Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 205
Filtrar
1.
Philos Trans R Soc Lond B Biol Sci ; 375(1810): 20190513, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-32892733

RESUMO

During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO2) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO2 seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO2 gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO2 cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO2 due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO2 transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO2 uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO2 anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO2 anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.


Assuntos
Atmosfera/análise , Ciclo do Carbono , Dióxido de Carbono/análise , Secas , Ecossistema , Europa (Continente)
2.
Nat Commun ; 10(1): 2728, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227698

RESUMO

The development of useful structure-function relationships for materials that exhibit correlated nanoscale disorder requires adequately large atomistic models which today are obtained mainly via theoretical simulations. Here, we exploit our recent advances in structure-refinement methodology to demonstrate how such models can be derived directly from simultaneous fitting of 3D diffuse- and total-scattering data, and we use this approach to elucidate the complex nanoscale atomic correlations in the classical relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN). Our results uncover details of ordering of Mg and Nb and reveal a hierarchical structure of polar nanoregions associated with the Pb and Nb displacements. The magnitudes of these displacements and their alignment vary smoothly across the nanoregion boundaries. No spatial correlations were found between the chemical ordering and the polar nanoregions. This work highlights a broadly applicable nanoscale structure-refinement method and provides insights into the structure of PMN that require rethinking its existing contentious models.

3.
Sci Rep ; 7(1): 15620, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29142205

RESUMO

Perovskite potassium sodium niobates, K1-xNaxNbO3, are promising lead-free piezoelectrics. Their dielectric and piezoelectric characteristics peak near x = 0.5, but the reasons for such property enhancement remain unclear. We addressed this uncertainty by analyzing changes in the local and average structures across the x = 0.5 composition, which have been determined using simultaneous Reverse Monte Carlo fitting of neutron and X-ray total-scattering data, potassium EXAFS, and diffuse-scattering patterns in electron diffraction. Within the A-sites, Na cations are found to be strongly off-centered along the polar axis as a result of oversized cube-octahedral cages determined by the larger K ions. These Na displacements promote off-centering of the neighboring Nb ions, so that the Curie temperature and spontaneous polarization remain largely unchanged with increasing x, despite the shrinking octahedral volumes. The enhancement of the properties near x = 0.5 is attributed to an abrupt increase in the magnitude and probability of the short-range ordered octahedral rotations, which resembles the pre-transition behavior. These rotations reduce the bond tension around Na and effectively soften the short Na-O bond along the polar axis - an effect that is proposed to facilitate reorientation of the polarization as external electric field is applied.

4.
Disabil Health J ; 9(3): 354-74, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26962020

RESUMO

BACKGROUND: Negative attitudes toward disability cause difficulties in integrating persons with disabilities (PWDs) into society and limit their access to health care, education, employment, and leisure. Being aware of societal attitudes toward disability may help explain discrimination against PWDs and draw attention to the solutions needed to address these. Good measures of attitudes are vital for this purpose. OBJECTIVE: The aim is to synthesize published information, including evidences on psychometric properties and overall utility on instruments that measure attitudes toward disability. METHODS: A two-tiered search process was performed to identify instruments that measure attitudes toward disability and retrieve articles that describe their development and/or validation. The CanChild Outcome Measures Rating Form was utilized to determine the overall utility of the instruments. Results were synthesized using a self-constructed data extraction form. RESULTS: Thirty-one instruments were included in the study. Five measured attitudes toward communication disability, 7 toward intellectual disability, 4 toward mental illness, and 15 toward disability in general. Target respondents ranged from children to adults, and included respondents from different occupations and cultural backgrounds. Twenty-three were found to have adequate overall utility, while 8 have poor overall utility. CONCLUSION: Several instruments are available in literature and all may be used for their intended purposes as long as their limitations are considered. Many still require further validation to ascertain their validity and responsiveness to change.


