Effect of Accelerated Aging on the Sorption and Solubility Percentages of Silicone Facial Prostheses.

OBJECTIVE: This study aimed to evaluate the effect of accelerated aging on the sorption and solubility percentages of the MDX4-4210 and A-2186 silicones. MATERIALS AND METHODS: Two silicones (A-2186 and MDX4-4210) and three intrinsic pigments (bronze, black, and pink) were used in this study. Thus, six groups were created (n = 10): Group 1 = bronze MDX4-4210; Group 2 = black MDX4-4210; Group 3 = pink MDX4-4210; Group 4 = bronze A-2186; Group 5 = black A-2186; and Group 6 = pink A-2186. The dimensions of all samples were the same (45-mm diameter (ø) × 1-mm thickness). The samples were aged for a total of 1,008 hours. In this period of 1,008 hours of accelerated aging, the sorption and solubility percentages of each sample were calculated at three time points (252, 504, and 1,008 hours). STATISTICAL ANALYSIS: Three-way analysis of variance (ANOVA) and the Tukey test were performed (α = 0.05). RESULT: Accelerated aging can significantly increase the sorption and solubility percentages of the MDX4-4210 and A-2186 silicones.

Influence of Different Pigment Incorporation Methods on the Sorption and Solubility of Medical Silicones.

OBJECTIVE: The aim of this study is to verify the influence of three pigment incorporation methods (conventional, mechanical, and industrial) on the sorption and solubility of the MDX4-4210 and A-2186 silicones. MATERIALS AND METHODS: The groups formed were based on the silicones used (A-2186 and MDX4-4210), intrinsic pigments (pink, bronze, and black), and pigment incorporation methods (conventional, mechanical, and industrial). The dimensions of all samples were 45-mm diameter (ø) × 1-mm thickness. Readings were taken initially and after 1,008 hours of aging. STATISTICAL ANALYSIS: Three-way analysis of variance and the Tukey's test were performed (α = 0.05). RESULTS: For sorption and solubility, there was no difference between the incorporation methods for the A-2186 silicone, regardless of the pigment used (p > 0.05). For pink MDX4-4210, the industrial and mechanical methods showed higher values of sorption compared with the conventional method (p < 0.05). For bronze MDX4-4210, the industrial method showed a higher sorption value compared with the conventional and mechanical methods (p < 0.05). For black MDX4-4210, there was no difference between incorporation methods based on sorption (p > 0.05). For pink MDX4-4210, the mechanical method showed a higher solubility value compared with the industrial and conventional methods (p < 0.05). For black MDX4-4210 and bronze MDX4-4210, there was no statistically significant difference between incorporation methods based on solubility (p > 0.05). CONCLUSION: Based on sorption and solubility, for the A-2186 silicone, the conventional, mechanical, and industrial methods of pigment incorporation were equivalent. For the MDX4-4210 silicone, its results of sorption and solubility were varied, and further studies are recommended.

Influence of Different Pigment Incorporation Methods on Color, Dimensional Stability, and Detail Reproduction of Silicones.

OBJECTIVE: To analyze the influence of three pigment incorporation methods on color change, dimensional stability, and detail reproduction of the MDX4-4210 and A-2186 silicones. MATERIALS AND METHODS: The A-2186 and MDX4-4210 silicones were used for preparation of samples, with the incorporation of bronze, black and pink pigments, usingconventional, mechanical, and industrial incorporation methods. Samples were submitted to the initial readings of color (n = 10; 22-mm diameter × 2-mm thickness), detail reproduction, and dimensional stability (n = 10; 30-mm diameter × 3-mm thickness). Readings were also taken at the end of 252, 504 and 1,008 hours of aging cycles. RESULTS: Quantitative data were evaluated by ANOVA and Tukey test, with a level of significance of 5%. The mechanical and industrial methods caused smaller color changes of all samples compared with the conventional method (p < 0.05). In most cases, the mechanical and industrial methods caused less samples' contraction than the conventional method after aging (p < 0.05). The color change values increased progressively in each aging period for all samples (p < 0.05). The contraction values increased progressively in each aging period for all samples (p < 0.05). In the qualitative analysis of detail reproduction, all samples presented full reproduction of the three grooves, with accurate angles, initially and after the aging periods. CONCLUSIONS: The industrial and mechanical methods showed the best results for color and dimensional stability. Despite the statistical differences, all pigment incorporation methods generated acceptable dimensional and color changes of the MDX4-4210 and A-2186 silicones, regardless of the pigment and aging. In addition, the detail reproduction was satisfactory after aging periods in all cases of this study, showing the excellent quality of the A-2186 and MDX4-4210 silicones.

