC) regenerative medicine and treat permanent deformities caused by many debilitating health conditions. In this regard, additive manufacturing (AM) allows the fabrication of personalized scaffolds that have the potential to recapitulate native tissue morphology and biomechanics through the utilization of several 3D printing techniques. Among these, melt electrowriting (MEW) is a versatile direct electrowriting process that permits the development of well-organized fibrous constructs with fiber resolutions ranging from micron to nanoscale. Indeed, MEW offers great prospects for the fabrication of scaffolds mimicking tissue specificity, healthy and pathophysiological microenvironments, personalized multi-scale transitions, and functional interfaces for tissue regeneration in medicine and dentistry. Excitingly, recent work has demonstrated the potential of converging MEW with other AM technologies and/or cell-laden scaffold fabrication (bioprinting) as a favorable route to overcome some of the limitations of MEW for DOC tissue regeneration. In particular, such convergency fabrication strategy has opened great promise in terms of supporting multi-tissue compartmentalization and predetermined cell commitment. In this review, we offer a critical appraisal on the latest advances in MEW and its convergence with other biofabrication technologies for DOC tissue regeneration. We first present the engineering principles of MEW and the most relevant design aspects for transition from flat to more anatomically relevant 3D structures while printing highly-ordered constructs. Secondly, we provide a thorough assessment of contemporary achievements using MEW scaffolds to study and guide soft and hard tissue regeneration, and draw a parallel on how to extrapolate proven concepts for applications in DOC tissue regeneration. Finally, we offer a combined engineering/clinical perspective on the fabrication of hierarchically organized MEW scaffold architectures and the future translational potential of site-specific, single-step scaffold fabrication to address tissue and tissue interfaces in dental, oral, and craniofacial regenerative medicine. STATEMENT OF SIGNIFICANCE: Melt electrowriting (MEW) techniques can further replicate the complexity of native tissues and could be the foundation for novel personalized (defect-specific) and tissue-specific clinical approaches in regenerative dental medicine. This work presents a unique perspective on how MEW has been translated towards the application of highly-ordered personalized multi-scale and functional interfaces for tissue regeneration, targeting the transition from flat to anatomically-relevant three-dimensional structures. Furthermore, we address the value of convergence of biofabrication technologies to overcome the traditional manufacturing limitations provided by multi-tissue complexity. Taken together, this work offers abundant engineering and clinical perspectives on the fabrication of hierarchically MEW architectures aiming towards site-specific implants to address complex tissue damage in regenerative dental medicine.

Effect of surfactants on the thermoresponse of PNIPAM investigated in the brush geometry.

HYPOTHESIS: Anionic surfactants have been reported to interact with poly(N-isopropyl acrylamide) (PNIPAM), suppressing its thermoresponse. Scattering and NMR studies of the anionic sodium dodecylsulfate (SDS) system propose that the PNIPAM-surfactant interaction is purely hydrophobic. However, prior phenomenological investigations of a range of surfactant identities (anionic, cationic, nonionic) show that only anionic surfactants affect the thermoresponse and conformation of PNIPAM, implying that the hydrophilic head-group also contributes. Crucially, the phenomenological experiments do not measure the affinity of the tested surfactants to the polymer, only their effect on its behaviour. EXPERIMENTS: We study the adsorption of six surfactants within a planar PNIPAM brush system, elucidating the polymer conformation, thermoresponse, and surfactant adsorption kinetics using ellipsometry, neutron reflectometry (NR), optical reflectometry and the quartz crystal microbalance technique. NR is used to measure the distribution of surfactants within the brush. FINDINGS: We find that only anionic surfactants modify the structure and thermoresponse of PNIPAM, with the greater affinity of anionic surfactants for PNIPAM (relative to cationic and nonionic surfactants) being the primary reason for this behaviour. These results show that the surfactant head-group has a more critical role in mediating PNIPAM-surfactant interaction than previously reported. Taking inspiration from prior molecular dynamics work on the PEO-surfactant system, we propose an interaction mechanism for PNIPAM and SDS that reconciles evidence for hydrophobic interaction with the observed head-group-dependent affinity.

