Efecto de fuentes de polimerización sobre el sellado marginal de restauraciones de resinas de incremento único / Effect of polymerization sources on the marginal sealing of single-increment resin restorations

Introducción: Las resinas de incremento único permiten una fotoactivación de 4 a 5 mm de profundidad, reduciendo el tiempo clínico de aplicación. No obstante, se deben considerar factores como la contracción que puede afectar el sellado marginal de la restauración. Objetivo: Evaluar el efecto de tres fuentes de polimerización sobre el sellado marginal de restauraciones Clase II, realizadas con tres sistemas de resina de incremento único. Métodos: Se realizó un estudio experimental in vitro. El cálculo de la cantidad de unidades de estudio se realizó con el software EPIDAT, para lo cual se tomaron las medias de dos estudios previos. Se realizaron nueve subgrupos según el material de restauración y la fuente de polimerización. En cada diente se confeccionaron dos restauraciones Clase II, que fueron realizadas según las instrucciones del fabricante. Los dientes fueron sometidos a inmersión pasiva en azul de metileno al 1 por ciento por 24 h. Los dientes fueron seccionados mesiodistalmente. Se realizaron fotografías con una cámara Canon y un lente macro 100 mm. La filtración marginal fue medida según una escala del 0 al 4. Los datos fueron analizados con las pruebas de Kruskal-Wallis para la comparación de los grupos. Se estableció un nivel de significancia ajustado al 5 por ciento. Resultados: La resina con menor nivel de filtración fue Filtek Bulkfill, con un 53,3 por ciento correspondiente a la escala 0, mientras que la resina con una mayor filtración fue Tetric N-Ceram Bulk Fill con un 76,7 por ciento (escala 4), similar a Sonicfill (70,0 por ciento). Conclusiones: Las diferentes fuentes de polimerización no influenciaron el nivel de filtración entre los tres sistemas de resinas de incremento único. Filtek Bulkfill presentó un mejor sellado marginal al compararlo con SonicFill y Tetric N-Ceram Bulk Fill(AU)

Introduction: Single-increment resins allow a photoactivation of 4 to 5 mm deep, reducing the clinical time of application. However, factors such as shrinkage that may affect the marginal sealing of the restoration should be considered. Objective: Evaluate the effect of three polymerization sources on the marginal sealing of Class II restorations, carried out with three single-increment resin systems. Methods: An in vitro experimental study was conducted. The calculation of the number of study units was carried out with the EPIDAT software, for which the means of two previous studies were taken. Nine subgroups were made according to the restoration material and the polymerization source. Two Class II restorations were made on each tooth, which were carried out according to the manufacturer's instructions. The teeth were subjected to passive immersion in 1 percent methylene blue for 24h. The teeth were sectioned mesiodistally. Photographs were taken with a Canon camera and a 100mm macro lens. Marginal filtration was measured on a scale of 0 to 4. Data were analyzed with Kruskal-Wallis tests for group comparison. A significance level adjusted to 5 percent was established. Results: The resin with the lowest filtration level was Filtek Bulkfill, with 53.3 percent corresponding to scale 0, while the resin with the highest filtration was Tetric N-Ceram Bulk Fill with 76.7 percent (scale 4), similar to Sonicfill (70.0 percent). Conclusions: The different polymerization sources did not influence the level of filtration between the three single-increment resin systems. Filtek Bulkfill presented a better marginal seal when compared to SonicFill and Tetric N-Ceram Bulk Fill(AU)

Allergic Reactions in Orthodontic Patients: A Review

ABSTRACT: Allergic reactions are host immune responses to endogenous or exogenous antigens, which can result in local and systemic problems. Among the main allergens are the dental materials used in orthodontics, which faces some challenges with regard to biocompatibility with oral tissues.This study aimed to analyze in the literature which materials used in orthodontics are related to the appearance of oral and perioral allergic reactions, as well as to investigate the most prevalen t manifestations.An integrative review was carried out with articles published between 2010 and 2020 on the PubMed, Embase, and ScienceDirect on-line database. For this, MeSH descriptors and synonyms were used following two semantic fields: "Hypersensitivity" in association with "Orthodontic Appliances", the selection of studies counted with the stages of identifica tion, screening, eligibility and inclusion. Randomized clinical trials, cross-sectional or cohort clinical trials; Patients with alle rgic reactions affecting the oral or perioral region due to contact with orthodontic material, were included in the review.From a to tal of 549 articles only 04 were selected for the study. In accordance with what has been analyzed in the evidence of these studies, periodontal changes such as gingival inflammation as well as erythema, edema, papules and blisters were the main reactions described. Furthermore, in all articles there was an association with nickel and in only one with chromium. It is possible to i nfer that inflammatory lesions are frequent manifestations on the use of nickel in orthodontic patients.

