Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 72
Filter
1.
Med Oral Patol Oral Cir Bucal ; 29(2): e273-e279, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-37992142

ABSTRACT

BACKGROUND: The differentiation between primary and metastatic salivary gland neoplasms (SGNs) helps in determining appropriate management strategies, including the need for additional diagnostic tests, surveillance, or aggressive treatment. The purpose of this study was to identify and quantify the immature and mature dendritic cells (DCs) in metastatic and no metastatic SGNs and determine its association with clinicopathological findings. MATERIAL AND METHODS: Cross-sectional, observational, and descriptive study that includes 33 malignant salivary gland neoplasms [MSGN (6, 18.1% metastatic)], and 22 pleomorphic adenomas (PA), as a control group. Clinical and histopathological characteristics were obtained. Immunohistochemistry for human leukocyte antigen D-related (HLA-DR), CD1a, CD83, and Ki-67 proteins was done. Positive intra- and peritumoral DCs were counted. RESULTS: Individuals with MSGN had a lower density of intratumoral HLA-DR+ cells than those with PA (p=0.001), Ki-67 immunostaining was significantly higher in MSGN than in PA (6% vs. 1.4%, p<0.001). Metastatic MSGN showed less intratumoral CD1a+ than non-metastatic (3.2 vs. 165.1, p=0.001). No differences in intra- and peritumoral CD83+ cells were found between benign and malignant SGN. CONCLUSIONS: These results suggest that the immune-protective function of intratumoral DCs is compromised in MSGNs. DCs markers may represent useful prediction tools for metastases in salivary gland malignancies, with crucial implications in the implementation of appropriate disease management strategies.


Subject(s)
Adenoma, Pleomorphic , Salivary Gland Neoplasms , Humans , Cross-Sectional Studies , Ki-67 Antigen , Dendritic Cells , HLA-DR Antigens
2.
Article in English | MEDLINE | ID: mdl-38040520

ABSTRACT

Primary oral and sinonasal mucosal melanomas (POSNMMs) are aggressive neoplasms with limited therapeutic alternatives. The aim of this review was to characterize the demographic, clinical, immunohistochemical, and molecular information regarding these tumors in the Latin American population. Articles published in English, Spanish, or Portuguese (1990-2022) retrieved from the PubMed/MEDLINE, Scopus, CAS, Web of Science, EBSCO, and Google Academic databases were included. Thirty-three studies, with a total of 1212 cases, were identified. Clinicopathological data were available for 870 cases and immunohistochemical and/or molecular information for 342. Nineteen studies (57.6%) reported cases of oral melanoma, three (9.1%) sinonasal melanoma, and 11 (33.3%) oral and sinonasal melanoma. Fifteen studies (45.5%) provided only clinicopathological data, 12 (36.4%) reported only immunohistochemical data, two (6.1%) shared clinicopathological and immunohistochemical data, one (3.0%) offered clinicopathological, immunohistochemical, and molecular data, one (3.0%) provided immunohistochemical and molecular data, one (3.0%) clinicopathological and molecular data, and one (3.0%) only molecular data. The mean age of individuals with POSNMMs was 58 years, and slightly more were male (male 51.3%, female 48.7%). In Latin America, POSNMMs are a rare but aggressive malignancy with a poor prognosis and limited treatment options. Although molecular data and targeted therapy are still being researched, data from Latin America indicate the need for multicenter collaborative clinical trials to unite individual and isolated efforts.

3.
J Opt Soc Am A Opt Image Sci Vis ; 40(7): 1451-1467, 2023 Jul 01.
Article in English | MEDLINE | ID: mdl-37706747

ABSTRACT

Using a mathematical approach, this paper presents a generalization of semi-analytical expressions for the point spread function (PSF) of plenoptic cameras. The model is applicable in the standard regime of the scalar diffraction theory while the extension to arbitrary main lens transmission functions generalizes a priori formalism. The accuracy and applicability of the model is well verified against the exact Rayleigh-Sommerfeld diffraction integral and a rigorous proof of convergence for the PSF series expression is made. Since vignetting can never be fully eliminated, it is critical to inspect the image degradation it poses through distortions. For what we believe is the first time, diffractive distortions in the diffraction-limited plenoptic camera are closely examined and demonstrated to exceed those that would otherwise be estimated by a geometrical optics formalism, further justifying the necessity of an approach based on wave optics. Microlenses subject to the edge diffraction effects of the main lens vignetting are shown to translate into radial distortions of increasing severity and instability with defocus. The distortions due to vignetting are found to be typically bound by the radius of the geometrical defocus in the image plane, while objects confined to the depth of field give rise to merely subpixel distortions.