From Hofmeister to hydrotrope: Effect of anion hydrocarbon chain length on a polymer brush.

HYPOTHESIS: Specific ion effects govern myriad biological phenomena, including protein-ligand interactions and enzyme activity. Despite recent advances, detailed understanding of the role of ion hydrophobicity in specific ion effects, and the intersection with hydrotropic effects, remains elusive. Short chain fatty acid sodium salts are simple amphiphiles which play an integral role in our gastrointestinal health. We hypothesise that increasing a fatty acid's hydrophobicity will manifest stronger salting-out behaviour. EXPERIMENTS: Here we study the effect of these amphiphiles on an exemplar thermoresponsive polymer brush system, conserving the carboxylate anion identity while varying anion hydrophobicity via the carbon chain length. Ellipsometry and quartz crystal microbalance with dissipation monitoring were used to characterise the thermoresponse and viscoelasticity of the brush, respectively, whilst neutron reflectometry was used to reveal the internal structure of the brush. Diffusion-ordered nuclear magnetic resonance spectroscopy and computational investigations provide insight into polymer-ion interactions. FINDINGS: Surface sensitive techniques unveiled a non-monotonic trend in salting-out ability with increasing anion hydrophobicity, revealing the bundle-like morphology of the ion-collapsed system. An intersection between ion-specific and hydrotropic effects was observed both experimentally and computationally; trending from good anti-hydrotrope towards hydrotropic behaviour with increasing anion hydrophobicity, accompanying a change in hydrophobic hydration.

Transcriptional Regulation of Jaw Osteoblasts: Development to Pathology.

Craniofacial and jaw bones have unique physiological specificities when compared to axial and appendicular bones. However, the molecular profile of the jaw osteoblast (OB) remains incomplete. The present study aimed to decipher the bone site-specific profiles of transcription factors (TFs) expressed in OBs in vivo. Using RNA sequencing analysis, we mapped the transcriptome of confirmed OBs from 2 different skeletal sites: mandible (Md) and tibia (Tb). The OB transcriptome contains 709 TF genes: 608 are similarly expressed in Md-OB and Tb-OB, referred to as "OB-core"; 54 TF genes are upregulated in Md-OB, referred to as "Md-set"; and 18 TF genes are upregulated in Tb-OB, referred to as "Tb-set." Notably, the expression of 29 additional TF genes depends on their RNA transcript variants. TF genes with no previously known role in OBs and bone were identified. Bioinformatics analysis combined with review of genetic disease databases and a comprehensive literature search showed a significant contribution of anatomical origin to the OB signatures. Md-set and Tb-set are enriched with site-specific TF genes associated with development and morphogenesis (neural crest vs. mesoderm), and this developmental imprint persists during growth and homeostasis. Jaw and tibia site-specific OB signatures are associated with craniofacial and appendicular skeletal disorders as well as neurocristopathies, dental disorders, and digit malformations. The present study demonstrates the feasibility of a new method to isolate pure OB populations and map their gene expression signature in the context of OB physiological environment, avoiding in vitro culture and its associated biases. Our results provide insights into the site-specific developmental pathways governing OBs and identify new major OB regulators of bone physiology. We also established the importance of the OB transcriptome as a prognostic tool for human rare bone diseases to explore the hidden pathophysiology of craniofacial malformations, among the most prevalent congenital defects in humans.

Self-assembling peptide-laden electrospun scaffolds for guided mineralized tissue regeneration.