Influence of length, diameter and position of the implant in its fracture incidence: A Systematic Review.

Background. Implant fractures can cause difficult problems for patients and dentists. This systematic review aimed to determine the influence of some implant parameters on the occurrence of their fracture and to determine the incidence of fractures reported in recent years. Methods. A search was conducted in Pubmed database, from which 12 studies published in the last 12 years were selected. Results. This review reported a 2% incidence of implant fracture. Most implants had been in function between 3 and 4 years until fracture. The studies did not provide necessary information to establish a relationship between the different parameters of implants and the incidence of fractures. Conclusion. Thus, the indication of type, diameter and length of an implant and the bone quality in the region receiving it should be studied and accurately examined for each individual case in order to avoid future failures.

Evaluation of the level of cortisol, capillary blood glucose, and blood pressure in response to anxiety of patients rehabilitated with complete dentures.

BACKGROUND: The aim was to analyze the levels of stress of edentulous patients through the state-trait anxiety inventory (STAI) and salivary flow through the visual analogue scale (VAS) xerostomia questionnaire, as well as analyze the levels of cortisol, capillary blood glucose, and blood pressure (BP) before and after the installation of complete dentures. METHODS: Fifty patients were evaluated. The STAI and VAS xerostomia questionnaire were applied before the installation of the prosthesis, on the day of its installation, and 1 month after the last recall visit. The BP measurement, as well as salivary and blood collections, were performed before the installation of the prothesis, and 1 month after the last recall visit. Data from the VAS xerostomia questionnaire and cortisol levels were submitted to ANOVA and the Tukey test (P = .05). Data from the STAI, as well as blood glucose and BP levels, were submitted to the Chi-square test (P = .05). The correlation between cortisol and blood glucose and between cortisol levels and BP was analyzed. RESULTS: There was no statistically significant association between the questions of the VAS xerostomia questionnaire, STAI-state and STAI-trait scores, or the periods analyzed. However, the cortisol level collected in the morning decreased after the installation of the prosthesis. There was a correlation between cortisol and blood glucose and BP levels. CONCLUSIONS: The installation of complete dentures was beneficial for patients since it was probably responsible for the cortisol level reduction.

Tear Strength Analysis of MDX4-4210 and A-2186 Silicones with Different Intrinsic Pigments Incorporated by Mechanical and Industrial Methods.

OBJECTIVE: The aim of this study was to evaluate the tear strength of MDX4-4210 and A-2186 silicones with different intrinsic pigments incorporated by mechanical and industrial methods, comparing nonaged and aged groups. MATERIALS AND METHODS: Twenty-four groups were created according to the American Society for Testing and Materials D-624/type C, half nonaged and half aged (n = 10): bronze mechanical MDX4-4210, bronze industrial MDX4-4210, black mechanical MDX4-4210, black industrial MDX4-4210, pink mechanical MDX4-4210, pink industrial MDX4-4210, bronze mechanical A-2186, bronze industrial A-2186, black mechanical A-2186, black industrial A-2186, pink mechanical A-2186, and pink industrial A-2186. All specimens were submitted to tear strength analysis. Data were submitted to the ANOVA and Tukey test (p < 0.05). RESULTS: An increase in the tear strength values was observed only for the bronze and black MDX4-4210, comparing nonaged and aged silicones (p < 0.05), regardless of the manufacturing method. There was a difference in all comparisons between MDX4-4210 and A-2186 silicones with the same pigment type (p < 0.05), regardless of the manufacturing method. In all cases, there was no difference in the manufacturing method comparing the MDX4-4210 or A-2186 groups with the same pigment. CONCLUSION: Accelerated aging did not influence the tear strength in all aged A-2186 silicones and in aged pink industrial and mechanical MDX4-4210 silicones. The other MDX4-4210 groups had an increase in the results after aging. In all cases compared, the A-2186 groups had higher tear strength values than the MDX4-4210 groups. Mechanical and industrial methods can be used for silicone preparation, without changing the tear strength.

