Exploring a reversible adaptation of conventional HPLC for capillary-scale operation.

This study introduces a feasible approach for utilizing a conventional High-Performance Liquid Chromatography (HPLC) instrument at the capillary scale (1 - 10 µL/min). The development of an active flow splitter and an adapted UV-visible (UV-vis) detection cell are described. The system employs an Arduino Uno board to monitor a flow sensor and control a stepper motor that automates a split valve to achieve capillary-scale flow rates from a conventional pump. A capillary UV-vis cell compatible with conventional detectors, featuring an optical path length with a volume of 14 nL, was developed to address the detection challenges at this scale and minimize extra column band broadening. The system performance was assessed by a lab-packed LC capillary column with 0.25 mm x 15 cm dimensions packed with 3.0 µm C18 particles. Model compounds, particularly polycyclic aromatic hydrocarbons (PAHs), were employed to assess the functionality of all developed components in terms of theoretical plates, resolution, and band broadening. The proposed system is a profitable, reliable, and cost-effective tool for miniaturized liquid chromatography.

Antioxidant and Antibacterial Activity of Mexican Oregano Essential Oil, Extracted from Plants Occurring Naturally in Semiarid Areas and Cultivated in the Field and Greenhouse in Northern Mexico.

In recent years, the determination of the antioxidant and antibacterial activity of essential oils in wild plants, such as Mexican oregano (Lippia graveolens Kunth), has become increasingly important. The objective was to compare the antioxidant and antibacterial activity of Mexican oregano essential oil obtained from plants occurring naturally in semiarid areas (Wild1 and Wild2), and those cultivated in the field (CField) and greenhouse (CGreenhouse) in northern Mexico. The Mexican oregano essential oil extraction was performed using the hydrodistillation method, the antioxidant activity was determined using the ABTS method, and the antibacterial activity was assessed through bioassays under the microwell method at nine different concentrations. The aim was to determine the diameter of the inhibition zone and, consequently, understand the sensitivity level for four bacterial species. The results revealed an antioxidant activity ranging from 90% to 94% at the sampling sites, with Wild1 standing out for having the highest average antioxidant activity values. Likewise, six out of the nine concentrations analyzed showed some degree of sensitivity for all the sampling sites. In this regard, the 25 µL mL-1 concentration showed the highest diameter of inhibition zone values, highlighting the Wild2 site, which showed an average diameter greater than 30 mm for the four bacteria tested. Only in the case of S. typhi did the CGreenhouse site surpass the Wild2, with an average diameter of the inhibition zone of 36.7 mm. These findings contribute to the search for new antioxidant and antibacterial options, addressing the challenges that humanity faces in the quest for opportunities to increase life expectancy.

Experimental data of heat transfer nanofluids for trigeneration systems: viscosity at below-ambient temperatures.

The present work exhibits the dynamic viscosity profile data of three distinct nanofluids, at a constant shear stress, and within a range of temperatures that include below-ambient conditions (from -10 to 20 °C). The nanofluids were as follows. Nanofluid I: 30% ethylene glycol and 70% distilled water (v/v), with graphene (0.32% in mass); Nanofluid II: 30% engine coolant NBR 13705; ASTM D-3306; ASTM D-4985) and 70% distilled water (v/v), with graphene (0.2% in mass); and Nanofluid III: 30% engine coolant and 70% distilled water (v/v), with Multi-Walled Carbon Nanotubes (MWCNT) (0.2% in mass). The present work was motivated by the scarcity of experimental data on the temperature dependence of viscosity for graphene, MWCNT, and their hybrid nanofluids, at below-ambient temperatures.

Risk Factors for Peri-intubation Cardiac Arrest in a Pediatric Emergency Department.

