Search

Nature uses extracellular matrix scaffolds to organize biominerals into hierarchical structures over various length scales. This has inspired the design of biomimetic mineralization scaffolds, with DNA nanostructures being among the most promising. DNA nanotechnology makes use of molecular recognition to controllably give 1D, 2D and 3D nanostructures. The control we have over these structures makes them attractive templates for the synthesis of mineralized tissues, such as bones and teeth. In this Review, we first summarize recent work on the crystallization processes and structural features of biominerals on the nanoscale. We then describe self-assembled DNA nanostructures and come to the intersection of these two themes: recent applications of DNA templates in nanoscale biomineralization, a crucial process to regenerate mineralized tissues., (© 2021. Springer Nature Limited.)

The oral and craniofacial region consists of various types of hard and soft tissues with the intricate organization. With the high prevalence of tissue defects in this specific region, it is highly desirable to enhance tissue regeneration through the development and use of engineered biomaterials. Collagen, the major component of tissue extracellular matrix, has come into the limelight in regenerative medicine. Although collagen has been widely used as an essential component in biomaterial engineering owing to its low immunogenicity, high biocompatibility, and convenient extraction procedures, there is a limited number of reviews on this specific clinic sector. The need for mechanical enhancement and functional engineering drives intensive efforts in collagen-based biomaterials concentrating on therapeutical outcomes and clinical translation in oral and craniofacial tissue regeneration. Herein, we highlighted the status quo of the design and applications of collagen-based biomaterials in oral and craniofacial tissue reconstruction. The discussion expanded on the inspiration from the leather tanning process on modifications of collagen-based biomaterials and the prospects of multi-tissue reconstruction in this particular dynamic microenvironment. The existing findings will lay a new foundation for the optimization of current collagen-based biomaterials for rebuilding oral and craniofacial tissues in the future. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Literature Pharmacy Sciences is the property of Turkiye Klinikleri and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Secondary caries is one of the leading causes of resin-based dental restoration failure. It is initiated at the interface of an existing restoration and the restored tooth surface. It is mainly caused by an imbalance between two processes of mineral loss (demineralization) and mineral gain (remineralization). A plethora of evidence has explored incorporating several bioactive compounds into resin-based materials to prevent bacterial biofilm attachment and the onset of the disease. In this review, the most recent advances in the design of remineralizing compounds and their functionalization to different resin-based materials' formulations were overviewed. Inorganic compounds, such as nano-sized amorphous calcium phosphate (NACP), calcium fluoride (CaF2), bioactive glass (BAG), hydroxyapatite (HA), fluorapatite (FA), and boron nitride (BN), displayed promising results concerning remineralization, and direct and indirect impact on biofilm growth. The effects of these compounds varied based on these compounds' structure, the incorporated amount or percentage, and the intended clinical application. The remineralizing effects were presented as direct effects, such as an increase in the mineral content of the dental tissue, or indirect effects, such as an increase in the pH around the material. In some of the reported investigations, inorganic remineralizing compounds were combined with other bioactive agents, such as quaternary ammonium compounds (QACs), to maximize the remineralization outcomes and the antibacterial action against the cariogenic biofilms. The reviewed literature was mainly based on laboratory studies, highlighting the need to shift more toward testing the performance of these remineralizing compounds in clinical settings. [ABSTRACT FROM AUTHOR]

Aims: This paper reviews the oral health services which were available for early (1945–1955) and late (1956–1964) baby boomers, as well as predicts their future oral healthcare needs. Methods and Results: The knowledge, beliefs, and attitudes of the parents of the baby boomers toward dental hygiene and oral healthcare, are reviewed. The introduction of dental health screenings occurred from 1910 to early 1970s, the creation of the first dental hygiene school and the introduction of water fluoridation influenced oral healthcare. Technology introduced in the dental offices in the 1960s included the high‐speed handpiece, followed by intraoral suction in 1979. Baby boomers are keeping their teeth at higher rates than preceding generations due to improved prevention and advances in the treatment of periodontal disease, and overall lower rates of smoking in older adults, when compared to younger adults. However, access to dental care remains an issue for many. Advances in prevention and treatment of periodontal disease, early detection of root caries, new restorative techniques, and improved technologies to replace teeth are also discussed. Conclusions: Early detection of periodontal disease, oral, and oropharyngeal cancer, risk factors for tooth loss and untreated caries are needed to improve the oral health for baby boomers. Access to oral healthcare is still an issue due to socio‐economic disparities in America. [ABSTRACT FROM AUTHOR]

Overcoming the short lifespan of current dental adhesives remains a significant clinical need. Adhesives rely on formation of the hybrid layer to adhere to dentin and penetrate within collagen fibrils. However, the ability of adhesives to achieve complete enclosure of demineralized collagen fibrils is recognized as currently unattainable. We developed a peptide-based approach enabling collagen intrafibrillar mineralization and tested our hypothesis on a type-I collagen-based platform. Peptide design incorporated collagen-binding and remineralization-mediating properties using the domain structure conservation approach. The structural changes from representative members of different peptide clusters were generated for each functional domain. Common signatures associated with secondary structure features and the related changes in the functional domain were investigated by attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and circular dichroism (CD) spectroscopy, respectively. Assembly and remineralization properties of the peptides on the collagen platforms were studied using atomic force microscopy (AFM). Mechanical properties of the collagen fibrils remineralized by the peptide assemblies was studied using PeakForce-Quantitative Nanomechanics (PF-QNM)-AFM. The engineered peptide was demonstrated to offer a promising route for collagen intrafibrillar remineralization. This approach offers a collagen platform to develop multifunctional strategies that combine different bioactive peptides, polymerizable peptide monomers, and adhesive formulations as steps towards improving the long-term prospects of composite resins. [ABSTRACT FROM AUTHOR]

Information on mechanical properties of human enamel and dentin and effect of load on their deformation and damage tolerance is very important in the development of successful dental materials. In this study, the hardness, indentation modulus and deformation characteristics of tooth have been investigated across the lingual–buccal enamel and dentin cross‐section by instrumented indentation up to 1500‐nm indentation depth. We realized and examined the distribution of hardness and modulus at different areas of enamel and dentin with the aim to understand deformation behaviour at these different locations. Scanning electron microscopy was used for the microstructure characterization of the enamel and dentin and their deformation behaviour. Raman spectroscopy analyses were carried out for determination of the enamel and dentin composition as well. The average values of hardness and modulus for enamel in the occlusal area are 5.35 ± 0.19 and 98.1 ± 1.5 GPa, in the inner area 3.68 ± 0.5 and 81.8 ± 5 GPa and in the area close to the dentin–enamel junction 2.83 ± 0.27 and 71.4 ± 4.1 GPa, respectively. The average values of hardness and modulus of dentin in the area close to the dentin–enamel junction are 0.71 ± 0.05 and 21.27 ± 0.76 GPa and in the inner area 0.65 ± 0.06 and 19.79 ± 0.93 GPa, respectively. The effect of the indentation location on deformation and mechanical properties was clarified. [ABSTRACT FROM AUTHOR]

