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1.
BMC Psychiatry ; 20(1): 381, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32693789

RESUMO

BACKGROUND: Anxiety disorders during pregnancy are not routinely assessed in Sri Lanka despite being common and being associated with adverse pregnancy outcomes. Screening can facilitate early detection and management of anxiety and improve pregnancy outcomes. Our aim was to determine the validity of the Sinhala translation of the Perinatal Anxiety Screening Scale (PASS) to detect anxiety among Sri Lankan pregnant women. METHODS: A cross-sectional study was conducted in antenatal clinics of a teaching hospital in Colombo District. The PASS was translated to Sinhala using the standard translation/ back-translation method. Pregnant women (n = 221) were sequentially recruited and assessed by a psychiatrist until 81 women with anxiety disorder were diagnosed using the International Classification of Diseases-10 criteria (gold standard). The Sinhala translation of the PASS (PASS-S) was administered to all recruited women, including 140 women without anxiety. Receiver-Operating- Characteristic (ROC) analysis was performed, the optimal cut-off score for PASS-S was determined, and its validity was assessed using sensitivity, specificity, predictive values and positive and negative likelihood ratios. Internal consistency was assessed using Cronbach's alpha. Test-retest and inter-rater reliability for PASS-S score and anxiety classification were assessed using intra class correlation coefficient (ICC) and Cohen's kappa (k), respectively. RESULTS: The mean age (±SD) of women was 30(±5.8) years, and 53.7% were multiparous. A psychiatrist diagnosed anxiety disorder was made in 37.0% of women, while the PASS-S, at its optimal cut-off of ≥20, classified 37.5% of women as having anxiety disorders. The area under the ROC curve for the PASS-S was 0.96 (95%CI 0.94-0.99). Sensitivity, specificity and positive and negative predictive values of the PASS-S were 0.93 (95% CI 0.84-0.97), 0.90 (95% CI 0.83-0.94), 0.85 (95% CI 0.75-0.90) and 0.95 (95% CI 0.89-0.98), respectively. Positive and negative likelihood ratios were 8.8 (95% CI 5.3-14.5) and 0.08 (95%CI 0.04-0.18), respectively, and the internal consistency was high (Cronbach's alpha 0.95). Four-factor structures obtained by exploratory factor analysis were "acute anxiety and adjustment", "social anxiety, specific fears and trauma", "perfectionism and control" and "general anxiety".Test-retest reliability was high for the PASS-S score (ICC 0.85[95% CI 0.65-0.96]) and anxiety classification (k 0.77[95% CI 0.34-1.2]). Inter-interviewer reliability was also high (ICC 0.92[95% CI 0.81-0.97] for the PASS-S score and (k0.86 [95% CI 0.59-1.1] for anxiety classification). CONCLUSION: The Sinhala translation of the PASS is a valid and reliable instrument to screen for anxiety disorders among antenatal women in Sri Lanka.


Assuntos
Transtornos de Ansiedade , Ansiedade , Adulto , Ansiedade/diagnóstico , Transtornos de Ansiedade/diagnóstico , Estudos Transversais , Feminino , Humanos , Gravidez , Psicometria , Reprodutibilidade dos Testes , Sri Lanka , Adulto Jovem
2.
Endocr Connect ; 9(7): 676-686, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32567553

RESUMO

PURPOSE: Augmented survival of childhood nephroblastoma and neuroblastoma has increased long-term side effects such as metabolic syndrome (MetS). Risk stratification is difficult after abdominal radiation because waist circumference underestimates adiposity. We aimed to develop a strategy for determining MetS in irradiated survivors using an integrated biomarker profile and vascular ultrasonography. METHODS: The NCEP-ATPIII MetS-components, 14 additional serum biomarkers and 9 vascular measurements were assessed in a single-centre cohort of childhood nephroblastoma (n = 67) and neuroblastoma (n = 36) survivors and controls (n = 61). Multivariable regression models were used to study treatment effects. Principal component analysis (PCA) was used to study all biomarkers in a combined analysis, to identify patterns and correlations. RESULTS: After 27.5 years of follow-up, MetS occurred more often in survivors (14%) than controls (3%). Abdominal radiotherapy and nephrectomy, to a lesser extent, were associated with MetS and separate components and with several biomarker abnormalities. PCA of biomarkers revealed a pattern on PC1 from favourable lipid markers (HDL-cholesterol, adiponectin) towards unfavourable markers (triglycerides, LDL-cholesterol, apoB, uric acid). Abdominal radiotherapy was associated with the unfavourable biomarker profile (ß = 1.45, P = 0.001). Vascular measurements were not of added diagnostic value. CONCLUSIONS: Long-term childhood nephro- and neuroblastoma survivors frequently develop MetS. Additional assessment of biomarkers identified in PCA - adiponectin, LDL, apoB, and uric acid - may be used especially in abdominally irradiated survivors, to classify MetS as alternative for waist circumference. Vascular ultrasonography was not of added value.

