Influência de protocolos adesivos simplificados na resistência ao cisalhamento de bráquetes ortodônticos

O objetivo deste trabalho foi avaliar in vitro a resistência ao cisalhamento de bráquetes ortodônticos metálicos. Para isto, foram utilizados três sistemas de fixação: resina convencional ortodôntica Transbond XT- 3M ESPE, cimento resinoso Rely-X U100-3M e resina Flow Filtek Z350 XT-3M ESPE. Foram selecionados 30 dentes bovinos recém-extraídos, com esmalte, sem defeitos e sem manchas. Os dentes foram limpos individualmente e armazenados em solução de timol 0,5% em temperatura ambiente por sete dias. Logo após, foram divididos aleatoriamente em 3 grupos, cada um com 10 dentes. Foi realizada profilaxia e em seguida escolhida a área mais plana do dente para fazer o condicionamento com ácido fosfórico a 37%, aplicação do adesivo selecionado e colagem do bráquete ortodôntico com o sistema de fixação selecionado. Utilizou-se um aparelho de luz led Radii (SDI) para fotoativar o sistema de fixação durante o procedimento da colagem. Em seguida, os dentes foram submetidos ao teste de resistência ao cisalhamento, em uma máquina eletrônica de ensaios eletromecânicos SHIMADZU AG-I, (10KN), com velocidade de pressão de 0,5mm/min e carga de ruptura registrada em Megapascal (MPa). Os resultados foram submetidos a estatística, utilizando análise de variância (ANOVA) e teste de Tukey ao nível de 5%de significância. Baseado nos resultados obtidos, os bráquetes apresentaram diferença adesiva de resistência ao cisalhamento. Pôde-se concluir que a resina ortodôntica transbond XT-3MESPE mostrou ser a mais resistente ao cisalhamento dos bráquetes ortodônticos

Influence of occlusal alterations on temporomandibular joint and mandibular growth : an animal model study

