Estudo sobre o uso do pentacloreto de nióbio, como ácido de Lewis, na síntese de enaminas através da reação de adição de Michael

The NbCl5 being a strong electrophile, is a potential candidate to act as a Lewis acid, and therefore it mediates various organic reactions. For this reason, it has received continuous attention by Brazilian researchers, especially in recent decades, since Brazil holds the largest reserves of niobium, besides being the largest producer of this element. The Michael addition reaction is one of the most widely used for forming carbon-carbon bonds and takes place by the addition of nucleophiles to activated olefins. Although this type of reaction is usually catalyzed by base, there are reports in the literature on the use of various Lewis acids in this type of reaction. The synthesis of enamines based acetilenodicarboxilates and amines, aromatic or alkyl, by Michael addition reaction is quite interesting, since these are valuable synthetic intermediates for the synthesis of heterocyclic and they are used in multicomponent reactions. The derivatives of anilino-fumarate also have a great potential for medical application. In this study we investigated the use of niobium pentachloride as Lewis acid to catalyze the Michael additions between the derivatives of aniline and acetilenodicarboxilates the synthesis of enamines

Efeito do recobrimento de filmes de carbono tipo diamante depositados a plasma na manutenção do torque de parafusos protéticos

Pós-graduação em Odontologia Restauradora - ICT

Infiltração bacteriana nas interfaces entre implantes e pilares: efeito do desenho das conexões protéticas

Pós-graduação em Odontologia Restauradora - ICT

Avaliação da integração de implantes de silicone com superfícies lisa, texturizada e de poliuretano em cavidades anoftálmicas evisceradas de coelhos

Pós-graduação em Bases Gerais da Cirurgia - FMB

Cimentação de coroas com fosfato de zinco sobre munhões de liga de titânio, irradiados ou não por laser

By means of tensile strength, NiCr total crowns were removed from machine-made conical abutments composed by an Ti-6Al-4V alloy. In a total of 20 abutments, 10 were used with it surface presenting high smoothness and 10 abutments had its surfaces modifi ed by laser both cemented with zinc phosphate. The mechanical test was performed at a MTS 810 universal machine adjusted to a speed of 0.5 mm/m. The statistical analysis was done by Levene’s test, which showed homogeneity of variances among groups (F =2.21; p < 0.1). “Student t test” showed that signifi cant differences were found between groups. The modifi cation of the abutment surface through laser caused an increase in pull-out resistance of crowns cemented with zinc phosphate from 430.66 N to 1.514,87 N.

Implantes nanotopograficamente modificados pela ação do laser Yb-YAG

Titanium has proven its suitability as an implant material in surgery over many years. Excellent biocompatibility and corrosion resistance are outstanding features. Implant surfaces always causes concern and interest in scientific communities, due to its close relationship with the time required for osseointegration. Surface modification can be performed by several methods, being laser irradiation one of them. Titanium implants with two different surfaces were inserted in rabbits: Group I (G-I: machined surface, control group), and group II (G-II: laser irradiated, test group) being processed 30 and 60 days after surgery for histological analysis. Surface characterization was performed with SEM-EDS, contact angle measurement, and mean roughness (Ra) parameters. Surface analysis in the GII group showed a nanomorphology affected by melt and quick solidification zones following laser irradiation (SEM), as well as total wettability and Ra mean values significantly higher than in the G-I group. The laser treatment resulted in a homogenized, porous surface, with increased surface area and volume. Histological analysis of bone-implant contact linear extension (BIC) showed better results in G-II at 30 days (39.26 ± 18.23 and 68.41 ± 13.68 for G-I and G-II groups, respectively). Titanium implants modified by laser irradiation showed important features that may accelerate early osseointegration.

