Search results for "Molar"
showing 10 items of 1069 documents
Prevalencia de alteraciones en el patrón del sistema de conductos radiculares de los molares mandibulares
2018
La Endodoncia engloba la descripción del órgano pulpar y sus estructuras adyacentes en un estado de salud y normalidad, y el estudio de las enfermedades que les aquejan. Estos con el propósito de eliminar los factores etiológicos causantes del daño pulpar, para conseguir un ambiente dentro del sistema de conductos que permita la curación de los tejidos de soporte y garantice su salud en el largo plazo. Entre las principales razones del fracaso endodóntico encontramos la presencia de conductos sin tratar debido a no haber sido localizados y limpiados adecuadamente. Por esto es fundamental un conocimiento exhaustivo de la morfología del sistema de conductos y las posibles alteraciones que pue…
The Relationship Between Tooth Size Discrepancy and Archform Classification in Orthodontic Patients
2015
Background: To determine the relationship between clinically significant tooth size discrepancies (TSD) and archform classification in orthodontic patients. Material and Methods: Two hundred and forty consecutive sets of pre-treatment orthodontic study models were scanned and landmarked. All models had permanent teeth erupted from first molar to first molar in both arches. Sixty sets of images were classified into two groups of 30 according to the presence (group 1) or absence (group 2) of a clinically significant overall or anterior TSD (>2 SD from Bolton’s original means). Mean upper and lower archforms were created for each group using a fourth degree polynomial curve. Upper and lower ar…
Risk Factors Associated with Carious Lesions in Permanent First Molars in Children: A Seven-Year Retrospective Cohort Study
2020
The aim of this study was to evaluate the risk factors associated with the occurrence of caries in permanent teeth (PT) and in the permanent first molar (PFM) seven years after their eruption. Children born in 2005 who were enrolled in a Community Dental Program were included. A total of 278 children were enrolled. Evaluated risk factors were parental caries experience, educational level of the mother, routine medications, systemic diseases, dietary habits, toothbrushing frequency, existence of molar incisor hypomineralization (MIH) in the PT, and caries in the temporary teeth (TT). Associations between independent variables and the DMF-T (decayed, missing, and filled teeth in PT) and DMF-M…
Anionic Copolymerization Enables the Scalable Synthesis of Alternating (AB)n Multiblock Copolymers with High Molecular Weight in n/2 Steps
2018
Based on the highly disparate reactivities of isoprene (I, rI = 25.4) and 4-methylstyrene (4MS, r4MS = 0.007) in the anionic copolymerization in nonpolar media, a general strategy for the rapid and scalable synthesis of tapered multiblock copolymers with an extremely steep gradient has been developed. A repetitive addition strategy of a mixture of isoprene and 4MS leads to a tapered diblock in each case, giving access to linear alternating multiblock copolymers of the (AB)n type with up to 10 blocks. All multiblock copolymers showed narrow molecular weight distributions (dispersity Đ = 1.04–1.12). High molecular weights in the range of 80 to 400 kg mol–1 were achieved. Due to the incompatib…
Quantitative structural analysis of trabecular alveolar bone in the mandible by multidetector computed tomography: Differences according to tooth pre…
2019
Background and objective: There is a lack of quantitative measures of the quality of alveolar trabecular bone, an important factor in implantology. This study aimed to develop a method of objectively assessing the quality of trabecular bone by means of image processing and structural analysis of multidetector computed tomography images and to establish differences between tooth types and tooth presence/absence. Materials and methods: We analyzed 20 patients who underwent multidetector computed tomography to evaluate mandibular bone and tooth positioning. Image analysis included automatic segmentation of the mandible, obtainment of sections perpendicular to the dental arch, and structural an…
