Repositório RCAAP

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

The removable partial prosthesis (RPP) is dispositive constructed with the objective of esthetical and functional rehabilitations of the teeth and absent tissues of patients partially edentulous. When confected for patients who lost posterior teeth uni or bilaterally, the distribution of mastigatory force is not equal, always occurring overstress in the direct pillar teeth. It have been demonstrated that the position of one dental implant in the region of second molar divide in a equanimity way the force and consequentially preserve the pillar teeth. In this way, this study objectived compare qualitatively, using the photoelastic method, the distribution of tensions and deformations in the structures of support of removable partial prosthesis with free extremity in conventional class II of Kennedy and associated with dental osseous intergraded implants with 2 different diameters. To this analyze was obtained three photoelastic models; one for conventional prosthesis, one for removable partial prosthesis associated with 3,75mm diameter implant and other for removable partial prosthesis associated with 5,00mm diameter implant. After the construction and adaptation of the prostheses in the models, an application of a statically force of 1,300kgf in the three photoelastic models obtained, was performed photography s of the models in a correct position in the polariscope for the qualitative analyze of tensions. The results demonstrated that the models with implants don t reductive the tensions in pillar teeth of RPP of free extremity and the implant of 5,00mm if diameter promoted the better distribution of tensions between teeth and implant.

Mestre em Odontologia

The aim of this study was evaluate the pulp vitality in vivo status after trauma comparing dental sensitivity tests with pulp vitality test. We studied 71 traumatized teeth, 79 vital teeth in the side of a group of forty patients treated at Program of Assistance to patients with Trauma Dento-Alveolar - Outpatient Reference of School of Dentistry, Federal University of Uberlandia in the period between 2005 and 2010. The pulp vitality status of teeth after trauma was assessed by three sensitivity tests: electrical, thermal heat and cold and a pulp vitality test using a pulse oximetry. After statistical tests with Pearson's correlation was significant correlation between sensitivity tests, both in traumatized teeth checked as the vital teeth in the side. There was no significant correlation between pulp sensitivity test and pulp vitality test. However, the oximeter alone showed a high percentage of diagnosis of pulp vitality.The results demonstrated that pulse oximetry was the test that was more efficient in assessing the pulp vitality status of teeth after trauma.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

The two biggest trends in surgical specialties are the minimally invasive surgery and computer-guided surgeries. In implantology, these two tendencies are translated into flapless surgery and implant insertion guided by computer. The most used way to transfer the virtual planning of dental implants to the surgical field is stereolithography guides. The aim of this study was to evaluate the accuracy of the transfer of virtual planning to surgical guides in implantology testing a new technique, which uses laboratory-fabricated surgical guides. Eighteen implants and their sleeves were virtually planned in six dried human mandibles based on CT images obtained in a cone-beam device. The transfer of this planning to the surgical guide was performed by a positioning tool of sleeves, which uses data generated by a specific software for Installing rings in surgical guides. A second CT was done of each surgical guide to check the final position of each ring. Comparing the virtual data with the real one made the evaluation of the transfer of virtual planning to the surgical guide. The difference between the planned and the final rings in linear measurements was 0.26 ± 0.16 mm in the buccolingual direction, 0.14 ± 0.12 mm in the mesiodistal direction, and 0.35 ± 0.39 mm in the vertical direction. In angular measures the difference between what was planned and what was actually done was 0.15 ± 0.36 ° in the buccolingual direction and 0.08 ± 0.39 ° in the mesiodistal direction. It was concluded that this new system allows the installation of sleeves in surgical guides precisely based on CT data.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Introduction: The immunohistochemical detection of nuclear β-Catenin has been widely used to demonstrate activation of the canonical Wnt/β- Catenin pathway in a wide variety of human cancers, including basal cell adenoma and basal cell adenocarcinoma salivary gland, although the immunolocalization of other proteins of this pathway is still unknown. The objective of this study was to access the immunolocalization of Wnt1, β-catenin and c-Myc in the basal cell adenoma and basal cell adenocarcinoma. Materials and Methods: We studied the immunolocalization of Wnt1, β-catenin and c-Myc in a series of four 28 basal cell adenoma and four basal cell adenocarcinoma, by immunohistochemistry using the streptavidin-biotin peroxidase method. Results: Wnt1 was positive in 14 cases (50.0%) always in a small proportion of cells, low intensity and restricted to the cytoplasm. β-Catenin was detected in the nucleus of tumor cells in all cases, being the prevalent pattern in 67.9% of them. In tumors with tubular differentiation, this finding was generally restricted to abluminal cells. C-myc was detected in 20 cases (71.4%) and it varied in proportion and intensity of tumor cells, always in cytoplasmic pattern. We could not identify any association between the expressions of these molecules in basal cell adenomas. Two recurrent cases showed high levels of Quickscore. For basal cell adenocarcinomas, the findings were similar, except that it was not common nuclear staining of β-Catenin. Conclusions: Our results confirm that the nuclear compartmentalization of β- Catenin is a feature of basal cell adenomas, which may be useful in their distinction to the basal cell adenocarcinoma. On the other hand, this feature cannot be due to activation of the canonical Wnt / β-Catenin, or at least the expression of its main agonist (Wnt1). Other agonists of this pathway remain to be investigated, such as Wnt3 and Wnt8. Similarly, the possible effect of the nuclear localization of β-catenin does not appear to be mediated by the expression of c-Myc.