3.
Crit Rev Oncol Hematol ; 133: 129-141, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30661649

RESUMO

Over the past decades, survival rates of childhood cancer have increased considerably from 5 to 30% in the early seventies to current rates exceeding 80%. This is due to the development of effective chemotherapy, surgery, radiotherapy and stem cell transplantation, combined with an optimized stratification of therapy and better supportive care regimens. As a consequence, active surveillance strategies of late sequelae have been developed to improve the quality of survival. Several epidemiological studies have reported an increased incidence of (components of) metabolic syndrome (MetS) and cardiovascular disease in childhood cancer survivors (CCS). Growth hormone deficiency (GHD) after cranial radiotherapy (CRT) has been previously described as an important cause of MetS. New insights suggest a role for abdominal radiotherapy as a determinant for MetS as well. The role of other risk factors, such as specific chemotherapeutic agents, steroids, gonadal impairment, thyroid morbidity and genetics, warrants further investigation. This knowledge is important to define subgroups of CCS that are at risk to develop (subclinical) MetS features. These survivors might benefit from standard surveillance and early interventions, for example lifestyle and diet advice and medical treatment, thereby preventing the development of cardiovascular disease.


Assuntos
Sobreviventes de Câncer , Doenças Cardiovasculares/epidemiologia , Síndrome Metabólica/epidemiologia , Neoplasias/epidemiologia , Adulto , Idade de Início , Sobreviventes de Câncer/estatística & dados numéricos , Doenças Cardiovasculares/etiologia , Criança , Humanos , Incidência , Síndrome Metabólica/complicações , Neoplasias/complicações , Fatores de Risco
4.
Phys Rev Lett ; 118(24): 246601, 2017 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-28665644

RESUMO

Recent theoretical studies of topologically nontrivial electronic states in Kondo insulators have pointed to the importance of spin-orbit coupling (SOC) for stabilizing these states. However, systematic experimental studies that tune the SOC parameter λ_{SOC} in Kondo insulators remain elusive. The main reason is that variations of (chemical) pressure or doping strongly influence the Kondo coupling J_{K} and the chemical potential µ-both essential parameters determining the ground state of the material-and thus possible λ_{SOC} tuning effects have remained unnoticed. Here, we present the successful growth of the substitution series Ce_{3}Bi_{4}(Pt_{1-x}Pd_{x})_{3} (0≤x≤1) of the archetypal (noncentrosymmetric) Kondo insulator Ce_{3}Bi_{4}Pt_{3}. The Pt-Pd substitution is isostructural, isoelectronic, and isosize, and it therefore is likely to leave J_{K} and µ essentially unchanged. By contrast, the large mass difference between the 5d element Pt and the 4d element Pd leads to a large difference in λ_{SOC}, which thus is the dominating tuning parameter in the series. Surprisingly, with increasing x (decreasing λ_{SOC}), we observe a Kondo insulator to semimetal transition, demonstrating an unprecedented drastic influence of the SOC. The fully substituted end compound Ce_{3}Bi_{4}Pd_{3} shows thermodynamic signatures of a recently predicted Weyl-Kondo semimetal.