4.
Appl Opt ; 62(16): 4228-4235, 2023 Jun 01.
Article in English | MEDLINE | ID: mdl-37706910

ABSTRACT

A practical guide for the easy implementation of a Fourier light-field microscope is reported. The Fourier light-field concept applied to microscopy allows the capture in real time of a series of 2D orthographic images of microscopic thick dynamic samples. Such perspective images contain spatial and angular information of the light-field emitted by the sample. A feature of this technology is the tight requirement of a double optical conjugation relationship, and also the requirement of NA matching. For these reasons, the Fourier light-field microscope being a non-complex optical system, a clear protocol on how to set up the optical elements accurately is needed. In this sense, this guide is aimed to simplify the implementation process, with an optical bench and off-the-shelf components. This will help the widespread use of this recent technology.

5.
Opt Express ; 30(1): 511-521, 2022 Jan 03.
Article in English | MEDLINE | ID: mdl-35201227

ABSTRACT

We report a scanning non-confocal fluorescence microscopy scheme that provides images with optical sectioning and with a lateral resolution that surpasses by a factor of two the diffraction resolution limit. This technique is based on the type-1 microscopy concept combined with patterned illumination. The method does not require the application of phase-shifting or post-processing algorithms and provides artifact-free superresolved 3D images. We have validated the theory by means of experimental data.

6.
Opt Express ; 29(21): 33357-33366, 2021 Oct 11.
Article in English | MEDLINE | ID: mdl-34809149

ABSTRACT

The use of microlens arrays for lightfield display has the drawback of providing images with strong chromatic aliasing. To overcome this problem, pinhole-type lightfield monitors are proposed. This paper is devoted to evaluating the capability for such lightfield monitors to offer the user a convincing 3D experience with images with enough brightness and continuous aspect. Thus, we have designed a psychophysical test specifically adapted for lightfield monitors, which allowed us to confirm the usability of pinhole-type monitors.

7.
Sci Rep ; 11(1): 10750, 2021 05 24.
Article in English | MEDLINE | ID: mdl-34031431

ABSTRACT

The management of wavelength routed optical mesh networks is complex with many potential light path routes and numerous physical layer impairments to transmission performance. This complexity can be reduced by applying the ideas of abstraction from computer science where different equipment is described in the same basic terms. The noise-to-signal ratio can be used as a metric to describe the quality of transmission performance of a signal propagated through a network element and accumulates additively through a sequence of such elements allowing the estimation of end-to-end performance. This study aims to explore the robustness of the noise-to-signal ratio metric in an installed fibre infrastructure. We show that the abstracted noise-to-signal ratio is independent of the observers and their location. We confirm that the abstracted noise-to-signal ratio can reasonably predict the performance of light-paths subsequently set in our network. Having a robust network element abstraction that can be incorporated into routeing engines allows the network management controller to make decisions on the most effective way to use the network resources in terms of the routeing and data coding format.

8.
Oral Dis ; 24(1-2): 210-214, 2018 Mar.
Article in English | MEDLINE | ID: mdl-29480634

ABSTRACT

BACKGROUND: Although HPV emerged as a crucial carcinogenic and prognostic biomarker in head and neck cancer, and considering the increase in HPV-associated oral lesions (HPV-OLs) in HIV individuals, molecular information about HPV-OLs is scarce; thus, our aim was to determine viral loads in HPV-OLs from HIV/AIDS individuals. METHODS: HIV/AIDS subjects with HPV-OL were included in this cross-sectional study. Following informed consent, biopsies were obtained. HPV detection and typing were carried out by PCR and sequencing (MY09/11, GP5+/6+). HPV-13 and HPV-32 loads were determined by a high-resolution melting assay. For statistical analysis, X2 , Fisher's exact, and Mann-Whitney U tests were applied, using SPSS software (v.23). RESULTS: Twenty-nine HIV subjects (median age 38 years, 93% males) were included. Most were AIDS individuals (72.4%) under HAART (89.7%). Twenty-two (75.9%) participants had more than one HPV-OL (four with florid presentations), mostly multifocal epithelial hyperplasia (62%), being HPV-13 (26%) and HPV-32 (31%) the most frequent types. HPV load was higher in individuals with multiple HPV-OLs than in solitary lesions (4.9 vs. 3.2 Log10 copies/ml, p = .090) and in HPV-32+ than in HPV-13+ (8.3 vs. 6.4 Log10 copies/ml, p = .014). CONCLUSIONS: Multiple HPV-OLs showed high HPV loads, possibly indicating transcriptional activity of the virus; however, in the HIV setting, the individual and local immunological response could be the key process.


