Photoelastic stress analysis of different attachment systems on implant-retained and conventional palatal obturator prostheses.

BACKGROUND: Considering that an increasing number of patients are victims of mutilator surgical resections, these studies are important for treatment success of rehabilitation of patients presenting oronasal communication. PURPOSE: The aim of this study was to assess the stress distribution through photoelasticity in palatal obturator prostheses with different attachment systems for implants. METHODS: Two photoelastic models were obtained from an experimental maxillary model presenting an oronasal communication. One model was fabricated without implant, and the other with 2 implants 10 mm in length inserted in the left crest. Four colorless palatal obturator prostheses were fabricated. One prosthesis presented no attachment system, whereas the remaining prostheses were adapted to 3 attachment systems. The assembly was positioned in a circular polariscope for application of axial load. RESULTS: The results were based on photographic records of stress in the photoelastic model submitted to loading. The records revealed higher stress concentration on the bar-clip system followed by the O'ring/bar-clip and O'ring systems, respectively. A homogeneous stress distribution was observed on the photoelastic model with the mucous-supported prosthesis. CONCLUSIONS: The attachment systems generated different characteristics of stress distribution that was concentrated surrounding the implants. The bar-clip system exhibited the highest stress concentration on the alveolar crest.

Photoelastic analysis of implant-retained and conventional obturator prostheses with different attachment systems and soft relining.

Complete and partial loss of maxillary bone may jeopardize oral physiology and generate complications as oral-sinus-nasal communication. Palatal obturator prostheses are a treatment alternative for rehabilitation of these patients. The aim of this study was to assess stress distribution, through photoelasticity, on palatal obturator prostheses associated with different attachment systems (o'ring, bar clip, and o'ring/bar clip) of implants and submitted to relining. Two photoelastic models were fabricated according to an experimental maxillary model with oral-sinus-nasal communication. One model did not present implants, whereas the other included 2 implants with 13.0 mm in length in the left ridge. Four colorless maxillary obturator prostheses were fabricated and relined with soft silicone. One of these prostheses presented no attachment system, whereas the remaining prostheses included attachment systems adapted to the implants. The assembly (model/attachment system/prosthesis) was positioned in a circular polariscope during loading with 100 N at 10 mm/s. The results were based on observation during the experiment and photographic records of stress on the photoelastic model. The bar clip system exhibited the highest stress concentration followed by o'ring/bar clip and o'ring systems. The attachment systems presented different stress distribution with greater concentration surrounding the implants and homogenous stress distribution on the photoelastic model without implants. The highest concentration of fringes occurred, in ascending order, with o'ring, o'ring/bar clip, and bar clip systems.

Relationship between psychological factors and symptoms of TMD in university undergraduate students

Temporomandibular disorders is a collective term used to describe a number of related disorders involving the temporomandibular joints, masticatory muscles and occlusion with common symptoms such as pain, restricted movement, muscle tenderness and intermittent joint sounds. The multifactorial TMD etiology is related to emotional tension, occlusal interferences, tooth loss, postural deviation, masticatory muscular dysfunction, internal and external changes in TMJ structure and the various associations of these factors. The aim of this study was to evaluate the prevalence of the relationship between signs of psychological distress and temporomandibular disorder in university students. A total 150 volunteers participated in this study. They attended different courses in the field of human science at one public university and four private universities. TMD was assessed by the Research Diagnostic Criteria (RDC) questionnaire. Anxiety was measured by means of a self-evaluative questionnaire, Spielberger's Trait-State anxiety inventory, to evaluate students' state and trait anxiety. The results of the two questionnaires were compared to determine the relationship between anxiety levels and severity degrees of chronic TMD pain by means of the chi-square test. The significance level was set at 5%. The statistical analysis showed that the TMD degree has a positive association with state-anxiety (p=0.008; p<0.05) and negative with trait-anxiety (p=0.619; p<0.05). Moreover, a high TMD rate was observed among the students (40%). This study concluded that there is a positive association between TMD and anxiety.

Disfuncao temporomandibular e o termo usado para descrever uma serie de disturbios envolvendo as articulacoes temporomandibulares, musculos da mastigacao e oclusao, com sintomas comuns como dor, restricao de movimento, sensibilidade muscular e ruido articular intermitente. A etiologia da DTM e multifatorial e esta relacionada a tensao emocional, interferencias oclusais, perda de dentes, desvio postural, disfuncao muscular mastigatoria, mudancas internas e externas na estrutura da ATM, e a diferentes associacoes entre esses fatores. O objetivo deste estudo foi avaliar a relacao entre estresse psicologico e sinais de desordem temporomandibular em estudantes universitarios. Um total de 150 voluntarios participaram deste estudo sendo alunos de uma universidade publica e quatro universidades privadas de diferentes cursos da area de ciencias humanas. A avaliacao da DTM foi realizada por meio do questionario Research Diagnostic Criteria (RDC). Para a avaliacao da ansiedade foi aplicado o questionario Ansiedade Traco-Estado de Spielberger. Os resultados dos niveis de ansiedade e dos graus de DTM dos dois questionarios foram comparados pelo teste do qui-quadrado, com nivel de significancia de 5%. A analise estatistica mostrou que o grau de DTM tem relacao positiva para a Ansiedade-Estado (p = 0,008, p <0,05) e negativa para a ansiedade-traco (p = 0,619, p <0,05), alem disso, foi observado alto indice de DTM entre os estudantes (40%). Por meio dos resultados obtidos e analisados neste estudo, concluiuse que havia uma associacao positiva entre DTM e ansiedade.

Evaluación de la dureza shore a en dos técnicas de impresión con siliconas por condensación bajo la influencia del uso de desinfección química por impresión con solución de clorhexidina al 2 por ciento / Evaluation of hardness in two impression techniques with condensation silicones under influence chemical disinfection with clorhexidine 2 percent

Las siliconas de polimerización por condensación, actualmente, son muy utilizadas en el mercado odontológico. Debido a este hecho, nuestro objetivo fue estudiar la dureza Shore A de dos siliconas de condensación (Zetaplus - Zhermark y Clonage - DFL), simulando dos técnicas de impresión (densa y densa + fluida) bajo la influencia de desinfección química con solución a base de clorhexidina al 2 por ciento (aspersión por 5 minutos). Fueron confeccionados 56 muestras, a partir de matrices metálicas, divididos en 4 grupos para cada técnica de impresión, siendo la mitad de las muestras de cada técnica sometidas a desinfección química. El Test de dureza fue realizada por medio de un durómetro (modelo GSD 709) de acuerdo con las especificaciones D-2240 de la Sociedad Americana para Prueba y Materiales (ASTM), los resultados obtenidos, fueron analizados por medio del Test de análisis de varianza y al Test de Tukey (p<0,05). Se concluyó, que para cualquier condición experimental estudiada se encontró diferencia estadísticamente significativa cuando se analizaron los valores medios de desinfección química, tipo de material y técnica utilizada

Elastomerics materials currently represent a major choice in the dental market as an impression material. The aim of this study was to asses Shore A hardness of two condensation silicones (Zetaplus - Zhermack and Clonage - DFL) using two impression techniques (putty and putty/wash) under influence of chemical disinfection with clorhexidine spray to 2 percent (for five minutes). Fifty-six specimens were made in metallic matrices, subdivided in 4 groups for each impression technique; half of each technique was submitted to chemical disinfection. Hardness test was performed with a durometer (GSD 709) according ASTM specifications (D-2240), the results were submitted to analyses of variance (ANOVA) and Tukey’s test (p<0.05). It was concluded that for all experimental condition, difference statistically significant was found