RESUMEN: Las reacciones alérgicas son respuestas inmunes del huésped a antígenos endógenos o exógenos, los cuales pueden provocar problemas locales y sistémicos. Entre los principales alérgenos se encuentran los materiales dentales utilizados en la ortodoncia, la cual se enfrenta a algunos desafíos respecto a la biocompatibilidad de los tejidos orales. Este estudio tuvo como objetivo analizar en la literatura que materiales utilizados en ortodoncia están relacionados con la aparición de reacciones alérgicas orales y periorales, así como investigar las manifestaciones más prevalentes. Se llevó a cabo una revisión con artículos publicados entre 2010 y 2020 en las bases de datos PubMed, Embase y ScienceDirect. Para ello, se utilizaron descriptores y sinónimos de MeSH siguiendo dos campos semánticos: "Hipersensibilidad" en asociación con "Aparatos de Ortodoncia", la selección de estudios contó con las etapas de identificación, cribado, elegibilidad e inclusión. Ensayos clínicos aleatorizados, ensayos clínicos transversales o de cohortes; en la revisión se incluyeron pacientes con reacciones alérgicas que afectaron a la regiones oral o perioral debido al contacto con material de ortodoncia. De un total de 549 artículos sólo cuatro fueron seleccionados para el estudio. De acuerdo con lo que se analizó en la evidencia, las principales reacciones descritas fueron cambios periodontales, como inflamación gingival, eritema, edema, pápulas y ampollas. Además, en todos los artículos hubo una asociación con níquel y solamente en uno con cromo. Es posible inferir que las lesiones inflamatorias son manifestaciones frecuentes sobre el uso de níquel en pacientes de ortodoncia.

Synthesis, characterization, and incorporation of upconverting nanoparticles into a dental adhesive

Abstract: The purpose of this study was to describe the synthesis, characterization, and functionalization of b-NaYF4:30%Yb/0.5%Tm upconverting nanocrystals for use as nanofillers in a dental adhesive and microscopically evaluate the interface between the particles and a commercial adhesive. The upconverting nanoparticles were synthesized and purified by thermal decomposition, and their chemical composition determined by energy dispersive X-Ray spectroscopy. The crystalline structure was characterized using X-Ray diffraction and morphology and size were observed with scanning and transmission electron microscopy. Upconverting emission was evaluated by spectrophotometry irradiating the particles with a 975 nm diode laser. Particles were functionalized with polyacrylic acid and the success was confirmed by measurement of Zeta Potential and transmission electron microscopy. The results of X-ray diffraction found a pure hexagonal phase crystalline pattern. Scanning electron microscopy showed uniform dispersion of hexagonal-shaped particles of approximately 150 nm. Upconversion emission was observed in 344 nm, 361 nm, 450 nm, 474nm, 646 nm, 803 nm. Functionalization success was confirmed by formation of a stable aqueous colloid with a Zeta potential of −29.5mV and the absence of voids in the particle-adhesive interface on the transmission electron microscopy images. The reported synthesis and functionalization process produced upconverting nanoparticles emitting photons within the blue spectral region (450 nm and 474 nm).

Tara Gum as a Controlled Delivery System of Fluoride in Toothpaste: In Vitro Enamel Remineralization Study

ABSTRACT Objective: To evaluate the remineralizing potential of a hydrocolloid-based, controlled fluoride-releasing system added to dentifrice formulas. Material and Methods: Sixty-five human enamel blocks were prepared and the surface microhardness (SH0) values were determined. The artificial caries lesions were induced and the demineralization surface microhardness (SH1) was evaluated. The blocks were randomly allocated into five groups (n = 13): (1) 100-TGF (100% NaF with Tara gum added); (2) 50-TGF (50% free NaF + 50% NaF with Tara gum added); (3) 100% TG (100% Tara gum without fluoride); (4) 100% NaF (positive control); and (5) placebo (without Tara gum and NaF). The blocks were submitted to 7 days pH cycling and treated with dentifrice slurries twice a day. Finally, surface hardness (SH2) was assessed and the percentage of surface hardness recovery (%SMHR) was calculated. Analysis of variance (ANOVA) followed by Bonferroni test was used for statistical analysis. Results: A positive %SMHR was found in the 100% NaF (5.07) and 50-TGF (0.64) groups, while the 100-TGF (-1.38), 100% TG (-3.88) and placebo (-0.52) did not undergo remineralization. Statistically significant differences were observed between 100% NaF and all the groups except for 50-TGF (p<0.05). Conclusion: The presence of hydrocolloid (Tara gum) promoted minimal remineralization when associated with NaF. In the applied model, Tara gum may have compromised remineralization, preventing free fluoride from acting effectively in the carious lesion.