Subject(s)
Acquired Immunodeficiency Syndrome/complications , Mouth Diseases/virology , Papillomaviridae , Papillomavirus Infections/virology , Viral Load , Adult , Cross-Sectional Studies , DNA, Viral/analysis , Female , Humans , Male , Middle Aged , Papillomaviridae/genetics , Papillomaviridae/isolation & purification
9.
Biomed Opt Express ; 9(1): 335-346, 2018 Jan 01.
Article in English | MEDLINE | ID: mdl-29359107

ABSTRACT

In this work, Fourier integral microscope (FIMic), an ultimate design of 3D-integral microscopy, is presented. By placing a multiplexing microlens array at the aperture stop of the microscope objective of the host microscope, FIMic shows extended depth of field and enhanced lateral resolution in comparison with regular integral microscopy. As FIMic directly produces a set of orthographic views of the 3D-micrometer-sized sample, it is suitable for real-time imaging. Following regular integral-imaging reconstruction algorithms, a 2.75-fold enhanced depth of field and [Formula: see text]-time better spatial resolution in comparison with conventional integral microscopy is reported. Our claims are supported by theoretical analysis and experimental images of a resolution test target, cotton fibers, and in-vivo 3D-imaging of biological specimens.

10.
J Clin Pharm Ther ; 43(2): 202-208, 2018 Apr.
Article in English | MEDLINE | ID: mdl-28948645

ABSTRACT

WHAT IS KNOWN AND OBJECTIVE: Chemotherapy (CT)-associated oral mucositis (OM) is one of the most debilitating and painful side effects in oncology patients, with limited effective management options. During CT, matrix metalloproteinases (MMPs) are upregulated, causing damage in mucosal and submucosal tissues, and playing a key role in OM; therefore, the use of subantimicrobial doxycycline as a MMP inhibitor may represent a potential approach for OM management. The aim of this clinical trial was to evaluate the efficacy and safety of low doses of doxycycline in OM development in individuals with acute leukaemia (AL) during CT. METHODS: Randomized controlled clinical trial (Registration No. NCT01087476) performed in adult AL patients scheduled to receive CT (September 2010-October 2014). Individuals were stratified by leukaemia type and assigned randomly to receive doxycycline hyclate (50 mg/d) (doxycycline group: DG) or placebo (placebo group: PG) before and during CT. Included subjects had a baseline oral examination and thereafter 3 times a week during 21 days. The primary outcome was OM development. RESULTS AND DISCUSSION: One hundred and forty-seven AL subjects were enrolled: 74 in DG and 73 in PG; baseline characteristics between groups were comparable. During follow-up, 15 (10.2%) individuals developed OM; no differences between treatment groups were found (DG:8.1%, PG:12.3%; P = .59). The mean OM Assessment Scale score was 2.51, without differences between groups (DG:2.7, PG:2.4; P = .65). Low baseline blood albumin levels in the OM-affected individuals were identified, revealing the effect of systemic deterioration as a predisposing factor for OM development. No adverse effects were observed. WHAT IS NEW AND CONCLUSION: Subantimicrobial doses of doxycycline did not reduce the incidence, onset, duration or severity of OM.


