Luis Vaz - Academia.edu (original) (raw)

Papers by Luis Vaz

Brazilian Dental Science, 2010

O propósito deste estudo foi avaliar “in vitro” a influência da ciclagem mecânica sobre a interfa... more O propósito deste estudo foi avaliar “in vitro” a influência da ciclagem mecânica sobre a interface infra-estrutura cerâmica e revestimento cerâmico. Os corpos de prova foram confeccionados de forma cilíndrica, contendo infra-estrutura com dimensões de 5mm de altura por 4mm de diâmetro, sendo a base com 5mm de diâmetro por 1mm de altura e corpo com 4mm de altura por 4mm de diâmetro. O revestimento cerâmico apresenta dimensões de 3 x 4mm. Foram confeccionados 10 corpos-de-prova, sendo 5mm correspondente ao grupo controle (sem ciclagem mecânica) e 5 submetidos à ciclagem mecânica, no sentido axial, com carga de 5N, freqüência de 20 Hz, durante 50.000 ciclos. Em seguida, ambos os grupos foram submetidos ao teste de cisalhamento na mesma na máquina (MTS – 810 Material Test System). O grupo controle e o grupo com ciclagem mecânica apresentaram valores médios de tensão de ruptura (Mpa) de 30.83 e 27,46, respectivamente, e foram submetidos ao teste t’student. Os autores concluíram que não ...

Ensaios e Ciência C Biológicas Agrárias e da Saúde

A liga Ti-6Al4V apresenta elementos nocivos ao organismo como alumínio e vanádio, demonstrando a ... more A liga Ti-6Al4V apresenta elementos nocivos ao organismo como alumínio e vanádio, demonstrando a importância do desenvolvimento de novas ligas de Ti, com adição de elementos não tóxicos. Para a realização deste estudo, os elementos foram fundidos a arco voltaico e usinados. As amostras foram divididas em grupos sem tratamento de superfície (Grupo I) e com modificação de superfície por irradiação de feixe de laser Yb:YVO4 em duas condições: 20Hz (Grupo II) e 35Hz (Grupo III). A caracterização estrutural e microestrutural foi realizada por avaliação de módulo de Young, microscopia eletrônica de varredura (MEV) com microanálise elementar por energia dispersiva de raios X (EDX) e a Difratometria de raios X (DRX). Os resultados demonstraram uma liga de estrutura predominantemente β e formação de uma camada de óxidos de titânio sobre a superfície da liga nas três condições estudadas, indicando uma proteção do material á reações químicas em relação ao meio ao qual se expõe (NaCl 0,9%). As ...

The International Journal of Oral & Maxillofacial Implants

T ooth loss is a common problem, not strictly, but highly prevalent, in the elderly population. 1... more T ooth loss is a common problem, not strictly, but highly prevalent, in the elderly population. 1,2 In general, long-term edentulous patients exhibit excessive alveolar bone resorption, which sometimes restricts the placement of dental implants, especially in the posterior area of the mandible. 3 It is noteworthy that such restrictions affect the definitive prosthesis design 4 and may result in long prosthetic cantilevers, 5 which are associated with higher amounts of stress transmitted to the prosthetic bar, prosthetic screws, abutments, and peri-implant bone. 6 The All-on-4 treatment concept (Nobel Biocare) introduced by Maló et al 7 enables the rehabilitation of severely resorbed arches with a complete fixed prosthesis connected to four dental implants. The rationale behind this concept is that by distally tilting the posterior implants at 30 or 45 degrees, bone-to-implant contact can be improved, reductions in the cantilever length can be achieved, and the oral rehabilitation can be performed with a minimum risk of causing injury in the inferior alveolar nerve. 8 Nevertheless, the presence of a minimum bone volume is of utmost importance to perform the All-on-4 treatment with dental implants of "sufficient" length (at least 10.0 mm). 7,8 Otherwise, complementary surgical procedures for vertical bone augmentation are priorly indicated. 9,10

