Mapping 123 million neonatal, infant and child deaths between 2000 and 2017

Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2—to end preventable child deaths by 2030—we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000–2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations

Reinforced dental glass ionomer cements: from conventional to nanocomposites

The use of nanoclays as reinforcement to create “polymer-clay nanocomposites” with properties greater than the parent constituents has been well established over the past few decades. In this study a systematic investigation of the reinforcement possibility of poly(acrylic acid) (PAA) with polymer-grade nanoclays (PGV and PGN nanoclays) to develop glass-ionomer cements (GICs) is presented. Chemical characterisations in order to understand the dispersion mechanism of nanoclays and PAA-nanoclay interactions were performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. Gel permeation chromatography (GPC) was conducted in order to measure the molecular weight of PAA used in cements. Several mechanical properties including, compressive strength (CS), diametral-tensile strength (DTS), flexural strength (FS), flexural modulus (E$_f$), and Vickers hardness (HV) of control groups (Fuji-IX and HiFi cement) and cements formed after the reinforcement of nanoclays were measured. The rheological studies were conducted with a Wilson’s oscillating rheometre to establish the working and setting times of cements after the reinforcement with nanoclays. Additionally, the wear resistance of cements was also measured by two different wear-test methodologies namely, reciprocating wear test (ball-on-flat) and Oregon Health & Sciences University (OH&SU) wear-simulator. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), environmental SEM (ESEM) and cryo-SEM studies were also performed to study the microstructure. XRD demonstrated that an interlayer space in nanoclays formed by a regular stacking of silicate layers along the [001] direction ($d_{001}$). The peaks in the diffraction pattern of PGN nanoclays at 2θ ~ 7.13° and PGV nanoclays at 2θ ~ 6.95° were attributed to the interlayer $d$-spacing. The interlayer space of PGN was expanded from 12.83 Å to 16.03 Å in PAA-PGN indicating that intercalation occurred whereas exfoliation occurred in PAA-PGV indicated by the lack of peak at $d_{001}$. XPS scans of PGV and PGN nanoclays depicted the main peak of O 1s photoelectron which was attributed to the various oxygen containing species such as Si-O-M (M: Mg, Al, Fe, etc) within the two layers of the silicate plate, while, Si-O-Al linkages were identified by Si 2p or Si 2s and Al 2p or Al 2s peaks. The disappearance of the Na peak in PAA-nanoclays in wide-angle XPS scans confirmed that PAA molecules exchanged sodium ions on the surface of silicate layers of nanoclays. It is suggested, that the removal of the cations from the interlayer galleries of nanoclays by the PAA chains reduced significantly the electrostatic Van-der-Waals forces between the silicate plates resulting in intercalation or exfoliation. FTIR spectra demonstrated the presence of a new peak at 1019 cm$^{−1}$ in PAA-nanoclay suspensions and the absorbance intensity of the peak at 1019 cm$^{−1}$ associated with Si-O- stretching vibrations increased with increasing nanoclays loading. The shift of the peak at 973 cm$^{−1}$, associated with Si-O- stretching vibrations in nanoclays, to 1019 cm$^{−1}$ in PAA-nanoclay and to 1041 cm$^{−1}$ in HiFi-nanoclay suspensions may be associated to the change of the chemical environment in the PAA- nanoclay suspensions. The setting reaction of GICs involves the neutralisation of PAA by the glass powder, which was linked with the formation of calcium and aluminium salt-complexes. The real-time study of the setting reaction of GICs over a period of one hour before and after nanoclays dispersion in Fuji-IX system and HiFi system presented slight differences in the FTIR spectra. The working and setting times of GICs determined by the Wilson’s rheometre exhibited a small decrease both in working and setting times of GICs prepared with the polymer liquids formed after the nanoclays dispersion, when compared to control groups (CPA-HP and CF-IX). Moreover, the mechanical properties (CS, DTS, FS, E$_f$ and HV) of GICs were determined at various aging times 1 hour, 1 day, 1 week and 1 month of storage in distilled water. Generally, GICs formed with modified PAA liquid that contained less than 2 wt % nanoclays, exhibited slightly higher CS (range 124.0– 142.0 MPa), similar DTS (range 12.0–20.0 MPa) and higher biaxial flexural strength (range 37.0–42.0 MPa) compared to the control cement groups (Fuji-IX and HiFi). E$_f$ of GICs ranged between 8.0 to 14.5 GPa and the highest values of modulus were obtained for 1 wt % nanoclay reinforcement in the HiFi GIC system. HV of cements was calculated between 62-89 HV. However, the effect of nanoclays reinforcement on various mechanical properties was not statistically significant. The ball-on-flat wear test and the OH&SU wear simulation studies suggested that the determination of the wear volume is more reliable than the wear depth. A comparison between Fuji-IX and HiFi reflected that the HiFi system always showed better wear-resistance than the Fuji- IX. It is proposed, that the improved wear resistance of the HiFi system after the dispersion of nanoclays may be due to a better methodology employed for nanoclay dispersion. However, no significant difference was observed in wear volume for different wt % nanoclays loading. TEM micrographs indicated the microstructure of PAA matrix and glass particles as well as their interaction with dispersed nanoclays. The micro-structure of porous glass particles and the presence of siliceous hydrogel phases surrounding the remnant glass core were identified. In PAA matrix, the association of porous glass particles with the nanoclays was also observed