Copyright of Selcuk Dental Journal is the property of Selcuk Dental Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The demineralization process conditions the structure of the enamel and begins with a superficial decalcification procedure that makes the enamel surface porous and gives it a chalky appearance. White spot lesions (WSLs) are the first clinical sign that can be appreciated before caries evolves into cavitated lesions. The years of research have led to the testing of several remineralization techniques. This study's objective is to investigate and assess the various methods for remineralizing enamel. The dental enamel remineralization techniques have been evaluated. A literature search on PubMed, Scopus, and Web of Science was performed. After screening, identification, and eligibility processes 17 papers were selected for the qualitative analysis. This systematic review identified several materials that, whether used singly or in combination, can be effective in the process of remineralizing enamel. All methods have a potential for remineralization when they come into contact with tooth enamel surfaces that have early-stage caries (white spot lesions). From the studies conducted in the test, all of the substances used to which fluoride has been added contribute to remineralization. It is believed that by developing and researching new remineralization techniques, this process might develop even more successfully. [ABSTRACT FROM AUTHOR]

Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical–chemical–structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the remineralization effect of GERM CLEAN, a novel antibacterial peptide, on early enamel caries. Thirty human enamel blocks from thirty teeth were randomly divided into three groups: double distilled water (DDW group), GERM CLEAN (GC group), and 1000 ppm fluoride (NaF group). Specimens were demineralized for 3 days (pH 4.6) followed by pH cycling twice daily for 14 days. For a pH cycle, specimens received corresponding treatments for 5 min, then were immersed in demineralizing solution for 1 h, received corresponding treatments again, and finally were immersed in remineralizing solution (pH 7.0) for approximately 11 h. Specimens were washed with DDW after each treatment. Microindentation tests, atomic force microscopy (AFM), and transverse micro-radiography (TMR) were conducted to analyze enamel blocks. GC demonstrated a lower percentage of surface microhardness recovery (SMHR%) (p < 0.0001), rougher surfaces (p < 0.0001), deeper lesion depth (p = 0.001), and more mineral loss (p = 0.001) than NaF, but showed higher SMHR% (p < 0.0001), smoother surfaces (p < 0.0001), shallower lesion depth (p = 0.049), and less mineral loss (p = 0.001) than DDW. As a result, GERM CLEAN has the potential to promote the remineralization of demineralized enamel. [ABSTRACT FROM AUTHOR]

Ceramic materials in Na2O-CaO-P2O5 system were obtained by firing cement-salt stone made from pastes based on powder mixtures including calcium citrate tetrahydrate Ca3(C6H5O7)2∙4H2O, monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2∙H2O and/or sodium dihydrogen phosphate NaH2PO4. The phase composition of the obtained samples of cement-salt stone after adding water, hardening and drying included brushite CaHPO4∙2H2O, monetite CaHPO4 and also unreacted Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and/or NaH2PO4. The phase composition of ceramics in Na2O-CaO-P2O5 system obtained by firing cement-salt stone was formed due to thermal conversion of hydrated salt and heterophase reactions between components presented in samples during firing. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O and Ca(H2PO4)2∙H2O after firing at 900 °C included β-calcium pyrophosphate (CPP) β-Ca2P2O7. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, and NaH2PO4 after firing at 900 °C included β-sodium rhenanite β-CaNaPO4. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4 after firing at 900 °C included β-Ca2P2O7, β-CaNaPO4, double calcium-sodium pyrophosphate Na2CaP2O7, and Na-substituted tricalcium phosphate Сa10Na(PO4)7. Obtained ceramic materials in Na2O-CaO-P2O5 system including biocompatible and biodegradable phases could be important for treatments of bone tissue defects by means of approaches of regenerative medicine. [ABSTRACT FROM AUTHOR]

Tissue regeneration and remineralization in teeth is a long-term and complex biological process, including the regeneration of pulp and periodontal tissue, and re-mineralization of dentin, cementum and enamel. Suitable materials are needed to provide cell scaffolds, drug carriers or mineralization in this environment. These materials need to regulate the unique odontogenesis process. Hydrogel-based materials are considered good scaffolds for pulp and periodontal tissue repair in the field of tissue engineering due to their inherent biocompatibility and biodegradability, slow release of drugs, simulation of extracellular matrix, and the ability to provide a mineralized template. The excellent properties of hydrogels make them particularly attractive in the research of tissue regeneration and remineralization in teeth. This paper introduces the latest progress of hydrogel-based materials in pulp and periodontal tissue regeneration and hard tissue mineralization and puts forward prospects for their future application. Overall, this review reveals the application of hydrogel-based materials in tissue regeneration and remineralization in teeth. [ABSTRACT FROM AUTHOR]

The biological and mechanical functions of bone rely critically on the inorganic constituent, which can be termed as bone apatite nanocrystal. It features a hydroxylapatite-like crystalline structure, complex chemical compositions (e.g., carbonate-containing and calcium- and hydroxyl-deficient), and fine geometries and properties. The long research with vast literature across broad spectra of disciplines and fields from chemistry, crystallography, and mineralogy, to biology, medical sciences, materials sciences, mechanics, and engineering has produced a wealth of knowledge on the bone apatite nanocrystal. This has generated significant impacts on bioengineering and industrial engineering, e.g., in developing new biomaterials with superior osteo-inductivities and in inspiring novel strong and tough composites, respectively. Meanwhile, confusing and inconsistent understandings on the bone mineral constituent should be addressed to facilitate further multidisciplinary progress. In this review, we present a mineralogical account of the bone-related ideal apatite mineral and then a brief historical overview of bone mineral research. These pave the road to understanding the bone apatite nanocrystal via a material approach encompassing crystalline structure, diverse chemical formulae, and interesting architecture and properties, from which several intriguing research questions emerge for further explorations. Through providing the classical and latest findings with decent clearness and adequate breadth, this review endeavors to promote research advances in a variety of related science and engineering fields. [ABSTRACT FROM AUTHOR]

Introduction: The intracellular Ca2+ sensor stromal interaction molecule 1 (STIM1) is thought to play a critical role in enamel development, as its mutations cause Amelogenesis Imperfecta (AI). We recently established an ameloblast-specific (AmelX-iCre) Stim1 conditional deletion mouse model to investigate the role of STIM1 in controlling ameloblast function and differentiation in vivo (Stim1 cKO). Our pilot data (Said et al., J. Dent. Res., 2019, 98, 1002–1010) support our hypothesis for a broad role of Stim1 in amelogenesis. This paper aims to provide an in-depth characterization of the enamel phenotype observed in our Stim1 cKO model. Methods: We crossed AmelX-iCre mice with Stim1-floxed animals to develop ameloblast-specific Stim1 cKO mice. Scanning electron microscopy, energy dispersive spectroscopy, and micro- CT were used to study the enamel phenotype. RNAseq and RT-qPCR were utilized to evaluate changes in the gene expression of several key ameloblast genes.Immunohistochemistry was used to detect the amelogenin, matrix metalloprotease 20 and kallikrein 4 proteins in ameloblasts. Results: Stim1 cKO animals exhibited a hypomineralized AI phenotype, with reduced enamel volume, diminished mineral density, and lower calcium content. The mutant enamel phenotype was more severe in older Stim1 cKO mice compared to younger ones and changes in enamel volume and mineral content were more pronounced in incisors compared to molars. Exploratory RNAseq analysis of incisors’ ameloblasts suggested that ablation of Stim1 altered the expression levels of several genes encoding enamel matrix proteins which were confirmed by subsequent RT-qPCR. On the other hand, RT-qPCR analysis of molars’ ameloblasts showed non-significant differences in the expression levels of enamel matrix genes between control and Stim1-deficient cells. Moreover, gene expression analysis of incisors’ and molars’ ameloblasts showed that Stim1 ablation caused changes in the expression levels of several genes associated with calcium transport and mitochondrial kinetics. Conclusions: Collectively, these findings suggest that the loss of Stim1 in ameloblasts may impact enamel mineralization and ameloblast gene expression. [ABSTRACT FROM AUTHOR]

