Evaluation of the mechanical properties of different materials for manufacturing occlusal splints

Abstract This study aimed to compare the mechanical properties of various occlusal plate materials by analyzing surface roughness, Knoop microhardness, flexural strength, and modulus of elasticity. Fifty samples were prepared and classified as SC (self-curing acrylic resin), WB (heat-cured acrylic resin), ME (acrylic resin polymerized by microwave energy), P (resin print), and M (polymethylmethacrylate polymer block for computer-aided design/computer-aided manufacturing). The data were analyzed using a one-way analysis of variance and Tukey's honestly significant difference test. Surface roughness was the same in all groups. The surface hardness of group M was statistically superior. The samples from groups P and M had higher flexural strength than other samples. The modulus of elasticity of group SC was statistically lower than that of other groups. The mechanical properties of the materials used to make the occlusal plates differed, and group M achieved the best results in all analyses. Therefore, clinicians must consider the material used to manufacture long-lasting and efficient occlusal splints.

Effect of different methods of hygiene on the color stability of extrinsically pigmented facial silicone

Evaluate the color stability of facial silicone pigmented extrinsically under the influence of the hygiene process. Methods: 160 samples were prepared and divided into 8 groups (n = 20) according to the pigmentation technique used: Group 1: Colorless silicone; Group 2: Pigmented exclusively with oil ink; Group 3: Pigmented with oil ink + opacifier; Group 4: Colorless, applying Prime; Group 5: Pigmented with oil ink covered with Prime; Group 6: Pigmented with oil ink + opacifier and covered with Prime; Group 7: Pigmented with oil ink diluted in Prime; Group 8: Pigmented with oil ink + opacifier diluted in Prime. Then the samples were distributed into two subgropus (n=10): 1: neutral soap and 2: 1% hypochlorite solution. The color readings occurred in the initial period and 60 days after the hygiene procedures. For this, it was used a spectrophotometer reflection and CIE-Lab program. The data was tabulated and submitted to analysis of variance (ANOVA) followed by Tukey test (p <0.05). Results: The groups of samples disinfected with soap showed significantly lower color change values than those presented by the samples disinfected with hypochlorite. The best results were presented by the group of samples pigmented with oil ink diluted in prime and sanitized with neutral soap (ΔE=1.21, without opacifier and ΔE=0.82, with opacifier). Conclusions: The association of oil ink diluted in prime and hygiene technique with soap promotes the lower color change of facial silicone pigmented extrinsically

Relationship between the morphology of the maxillary central incisor and horizontal and vertical measurements of the face.

Purpose: In order to assist in the selection of artificial teeth for complete dentures, this study aimed to assess the relationship between horizontal and vertical measurements of the face and the morphology of the maxillary central incisor. Materials and Methods: This was a study of 50 plaster casts and 100 teleradiographs - 50 in lateral norm and 50 in frontal norm, belonging to 50 individuals, Caucasian, with a naturally optimal occlusion, matching at least four of the six keys of Andrews. Images of the upper central incisors were obtained by scanning the plaster casts (three-dimensional) and subjectively classified by three examiners as oval, triangular or quadrangular. Facial measures (vertical and horizontal) were defined by means of teleradiographs. In order to check inter-examiner agreement on the classification of central incisor, the Kappa test was used. To verify whether data had normal distribution, the Kolmogorov-Smirnov test was used ( P > 0.2) was used. One-way analysis of variance was employed to assess the association between variables (P > 0.05). Results: When vertical measurements were compared with the three incisor shapes, there was no statistically significant difference (P > 0.05): Triangular (0.54), oval (0.63) and quadrangular (0.51). Similarly, no difference (P > 0.05) was found for facial width (139.08, 143.37, 141.65), maxillary width (76.68, 78.99, 76.91) and mandibular width (103.47, 105.50, 103.11). Conclusions: 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.