Effect of Listerine Mouthwash with Green Tea on the Inhibition of Streptococcus Mutans: A Microbiologic Study

Abstract Objective: To evaluate in vitro the antimicrobial effect of Listerine-green tea mouthwash on Streptococcus mutans (SM) in comparison with 0.12% Chlorhexidine (CHX) and Listerine-Zero. Material and Methods: The sensitivity and growth inhibition of SM bacterial species were evaluated and compared between Listerine-green tea, 0.12% CHX and Listerine-Zero mouthwashes. Sixty plates containing SM colonies were prepared in three groups (n=20), and growth inhibition zones were measured using the disk diffusion agar test in mm. Data were analyzed with SPSS 21. One-way ANOVA was used to compare the efficacy of the three mouthwashes tested. Post hoc Tukey tests were used for two-by-two comparisons. Statistical significance was defined at P<0.05. Results: Analysis of data showed significant differences between the three groups (p<0.001); 0.12% CHX was the most effective mouthwash, and Listerine-Zero exhibited the least effect on the growth inhibition of SM (p<0.004). Conclusion: All three mouthwashes were significantly effective in inhibiting the growth of SM. The effect of Listerine-green tea mouthwash was higher than that of Listerine-Zero and less than that of 0.12% CHX.

Influence of activation mode, fatigue, and ceramic interposition on resin cements' diametral tensile strength

Abstract This study evaluated the influence of activation modes, on Diametral Tensile Strength (DTS) of dual cured resin cements subjected to a Mechanical Fatigue test (MF). Four dual-cured resin cements (RelyX UNICEM [U], RelyX ARC [A], ENFORCE [E] and Nexus 2 [N]) were activated by three different curing modes as follows: Self-Curing (SC), Dual Cure activation with photoactivation executed directly (DC) and Dual Cure activation with Photoactivation Through Porcelain (DCTP). After 24 hours, half of the sample was subjected to 30.000 fatigue cycles at 1 Hz frequency and 12 N load. Then, all specimens were subjected to DTS test in Instron Universal Testing Machine and data were analyzed by three-way ANOVA and Tukey's Test (5%). The results of DTS test means (MPa) and standard deviation, for each cement factor activated by SC, DC and DCTP was respectively: U (28.12 ± 5.29; 37.44 ± 6.49 and 40.10 ± 4.39), A (49.68 ± 8.42; 55.12 ± 5.16 and 63.43 ± 6.92), E (49.12 ± 3.89; 56.42 ± 8.88 and 56.96 ± 6.45) and N (61.89 ± 11.21; 59.26 ± 9.47 and 62.56 ± 10.93). Turkey's test indicated that DC is related to the highest DTS values; Nexus 2 DTS remained the same independently of activation mode and that the Porcelain disk interposition enhanced DTS only for RelyX ARC the ANOVA statistical test indicated that MF didn't alter the DTS values for all experimental groups. MF results clinical implication is that all cements tested exhibited, in an immediate loading, good cross linked bonds quality.

Can low-fusing glass application affect the marginal misfit and bond strength of Y-TZP crowns?