Catla collagen hydrolysate (CH) was fractionated by chromatography and each fraction was subjected to HA nucleation, with the resultant HA-fraction composites being scored based on the structural and functional group of the HA formed. The process was repeated till a single peptide with augmented HA nucleation capacity was obtained. The peptide (4.6 kDa), exhibited high solubility, existed in polyproline-II conformation and displayed a dynamic yet stable hierarchical self-assembling property. The 3D modelling of the peptide revealed multiple calcium and phosphate binding sites and a high propensity to self-assemble. Structural analysis of the peptide-HA crystals revealed characteristic diffraction planes of HA with mineralization following the (002) plane, retention of the self-assembled hierarchy of the peptide and intense ionic interactions between carboxyl groups and calcium. The peptide-HA composite crystals were mostly of 25–40 nm dimensions and displayed 79% mineralization, 92% crystallinity, 39.25% porosity, 12GPa Young's modulus and enhanced stability in physiological pH. Cells grown on peptide-HA depicted faster proliferation rates and higher levels of osteogenic markers. It was concluded that the prerequisite for HA nucleation by a peptide included: a conserved sequence with a unique charge topology allowing calcium chelation and its ability to form a dynamic self-assembled hierarchy for crystal propagation. [ABSTRACT FROM AUTHOR]

Marie Ussing Nylen was a trail blazing scientist and administrative leader at the US National Institutes of Health. She accomplished this when it was extremely difficult for a woman to do so. She was also a whole person ‐ a wife, mother, and talented athlete, that is, a well‐rounded person by any definition. She was a gift to dental and oral science, as well as to those fortunate enough to know and work with her. [ABSTRACT FROM AUTHOR]

Calcium phosphates (CaPs) composites with silver nanoparticles (AgNPs) attract attention as a possible alternative to conventional approaches to combating orthopedic implant-associated infections. Although precipitation of calcium phosphates at room temperatures was pointed out as an advantageous method for the preparation of various CaP-based biomaterials, to the best of our knowledge, no such study exists for the preparation of CaPs/AgNP composites. Motivated by this lack of data in this study we investigated the influence of AgNPs stabilized with citrate (cit-AgNPs), poly(vinylpyrrolidone) (PVP-AgNPs), and sodium bis(2-ethylhexyl) sulfosuccinate (AOT-AgNPs) in the concentration range 5–25 mg dm−3 on the precipitation of CaPs. The first solid phase to precipitate in the investigated precipitation system was amorphous calcium phosphate (ACP). The effect of AgNPs on ACP stability was significant only in the presence of the highest concentration of AOT-AgNPs. However, in all precipitation systems containing AgNPs, the morphology of ACP was affected, as gel-like precipitates formed in addition to the typical chain-like aggregates of spherical particles. The exact effect depended on the type of AgNPs. After 60 min of reaction time, a mixture of calcium-deficient hydroxyapatite (CaDHA) and a smaller amount of octacalcium phosphate (OCP) formed. PXRD and EPR data point out that the amount of formed OCP decreases with increasing AgNPs concentration. The obtained results showed that AgNPs can modify the precipitation of CaPs and that CaPs properties can be fine-tuned by the choice of stabilizing agent. Furthermore, it was shown that precipitation can be used as a simple and fast method for CaP/AgNPs composites preparation which is of special interest for biomaterials preparation. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the variant of an amelogenesis imperfecta (AI) family and to explore the function of the FAM83H (family with sequence similarity 83 member H) in the enamel formation. Materials and methods: We investigated a five-generation Chinese family diagnosed with AI; clinical data was collected, whole-exome sequencing (WES) was conducted to explore the pathogenic gene and variants and Sanger sequencing was used to verify the variants. The three-dimensional protein structures of wild-type and mutant FAM83H were predicted using alpha fold 2. To study the possible regulatory function of Fam83h on amelogenesis, immunolocalization was performed to observe the expression of Fam83h protein in Sprague–Dawley rat postnatal incisors. The mRNA and protein level of amelogenin, enamelin, kallikrein-related peptidase-4 and ameloblastin were also detected after the Fam83h was knocked down by small interfering RNA (siRNA) in HAT-7 cells. Results: A known nonsense variant (c.973 C > T) in exon 5 of FAM83H gene was found in this family, causing a truncated protein (p.R325X). Immunolocalization of Fam83h in Sprague–Dawley rat postnatal incisors showed that Fam83h protein expression was detected in presecretory and secretory stages. When Fam83h expression was reduced by siRNA, the expression of amelogenin, enamelin, kallikrein-related peptidase-4 decreased. However, the expression of ameloblastin increased. Conclusions: FAM83H gene variant (c.973 C > T) causes AI. FAM83H regulates the secretion of enamel matrix proteins and affects ameloblast differentiation. Clinical relevance: This study provided that FAM83H variants could influence enamel formation and provided new insights into the pathogenesis of AI. [ABSTRACT FROM AUTHOR]

With the gradual discovery of functional domains in natural proteins, several biologically inspired peptides have been designed for use as biomaterials for hard tissue regeneration and repair. In this study, we designed a tuftelin-derived peptide (TDP) and tested its effects on hydroxyapatite crystallization and remineralization of initial enamel carious lesions in vitro. Using circular dichroism spectroscopy, we found that TDP contained 36.1% β-sheets and β-turns, which could be influenced by calcium ions. We verified the ability of TDP to crystallize hydroxyapatite using transmission electron microscopy and its ability to bind to the enamel surface and hydroxyapatite using confocal laser scanning microscopy and Langmuir adsorption isotherms (K = 881.56, N = 1.41 × 10 -5 ). Artificial enamel lesions were generated on human enamel blocks and subjected to a 12-day pH cycling model and were treated with 25 μM TDP, 1 g/L sodium fluoride (NaF), or deionized water. We analyzed the results of remineralization by surface microhardness testing, polarized light microscopy, and transverse microradiography. The TDP group showed significantly higher surface microhardness recovery (49.21 ± 1.66%), shallower lesions (34.89 ± 4.05 μm), and less mineral loss (871.33 ± 81.49 vol%·μm) after pH cycling than the deionized water group (p < .05). There were no significant differences between the TDP and NaF groups. Our experiment indicated that TDP could regulate hydroxyapatite crystallization and promote remineralization of enamel caries in vitro., (© 2020 Wiley Periodicals, Inc.)