Assuntos
Atitude , Pessoas com Deficiência , Preconceito , Discriminação Social , Inquéritos e Questionários , Humanos , Psicometria
5.
J Obstet Gynaecol ; 35(6): 585-90, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25774537

RESUMO

We aimed to investigate whether conservative management of preterm premature rupture of membranes (PPROM) at 32-34 weeks' gestation improves outcome. In this retrospective analysis of singleton pregnancies, the study group included patients with PPROM at 28-34 weeks' gestation and the control group included patients presented with spontaneous preterm delivery at 28-34 weeks' gestation. Both groups were subdivided according to gestational age - early (28-31 weeks' gestation) versus late (32-34 weeks' gestation). Adverse neonatal outcome included neonatal death, intraventricular haemorrhage grade 3/4, respiratory distress syndrome, periventricular leucomalacia and neonatal sepsis. The study and control groups included 94 and 86 women, respectively. The study group had a lower incidence of adverse neonatal outcome at the earlier weeks (28-31), compared with the control group at the same gestational age. In contrast, at 32-34 weeks' gestation no difference in the risk for adverse neonatal outcome was noticed. Additionally, within the study group, chorioamnionitis rate was significantly higher among those who delivered at 32-34 weeks' gestation (p < 0.01). No advantage for conservative management of PPROM was demonstrated beyond 31 weeks' gestation. Moreover, conservative management of PPROM at 32-34 weeks' gestation may expose both mother and neonate to infectious morbidity.


Assuntos
Ruptura Prematura de Membranas Fetais/terapia , Idade Gestacional , Resultado da Gravidez , Resultado do Tratamento , Cesárea/estatística & dados numéricos , Corioamnionite/epidemiologia , Feminino , Ruptura Prematura de Membranas Fetais/epidemiologia , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/epidemiologia , Tempo de Internação , Gravidez , Nascimento Prematuro/epidemiologia , Estudos Retrospectivos
8.
Conserv Biol ; 27(6): 1366-77, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24033638

RESUMO

Haemosporidian parasites in the genus Plasmodium were recently detected through molecular screening in the Galapagos Penguin (Spheniscus mendiculus). We summarized results of an archipelago-wide screen of 3726 endemic birds representing 22 species for Plasmodium spp. through a combination of molecular and microscopy techniques. Three additional Plasmodium lineages were present in Galapagos. Lineage A-infected penguins, Yellow Warblers (Setophaga petechia aureola), and one Medium Ground Finch (Geospiza fortis) and was detected at multiple sites in multiple years [corrected]. The other 3 lineages were each detected at one site and at one time; apparently, they were transient infections of parasites not established on the archipelago. No gametocytes were found in blood smears of infected individuals; thus, endemic Galapagos birds may be dead-end hosts for these Plasmodium lineages. Determining when and how parasites and pathogens arrive in Galapagos is key to developing conservation strategies to prevent and mitigate the effects of introduced diseases. To assess the potential for Plasmodium parasites to arrive via migratory birds, we analyzed blood samples from 438 North American breeding Bobolinks (Dolichonyx oryzivorus), the only songbird that regularly migrates through Galapagos. Two of the ephemeral Plasmodium lineages (B and C) found in Galapagos birds matched parasite sequences from Bobolinks. Although this is not confirmation that Bobolinks are responsible for introducing these lineages, evidence points to higher potential arrival rates of avian pathogens than previously thought. Linajes Múltiples de Parásitos de Malaria Aviar (Plasmodium) en las Islas Galápagos y Evidencia de su Arribo por Medio de Aves Migratorias.


Assuntos
Migração Animal , Aves/parasitologia , Conservação dos Recursos Naturais , Plasmodium/classificação , Animais , DNA de Protozoário/química , Equador , Espécies Introduzidas , Filogenia , Plasmodium/genética , Plasmodium/isolamento & purificação
11.
Nano Lett ; 12(5): 2599-604, 2012 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-22494191

RESUMO

Test platforms for the ideal strength of materials are provided by almost defect-free nanostructures (nanowires, nanotubes, nanoparticles, for example). In this work, the ultimate bending strengths of Si nanowires with radii in the 20-60 nm range were investigated by using a new bending protocol. Nanowires simply held by adhesion on flat substrates were bent through sequential atomic force microscopy manipulations. The bending states prior to failure were analyzed in great detail to measure the bending dynamics and the ultimate fracture strength of the investigated nanowires. An increase in the fracture strengths from 12 to 18 GPa was observed as the radius of nanowires was decreased from 60 to 20 nm. The large values of the fracture strength of these nanowires, although comparable with the ideal strength of Si, are explained in terms of the surface morphology of the nanowires.