OBJECTIVES: Electrospun scaffolds are a versatile biomaterial platform to mimic fibrillar structure of native tissues extracellular matrix, and facilitate the incorporation of biomolecules for regenerative therapies. Self-assembling peptide P11-4 has emerged as a promising strategy to induce mineralization; however, P11-4 application has been mostly addressed for early caries lesions repair on dental enamel. Here, to investigate P11-4's efficacy on bone regeneration, polymeric electrospun scaffolds were developed, and then distinct concentrations of P11-4 were physically adsorbed on the scaffolds. METHODS: P11-4-laden and pristine (P11-4-free) electrospun scaffolds were immersed in simulated body fluid and mineral precipitation identified by SEM. Functional groups and crystalline phases were analyzed by FTIR and XRD, respectively. Cytocompatibility, mineralization, and gene expression assays were conducted using stem cells from human exfoliated deciduous teeth. To investigate P11-4-laden scaffolds potential to induce in vivo mineralization, an established rat calvaria critical-size defect model was used. RESULTS: We successfully synthesized nanofibrous (∼ 500 nm fiber diameter) scaffolds and observed that functionalization with P11-4 did not affect the fibers' diameter. SEM images indicated mineral precipitation, while FTIR and XRD confirmed apatite-like formation and crystallization for P11-4-laden scaffolds. In addition, P11-4-laden scaffolds were cytocompatible, highly stimulated cell-mediated mineral deposition, and upregulated the expression of mineralization-related genes compared to pristine scaffolds. P11-4-laden scaffolds led to enhanced in vivo bone regeneration after 8 weeks compared to pristine PCL. SIGNIFICANCE: Electrospun scaffolds functionalized with P11-4 are a promising strategy for inducing mineralized tissues regeneration in the craniomaxillofacial complex.

Effect of a Self-Assembly Peptide on Surface Roughness and Hardness of Bleached Enamel.

After bleaching, enamel surfaces are damaged, contributing to erosion and tooth sensitivity. Although fluoride is used after bleaching to try and revert alterations, it is not capable of repairing tooth structure. This study compared the effect of a self-assembly peptide (P11-4), with and without fluoride, and sodium fluoride (NaF 2%) on the Knoop microhardness (KHN) and surface roughness (Ra (µm)) of bleached enamel with an in-office bleaching regimen. Enamel blocks of bovine teeth (5 × 5 × 2 mm) with standardized surface hardness were bleached with 35% carbamide peroxide, following the manufacturer's instructions. The teeth were randomly divided into the following groups (n = 7) according to post-bleaching treatment: no treatment (negative control) (C-); 2% NaF (NaF); Curodont™ Repair (Repair); and Curodont™ Protect (Protect). Specimens were stored in artificial saliva at 37 °C. To evaluate the effect of the post-bleaching treatments, KHN and Ra were measured before bleaching (baseline) and 24 h and 7 days after bleaching. Data were submitted to repeated measures ANOVA and Bonferroni tests (α = 0.05). There were significant interactions between the study factors (p = 0.001). After 7 days, Repair (572.50 ± 79.04) and Protect (583.00 ± 74.76) specimens showed increased surface KHN, with values higher than the NaF (465.50 ± 41.50) and C- (475.22 ± 58.95) baseline values. There was no significant difference in KHN at 24 h among groups (p = 0.587). At 24 h after bleaching, Repair was significantly different from all groups (p < 0.05). Repair showed the lowest Ra (µm) values (0.133 ± 0.035). After seven days, there was no significant difference in Ra values among groups when compared to the baseline. The use of P11-4-based materials after bleaching resulted in the fastest recovery to baseline enamel properties.

Coupling Lipid Nanoparticle Structure and Automated Single-Particle Composition Analysis to Design Phospholipase-Responsive Nanocarriers.

Lipid nanoparticles (LNPs) are versatile structures with tunable physicochemical properties that are ideally suited as a platform for vaccine delivery and RNA therapeutics. A key barrier to LNP rational design is the inability to relate composition and structure to intracellular processing and function. Here Single Particle Automated Raman Trapping Analysis (SPARTA) is combined with small-angle X-ray and neutron scattering (SAXS/SANS) techniques to link LNP composition with internal structure and morphology and to monitor dynamic LNP-phospholipase D (PLD) interactions. This analysis demonstrates that PLD, a key intracellular trafficking mediator, can access the entire LNP lipid membrane to generate stable, anionic LNPs. PLD activity on vesicles with matched amounts of enzyme substrate is an order of magnitude lower, indicating that the LNP lipid membrane structure can be used to control enzyme interactions. This represents an opportunity to design enzyme-responsive LNP solutions for stimuli-responsive delivery and diseases where PLD is dysregulated.