Relationship Between Implant Stability Measurements Obtained by Two Different Devices: A Systematic Review.

BACKGROUND: The aim of this systematic review is to evaluate the relationship between two methods used to assess implant stability, investigating whether both provide similar implant stability assessments for the same clinical case. METHODS: A literature search was conducted on MEDLINE-PubMed and Scopus databases, without limitation of the publication period, up to November 2015. The following key words were used, with associations among them: "dental implant," "dental implants," "Osstell," "resonance frequency analysis," "implant stability quotient," "ISQ," "Periotest," "Periotest value," and "PTV." Inclusion criteria were English language, prospective, retrospective, and randomized controlled clinical trials that evaluated implant stability through use of resonance frequency analysis (RFA) and damping capacity analysis (DCA). The study should assess implant stability of only a specific region for all patients or discriminate results evaluated for each region if the analysis had been made in various regions; RFA and DCA should have been applied in the same implants and periods. Studies have been carefully selected, and data of interest were tabulated. RESULTS: Six studies met the inclusion criteria. Although there was significant numerical correlation between values obtained by both methods, data showed that less than half (46%) of cases coincided in relation to implant stability classification. CONCLUSIONS: It can be considered that there is not always a consensus and standardization in the classification of implant stability related to the values obtained by RFA and DCA devices, which could create disagreements and miscommunication among dentistry professionals.

Biocompatibilidade de pigmentos e a influência de diferentes métodos de incorporação em propriedades físicas e mecânicas de silicones para próteses bucomaxilofaciais / Biocompatibility of pigments and the influence of different incorporation methods on physical properties of silicones for bucomaxillofacial prostheses

Uma prótese ideal deve reproduzir as estruturas perdidas nos mínimos detalhes e ser imperceptível em público. Entretanto a natureza do defeito, as habilidades do protesista e os materiais de escolha limitam a beleza da prótese e, consequentemente o seu uso, já que a sua principal função é a recuperação da estética. Sendo assim, cor, forma e textura, são características primordiais que irão determinar o sucesso ou falha da prótese bucomaxilofacial, bem como a sua durabilidade. O presente estudo tem como objetivo analisar a biocompatibilidade de um novo pigmento para coloração de próteses bucomaxilofaciais, bem como a influência dos métodos de incorporação de três pigmentos na estabilidade cromática, absorção e solubilidade, estabilidade dimensional e reprodução de detalhes dos silicones A2 A-2186 e Silastic MDX4-4210. Para a confecção das amostras, foram utilizados dois silicones faciais, três tipos de pigmentos, sendo dois deles específicos para caracterização de próteses bucomaxilofaciais nas cores bronze e preto, e um novo pigmento na cor rosa médio. Para se verificar a biocompatibilidade através dos testes in vitro de citotoxicidade com ensaios de MTT, Alamar Blue e Neutral Red com cultura de células foram confeccionadas 40 amostras, dividas em 8 grupos (n=5), de acordo com o silicone e pigmentos. Já para os testes físicos, foram confeccionadas 200 amostras para cada ensaio, divididas em 20 grupos (n=10), distribuídos de acordo com o tipo de silicone, pigmento adicionado e método de incorporação utilizado (industrial, laboratorial mecânica ou convencional). As leituras dos testes de estabilidade cromática, absorção e solubilidade, reprodução de detalhes e estabilidade dimensional foram realizadas no período inicial e ao término de cada ciclo de envelhecimento de 252, 504 e 1008 horas. Os dados obtidos foram submetidos à análise estatística, utilizando-se os testes de ANOVA (p<.05) e teste de Bonferroni para a biocompatibilidade e de Tukey para os ensaios físicos. Verificou-se, por meio dos resultados que o método de incorporação, pigmento, silicone e período avaliado influenciou as propriedades estudadas. Pode-se concluir que todos os materiais utilizados são biocompatíveis, o melhor método de Incorporação de pigmentos para estabilidade cromática é o industrial e o melhor pigmento o Rosa, todos os grupos apresentaram alterações cromáticas dentro do limite clínico considerado aceitável, os valores de absorção e solubilidade foram baixos para todos os grupos, a alteração dimensional resultou em contração das amostras, todos os grupos apresentaram uma ótima reprodução de detalhes (Escore 2)(AU)