5.
Osteoporos Int ; 26(2): 521-9, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25209410

RESUMO

SUMMARY: More than 45 % of long-term childhood cancer survivors (CCS) were diagnosed with osteopenia. Our data suggest that greater awareness for osteopenia is warranted in long-term CCS, especially in survivors who are older than 30 years, male, and underweight and were treated with cranial-spinal radiotherapy and/or steroids. INTRODUCTION: Osteopenia is a potential complication of childhood cancer treatment, but the magnitude of this problem in survivors is unknown. We examined (determinants of) bone mineral density (BMD) status in long-term survivors of adult childhood cancer. METHODS: This retrospective single-centre cohort study included 346 subjects with the most common types of childhood cancer. Subjects had a median age at diagnosis of 7.0 years (range 0.1-16.8 years), a median age at follow-up of 24.5 years (range 18.0-47.6 years) and a median follow-up time of 16.7 years (range 5.6-39.9 years). Total body BMD (BMDTB) and BMD of the lumbar spine (BMDLS) were measured by dual X-ray absorptiometry. Osteopenia was defined as BMD standardized deviation score (SDS) below -1. RESULTS: Survivors had a lower BMDTB and BMDLS (mean SDS -0.55; p<0.001 and -0.30; p<0.001, respectively) as compared to healthy peers. Osteopenia (BMDTB and/or BMDLS) was present in 45% of the survivors. Multivariate logistic regression analyses identified age at diagnosis<12 years, age>30 years at follow-up, male gender, underweight at follow-up and treatment with cranial-spinal radiotherapy or prednisone as independent prognostic factors for osteopenia. CONCLUSIONS: This large cohort of childhood cancer survivors identified osteopenia in 45% of CCS. This indicates that greater awareness is warranted, especially in survivors who are older than 30 years, male, have underweight and were treated with cranial-spinal radiotherapy and/or steroids.


Assuntos
Doenças Ósseas Metabólicas/diagnóstico por imagem , Neoplasias/terapia , Absorciometria de Fóton , Adolescente , Adulto , Densidade Óssea/fisiologia , Doenças Ósseas Metabólicas/complicações , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Vértebras Lombares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Neoplasias/complicações , Estudos Retrospectivos , Fatores de Risco , Sobreviventes , Resultado do Tratamento , Adulto Jovem
6.
Nat Mater ; 12(12): 1096-101, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24056804

RESUMO

The increasing worldwide energy consumption calls for the design of more efficient energy systems. Thermoelectrics could be used to convert waste heat back to useful electric energy if only more efficient materials were available. The ideal thermoelectric material combines high electrical conductivity and thermopower with low thermal conductivity. In this regard, the intermetallic type-I clathrates show promise with their exceedingly low lattice thermal conductivities. Here we report the successful incorporation of cerium as a guest atom into the clathrate crystal structure. In many simpler intermetallic compounds, this rare earth element is known to lead, through the Kondo interaction, to strong correlation phenomena including the occurrence of giant thermopowers at low temperatures. Indeed, we observe a 50% enhancement of the thermopower compared with a rare-earth-free reference material. Importantly, this enhancement occurs at high temperatures and we suggest that a rattling-enhanced Kondo interaction underlies this effect.

7.
Ann Oncol ; 23(6): 1626-32, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22048153

RESUMO

BACKGROUND: Aim of this study was to investigate the long-term endocrine effects of treatment of childhood non-Hodgkin lymphoma (NHL). PATIENTS AND METHODS: A single-center cohort of 84 survivors (22 females) was included in this retrospective study. Median age was 21 years (9-40 years) and time after cessation of therapy 12 years (4-30 years). Height, weight, percentage fat, lean body mass (LBM), bone mineral content (BMC), bone mineral density of total body (BMD(TB)) and bone mineral density of lumbar spine (BMD(LS)) were measured. Thyroid-stimulating hormone (TSH), free thyroxin (fT4), insulin-like growth factor-1 (IGF-1), inhibin B and anti-müllerian hormone (AMH) levels were measured. Results were compared with Dutch controls. RESULTS: Height was lower in survivors [mean standard deviation score (SDS) -0.36, P = 0.002], but further analysis showed that shorter stature was already present at diagnosis (mean SDS -0.28, P = 0.023). Body mass index, percentage fat, BMC, BMD(TB) and BMD(LS) were not different from controls. LBM was lower in survivors (mean SDS -0.47, P = 0.008). TSH, fT4 and IGF-1 were normal in all survivors. Three of 20 adult females had low AMH levels and 23 of 42 adult males had low inhibin B levels. CONCLUSIONS: Twelve years after cessation of treatment, NHL survivors did not develop adiposity, osteoporosis or thyroid disease. Male survivors may be at risk for infertility.