Dental agenesis is one of the main anomalies of dental development therefore presents reflections on aesthetics and chewing. This study about the prevalence and hereditary behavior of agenesis of permanent teeth in the population of Uberlandia - MG, conducted with selected patients in 9407 trough radiographic exams of a particular radiological clinic from January 2006 to December 2007.The initial sample had 109 males and 145 females, totalizing 254 patients with at least one agenesis except for third molars, showed that 2,8% had agenesis without gender preference. The agenesis of the upper arch were represented by the lateral incisor isolated or both at the same time and in the lower arch, second premolars also separately or both. The upper agenesis showed predilection for females while the lower arch was the same for both genders. The study of hereditary behavior was conducted with the families of twenty-five patients from the initial sample who answered telephone calls about the presence of agenesis in the family. Ten patients denied and fifteen reported that some member of the family have agenesys and the informations were used to make individual heredrograms that suggested autossomal recessive pattern, showed that the repeats were significant in those who had agenesis of the upper lateral incisors with either one of two at the same time. Still suggests a possible stability in the inheritance of agenesis of maxillary lateral incisors that could be based on the study of molecular biology to determine the genetic markers.

This study evaluated surface roughness, topography and permeability of bovine enamel, by means of profilometer and scanning electron microscope (SEM), with and without silver nitrate solution, exposed to different bleaching agents. Fifty enamel samples were randomly divided into five groups (n=10): : PC16% Carbamide Peroxide 16% - Whiteness Perfect; PH6% - Hidrogen Peroxide 6% - White Class; PH35% - Hidrogen Peroxide 35% Whiteness HP Maxx; PC37% - Carbamide Peroxide 37% - Whiteness Super and C (control) wasn´t bleached and was kept in artificial saliva. For roughness analysis was used average surface rougness (Ra) and flatness coefficient (Rku) parameters. Topography and permeability observations were realized by mean SEM. For permeability evaluation samples were immersed in 50% silver nitrate solution and analysed using backscattered electron and secondary electron mode. For the roughness (Ra) evaluation Kruskal-Wallis and Wilcoxon Signed Ranks Test was used, and showed an increased on the surface roughness in all the bleachied group. The Rku parameter suggest changes on enamel integrity. The images obtained by SEM showed changes on the enamel topography and different penetrations in the silver nitrate immersed sample in the bleached group. It was concluded that different bleaching agents can alter the topography and the enamel surface roughness and the fact of silver nitrate have entered suggests area of easy penetration by oxygen.