An ideal prosthesis should reproduce the structures lost to the smallest details and be imperceptible in public. However, the nature of the defect, the skills of the prosthodontist and the materials of choice limit the beauty of the prosthesis and consequently its use, since its main function is the recovery of aesthetics. Thus, color, shape and texture are prime characteristics that will determine the success or failure of the bucomaxillofacial prosthesis as well as its durability. The present study aims to analyze the influence of the incorporation of three pigments on the color stability, absorption and solubility, dimensional stability and detail reproduction of the silicones A2 A-2186 and Silastic MDX4-4210, as well as the biocompatibility of a new pigment for staining of buccomaxillofacial prostheses. For the preparation of the samples, two facial silicones, three types of pigments were used, two of them specific for the characterization of bucomaxillofacial prostheses in bronze and black, and a new pigment in the medium pink color. In order to verify biocompatibility through in vitro cytotoxicity tests MTT, Alamar Blue and Neutral Red assays with cell culture, and 40 samples were prepared, divided into 8 groups (n=5), according to the silicon and pigments. For the physical tests, 200 samples were prepared for each test, divided into 20 groups (n=10), distributed according to the type of silicone, pigment added and method of incorporation used (industrial, mechanical or conventional laboratory). The chromatic stability, absorption and solubility, detail reproduction and dimensional stability readings were performed at baseline and at the end of each aging cycle of 252, 504 and 1008 hours. The data were submitted to statistical analysis, using ANOVA (p <.05) and Bonferroni test for biocompatibility and Tukey for physical tests. It was verified, through the results that the method of incorporation, pigment, silicone and period evaluated influenced the properties studied. It can be concluded that all the materials used are biocompatible, the best method of incorporation of pigments for chromatic stability is the industrial and pink is the best pigment, all groups presented chromatic alterations within the clinical limit considered acceptable, the absorption values and solubility were low for all groups, the dimensional change resulted in contraction of the samples, all groups presented a good reproduction of details (Score 2)(AU)

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis.

The aim of this study was to assess the effect of adding nanoparticles to N1 acrylic resin intended for artificial sclera, in terms of the color stability, microhardness, and flexural strength of the resin. Three hundred samples of N1 acrylic resin were used: 100 samples for color stability and microhardness tests (each test was performed on the opposite side of each sample), and 200 samples for flexural strength testing (100 samples before and after 1,008 hours of accelerated aging). Samples for each test were separated into ten groups (n=10), ie, without nanoparticles (control group) or with nanoparticles of zinc oxide, titanium dioxide (TiO2), and barium sulfate at weight concentrations of 1%, 2%, and 2.5% (nanoparticle groups). Data were subjected to statistical analysis with nested analysis of variance and Tukey's test (P<0.05 significance level). Among the nanoparticle groups, the TiO2 groups showed better color stability at all concentrations. Microhardness values increased after artificial aging, except for the control and zinc oxide groups. After aging, the 1%-2% TiO2 groups had significantly higher microhardness values compared with the other nanoparticle groups. Before aging, there was a significant difference in flexural strength between the control and nanoparticle groups. After aging, the control and TiO2 groups, regardless of concentration, showed the lowest flexural strength values. Incorporation of nanoparticles directly influenced the acrylic resin properties, with TiO2 being the most influential nanoparticle in terms of the evaluated properties.