Research, Society and Development, 2022

Titanium is a complex element and presents more than one crystallographic form, at room temperatu... more Titanium is a complex element and presents more than one crystallographic form, at room temperature it has a hexagonal crystal structure that transforms into a body-centered structure at 800ºC, and a melting point of 1670ºC ± 5ºC. Titanium alloys have superior mechanical properties to Ti c.p. in addition to excellent biocompatibility, a characteristic makes them the material of choice in orthopedic and dental applications. The alloy used in this study was the Ti-6Al-4V ELI alloy, obtained in cylindrical shape, sanded, and subsequently subjected to thermochemical treatment with NaOH. The physicochemical characterization was performed by the techniques of X-ray fluorescenic spectrometry (XRF), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and X-ray excited photoelectron spectroscopy (XPS). A biphasic structure (α and β) and the formation of an alkali titanate hydrogel (sodium titanate (Na2Ti5O11)) on the surface were observed, due to the reaction of the TiO2 film with...

Research, Society and Development, 2021

The objective of the present study was to evaluate the corrosion resistance of the experimental a... more The objective of the present study was to evaluate the corrosion resistance of the experimental alloy Ti-35Nb-7Zr-5Ta, modified by laser beam, in a physiological solution of 0.9% NaCl. This evaluation was carried out by open circuit potential analysis (EOCP), potentiodynamic polarization curves and cyclic polarization curves. The open circuit potential curves show the specimen irradiated by laser beam at 35 Hz presented a more stable and corrosion resistant surface. It was observed in the polarization curves, low current densities in the order of nA /cm2, for all specimen indicating an expected passive behavior for the investigated alloy. The cyclic polarization curves show that for specimen treated with laser, the potential for repassivation (Er) is greater in relation to the potential for corrosion (Ecorr), which indicates greater resistance to corrosion of metal alloys when treated with laser.

Brazilian Dental Journal, 2020

The aim of this study was to evaluate the effect of cleaning solutions on the retention force of ... more The aim of this study was to evaluate the effect of cleaning solutions on the retention force of o-ring-type overdenture attachments. The effect of four solutions on nitrile rings were evaluated: Cepacol (C), Cepacol with fluoride (CF), Listerine (L) and 0.05% sodium hypochlorite (SH); deionized water (DW) was used as a control. Matrices containing two implants and abutments and acrylic specimens with the metal capsules were obtained and divided into the groups. A simulation of 90 overnight immersions (8 h) was performed, and the tensile strength value was obtained at the beginning (T0) and in every 30 days (T1, T2 and T3) (n=6). In order to analyze o-ring surface damage after the immersions, a scanning electron microscopy (SEM) was used (n=1). For statistical analysis of the results, analysis of variance (ANOVA) and multiple comparisons with Bonferroni adjustment (test power=1.000; a=0.05) were used. There was a significant difference for the factors time (p<0.001), solution (p&...

Open Journal of Stomatology, 2020

The fixation stability achieved with the use of plates and screws in oral and maxillofacial surge... more The fixation stability achieved with the use of plates and screws in oral and maxillofacial surgery is a decisive factor in treatment success. The mechanical and structural properties of the internal fixation materials have direct influence on the dimensional stability and resistance of a fixation system, thus influencing treatment outcomes. This study proposed to analyze the dimensional and resistance patterns of titanium plates used for obtaining stable fixation in orthognathic surgery and craniofacial trauma. For this study, 30 conventional 2.0 mm straight four hole plates with bridge from three brands commercialized in Brazil, were subjected to macroscopic, microscopic, strength and hardness analysis. The dimensional measurements were performed using a digital caliper. Energy-dispersive X-ray spectroscopy analysis was performed by scanning electron microscopy to analyze the chemical composition of the samples. The mechanical resistance tests were performed with a universal testing machine. The samples were then submitted to Vickers hardness analysis, complying with the standards of ASTM E92. The data collected from the dimensional study was submitted to statistical analysis of the coefficient of variation, while the values obtained during the mechanical tests were analyzed by variance (ANOVA) and Tukey's test (p < 0.05). The sample groups presented different performances in resistance, hardness, size and surface, even though they were reported to be chemically similar compounds that allowed us to conclude the plates from Group 2 were more resistant than groups 1 and 3.

