Efeito de um primer para metais sobre a força de união da interface metal-resina

Para avaliar o efeito de diferentes tratamentos superficiais sobre a resistência ao cisalhamento da união entre uma liga metálica (Co-Cr-Mo - Remanium CD) e um cimento resinoso (Rely X TM) e analisar o tipo de fratura durante a separação dos espécimes, quarenta pares de discos metálicos foram fundidos, regularizados e polidos, submetidos a quatro ciclos térmicos (vácuo, 960ºC, 8 minutos) e divididos aleatoriamente em quatro grupos. Cada grupo recebeu um tipo de tratamento: Grupo PSP: Polimento com lixa d'água Nº 600; Grupo PCP: Polimento com lixa 600 e aplicação do condicionador metálico Alloy Primer (Kuraray); Grupo JSP: Jato de óxido de alumínio de 100µm, e Grupo JCP: Jato de óxido de alumínio de 100mm, e aplicação do Alloy Primer. Os grupos foram cimentados e armazenados em água destilada a 37ºC por 36 horas e submetidos ao ensaio de resistência ao cisalhamento. A média e o desvio padrão (em kgf/cm²) obtidos para cada grupo foram: PSP 4,0/0,4; PCP 88,9/33,6; JSP 163,2/27,6; JCP 144,5/54,0. Após a análise estatística os autores concluíram que: os maiores valores foram produzidos pelos grupos jateados (JSP, JCP), independentemente da aplicação do primer; o Alloy Primer aumentou a retentividade entre o cimento Rely X e a superfície polida da liga de Co-Cr-Mo, entretanto sua força de união não superou a alcançada através do jateamento; todos os espécimes apresentaram falha adesiva na interface testada.To evaluate the effect of different surface treatments on shear bond strength between a metallic alloy (Co-Cr-Mo - Remanium CD) and a resin cement (Rely X TM) and to evaluate the mode of fracture after testing, forty couples of metallic-alloy disks were melted, regularized, polished, submitted to four thermal cycles (Vacuum, 960ºC, 8 minutes) and randomly separated into four groups. Each group received a different type of treatment: Group PSP: Polished with sandpaper 600; Group PCP: Polished with sandpaper 600 and application of the metal primer Alloy Primer (Kuraray); Group JSP: Sandblasted with 100µm aluminum oxide; Group JCP: Sandblasted with 100mm aluminum oxide and treated with a metal Primer. The groups were cemented and stored in distilled water at 37ºC for 36 hours and submitted to the shear bond strength test. The mean and standard deviation (in Kgf/cm²) obtained for each group was: PSP 4.0/0.4; PCP 88.9/33.6; JSP 163.2/27.6; JCP 144.5/54.0. After the statistical analysis the authors concluded that: the highest values were obtained for the sandblasted groups (JSP, JCP), regardless of the primer application; the Alloy Primer increased the retention between the Rely X cement and the polished surface of the Co-Cr-Mo alloy, yet its bond strength was not greater than that obtained with sandblasting; all specimens showed adhesive failures in the tested interface

Evaluation of the force generated by gradual deflection of 0.016-inch NiTi and stainless steel orthodontic wires in self-ligating metallic and esthetic brackets

The purpose of this study was to evaluate the deflection forces of 0.016-inch Nitinol and stainless steel orthodontic wires, in association to different self-ligating brackets. Specimens were mounted in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342), using a 10N load cell and ISO 15,841, as a protocol. Eight of these models were prepared, each one for the bonding of each set of self-ligating accessories to be tested: Damon Q, Damon Clear (Ormco), In-Ovation R, In-Ovation C (GAC), BioQuick, QuickClear (Forestadent), SmartClip and Clarity SL (3M). Data were subjected to One-way ANOVA, followed by Tukey tests (P<0.05). Elastic deflection results showed that the deactivation forces increased with increase in wire deflection in the different brackets evaluated. For the different combinations, Clarity SL generated the greatest force and Damon Clear presented the lowest force when compared to the other brackets in all alloys and deflections. BioQuick and QuicKlear were those with the most similar behavior with each other. Strength values increased with gradual increase in wire deflection in all evaluated brackets. Clarity SL generated the greatest and Damon Clear the lowest force when compared to the other brackets in all alloys and deflections tested