Abstract To evaluate the effect of different surface treatments on the marginal misfit and retentive strength between Y-TZP crowns and an epoxy resin. Forty (40) epoxy resin (G10) abutments (height: 5mm, conicity: 60, finish line: large chamfer) with equal dimensions were milled and included in polyurethane to simulate the periodontal ligament. Next, 40 Y-TZP crowns (thickness: 1mm) were milled (Cerec in Lab) and randomly divided into four groups (n=10) according to the surface treatment: GS(glaze spray), GP(glaze powder/liquid), P(zirconia primer) and RS(tribochemical silica coating). The conditioned surfaces were cemented with dual self-adhesive cement, light cured and submitted to thermomechanical cycling (2x106, 100N, 4Hz, 5°/55°C). Marginal misfit was analyzed by a stereomicroscope and SEM. Retentive strength test was performed (1mm/min) until crown debonding. Glaze layer thickness was also performed to GS and GP groups. Marginal misfit data were analyzed by Kruskal Wallis and Dunn tests; one-way ANOVA and Tukey (5%) analyzed the tensile strength data. The marginal misfit of the GS (48.6±19.9μm) and GP (65.4±42.5μm) were statistically lower than the RS (96±62.9μm) and P (156±113.3μm) (p=0.001). The retentive strength of the GP (470.5±104.1N) and GS (416.8±170.2N) were similar to the P (342.1±109.7N), but statistically higher than those of the RS (208.9±110N). The GS and GP glaze layer was 11.64μm and 9.73μm respectively. Thus, glaze application promoted lower marginal discrepancy and higher retentive strength values than conventional techniques.

Accuracy of various imaging methods for detecting misfit at the tooth-restoration interface in posterior teeth

PURPOSE: The present study aimed to evaluate which of the following imaging methods best assessed misfit at the tooth-restoration interface: (1) bitewing radiographs, both conventional and digital, performed using a photostimulable phosphor plate (PSP) and a charge-coupled device (CCD) system; (2) panoramic radiographs, both conventional and digital; and (3) cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Forty healthy human molars with class I cavities were selected and divided into 4 groups according to the restoration that was applied: composite resin, composite resin with liner material to simulate misfit, dental amalgam, and dental amalgam with liner material to simulate misfit. Radiography and tomography were performed using the various imaging methods, and the resulting images were analyzed by 2 calibrated radiologists. The true presence or absence of misfit corresponding to an area of radiolucency in regions subjacent to the esthetic and metal restorations was validated with microscopy. The data were analyzed using a receiver operating characteristic (ROC) curve, and the scores were compared using the Cohen kappa coefficient. RESULTS: For bitewing images, the digital systems (CCD and PSP) showed a higher area under the ROC curve (AUROC) for the evaluation of resin restorations, while the conventional images exhibited a larger AUROC for the evaluation of amalgam restorations. Conventional and digital panoramic radiographs did not yield good results for the evaluation of resin and amalgam restorations (P .05), but showed no discriminatory ability for amalgam restorations (P < .05). CONCLUSION: Bitewing radiographs (conventional or digital) should be the method of choice when assessing dental restoration misfit.

Avaliação da redução das forças geradas por elásticos ortodônticos em cadeia / Evaluation of the forces reduction delivered by orthodontic elastomeric chain

A movimentação dentária é obtida através de recursos capazes de gerar forças e o ortodontista dispõe de uma série de dispositivos mecânicos responsáveis por realizar essa movimentação, incluindo os elásticos em cadeia, que além de serem de fácil aplicação, são também bem tolerados pela maioria dos pacientes. Porém, apesar dos avanços obtidos no desenvolvimento destes materiais, ainda existem dúvidas em relação a influência de diversos fatores que podem afetar a liberação de forças destes. O objetivo deste trabalho é avaliar a redução dos valores das forças geradas por elásticos ortodônticos em cadeia em relação a intensidade de estiramento, tempo e configuração. Foram utilizados 432 segmentos de cadeias elásticas, divididos em 3 grupos de acordo com as configurações curta, média e longa. Os segmentos de cadeia foram distendidos em 25%, 50%, 75% e 100% do comprimento original e mantidos estirados em placas de acrílicos confeccionadas especialmente para esse fim, em água destilada, a temperatura constante de 37°C durante os períodos de 24 horas, 1, 2, 3 e 4 semanas. Os dados foram avaliados através do teste de Análise de Variância (ANOVA) seguido do teste de Tukey. Todos os fatores mostraram significância estatística na diminuição das forças geradas. Quanto maior a intensidade de estiramento e tempo, maior a redução dos valores das forças geradas, entretanto os estiramentos 75% e 100% quando comparados entre si não apresentaram significância estatística. As cadeias elásticas do tipo curto foram capazes de promover a menor redução dos valores das forças geradas.