Materials Research, 2019

Extensive data reported the influence of the physicochemical properties on the bacterial adhesion... more Extensive data reported the influence of the physicochemical properties on the bacterial adhesion in biomaterials, of which surface roughness of titanium (Ti) can dictates methicillin-resistant Staphylococcus aureus (MRSA) adhesion to orthopedic implants. Herein, we investigated the influence of the Yb:YAG laser texturing of titanium-15molybdenum (TiMo-L) surface on the MRSA (ATCC #33591) cells adhesion and viability. The physicochemical properties and antibacterial performance of TiMo-L were compared to samples of laser-irradiated pure titanium (Ti-L). Polished samples (Ti-P and TiMo-P) were used as controls. Laser textured surfaces presented a high degree of hydrophilicity, an irregular-shaped cavity and a typical microstructured pattern, compared to the polished substrates. The laser irradiation reduced the peaks of molybdenum (Mo) in the surface of Ti-15Mo alloy, which is explained, at least in part, by the difference between the melting point of Ti (1.668 °C) and Mo (2.623 °C). Laser texturing raised the MRSA cells viability and statistically increased the bacterial adhesion to pure Ti (P < 0.01; Wilcoxon-Signed rank test) and Ti-15Mo alloy (P < 0.001; Paired t test). The TiMo-L surface was significantly less susceptible to MRSA cell adhesion compared to Ti-L substrate (P < 0.001; Paired t test).

Clinical implant dentistry and related research, Jan 30, 2018

Changes in the macrogeometry of dental implants are known to influence primary stability and the ... more Changes in the macrogeometry of dental implants are known to influence primary stability and the osseointegration process. The purpose of the present in vitro study was to evaluate the mechanical behavior of geometric changes in the apex region of dental implants. Thirty-five cylindrical dental implants (Titamax Ti; Neodent) were machined at the apical third to reproduce the experimental groups: without apical cut (Wc), apical bi-split cut, apical tri-split cut, apical quadri-split cut (Qs). One (control group) (Titamax Ti Ex) (n = 7) without any modifications was added. The implants had the same final dimensions (4.1 x 11 mm). All implants were inserted into artificial bone blocks and were evaluated by insertion torque and resonance frequency by ISQ values (Osstell). Two-tailed analysis of variance (One-way ANOVA) and Tukey's post-test (P < .05). Control and Qs implants showed a significant increase of the insertion torque (P < .001). For the resonance frequency, Wc and (...

Dental press journal of orthodontics, 2017

The aim of this paper was to determine the amount of deformation in four commercial brands of nic... more The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test. Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture. Most subgroups were sim...

Revista Estomatológica Herediana, 2016

El objetivo de esta revisión, fue describir de una manera sencilla las principales característica... more El objetivo de esta revisión, fue describir de una manera sencilla las principales características de la Fibrina Rica en Plaquetas (FRP), su composición, propiedades y aplicación clínica. La FRP, biomaterial autógeno y concen- trado plaquetario de segunda generación, es una matriz de fibrina que contiene leucocitos, plaquetas y factores de crecimiento, que son necesarios para los procesos de cicatrización, lo que brinda a este biomaterial, una gran utilidad en diversas áreas de la salud, incluyendo la odontología. Con esta revisión concluimos que la FRP es una alternativa real para mejorar la cicatrización de procedimientos quirúrgicos y potenciar otros biomateriales regenerativos en diversas áreas de la odontología, además de su accesibilidad y bajo costo.

$Research paper thumbnail of Influencia de un medio fluorado en la fractura de dos combinaciones de conjunto implante / cabezal de Ti Cp$

Revista Estomatológica Herediana, 2014

El objetivo de este trabajo fue evaluar la influencia de un medio fluorado en la fractura delconj... more El objetivo de este trabajo fue evaluar la influencia de un medio fluorado en la fractura delconjunto implante/pilar en sistemas de hexágono interno y hexágono externo. La fractura fueproducida por fatiga de bajo ciclo, analizándose la superficie mediante microscopía electrónicade barrido (MEB). Se simularon cinco años de uso regular de productos de higiene oral conteniendo1.500 ppm de NaF, pH 6,8. Este contacto prolongado con fluoruros influenció negativamenteel desempeño a la fatiga de bajo ciclo realizada en una máquina de ensayos mecánicos MTS-810programada a 100.000 ciclos, 15 Hz, con 30% y 60% de valores de stress máximos en traccióny compresión no axial, respectivamente. El análisis a través del MEB reveló signos de corrosiónsuperficial del titanio en el grupo test. Se concluyó que el contacto prolongado con fluoruroafecta el desempeño mecánico y puede contribuir a desarrollar fracturas, cuando se producencondiciones de sobrecarga sobre estructuras de titanio, lo cual puede d...