In situ regeneration of the enamel-like structure of hydroxyapatite (HAp) crystals under oral conditions is significant for dental caries treatment. However, it is still a challenge for dentists to duplicate the elegant and well-aligned apatite structure bonding to the surface of demineralized enamel. A biocompatible amelogenin-inspired matrix, a phase-transited lysozyme (PTL) film mimicking an N-terminal amelogenin with central domain (N-Ame) combined with synthetic peptide (C-AMG) based on the functional domains of C-terminal telopeptide (C-Ame) is shown here, which is formed by amyloid-like lysozyme aggregation at the enamel interface through a rapid one-step aqueous coating process. In the PTL/C-AMG matrix, C-AMG facilitated the oriented arrangement of amorphous calcium phosphate (ACP) nanoparticles and their transformation to ordered enamel-like HAp crystals, while PTL served as a strong interfacial anchor to immobilize the C-AMG peptide and PTL/C-AMG matrix on versatile substrate surfaces. PTL/C-AMG film-coated enamel induced both of the in vivo and in vitro synthesis of HAp crystals, facilitated epitaxial growth of HAp crystals and recovered the highly oriented structure and mechanical properties to levels nearly identical to those of natural enamel. This work underlines the importance of amyloid-like protein aggregates in the biomineralization of enamel, providing a promising strategy for treating dental caries., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sex estimation of skeletons is fundamental to many archaeological studies. Currently, three approaches are available to estimate sex-osteology, genomics, or proteomics, but little is known about the relative reliability of these methods in applied settings. We present matching osteological, shotgun-genomic, and proteomic data to estimate the sex of 55 individuals, each with an independent radiocarbon date between 2,440 and 100 cal BP, from two ancestral Ohlone sites in Central California. Sex estimation was possible in 100% of this burial sample using proteomics, in 91% using genomics, and in 51% using osteology. Agreement between the methods was high, however conflicts did occur. Genomic sex estimates were 100% consistent with proteomic and osteological estimates when DNA reads were above 100,000 total sequences. However, more than half the samples had DNA read numbers below this threshold, producing high rates of conflict with osteological and proteomic data where nine out of twenty conditional DNA sex estimates conflicted with proteomics. While the DNA signal decreased by an order of magnitude in the older burial samples, there was no decrease in proteomic signal. We conclude that proteomics provides an important complement to osteological and shotgun-genomic sex estimation.

Previously we detected increased levels of IgA to the enamel matrix protein amelogenin in children with untreated coeliac disease (CeD). The biological impact of autoantibodies to amelogenin may depend on which part of the amelogenin (epitopes) they bind. Sera or blood samples from 146 untreated children with CeD from two different cohorts and 25 non-CeD control children were tested for IgA anti-amelogenin (Emdogain) reactivity. The 32 CeD children and six controls with the highest reactivity were selected for detailed IgA anti-amelogenin (AMELX) epitope mapping using 31 overlapping, 10-22mer peptides in ELISA. The dominating reactivity were to six peptides in a 75-amino-acid (aa)-long central segment (aa 75-150) containing enzymatic cleavage sites for matrix metalloproteinase 20 (MMP-20) and kallikrein-related peptidase 4 (KLK-4) and to two N-terminal peptides (aa 13-41) included in the tyrosine-rich amelogenin peptide fragment, which is important for self-assembly. Only two of the six control children reacted to single, but different peptides. Solid-phase extraction with gliadin- and Emdogain-coated Sepharose revealed a gliadin cross-reactive central region and a putative conformation-dependent, apparently non-cross-reactive N-terminal region. High IgA anti-amelogenin reactivity may interfere with normal amelogenesis by inhibiting amelogenin self-assembly, amelogenin-hydroxyapatite interaction, and/or enzymatic degradation., (© 2020 The Authors. Eur J Oral Sci published by John Wiley & Sons Ltd.)

This study aimed to assess the in vitro effects of re-irradiation on enamel and dentin properties, simulating head and neck cancer radiotherapy retreatment. Forty-five human permanent molars were classified into five groups: non-irradiated; irradiated 60 Gy, and re-irradiated with doses of 30, 40, and 50 Gy. Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) were employed for analysis. Raman spectroscopy assessed intensity, spectral area, and specific peaks comparatively. Statistical analysis involved Kolmogorov-Smirnov and One-Way ANOVA tests, with Tukey's post-test (significance level set at 5%). Significant changes in irradiated, non-irradiated, and re-irradiated enamel peaks were observed, including phosphate (438 nm), hydroxyapatite (582 nm), phosphate (960 nm), and carbonate (1070 nm) (p < 0.05). Re-irradiation affected the entire tooth (p > 0.05), leading to interprismatic region degradation, enamel prism destruction, and hydroxyapatite crystal damage. Dentin exhibited tubule obliteration, crack formation, and progressive collagen fiber fragmentation. EDX revealed increased oxygen percentage and decreased phosphorus and calcium post-reirradiation. It is concluded that chemical and morphological changes in irradiated permanent teeth were dose-dependent, exacerbated by re-irradiation, causing substantial damage in enamel and dentin., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Epigenetic regulation plays important role in stem cell maintenance. Ptip was identified as epigenetic regulator, but the role in dental progenitor cells remains unclear., Subjects and Methods: Dental mesenchymal progenitor cells were targeted by Sp7-icre and visualized in mTmG; Sp7-icre mice. The Ptip f/f ; Sp7-icre mice were generated and the phenotype of incisors and molars were shown by micro-computerized tomography, scanning electron microscope, hematoxylin & eosin staining, and immunofluorescence. Dental mesenchymal progenitor cells were sorted by fluorescence-activated cell sorting from lower incisors and RNA sequencing was performed., Results: The Sp7-icre targets dental mesenchymal progenitor cells in incisors and molars. The Ptip f/f ; Sp7-icre mice showed spontaneous fractures in the cusp of upper incisors and lower incisors at 3 weeks (w), compensative overgrowth of lower incisors at 1 month (M), and overgrowth extended to the outside at 2 M. The molars showed shortened roots. The functions of odontoblasts and dental mesenchymal progenitor cells were impaired. Mechanically, loss of Ptip activates the Wnt pathway and upregulates the expression of Wls in dental mesenchymal progenitor cells. Also, the regenerative ability of lower incisors was significantly impaired., Conclusion: We first demonstrated that Ptip was crucial for tooth development via regulating Wnt signaling., (© 2023 Wiley Periodicals LLC.)

Purpose: To assess the remineralising efficacy of fluoride varnish containing additives and conventional sodium fluoride varnish.Materials and Methods: 72 extracted upper central incisors specimens were randomly allocated to four groups after demineralisation: control; 5% sodium fluoride varnish (FV) (Fluoritop-SR); resin modified glass ionomer-based calcium phosphate containing fluoride varnish (CV) (Clinpro XT); fluoride varnish with xylitol coated calcium phosphate (cXp) (Embrace). Change in surface morphology, calcium phosphorous ratio and fluoride content of enamel were evaluated using scanning electron microscope and energy dispersive X-ray analysis (SEM-EDAX). Change in surface roughness was evaluated using profilometer analysis. All readings were taken at baseline, after demineralisation, at 2 weeks and 4 weeks of remineralisation.Results: At 4 weeks of remineralisation surface roughness values were ranked as follows: control > FV = cXp > CV. Calcium phosphorus ratios were in the order: CV > FV = cXp > control and fluoride content (for treatment groups): CV = cXp > FV. Scanning electron microscopy images showed mineral deposition on the surfaces of the treatment groups with different deposition pattern of minerals.Conclusion: Fluoride varnishes with or without additives are effective in remineralisation of early enamel lesions. Glass ionomer-based fluoride varnish results in better remineralisation than xylitol coated calcium phosphate containing fluoride varnish and 5% sodium fluoride varnish. [ABSTRACT FROM AUTHOR]