Prova estética e funcional: uma decisão em conjunto / Aesthetics and functional testing: a jointly decision

Uma importante fase do tratamento reabilitador, constitui a prova estética e funcional, realizada juntamente com o paciente. A sua relevância é porque nesse momento é possível ter uma prévia muito fiel do resultado final da prótese, mas que ainda permite alterações. Assim, o objetivo dessa revisão é descrever didaticamente os passos clínicos, bem como os fatores que devem ser analisados pelo cirurgião-dentista, no momento da prova estética e funcional de uma prótese total. Esta etapa clínica envolve basicamente quatro requisitos a serem analisados: mecânicos, funcionais, estéticos e fonéticos. Após a análise em conjunto de todos os requisitos, o paciente deve aprovar, preferencialmente por escrito, a finalização das próteses. Em caso de constatação de necessidade de alguma alteração, é nesse momento que deve ser realizada, seguida de nova prova estética e funcional. É necessário salientar que a opinião do paciente é sempre soberana na decisão de finalizar a prótese total

An important phase of rehabilitation treatment, is the aesthetic and functional testing, performed with the patient. Its relevance is because at this time it’s possible to have a very faithful preview of the final result of the prosthesis, but, if necessary, still allow changes. Therefore, the objective of this review is to describe didactically the clinical steps and factors that should be examined by the dentist at the moment of aesthetic and functional testing of a complete denture. This clinical stage basically involves four requirements to be analyzed: mechanical, functional, aesthetic and phonetic. After the jointly analysis with all the requirements, the patient must approve, preferably in writing, the completion of the prosthesis. In case of need for any changes, this is when it should be performed, followed by new aesthetic and functional testing. It should be noted that the patient’s opinion is always sovereign in deciding to end the denture

Effect of different solutions on color stability of acrylic resin-based dentures.

The aim of this study was to evaluate the effect of thermocycling and immersion in mouthwash or beverage solutions on the color stability of four different acrylic resin-based dentures (Onda Cryl, OC; QC20, QC; Classico, CL; and Lucitone, LU). The factors evaluated were type of acrylic resin, immersion time, and solution (mouthwash or beverage). A total of 224 denture samples were fabricated. For each type of resin, eight samples were immersed in mouthwashes (Plax-Colgate, PC; Listerine, LI; and Oral-B, OB), beverages (coffee, CP; cola, C; and wine, W), and artificial saliva (AS; control). The color change (DE) was evaluated before (baseline) and after thermocycling (T1), and after immersion in solution for 1 h (T2), 3 h (T3), 24 h (T4), 48 h (T5), and 96 h (T6). The CIE Lab system was used to determine the color changes. The thermocycling test was performed for 5000 cycles. Data were submitted to three-way repeated-measures analysis of variance and Tukey's test (p<0.05). When the samples were immersed in each mouthwash, all assessed factors, associated or not, significantly influenced the color change values, except there was no association between the mouthwash and acrylic resin. Similarly, when the samples were immersed in each beverage, all studied factors influenced the color change values. In general, regardless of the solution, LU exhibited the greatest DE values in the period from T1 to T5; and QC presented the greatest DE values at T6. Thus, thermocycling and immersion in the various solutions influenced the color stability of acrylic resins and QC showed the greatest color alteration.

Effect of beverages and mouthwashes on the hardness of polymers used in intraoral prostheses.

PURPOSE: The mechanical properties of acrylic resins used in intraoral prostheses may be altered by frequent exposure to liquids such as beverages and mouthwashes. This study aimed to evaluate the effect of thermocycling and liquid immersion on the hardness of four brands of acrylic resins commonly used in removable prostheses (Onda Cryl, QC-20, Clássico, Lucitone). MATERIALS AND METHODS: For each brand of resin, seven specimens were immersed in each of six solutions (coffee, cola, red wine, Plax-Colgate, Listerine [LI], Oral B), and seven more were placed in artificial saliva (control). The hardness was tested using a microhardness tester before and after 5000 thermocycles and after 1, 3, 24, 48, and 96 hours of immersion. The results were analyzed using three-way repeated-measures ANOVA and Tukey's test (p < 0.05). RESULTS: The hardness of the resins decreased following thermocycling and immersion in the solutions. Specimens immersed in cola and wine exhibited significant decreases in hardness after immersion for 96 hours, although the greatest significant decrease in hardness occurred in specimens immersed in LI. However, according to American Dental Association specification 12, the Knoop hardness of acrylic resins for intraoral prostheses should not be below 15. Thus, the median values of superficial hardness observed in most of the acrylic resins in this study are considered clinically acceptable. CONCLUSIONS: The microhardness of polymers used for intraoral prostheses decreases following thermocycling. Among specimens immersed in beverages, those immersed in cola or wine experienced the greatest decrease in microhardness. Immersion of acrylic resins in LI significantly decreased the microhardness in relation to the initial value. Among the resins assessed, QC-20 exhibited the lowest initial hardness.