Journal of Applied Oral Science, 2015

D ental composites cured at high temperatures show improved properties and higher degrees of conv... more D ental composites cured at high temperatures show improved properties and higher degrees of conversion; however, there is no information available about the effect of pre-heating on material degradation. Objectives: This study evaluated the effect of preheating on the degradation of composites, based on the analysis of radiopacity and silver penetration using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Material and Methods: Thirty specimens were fabricated using a metallic matri (mm) and the composites Dura ll S (eraeus ul er),-(M/ESPE), and Z-350 (3M/ESPE), cured at 25°C (no pre-heating) or 60°C (pre-heating). Specimens were stored sequentially in the following solutions: 1) water for 7 days (60°C), plus 0.1 N sodium hydroxide (NaOH) for 14 days (60°C); 2) 50% silver nitrate (AgNO 3) for 10 days (60°C). Specimens were radiographed at baseline and after each storage time, and the images were evaluated in gray scale. After the storage protocol, samples were analyzed using SEM/EDS to check the depth of silver penetration. Radiopacity and silver penetration data were analyzed using ANOVA and Tukey's tests (=5%). Results: Radiopacity levels were as follows: Dura ll VS Z-350 Z-250 (p 0.05). The depth of silver penetration into the composites ranked as follows: Dura ll VS Z-350 Z-250 (p 0.05). After storage in water/ NaOH, pre-heated specimens presented higher radiopacity values than non-pre-heated specimens (p<0.05). There was a lower penetration of silver in pre-heated specimens (p<0.05). Conclusions: Pre-heating at 60°C mitigated the degradation of composites based on analysis of radiopacity and silver penetration depth.

Revista da Faculdade de Odontologia - UPF, Mar 9, 2010

The Journal of Contemporary Dental Practice, 2015

Aim This study evaluated the effect of ultrasonic vibration on the tensile strength required to r... more Aim This study evaluated the effect of ultrasonic vibration on the tensile strength required to remove intraradicular post cemented with different materials. Materials and methods Bovine teeth were selected, and 7 mm of the cervical root canals were prepared to size 5 Largo drill, the posts were cemented with zinc phosphate, Enforce (resin) or Rely X (glass ionomer). The specimens were divided into six groups (n = 10), according to the following procedures: GI—cementation with zinc phosphate associated with traction force; GII—cementation with zinc phosphate associated with ultrasonic activation and traction force; GIII—cementation with Enforce associated with traction force; GIV—cementation with Enforce associated with ultrasonic activation and traction force; GV—cementation with Rely X associated with traction force; and GVI—cementation with Rely X associated with ultrasonic activation and traction force. The tensile test was conducted using the electromechanical testing machine, ...

Este trabalho teve como proposta analisar quantitativamente o conteúdo de fluoretos nos alginatos... more Este trabalho teve como proposta analisar quantitativamente o conteúdo de fluoretos nos alginatos para uso odontológico e a liberação de fluoretos de moldes desses alginatos em água milliQ, saliva artificial e ácido clorídrico 0,1 mol/l. Foram investigadas sete marcas de alginatos disponíveis comercialmente no Brasil, sendo analisados dois lotes de cada material. As concentrações de fluoretos nas diferentes amostras foram determinadas por potenciometria direta, utilizando o eletrodo seletivo combinado de fluoreto. Os materiais que apresentaram maiores concentrações médias de fluoreto total foram Hydrogum (7052,87µg/g), Jeltrate Plus (6519,68µg/g) e Orthoprint (6218,18µg/g). Apenas os materiais das marcas Hydrogum e Jeltrate apresentaram diferenças nas concentrações de fluoretos entre os lotes um e dois. Os materiais apresentaram diferenças na liberação de fluoretos dos moldes, cujas maiores concentrações médias foram liberadas pelas marcas Hydrogum e Orthoprint. O meio influenciou n...