Subject(s)
Antineoplastic Agents/adverse effects , Doxycycline/therapeutic use , Stomatitis/chemically induced , Stomatitis/drug therapy , Adult , Antineoplastic Agents/therapeutic use , Double-Blind Method , Female , Humans , Leukemia/drug therapy , Male
11.
Oral Dis ; 23(7): 941-948, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28403570

ABSTRACT

OBJECTIVE: To assess changes in the salivary expression of IL-1α, IL-1ß, IL-2, IL-6, IL-10, IL-17, and TNF in acute leukemia (AL) patients before and during chemotherapy, and its association with HSV infection, oral candidiasis (OC), and oral mucositis (OM) onset. METHODS: Cohort study in AL patients >15 years starting induction chemotherapy at a Mexican oncological center (2013-2014). Onset of oral lesions (OLs) was assessed during follow-up, and saliva was obtained at baseline, at visit 2 (days 4-12), and at visit 3 (days 13-21) after chemotherapy, treated with a protease inhibitor and stored at -70°C. An enzyme-linked immunosorbent assay was performed. Cox proportional hazards regression models were constructed to estimate hazard ratios and its 95% CI (HR, 95% CI) for OL development. RESULTS: Forty-one patients were followed up, and 17 (41.5%) developed OLs. OL patients had higher baseline salivary IL-1α than those without lesions (p = 0.040). During visit 2, OL patients had higher levels of IL-1α (p = 0.033), IL-1ß (p = 0.016), IL-6 (p = 0.035), and TNF (p = 0.019) than those who did not develop OLs. Patients with HSV infection, OC, and OM showed higher salivary TNF levels during follow-up (HR: 3.52, 95% CI: 1.35-9.14, p = 0.010). CONCLUSION: AL patients undergoing chemotherapy with high salivary TNF levels were more likely to develop HSV infection, OC, and OM.


Subject(s)
Candidiasis, Oral/metabolism , Cytokines/metabolism , Herpes Simplex/metabolism , Saliva/metabolism , Stomatitis/metabolism , Adult , Antineoplastic Agents/adverse effects , Biomarkers/metabolism , Candidiasis, Oral/diagnosis , Doxycycline/adverse effects , Female , Herpes Simplex/diagnosis , Humans , Leukemia/drug therapy , Male , Randomized Controlled Trials as Topic , Stomatitis/diagnosis , Stomatitis/etiology , Tumor Necrosis Factor-alpha/metabolism , Young Adult
12.
Rev. med. vet. zoot ; 64(1): 32-43, ene.-abr. 2017. ilus, tab
Article in Spanish | LILACS | ID: biblio-902165

ABSTRACT

Los polimorfismos en el gen dopamina p-hidroxilasa (DBH) se asocian con el temperamento en los bovinos. En 16 animales de la raza criolla colombiana Blanco Orejinegro (BON), 20 Brahman (BRA) y 16 de Ganado de lidia (GLI), se evaluaron los polimorfismos del exón xii del gen DBH mediante secuenciación. Se encontraron 13 haplotipos, 6 en BON, 9 en BRA y 2 en GLI. El haplotipo H2 fue el más frecuente (0,615) y se encontró en las tres razas, mientras los haplotipos H6 y H9 fueron compartidos entre BON-BRA y BRA-GLI, respectivamente. La mayor diversidad genética (DG: 0,915 ± 0,04) y nucleotídica (DN: 0,011 ± 0,006) se encontró en la raza BRA, seguida por BON (DG: 0,700 ± 0,12; DN: 0,008 ± 0,004) y GLI (DG: 0,350 ± 0,14; DN: 0,0011 ± 0,001). Si bien el test de D-Tajima fue mayor que cero, no fue significativo (P > 0,05) en BON y BRA, pero en la raza GLI presentó un valor de -1,92 (P < 0,05). El análisis de varianza molecular mostró una variación entre las razas de 23,9% y una estructura poblacional (F^) de 0,23 (P < 0,001). Los mayores valores del coeficiente de coancestría se presentaron entre GLI y BRA (0,52) y entre GLI y BON (0,22). Se concluye que la raza GLI tiene baja diversidad en el gen DBH en comparación con las razas BON y BRA, que hay efectos de la selección natural en BON y BRA mientras que en la raza GLI se evidencia un barrido selectivo reciente y no a favor del temperamento.