The formation of biofilm and bacterial accumulation on dental materials may lead to the development of gingival inflammation and secondary caries. In dentistry different techniques can be used to make provisional restorations using acrylic polymethyl methacrylates (PMMA). The purpose of this study was to examine the effect of different surface finishing and polishing on surface roughness and the adhesion of S. sanguinis bacteria to PMMA. Fifty specimens (6mm diameter) were divided into 5 groups (n=5), following fabrication techniques and surface finishing and polishing: L (laboratorial fabrication and polishing), NF (Nealon technique and surface finishing), NP (Nealon technique and surface polishing), MF (technique recommended by manufacture and surface finishing), MP (technique recommended by manufacture and surface polishing). Five representative specimens were submitted to bacterial adhesion test and measured by counting with SEM images, two were observed the surface topography also by SEM images, other three were submitted to roughness test. Data were compared by ANOVA. The mean results of sample bacterial counts: NF: 19.6c; MP: 5.36ab; NP: 4.96ab; MF: 7.36b and L (control): 1.56a. The mean results of surface roughness: NF: 3.23d; MP: 0.52b; NP: 0.60b; MF: 2.69c and L (control): 0.07a (different letters means statistical significance difference). It was conclude that the laboratory processing of PMMA may decrease S.sanguinis adhesion and surface roughness, thus has a better prognosis in terms of periodontal health and less secondary caries.

Besides the differences in chemical composition, which has a direct influence on the mechanical properties of restorative materials, the various methods of evaluation have generated different results that make it difficult any comparison among their properties. The aim of this study was to determine and compare the flexural strength (FS) of four restorative materials and the influence of the measurement method in such property. Twelve groups (n=15) were obtained and each tested material (Filtek Z350, Epricord, Super Porcelain EX-3 and IPS Empress 2) was submitted to three mechanical tests to assess their FS. For three and four-point bending tests rectangular beams (25x2x2 mm) was used and disc-shaped (12x1,2 mm) was used in the biaxial test. Specimens were submitted to load at the 1 mm/min speed in an EMIC machine, the analysis of stress distribution was performed by 3D finite element analysis and fracture site was visually evaluated. Mean values of FS were obtained from the fracture load of the samples and subjected to statistical analysis. Two-way ANOVA and Tukey's test indicated significant differences between the materials with higher values for IPS Empress 2 (a), followed by Filtek Z350 (b) in all methods, followed by Super Porcelain EX-3 (c) and Epricord (d) in two of three tests. Three-point bending and biaxial tests showed significantly higher values (A), while the four-point bending test was inferior (B). Fracture modes observed correlated with the finite element analysis. Results indicated reliability of all methods, supported by reasonably low coefficients of variation and the highest values of the materials further strengthened in its composition. However, due to lower sensitivity, lower reproducibility (higher coefficient of variation) and greater difficulty of implementation, the four-point bending test seems to be less suitable.

Due to the difficulty of cleaning and comfort for the patient, some authors suggest that multiple adjacent implants are rehabilitated separately. The aim of this study was to evaluate the influence of the contact point in the success of adjacent implants compared with prosthetic rehabilitation on implants joined Morse taper. Photoelastic models were fabricated three implants with three Morse Taper 4.0 x 13.0 mm set straight, 2mm below the top edge of the model, straight line, varying the contact between the crowns and separated into 03 groups: Point Contact (PC) 1 mm diameter; Contact Surface (CS) 3mm diameter; splinted (ES), which was adapted fixed partial prostheses cemented Then the models were subjected to different types of loads: a = axial group (20N); b = lateral angle of 40° (20N) in the implant corresponding to the first molar, c = central axial (20N) in the implant corresponding to the second premolar. We obtained 30 images of each type of loading group (n = 30) in a circular polariscope. The values of fringe orders and maximum shear stress (&#964;) were obtained by the program Fringes by photoelastic analysis of 27 points in each image. We performed the Student t test with p <0.05 and calculate the area of graphics. The loads and lateral group had similar statistics gathering for the three groups (ES, PC, SC). In loading the central PC and ES groups had similar statistics, but were different statistically from the SC. Considering a general analysis, the ES group showed the best results for the stresses in the photoelastic model. Therefore, within the limitations of this study can conclude that splinting the crowns on multiple adjacent implants provided better biomechanical behavior for all types of loading. Groups PC, SC were the most susceptible to overload in the presence of side loading.