Continuously growing mouse incisors are widely used to study amelogenesis, since all stages of this process (i.e., secretory, transition and maturation) are present in a spatially determined sequence at any given time. To study biological changes associated with enamel formation, it is important to develop reliable methods for collecting ameloblasts, the cells that regulate enamel formation, from different stages of amelogenesis. Micro-dissection, the key method for collecting distinct ameloblast populations from mouse incisors, relies on positions of molar teeth as landmarks for identifying critical stages of amelogenesis. However, the positions of mandibular incisors and their spatial relationships with molars change with age. Our goal was to identify with high precision these relationships throughout skeletal growth and in older, skeletally mature animals. Mandibles from 2, 4, 8, 12, 16, and 24-week-old, and 18-month-old C57BL/6J male mice, were collected and studied using micro-CT and histology to obtain incisal enamel mineralization profiles and to identify corresponding changes in ameloblast morphology during amelogenesis with respect to positions of molars. As reported here, we have found that throughout active skeletal growth (weeks 2–16) the apices of incisors and the onset of enamel mineralization move distally relative to molar teeth. The position of the transition stage also moves distally. To test the accuracy of the landmarks, we micro-dissected enamel epithelium from mandibular incisors of 12-week-old animals into five segments, including 1) secretory, 2) late secretory - transition - early maturation, 3) early maturation, 4) mid-maturation and 5) late maturation. Isolated segments were pooled and subjected to expression analyses of genes encoding key enamel matrix proteins (EMPs), Amelx, Enam, and Odam, using RT-qPCR. Amelx and Enam were strongly expressed during the secretory stage (segment 1), while their expression diminished during transition (segment 2) and ceased in maturation (segments 3, 4, and 5). In contrast, Odam’s expression was very low during secretion and increased dramatically throughout transition and maturation stages. These expression profiles are consistent with the consensus understanding of enamel matrix proteins expression. Overall, our results demonstrate the high accuracy of our landmarking method and emphasize the importance of selecting age-appropriate landmarks for studies of amelogenesis in mouse incisors. [ABSTRACT FROM AUTHOR]

Enamel development is a process in which extracellular matrix models from a soft proteinaceous matrix to the most mineralized tissue in vertebrates. Patients with mutant NCKX4, a gene encoding a K+-dependent Na+/Ca2+--exchanger, develop a hypomineralized and hypomature enamel. How NCKX4 regulates enamel protein removal to achieve an almost protein-free enamel is unknown. We characterized the upregulation pattern of Nckx4 in the progressively differentiating enamel-forming ameloblasts by qPCR, and as well as confirmed NCKX4 protein to primarily localize at the apical surface of wild-type ruffle-ended maturation ameloblasts by immunostaining of the continuously growing mouse incisors, posing the entire developmental trajectory of enamel. In contrast to the normal mature enamel, where ECM proteins are hydrolyzed and removed, we found significant protein retention in thematuration stage of Nckx4-/- mouse enamel. The Nckx4-/- enamel held less Ca2+ and K+ but more Na+ than the Nckx4+/+ enamel did, as measured by EDX. The alternating acidic and neutral pH zones at the surface of mineralizing Nckx4+/+ enamel were replaced by a largely neutral pH matrix in the Nckx4-/- enamel. In situ zymography revealed a reduced kallikrein-related peptidase 4 (KLK4) activity in the Nckx4-/- enamel. We showed that KLK4 took on 90% of proteinase activity in the maturation stage of normal enamel, and that recombinant KLK4 as well as native mouse enamel KLK4 both performed less effectively in a buffer with increased [Na+] and pH, conditions found in the Nckx4-/- developing enamel. This study, for the first time to our knowledge, provides evidence demonstrating the impaired in situ KLK4 activity in Nckx4-/- enamel and suggests a novel function of NCKX4 in facilitating KLK4-mediated hydrolysis and removal of ECM proteins, warranting the completion of enamel matrix modeling. [ABSTRACT FROM AUTHOR]

Oral and maxillofacial diseases have an important impact on local function, facial appearance, and general health. As a multifunctional platform, hydrogels are widely used in the biomedical field due to their excellent physicochemical properties. In recent years, a large number of studies have been conducted to adapt hydrogels to the complex oral and maxillofacial environment by modulating their pore size, swelling, degradability, stimulus-response properties, etc. Meanwhile, many studies have attempted to use hydrogels as drug delivery carriers to load drugs, cytokines, and stem cells for antibacterial, anticancer, and tissue regeneration applications in oral and maxillofacial regions. This paper reviews the application and research progress of hydrogel-based drug delivery systems in the treatment of oral and maxillofacial diseases such as caries, endodontic diseases, periodontal diseases, maxillofacial bone diseases, mucosal diseases, oral cancer, etc. The characteristics and applications of hydrogels and drug-delivery systems employed for the treatment of different diseases are discussed in order to provide a reference for further research on hydrogel drug-delivery systems in the future. [ABSTRACT FROM AUTHOR]

Dental caries is one of the most common human diseases which can occur in both primary and permanent dentitions throughout the life of an individual. Hydroxyapatite is the major inorganic component of human teeth, consequently, nanosized hydroxyapatite (nHAP) has recently attracted researchers' attention due to its unique properties and potential for caries management. This article provides a contemporary review of the potential beneficial effects of nHAP on caries lesions demonstrated in in vitro studies. Data showed that nHAP has potential to promote mineralization in initial caries, by being incorporated into the porous tooth structure, which resulted from the caries process, and subsequently increased mineral content and hardness. Notably, it is the particle size of nHAP which plays an important role in the mineralization process. Antimicrobial effects of nHAP can also be achieved by metal substitution in nHAP. Dual action property (mineralizing and antimicrobial) and enhanced chemical stability and bioactivity of nHAP can potentially be obtained using metal-substituted fluorhydroxyapatite nanoparticles. This provides a promising synergistic strategy which should be explored in further clinical research to enable the development of dental therapeutics for use in the treatment and management of caries. [ABSTRACT FROM AUTHOR]

Amelogenin constitutes ~90% of the enamel matrix in the secretory stage of amelogenesis, a still poorly understood process that results in the formation of the hardest and most mineralized tissue in vertebrates—enamel. Most biophysical research with amelogenin uses recombinant protein expressed in Escherichia coli. In addition to providing copious amounts of protein, recombinant expression allows 13C‐ and 15N‐labeling for detailed structural studies using NMR spectroscopy. However, native amelogenin is phosphorylated at one position, Ser‐16 in murine amelogenin, and there is mounting evidence that Ser‐16 phosphorylation is important. Using a modified genetic code expansion protocol we have expressed and purified uniformly 13C‐, 15N‐labeled murine amelogenin (pS16M179) with ~95% of the protein being correctly phosphorylated. Homogeneous phosphorylation was achieved using commercially available, enriched, 13C‐, 15N‐labeled media, and protein expression was induced with isopropyl β‐D‐1‐thiogalactopyranoside at 310 K. Phosphoserine incorporation was verified from one‐dimensional 31P NMR spectra, comparison of 1H‐15N HSQC spectra, Phos‐tag SDS PAGE, and mass spectrometry. Phosphorus‐31 NMR spectra for pS16M179 under conditions known to trigger amelogenin self‐assembly into nanospheres confirm nanosphere models with buried N‐termini. Lambda phosphatase treatment of these nanospheres results in the dephosphorylation of pS16M179, confirming that smaller oligomers and monomers with exposed N‐termini are in equilibrium with nanospheres. Such 13C‐, 15N‐labeling of amelogenin with accurately encoded phosphoserine incorporation will accelerate biomineralization research to understand amelogenesis and stimulate the expanded use of genetic code expansion protocols to introduce phosphorylated amino acids into proteins. [ABSTRACT FROM AUTHOR]