OBJECTIVES: Cardiac arrest is a significant complication of emergent endotracheal intubation (ETI) within the pediatric population. No studies have evaluated risk factors for peri-intubation cardiac arrest (PICA) in a pediatric emergency department (ED) setting. This study identified risk factors for PICA among patients undergoing emergent ETI in a pediatric ED. METHODS: We performed a nested case-control study within the cohort of children who underwent emergent ETI in our pediatric ED during a 9-year period. Cases were children with PICA within 20 minutes of ETI. Controls (4 per case) were randomly selected children without PICA after ETI. We analyzed potential risk factors based on published data and physiologic plausibility and created a simple risk model using univariate results, model fit statistics, and clinical judgment. RESULTS: In the cohort of patients undergoing ETI, PICA occurred in 21 of 543 subjects (3.9%; 95% confidence interval [CI], 2.2-5.9%), with return of spontaneous circulation in 16 of 21 (76.2%; 95% CI, 52.8-91.8%) and survival to discharge in 12 of 21 (57.1%; 95% CI, 34.0-78.2%). On univariate analysis, cases were more likely to be younger, have delayed capillary refill time, systolic or diastolic hypotension, hypoxia, greater than one intubation attempt, no sedative or paralytic used, and pulmonary disease compared with controls. Our 4-category risk model for PICA combined preintubation hypoxia (or an unobtainable pulse oximetry value) and younger than 1 year. The area under the receiver operating characteristic curve for this model was 0.87 (95% CI, 0.77-0.97). CONCLUSIONS: Hypoxia (or an unobtainable pulse oximetry value) was the strongest predictor for PICA among children after emergent ETI in our sample. A simple risk model combining pre-ETI hypoxia and younger than 1 year showed excellent discrimination in this sample. Our results require independent validation.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study.

The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 µm and 0.248 µm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study

Abstract The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 μm and 0.248 μm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Resumo Os objetivos deste estudo in vivo foram avaliar o efeito da colagem com cimento de ionômero de vidro modificado por resina (CIVMR) e a rugosidade da superfície do esmalte antes e após a remoção dos braquetes colados com compósito ou CIVMR em incisivos centrais superiores. Quinze pacientes ortodônticos foram selecionados para o estudo. Para cada paciente, os dentes foram lavados e secos, e os braquetes colados com compósito (Transbond XT) e CIVMR (Vitremer Core Buildup / Restorative). Ao término do tratamento ortodôntico, os braquetes foram removidos. As réplicas dentais foram confeccionadas em resina epóxica nas condições iniciais (antes da colagem) e após o polimento com sistema de discos de óxido de alumínio. O índice de remanescente adesivo (IRA) e a rugosidade da superfície foram mensurados nas réplicas dentais e os dados foram avaliados estatisticamente por Mann-Whitney e teste t pareado, respectivamente. Não ocorreu descolagem de braquetes durante os períodos de tratamento dos pacientes. Verificou-se que os valores do IRA dos dois incisivos centrais superiores foram semelhantes (p = 0,665). Para ambos os materiais de colagem, o valor de IRA predominante foi 3. Após o polimento, a rugosidade da superfície do esmalte foi semelhante nos grupos compósito (0,245 μm) e CIVMR (0,248 μm) (p = 0,07). Em ambos os grupos, os valores de rugosidade da superfície do esmalte foram significativamente menores após o polimento em comparação com a condição inicial (p <0,001). CIVMR promoveu eficiência na colagem de braquetes sem falhas durante o tratamento; a escolha dos materiais compósito ou CIVMR não foi um fator que influenciou na rugosidade da superfície do esmalte, porém, o polimento levou a superfícies mais lisas do que as encontradas no início do tratamento.

Evaluation of the Physical-Mechanical Properties of Type IV Gypsum / Avaliação das Propriedades Físico-Mecânicas de Gessos Odontológicos Tipo IV

The purpose of this study was to evaluate a physical property (surface roughness) and a mechanical property (microhardness) of four type IV gypsum. 40 specimens were prepared from a metal matrix that reproduced an edentate upper alveolar ridge. They were divided into 4 groups (n = 10 Clone (G3), Durone(G4), SSWhite (G2), Asfer (G1) and submitted to roughness and microhardness tests . The obtained data were submitted to statistical analysis. By the Kolmogorov-Smirnov test it was verified that there was non-parametric distribution of the samples. The non-parametric Kruskal-Wallis and Mann-Whitney-U tests were applied in hardness and roughness data. In microhardness group 3(Clone) presented the best values (103.0 HV). In surface roughness (Ra), group 3(Clone) and Group 2 (SSWhite) showed the lowest values (1.8 µm) and all evaluated groups presented higher values than those found in metallic matrix (baseline). It was concluded that gypsum models obtained from molds with irreversible hydrocolloid are rougher than molded surface, regardless of the commercial brand. The samples made with the Clone gypsum (G3) have the highest microhardness.(AU)

O objetivo desse trabalho foi avaliar uma propriedade física (rugosidade superficial) e uma propriedade mecânica (microdureza) de quatro marcas comerciais de gesso tipo IV. Foram confeccionados 40 corpos de prova a partir de uma matriz metálica que reproduzia um rebordo alveolar superior edentado. Os mesmos foram divididos em 4 grupos (n=10), de acordo com as marcas comerciais (Clone, Durone, SSWhite, Asfer), e submetidos aos testes de rugosidade e microdureza superficial utilizando um rugosímetro e um microdurômetro respectivamente. Os dados obtidos foram computados e submetidos à análise estatística. Pelo teste de Kolmogorov-Smirnov verificou-se que não houve distribuição Normal das amostras. Dessa forma foram aplicados os testes não paramétricos de Kruskal-Wallis e Mann Whitney-U em ambas as análises. Na microdureza, a marca comercial Clone apresentou os melhores valores (103,0). Já na rugosidade superficial as marcas comerciais Clone e SSWhite apresentaram os menores valores (1,8). Ainda em relação à rugosidade superficial, as marcas comerciais avaliadas apresentaram valores maiores que os encontrados na matriz metálica. Concluiu-se que modelos em gesso obtidos a partir de moldes com hidrocolóide irreversível apresentam-se mais rugosos que a superfície moldada, independente da marca comercial avaliada. Os modelos em gesso confeccionados com a marca Clone apresentam melhor microdureza superficial. (AU)

Systemic diseases and other painful conditions in patients with temporomandibular disorders and migraine.

Temporomandibular disorders (TMD) are a highly prevalent, painful musculoskeletal condition affecting the masticatory system, and are frequently associated with migraines (M) and other diseases. This study aimed to investigate the association between painful TMD and M with other painful conditions and systemic diseases, such as cervicalgia, body pain (BP), ear-nose-throat disorders, musculoskeletal disorders, diabetes, cardiopulmonary diseases and gastritis/peptic ulcer. METHODS: This was a cross-sectional study conducted in a sample of 352 individuals. Participants were stratified into three groups according to the presence of painful TMD and M: controls [individuals free of TMD and any headache (HA)]; TMD only (presence of painful TMD, but free of any HA); and TMD+M (presence of painful TMD and M). TMD was classified according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) - Axis I. Nonspecific physical symptoms (NSPS) were assessed by RDC/TMD - Axis II. The International Classification of Headache Disorders - II criteria, second edition, were applied to identify and classify primary HA. Other painful conditions and systemic diseases were assessed by volunteers' self-report. The prevalence of all assessed conditions was higher in the TMD+M group. Multiple regression models showed that cervicalgia was associated with the TMD only group (p<0.05), whereas gender (p<0.05), cervicalgia (p<0.05), BP (p<0.05) and NSPS (p<0.05) were significantly associated with the TMD+M group. Our results suggest that individuals with a comorbidity (TMD associated with M) have a more severe condition than those presenting only painful TMD.

Effect of different surface treatments on the ceramic veneer surface: morphological analysis / Efeito de diferentes tratamentos na superfície da cerâmica de revestimento: análise morfológica

Objective: The aim of this study was to evaluate the effect of different surface clinical treatments on the roughness (Ra) of a lithium disilicate ceramic veneer. Material and Methods: Forty-eight lithium disilicate discs with ceramic veneer and glaze layer were manufactured and distributed into six groups (n=8) according to the surface treatment performed: G1, glaze layer (control group); G2, diamond bur 4138F; G3, diamond bur 4138F + 4138FF; G4, diamond bur 4138F + new glaze layer; G5, diamond bur 4138F + ceramic polishing kit; G6, diamond bur 4138F + rubber cup with diamond paste + felt with diamond paste. Surface Ra measurement (µm) was performed using a profilometer before and after surface treatments, and one specimen from each group was subjected to Scanning Electron Microscopy (SEM) after treatment. Two-way ANOVA and Tukey's test (5%) were used for data analysis. Results: Group 2 (3,00 ± 0,61)b showed higher values of Ra, followed by Group 3 (1,93 ± 0,45)c , Group 6 (1,56 ± 0,22) ac, Group 5 (1,14 ± 0,68)a and Group 4 (0,90 ± 0,26)a . G4, G5 and G6 were not different between each other and control group (1,11 ± 0,21)a . SEM imaging revealed surface smoothness in G1, G4 and G5, and presence of irregularities in G2, G3 and G6. Conclusion: it is possible to conclude that different surface clinical treatments influences the roughness of a lithium disilicate ceramic veneer (AU)