Orientador: Célia Marisa Rizzatti BarbosaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A cartilagem articular do côndilo mandibular é responsável pelo crescimento ósseo endocondral durante o desenvolvimento mandibular. Ela depende do funcionamento adequado da articulação temporomandibular (ATM) para sua diferenciação e maturação. Trabalhos demonstram que a manipulação funcional da mandíbula foi capaz de alterar a dinâmica fisiológica dessa cartilagem. Nesse sentido, a protrusão diminuiria a ação de cargas sobre o côndilo mandibular, estimulando o crescimento endocondral, e de forma inversa, a retrusão aumentaria a pressão sobre a cartilagem, inibindo o crescimento. Essas técnicas têm sido utilizadas com relativo sucesso na ortopedia facial com o intuito de corrigir discrepâncias maxilo-mandibulares. Entretanto, alguns quadros patológicos presentes nas ATMs podem alterar o seu desenvolvimento normal. Um dos fatores etiológicos que pode ser associado à presença de alterações no côndilo mandibular é a oclusão dental. A hipótese formulada é de que a presença de instabilidade ortopédica causada por um fator oclusal durante a fase de desenvolvimento pode levar à deficiência do crescimento mandibular e alterações intra-articulares. Assim, este trabalho teve por objetivo avaliar, em modelo animal, alterações da oclusão dental sobre o crescimento mandibular e tecidos intra-articulares. O estudo foi randomizado e cego. Foram utilizadas 40 ratas Wistar com 5 semanas de idade divididas aleatoriamente em 4 grupos com o mesmo número de animais: controle, com interferência oclusal, com ausência dos molares inferiores unilateral e com ausência dos molares inferiores bilateral. Os animais foram acompanhados por 8 semanas, período que correspondeu a sua fase de maturação óssea. Após esse período, os animais foram sacrificados e realizou-se tomografia computadorizada de feixe cônico (Cone beam) de suas cabeças para construção de protótipos de biomodelos, sobre os quais foram mensurados o comprimento da mandíbula, a altura do ramo mandibular e distância intercondilar. Em seguida, as articulações temporomandibulares foram cuidadosamente preparadas para análise imunohistoquímica dos níveis de colágeno tipo II, Fator de Crescimento Endotelial Vascular, e Interleucina 1? na cartilagem condilar. Os dados foram submetidos a análise estatística através do Software SPSS versão 17.0. As médias entre os grupos foram comparadas através do One-way Anova, enquanto as diferenças entre os lados da mandíbula foram avaliadas através do teste t de Student (?=0.05). A partir da análise dos resultados, observou-se que alterações oclusais podem afetar o desenvolvimento do osso mandibular, bem como alterar a expressão de Colágeno tipo II, Fator de Crescimento Endotelial Vascular e Interleucina 1? na cartilagem condilar. Diante do exposto, conclui-se que a oclusão dentária é capaz de interferir na dinâmica dos tecidos intra-articulares, sendo um fator importante durante o desenvolvimento craniofacialAbstract: The condylar cartilage regulates the endochondral ossification during mandibular development. Mechanical stimulus in the temporomandibular joint (TMJ) plays an important role in cell proliferation and differentiation of mandibular condyle. Studies have shown that functional mandibular displacement can affect TMJ cartilage dynamics. Mandibular advancement induces profound metabolic changes in the condyle and enhances growth. In contrast, mandibular retraction reduces growth. The overall picture emerging from the data is that unloading of the condyle increases growth, while loading reduces it. Therefore, dental occlusion could be one of the factors associated with the alteration of the TMJ growth. The hypothesis is that orthopedic instability caused by occlusal factors present during TMJ development can affect mandibular growth and intra-articular tissue. Thus, the purpose of this study was to evaluate the influence of dental occlusion on mandibular growth and intra-articular tissue in Wistar rats. The study was randomized and blinded. Forty 5 weeks old female Wistar rats composed the sample. The animals were randomly allocated to four groups with the same number of rats: (1) control, (2) occlusal appliance for functional posterior displacement of the mandible, (3) unilateral mandibular tooth extraction, (4) bilateral mandibular tooth extraction. The rats were sacrificed after 8 weeks, when they had achieved skeletal maturity. Immediately after death, the heads were fixed in 10% paraformaldehyde, and cone beam CT scan images were taken using the Classic I-CAT (Imaging Sciences International, Hatfield, PA, USA). The 3-dimensional images of rats' skulls were exported in multifile Digital Imaging and Communications in Medicine (DICOM) format, and acrylic rapid-prototyped templates of the mandibles were constructed for measurement of mandibular growth. Immunostaining was used for the detection of type II collagen, vascular endothelial growth factor (VEGF) and interleukin-1?. The data were processed with SPSS software (V 17.0 for Windows, SPSS Inc, Chicago, IL, USA). Differences among the groups were analyzed by one-way ANOVA (Tukey test as post-hoc test), while differences between sides were analyzed by non-paired Student's t test. Shapiro-Wilk and Levene tests were used to observe normality and variance homogeneity, respectively. Confidence level was set at 5%. The results of this study showed that dental occlusion is an important factor for the integrity of intra-articular tissues and to the healthy craniofacial development, emphasizing the importance of early treatment to normalize occlusion and create appropriate conditions for normal craniofacial developmentDoutoradoProtese DentalDoutor em Clínica Odontológic

Masticatory afficiency in denture wearers with bilateral balanced occlusion and canine guidance