Highly specialized enamel matrix proteins (EMPs) are predominantly expressed in odontogenic tissues and diverged from common ancestral gene. They are crucial for the maturation of enamel and its extreme complexity in multiple independent lineages. However, divergence of EMPs occured already before the true enamel evolved and their conservancy in toothless species suggests that non-canonical functions are still under natural selection. To elucidate this hypothesis, we carried out an unbiased, comprehensive phenotyping and employed data from the International Mouse Phenotyping Consortium to show functional pleiotropy of amelogenin, ameloblastin, amelotin, and enamelin, genes, i.e. in sensory function, skeletal morphology, cardiovascular function, metabolism, immune system screen, behavior, reproduction, and respiratory function. Mice in all KO mutant lines, i.e. amelogenin KO, ameloblastin KO, amelotin KO, and enamelin KO, as well as mice from the lineage with monomeric form of ameloblastin were affected in multiple physiological systems. Evolutionary conserved motifs and functional pleiotropy support the hypothesis of role of EMPs as general physiological regulators. These findings illustrate how their non-canonical function can still effect the fitness of modern species by an example of influence of amelogenin and ameloblastin on the bone physiology. [ABSTRACT FROM AUTHOR]

Objective: To explore the regulatory effect of recombinant amelogenin peptide TRAP on the remineralization of early enamel carious lesions. Methods: Forty-eight bovine enamel blocks that prepared initial lesions in vitro were split at random into four groups for immersion treatment for 12 days: 1) remineralizing medium; 2) studied peptide 1 (consisting of the N- and C-termini of porcine amelogenin) + remineralizing medium; 3) studied peptide 2 (TRAP) + remineralizing medium; 4) fluoride + remineralizing medium. After demineralization and remineralization immersion, each specimen’s mean mineral loss and lesion depth were measured using micro-computed tomography (micro-CT). The changes in lesion depth (ΔLD) and mineral gain (ΔZ) were computed following remineralization. The enamel samples were then cut into sections and examined with polarized light microscopy (PLM). The cross-section morphology was observed by scanning electron microscopy (SEM). The crystal phase was analyzed by an X-ray micro-diffractometer (XRD). The calcium-binding properties were determined using isothermal titration calorimetry (ITC). Results: Micro-CT analysis revealed a significant reduction in mineral loss in the four groups following the remineralization treatment (p < 0.05). The treatment with fluoride resulted in the greatest ΔZ and ΔLD, whereas the treatment with a remineralizing medium showed the least ΔZ and ΔLD among all groups. The ΔZ and ΔLD of the studied peptide 1 and studied peptide 2 groups were greater than those of the remineralizing medium group. However, there was no significant difference between the studied peptide 1 and studied peptide 2 groups (p > 0.05). All of the samples that the PLM analyzed had a thickening of the surface layer. A negative birefringent band changed in the lesion’s body. The SEM displayed that minerals were formed in all four groups of samples. The XRD results indicated that the products of remineralization of the studied peptide were hydroxyapatite crystals (HA). ITC showed that there were two binding modes between the calcium and peptide TRAP. Conclusion: This study confirmed the potential of the recombinant amelogenin peptide TRAP as a key functional motif of amelogenin protein for enamel remineralization and provided a promising biomaterial for remineralization in initial enamel carious lesion treatment. [ABSTRACT FROM AUTHOR]

In this study, luminescence and antibacterial behavior of pure fluorapatite (FAp) and praseodymium-nitrate-carbonate co-doped fluorapatite (PrNCFAp) nanopowders were investigated. Uniform nanopowders were synthesized by precipitation reaction followed by centrifugation and systematically characterized by XRD, FTIR, SEM–EDS, TG and PL methods. XRD analysis revealed the formation of hexagonal FAp crystals, and FTIR spectra indicate the presence of nitrate (NO3−) and carbonate (CO32−) species. SEM analyzes confirm agglomerates composed of irregular nanometer-sized spheres. Emission of FAp nanopowder occurred in the violet-blue region of the visible part of the spectrum, with redshift to the blue-green color region when Pr3+, NO3− and CO32− co-doped in the lattice. Analysis of luminescence spectra by MCR-ALS method extract three fluorophores from the PrNCFAp sample and showed simultaneous existents of emission-reabsorption-emission between dopants in FAp lattice. Antibacterial activity against pathogen Staphylococcus aureus was investigated before and after treatment of nanopowders by UVA radiation of 365 nm. Nanopowders irradiated with UVA compared to non-irradiated reduced Staphylococcus aureus by 84.9% for PrNCFAp and 33.3% for FAp in the first 0.5 h of contact, and 76.1% and 42.9% after 24 h of contact. In addition, the obtained luminescent nanomaterials showed a low degree of hemolytic activity and could potentially be candidates for further research in dentistry. [ABSTRACT FROM AUTHOR]

Enamel is the outermost layer of the tooth and has no ability to regenerate after tooth eruption. Its mineral composition is likely to be responsible for the enamel resistance to any agents that appear in oral cavity. The objective of this study was to compare the content of Ca, Mg, Zn and Cu in specific layers of healthy and worn tooth enamel. Three groups of dental enamel samples were analyzed. The amounts of Ca, Mg and Zn in the enamel bioptates were established using atomic absorption spectroscopy after an acid biopsy technique had been applied. The concentration of Cu was established using an electrothermic method with an AA spectrometer. The analysis was carried out using parametric tests (the Pearson's linear correlation coefficient and the t-test for the correlation coefficient). Results: A statistically significant difference was confirmed between the mean amount of zinc in severely worn dentition and all the layers in vitro and in vivo. Strong positive relationships between magnesium and zinc contents were shown at some depths. A significant difference was registered between the amount of copper in the severely worn dentitions compared to the superficial layer of the healthy teeth in vitro and in vivo. Conclusion: It appears that zinc metabolism may play an important role in enamel formation and may influence enamel's resistance to wear after tooth eruption. [ABSTRACT FROM AUTHOR]