Effects of strontium-doped bioactive glass on the differentiation of cultured osteogenic cells.

There is accumulating evidence that strontium-containing biomaterials have positive effects on bone tissue repair. We investigated the in vitro effect of a new Sr-doped bioactive glass manufactured by the sol-gel method on osteoblast viability and differentiation. Osteoblasts isolated from foetal mouse calvaria were cultured in the presence of bioactive glass particles; particles were undoped (B75) or Sr-doped with 1 wt.% (B75-Sr1) and 5 wt.% (B75-Sr5). Morphological analysis was carried out by contrast-phase microscopy and scanning electron microscopy (SEM). Cell viability was evaluated by the MTS assay at 24 h, 48 h and 72 h. At 24 h, day 6 and day 12, osteoblast differentiation was evaluated by assaying alkaline phosphatase (ALP) activity, osteocalcin (OC) secretion and gene expression of various bone markers, using Real-Time-PCR. Alizarin Red staining and ALP histoenzymatic localisation were performed on day 12. Microscopic observations and MTS showed an absence of cytotoxicity in the three investigated bioactive glasses. B75-Sr5 particles in cell cultures, in comparison with those of B75 and B75-Sr1, resulted in a significant up-regulation of Runx2, Osterix, Dlx5, collagen I, ALP, bone sialoprotein (BSP) and OC mRNA levels on day 12, which was associated with an increase of ALP activity on day 6 and OC secretion on day 12. In conclusion, osteoblast differentiation of foetal mouse calvarial cells was enhanced in the presence of bioactive glass particles containing 5 wt.% strontium. Thus, B75-Sr5 may represent a promising bone-grafting material for bone regeneration procedures.

A Highly Ordered, Nanostructured Fluorinated CaP-Coated Melt Electrowritten Scaffold for Periodontal Tissue Regeneration.

Periodontitis is a chronic inflammatory, bacteria-triggered disorder affecting nearly half of American adults. Although some level of tissue regeneration is realized, its low success in complex cases demands superior strategies to amplify regenerative capacity. Herein, highly ordered scaffolds are engineered via Melt ElectroWriting (MEW), and the effects of strand spacing, as well as the presence of a nanostructured fluorinated calcium phosphate (F/CaP) coating on the adhesion/proliferation, and osteogenic differentiation of human-derived periodontal ligament stem cells, are investigated. Upon initial cell-scaffold interaction screening aimed at defining the most suitable design, MEW poly(ε-caprolactone) scaffolds with 500 µm strand spacing are chosen. Following an alkali treatment, scaffolds are immersed in a pre-established solution to allow for coating formation. The presence of a nanostructured F/CaP coating leads to a marked upregulation of osteogenic genes and attenuated bacterial growth. In vivo findings confirm that the F/CaP-coated scaffolds are biocompatible and lead to periodontal regeneration when implanted in a rat mandibular periodontal fenestration defect model. In aggregate, it is considered that this work can contribute to the development of personalized scaffolds capable of enabling tissue-specific differentiation of progenitor cells, and thus guide simultaneous and coordinated regeneration of soft and hard periodontal tissues, while providing antimicrobial protection.

Bioengineered titanium surfaces affect the gene-expression and phenotypic response of osteoprogenitor cells derived from mouse calvarial bones.