Water sorption and solubility of different calcium hydroxide cements

OBJECTIVES: Calcium hydroxide cements have been largely used in deep cavities due to their abilities to stimulate dentin formation. However, their resistance can be relatively low and their solubility relatively high, in many instances. This study evaluated water sorption and solubility of different calcium hydroxide cements, in order to show alterations that may reduce their effectiveness. MATERIAL AND METHODS: Five discs (20 mm in diameter and 1.5 mm thick) of three different materials (Biocal®, Dycal® and Hidro C®) were prepared with the aid of a ring-shaped metallic matrix. After being stored at 37ºC for 24 h, the discs were weighed on a precision weight scale, dehydrated and weighed again. Immediately after weighing, discs were stored for a week in 50 mL of distilled water at 37ºC and, then, weighed again, dehydrated and submitted to a new weighing. The loss of soluble material and its water sorption was obtained from the difference between the initial and the final dry mass of each disc, after 1 week of immersion in water. Data were analyzed for significant differences by two-way ANOVA and Tukey's test (p<0.05). RESULTS: Mean water sorption values (g) ± standard deviation and percentage (%), for each evaluated cement, were: Biocal® (0.006 ± 0.001 / 2.15); Dycal® (0.016 ± 0.004 / 5.49); and Hidro C® (0.025 ± 0.003 / 8.27). Mean solubility values (g) ± standard deviation and percentage (%), for each evaluated cement, were: Biocal® (0.002 ± 0.001 / 0.72); Dycal® (0.013 ± 0.004 / 4.21); and Hidro C® (0.023 ± 0.004 / 7.65). CONCLUSIONS: Biocal® absorbed less water and was less soluble than the other evaluated cements; Hidro C® exhibited the highest water sorption and solubility values; and there were significant differences among all evaluated experimental groups

Water sorption and solubility of different calcium hydroxide cements

OBJECTIVES: Calcium hydroxide cements have been largely used in deep cavities due to their abilities to stimulate dentin formation. However, their resistance can be relatively low and their solubility relatively high, in many instances. This study evaluated water sorption and solubility of different calcium hydroxide cements, in order to show alterations that may reduce their effectiveness. MATERIAL AND METHODS: Five discs (20 mm in diameter and 1.5 mm thick) of three different materials (Biocal®, Dycal® and Hidro C®) were prepared with the aid of a ring-shaped metallic matrix. After being stored at 37ºC for 24 h, the discs were weighed on a precision weight scale, dehydrated and weighed again. Immediately after weighing, discs were stored for a week in 50 mL of distilled water at 37ºC and, then, weighed again, dehydrated and submitted to a new weighing. The loss of soluble material and its water sorption was obtained from the difference between the initial and the final dry mass of each disc, after 1 week of immersion in water. Data were analyzed for significant differences by two-way ANOVA and Tukey's test (

Glass ionomer cements and their role in the restoration of non-carious cervical lesions

Glass ionomer based materials are clinically popular in several areas of restorative dentistry, but restoration of cervical lesions has proven particularly successful. Various etiologies, conformations, locations and structural characteristics make non-carious cervical lesions more challenging to adhesive restorative procedures and marginal seal in the long run. Due to their characteristics, glass ionomer cements (GICs) have precise indication for these cases. Moreover, the use of a GIC base underneath composite resin, the so-called "sandwich" or mixed technique, allows associating the good characteristics of composite resins and GICs, and has been considered quite useful in the restoration of non-carious cervical defects. The aim of this paper is to critically review the literature and discuss peculiar features of GICs regarding their role in the restoration of non-carious cervical lesions

Esthetic restoration of the smile: directly veneering a discolored anterior tooth