A proline-rich region was found in Streptococcus mutans (S. mutans) surface antigen I/II (Ag I/II). The functions of this region were explored to determine its role in the cariogenic abilities of S. mutans; specifically, the proline-rich region was compared with human amelogenin. The full-length amelogenin genes were cloned from human (AmH) and surface antigen I/II genes from S. mutans. Then, the genes expressed and purified. We analyzed the structure and self-assembly ability of AmH and Ag I/II, compared their capacities to induce mineralization, and assessed the adhesion ability of S. mutans to AmH- and Ag I/II-coated tooth slices. AmH formed ordered chains and net frames in the early stage of protein self-assembly, while Ag I/II formed irregular and overlapping structures. AmH induced mineralization possessed a parallel rosary structure, while Ag I/II-induced mineralization is rougher and more irregular. The S. mutans adhesion assay indicated that the adhesion ability S. mutans on the Ag I/II-induced crystal layer was significantly higher than that on the AmH-induced crystal layer. S. mutans' Ag I/II may have evolved to resemble human amelogenin and form a rougher crystal layer on teeth, which play a competitive mineralization role and promotes better bacterial adhesion and colonization. Thus, the cariogenic ability of S. mutans Ag I/II is increased. [ABSTRACT FROM AUTHOR]

Recent advances in atomic force microscopy (AFM) have allowed the characterisation of dental‐associated biomaterials and biological surfaces with high resolution. In this context, the topography of dental enamel – the hardest mineralised tissue in the body – has been explored with AFM‐based approaches at the microscale. With age, teeth are known to suffer changes that can impact their structural stability and function; however, changes in enamel structure because of ageing have not yet been explored with nanoscale resolution. Therefore, the aim of this exploratory work was to optimise an approach to characterise the ultrastructure of dental enamel and determine potential differences in topography, hydroxyapatite (HA) crystal size, and surface roughness at the nanoscale associated to ageing. For this, a total of six teeth were collected from human donors from which enamel specimens were prepared. By employing intermittent contact (AC mode) imaging, HA crystals were characterised in both transversal and longitudinal orientation (respect to surface plane) with high resolution in environmental conditions. The external enamel surface displayed the presence of a pellicle‐like coating on its surface that was not observable on cleaned specimens. Acid‐etching exposed crystals that were imaged and morphologically characterised in high resolution at the nanoscale in both the external and internal regions of enamel in older and younger specimens. Our results demonstrated important individual variations in HA crystal width and roughness parameters across the analysed specimens; however, an increase in surface roughness and decrease in HA width was observed for the pooled older external enamel group compared to younger specimens. Overall, high‐resolution AFM was an effective approach for the qualitative and quantitative characterisation of human dental enamel ultrastructure. Future work should focus on exploring the ageing of dental enamel with increased sample sizes to compensate for individual differences as well as other potential confounding factors such as behavioural habits and mechanical forces. Lay description: Currently, advanced microscopy techniques such as atomic force microscopy (AFM) can be used to characterise surfaces relevant to dentistry with great detail. Among these surfaces of interest, dental enamel – the hardest mineralised tissue in the body – is important as it protects the deeper areas of the tooth from harmful stimuli such as sudden temperature changes, bacterial penetration, and chemical attack. Also, dental enamel is an important surface for the adhesion of some types of dental restorations; thus, its structure and organisation is highly relevant for both dental scientists and clinicians. With age, teeth are known to suffer changes that can impact their structural stability and function; however, changes in enamel structure as a result of ageing have not yet been explored with nanoscale resolution. It is necessary to develop and optimise AFM‐based techniques in order to process specimens from dental samples across different age groups for ageing‐associated nanoscale studies in the future. Therefore, the aim of this investigation was to optimise an approach to characterise the ultrastructure of dental enamel and determine potential differences in enamel topography, hydroxyapatite (HA) crystal size, and surface roughness at the nanoscale associated to ageing. For this, human enamel specimens obtained from a total of six teeth were collected and analysed with AFM, and HA crystals were characterised in both transversal and longitudinal orientation with high resolution in environmental conditions. Upon AFM observation, sound superficial enamel displayed the presence of a pellicle‐like coating on its surface, that was not observable after specimens were cleaned. Furthermore, acid‐etching exposed HA crystals that were imaged and morphologically characterised in high resolution at the nanoscale across different regions of enamel in older and younger specimens. We observed important individual variations in HA crystal width and roughness parameters across the analysed specimens and groups, suggesting individual as well as age‐associated differences. Overall, high‐resolution AFM was an effective approach for the qualitative and quantitative characterisation of human dental enamel ultrastructure at the nanometre range with minimal sample preparation. This proof‐of‐concept work can pave the way for future studies employing increased sample sizes to compensate for individual differences and population level factors. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the effects of octacalcium phosphate (OCP)-induced bone regeneration on angiogenesis regulated by the inclusion of copper ions in OCP in vitro and in vivo. Calcium (Ca)-deficient Cu-OCPs, containing 0.01 wt% Cu (low-Cu-OCP) and 0.12 wt % Cu (high-Cu-OCP), were synthesized with co7pper gluconate salt. The lattice parameters of Cu-OCPs tended to decrease slightly with Cu inclusion, as estimated by Rietveld analysis. Cu ions were released in OCP when the materials were incubated in the medium for human umbilical vein endothelial cells (HUVECs). The solubility of Cu-OCPs, estimated by the degree of supersaturation, was slightly higher than that of the original OCP. Cu-OCP tended to hydrolyze to an apatite structure while maintaining the crystal plate-like morphology when incubated with mesenchymal stem D1 cells in osteogenic media for 14 days. The specimens were characterized by selected area electron diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. Low-Cu-OCP significantly enhanced the HUVEC capillary cross-linking density. D1 cell differentiation was inhibited with the inclusion of Cu, even at low concentrations. The composite of low-Cu-OCP with a gelatin sponge (low-Cu-OCP/Gel) significantly enhanced angiogenesis coupled with bone regeneration when implanted in a rat calvarial critical-sized defect for 4 weeks, compared with the corresponding amount of Cucontaining Gel (Cu/Gel) or OCP/Gel materials through angiography and tissue histomorphometry. These results support the proposition that angiogenesis stimulated by low-Cu-OCP is closely related with enhanced bone regeneration. [ABSTRACT FROM AUTHOR]

The distinct morphology adopted by ameloblasts during amelogenesis is highly stage specific and involved intimately with the development of a hierarchical enamel microstructure. The molecular mechanisms that govern the development of an elongated and polarized secretory ameloblast morphology and the potential roles played by the enamel matrix proteins in this process are not fully understood. Thus far, the in vitro models that have been developed to mimic these early cell-matrix interactions have either been unable to demonstrate direct morphological change or have failed to adapt across ameloblast cell lines. Here, we use a recently established 3D cell culture model to examine the interactions between HAT-7 cells and the major enamel matrix proteins, amelogenin and ameloblastin. We demonstrate that HAT-7 cells selectively respond to functional EMPs in culture by forming clusters of tall cells. Aspect ratio measurements from three-dimensional reconstructions reveal that cell elongation is 5-times greater in the presence of EMPs when compared with controls. Using confocal laser scanning microscopy, we observe that these clusters are polarized with asymmetrical distributions of Par-3 and claudin-1 proteins. The behavior of HAT-7 cells in 3D culture with EMPs is comparable with that of ALC and LS-8 cells. The fact that the 3D model presented here is tunable with respect to gel substrate composition and ameloblast cell type highlights the overall usefulness of this model in studying ameloblast cell morphology in vitro. [ABSTRACT FROM AUTHOR]