The maintenance of masticatory function is especially important for patients wearing complete dentures due to their limitations. Thus, the bilateral balanced occlusal concept is used to achieve greater masticatory efficiency. However, a critical review of the literature reveals that there is not sufficient scientific evidence to support bilateral balanced occlusion as the most appropriate occlusal concept in complete dentures. Therefore, the aim of this study was to evaluate the masticatory efficiency in complete dentures wearers with bilateral balanced occlusion and canine guidance. A double-blinded controlled crossover clinical trial was conducted. The sample was composed by 24 edentulous patients who wore sets of complete dentures with both occlusal concepts during equal periods of 3 months. Objective data were collected through the masticatory efficiency test performed by the colorimetric method with the beads, in which capsules of a synthetic material enclosing fuchsine-containing granules were used. Subjective data were recorded by patient's ratings of their chewing function. No significant statistical difference was found for masticatory efficiency (p=0.095) between the two occlusal concepts studied. The results suggest that bilateral balanced occlusion does not improve the masticatory efficiency in complete denture wearers.A manutenção da função mastigatória tem importância especial em pacientes portadores de prótese total devido às limitações inerentes a esse tipo de prótese. Nesse contexto, a oclusão balanceada bilateral (OBB) é empregada com o intuito de obter-se uma maior eficiência mastigatória. Entretanto, analisando-se a literatura criticamente, observa-se que não existem evidências científicas suficientes que suportem a aplicação da OBB como conceito oclusal ideal em prótese total (PT). Assim, o presente trabalho teve o objetivo de verificar se pacientes portadores de PT dupla com OBB apresentam maior eficiência e capacidade mastigatória que aqueles com desoclusão com guia canino (DGC). Com esse intuito, realizou-se um ensaio clínico controlado duplo-cego do tipo crossover. A amostra foi composta de 24 pacientes portadores de prótese total dupla, onde todos fizeram uso de ambos os conceitos oclusais por períodos iguais de 3 meses. A avaliação da eficiência mastigatória foi realizada através do método colorimétrico com o uso de cápsulas mastigatórias. Não se encontrou diferença estatística significativa para a eficiência (p=0,0952) entre os dois conceitos oclusais estudados. Dessa forma, pode-se concluir que usuários de PT dupla com OBB não apresentam maior eficiência mastigatória que aqueles com DGC

Masticatory Efficiency In Denture Wearers With Bilateral Balanced Occlusion And Canine Guidance.

The maintenance of masticatory function is especially important for patients wearing complete dentures due to their limitations. Thus, the bilateral balanced occlusal concept is used to achieve greater masticatory efficiency. However, a critical review of the literature reveals that there is not sufficient scientific evidence to support bilateral balanced occlusion as the most appropriate occlusal concept in complete dentures. Therefore, the aim of this study was to evaluate the masticatory efficiency in complete dentures wearers with bilateral balanced occlusion and canine guidance. A double-blinded controlled crossover clinical trial was conducted. The sample was composed by 24 edentulous patients who wore sets of complete dentures with both occlusal concepts during equal periods of 3 months. Objective data were collected through the masticatory efficiency test performed by the colorimetric method with the beads, in which capsules of a synthetic material enclosing fuchsine-containing granules were used. Subjective data were recorded by patient's ratings of their chewing function. No significant statistical difference was found for masticatory efficiency (p=0.095) between the two occlusal concepts studied. The results suggest that bilateral balanced occlusion does not improve the masticatory efficiency in complete denture wearers.21165-

The Influence Of Double Flask Investing On Tooth Displacement In Dentures Processed By Microwave Irradiation.

This study evaluated the influence of the bimaxillary flask (BMF) and two different investing materials on first molar inclination in dentures processed by microwave irradiation. The BMF may minimise tooth displacement, saving time and improving occlusion. Forty pairs of dentures were randomised into four groups: stone wall in monomaxillary flask; silicone wall in BMF; stone wall in BMF; acrylic resin retentions and silicone in BMF. Dentures were processed by microwave irradiation. Two referential points were established on tooth surface. A microscope and a digital pachymeter were used to measure the distance between these points, and the angles α (right maxillary molar), β (left maxillary molar), α' (right mandibular molar) and β' (left mandibular molar) were calculated by the law of cosines. Data were submitted to Kruskal-Wallis (5% significance). No difference was observed among the groups (p > 0.05). In the intra-group analysis, α was significantly different for groups I, II and III; α', for groups II and IV; β, for all groups; β', for groups III and IV. First molar inclination was similar for monomaxillary and BMFs. The use of stone or silicone as investing materials presented the same effect on tooth inclination.29e924-