Polymorphisms in the dopamine p-hydroxylase gene (DBH) have been associated with temperament in cattle. In 16 animals of Colombian creole breed Blanco Orejinegro (BON), 20 Brahman (BRA) and 16 fighting bulls (GLI), polymorphisms of exon xii of the DBH gene were evaluated by sequencing. 13 haplotypes were found, 6 in BON, 9 and 2 in BRA and GLI respectively. Haplotype H2 was the most frequent in the whole population (0,615) and it was found in all breeds. Haplotypes H6 and H9 were shared between BON-BRA and BRA-GLI, respectively. The greatest value of genetic (DG: 0.915 ± 0.04) and nucleotide (DN: 0.011 ± 0.006) diversity, was found in BRA, followed by BON (DG: 0.700 ± 0.12; DN: 0.008 ± 0.004) and GLI (DG: 0.350 ± 0.14; DN: 0.0011 ± 0.001). The D-Tajima test was greater than zero, but not significant (P > 0.05) in BON and BRA, GLI presented a value of -1.92 (P < 0.05). The analysis of molecular variance showed a variation between the breeds of 23.9% and a poblacional structure (F$t) of 0.23 (P < 0.001). The highest values of the coancestry coefficient were presented between GLI and BRA (0.52) and between GLI and BON (0.22). It is concluded that the GLI race has low diversity in the DBH gene compared to BON and BRA, that there are effects of neutral selection in BON and BRA breeds, whereas, in the GLI and not in favor of temperament.

13.
Opt Express ; 24(18): 20792-8, 2016 Sep 05.
Article in English | MEDLINE | ID: mdl-27607682

ABSTRACT

Integral microscopes (IMic) have been recently developed in order to capture the spatial and the angular information of 3D microscopic samples with a single exposure. Computational post-processing of this information permits to carry out a 3D reconstruction of the sample. By applying conventional algorithms, both depth and also view reconstructions are possible. However, the main drawback of IMic is that the resolution of the reconstructed images is low and axially heterogeneous. In this paper, we propose a new configuration of the IMic by placing the lens array not at the image plane, but at the pupil (or Fourier) plane of the microscope objective. With this novel system, the spatial resolution is increased by factor 1.4, and the depth of field is substantially enlarged. Our experiments show the feasibility of the proposed method.

15.
Oral Dis ; 22 Suppl 1: 149-57, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26882532

ABSTRACT

OBJECTIVES: To achieve a comprehensive understanding about the global burden of oral diseases in HIV-infected children and to identify research needs. MATERIALS AND METHODS: A literature search was conducted in PubMed (2009-2014) to address five questions: (i) prevalence of oral diseases in HIV-infected compared with uninfected children, (ii) impact of oral diseases on quality of life, (iii) effect of antiretroviral exposure in utero on craniofacial and dental development, (iv) important co-infections and antiretroviral complications, and (v) value of atraumatic restorative treatment. RESULTS: Studies showed a high prevalence of dental caries in HIV-infected children but the relationship between HIV infection and dental caries remains unclear. Also quality of life needs further investigation supported by better study designs and improvement of the instruments used. Up-to-date evidence suggested long-term harms associated with in utero antiretroviral exposure were minor but would require long-term follow-up through National Registries. The reviews also revealed the wide spectrum of metabolic disease due to antiretroviral therapy and co-infections such as tuberculosis. Finally, atraumatic restorative technique appears to be a simple and safe technique to treat dental caries but outcomes need further evaluation. CONCLUSIONS: The impact of antiretroviral therapy in HIV-infected children has raised novel challenging questions in the field of oral health warranting future research.


Subject(s)
Anti-Retroviral Agents/adverse effects , HIV Infections/epidemiology , Mouth Diseases/epidemiology , Prenatal Exposure Delayed Effects/chemically induced , Coinfection/epidemiology , Congresses as Topic , Craniofacial Abnormalities/chemically induced , Craniofacial Abnormalities/epidemiology , Dental Caries/epidemiology , Dental Caries/therapy , Female , Global Health , Humans , Lipodystrophy/chemically induced , Lipodystrophy/epidemiology , Pregnancy , Prevalence , Quality of Life , Tooth Abnormalities/chemically induced , Tooth Abnormalities/epidemiology , Tuberculosis/epidemiology
16.
J Microsc ; 261(3): 285-90, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26501512