The transition in Mysticeti (Cetacea) from capture of individual prey using teeth to bulk filtering batches of small prey using baleen ranks among the most dramatic evolutionary transformations in mammalian history. We review phylogenetic work on the homology of mysticete feeding structures from anatomical, ontogenetic, and genomic perspectives. Six characters with key functional significance for filter-feeding behavior are mapped to cladograms based on 11 morphological datasets to reconstruct evolutionary change across the teeth-to-baleen transition. This comparative summary within a common parsimony framework reveals extensive conflicts among independent systematic efforts but also broad support for the newly named clade Kinetomenta (Aetiocetidae + Chaeomysticeti). Complementary anatomical studies using CT scans and ontogenetic series hint at commonalities between the developmental programs for teeth and baleen, lending further support for a 'transitional chimaeric feeder' scenario that best explains current evidence on the transition to filter feeding. For some extant mysticetes, the ontogenetic sequence in fetal specimens recapitulates the inferred evolutionary transformation: from teeth, to teeth and baleen, to just baleen. Phylogenetic mapping of inactivating mutations reveals mutational decay of 'dental genes' related to enamel formation before the emergence of crown Mysticeti, while 'baleen genes' that were repurposed or newly derived during the evolutionary elaboration of baleen currently are poorly characterized. Review and meta-analysis of available data suggest that the teeth-to-baleen transition in Mysticeti is one of the best characterized macroevolutionary shifts due to the diversity of data from the genome, the fossil record, comparative anatomy, and ontogeny that directly bears on this remarkable evolutionary transformation. [ABSTRACT FROM AUTHOR]

Milk caseins and dental amelogenins are intrinsically disordered proteins (IDPs) that associate with themselves and others. Paradoxically, they are also described as hydrophobic proteins, which is difficult to reconcile with a solvent-exposed conformation. We attempt to resolve this paradox. We show that caseins and amelogenins are not hydrophobic proteins but they are more hydrophobic than most IDPs. Remarkably, uncharged residues from different regions of these mature proteins have a nearly constant average hydropathy but these regions exhibit different charged residue frequencies. A novel sequence analysis method was developed to identify hydrophobic and order-promoting regions that would favor conformational collapse. We found that such regions were uncommon; most hydrophobic and order-promoting residues were adjacent to hydrophilic or disorder-promoting residues. A further reason why caseins and amelogenins do not collapse is their high proportion of disorder-promoting proline residues. We conclude that in these proteins the hydrophobic effect is not large enough to cause conformational collapse but it can contribute, along with polar interactions, to protein-protein interactions. This behaviour is similar to the interaction of the disordered N-terminal region of small heat-shock proteins with either themselves during oligomer formation or other, unfolding, proteins during chaperone action., (© 2019 Wiley Periodicals, Inc.)

The study of protein aggregation, and amyloidosis in particular, has gained considerable interest in recent times. Several neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's (PD) show a characteristic buildup of proteinaceous aggregates in several organs, especially the brain. Despite the enormous upsurge in research articles in this arena, it would not be incorrect to say that we still lack a crystal-clear idea surrounding these notorious aggregates. In this review, we attempt to present a holistic picture on protein aggregation and amyloids in particular. Using a chronological order of discoveries, we present the case of amyloids right from the onset of their discovery, various biophysical techniques, including analysis of the structure, the mechanisms and kinetics of the formation of amyloids. We have discussed important questions on whether aggregation and amyloidosis are restricted to a subset of specific proteins or more broadly influenced by the biophysiochemical and cellular environment. The therapeutic strategies and the significant failure rate of drugs in clinical trials pertaining to these neurodegenerative diseases have been also discussed at length. At a time when the COVID-19 pandemic has hit the globe hard, the review also discusses the plausibility of the far-reaching consequences posed by the virus, such as triggering early onset of amyloidosis. Finally, the application(s) of amyloids as useful biomaterials has also been discussed briefly in this review. [ABSTRACT FROM AUTHOR]

The oral cavity is an environment with diverse bacteria; thus, antibacterial materials are crucial for treating and preventing dental diseases. There is a high demand for materials with an enamel-like architecture because of the high failure rate of dental restorations, due to the physical differences between dental materials and enamel. However, recreating the distinctive apatite composition and hierarchical architecture of enamel is challenging. The aim of this study was to synthesize a novel material with an enamel-like structure and antibacterial ability. We established a non-cell biomimetic method of evaporation-based bottom-up self-assembly combined with a layer-by-layer technique and introduced an antibacterial agent (graphene oxide) to fabricate a biofunctional material with an enamel-like architecture and antibacterial ability. Specifically, enamel-like graphene oxide-hydroxyapatite crystals, formed on a customized mineralization template, were assembled into an enamel-like prismatic structure with a highly organized orientation preferentially along the c-axis through evaporation-based bottom-up self-assembly. With the aid of layer-by-layer absorption, we then fabricated a bulk macroscopic multilayered biofunctional material with a hierarchical enamel-like architecture. This enamel-inspired biomaterial could effectively resolve the problem in dental restoration and brings new prospects for the synthesis of other enamel-inspired biomaterials. [ABSTRACT FROM AUTHOR]

Oral health is vital to general health and well-being for all ages, and as with other chronic conditions, oral health problems increase with age. There is a bi-directional link between nutrition and oral health, in that nutrition affects the health of oral tissues and saliva, and the health of the mouth may affect the foods consumed. Evidence suggests that a healthy diet generally has a positive impact on oral health in older adults. Although studies examining the direct link between oral health and protein intake in older adults are limited, some have explored the relationship via malnutrition, which is also prevalent among older adults. Protein–energy malnutrition (PEM) may be associated with poor oral health, dental caries, enamel hypoplasia, and salivary gland atrophy. This narrative review presents the theoretical evidence on the impact of dietary protein and amino acid composition on oral health, and their combined impact on overall health in older adults. [ABSTRACT FROM AUTHOR]

To investigate correlation between the ameloblastin (Ambn) amino acid sequence and the emergence of prismatic enamel, a notable event in the evolution of ectodermal hard tissues, we analyzed Ambn sequences of 53 species for which enamel microstructures have been previously reported. We found that a potential amphipathic helix (AH) within the sequence encoded by Exon 5 of Ambn appeared in species with prismatic enamel, with a few exceptions. We studied this correlation by investigating synthetic peptides from different species. A blue shift in fluorescence spectroscopy suggested that the peptides derived from mammalian Ambn interacted with liposomes. A downward shift at 222 nm in circular dichroism spectroscopy of the peptides in the presence of liposomes suggested that the peptides of mammals with prismatic enamel underwent a transition from disordered to helical structure. The peptides of species without prismatic enamel did not show similar secondary structural changes in the presence of liposomes. Peptides of mammals with prismatic enamel caused liposome leakage and inhibited LS8 and ALC cell spreading regulated by full-length Ambn. RT-PCR showed that AH is involved in Ambn's regulation of cell polarization genes: Vangl2 , Vangl1 , Prickle1 , ROCK1 , ROCK2, and Par3. Our comprehensive sequence analysis clearly demonstrates that AH motif is closely related to the emergence of enamel prismatic structure, providing insight into the evolution of complex enamel microstructure. We speculate that the AH motif evolved in mammals to interact with cell membrane, triggering signaling pathways required for specific changes in cell morphology associated with the formation of enamel prismatic structure. [ABSTRACT FROM AUTHOR]