The aim of this study is to evaluate the reduction in the values of the forces generated by orthodontic chain regarding the intensity of stretching, time and configuration. Were used 432 segments of elastic chains, divided into 3 groups according to following configurations: short, medium and long. The chain segments were stretched at 25%, 50%, 75% and 100% and kept stretched in acrylic plates confectioned specially for this purpose, in distilled water, at constant temperature of 37°C, during periods of 0h, 24h, 1, 2, 3 and 4 weeks. The data were evaluated by analysis of variance (ANOVA) followed by Tukey test. All factors showed statistical significance in the reduction of forces delivered. The higher the stretching intensity and the time, the greater the reduction of the forces generated values. However the stretches of 75% and 100% when compared to each other were not statistically significant. The short elastomeric chain were able to promote the smallest reduction of the values of forces generated

The challenges: Stent materials from the perspective of the manufacturer

The article presents an overview of the basic data influencing the choice of materials for the manufacture of self-expanding metallic stents to be implanted into gastrointestinal tract, particularly esophageal stents. The data are evaluated primarily in terms of the manufacturer of stents. The text emphasizes not only the importance of the materials themselves, but also the biological environment in which the stent is used. Brief history of materials used in gastrointestinal stents mentions stainless steel, cobalt-chromium and nickel titanium alloys and polymers (polyester and polydioxanone). The text describes the properties of metal materials (composition, corrosion, mechanical properties) with particular focus on nickel-titanium alloy—nitinol. It lists advantages and disadvantages of nitinol. At the end of the review the authors briefly present their opinion on future materials of gastrointestinal stents and their covering.

Avaliação do comportamento mecânico e da microestrutura de duas marcas comerciais de zircônia monolítica 3Y-TZP sob influência de diferentes parâmetros de sinterização / Microstructural and mechanical evaluation of two commercial monolithic 3YTZP zirconia under various sintering conditions

Cerâmicas a base de zircônia para coroas e próteses fixas monolíticas prometem suprimir a vulnerabilidade ao lascamento de restaurações de múltiplas camadas, proporcionando estética e resistência mecânica simultâneas. No entanto, é possível que as alterações realizadas para maximizar suas propriedades óticas possam afetar a resistência mecânica. O presente estudo teve por objetivo comparar, com base na microestrutura, o comportamento mecânico de duas marcas comerciais de zircônias monolíticas a uma zircônia convencional para infraestruturas, observando ao mesmo tempo algumas variações nos parâmetros de sinterização. As zircônias monolíticas ceramill Zolid e Prettau e a zircônia convencional IPS e.max ZirCAD foram sinterizadas sob a temperatura preconizada pelos respectivos fabricantes, formando os grupos Z1450, P1600 e I1530. Adicionalmente, foram criados os grupos Z1530 e Z1600, representados pela zircônia ceramill Zolid submetida a ciclos modificados. Foram confeccionados 13 corpos de prova para cada grupo, os quais foram submetidos aos ensaios de difração de raios-x, densidade, análise do tamanho médio de grão e resistência à flexão em 4 pontos. Os espectros de difração revelaram a presença da fase tetragonal metaestável em todos os grupos antes e após a sinterização. Quanto à densidade, apresentou-se superior a 99% apenas nos grupos formados pelas zircônias Prettau e IPS e.max ZirCAD. O tamanho médio dos grãos permaneceu abaixo de 1m em todas as situações, sendo maior para o grupo P1600 (0,814m) e menor para o grupo Z1450 (0,463m). Embora tenha sido observada uma tendência de melhoria nos resultados sob taxa de aquecimento mais lenta, os grupos formados pela zircônia monolíticas ceramill Zolid obtiveram os valores mais baixos de confiabilidade (m=4,58 para Z1530) e de resistência mecânica (621,01±138,08MPa para Z1450). A zircônia Prettau apresentou valores de resistência mecânica mais altos e homogêneos (864,18±118,21MPa), contudo inferiores aos da...