Assuntos
Antineoplásicos/efeitos adversos , Hormônios/sangue , Linfoma não Hodgkin/tratamento farmacológico , Sobreviventes , Adolescente , Adulto , Antineoplásicos/uso terapêutico , Composição Corporal , Pesos e Medidas Corporais , Densidade Óssea , Estudos de Casos e Controles , Criança , Pré-Escolar , Sistema Endócrino/efeitos dos fármacos , Feminino , Seguimentos , Humanos , Vértebras Lombares/diagnóstico por imagem , Linfoma não Hodgkin/sangue , Masculino , Radiografia , Adulto Jovem
8.
Ned Tijdschr Tandheelkd ; 118(5): 277-81, 2011 May.
Artigo em Holandês | MEDLINE | ID: mdl-21661249

RESUMO

'Dentures: A question of grinning and bearing it' is not just the title of a 25-year-old thesis, but it also reflects the content well. Dissatisfaction with complete dentures is not only determined by the quality of the dentures and the oral conditions, but also and just as much by the patient's capacity to adapt to and accept the dentures. In order to treat an edentulous patient adequately, an oral healthcare provider should pay special attention to these aspects. After 25 years of further scientific study, this conclusion is still true. The current care standard for edentulous patients with atrophy of the residual mandibular alveolar ridge is an overdenture supported by 2 implants. For edentulous patients with a solid residual mandibular alveolar ridge, conventional complete dentures are the first choice of treatment. Only in cases of obvious remaining complaints, should an implant-supported overdenture be considered.


Assuntos
Prótese Dentária Fixada por Implante/métodos , Retenção de Dentadura , Dentaduras , Arcada Edêntula/reabilitação , Satisfação do Paciente , Revestimento de Dentadura , Humanos
9.
Ned Tijdschr Tandheelkd ; 118(11): 563-7, 2011 Nov.
Artigo em Holandês | MEDLINE | ID: mdl-22235519

RESUMO

When designing complete dentures, consideration should not only be given to the occlusal concept but also to the occlusal system as a whole. An important part of that system is the position of the artificial teeth. This prosthetic part of the occlusal system is directly related to the tongue, the floor of the mouth, the cheeks and the lips. The artificial teeth of the mandibular dentures have to be positioned in the so-called 'neutral zone' of the edentulous mandible. The neutral zone is the stress-free area between the tongue on one side and, on the other side, the mimic muscles, which are responsible for the movement of the lips and cheeks. Moreover, the maxillary posterior artificial teeth and the supporting acrylic surfaces of the maxillary denture have an important function in providing support for the upper lip and cheeks in order to prevent a 'denture look' appearance.


Assuntos
Oclusão Dentária Balanceada , Planejamento de Dentadura , Prótese Total , Bases de Dentadura , Humanos , Modelos Dentários
10.
Ann Oncol ; 21(5): 1121-6, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19850641

RESUMO

BACKGROUND: Adult survivors of childhood cancer have been reported to have an increased risk of late sequels. A cluster of abnormalities that contribute to the metabolic syndrome may be expressed at a higher level and therefore result in an increased risk for diabetes mellitus and cardiovascular diseases. PATIENTS AND METHODS: We investigated a single-centre cohort of 500 adult survivors (228 females) of childhood cancer, median age 28 years (range 18-59 years) and median follow-up time 19 years (range 6-49 years). We measured total cholesterol, high-density lipoprotein-cholesterol, systolic and diastolic blood pressure, body mass index and the prevalence of diabetes mellitus. Data from the epidemiological Monitoring van Risicofactoren en Gezondheid in Nederland (MORGEN) study were used to calculate standard deviation scores as normative values. RESULTS: The criteria of the metabolic syndrome were met in 13% of the total cohort. Acute lymphoblastic leukaemia (ALL) survivors treated with cranial irradiation had an increased risk of developing the metabolic syndrome compared with ALL survivors not treated with cranial irradiation (23% versus 7%, P = 0.011), probably determined by higher prevalence of overweight and hypertension. CONCLUSION: Adult survivors of childhood cancer, especially those treated with cranial irradiation, are at increased risk of developing the metabolic syndrome.