ABSTRACT

Diabetes is currently the world's fastest growing chronic disease and it is caused by deficient production of insulin by the endocrine pancreas or by abnormal insulin action in peripheral tissues. This results in persistent hyperglycaemia that over time may produce chronic diabetic complications. Determination of glycated haemoglobin level is currently the gold standard method to evaluate and control sustained hyperglycaemia in diabetic people. This measurement is currently made by high-performance liquid chromatography, which is a complex chemical process that requires the extraction of blood from the antecubital vein. To reduce the complexity of that measurement, we propose a fully-optical technique that is based in the fact that there are changes in the optical properties of erythrocytes due to the presence of glucose-derived adducts in the haemoglobin molecule. To evaluate these changes, we propose to perform quantitative phase maps of erythrocytes by using telecentric digital holographic microscopy. Our experiments show that telecentric digital holographic microscopy allows detecting, almost in real time and from a single drop of blood, significant differences between erythrocytes of diabetic patients and healthy patients. Besides, our phase measurements are well correlated with the values of glycated haemoglobin and the blood glucose values.


Subject(s)
Blood Glucose/analysis , Diabetes Mellitus/diagnosis , Glycated Hemoglobin/analysis , Holography/methods , Mass Screening/methods , Microscopy/methods , Adult , Erythrocytes/physiology , Female , Humans , Male , Middle Aged , Young Adult
17.
Int J Oral Maxillofac Surg ; 44(4): 427-32, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25467736

ABSTRACT

In Mexico, there have been few studies on primary oral and sinonasal melanoma, an aggressive neoplasm with a low survival rate and few therapeutic alternatives. Further, there is limited information about its clinical and histopathological characteristics. The aim of this retrospective study was to describe the clinicopathological profile of these tumours in patients attending a major oncology reference centre in Mexico City over a 12-year period. Demographic and clinical data were obtained from the clinical charts, and histopathological features were evaluated. χ(2), Fisher's exact, and Mann-Whitney U-tests were used for analysis; significance was set at P<0.05. Thirty-three cases were studied (73% sinonasal melanoma (SNM) and 27% oral melanoma (OM)); 58% were female and the median age was 66 (Q1-Q3 55.5-75) years. Compared with OM patients, SNM patients had a shorter time to diagnosis (16.7 vs. 11.7 months, P=0.022), were identified at earlier stages (33.3% vs. 58.3%, P=0.010), and all presented symptoms (66.7% vs. 100%, P=0.015). All samples showed vertical growth and 96.9% exhibited pleomorphism. A higher proportion of cases with pleomorphism developed metastases at follow-up than those without (60% vs. 12.5%, P=0.026). The present study provides valuable information that could form the basis of future studies in the search for advanced therapy modalities.


Subject(s)
Melanoma/pathology , Mouth Neoplasms/pathology , Paranasal Sinus Neoplasms/pathology , Aged , Demography , Female , Humans , Immunohistochemistry , Male , Melanoma/epidemiology , Melanoma/therapy , Mexico/epidemiology , Middle Aged , Mouth Neoplasms/epidemiology , Mouth Neoplasms/therapy , Neoplasm Metastasis , Neoplasm Staging , Paranasal Sinus Neoplasms/epidemiology , Paranasal Sinus Neoplasms/therapy , Retrospective Studies
18.
Rev. Hosp. Clin. Univ. Chile ; 26(3): 185-197, 2015. tab, graf
Article in Spanish | LILACS | ID: lil-786571

ABSTRACT

Venous thromboembolic disease is the leading preventable cause of hospital mortality. Up to 75 percent of these are in non - surgical patients. This is a large, heterogeneous group of patients; so to know the risk factors for deep venous thrombosis crucial to provide a correct prevention. This article reviewed the indications, contraindications and complications of thromboprophylaxis. Difficult cases in elderly, obese, chronic kidney disease, critical care and cirrhotic patients were reviewed. The purpose of this article is to support decision – making on dvt prevention in hospitalized medical patients...


Subject(s)
Humans , Male , Female , Middle Aged , Aged, 80 and over , Anticoagulants/therapeutic use , Hospitalization , Venous Thromboembolism/complications , Venous Thromboembolism/prevention & control , Risk Factors
19.
Oper Dent ; 39(4): E160-70, 2014.
Article in English | MEDLINE | ID: mdl-24967990