This study investigated the in vitro effects of bioactive titanium surfaces on osteoblast differentiation. Three titanium substrates were tested: a commercially pure titanium (Cp Ti), an alkali- and heat-treated titanium (AH Ti), and an apatite-formed titanium (Ap Ti) generated by soaking AH Ti in a simulated body fluid. Chemical evaluation of the surface reactivity was analysed at nanometre scale by X-ray photoelectron spectroscopy (XPS), and at micrometre scale by energy dispersive X-ray microanalysis (EDX). It showed that the estimated proportion of the surface covered by adsorbed serum proteins differed between the three substrates and confirmed the bioactivity of AH Ti, illustrated by surface calcium and phosphate deposition when immersed in biological fluids. Mouse calvaria osteoblasts were cultured on the substrates for 15 days with no sign of cytotoxicity. Enzyme immunoassay and Real-Time RT-PCR were used to follow osteoblast differentiation through the production of osteocalcin (OC) and expression of several bone markers. At day 15, a significant up-regulation of Runx2, Osx, Dlx5, ALP, BSP, OC and DMP1 mRNA levels associated with an increase of OC production were observed on AH Ti and Ap Ti when compared to Cp Ti. These results suggest that bioengineered titanium has a great potential for dental applications in enhancing osseointegration.

Enzyme-instructed molecular self-assembly confers nanofibers and a supramolecular hydrogel of taxol derivative.

By covalently connecting taxol with a motif that is prone to self-assemble, we successfully generate the precursor (5a), the hydrogelator (5b), and hydrogel of a taxol derivative without compromising the cytotoxic activity of the taxol. This approach promises a general method to create nanofibers of therapeutic molecules that have a dual role, as both the delivery vehicle and the drug itself.

Buoyancy-Driven Gradients for Biomaterial Fabrication and Tissue Engineering.

The controlled fabrication of gradient materials is becoming increasingly important as the next generation of tissue engineering seeks to produce inhomogeneous constructs with physiological complexity. Current strategies for fabricating gradient materials can require highly specialized materials or equipment and cannot be generally applied to the wide range of systems used for tissue engineering. Here, the fundamental physical principle of buoyancy is exploited as a generalized approach for generating materials bearing well-defined compositional, mechanical, or biochemical gradients. Gradient formation is demonstrated across a range of different materials (e.g., polymers and hydrogels) and cargos (e.g., liposomes, nanoparticles, extracellular vesicles, macromolecules, and small molecules). As well as providing versatility, this buoyancy-driven gradient approach also offers speed (<1 min) and simplicity (a single injection) using standard laboratory apparatus. Moreover, this technique is readily applied to a major target in complex tissue engineering: the osteochondral interface. A bone morphogenetic protein 2 gradient, presented across a gelatin methacryloyl hydrogel laden with human mesenchymal stem cells, is used to locally stimulate osteogenesis and mineralization in order to produce integrated osteochondral tissue constructs. The versatility and accessibility of this fabrication platform should ensure widespread applicability and provide opportunities to generate other gradient materials or interfacial tissues.

In vitro analysis of the penetration of methylene blue dye in human radicular dentin using different methods of impregnation.

The purpose of the present study was to verity whether different conditions of contact with a dye solution would result in different levels of the impregnation by the marker agent in human radicular dentin. The root canals of 60 upper human canines were immersed in methylene blue dye (0.5%, pH 7.0) for 24 h under six different conditions: passive immersion; pre-agitation for 10 min using an endodontic ultrasound; pre-agitation for 10 min using a cleaning ultrasound; 25-mmHg vacuum for 10 min followed by passive immersion; 30-mmHg and 650-mmHg vacuum for 24 h. The roots were longitudinally sectioned and dye impregnation was assessed by a trained and calibrated examiner, using the Q 550 IW image analyser (Leica Qwin, Cambridge, England). The measurements were analysed with anova and Tukey test. The results revealed no significant difference among the different methods for dye impregnation. In the cervical third, impregnation with 30 mmHg was significantly more effective than with endodontic ultrasound or 25 mmHg. At the apical third, no differences were observed between any of the dye impregnation methods. The comparison of different thirds revealed a statistically significant difference between the cervical and apical and the middle and apical thirds, but not between the cervical and middle thirds.