Assuntos
Doenças Cardiovasculares/etiologia , Diabetes Mellitus/etiologia , Síndrome Metabólica/etiologia , Neoplasias/complicações , Neoplasias/terapia , Sobreviventes , Adolescente , Adulto , Antineoplásicos/efeitos adversos , Pressão Sanguínea , Índice de Massa Corporal , Estudos de Coortes , Terapia Combinada , Irradiação Craniana/efeitos adversos , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/mortalidade , Prognóstico , Taxa de Sobrevida , Adulto Jovem
11.
Ned Tijdschr Tandheelkd ; 116(11): 593-6, 2009 Nov.
Artigo em Holandês | MEDLINE | ID: mdl-19999669

RESUMO

Since there are many ways of preserving a natural dentition, if necessary with support of solitary crowns and fixed partial dentures, sometimes on dental implants, removable partial dentures are nowadays primarily indicated in patients with complaints about missing teeth in the aesthetic zone, which cannot be solved in another way. In addition to this, a removable partial denture is indicated in patients with extremely reduced dentitions or large or multiple edentulous areas, in patients with severe periodontitis or excessive loss of alveolar bone, in patients who are physically or emotionally vulnerable, as an interim solution on the way to edentulousness, as a temporary solution waiting for more extensive treatment and for patients who cannot afford an alternative.


Assuntos
Prótese Parcial Removível , Estética Dentária , Arcada Parcialmente Edêntula/terapia , Humanos , Higiene Bucal
12.
J Dent Res ; 86(3): 276-80, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17314262

RESUMO

Mandibular implant overdentures increase satisfaction and the quality of life of edentulous individuals. Long-term aftercare and costs may depend on the type of overdentures. One hundred and ten individuals received one of 3 types of implant-retained overdentures, randomly assigned, and were evaluated with respect to aftercare and costs. The follow-up time was 8 years, with only seven drop-outs. No significant differences (Kruskal-Wallis test) were observed for direct costs of aftercare (p = 0.94). The initial costs constituted 75% of the total costs and were significantly higher in the group with a bar on 4 implants, compared with the group with a bar on 2 implants and the group with ball attachments on 2 implants (p = 0.018). The last group needed a significantly higher number of prosthodontist-patient aftercare contacts, mostly for re-adjustment of the retentive system. It can be concluded that an overdenture with a bar on 2 implants might be the most efficient in the long term.


Assuntos
Prótese Dentária Fixada por Implante/economia , Planejamento de Dentadura/economia , Revestimento de Dentadura/economia , Arcada Edêntula/reabilitação , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise Custo-Benefício , Implantação Dentária Endóssea/economia , Retenção de Dentadura/economia , Retenção de Dentadura/instrumentação , Prótese Total Inferior/economia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Cuidados Pós-Operatórios/economia
13.
Ned Tijdschr Tandheelkd ; 112(9): 330-1, 2005 Sep.
Artigo em Holandês | MEDLINE | ID: mdl-16184909

RESUMO

This article is focusing on incorporation of implant overdentures into the dental curriculum. For mandibular edentulism, an implant-retained overdenture should nowadays be considered a first choice for prosthodontic care, if not the standard of care. Yet, it is not incorporated in practical teaching today. Curriculum change is always difficult. The needs of our patients specifically, and those of society generally, should be primarily drivers of innovation of the curriculum. Therefore, Dutch dental schools should make sure that graduated students are experts in analyzing edentulous patients' problems, in considering possible treatments, and in carrying out the standard of care.