Monolithic zirconia ceramics for crown and bridge applications were designed to eliminate chipping trends of bilayered restorations, providing both aesthetic and mechanical strength. Nonetheless, it has been suggested that improvements in optical properties may affect the mechanical strength of these materials. The present study aimed to compare, based on a microstructural analysis, the mechanical behavior of two commercial monolithic zirconia ceramics with a conventional core zirconia material, as well as to verify sintering parameters modifications. Two monolithic zirconia ceramics (Ceramill Zolid and Prettau) and a conventional core zirconia material (IPS e.max ZirCAD) were sintered according to manufacturer´s recommendations, forming groups Z1450, P1600 and I1530. Extra groups, Z1530 and Z1600, were originated from ceramill Zolid zirconia specimens subjected to modified sintering cycles. The thirteen specimens that were manufactured for each group were submitted to x-ray diffraction analysis, density, average grain size determination and 4-point-bending tests. X-ray diffraction analysis revealed the presence of tetragonal metastable phase in all groups before and after sintering. Relative density found for Prettau and IPS e.max ZirCAD were greater than 99%. The average grain size remained below 1m for all groups. P1600 showed the largest grain sizes (0,814m) while Z1450 (0,463m) demonstrated the smallest ones. Groups originated from ceramill Zolid also presented the lowest Weibull modulus (m=4,58 for Z1530) and flexural strength results (621,01±138,08MPa for Z1450), regardless of non significant improvements that were achieved when using a low heating rate protocol. Prettau zirconia showed better mechanical behaviour and a more homogeneous distribution of results (864,18±118,21MPa), although lower than those of IPS e.max ZirCAD zirconia (1057,41±150,54MPa). Findings from this study show that the two commercial monolithic zircônia...

In vitro evaluation of force degradation of elastomeric chains used in Orthodontics

OBJECTIVE: To analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics. METHODS: The sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation force was recorded at the following time intervals: initial, 1, 3, 5, 7 and 9 hours, and 1, 7, 14, 21, 28, and 35 days. RESULTS: There was a statistically significant difference between the groups regarding the force degradation, mainly within the first day, as a force loss of 50-55% was observed during that time in relation to the initial force. The force delivered at 35 days ranged from 122 g to 148 g. CONCLUSION: All groups showed force degradation over time, regardless of their trademarks, a force loss of 59-69% was observed in the first hour compared to baseline. However, because the variation in force degradation depends on the trademark, studies such as the present one are important for guiding the clinical use of these materials.

OBJETIVO: analisar, in vitro, a degradação de força, ao longo do tempo, de elastômeros das marcas comerciais American Orthodontics, Morelli, Ormco e TP Orthodontics. MÉTODOS: a amostra constituiu-se de 80 segmentos de elastômeros em cadeia fechada na cor cinza, divididos em quatro grupos, conforme o fabricante. A distensão foi padronizada em 21mm, com liberação de força inicial variando de 300 a 370g de força. As amostras foram mantidas em saliva artificial em temperatura constante de 37ºC, e a força avaliada nos seguintes intervalos: inicial, 1h, 3h, 5h, 7h, 9h, 1 dia, 7 dias, 14 dias, 21 dias, 28 dias e 35 dias. RESULTADOS: houve diferença estatisticamente significativa na degradação de força entre os grupos avaliados, sendo que no primeiro dia houve perda de 50 a 55% em relação à força inicial. Os valores médios de força em 35 dias variaram de 122 a 148g. CONCLUSÃO: todas as marcas comerciais apresentaram degradação de força ao longo do tempo, sendo que na primeira hora a perda de força esteve entre 59 e 69% da força inicial. Porém, como existe variação dessa degradação dependendo da marca comercial, estudos como esses são importantes para orientação do uso desses elastômeros.

Evaluation of the friction force generated by monocristalyne and policristalyne ceramic brackets in sliding mechanics

OBJECTIVE: To evaluate and compare "in vitro" the maximum friction force generated by three types of esthetic brackets, two types of polycrystalline conventional ceramic brackets (20/40 and InVu) and one type of sapphire monocrystalline bracket (Radiance) in dry and artificial saliva wet settings. Also, to evaluate the influence exerted by artificial saliva on the friction forces of those brackets. METHODS: Tests were performed in dry and artificial saliva wet setting (Oral Balance) by using an EMIC DL 10000 testing machine, simulating a 2 mm slide of 0.019 x 0.025-in rectangular stainless steel wires over the pre-angulated and pre-torqued (right superior canine, Roth prescription, slot 0.022 x 0.030-in) brackets (n = 18 for each bracket). In order to compare groups in dry and wet settings, the ANOVA was used. For comparisons related to the dry versus wet setting, the student t test was used for each group. RESULTS: The results showed that in the absence of saliva the Radiance monocrystalline brackets showed the highest friction coefficients, followed by the 20/40 and the InVu polycrystalline brackets. In tests with artificial saliva, the Radiance and the 20/40 brackets had statistically similar friction coefficients and both were greater than that presented by the InVu brackets. The artificial saliva did not change the maximum friction force of the Radiance brackets, but, for the others (20/40 and InVu), an increase of friction was observed in its presence. CONCLUSION: The InVu brackets showed, in the absence and in the presence of saliva, the lowest friction coefficient.