Glycosylated superparamagnetic nanoparticle gradients for osteochondral tissue engineering.

In developmental biology, gradients of bioactive signals direct the formation of structural transitions in tissue that are key to physiological function. Failure to reproduce these native features in an in vitro setting can severely limit the success of bioengineered tissue constructs. In this report, we introduce a facile and rapid platform that uses magnetic field alignment of glycosylated superparamagnetic iron oxide nanoparticles, pre-loaded with growth factors, to pattern biochemical gradients into a range of biomaterial systems. Gradients of bone morphogenetic protein 2 in agarose hydrogels were used to spatially direct the osteogenesis of human mesenchymal stem cells and generate robust osteochondral tissue constructs exhibiting a clear mineral transition from bone to cartilage. Interestingly, the smooth gradients in growth factor concentration gave rise to biologically-relevant, emergent structural features, including a tidemark transition demarcating mineralized and non-mineralized tissue and an osteochondral interface rich in hypertrophic chondrocytes. This platform technology offers great versatility and provides an exciting new opportunity for overcoming a range of interfacial tissue engineering challenges.

Opportunities in oral health policy for Timor-Leste.

Timor-Leste faces an urgent set of challenges in oral health. The impact of oral diseases in terms of reduced quality of life and cost of treatment is considerable. This paper reviews progress on policy recommendations since the National Oral Health Survey in 2002, the first such national survey. Few proposals have been implemented to date, owing to (i) lack of local support for the recommendations, particularly on promotion of oral health; (ii) lack of financial and budgetary provisions for oral health; (iii) lack of focus on services, human resources and dental personnel; (iv) poor focus, design and implementation of policy and planning in oral health; and (v) lack of transport to facilitate health-care workers' access to remote areas. Based on this assessment, the present paper presents a reconfigured set of policies and recommendations for oral health that take into consideration the reasons for low uptake of previous guidance. Key priorities are promotion of oral health, legislative interventions, education of the oral-health workforce, dental outreach programmes, targeted dental treatment, dental infrastructure programmes, and research and evaluation. Interventions include promotion of oral health for schoolchildren, salt fluoridation, fluoride toothpaste and banning sweet stalls and use of tobacco and betel nut in, or near, schools. Timor-Leste should strengthen the availability and quality of outreach programmes for oral health. Dental therapists and dental nurses who can supply preventive and atraumatic restorative dental care should continue to be trained, and the planned dentistry school should be established. Ongoing research and evaluation is needed to ensure that the approach being used in Timor-Leste is leading to improved outcomes in oral health.

Early nonsurgical correction of congenital auricular deformities.

Congenital auricular deformation is not an uncommon phenomenon, and it may cause substantial annoyance to the growing child. Many parents of affected children will seek surgical correction of the deformed auricles. The variety of techniques that have been described for the correction of this anomaly suggests that none has been considered satisfying. The consequent possible surgical complications should also be considered, when the surgical procedure can be replaced by an effective conservative treatment. The authors describe their experience using early splinting for congenital auricular deformities. Fifty-two newborn infants with lop, prominent, Stahl's, and constricted ears referred to us by the neonatal department staff were enrolled in this study. Putty Soft, a vinyl polysiloxane impression material, has been used for early molding of the auricles. Surgical tapes were used for the fixation of the mold and to fix the auricle to the scalp. The results were evaluated by one of the parents and by a layperson (medical student) 6 months after completion of the procedure. The above-described early splinting procedure was applied onto 92 auricles of 52 newborn infants aged 1 to 10 days, mostly around day 3. The mean treatment time was 6.8 weeks. All treated auricles were improved, 87 percent were rated as excellent improvement, and there were no complications related to the treatment. The authors conclude that early splinting of deformed auricles should be offered to parents of affected children, and the awareness of this procedure by neonatologists, pediatricians, and nursery staff should be increased.