PURPOSE: This study evaluated the flow rate of the Acroseal, AH Plus, Endomethasone N, Sealapex, ... more PURPOSE: This study evaluated the flow rate of the Acroseal, AH Plus, Endomethasone N, Sealapex, and ActiV GP according to the standards of the ISO specification 6876/2001. METHODS: A volume of 0.05 mL of the cement mixed according to the manufacturer's recommendations was placed on a glass plate. At 180±5 s after the commencement of mixing, the second glass plate was placed on top of the sealer, followed by the weight of mass approximately 100 g to make a total mass on the plate of 120±2 g. Ten min after the start of mixing, the weight was removed and the value of the diameter of the compressed disc of sealer was measured. The mean of three such determinations for each sealer was taken as the flow of the material. The mean values were compared using ANOVA and Tukey's tests. RESULTS: The results obtained were: Acroseal 21.24 mm, AH Plus 22.72 mm, ActiV GP 24.90 mm, Endomethasone N 18.76 mm, and Sealapex 25.15 mm. CONCLUSION: Only the Endomethasone N did not conform to ISO Sp...

The Journal of Indian Prosthodontic Society, 2007

This study aimed to evaluate the tensile bond strength of adhesive systems in abraded enamel and ... more This study aimed to evaluate the tensile bond strength of adhesive systems in abraded enamel and deep dentin of the occlusal surface of forty human molar teeth. Enamel surfaces as well as the rest of the teeth were coated with epoxy resin and regularized and polished with silicon carbide sandpapers. The 40 teeth were randomized into eight groups of fi ve teeth per group. Four groups were assigned to have deep dentin as the dental substrate and the other four had abraded enamel as the substrate for the adhesives to be tested. The adhesives being tested were the total etching Single Bond: SB, the selfetching Clearfi l SE bond: CSEB, self-etching One Up Bond F: OUBF and the self-etching Self-Etch Bond: SEB adhesives. The samples (teeth) were restored with composite resin and subjected to a traction assay. The results were statistically analyzed using the ANOVA and TUKEY tests. The total etching SB adhesive system had the greatest bonding strength of all the adhesives tested, on both dental substrates (20.1 MegaPascals (MPa) on abraded enamel and 19.4 MPa on deep dentin). Of the self-etching dental adhesives tested, CSEB had the greatest bonding strength on both substrates (14.6 MPa on abraded enamel and 15.4 MPa on deep dentin). Both OUBF (11.0 MPa for enamel, 13.1 MPa for dentin) and SEB (10.2 MPa for enamel, 12.6 MPa for dentin) showed comparable bonding strengths without any signifi cant differences for either substrate Thus, the total etching SB adhesive system had better bonding strength than the other self-etching adhesives used, regardless of the dental substrate to which the adhesives had been bonded.

O objetivo dessa revisão foi relatar uma visão geral e descritiva a respeito das propriedades de ... more O objetivo dessa revisão foi relatar uma visão geral e descritiva a respeito das propriedades de duas soluções irrigadoras, a solução de hipoclorito de sódio e de clorexidina com diferentes concentrações, utilizadas no tratamento de canais radiculares. Uma solução irrigadora considerada ideal deve apresentar ação antimicrobiana, dissolver resíduos teciduais, promover molhamento com finalidade de facilitar a instrumentação, e apresentar biocompatibilidade com os tecidos adjacentes. O hipoclorito de sódio utilizado em diferentes concentrações para limpeza de canais radiculares tem sido a solução de escolha entre os profissionais por apresentar ação antimicrobiana e atuar como solvente tecidual. Porém, atualmente, a clorexidina vem sendo muito utilizada como solução irrigadora devido a propriedades específicas que viabilizam sua utilização, tais como substantividade, efetividade antimicrobiana, e baixa toxicidade. Desse modo concluí-se que a solução de clorexidina com diferentes concentrações se apresenta como uma possível alternativa de solução irrigadora para o tratamento de canais radiculares. Termos de indexação: Clorexidina. Hipoclorito de sódio. Irrigantes do canal radicular.