Influência da adição de nanopartículas sobre a dureza, resistência à ruptura e deformação permanente de silicone facial submetido ao envelhecimento acelerado / Influence of nanoparticle addition on the hardness, tear strength and permanent deformation of facial silicone subjected to accelerated aging

Apesar de satisfatórias, as próteses maxilofaciais apresentam limitações quanto à estética, conforto e durabilidade. Por isso estudos com o objetivo de melhorar as propriedades desses materiais são incessantes. É comprovada a eficiência da adição de nanopartículas na proteção de silicones, evitando a degradação da sua cor, no entanto a literatura é escassa quando se refere a outras alterações das propriedades físicas causadas no silicone facial. Assim, o objetivo deste estudo é avaliar a influência da adição de nanopartículas na ruptura, deformação permanente e dureza do Silicone Facial Silastic MDX4-4210. Foram confeccionadas 560 amostras em silicone facial, sendo 280 dessas amostras para o teste de ruptura, 140 para o teste de dureza e 140 para o teste de deformação permanente. As nanopartículas adicionadas na confecção das amostras de silicone foram: óxido de zinco (ZnO); sulfato de bário (BaSO4) e dióxido de titânio (TiO2). Para cada teste (exceção do teste de ruptura, no qual a quantidade de amostras será confeccionada em duplicata), 40 amostras de silicone serão confeccionadas com adição de cada um dos tipos de nanopartículas, totalizando 120 amostras; 10 amostras de silicone com tinta a óleo, sem nanopartículas, e 10 amostras somente de silicone .Para cada tipo de nanopartícula adicionada ao silicone facial, 20 amostras foram confeccionadas na concentração de 1% e 20 na concentração de 2%. Para cada concentração de nanopartículas, metade (10 amostras) foi com adição de tinta a óleo e a outra metade sem tinta a óleo. As amostras foram submetidas aos ensaios de dureza, resistência à ruptura e deformação permanente, e 1008 horas de envelhecimento acelerado. Os dados obtidos foram submetidos à análise estatística, utilizando-se os testes de nested ANOVA e teste de Tukey. Pode-se verificar, por meio dos resultados, que a presença de nanopartículas influenciou nos valores de dureza, resistência à ruptura e deformação permanente dos grupos avaliados...

Although satisfactory, the maxillofacial prostheses present aesthetics, comfort and durability limitations. Therefore, studies with the purpose to obtain better properties of these materials are unceasing. The efficiency of adding nanoparticles to silicon protection is well proven in preventing its color degradation, however the literature is scarce when it comes to other physical property changes with infacial silicon.The aim of this study is to evaluate the influence of nanoparticles addition to hardness, rupture resistance and permanent deformation of Facial Silicone Silastic MDX4-4210. 560 samples of facial silicone were made, 280 for rupture resistance test, 140 for hardness test and 140 for permanent deformation test. Nanoparticles added in the preparation of silicone samples were zinc oxide (ZnO), barium sulfate (BaSO4) and titanium dioxide (TiO2). For each test (except the rupture test, in which the samples are duplicated), 40 samples will be made of silicon added to each type of nanoparticles, totaling 120 samples, 10 samples of silicone with oil paint without nanoparticles, and 10 samples only of silicone (control group). For each type of nanoparticle added to the facial silicone, 20 samples were prepared at a concentration of 1% and 20 at a concentration of 2%. For every concentration of nanoparticles, half (10 samples) were added oil paint and the other half without oil paint. Samples were submitted to testing hardness, rupture resistance and permanent deformation, and 1008 hours of accelerated aging. The data were subjected to statistical analysis using nested ANOVA and Tukey tests. It can be verified through the results that the presence of nanoparticles influenced the hardness, tear strength and permanent deformation of the assessed groups. We conclude that all evaluated nanoparticles influenced the hardness, tear strength and permanent...

Influência da adição de nanopartículas sobre a dureza, resistência à ruptura e deformação permanente de silicone facial submetido ao envelhecimento acelerado / Influence of nanoparticle addition on the hardness, tear strength and permanent deformation of facial silicone subjected to accelerated aging

Apesar de satisfatórias, as próteses maxilofaciais apresentam limitações quanto à estética, conforto e durabilidade. Por isso estudos com o objetivo de melhorar as propriedades desses materiais são incessantes. É comprovada a eficiência da adição de nanopartículas na proteção de silicones, evitando a degradação da sua cor, no entanto a literatura é escassa quando se refere a outras alterações das propriedades físicas causadas no silicone facial. Assim, o objetivo deste estudo é avaliar a influência da adição de nanopartículas na ruptura, deformação permanente e dureza do Silicone Facial Silastic MDX4-4210. Foram confeccionadas 560 amostras em silicone facial, sendo 280 dessas amostras para o teste de ruptura, 140 para o teste de dureza e 140 para o teste de deformação permanente. As nanopartículas adicionadas na confecção das amostras de silicone foram: óxido de zinco (ZnO); sulfato de bário (BaSO4) e dióxido de titânio (TiO2). Para cada teste (exceção do teste de ruptura, no qual a quantidade de amostras será confeccionada em duplicata), 40 amostras de silicone serão confeccionadas com adição de cada um dos tipos de nanopartículas, totalizando 120 amostras; 10 amostras de silicone com tinta a óleo, sem nanopartículas, e 10 amostras somente de silicone .Para cada tipo de nanopartícula adicionada ao silicone facial, 20 amostras foram confeccionadas na concentração de 1% e 20 na concentração de 2%. Para cada concentração de nanopartículas, metade (10 amostras) foi com adição de tinta a óleo e a outra metade sem tinta a óleo. As amostras foram submetidas aos ensaios de dureza, resistência à ruptura e deformação permanente, e 1008 horas de envelhecimento acelerado. Os dados obtidos foram submetidos à análise estatística, utilizando-se os testes de nested ANOVA e teste de Tukey. Pode-se verificar, por meio dos resultados, que a presença de nanopartículas influenciou nos valores de dureza, resistência à ruptura e deformação permanente dos grupos avaliados...

Although satisfactory, the maxillofacial prostheses present aesthetics, comfort and durability limitations. Therefore, studies with the purpose to obtain better properties of these materials are unceasing. The efficiency of adding nanoparticles to silicon protection is well proven in preventing its color degradation, however the literature is scarce when it comes to other physical property changes with infacial silicon.The aim of this study is to evaluate the influence of nanoparticles addition to hardness, rupture resistance and permanent deformation of Facial Silicone Silastic MDX4-4210. 560 samples of facial silicone were made, 280 for rupture resistance test, 140 for hardness test and 140 for permanent deformation test. Nanoparticles added in the preparation of silicone samples were zinc oxide (ZnO), barium sulfate (BaSO4) and titanium dioxide (TiO2). For each test (except the rupture test, in which the samples are duplicated), 40 samples will be made of silicon added to each type of nanoparticles, totaling 120 samples, 10 samples of silicone with oil paint without nanoparticles, and 10 samples only of silicone (control group). For each type of nanoparticle added to the facial silicone, 20 samples were prepared at a concentration of 1% and 20 at a concentration of 2%. For every concentration of nanoparticles, half (10 samples) were added oil paint and the other half without oil paint. Samples were submitted to testing hardness, rupture resistance and permanent deformation, and 1008 hours of accelerated aging. The data were subjected to statistical analysis using nested ANOVA and Tukey tests. It can be verified through the results that the presence of nanoparticles influenced the hardness, tear strength and permanent deformation of the assessed groups. We conclude that all evaluated nanoparticles influenced the hardness, tear strength and permanent...