Implant biomechanics relating to the dental implant and prosthesis design: In-vitro strain gauge analysis and finite element analysis

Background: Biomechanics of an implant-supported prosthesis play a key role in the success or failure of rehabilitation of missing teeth. This study aimed to analyze biomechanical factors, such as an implant design and prosthesis design for a single implant-supported prosthesis. An in-vitro strain gauge analysis and finite element analysis were performed to assess different implant thread shapes and prosthesis retention modes for their strain-producing property in the peri-implant region of bone. Methodology: Four study models were prepared. Two models were fitted with Bio Horizon Tapered-Pro implants having predominant buttress-shaped threads (BT) and then two models were fitted with Grande Morse Neo Dent implants having trapezoid-shaped threads (TT). Each design was used with two types of retention modes for prostheses, BP-C and TT-C for cement-retained prostheses and similarly BT-S and TT-S for screw-retained prostheses. The strain gauges were bonded to the models and connected to a strain meter. Using an opposing porcelain fused to a metal prosthesis, a combined (axial and non-axial) load of 50–300 N at a strain rate of 0.95 mm/s was applied stepwise to each prosthesis. The strain values were recorded, and the collected data were organized and analyzed using SPSS version 22. For the finite element analysis, four 3-D models were designed. The bone, dental implants, and prostheses for each group were designed using Solid Works. A static, linear simulation was conducted in Ansys software. Results and discussion: The strain values recorded were all less than 3000μɛ and within the physiological loading zone as per Frost’s theory. Statistically significant differences were found between all groups with p-values <0.05, suggesting that changes in implant design led to differences in peri-implant bone strains. At the maximum loading of 300 N, i.e., at the mean biting force of an individual adult, the maximum strain value of 1812 με was recorded for group TT-C. At the minimum loading, all strain values were less than 500 με except for group TT-C for which 518 με was recorded. The peri-implant bone next to the implant’s crest showed maximum strain, which means that this site is more subjected to the effects of overloading than any other part. The von Mises stress was seen concentrated at the implant neck. Conclusion: TT-C implant-supported prostheses give a high strain profile. In comparison, the BT-C implant-supported prostheses give a low strain profile at mean biting forces

Dental and Oral Manifestations of COVID-19 Related Mucormycosis: Diagnoses, Management Strategies and Outcomes