Case report: Even if directly veneering discolored anterior teeth with composite is quite widespread, proper reproduction of their natural appearance requires much from the professional. Comprehensive management, from planning to finishing and polishing, of a severely discolored upper central incisor through its directly veneering is critically reported. Relevance: Direct composite laminate veneers are, indeed, a viable treatment option to correct esthetic abnormalities involving most of the labial surface of anterior teeth. This relative conservative therapy, since accurately performed by the well qualified dentist, will assign the patient esthetic, functional and emotional rehabilitation, culminating in a harmonious and pleasant smile

Volumetric polymerization shrinkage of contemporary composite resins

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (;a; or = 0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87&plusmn;0.01) and Definite (1.89&plusmn;0.01) shrank significantly less than the other composite resins. SureFil (2.01&plusmn;0.06), Filtek Z250 (1.99&plusmn;0.03), and Fill Magic (2.02&plusmn;0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation

Resistência à tração diametral e sorção de água de cimentos de ionômero de vidro usados no Tratamento Restaurador Atraumático

The purposes of this study were to evaluate the diametral tensile strength and the water sorption of restorative (Fuji IX and Ketac Molar) and resin-modified glass-ionomer luting cements (ProTec Cem, Fuji Plus and Vitremer) mixed at both manufacturer and increased powder: liquid ratio, for their use in the Atraumatic Restorative Treatment. A conventional restorative glass-ionomer (Ketac Fil) was used as control. Specimens (6.0 mm in diameter x 3.0 mm in height) were prepared and stored (1 hour, 1 day and 1 week) for a diametral tensile strength test. Data were subjected to two-way ANOVA and Tukey tests (pAvaliou-se a resistência à tração diametral e a sorção de água de cimentos de ionômero de vidro restauradores (Fuji IX e Ketac Molar) e modificados por resina indicados para cimentação (ProTec Cem, Fuji Plus e Vitremer) manipulados na proporção pó: líquido indicada pelo fabricante e em maior proporção para a utilização no Tratamento Restaurador Atraumático. O ionômero restaurador convencional (Ketac Fil) foi utilizado como controle. Espécimes (6,0 mm de diâmetro x 3,0 mm de altura) foram preparados e armazenados (1 hora, 1 dia e 1 semana) para o teste de resistência à tração diametral. Os dados foram submetidos a ANOVA a dois critérios e ao teste de Tukey (

Maquete de Máquina de Ensaio Universal: Ferramenta de Ensino Odontológico sob a Óptica de um Aluno de Graduação

Ao iniciar o curso de Odontologia, os alunos se deparam com uma disciplina intitulada Materiais Dentários. Essa disciplina possui dificuldades inerentes ao ensino de partes de seu conteúdo, como as propriedades mecânicas dos materiais odontológicos. Tal fato se deve, provavelmente, à presença de uma linguagem própria e de conceitos mecânicos e físicos que fogem do cotidiano do aluno de graduação de Odontologia; somando-se a isso, temos um meio virtualizado onde esses alunos estão inseridos. Esse conjunto pode trazer dificuldades para a apreensão de conteúdo ao estudante, uma vez que existem diversas maneiras de assimilação de novas informações. O professor, portanto, deve compreender de onde advém a dificuldade dos alunos em apreender os conteúdos e então traçar estratégias para a melhoria do ensino. Assim, o objetivo do presente trabalho é expor como uma Maquete de Máquina de Ensaio Universal pode tornar inteligíveis conceitos abstratos das propriedades dos materiais dentários, permitindo o aprimoramento da compreensão de tais noções por parte dos alunos de graduação em Odontologia e o aperfeiçoamento do ensinoIn the beginning of the Dentistry course students take a subject called Dental Materials. This subject presents difficulties inherent to the content, like the mechanical properties of dental materials. This is probably due to the presence of a particular vocabulary and of mechanical and physical concepts that are far from the Dentistry student everyday; in addition to that these students are living in a virtual world. This set of characteristics can bring difficulties to student’s learning, once there are many ways to take in new information. Thus, the teacher must understand where does the students’ learning difficulty come from and create strategies to improve teaching. The purpose of this work is to expose how a Universal Testing Machine Model can make concepts of dental materials properties more intelligible, enhancing Dentistry graduation students’ learning, and also improving the teachin

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

Objective: This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods: Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: postsintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results: The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions: Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement