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Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive.ObjectiveThe aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization.Material and methodsSixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05).ResultsThe control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa).ConclusionAll repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength.

The liquid lubricant used in this study does not influence the stability of Y-TZP single-implant restorations.

No abstract

The majority of cases showed that horizontal and vertical measurements of the face cannot be used as a reference for determining the morphology of the maxillary central incisor crown. It is relevant to analyze and compare other morphological structures to improve the oral health-related quality of life for the conventional denture wearer.

Neste trabalho foram analisadas as possíveis alterações promovidas pela incorporação de agentes desinfetantes na resistência à compressão, estabilidade dimensional linear e resistência à tração diametral de modelos em gesso. As amostras foram confeccionadas em gesso pedra tipo III e divididas nos seguintes grupos: Grupo 1- controle (espatulado de acordo com as recomendações do fabricante); Grupo 2- adição de 0,5 % de hipoclorito de cálcio; Grupo 3- adição de 1,0 % de hipoclorito de cálcio; Grupo 4- adição de 1,5 % de hipoclorito de cálcio. Baseado nos resultados obtidos pode se observar que a incorporação de hipoclorito de cálcio influenciou negativamente nos valores de resistência a tração diametral do gesso avaliado, aspecto também observado na resistência a compressão com a incorporação de hipoclorito de cálcio 1,5%. A análise da estabilidade dimensional demonstrou que o agente desinfetante promoveu uma diminuição na expansão de presa apresentada pelo gesso. Com isso, concluímos que a incorporação de hipoclorito de cálcio promove uma tendência à diminuição da expansão apresentada durante a presa do gesso, porém esta incorporação acarreta uma diminuição na resistência dos modelos de gesso.

Influence of surface treatments on the flexural strength of denture base repairObjective: The purpose of this study was to evaluate the flexural strength of repairs made with autopolymerising acrylic resin after different treatments of joint surfaces. Material and Methods: Fifty rectangular specimens were made with heat-polymerised acrylic resin and 40 were repaired with autopolymerising acrylic resin following joint surface treatments: group 1 (intact specimens), group 2 (chemical treatment: wetting with methyl-methacrylate for 180 s), group 3 (abraded with silicon carbide paper), group 4 (abraded and wetting with methyl-methacrylate for 180 s) and group 5 (without surface treatment). The flexural strength was measured by a three-point bending test using a universal testing machine with a 100 Kgf load cell in the centre of repair at 5 mm/min cross-head speed. All data were analysed using one-way ANOVA and Tukey HSD test for multiple comparisons (p < 0.05). Results: Among repaired specimens, groups 2 and 4 had 66.53 ± 3.4 and 69.38 ± 1.8 MPa mean values and were similar. These groups had superior flexural strength than groups 3 and 5 that were similar and had 54.11 ± 3.4 and 51.24 ± 2.8 MPa mean values, respectively. Group 1 had a mean value of 108.30 ± 2.8 MPa being the highest result. Conclusion: It can be concluded that the treatment of the joint surfaces with methyl-methacrylate increases the flexural strength of denture base repairs, although the strength is still lower than that observed for the intact denture base resin. Abrasion with sandpaper was not able to influence the flexural strength of repaired denture bases.

INTRODUÇÃO 1 2 REVISÃO DA LITERATURA 7 2.1-Complicações em Próteses Sobre Implantes 9 2.2-A estabilidade da união parafusada: Uma análise biomecânica e comportamental dos parafusos. 14 2.3-O abutment UCLA 41 2.4-Podem os parafusos permanecer sempre apertados? Como evitar o afrouxamento dos parafusos. Interpretação dos autores. 44 3 PROPOSIÇÃO 47 4 MATERIAL E MÉTODOS 51 4.1-Dispositivo de avaliação dos graus de rotação dos parafusos 53 4.2-Implantes e componentes protéticos 56 4.3-Confecção dos corpos de prova 57 4.3.1-Inclusão, fundição, desinclusão e acabamento dos corpos de prova 60 4.4-Análise por meio de Microscopia Eletrônica de Varredura (MEV) 63 4.4.1-Teste EDS (Espectrometria de Energia Dispersiva de Raios-X) 64 4.5-Teste laboratorial 64 4.5.1-Funcionamento do dispositivo 67 4.6-Análise estatística 70 vi 5 RESULTADOS 5.1-Momento de Torque 5.2-Momento de Re-torque 5.3-Destorque 5.4-Comparação entre ensaios-Momento de Torque 5.5-Comparação entre ensaios-Momento de Re-torque