Implantes dentais em pacientes com diabetes mellitus

Dental implants represent a great improvement in Dentistry in respect to rehabilitation of edentulous ridges due to the functional and aesthetic reestablishment with long-term predictability and success. However, the effectiveness of this treatment relies on successful osseointegration during the healing period. In this way, the applicability of dental implants in patients with diabetes mellitus (DM) remains controversial, by the fact that the hyperglycemic status presents a negative effect on the osseointegration. It is not clear yet if the therapy with dental implants is an absolute contraindication to these patients. For this reason, the aim of the present study is to review the literature about the treatment with dental implants in patients with diabetes and to propose a protocol to perform dental implants in patients with diabetes. Diabetes has been considered a relative contraindication to dental implants, as the patients with adequate metabolic control can be treated with this kind of therapy, because inadequate metabolic control can lead to the failure of the treatment. Besides, there are risk factors for the diabetic implant patient that may decrease the success rates of dental implants therapy. In this way, the dentist should understand all the relevant implications before considering the indication of dental implants to patients with diabetes. It is important to have more controlled studies to evaluate the effects of diabetes on the implant-tissue interface and further investigations are necessary in order to elucidate the role of insulin and molecular mechanisms that might interfere on the osseointegration in patients with diabetes.

Protocolo mandibular com implantes curtos

Jaws atrophy represents a great challenge to Implantology regarding rehabilitation of edentulous areas. This paper reports an extreme mandibular atrophy with only 9mm of height between the mental foramina. In these situations, treatment options include bone augmentation techniques, transmandibular, or short dental implants. It is well accepted that bone grafts to improve height do not have good predictability. Besides, osteogenic distraction is associated with a great patient discomfort and transmandibular implants are related with high failure rates. Also, surgical-prosthetic rehabilitations with short dental implants had been associated to good success rates. The purpose of this clinical case is to report a severe mandibular atrophy, successfully treated with four short dental implants between mental foramina for implant-supported prosthesis.

Estudo prospectivo sobre a utilização de próteses totais implantossuportadas em pacientes edêntulos

The objective of this study was to evaluate the impact of replacing conventional mandibular complete dentures by complete fixed dentures on the oral health-related quality of life and kinesiographic parameters of maxillary edentulous patients. Material and Methods: edentulous patients (n = 16) received one set of new complete dentures and after the intraoral adjustments and adaptation period (30 days), the Brazilian version of Oral Health Impact Profile for assessing edentulous subjects (Ohip-Edent) was used to evaluate the oral health-related quality of life (OHQOL) of the participants. Additionally, the kinesiograph instrument K6-I (Myotronics Research Inc., Seattle, WA) was used to record opening and closure range of movement, mandibular movement, and the pattern of maxillary complete denture movement on chewing. Afterwards, the patients had their mandibular complete dentures replaced by a complete fixed denture and the same evaluation protocol was performed after 3 and 6 months. Ohip-Edent responses were analyzed using Wilcoxon's test for repeated measures (α = .05) and Kinesiographic data using the Student´s t test (α = .05). Results: The Ohip-Edent showed an improvement of general oral health-related quality of life after 3 and 6 months of the treatment with complete fixed dentures. Kinesiographic recordings revealed a significant increase on maximum mandibular movements of vertical opening and no differences for the movement of the maxillary complete denture on chewing after treatment with complete fixed dentures was observed. Conclusion: the installation of complete fixed dentures improved the OHQOL and changed mandibular movements, with increases in vertical amplitude of maximal opening.

Prótese metalocerâmica associada à prótese metaloplástica implantossuportada em paciente desdentado total

The use of different methods and materials should be considered during the planning of implant-supported prostheses. Complications such as fractures of the acrylic resin base, wear and fracture of teeth can occur frequently, creating the need for careful planning for each patient, which can make the selection of the type of treatment more complex. Thus, this article describes the oral rehabilitation of a completely edentulous patient with bimaxillary fixed implant-supported prosthesis, with complaints on aesthetics, loss of vertical dimension and fracture of acrylic resin teeth of the upper arch. After the restoration of vertical dimension, his dentures were replaced with new bimaxillary implant-supported fixed prostheses, ceramic and acrylic resin were used as veneering material for maxilla and mandible, respectively. At the end of the treatment, the patient received bimaxillary flat occlusal splints to protect the teeth and implants of possible parafunctional habits. The approach for the treatment allowed a quick and effective resolution, with aesthetic and functional outcomes very favorable for the patient.