Objetivo: o objetivo deste estudo foi avaliar o efeito de diferentes tratamentos clínicos de superfície na rugosidade (Ra) de uma cerâmica de cobertura de dissilicato de lítio. Material e Métodos: foram fabricados e distribuídos quarenta e oito discos de dissilicato de lítio com cerâmica de revestimento e vitrificação em seis grupos (n = 8) de acordo com o tratamento de superfície realizado: G1, camada vitrificada (control group); G2, ponta diamantada 4138F; G3, ponta diamantada 4138F + 4138FF; G4, ponta diamantada 4138F + nova camada vitrificada; G5, ponta diamantada 4138F + kit de polimento cerâmico; G6, ponta diamantada 4138F + taça de borracha com pasta diamantada + feltro com pasta diamantada. A análise da superfície Ra (µm) foi realizada usando-se um perfilômetro antes e depois dos tratamentos de superfície, e uma amostra de cada grupo foi à Microscopia Eletrônica de Varredura (MEV) após o tratamento. Two-way ANOVA e o teste de Tukey (5%) foram utilizados para análise de dados. Resultados: O Grupo 2 (3,00 ± 0,61)b apresentou valores mais altos de Ra, seguido do Grupo 3 (1,93 ± 0,45) c , Grupo 6 (1,56 ± 0,22)ac, Grupo 5 (1,14 ± 0,68)a e Grupo 4 (0,90 ± 0,26)a . G4, G5 e G6 não eram diferentes entre si e entre grupo de controle (1,11 ± 0,21)a . A imagem de MEV revelou suavidade da superfície em G1, G4 e G5, e presença de irregularidades em G2, G3 e G6. Conclusão: é possível concluir que diferentes tratamentos clínicos de superfície influenciam a rugosidade de uma cerâmica de revestimento de dissilicato de lítio.(AU)

Systemic diseases and other painful conditions in patients with temporomandibular disorders and migraine

Abstract Temporomandibular disorders (TMD) are a highly prevalent, painful musculoskeletal condition affecting the masticatory system, and are frequently associated with migraines (M) and other diseases. This study aimed to investigate the association between painful TMD and M with other painful conditions and systemic diseases, such as cervicalgia, body pain (BP), ear-nose-throat disorders, musculoskeletal disorders, diabetes, cardiopulmonary diseases and gastritis/peptic ulcer. Methods: This was a cross-sectional study conducted in a sample of 352 individuals. Participants were stratified into three groups according to the presence of painful TMD and M: controls [individuals free of TMD and any headache (HA)]; TMD only (presence of painful TMD, but free of any HA); and TMD+M (presence of painful TMD and M). TMD was classified according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) - Axis I. Nonspecific physical symptoms (NSPS) were assessed by RDC/TMD - Axis II. The International Classification of Headache Disorders - II criteria, second edition, were applied to identify and classify primary HA. Other painful conditions and systemic diseases were assessed by volunteers' self-report. The prevalence of all assessed conditions was higher in the TMD+M group. Multiple regression models showed that cervicalgia was associated with the TMD only group (p<0.05), whereas gender (p<0.05), cervicalgia (p<0.05), BP (p<0.05) and NSPS (p<0.05) were significantly associated with the TMD+M group. Our results suggest that individuals with a comorbidity (TMD associated with M) have a more severe condition than those presenting only painful TMD.

Associação Radiográfica entre Ponticulus Posticus e as alterações Morfológicas Condilares / Associação Radiográfica entre Ponticulus Posticus e as alterações Morfológicas Condilares

O ponticulus posticus (PP) é definido como uma pequena ponte óssea formada entre a porção posterior do processo articular superior e a porção posterolateral da margem superior do arco posterior da vértebra atlas. A fisiopatologia do PP pode ser relatada pela compressão vascular da artéria vertebral e nervo suboccipital, levando a isquemia circulatória e dor de cabeça cervicogênica, ou por disfunção mecânica da articulação atlanto-occiptal, resultando no tracionamento da dura máter ou iniciando um processo neurodinâmico. O objetivo deste estudo foi avaliar a associação entre PP e alterações morfológicas condilares, por meio das radiografias panorâmicas e teleradiografia lateral. Foram selecionados 1200 pacientes que realizaram documentação ortodôntica em uma clínica de radiologia. O PP foi avaliado e classificado em parcial ou completo. Os dados foram tabulados no SPSS e analisados por regressão logística multinomial. Houve diferença estatística significativa na prevalência do PP parcial entre homens e mulheres (P< 0,001), com odds ratio de 1,91 (95% IC 1,34-2,71), e na prevalência do PP complete (P = 0,002), com odds ratio de 1,72 (95% IC 1,21-2,43). Diferença estatística também foi encontrada na associação entre alteração morfológica condilar e PP complete (P = 0,004). Concluiu-se que o PP é mais prevalente em homens e que existe correlação entre a presença do PP completa e alterações morfológicas condilares. (AU).