12.
BJOG ; 118(6): 741-7, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21332633

RESUMO

OBJECTIVE: The placenta weight/birthweight (PW/BW) ratio has been shown to be associated with certain long-term fetal outcomes; however, its association with short-term outcomes has not received much attention. Our aim was to assess the correlation between the PW/BW ratio and short-term adverse obstetrics outcomes in full-term, appropriate-for-gestational-age (AGA) newborns. DESIGN: Retrospective cohort study analysis using data from the McGill Obstetrical and Neonatal Database. SETTING: McGill University Health Centre in Montreal Canada. POPULATION: AGA neonates. METHODS: Three groups of full-term AGA neonates were created, according to their PW/BW ratio (high, normal and low), to be compared. Our primary outcome was the admission rate to the neonatal intensive care unit (NICU), and secondary outcomes included an Apgar score < 7 at 5 minutes, cord PH < 7.0, cord base excess (BE) ≤ 12, respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), occurrence of apnoea episodes, breech presentation at delivery, caesarean section rate and status in discharge home. A logistic regression model was instituted to investigate the predictors for adverse obstetrics outcomes. MAIN OUTCOME MEASURE: Admission to the NICU. RESULTS: Compared with the group with normal PW/BW ratios, the high PW/BW ratio group was associated with increased rates of admission to the NICU, of Apgar scores < 7 at 5 minutes, of breech presentation and caesarean section. On the contrary, the low PW/BW ratio group showed decreased rates of NICU admission, breech presentation and caesarean section. CONCLUSIONS: A high PW/BW ratio is significantly correlated with short-term adverse perinatal outcomes. This ratio may be used as a new and simple warning sign to predict the possibility of short-term health risks for newborns.


Assuntos
Peso ao Nascer/fisiologia , Placenta/anatomia & histologia , Adulto , Índice de Apgar , Apresentação Pélvica , Cesárea/estatística & dados numéricos , Cuidados Críticos/estatística & dados numéricos , Permeabilidade do Canal Arterial/etiologia , Feminino , Idade Gestacional , Humanos , Concentração de Íons de Hidrogênio , Recém-Nascido , Masculino , Tamanho do Órgão , Mortalidade Perinatal , Gravidez , Resultado da Gravidez , Síndrome do Desconforto Respiratório do Recém-Nascido/etiologia , Estudos Retrospectivos , Nascimento a Termo/fisiologia
13.
Placenta ; 32(1): 58-62, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21036395

RESUMO

OBJECTIVE: To establish updated placental percentile nomograms in a large North American population for singleton and twin gestations for the use of researchers and clinicians. STUDY DESIGN: Data was extracted from our computerized registry; McGill Obstetrics and Neonatal Database (MOND). The registry includes all the obstetrical data on all deliveries at the McGill University, including placental weight, placental pathologies, maternal and perinatal complications. 20,635 singleton deliveries and 527 twin deliveries were included. Placental weight, gestational age at delivery, birth weight and gender were retrieved. Tables and figures for the 3rd,10th,25th, 50th, 75th 90th, and 97th percentile of placental weight by gestational age, placental weight by birth weight and placental to birth weight ratio by gestational age were produced. RESULTS: Tables and figures are presented for placental percentiles curves according to gestational age, gestational weight and gender for singleton and twin deliveries. In addition, tables and figures are presented for the ratio of placental weight to birth weight. CONCLUSIONS: Population percentile curves have been produced for placental weight and for the ratio of placental weight to birth weight to for singleton and twin deliveries.


Assuntos
Placentação , Gravidez Múltipla , Estudos Transversais , Parto Obstétrico , Feminino , Desenvolvimento Fetal/fisiologia , Idade Gestacional , Gráficos de Crescimento , Humanos , Recém-Nascido , Masculino , Nomogramas , Tamanho do Órgão , Placenta/anatomia & histologia , Gravidez , Gravidez Múltipla/fisiologia , Gêmeos
14.
J Assist Reprod Genet ; 25(8): 353-7, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18704673

RESUMO

PURPOSE: To examine whether double transfer of embryos on day 2-3 and on day 5 after ovum pick-up (OPU) improves IVF/ET success rates in patients with multiple consecutive IVF failures METHODS: Consecutive IVF failures patients (7.6 +/- 0.5) undergoing IVF/ET cycles were treated with interval double transfer on day 2-3 and on day 5 after OPU. Matched patients, that had embryos transferred only once on day 2 or 3 served as controls. RESULTS: Baseline and cycle characteristics were similar in the study group and controls. The total pregnancy rate was 44.6% in the study group and 24.2% in the controls (p = 0.001), and the clinical pregnancy rates were 38.5% and 19.6%, respectively (p = 0.001). CONCLUSIONS: Patients with multiple consecutive IVF/ET failures, treated with the interval double transfer approach had significantly improved cycle success rates compared with regular day 2 or 3 embryo transfer protocol.