Stress analysis in oral obturator prostheses over parallel and tilted implants: photoelastic imaging.

This study aimed to evaluate the stress distribution through the photoelastic method in implant-retained palatal obturators prostheses. Two photoelastic models with bucco-sinusal communication were fabricated, one model without implants and another with two parallel implants and one tilted in the molar region. A conventional obturator prosthesis and five implant-retained obturators dentures with different attachment systems were fabricated: OR, three individualized O-rings; BC, bar clip; BOC, implants splinted by bars associated with two O-rings positioned at the center of the bar; OD, implants splinted by bars associated with two O-rings positioned in distal cantilever; and BOD, implants splinted by bars with clips associated with two O-rings positioned in distal cantilever. Each assembly (model/attachment system/prosthesis) was positioned in a circular polariscope and a load of 100 N was applied on each implant. The results were obtained by observing the photographic record of the tensions in the photoelastic models resulting from the application of load. It can be observed that a larger amount of stress fringes on BC system. It was concluded that the attachment system has a direct influence on the stress distribution of implant-retained obturator prostheses, with the three individualized O-rings exhibiting the lowest stress values, and tilted implants presented a biomechanical behavior similar to parallel implants.

Estudo das reabsorções em próteses removíveis / Study of resorption in removable prosthesis

A reabsorção dos rebordos residuais seguida da perda dos dentes é um processo crônico, progressivo e irreversível, observado na maioria dos pacientes usuários de próteses removíveis, total ou parcial. A taxa de perda óssea observada nos primeiros seis meses após a extração dos dentes é normalmente mais intensa, desacelerando nos anos subsequentes. Apesar da etiologia multifatorial das reabsorções, é amplamente aceito que esse processo seja primariamente induzido por cargas funcionais alteradas e transmitidas aos tecidos, podendo continuar por toda a vida. Provavelmente, uma combinação de fatores anatômicos, metabólicos, psicossociais, mecânicos e alguns desconhecidos possam influenciar a velocidade e a intensidade desse processo. O propósito desse estudo foi revisar os fatores envolvidos com a reabsorção dos rebordos residuais em usuários de próteses removíveis. Concluiu-se que a perda óssea dos rebordos alveolares residuais é um processo constante, progressivo e irreversível de origem multifatorial. A influência dos fatores sistêmicos é mais intensa do que a dos fatores locais e a capacidade do clínico em prever as situações de maior risco torna-se importante e indispensável para o prognóstico e sucesso de cada caso

The residual ridge resorption after tooth loss is a chronic, progressive and irreversible process observed in most patients using dentures, partial or complete. The rate of bone loss observed in the first six months after extraction of teeth is usually more intense, decreasing in subsequent years. Despite the multifactorial etiology of resorption, is widely accepted that this process is primarily induced by altered functional loads and transmitted to tissues, which may continue throughout life. Probably, a combination of anatomical, metabolic, psychosocial and mechanical factors may influence the speed and intensity of this process. The purpose of this study was to review the factors involved in the resorption of residual ridge in users of removable dentures. It was concluded that the alveolar bone resorption is an ongoing, progressive and irreversible process, which has multifactorial origin. The influence of systemic factors is more intense than local factors, and the ability of the clinician in predicting risk situations becomes important and essential for the prognosis and success of each case

Upper lip prosthesis retained to a palatal obturator.

In cases of total or partial maxillectomies, the prosthetic rehabilitation is an effective alternative to minimize the sequelae left by surgical resection. The present study reports a clinical case of a 52-year-old patient who underwent partial maxillectomy, with upper lip involvement. The oronasal communication, resultant from surgical resection, did not allow the patient to return to her normal social life. Besides, the upper lip partial resection damaged her face's aesthetics. The proposed treatment was the confection of an upper lip prosthesis retained by a palatal obturator. The prosthesis insertion restored the patient's facial aesthetics, contributing not only to function, but also to psychosocial adaptation.