The ponticulus posticus (PP) is defined as an abnormal small bony bridge formed between the posterior portion of the superior articular process and the posterolateral portion of the superior margin of the posterior arch of the atlas. The pathophysiology may be related to pressure applied on the vertebral artery and the suboccipital nerve root, and may be a possible cause of posterior circulation ischaemia and cervicogenic headache, or mechanical dysfunction at the atlanto-occipital joint resulting in traction of the dura mater or initiation of neurodynamic processes. The objective was to determine the prevalence of PP and to assess whether there is an association between this condition and changes in condylar morphology, evaluated using digital panoramic and lateral cephalometric radiographs. A sample of 1200 patients was selected. The patients were referred to a radiology clinic for orthodontic evaluation. PP was classified as either partial or complete PP. Data were entered into an SPSS spreadsheet and analysed by multinomial logistic regression. There was a significant difference in the prevalence of partial PP between males and females (P< 0.001), with an odds ratio of 1.91 (95% CI 1.34-2.71), and in the prevalence of complete PP (P = 0.002), with an odds ratio of 1.72 (95% CI 1.21-2.43). A significant difference was found for the association between condylar morphological changes and complete PP (P = 0.004). It was concluded that PP is more prevalent in men, and there is a correlation between the presence of complete PP and changes in condylar morphology. (AU).

Influence of different water types on the physical and mechanical properties of gypsum

Abstract Aim: To evaluate if gypsum mixed with different water types, with their different compositions influence the dimensional change, surface roughness and compressive strength of type IV and V gypsum specimens. Methods: Sixty specimens were fabricated from metal matrices and divided into six groups (n=10) according to the used type of gypsum and water: G1, G2 and G3 - type IV gypsum and tap, mineral and distilled water, respectively; G4, G5 and G6 - type V gypsum and tap, mineral and distilled water, respectively. Water/powder ratio followed the manufacturer's recommendations (19 mL/100 g) in all groups. The same specimens were used for all tests. A micrometer dial evaluated the dimensional change. The surface roughness of three random points was determined with a rugosimeter; a universal testing machine performed the compressive strength test. The data were subjected to analysis of variance (ANOVA). Results: There was no statistically significant difference (p>0.05) between the three types of water in the studied variables. There was statistically significant difference (p<0.05) between the gypsum mixes for the dimensional change variable. Conclusions: The different water types, with their different compositions, did not influence the analyzed physical and mechanical properties.

In-vivo evaluation of the surface roughness and morphology of enamel after bracket removal and polishing by different techniques.

INTRODUCTION: The aim of this study was to evaluate the surface roughness and morphology of enamel with a surface roughness tester and scanning electron microscopy after the removal of metal brackets and polishing. METHODS: Ten orthodontic patients were selected for the study. At the conclusion of orthodontic treatment, their metal brackets were removed. For each patient, teeth on one side of the mouth were randomly chosen for finishing and polishing with aluminum oxide discs (n = 10). Teeth on the other side were finished with multilaminated carbide burs (n = 10). Dental replicas (before and after tooth polishing) were obtained with epoxy resin. Three surface roughness measurements were made in different directions with an angle of 120° among them, and a mean for each dental replica was calculated. The roughness data were statistically evaluated by repeated-measurements analysis of variance. Three specimens from each group were also used for scanning electron microscopy analysis. RESULTS: After resin removal, the average roughness in the carbide bur group (0.31 µm) was significantly greater than that in the aluminum oxide disc group (0.25 µm). CONCLUSIONS: The aluminum oxide disc polishing system resulted in less enamel roughness than did the multilaminated carbide bur system.