Reproducibility of a silicone-based test food to masticatory performance evaluation by different sieve methods

The aim of this study was to evaluate the reproducibility of the condensation silicone Optosil Comfort® as an artificial test food for masticatory performance evaluation. Twenty dentate subjects with mean age of 23.3 ± 0.7 years were selected. Masticatory performance was evaluated using the simple (MPI), the double (IME) and the multiple sieve methods. Trials were carried out five times by three examiners: three times by the first, and once by the second and third examiners. Friedman’s test was used to find the differences among time trials. Reproducibility was determined by the intra-class correlation (ICC) test (α = 0.05). No differences among time trials were found, except for MPI-4 mm (p = 0.022) from the first examiner results. The intra-examiner reproducibility (ICC) of almost all data was high (ICC ≥ 0.92, p < 0.001), being moderate only for MPI-0.50 mm (ICC = 0.89, p < 0.001). The inter-examiner reproducibility was high (ICC > 0.93, p < 0.001) for all results. For the multiple sieve method, the average mean of absolute difference from repeated measurements were lower than 1 mm. This trend was observed only from MPI-0.50 to MPI-1.4 for the single sieve method, and from IME-0.71/0.50 to IME-1.40/1.00 for the double sieve method. The results suggest that regardless of the method used, the reproducibility of Optosil Comfort® is high.010

Selection of mandibular major connector based on a conventional impression technique

The selection of the mandibular major connector of a removable partial prosthesis depends on the distance between the floor of the mouth and free gingival margin, height of the lingual frenum, presence of mandibular tuberosity, mobility of anterior teeth, major connector used in a previous denture and patient′s opinion, slope and retentivity of alveolar bone. However, the dental technician rather than the dentist often selects the major connector in the cast model. Aim : To determine whether there is a difference between selecting the mandibular major connector clinically or in the cast model as determined by a conventional impression technique using alginate and a universal metallic tray. Methods: The sample was composed of 64 patients under treatment at the Department of Dentistry of the Federal University of Rio Grande do Norte. The distance between the floor of the mouth and the free gingival margin of the remaining elements was measured with a millimeter periodontal probe in the oral cavity and in the cast models. Results: The mean clinical distance between the free gingival margin and the floor of the mouth was 7.39 ± 2.13 mm, in contrast to the mean distance found in the models (9.03 ± 1.36). The Mann-Whitney test showed a significant difference (p < 0.001) between the two measures. Conclusions : For the adequate selection of the mandibular major connector, the distance between the gingival margin and the floor of the mouth must be measured clinically when using the conventional impression technique

Selection of mandibular major connector based on a conventional impression technique

ection of the mandibular major connector of a removable partial prosthesis depends on the distance between the floor of the mouth and free gingival margin, height of the lingual frenum, presence of mandibular tuberosity, mobility of anterior teeth, major connector used in a previous denture and patients opinion, slope and retentivity of alveolar bone. However, the dental technician rather than the dentist often selects the major connector in the cast model. Aim: To determine whether there is a difference between selecting the mandibular major connector clinically or in the cast model as determined by a conventional impression technique using alginate and a universal metallic tray. Methods: The sample was composed of 64 patients under treatment at the Department of Dentistry of the Federal University of Rio Grande do Norte. The distance between the floor of the mouth and the free gingival margin of the remaining elements was measured with a millimeter periodontal probe in the oral cavity and in the cast models. Results: The mean clinical distance between the free gingival margin and the floor of the mouth was 7.39 ± 2.13 mm, in contrast to the mean distance found in the models (9.03 ± 1.36). The Mann-Whitney test showed a significant difference (p < 0.001) between the two measures. Conclusions: For the adequate selection of the mandibular major connector, the distance between the gingival margin and the floor of the mouth must be measured clinically when using the conventional impression technique