OBJETIVO: avaliar e comparar in vitro as cargas máximas de atrito geradas por três tipos de braquetes estéticos, sendo dois deles cerâmicos policristalinos convencionais (20/40 e InVu) e um monocristalino de safira (Radiance), em ambientes seco e umedecido por saliva artificial. Também avaliar a influência exercida pela saliva artificial sobre as cargas de atrito dos referidos braquetes. MÉTODOS: os ensaios foram realizados em ambiente seco e em ambiente umedecido com saliva artificial em gel (Oral Balance), utilizando uma máquina de ensaios mecânicos (EMIC, modelo DL10000), simulando um deslizamento de 2mm de fios retangulares 0,019" x 0,025" de aço sobre os braquetes (n = 18, para cada braquete), pré-angulados e pré-torqueados (canino superior direito prescrição Roth, slot 0,022" x 0,030"). Para comparação entre os braquetes, em ambiente seco ou umedecido, utilizou-se a análise de variância; e para a comparação dos braquetes em ambiente seco e umedecido, utilizou-se o teste t para amostras independentes. RESULTADOS: os resultados obtidos indicaram que, na ausência de saliva, os braquetes monocristalinos Radiance demonstraram o maior coeficiente de atrito, seguidos pelos braquetes policristalinos 20/40 e InVu. Nos ensaios realizados em ambiente umedecido, os braquetes Radiance e 20/40 apresentaram coeficientes de atrito estatisticamente semelhantes, e superiores ao apresentado pelos braquetes InVu. A saliva artificial não promoveu alterações na força máxima de atrito para os braquetes Radiance; todavia, para os demais (20/40 e InVu), promoveu aumento significativo nos coeficientes de atrito. CONCLUSÃO: os braquetes InVu apresentaram, tanto nos ensaios realizados na ausência, quanto na presença de saliva, os menores coeficientes de atrito, entre os braquetes ensaiados.

Implantes dentários em zircônia: uma alternativa para o presente ou para o futuro? (Parte II) / Zirconia dental implants: An alternative for today or for the future? (Part II)

Introdução: pesquisas recentes sugerem que os implantes dentários de titânio (Ti) podem ter mais efeitos colaterais do que se acreditava anteriormente. Somando-se aos comprometimentos estéticos dos metais, novas tecnologias com cerâmicas de zircônia (Zr) foram recentemente introduzidas na Odontologia, mantendo as características de sucesso do Ti, porém em reabilitações metal-free. Os resultados clínicos/histológicos com a cerâmica (ZrO2), impulsionados pela conscientização dos pacientes, que buscam estética sem metais, incrementaram sua demanda. Objetivo: encontrar uma alternativa viável aos implantes Ti e identificar os sistemas cerâmicos para uso em humanos, levando-se em conta a biocompatibilidade e a longevidade, apontando as suas vantagens e desvantagens. Métodos: foi realizado um amplo e detalhado levantamento bibliográfico. Conclusões: embora as normas ISO precisem ser revistas, verificou-se que os implantes de zircônia (Y-TZP) têm boas perspectivas para o futuro. O material apresenta maior longevidade nas reabilitações, pela menor adesão bacteriana. Os sistemas de implantes de Zr encontrados nos estudos foram: CeraRoot, Sigma, Z-Systems, Ziterion Zit-Z, Easy-Kon, Zeramex, Whitte Sky, Denti Circon Implants, Zimplant-Biosyr, Omnis-Creamed, White Implants e Ziraldent. Como desvantagens, encontram-se os custos elevados de produção, a necessidade de protetores no período de cura e a possível degradação hidrotérmica do material. Com base nas publicações científicas internacionais, conclui-se que os implantes dentários em Zr (Y-TZP) já são uma alternativa viável para substituir os de Ti, porém não ainda como rotina clínica.