Sistemas adesivos: conceito, aplicação e efetividade / Adhesive systems: concept, aplication and effectiveness

Com o avanço ocorrido na Odontologia Restauradora nos últimos anos, o que se busca como adesão dos materiais restauradores resinosos aos substratos dentais mineralizados, com o uso dos sistemas adesivos, tem evoluído de forma significativa. Quando em esmalte, a adesão se mostra confiável e segura, garantindo sucesso clínico ao procedimento realizado. Entretanto, quando o substrato é a dentina, a adesão via hibridização do tecido é mais complexa, pois essa se apresenta heterogênea e repleta de particularidades. Assim, o objetivo deste trabalho é, por meio de um levantamento bibliográfico, expor e discutir os diferentes sistemas adesivos atualmente encontrados no mercado, seus conceitos, técnicas de aplicação e desempenho clínico, a fim de contribuir para que o leitor possa compreender a funcionalidade dos sistemas adesivos e, a partir de então, saber escolher pelo que atende às suas necessidades clínicas.

With the advance occurred in restorative dentistry in recent years, which is seeking as bonding of resinous restorative materials to mineralized dental substrates with the use of adhesive systems, has developed significantly. When it is done in enamel, adhesion is reliable and safe, ensuring success of the procedure. However, when the substrate is dentin, adhesion by hybridization of the tissue is more complex because it is heterogeneous and full of features. The objective of this study is, by a literature review, explain and discuss the different adhesive systems currently available in the market, its concepts, application techniques and clinical performance to help the reader to understand the functionality of adhesive systems and, thereafter, to choose for what suits your clinical needs.

Microwave spectra, structure, and dynamics of the weakly bound complex, N2 CO2.

The Fourier transform microwave spectra of the various isotopologs of the weakly bound complex of carbon dioxide with the most abundant molecule in the atmosphere, nitrogen, have been measured. The structure of the complex has been determined and evidence for the inversion of the N(2) is presented. The molecule is T-shaped, with the OCO forming the cross of the T, a structure consistent with that deduced from a previous rotationally resolved infrared experiment. A significant wide-amplitude bending motion of the N(2) is deduced from the values of the (nearly identical) nuclear quadrupole coupling constants of the nitrogen nuclei. The spectroscopic results are compared with high-quality ab initio calculations. We examine the consequences of the N(2) CO(2) complex formation in the atmosphere upon the greenhouse warming potential of carbon dioxide.

Restabelecimento do espaço interarcos - uma abordagem multidisciplinar / Reestablishment of the intermaxillary space: a multidisciplinary approach

O restabelecimento do espaço interarcos pode ser obtido através da osteotomia segmentar posterior da maxila. Esta consiste na mobilização e movimentação de um segmento posterior da maxila com o objetivo de restabelecer o espaço protético adequado entre a maxila e a mandíbula, além de corrigir mordidas cruzadas, mordidas abertas posteriores, proporcionando o reposicionamento superior, inferior, distal e mesial do segmento em um único tempo operatório. As indicações, técnicas e complicações da osteotomia segmentar posterior da maxila serão discutidas por meio de uma revisão de literatura e relato de um caso, na qual é enfatizada a necessidade do envolvimento de duas especialidades odontológicas.

The influence of mold temperature on the fit of cast crowns with commercially pure titanium.

Commercially pure titanium (CP Ti) has been widely applied to fabricate cast devices because of its favorable properties. However, the mold temperature recommended for the manufacture of casts has been considered relatively low, causing inadequate castability and poor marginal fit of cast crowns. This study evaluated and compared the influence of mold temperature (430 degrees C--as control, 550 degrees C, 670 degrees C) on the marginal discrepancies of cast CP Ti crowns. Eight bovine teeth were prepared on a mechanical grinding device and impressions were used to duplicate each tooth and produce eight master dies. Twenty-four crowns were fabricated using CP Ti in three different groups of mold temperature (n = 8): 430 degrees C (as control), 550 degrees C and 670 degrees C. The gap between the crown and the bovine tooth was measured at 50 X magnification with a traveling microscope. The marginal fit values of the cast CP Ti crowns were submitted to the Kruskal-Wallis test (p = 0.03). The 550 degrees C group (95.0 microm) showed significantly better marginal fit than the crowns of the 430 degrees C group (203.4 microm) and 670 degrees C group (213.8 microm). Better marginal fit for cast CP Ti crowns was observed with the mold temperature of 550 degrees C, differing from the 430 degrees C recommended by the manufacturer.