Assuntos
Prótese Dentária Fixada por Implante , Educação em Odontologia , Arcada Parcialmente Edêntula/terapia , Currículo , Assistência Odontológica/normas , Educação em Odontologia/métodos , Educação em Odontologia/normas , Humanos , Países Baixos
15.
J Dent Res ; 83(8): 630-3, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15271972

RESUMO

Studies have shown that mandibular implant overdentures significantly increase satisfaction and quality of life of edentulous elders. Improved chewing ability appears to have a positive impact on nutritional state. Therefore, it is important to determine the best design of this prosthesis over the long term. In this randomized controlled trial, three groups of edentulous participants with atrophic mandibles wore 3 types of implant overdentures. During an eight-year follow-up, only seven of the 110 participants had dropped out of this study. Almost all participants were still satisfied with their overdentures. Participant satisfaction concerning retention and stability of the mandibular overdenture had decreased significantly in the two-implant ball attachment group, whereas the opinion of participants in the single- and triple-bar groups was still at the same level. The long-term results suggest that a mandibular overdenture retained by 2 implants with a single bar may be the best treatment strategy for edentulous people with atrophic ridges.


Assuntos
Implantação Dentária Endóssea , Implantes Dentários , Prótese Dentária Fixada por Implante , Revestimento de Dentadura , Mandíbula/cirurgia , Satisfação do Paciente , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Atrofia , Dente Suporte , Planejamento de Prótese Dentária , Encaixe de Precisão de Dentadura , Retenção de Dentadura , Prótese Total Inferior , Feminino , Seguimentos , Humanos , Arcada Parcialmente Edêntula/reabilitação , Arcada Parcialmente Edêntula/cirurgia , Masculino , Mandíbula/patologia , Pessoa de Meia-Idade , Ajustamento Social , Resultado do Tratamento
16.
Ned Tijdschr Tandheelkd ; 110(9): 350-4, 2003 Sep.
Artigo em Holandês | MEDLINE | ID: mdl-14533342

RESUMO

Beautiful teeth, visible when smiling, are in line with the present ideal of beauty. The display of teeth when smiling is determined by the smile line: the projection of the lower border of the upper lip on the maxillary teeth when smiling. On the basis of a literature search the determining methods of the smile line are discussed, demographic data of the position of the smile line are given, and factors of influence are examined. There is no unequivocal method for determining the position of the smile line. A rough distinction can be made between qualitative and (semi)-quantitative methods. The (semi)-quantitative methods have clear advantages for research purposes, but their reliability is unknown. It was demonstrated that among minimally 40% of subjects the maxillary gingiva was not visible when smiling. The mandibular gingiva was not visible when smiling among more than 90% of subjects. Furthermore, it appeared that among women the smile line was on average higher situated than among men and that it has not yet been proven that the smile line will be situated lower when growing older.


Assuntos
Estética Dentária , Lábio/fisiologia , Sorriso , Fatores Etários , Feminino , Humanos , Lábio/anatomia & histologia , Masculino , Fatores Sexuais
17.
Ned Tijdschr Tandheelkd ; 110(2): 69-73, 2003 Feb.
Artigo em Holandês | MEDLINE | ID: mdl-12621998

RESUMO

In the non-Caucasian population the skin and oral tissues show pigmentation to a variable degree, but much more than in Caucasian. When a person becomes edentulous, the tissues containing oral pigmentation disappear. The patient's ethnic background gives no information to predict the characteristics of individual oral pigmentation; other sources have to be found. The mucosal pigmentation of 106 non-Caucasian, dentate people in Amsterdam and Los Angeles was investigated; a classification-chart of oral pigmentation with six types was designed. This tool makes it possible to help patient, dentist and dental technician to choose an accurate simulation of the contour of oral pigmentation in a denture. It is recommended to document the individual pigmentation before extractions are performed.


Assuntos
Dentaduras/normas , Mucosa Bucal , Pigmentação/fisiologia , Grupos Raciais , Humanos , Mucosa Bucal/patologia , Mucosa Bucal/fisiologia , Boca Edêntula/classificação , Boca Edêntula/patologia
18.
J Dent Res ; 81(12): 856-9, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12454102

RESUMO

In this prospective study, we determined the effects of the time interval between irradiation and implant therapy, implant location, bone-resection surgery, and irradiation dose on implant survival. We analyzed the survival of 446 implants inserted after radiotherapy over a period of up to 14 years in 130 consecutive patients treated for oral cancer. The 10-year overall Kaplan-Meier implant survival percentage is 78%. The difference in survival percentages of implants inserted < 1 year and >/= 1 year after irradiation (76% and 81%, respectively) is not significant. We concluded that implant survival is significantly influenced by the location (maxilla or mandible, 59% and 85%, respectively; p = 0.001), by the incidence of bone-resection surgery in the jaw where the implant was installed (p = 0.04), and by the irradiation dose at the implant site (< 50 Gray or >/= 50 Gray, p = 0.05).