Introduction: Recent research suggests that titanium (Ti) dental implants may have more side effects than previously believed.In addition to the fact that metals compromise aesthetics, emerging technologies involving zirconia(Zr) ceramics were recently introduced in dentistry, whichare proving as effective as Ti, but inmetal-free rehabilitation. The clinical/histological outcomes of ceramics (ZrO2), driven by the awareness of patients seeking aesthetics without metals, have increased their demand.Objective:To find a viable alternative to Ti implants and identify the ceramic systems amenable to use by humans, taking into account biocompatibility and longevity, while pointing out their advantages and disadvantages. Methods: Extensive and detailed bibliography. Conclusions: Although ISO standards need to be reviewed, it has been found that zirconia (Y-TZP) dental implantsshowa promising future. Zirconia increases the longevity oforal rehabilitation given its diminished bacterial adhesion.The following Zr implant systems were found in the studies :CeraRoot, Sigma, Z-Systems, Ziterion Zit-Z, Easy-Kon, Zeramex, White Sky, Denti Circon Implants, Zimplant-Biosyr, Omnis-Creamed, White Implants andZiraldent. Among the disadvantages are a high production cost, the need for protectors duringhealing, and potential hydrothermal degradation of the material. Based on international scientific publications, it was concluded thatZr (Y-TZP) dental implants are now a viable substitute for Ti, although not yet recommended forroutine clinical practice.

Geometria das roscas dos implantes:revisão de literatura / Geometry of implant threads: a review of the literature

Os aspectos biomecânicos de um implante são fundamentalmente diferentes daqueles de um dente natural, circundado por ligamento periodontal. Esse mecanismo de transferência de forças por meio do implante para os tecidos circundantes é um determinante claramente importante no desenvolvimento da interface osso-implante e na longevidade deste. Portanto, é essencial conhecer os fatores relacionados à geometria do implante que influenciam a distribuição do estresse, para determinar o ótimo desenho do implante que minimizará as tensões. O objetivo deste trabalho foi o de realizar uma revisão de literatura para conhecer os diferentes tipos de roscas e sua influência na transmissão das tensões aos tecidos circundantes. Para isso, foi realizada uma busca em 2 bases de dados: MEDLINE e Biblioteca Cochrane desde 1977 a 2008. Os critérios de inclusão e exclusão foram: artigos clínicos, laboratoriais e de revisão que estudavam ou comparavam a geometria das roscas dos implantes. Foram localizados 156 artigos, sendo seleccionados 31. Conclui-se que o formato das roscas deve objetivar maximizar a força e estabilidade interfacial assim como a transferência de cargas para o osso de forma mais bem distribuída, melhorando, assim, o prognóstico do implante em longo prazo.

The biomechanical aspects of an implant are fundamentally different from those of a natural tooth, surrounded by a periodontal ligament. This mechanism of the transfer of forces by means of the implant to the surrounding tissues is a clearly important determinant in the development of the bone-implant interface and in longevity of the implant. It is therefore essential to know the factors relating to the geometry of the implant that influence the distribution of stress in order to determine an implant design that will minimize the stress. The purpose of this study was to undertake a review of the literature in order to become acquainted with the different types of implant threads and their influence on the transmission of stress to the surrounding structures. To this end two data bases were consulted: MEDLINE and the Cochrane Library from 1977 to 2008. The inclusion and exclusion criteria were as follows: clinical, laboratory and review articles that examined or compared the geometry of implant threads. Of the 156 articles found, 31 were selected. It was concluded that thread format should maximize strength and interfacial stability, as well as load transfer to the bone in the best distributed manner, thereby improving the long-term prognosis of the implant.

Biomateriais em Cirurgia Craniomaxilofacial: princípios básicos e aplicações - revisão de literatura / Biomaterials in Craniomaxilofacial Surgery: basic principals andapplications - literature revision

Na Medicina, os biomateriais possuem múltiplas aplicações ou finalidades. Seu uso necessita do conhecimento das propriedades do material e das características de seu sítio receptor. Estetrabalho promove uma revisão do uso dos biomateriais na Cirurgia Craniomaxilofacial, enfatizando sua definição, classes/tipos e propriedades.

The biomaterials have a lot of due or applications. Their use needs the knowledge of its proprieties and receptor characteristics. This is a review of the biomaterials use in Craniomaxillofacial Surgery, emphasizing the definition, classes/types and proprieties.

Chest wall resection and reconstruction:an update / 第二军医大学学报

Chest wall resection and reconstruction remains a severe challenge for reconstructive surgeons,which often leads to conservative treatment regimens in clinical practice,consequently resulting in poor outcomes(high morbidity and mortality).In recent 20 years,advances in muscle flap surgery and availability of chest reconstructive prosthesis have encouraged the surgeons to take an active attitude toward chest wall resection;many "unresectable" lesions now have a chance to be resected and cured.This article reviews the problems concerning the principles for chest wall resection,reconstruction,prosthesis selection,etc.in chest wall reconstruction.