The influence of mold temperature on the fit of cast crowns with commercially pure titanium

O titânio comercialmente puro (Ti c.p.) tem sido largamente empregado na elaboracão de estruturas protéticas fundidas devido às suas propriedades favoráveis. Entretanto, a temperatura do molde recomendada pelo fabricante tem sido considerada baixa, causando inadequada fundibilidade e precária adaptacão marginal de coroas fundidas. Este estudo avaliou e comparou a influência de temperaturas do molde (430ºC - como controle, 550ºC, 670ºC) na discrepância marginal de coroas fundidas em Ti c.p. Oito dentes bovinos foram preparados em um torno mecânico e moldados para produzirem oito modelos-mestre. Vinte e quatro coroas foram confeccionadas em Ti c.p. para três grupos de temperatura do molde (n = 8): 430ºC (como controle), 550ºC e 670ºC. A fenda marginal entre a coroa e o dente bovino foi observada em microscópio mensurador (50 X). Os valores de adaptacão marginal das coroas fundidas em Ti c.p. foram submetidos ao teste de Kruskal-Wallis (p = 0,03). O grupo fundido a 550ºC (95,0 µm) exibiu adaptacão marginal significativamente melhor que as coroas dos grupos 430ºC (203,4 µm) e 670ºC (213,8 µm). Foi observada melhor adaptacão marginal das coroas fundidas em Ti c.p. com a temperatura do molde a 550ºC, diferindo da temperatura recomendada pelo fabricante, de 430ºC.

Processo de fundição do titânio e de suas ligas na área de reabilitação oral / Casting procedure of titanium and its alloys in oral rehabilitation area

O titânio e suas ligas tem despertado grande interesse na Odontologia e, em especial, na área de prótese dental, considerando suas propriedades favoráveis como alta resistência mecânica e baixo peso específico. A sua técnica de fundição é pouco disseminada e difere dos métodos convencionais. Assim, o objetivo desse trabalho é descrever o processo de fundição do titânio comercialmente puro e ligas dele derivadas, destacando as principais características físicas e mecânicas desse metal e sua perspectiva para aplicação em próteses convencionais (prótese parcial fixa e prótese parcial removível) e próteses sobre implantes

Fit of cast commercially pure titanium and Ti-6Al-4V alloy crowns before and after marginal refinement by electrical discharge machining.

STATEMENT OF PROBLEM: Titanium has been suggested as a replacement for alloys currently used in single-tooth restorations and fixed partial dentures. However, difficulties in casting have resulted in incomplete margins and discrepancies in marginal fit. PURPOSE: This study evaluated and compared the marginal fit of crowns fabricated from a commercially pure titanium (CP Ti) and from Ti-6Al-4V alloy with crowns fabricated from a Pd-Ag alloy that served as a control. Evaluations were performed before and after marginal refinement by electrical discharge machining (EDM). MATERIAL AND METHODS: Forty-five bovine teeth were prepared to receive complete cast crowns. Stone and copper-plated dies were obtained from impressions. Fifteen crowns were cast with each alloy (CP Ti, Ti-6Al-4V, and Pd-Ag). Marginal fit measurements (in micrometers) were recorded at 4 reference points on each casting with a traveling microscope. Marginal refinement with EDM was conducted on the titanium-based crowns, and measurements were repeated. Data were analyzed with the Kruskal-Wallis test, paired t test, and independent t test at a 1% probability level. RESULTS: The Kruskal-Wallis test showed significant differences among mean values of marginal fit for the as-cast CP Ti crowns (mean [SD], 83.9 [26.1] microm) and the other groups: Ti-6Al-4V (50.8 [17.2] microm) and Pd-Ag (45.2 [10.4] microm). After EDM marginal refinement, significant differences were detected among the Ti-6Al-4V crowns (24.5 [10.9] microm) and the other 2 groups: CP Ti (50.6 [20.0] microm) and Pd-Ag (not modified by EDM). Paired t test results indicated that marginal refinement with EDM effectively improved the fit of CP Ti crowns (from 83.9 to 50.6 microm) and Ti-6Al-4V crowns (from 50.8 to 24.5 microm). However, the difference in improvement between the two groups was not significant by t test. CONCLUSION: Within the limitations of this study, despite the superior results for Ti-6Al-4V, both groups of titanium-based crowns had clinically acceptable marginal fits. After EDM marginal refinement, the fit of cast CP Ti and Ti-6Al-4V crowns improved significantly.