It has been nearly two years since the pandemic caused by the novel coronavirus disease (COVID-19) has affected the world. Several innovations and discoveries related to COVID-19 are surfacing every day and new problems associated with the COVID-19 virus are also coming to light. A similar situation is with the emergence of deep invasive fungal infections associated with severe acute respiratory syndrome 2 (SARS-CoV-2). Recent literature reported the cases of pulmonary and rhino-cerebral fungal infections appearing in patients previously infected by COVID-19. Histopathological analysis of these cases has shown that most of such infections are diagnosed as mucormycosis or aspergillosis. Rhino-orbital-cerebral mucormycosis usually affects the maxillary sinus with involvement of maxillary teeth, orbits, and ethmoidal sinuses. Diabetes mellitus is an independent risk factor for both COVID-19 as well as mucormycosis. At this point, there is scanty data on the subject and most of the published literature comprises of either case reports or case series with no long-term data available. The aim of this review paper is to present the characteristics of COVID-19 related mucormycosis and associated clinical features, outcome, diagnostic and management strategies. A prompt diagnosis and aggressive treatment planning can surely benefit these patients

Mechanical Properties of the Modified Denture Base Materials and Polymerization Methods: A Systematic Review

Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical properties are vital for the clinical longevity of the denture base. This systematic review aimed to explore the effect of newer denture base materials and/or polymerization methods on the mechanical properties of the denture base. An electronic database search of English peer-reviewed published papers was conducted using related keywords from 1 January 2011, up until 31 December 2021. This systematic review was based on guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search identified 579 papers. However, the inclusion criteria recognized 22 papers for eligibility. The risk of bias was moderate in all studies except in two where it was observed as low. Heat cure polymethyl methacrylate (PMMA) and compression moulding using a water bath is still a widely used base material and polymerization technique, respectively. However, chemically modified PMMA using monomers, oligomers, copolymers and cross-linking agents may have a promising result. Although chemically modified PMMA resin might enhance the mechanical properties of denture base material, no clear inferences can be drawn about the superiority of any polymerization method other than the conventional compression moulding technique

Biomimetic Aspects of Restorative Dentistry Biomaterials

Biomimetic has emerged as a multi-disciplinary science in several biomedical subjects in recent decades, including biomaterials and dentistry. In restorative dentistry, biomimetic approaches have been applied for a range of applications, such as restoring tooth defects using bioinspired peptides to achieve remineralization, bioactive and biomimetic biomaterials, and tissue engineering for regeneration. Advancements in the modern adhesive restorative materials, understanding of biomaterial&ndash;tissue interaction at the nano and microscale further enhanced the restorative materials&rsquo; properties (such as color, morphology, and strength) to mimic natural teeth. In addition, the tissue-engineering approaches resulted in regeneration of lost or damaged dental tissues mimicking their natural counterpart. The aim of the present article is to review various biomimetic approaches used to replace lost or damaged dental tissues using restorative biomaterials and tissue-engineering techniques. In addition, tooth structure, and various biomimetic properties of dental restorative materials and tissue-engineering scaffold materials, are discussed

Impact of acidic beverages on composition and surface characteristics of human teeth: scanning electron microscopic, stereomicroscopic and energy dispersive x-ray analyses

Abstract Objectives The objective of this study was to evaluate the effect of acidic beverages on the surface topography and elemental composition of human teeth. Methods A total of five highly acidic beverages (Red Bull, Pepsi, Apple Cidra, Tang Mosambi, and Tang Orange) were investigated. The tooth specimens of experimental groups were submerged in each beverage and incubated at 37 °C for 7 days, whereas, the tooth specimens of control groups were placed in distilled water. Afterwards, tooth specimens were analyzed using scanning electron microscopic (SEM), stereomicroscopic, and energy dispersive x-ray (EDX) techniques. Results All experimental groups revealed a decline in the tooth elements compared to controls, however, such decline was not statistically significant. Nevertheless, comparing the experimental groups, the Red Bull beverage caused a marked reduction in the percentage of both calcium and phosphorus elements compared to the Pepsi, Apple Cidra, Tang Mosambi, and Tang Orange beverages but it was insignificant as well in contrast to its control counterpart. All five acidic beverages demonstrated erosive potential under SEM analysis; however, each group of specimens showed a diverse amount of demineralization. In addition, all experimental groups exhibited significant discoloration of tooth specimens compared to their respective control counterparts. Conclusions Within the limitations of study, all five acidic beverages demonstrated erosive potential in the simulated in vitro conditions under SEM analysis; however, each group of specimens exhibited a different extent of demineralization. In addition, the overall effect of all beverages was insignificant under EDX analysis as no substantial difference was revealed between the elemental composition of experimental and control group specimens