Assuntos
Transferência Embrionária/métodos , Fertilização in vitro/métodos , Adulto , Estudos de Casos e Controles , Implantação do Embrião , Feminino , Humanos , Modelos Estatísticos , Oócitos/citologia , Gravidez , Taxa de Gravidez , Estudos Retrospectivos , Resultado do Tratamento
15.
Gynecol Obstet Fertil ; 36(7-8): 743-7, 2008.
Artigo em Francês | MEDLINE | ID: mdl-18650116

RESUMO

OBJECTIVES: To evaluate surgical treatment for genital prolapse in patients over the age of 75. PATIENTS AND METHODS: This is a continuous retrospective series of 43 patients operated for genital prolapse between March 2001 and October 2006. Surgical outcomes in terms of anatomical correction as well as urological and proctological results were analyzed. Morbidity and mortality studies were carried out. A satisfaction and quality of life assessment was carried out among 19 patients (44%) by an independent researcher at a distance from the intervention. RESULTS: Morbidity attributable to the surgery was minimal, with no cases of mortality. Mean hospital stay was five days. Anatomical correction was good without troubling urological or proctological consequences. Two surgical options were compared: surgery with vaginal occlusion in 23 patients (53.5%) and vaginal conserving surgery in 20 patients (46.5%). Surgical outcomes and morbidity were equivalent in the two groups. Seventy-nine percent of patients surveyed at a distance from the interventions estimated that the procedure had improved their quality of life. DISCUSSION AND CONCLUSION: Surgical treatment for genital prolapse in the very elderly population is a reasonable therapeutic option. Postoperative evaluation demonstrates good anatomical as well as functional results in the majority of cases.


Assuntos
Prolapso Uterino/cirurgia , Idoso , Idoso de 80 Anos ou mais , Cirurgia Colorretal , Feminino , Humanos , Complicações Pós-Operatórias/classificação , Complicações Pós-Operatórias/mortalidade , Estudos Retrospectivos , Urologia
16.
Resuscitation ; 73(3): 400-6, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17289249

RESUMO

INTRODUCTION: Computerised physician order entry with clinical decision support system (CPOE+CDSS) is an important tool in attempting to reduce medication errors. The objective of this study was to evaluate the impact of a CPOE+CDSS on (1) the frequency of errors in ordering resuscitation (CPR) medications and (2) the time for printing out the order form, in a paediatric critical care department (PCCD). SETTING: An 18-bed PCCD in a tertiary-care children's hospital. DESIGN: Prospective cohort study. MEASURES: Compilation and comparison of number of errors and time to fill in forms before and after implementation of CPOE+CDSS. Time to fill in conventional, simulated and CPOE forms was measured and compared. RESULTS: There were three reported incidents of errors among 13,124 CPR medications orders during the year preceding implementation of CPOE+CDSS. These represent errors that escaped the triple check by three independent staff members. There were no errors after CPOE+CDSS was implemented (100% error reduction for 46,970 orders). Time to completion of drug forms dropped from 14 min 42 s to 2 min 14s (p < 0.001). CONCLUSIONS: CPOE+CDSS completely eliminated errors in filling in the forms and significantly reduced time to completing the form.