The success of alloplastic bone grafts is still limited because of inadequate osseointegration. In this study, TiO2 nanocrystals (21 nanometers) were synthesized by wet-chemical co-precipitation Their structure, size and purity were determined by Raman spectroscopy (RAMAN) and x-ray diffraction (XRD). Optical microscopy was used to evaluate inflammation arising from intraosseous implants in guinea pigs as recommended by the World Dental Federation (FDI). Ten guinea pigs were used receiving two implants each. Half of the guinea pigs were observed at four weeks and the rest at twelve weeks. 24 slides were prepared with 144 histological cuts, stained with hematoxylin-eosinand and analyzed for inflammation response by two independent observers. It was determined that inflammation was absent/mild at both time periods due to low cellular variability and direct and structural bone apposition on and around the material without visible separation or signs of rejection. These characteristics were observed in all samples. Nanotopography analysis and Atomic Force Microscopy (AFM) showed integration between the new bone and the implanted material. Therefore, through the methodology used, it was possible to evidence osseointegration and biocompatibility in alloplastic material at the nanoscale.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Leukoplakia is defined as a white lesion that is not removed by scraping and cannot be classified as any lesion, beyond it is not representing histopathological entity, because it can represent many epithelial maturation riots. The annual percentage of malignant transformation varies in different parts of the world, probably as a result of differences in tobacco and dietary habits. This work makes a retrospective, observational study in 76 patients who had been diagnosed with leukoplakia in the period 1996 to 2010 and with a minimum follow-up period of 12 months. Analysis of the sample showed no gender predilection, mean age 60.3 years and mean follow-up of 7.4 years. Smoking was found in 78% of patients. The new clinical evaluation showed that 18.7% of lesions disappeared, 31.2% did not change in size or appearance, 21.8% showed increase in the size or appearance, 3.1% showed a substantial regression of the lesion and 15,6% suffered malignant transformation. Among the patients who showed increase or appearance of lesions in other sites, 100% of them reported smoking in an average time of 32.5 years. Finally, in the five lesions that had undergone malignant transformation, 80% of them were present in smokers by an average of 35.5 years. Therefore, it is clear that the persistence of smoking is an important factor for the appearance of new lesions and malignant transformation of leukoplakia.

Peripheral nerve sheath tumors (PNST) are neoplastic or reactive diseases of rare occurrence in the oral cavity, whose diagnosis can be challenging. This study aimed to gather epidemiological and molecular information to improve biological characterization of PNST, favoring the differential diagnosis between them. After histological review, clinical and demographic data from TBNP evaluated between 1978 and 2010 by the Oral Pathology Laboratory of Federal University of Uberlândia, were organized, followed by immunohistochemical analysis of molecules S-100 and CD57. We found 29 cases (0.27% of total sample), corresponding to 6 traumatic neuromas (TN), 7 neurofibromas (NF), 7 schwannomas (SW), 5 granular cell tumors (GCT) and 4 palisaded encapsulated neuromas (PEN). There was no significant sex predominance, most patients were young adults, the tongue was the most affected anatomical site, and the tumors were usually asymptomatic. All tumors showed diffusely reactivity for S-100. Diffusely reactivity for CD57 was observed in TN, on rare parenchymal cells of SW and PEN, and none of them in NF. In addition, reactive nerve fibers permeated cases of NF, GCT and PEN, but not in SW cases. In conclusion, this study confirms the rarity of PNST in oral mucosa and clinical similarity between them, also the constant expression of S-100, demonstrating their probable shared origin. Finally, the observed rare or absent expression of CD57 shows that tumor s Schwann cells do not reach complete differentiation, but are found in GCT; moreover, the arrangement of nerve fibers may eventually be useful for diagnostic differentiation between different PNST.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais