983 resultados para Molar-incisor hypomineralization
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Stable isotope (SI) ratios of carbon (d13C) and nitrogen (d15N) were measured in omnivorous and carnivorous deep-sea copepods of the families Euchaetidae and Aetideidae across the Atlantic sector of the Southern Ocean to establish their trophic positions. Due to high and variable C/N ratios related to differences in lipid content, d13C was corrected using a lipid-normalisation model. d15N signals ranged from 3.0-6.9 per mil in mesopelagic species to 7.0-9.5 per mil in bathypelagic congeners. Among the carnivorous Paraeuchaeta species, the epi- to mesopelagic species Paraeuchaeta antarctica had lower d15N values than the mesopelagic P. rasa and bathypelagic P. barbata. The same trend was observed among omnivorous Aetideidae, but was not significant. In the most abundant species P. antarctica, individuals from the western Atlantic had higher d13C and d15N values than specimens at the eastern stations. These longitudinal changes in d13C and d15N values were attributed to regional differences in hydrography and sea surface temperature (SST), in particular related to a northward extension of the Antarctic Polar Front (APF) at the easternmost stations. The results indicate that even in a mesopelagic carnivorous species, the changes in surface stable isotope signatures are pronounced.
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© 2016 Springer Science+Business Media New YorkResearchers studying mammalian dentitions from functional and adaptive perspectives increasingly have moved towards using dental topography measures that can be estimated from 3D surface scans, which do not require identification of specific homologous landmarks. Here we present molaR, a new R package designed to assist researchers in calculating four commonly used topographic measures: Dirichlet Normal Energy (DNE), Relief Index (RFI), Orientation Patch Count (OPC), and Orientation Patch Count Rotated (OPCR) from surface scans of teeth, enabling a unified application of these informative new metrics. In addition to providing topographic measuring tools, molaR has complimentary plotting functions enabling highly customizable visualization of results. This article gives a detailed description of the DNE measure, walks researchers through installing, operating, and troubleshooting molaR and its functions, and gives an example of a simple comparison that measured teeth of the primates Alouatta and Pithecia in molaR and other available software packages. molaR is a free and open source software extension, which can be found at the doi:10.13140/RG.2.1.3563.4961(molaR v. 2.0) as well as on the Internet repository CRAN, which stores R packages.
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AIMS: (1) To determine if anaesthetic agent bupivacaine, has a prolonged effect on the period of acute postoperative pain when compared to lidocaine, a shorter acting agent. (2) To determine patient’s post-operative satisfaction and preference with regard to anaesthetic choice. METHODS: This double blind, randomised, interventional clinical trial included 85 patients. All patients had bilateral impacted lower third molars of removed under general anaesthetic. All patients received 0.5% plain bupivacaine on one randomly allocated side, with 2% lidocaine (with adrenaline) administered on the opposite side. Pain was measured using visual analogue scales at 0, 30, 60 minutes and 3, 4, 6 and 8 hours post-surgery. Pain was analysed for 1 week following surgery. Psychological evaluations and patient reported outcomes, including patient satisfaction were evaluated. RESULTS: A significant difference in pain (P=0.001) was seen during the 3-8 hour post-operative period. The upper limit of the 95% confidence interval was 10.0 or above at 3hours and 4 hours post-surgery. Two-thirds of patients preferred bupivacaine. CONCLUSION: Longer lasting anaesthetics such as bupivacaine offer a longer period of analgesia, and improve overall patient satisfaction.
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Chitosan is a polysaccharide derived from chitin, mainly of crustacean shells and shrimp wastes. The utilization of chitosan is related to the molar weight and deacetylation degree of the biopolymer. The aim of this work is to study the chitin deacetylation reaction, by the viscosity average molar weight and deacetylation degree of chitosan as a function of reaction time. Deacetylation was carried out in concentrated alkaline solution, 421 g L−1, at 130◦C and the reaction occurred during 4 h. Chitosan paste obtained after 20, 90 and 240 min was used to produce biofilms, which were characterized according water vapor permeability and mechanical properties (tensile strength and percentage tensile elongation at break). During the reaction time deacetylation degree reached 93%, and a 50% reduction in the viscosity average molar weight value in relation to the value of the first 20 min of reaction was found Both reactions presented a kinetic behavior of the pseudo-first order. Biofilm produced from the paste of chitosan with high deacetylation degree showed higher water vapor permeability (WVP), tensile strength (TS) and elongation (E) when compared to films with a low deacetylation.
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In this study, the partial molar volumes of L-serine and L-threonine in aqueous solutions of ammonium sulfate at (0.0, 0.1, 0.3, 0.7, and 1.0) mol.kg(-1) are reported between 278.15 and 308.15 K. Transfer volumes and hydration numbers were obtained, which are larger in L-serine than in L-threonine. Dehydration of the amino acids is observed, rising with the temperature and salt molality. The data suggest that interactions between ions and charged/hydrophilic groups are predominant, and by applying the McMillan and Mayer formalism, it was concluded that they are mainly pair wise. The combination of the data presented in this study with solubility and molecular dynamics data suggests a stronger interaction of the ammonium cation with the zwitterionic centers of the amino acids when compared to the interactions of those centers with the sulfate anion.
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In this work, the partial molar volumes of glycine and DL-alanine in aqueous solutions of ammonium sulfate at 0.0, 0.1, 0.3, 0.7, and 1.0 mol.kg(-1) are determined between 278.15 and 308.15 K. Transfer volumes were obtained, which are larger for glycine than DL-alanine. On the contrary, the hydration numbers are higher for DL-alanine than glycine, and dehydration of the amino acids is observed with increasing temperature or salt molality. The data suggest that interactions between ion and charged/hydrophilic groups are predominant and, by applying the methodology proposed by Friedman and Krishnan, it was concluded that they are mainly pairwise. A group-contribution scheme has been successfully applied to the pairwise volumetric interaction coefficient. Finally, the dehydration effect on glycine, alanine and serine in the presence of different electrolytes has been rationalized in terms of the charge density and a parameter accounting for the cation's hydration.
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La impactación de terceros molares en la región condilar es muy inusual. Este artículo describe el caso de cordal incluido en región subcondilar en una mujer que refirió dolor inespecífico hemifacial y varios episodios de tumefacción. Se describe el manejo quirúrgico de estas inclusiones y se realiza una revisión bibliográfica.
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Aim: This prospective cohort study was to evaluate the independent and mutual effects of socioeconomic, oral health behaviors and individual clinical factors, including enamel hypomineralization, as possible risk factors for increase in caries experience in second primary molar (SPM) over a period of 2-years. Methods: Children (n=216) aged 4-6 years were examined for hypomineralized second primary molar (HSPM) and dental caries in school settings and were recalled every 6 months. The caregivers filled out a semi-structured questionnaire about their socio-demographic and oral health-related behaviors. Data analysis was performed using a hierarchical model with three levels. Multiple analyses were performed at each level and variables with p<0.20 were tested by stepwise multiple Generalized Estimating Equation. Results: At final examination, 33.3% of the children had developed new caries lesions in SPM. The model showed that the number of years of mother’s schooling and the caregiver´s perception about their children’s caries experience played a protective role in the incidence of dental caries. Children who had white spot lesions were more likely to develop new carious lesions in SPM. Children with HSPM showed no higher incidence of caries in their SPM than those without HSPM. Conclusions: Clinical, socioeconomic and behavioral factors impacted on caries development in primary second molars. However, further studies are required to better understand the role of HSPM in caries development in other age groups.
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Aim: To investigate the effect of implant-abutment angulation and crown material on stress distribution of central incisors. Finite element method was used to simulate the clinical situation of a maxillary right central incisor restored by two different implant-abutment angulations, 15° and 25°, using two different crown materials (IPS E-Max CAD and zirconia). Methods: Two 3D finite element models were specially prepared for this research simulating the abutment angulations. Commercial engineering CAD/CAM package was used to model crown, implant abutment complex and bone (cortical and spongy) in 3D. Linear static analysis was performed by applying a 178 N oblique load. The obtained results were compared with former experimental results. Results: Implant Von Mises stress level was negligibly changed with increasing abutment angulation. The abutment with higher angulation is mechanically weaker and expected to fail at lower loading in comparison with the steeper one. Similarly, screw used with abutment angulation of 25° will fail at lower (about one-third) load value the failure load of similar screw used with abutment angulated by 15°. Conclusions: Bone (cortical and spongy) is insensitive to crown material. Increasing abutment angulation from 15° to 25°, increases stress on cortical bone by about 20% and reduces it by about 12% on spongy bone. Crown fracture resistance is dramatically reduced by increasing abutment angulation. Zirconia crown showed better performance than E-Max one.
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Les cellules épithéliales qui produisent l’émail, les améloblastes, sont séparées de l'émail au niveau de la zone de maturation par une membrane basale spécialisée (MBS) enrichie en laminine 332 (LM-332). Cette protéine hétérotrimérique (composée des chaînes α3, ß3 et γ2) assure l'intégrité structurelle des membranes basales (MB) et influence divers processus cellulaires épithéliaux tels que l'adhésion et la différenciation cellulaire. Des modèles de souris « knockout » (KO), où les gènes codant pour LM-332 ont été supprimés, meurent peu après la naissance. Néanmoins, ce phénotype létal peut être contourné en substituant chez la souris le gène produisant la chaîne γ2 de la laminine (LAMC2) par sa forme humaine, sous le contrôle de l’expression du promoteur-rtTA, de la cytokératine 14, inductible par la prise de doxycycline (Dox) - (Tet-on). Le but de ce projet est d’examiner si l’utilisation de cette protéine humaine chez la souris a un effet sur la structuration de la MBS ainsi que sur la maturation de l'émail. La phase de maturation de l’organe de l’émail chez la souris transgénique a été sévèrement altérée par rapport à une souris normale (WT). La MBS n’est plus visible, une matrice dystrophique s’est formée dans la couche d'émail dans la phase de maturation, et la présence d’une matrice résiduelle de l'émail est observée durant la phase tardive de maturation. Des micro-analyses tomographiques ont révélé une usure excessive des surfaces occlusales des molaires, un écroulement de l'émail sur les pointes des incisives et une hypominéralisation de l'émail. Cependant, aucune altération structurale due à cette recombinaison transgénique n’a été observée dans d'autres sites épithéliaux, tels que la peau, le palais et la langue. Ces résultats indiquent que, bien que ce modèle de souris humanisée soit capable de rétablir ses fonctions dans divers tissus épithéliaux, il est incapable de soutenir la structuration d'une MBS à l'interface entre les améloblastes et l’émail en maturation. Cet échec peut être lié à la composition spécifique de la MBS dans la phase de maturation et supporte l’hypothèse que la MBS est essentielle pour la maturation adéquate de l'émail.
Resumo:
Les cellules épithéliales qui produisent l’émail, les améloblastes, sont séparées de l'émail au niveau de la zone de maturation par une membrane basale spécialisée (MBS) enrichie en laminine 332 (LM-332). Cette protéine hétérotrimérique (composée des chaînes α3, ß3 et γ2) assure l'intégrité structurelle des membranes basales (MB) et influence divers processus cellulaires épithéliaux tels que l'adhésion et la différenciation cellulaire. Des modèles de souris « knockout » (KO), où les gènes codant pour LM-332 ont été supprimés, meurent peu après la naissance. Néanmoins, ce phénotype létal peut être contourné en substituant chez la souris le gène produisant la chaîne γ2 de la laminine (LAMC2) par sa forme humaine, sous le contrôle de l’expression du promoteur-rtTA, de la cytokératine 14, inductible par la prise de doxycycline (Dox) - (Tet-on). Le but de ce projet est d’examiner si l’utilisation de cette protéine humaine chez la souris a un effet sur la structuration de la MBS ainsi que sur la maturation de l'émail. La phase de maturation de l’organe de l’émail chez la souris transgénique a été sévèrement altérée par rapport à une souris normale (WT). La MBS n’est plus visible, une matrice dystrophique s’est formée dans la couche d'émail dans la phase de maturation, et la présence d’une matrice résiduelle de l'émail est observée durant la phase tardive de maturation. Des micro-analyses tomographiques ont révélé une usure excessive des surfaces occlusales des molaires, un écroulement de l'émail sur les pointes des incisives et une hypominéralisation de l'émail. Cependant, aucune altération structurale due à cette recombinaison transgénique n’a été observée dans d'autres sites épithéliaux, tels que la peau, le palais et la langue. Ces résultats indiquent que, bien que ce modèle de souris humanisée soit capable de rétablir ses fonctions dans divers tissus épithéliaux, il est incapable de soutenir la structuration d'une MBS à l'interface entre les améloblastes et l’émail en maturation. Cet échec peut être lié à la composition spécifique de la MBS dans la phase de maturation et supporte l’hypothèse que la MBS est essentielle pour la maturation adéquate de l'émail.
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The tridecameric Al-polymer [AlO4Al12(OH)24(H2O)12]7+ was prepared by forced hydrolysis of Al3+ up to an OH/Al molar ratio of 2.2. Under slow evaporation crystals were formed of Al13-nitrate. Upon addition of sulfate the tridecamer crystallised as the monoclinic Al13-sulfate. These crystals have been studied using near-infrared spectroscopy and compared to Al2(SO4)3.16H2O. Although the near-infrared spectra of the Al13-sulfate and nitrate are very similar indicating similar crystal structures, there are minor differences related to the strength with which the crystal water molecules are bonded to the salt groups. The interaction between crystal water and nitrate is stronger than with the sulfate as reflected by the shift of the crystal water band positions from 6213, 4874 and 4553 cm–1 for the Al13 sulfate towards 5925, 4848 and 4532 cm–1 for the nitrate. A reversed shift from 5079 and 5037 cm–1 for the sulfate towards 5238 and 5040 cm–1 for the nitrate for the water molecules in the Al13 indicate that the nitrate-Al13 bond is weakened due to the influence of the crystal water on the nitrate. The Al-OH bond in the Al13 complex is not influenced by changing the salt group due to the shielding by the water molecules of the Al13 complex.
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Infrared spectroscopy has been used to study nano to micro sized gallium oxyhydroxide α-GaO(OH), prepared using a low temperature hydrothermal route. Rod-like α-GaO(OH) crystals with average length of ~2.5 μm and width of 1.5 μm were prepared when the initial molar ratio of Ga to OH was 1:3. β-Ga2O3 nano and micro-rods were prepared through the calcination of α-GaO(OH) The initial morphology of α-GaO(OH) is retained in the β-Ga2O3 nanorods. The combination of infrared and infrared emission spectroscopy complimented with dynamic thermal analysis were used to characterise the α-GaO(OH) nanotubes and the formation of β-Ga2O3 nanorods. Bands at around 2903 and 2836 cm-1 are assigned to the -OH stretching vibration of α-GaO(OH) nanorods. Infrared bands at around 952 and 1026 cm-1 are assigned to the Ga-OH deformation modes of α-GaO(OH). A significant number of bands are observed in the 620 to 725 cm-1 region and are assigned to GaO stretching vibrations.