Assuntos
Irradiação Craniana/efeitos adversos , Implantação Dentária Endóssea , Implantes Dentários , Falha de Restauração Dentária , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Mandíbula/cirurgia , Maxila/cirurgia , Pessoa de Meia-Idade , Neoplasias Bucais/radioterapia , Modelos de Riscos Proporcionais , Estudos Prospectivos , Dosagem Radioterapêutica , Análise de Sobrevida , Fatores de Tempo
19.
Biomaterials ; 23(4): 1261-8, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11794323

RESUMO

The osteoconductive properties of calcium phosphate cements (CPCs) may be improved by the addition of growth factors, such as recombinant human transforming growth factor-beta1 (rhTGF-beta1). Previously we have shown that rhTGF-beta1 was released from cement enriched with rhTGF-beta1 and subsequently stimulated the differentiation of pre-osteoblastic cells from adult rat long bones. It is unknown whether the addition of rhTGF-beta1 changes the material properties of this alpha-tricalcium-phosphate (alpha-TCP)/tetracalcium-phosphate-monoxide (TeCP)/dicalcium-phosphate-dihydrate (DCPD) cement, and what the characteristics of the release of rhTGF-beta1 from this CPC are. Therefore, in the present study we determined the release of rhTGF-beta1 from cement pellets in vitro. The possible intervening effects of the CPC modification for intermixing rhTGF-beta1 on physicochemical properties were studied by assessing the compressive strength and setting time, as well as crystallinity, calcium to phosphorus ratio, porosity and microscopic structure. Most of the previously incorporated rhTGF-beta1 in the cement pellets was released within the first 48 h. For all concentrations of rhTGF-beta1 intermixed (100 ng-2.5 mg/g CPC), approximately 0.5% of the amount of rhTGF-beta1 incorporated initially was released in the first 2 h, increasing to 1.0% after 48 h. The release of rhTGF-beta1 continued hereafter at a rate of about 0.1% up to 1 week, after which no additional release was found. The initial setting time, nor the final setting time was changed in control cement without rhTGF-beta1 (standard CPC) or in cement modified for rhTGF-beta1 (modified CPC) at 20 degrees C and 37 degrees C. Setting times were more than six times decreased at 37 degrees C compared to 20 degrees C. The compressive strength was initially low for both standard CPC and modified CPC, after which it increased between 24 h and 8 weeks. The compressive strength for the modified CPC was significantly higher compared with standard at 1, 2, and 8 weeks after mixing. X-ray diffraction revealed that both standard and modified CPC changed similarly from the original components into crystalline apatite. The calcium to phosphorus ratio as determined by an electron microprobe did not differ at all time points measured for standard CPC and modified CPC. In both standard CPC and modified CPC the separated particles became connected by crystals, forming a structure in which the particles could hardly be recognised in a densifying matrix with some small pores. The present study shows that the calcium phosphate cement is not severely changed by modification for the addition of rhTGF-beta1. The addition of rhTGF-beta1 in CPC enhances the biologic response as shown in our previous study and did not interfere with the aimed physical and chemical properties as shown in this study. We conclude that the addition of rhTGF-beta1 enlarges the potential of the CPC in bone replacement therapy.