Influência do desenho do implante na micromovimentação de implantes imediatos com carga imediata: análise multivariada em elementos finitos

The purpose of this paper was to evaluate the influence of different implant designs on the micromovements of immediately placed implants. CT-based finite element models comprising an upper central incisor socket and four commercially available internal connection implant designs (SIN SW®, 3i Certain®, Nobel ReplaceTM, and RN synOcta® ITI Standard) of comparable diameter and length were constructed. 50, 100 and 200N magnitude loads were applied over the implant. ANOVA at 95% level of significance was used to evaluate bone to implant relative displacement (micromovements). The implant design (68,80%) greatly influences the micromovement of immediately placed implants. However, the loading magnitude (68,80%) is the most important factor regarding the implant stability in this protocol.

Implantes curtos revisão da literatura

The contemporary implant dentistry is in constant technological development, improving the oral rehabilitation process of partial or totally edentulous patients. On the other hand, anatomical limitations, such as the maxillary sinus and the mandibular canal in the posterior region of the jaws can limit the implant placement. Furthermore, due to the absence of dental elements, alveolar ridge atrophy is frequently observed. This aspect represents a loss either in quantity or quality of the bone tissue available for the dental implant rehabilitation. To make possible the dental implant rehabilitation even in adverse conditions, some solutions have been considered, such as the use of short implants (≤ 10 mm length) and/or small diameter implants (2,8; 3,3 and 3,5 mm width). The aim of this study is to present a literature review considering the use of short implants in oral rehabilitation, presenting the currently view of the matter. Based on the literature review, the use of short implants produced similar clinical success to conventional implants (greater than 10 mm in length). Therefore, its use can be considered a viable alternative, where anatomical limitations are present.

Aspectos biológico-celulares da osseointegração baseados nas superfícies de implantes

Osseointegration involves a cascade of biological events, which can be accelerated by modifying the micro and/or nanometric topography of dental implant surfaces. Considering that different treatment types modify the titanium surface giving it a more pronounced rough topography, and physicochemical changes that appear to positively influence the osseointegration process, a literature review was made on the main types of surface treatments and their influence on the biological and cellular aspects of osseointegration, with publications dating from 1969 until the present moment. Although the precise role of the implant surface on the osseointegration of dental implants is not completely clear, the specific effects of implant surface on bone regeneration, initial kinetics, and evolution of mechanical properties have shown to be quite promising. Thus, based on dental implant surface modifications, osseointegration can be defined as a process by which rigid asymptomatic fixation of an alloplastic material can be achieved and kept in close contact with bone tissue, being resistant to early and late functional loads. This process can be modulated by an appropriate treatment of the alloplastic material surface.

Comportamento biomecânico do sistema prótese/implante em região anterior de maxila: análise pelo método de ciclagem mecânica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo comparativo in vitro da resistência à remoção de grampos circunferenciais aplicados sobre dentes íntegros e restaurados com resina composta

An experimental study was undertaken in arder to find out lhe behavior of the required force to yield dislodgement of circumierential clasps of removable partial dentures ou two groups of samples. 1 with retentive terminais engaging and acting ou enamel 2 with retentive terminais engaging on enamel and acting on composite resm With this aim a device was designed based on a sewing machine (brand name Elgin) that could repeatedly simulate lhe introduction-removal movement of circunferencial clasps ou the samples. ln addiction the device had a platform to sustain the samples and permit measurements, a cycle counter and a dynamometer. The samples were constructed by inclusion in dental stone of extracted natural molar teeth whose retentive areas were ou natural enamel or composite resin addictions.The clasps were fabricated from wax ups of resin and wax and were cast with chromium cobalt alloy. The composite resin used was one of the last generation, monomodal type, photopolymerized and binded to the enamel by the acid etching technique. Tests were carried out in aqueous enviroment. Is was established a maximum of 5.000 cycles for each of the samples. Observatins were made from 100 to 100 cycles until 2.000 and from 200 to 200 cycles to 5.000. Results showed that variations in the amount of the required force for dislodgement of the clasps from the samples during the test periods had no significancy eather to those with retentive areas on the enamel or to those with retentive fabricated with addictions of composite resin