Use of the Transglutaminase Reaction To Study the Dissociation of Histone N-Terminal Tails from DNA in Nucleosome Core Particles
1997
We have recently shown that core histones are glutaminyl substrates for transglutaminase (TGase) and that when native nucleosome cores are incubated with monodansylcadaverine (DNC) as donor amine, this fluorescent probe is incorporated into Gln5 and Gln19 of H3 and in Gln22 of H2B [Ballestar et al. (1996) J. Biol. Chem. 271, 18817-18825]. In the present paper, we report that the cause by which Gln22 of H2B is modified in nucleosomes but not in the free histone is the interaction of the region containing that glutamine with DNA. We have used the specificity of the TGase reaction to study the changes induced by increasing ionic strength in the interaction between the histone N-terminal tails …
Synthesis and structural characterization of titanium complexes containing a sulfinyl-bridged bis(phenolato) ligand
1998
Abstract Titanium complexes containing the novel tridentate 2,2′-sulfinylbis(6-tert-butyl-4-methylphenoxo) ligand (sibmp) were synthesized and characterized. Treatment of titanium tetra-iso-propoxide with 2,2′-sulfinylbis(6-tert-4-methylphenol) (sibmpH2) in 1:1 molar ratio afforded red-orange, sparingly soluble di-iso-propoxo derivative [Ti(sibmp)(O-i-Pr)2]2·0.5 Et2O. The single-crystal structure analysis was performed and revealed a dimeric centrosymmetric structure with a planar Ti2O2 core. The titanium center is approximately octahedral with a SO function intramolecularly coordinated at the titanium center. Treatment of sibmpH2 with titanium tetra-iso-propoxide in 2:1 molar ratio gave y…
Divergent route to the preparation of hybrid Pt–Fe 2,4,6-Tris(4-ethynyl)phenyl-1,3,5-triazine metallodendrimers for nonlinear optics
2013
Abstract: The synthesis strategy for the preparation of novel platinum acetylide homometallic and heterobimetallic dendrimers (containing Fe as the other metal fragment) based on a 2,4,6-tris(4-ethynyl)phenyl-1,3,5-triazine core (3) is reported. All the dendrimer generations (G0G2) were synthesized under copper-free conditions following a divergent route. The G0-Pt dendrimer (4) was synthesized using the 1,3,5-triazine core (3) and cis-[Pt(PEt3)2Cl2] with a molar ratio of 1/4. The advantage of the current method is that different dendrimers can be prepared by following the same procedure with only changes in the molar ratios of the reactants involved. For instance, when 3 reacts with 4 in a…
Estudio anatómico del tercer molar mandibular incluido
2015
Los terceros molares son los últimos dientes en erupcionar, debido a ello no encuentran suficiente espacio para establecerse en el arco dentario, por lo que fácilmente pueden quedar retenidos. El diagnóstico inadecuado del tercer molar inferior incluido puede ser causa de numerosas complicaciones como infecciones odontogénicas, tumores benignos, malignos, caries dental entre otros. Por ello el objetivo de este estudio es conocer el desarrollo del tercer molar mandibular, analizar los cambios que se producen en su desarrollo y el espacio disponible para su erupción, relacionándolo con la edad, sexo y localización del tercer molar en la arcada. La población de estudio fue de 300 pacientes con…
Effect of electron beam irradiation and plastic deformation on molar mass of medical grade ultra-high molecular weight polyethylene
2010
Badano wpływ sterylizacji metodą napromieniania strumieniem elektronów oraz deformacji plastycznej (zgniatania, rys. 1) polietylenu ultrawielkocząsteczkowego (UHMW-PE), stosowanego do wytwarzania panewek endoprotez stawu biodrowego, na masę molową polimeru. Stwierdzono, że sterylizacja wpływa na utleniającą destrukcję makrocząsteczek polimeru, której stopień zależy od użytej dawki promieniowania (zmniejszenie masy molowej masowo średniej). Procesowi temu towarzyszy sieciowanie makrocząsteczek (wzrost udziału frakcji nierozpuszczalnej). Z kolei sama deformacja plastyczna wydaje się nie mieć wyraźnego wpływu na proces degradacji. Tymczasem łączne zastosowanie obydwu czynników zewnętrznych pro…