Assuntos
Reanimação Cardiopulmonar , Sistemas de Apoio a Decisões Clínicas , Sistemas de Registro de Ordens Médicas , Erros de Medicação/prevenção & controle , Inconsciência/tratamento farmacológico , Criança , Humanos , Unidades de Terapia Intensiva Pediátrica , Estudos Prospectivos , Fatores de Tempo
17.
Biopolymers ; 82(6): 615-22, 2006 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-16557500

RESUMO

Raman spectra of normal hair shafts and hair shafts from patients exhibiting trichothiodystrophy (TTD) were obtained using line focus laser illumination. Because hair from TTD patients has a significant decrease in the content of the sulfur-containing amino acids in comparison to normal hair, the 550-500 cm(-1) disulfide stretching mode region of the Raman spectrum was examined in detail. A quantitative spectral analysis demonstrates significant increases in the two energetically less favored gauche-gauche-trans (g-g-t) and trans-gauche-trans (t-g-t) forms. These observations suggest that the increased amounts of these less stable disulfide conformers are contributing factors to or associated with the hair brittleness observed for this congenital disorder. Structure-spectra correlations for the three dominant disulfide conformers are confirmed by quantum chemical calculations using modern density functional theory (DFT).


Assuntos
Doenças do Cabelo/metabolismo , Cabelo/química , Proteínas/química , Biopolímeros/química , Reparo do DNA/genética , Dissulfetos/química , Cabelo/patologia , Doenças do Cabelo/genética , Doenças do Cabelo/patologia , Humanos , Modelos Moleculares , Conformação Proteica , Análise Espectral Raman
18.
Bull Entomol Res ; 95(6): 605-13, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16336708

RESUMO

The two most widespread biotypes of Bemisia tabaci (Gennadius) in southern Europe and the Middle East are referred to as the B and Q-type, which are morphologically indistinguishable. In this study various DNA markers have been developed, applied and compared for studying genetic diversity and distribution of the two biotypes. For developing sequence characterized amplified regions (SCAR) and cleaved amplified polymorphic sequences (CAPS) techniques, single random amplified polymorphic DNA (RAPD) fragments of B and Q biotypes, respectively, were used. The CAPS were investigated on the basis of nuclear sodium channel and the mitochondrial cytochrome oxidase I genes (mtCOI) sequences. In general, complete agreement was found between the different markers used. Analysis of field samples collected in Israel for several years, using these markers, indicated that the percentage of the Q biotype tends to increase in field populations as time progresses. This may be attributed to the resistance of the Q biotype to neonicotinoids and pyriproxyfen and the susceptibility of the B biotype to these insecticides.


Assuntos
Hemípteros/genética , Animais , Genes de Insetos , Marcadores Genéticos , Genética Populacional , Hemípteros/classificação , Israel , Dinâmica Populacional , Técnica de Amplificação ao Acaso de DNA Polimórfico , Análise de Sequência de DNA
19.
J Dairy Sci ; 88(2): 569-76, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15653522

RESUMO

Albumin is a well-characterized product of the liver. In the present study, objectives were to determine if the albumin gene is also expressed in various nonhepatic tissues in the bovine; whether mammary gland epithelial cells synthesize albumin; and how its synthesis is affected by bovine mastitis. Albumin expression was monitored using reverse transcription-polymerase chain reaction. Tissues examined were: liver, mammary gland, tongue, intestine, lymph gland, testicle, ovary, and uterus. All tissues except the ovary expressed the albumin gene, albeit less so than the liver. The highest level of expression (other than liver) was found in the lymph nodes but expression was also found in the mammary gland. Incubation of mammary gland explants with the labeled amino acid L-[(35)S] methionine resulted in formation of labeled immunoprecipitable albumin, newly synthesized in the explant. Immunoprecipitable albumin in the medium verified that newly synthesized albumin was also secreted into the medium. This shows that the gland itself is a source of milk albumin. Albumin mRNA expression was approximately 4 times higher in mammary gland tissue from 6 mastitic cows compared with expression in mammary tissue from 6 healthy glands. Further, secretion of albumin was increased 3.5-fold from explants of mastitic mammary glands compared with secretion from explants of healthy mammary glands. Addition of lipopolysaccharide increased the synthesis and secretion of albumin in mammary gland cells in a dose-dependent manner. Exposure to lipopolysaccharide accelerated albumin synthesis in a time-dependent manner up to 48 h. These results lead us to suggest that the secretion of albumin by the mammary gland is part of the innate nonspecific defense system.