Biological and Physicochemical Characterization of Self-Adhesive Protective Coating Dental Restorative Material after Incorporation of Antibacterial Nanoparticles

This study evaluated the physicochemical and antibacterial properties of EQUIATM coat liquid (E) after incorporation of zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles. ZnO and TiO2 (1 wt.% and 2 wt.%) were dispersed in EQUIA coat. Principal component analysis (PCA) and cluster analysis were performed to visualize systemic variation. Antibacterial activity was evaluated by colony-forming units and crystal violet staining using Streptococcusmutans and Lactobacillusacidophilus after 24 h, 48 h, and 72 h, and the microstructure was studied by scanning electron microscopy. The weight change was analyzed at 1 and 21 days. The PCA for TiO2- and ZnO-based groups showed 100% variance at all spectral ranges at 600&ndash;800/cm and 800&ndash;1200/cm, whereas 1200&ndash;1800/cm and 2700&ndash;3800/cm spectral regions demonstrated 99% variance. The absorbance values were significant (p &lt; 0.05) for both nanoparticles-based adhesives, and the specimens with 2 wt.% ZnO showed the maximum response by minimum bacterial attachment, and the control group showed the least response by maximum attachment. The weight change percentage was reduced after the incorporation of antibacterial nanoparticles. It is suggested that EQUIATM coat containing nanoparticles exhibits promising results, and it may be recommended to clinically use as an improved coating material

Structural, Physical, and Mechanical Analysis of ZnO and TiO₂ Nanoparticle-Reinforced Self-Adhesive Coating Restorative Material

This study aimed to modify an EQUIA coat (EC; GC, Japan) by incorporating 1 and 2 wt.% of zinc oxide (ZnO; EC-Z1 and EC-Z2) and titanium dioxide (TiO2; EC-T1 and EC-T2) nanoparticles, whereby structural and phase analyses were assessed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), respectively. Thermogravimetric analysis/differential scanning calorimetry, micro-hardness, and water absorption analyses were conducted, and the microstructure was studied by scanning electron microscopy/energy-dispersive spectroscopy. FTIR spectra showed a reduction in peak heights of amide (1521 cm−1) and carbonyl (1716 cm−1) groups. XRD showed peaks of ZnO (2θ ~ 31.3°, 34.0°, 35.8°, 47.1°, 56.2°, 62.5°, 67.6°, and 68.7°) and TiO2 (2θ ~ 25.3°, 37.8°, 47.9, 54.5°, 62.8°, 69.5°, and 75.1°) corresponding to a hexagonal phase with a wurtzite structure and an anatase phase, respectively. Thermal stability was improved in newly modified materials in comparison to the control group. The sequence of obtained glass transitions was EC-T2 (111 °C), EC-T1 (102 °C), EC-Z2 (98 °C), EC-Z1 (92 °C), and EC-C (90 °C). EC-T2 and EC-T1 showed the highest (43.76 ± 2.78) and lowest (29.58 ± 3.2) micro-hardness values. EC showed the maximum water absorption (1.6%) at day 7 followed by EC-T1 (0.82%) and EC-Z1 (0.61%). These results suggest that EC with ZnO and TiO2 nanoparticles has the potential to be used clinically as a coating material