ABSTRACT

SUMMARY The purpose of this study was to evaluate the influence the width of the occlusal isthmus and inlay material had on the stress distribution, displacement, and fracture resistance of upper human premolars. For this in vitro test, 35 intact upper premolars (UPM) were selected and five were kept intact for the control group (group I). The remaining 30 were divided into two experimental groups (n=15) according to the width of isthmus: conservative (CP) and extensive preparation (EP), one third and more than two thirds of cuspal distance, respectively. Five teeth from each experimental group were left without restoration for negative controls (CPnc and EPnc), and the remaining 10 in each group were subdivided according to the inlay material (resin or ceramic): group CPr, CP + indirect resin; group CPc, CP + ceramic; group EPr, EP + indirect resin; and group EPc, EP + ceramic. The cemented inlays were loaded in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed with stereomicroscopy, and the values of the fracture resistance evaluated by analysis of variance and Tukey test. For the finite element analyses, an average UPM for each group was modeled in Rhinoceros CAD software and imported to Ansys 13.0. An average of 320,000 tetrahedral elements and 540,000 nodes for the seven models were performed using the same experimental simulation setup for each. The models were constrained on the base, and a displacement of 0.02 mm was applied to keep a linear behavior for the analysis. A von Mises stress and total displacement fields were used for the coherence test and the maximum principal stress fields were used for mechanical behavior comparisons. Group I (161.73 ± 22.94) showed a significantly higher mean value than the other experimental groups (EPc: 103.55 ± 15.84; CPc: 94.38 ± 12.35; CPr: 90.31 ± 6.10; EPr: 65.42 ± 10.15; CPnc: 65.46 ± 5.37; EPnc: 58.08 ± 9.62). The stress distribution was different in all of the groups. EPnc showed a higher concentration of tensile stress on the cervical region of the proximal box. CPc and EPc provided a lower tensile stress and a smaller cuspal displacement. Within the limits of this study, the configuration of the inlay preparation is a significant factor in the fracture resistance of premolars: the smaller the amount of remaining tooth, the lower the fracture resistance. In addition, the teeth restored with ceramic materials showed a higher fracture resistance than those restored with composite resin.


Subject(s)
Bicuspid/injuries , Dental Stress Analysis , Elastic Modulus , Inlays , Tooth Fractures , Finite Element Analysis , Humans
20.
Oper Dent ; 2014 Feb 06.
Article in English | MEDLINE | ID: mdl-24502757

ABSTRACT

SUMMARY The purpose of this study was to evaluate the influence the width of the occlusal isthmus and inlay material had on the stress distribution, displacement, and fracture resistance of upper human premolars. For this in vitro test, 35 intact upper premolars (UPM) were selected and five were kept intact for the control group (group I). The remaining 30 were divided into two experimental groups (n=15) according to the width of isthmus: conservative (CP) and extensive preparation (EP), one third and more than two thirds of cuspal distance, respectively. Five teeth from each experimental group were left without restoration for negative controls (CPnc and EPnc), and the remaining 10 in each group were subdivided according to the inlay material (resin or ceramic): group CPr, CP + indirect resin; group CPc, CP + ceramic; group EPr, EP + indirect resin; and group EPc, EP + ceramic. The cemented inlays were loaded in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed with stereomicroscopy, and the values of the fracture resistance evaluated by analysis of variance and Tukey test. For the finite element analyses, an average UPM for each group was modeled in Rhinoceros CAD software and imported to Ansys 13.0. An average of 320,000 tetrahedral elements and 540,000 nodes for the seven models were performed using the same experimental simulation setup for each. The models were constrained on the base, and a displacement of 0.02 mm was applied to keep a linear behavior for the analysis. A von Mises stress and total displacement fields were used for the coherence test and the maximum principal stress fields were used for mechanical behavior comparisons. Group I (161.73 ± 22.94) showed a significantly higher mean value than the other experimental groups (EPc: 103.55 ± 15.84; CPc: 94.38 ± 12.35; CPr: 90.31 ± 6.10; EPr: 65.42 ± 10.15; CPnc: 65.46 ± 5.37; EPnc: 58.08 ± 9.62). The stress distribution was different in all of the groups. EPnc showed a higher concentration of tensile stress on the cervical region of the proximal box. CPc and EPc provided a lower tensile stress and a smaller cuspal displacement. Within the limits of this study, the configuration of the inlay preparation is a significant factor in the fracture resistance of premolars: the smaller the amount of remaining tooth, the lower the fracture resistance. In addition, the teeth restored with ceramic materials showed a higher fracture resistance than those restored with composite resin.

SELECTION OF CITATIONS
SEARCH DETAIL
...