Assuntos
Albuminas/biossíntese , Albuminas/genética , Bovinos/metabolismo , Expressão Gênica , Glândulas Mamárias Animais/metabolismo , Albuminas/metabolismo , Animais , Feminino , Técnicas de Imunoadsorção , Intestinos/química , Lipopolissacarídeos/farmacologia , Fígado/química , Masculino , Glândulas Mamárias Animais/química , Glândulas Mamárias Animais/efeitos dos fármacos , Mastite Bovina/metabolismo , Ovário/química , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Testículo/química , Técnicas de Cultura de Tecidos , Língua/química , Útero/química
20.
Refuat Hapeh Vehashinayim (1993) ; 21(1): 54-9, 101-2, 2004 Jan.
Artigo em Hebraico | MEDLINE | ID: mdl-15065385

RESUMO

UNLABELLED: Anterior maxillary implantation is a challenging treatment for both the surgeon and prosthodontist due to high esthetic demands in this area. However, it is the most traumatized and most exposed region to habits. Prompt and appropriate management can significantly improve prognosis of many dentoalveolar injuries, especially in young patients. Unfortunately, many traumatized teeth are overtreated or left untreated, which lead to a much more complicated treatment at the time of permanent restoration at adulthood. The facial cortical plate over the roots of the maxillary teeth is thin and porous. Periapical infections, as well as prolonged and stubborn surgical treatments (repeated root end surgeries) can cause resorption of the labial plate, migrate to a more palatal position, and may later require an augmentation procedure prior to implant placement. The treatment-options of traumatized, anterior maxillary, un-restorable fractured root and ankylosed infraocluded teeth, in relation to preservation of the adjacent alveolar bone for future use of dental implantation will be discussed. The recommended treatment of crown-root fracture of permanent incisor includes removal of the coronal fragment and supragingival restoration of the fractured root. In severe cases in which the fracture line positions deeply under the gingival margin, this treatment may be supplemented by gingivectomy and/or osteotomy, as well as surgical or orthodontic extrusion of the root. In young patients, use of these treatment options as temporary treatment to preserve the facial cortical plate is important. Preservation of alveolar dimension will enable implantation after the completion of growth and development. Dento-alveolar ankylosis accompanied by replacement resorption is a serious complication following severe injury to the periodontal membrane. This complication develops mainly following avulsion and intrusion but also following lateral luxation and root fracture. Replacement resorption develops after severe damage to the periodontal ligament cells that cover the root surface. As a result of this damage, the periodontal ligament is replaced by bone tissue, causing ankylosis between bone and tooth. Following ankylosis, resorption of cementum and root dentin occurs. These processes eventually result in replacement of the entire root by bone. In young children it could arrest the growth of the alveolar process and create an infra-occluded tooth, resulting in a severe bony defect that is difficult to correct. In addition, loss of the maxillary incisor leads to serious esthetic and restorative problems, particularly when the trauma occurs at a young age. Therefore, ankylosed teeth should be treated as soon as diagnosed. Alternative treatments include intentional extraction and immediate replantation of the ankylosed tooth to its socket after embedding the tooth and the socket in Emdogain. This treatment is indicated only when the ankylosis or the replacement resorption is diagnosed at an early stage or has affected only a small area of the root. When the resorption is diagnosed at a later stage, auto transplantation of first lower pre-molar to the anterior region or decoronation of the ankylosed tooth may be considered. Decoronation is a simple and safe surgical procedure for preservation of alveolar bone prior to implant placement. It should be considered as a treatment option for teeth affected by replacement resorption. The alternative treatment of surgical extraction of an ankylosed tooth often leads to considerable bone loss and reduced bone volume in the oro-facial dimension. This may later necessitate an augmentation procedure. CONCLUSION: Scrupulous diagnosis of teeth and the alveolar bone after a traumatic injury is necessary. Treatment is multidisciplinary, requiring endodontic, surgical, orthodontic, operative and prosthetic compliance. An individual treatment plan for each patient is necessary. General rule do not apply. Periodic check-up is essential.


Assuntos
Processo Alveolar/patologia , Incisivo/lesões , Doenças Maxilares/prevenção & controle , Adulto , Aumento do Rebordo Alveolar , Reabsorção Óssea/prevenção & controle , Criança , Cemento Dentário/patologia , Dentina/patologia , Humanos , Doenças Periapicais/complicações , Prognóstico , Reabsorção da Raiz/terapia , Anquilose Dental/terapia , Avulsão Dentária/complicações , Coroa do Dente/lesões , Fraturas dos Dentes/terapia , Reimplante Dentário , Raiz Dentária/lesões
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...