Assuntos
Cimentos Ósseos , Fosfatos de Cálcio , Fator de Crescimento Transformador beta/administração & dosagem , Animais , Fenômenos Químicos , Físico-Química , Força Compressiva , Preparações de Ação Retardada , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica , Microscopia Eletrônica de Varredura , Ratos , Proteínas Recombinantes/administração & dosagem , Fator de Crescimento Transformador beta1 , Difração de Raios X
20.
J Biomed Mater Res ; 59(2): 265-72, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11745562

RESUMO

The bone regenerative properties of calcium phosphate cements (CPCs) may be improved by the addition of growth factors, such as recombinant human transforming growth factor-beta1 (rhTGF-beta1). Previously, we showed that rhTGF-beta1 in CPC stimulated the differentiation of preosteoblastic cells from adult rat long bones. The intermixing of rhTGF-beta1 in CPC, which was subsequently applied to rat calvarial defects, enhanced bone growth around the cement and increased the degradation of the cement. However, it is unknown whether the addition of rhTGF-beta1 changes the material properties of CPC and what the characteristics of the release of rhTGF-beta1 from CPC are. Therefore, we determined in this study the release of rhTGF-beta1, in vitro, from the cement pellets as implanted in the rat calvariae. The possible intervening effects of rhTGF-beta1 intermixing on the clinical compliance of CPC were studied through an assessment of its compressive strength and setting time, as well as its crystallinity, calcium-to-phosphorus ratio, porosity, and microscopic structure. We prepared CPC by mixing calcium phosphate powder (58% alpha-tricalcium phosphate, 25% anhydrous dicalcium phosphate, 8.5% calcium carbonate, and 8.5% hydroxyapatite) with a liquid (3 g/mL). The liquid for standard CPC consisted of water with 4% disodium hydrogen phosphate, whereas the liquid for modified CPC was mixed with an equal amount of 4 mM hydrochloride with 0.2% bovine serum albumin. The hydrochloride liquid contained rhTGF-beta1 in different concentrations for the release experiments. Most of the rhTGF-beta1 incorporated in the cement pellets was released within the first 48 h. For all concentrations of intermixed rhTGF-beta1 (100 ng to 2.5 mg/g of CPC), approximately 0.5% was released in the first 4 h, increasing to 1.0% after 48 h. Further release was only about 0.1% from 2 days to 8 weeks. CPC modification slightly increased the initial setting time at 20 degrees C from 2.6 to 5 min but had no effect on the final setting time of CPC at 20 degrees C or the initial and final setting times at 37 degrees C. The compressive strength was increased from 18 MPa in the standard CPC to 28 MPa in the modified CPC only 4 h after mixing. The compressive strength diminished in the modified CPC between 24 h and 8 weeks from 55 to 25 MPa. No other significant change was found with the CPC modification for rhTGF-beta1. X-ray diffraction revealed that standard and modified CPCs changed similarly from the original components, alpha-tricalcium phosphate and anhydrous dicalcium phosphate, into an apatite cement. The calcium-to-phosphorus ratio, as determined with an electron microprobe, did not differ for standard CPC and modified CPC. Standard and modified CPCs became dense and homogeneous structures after 24 h, but the modified CPC contained more crystal plaques than the standard CPC, as observed with scanning electron microscopy (SEM). SEM and back- scattered electron images revealed that after 8 weeks the cements showed equally and uniformly dense structures with microscopic pores (<1 microm). Both CPCs showed fewer crystal plaques at 8 weeks than at 24 h. This study shows that CPC is not severely changed by its modification for rhTGF-beta1. The prolonged setting time of modified cement may affect the clinical handling but is still within acceptable limits. The compressive strength for both standard and modified cements was within the range of thin trabecular bone; therefore, both CPCs can withstand equal mechanical loading. The faster diminishing compressive strength of modified cement from 24 h to 8 weeks likely results in early breakdown and so might be favorable for bone regeneration. Together with the beneficial effects on bone regeneration from the addition of rhTGF-beta1 to CPC, as shown in our previous studies, we conclude that the envisaged applications for CPC in bone defects are upgraded by the intermixing of rhTGF-beta1. Therefore, the combination of CPC and rhTGF-beta1 forms a promising synthetic bone graft.


Assuntos
Cimentos Ósseos , Fosfatos de Cálcio , Fator de Crescimento Transformador beta/administração & dosagem , Fator de Crescimento Transformador beta/farmacocinética , Substitutos Ósseos , Força Compressiva , Preparações de Ação Retardada , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/farmacocinética , Difração de Raios X
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