Bond strength between acrylic resin and maxillofacial silicone

The development of implant dentistry improved the possibilities of rehabilitation with maxillofacial prosthesis. However, clinically it is difficult to bond the silicone to the attachment system. OBJECTIVES: This study aimed to evaluate the effect of an adhesive system on the bond strength between acrylic resin and facial silicone. MATERIAL AND METHODS: A total of 120 samples were fabricated with auto-polymerized acrylic resin and MDX 4-4210 facial silicone. Both materials were bonded through mechanical retentions and/or application of primers (DC 1205 primer and Sofreliner primer S) and adhesive (Silastic Medical Adhesive Type A) or not (control group). Samples were divided into 12 groups according to the method used to attach the silicone to the acrylic resin. All samples were subjected to a T-peel test in a universal testing machine. Failures were classified as adhesive, cohesive or mixed. The data were evaluated by the analysis of variance (ANOVA) and the Tukey's HSD test (α=.05). RESULTS: The highest bond strength values (5.95 N/mm; 3.07 N/mm; 4.75 N/mm) were recorded for the samples that received a Sofreliner primer application. These values were significantly higher when the samples had no scratches and did not receive the application of Silastic Medical Adhesive Type A. CONCLUSIONS: The most common type of failure was adhesive. The use of Sofreliner primer increased the bond strength between the auto-polymerized acrylic resin and the Silastic MDX 4-4210 facial silicone.

Análise fotoelástica de tensões em próteses obturadoras palatinas implantorretidas, sobre implantes paralelos ou inclinados, associados a diferentes tipos de sistemas de retenção / Photoelastic analysis of stress in implant-retained maxillary obturator dentures using parallel or tilted implants associated with different attachment systems

Os defeitos maxilares podem reduzir drasticamente a eficiência mastigatória e a retenção das próteses destes pacientes. Logo, a associação dos implantes aos sistemas de retenção proporcionou uma nova alternativa de reabilitação para tais casos. Entretanto, a literatura é escassa em relação ao comportamento biomecânico dos diferentes sistemas de retenção em próteses obturadoras palatinas implantorretidas, principalmente em relação às tensões geradas ao implante e tecido ósseo de suporte. Desse modo, este estudo teve como propósito avaliar a distribuição de tensões, por meio do método fotoelástico, em próteses obturadoras palatinas implantorretidas, sobre implantes paralelos ou inclinados associados a diferentes tipos de sistemas de retenção. Foram confeccionados três modelos fotoelásticos a partir de um modelo maxilar experimental com comunicação buco-sinusal divididos em: modelo sem implante (SI), modelo com três implantes paralelos (IP) e modelo com dois implantes paralelos entre si (incisivo e canino) e outro inclinado (angulação distal 17°), na região de molar (II). Posteriormente, foi confeccionada uma prótese obturadora convencional (controle) e quatro próteses obturadoras palatinas implantorretidas para cada modelo com implante (IP e II) com respectivos sistemas de retenção: OR - com três O-rings individualizados, BC - barra-clip, BOC - implantes esplintados por meio de barras associados a dois O-rings posicionados no centro da barra e, BOD - implantes esplintados por meio de barras com clipes associados a dois O-rings posicionados distalmente em cantilever. O conjunto (modelo/sistema de retenção/prótese) foi posicionado em um polariscópio circular, e sobre o mesmo foi aplicada uma carga de 100N, na região de incisivo central, canino e primeiro molar (região com implantes) com o auxílio de uma Máquina de Ensaio Universal (EMIC-DL 3000). Os resultados foram obtidos pela observação do registro fotográfico das tensões nos modelos fotoelásticos, resultante...

Maxillary defects may drastically affect the masticatory efficiency and the retention of dentures of several patients. The use of implants associated with attachment systems brought a new alternative of oral rehabilitation in these cases. However, the biomechanical behavior of the different attachment systems used with implant-retained maxillary obturator dentures is still scarce in the literature in regards to stress generated over the implants and bone tissue. Thus, the current study used a photoelastic analysis to investigate the stress distribution in implant-retained maxillary obturator dentures over parallel or tilted implants associated with different attachment systems. A total of three photoelastic models based on an experimental maxillary model with oroantral communication were developed, and they were divided as follow: model without implants (SI), model with three parallel implants (IP) and model with two parallel implants (incisive and canine areas) and one tilted implant (distal angulation of 17 degrees) in the molar region (II). Afterwards, a conventional obturator denture (control) and four implant-retained obturator dentures for each implant model (IP and II) were fabricated. In the IP and II groups different attachment systems were used: OR – three independent O’rings, BC – bar-clip, BOC – splinted implants with bar associated with two O’rings placed in the center part of each bar, and BOD – splinted implants with bar-clip associated with two distally placed O’rings (in cantilever). The set (model/attachment system/denture) was placed in a circular polariscope, and a 100-N load was applied either in the central incisor, canine or first molar regions using an universal testing machine (EMIC DL-3000). The results were obtained based on the photographic records of the stress in the photoelastic models resulted from the applied load. In both IP and II groups the greatest stress concentration was observed for the BC attachment system, followed by…

Análise fotoelástica de tensões em próteses obturadoras palatinas implantorretidas, sobre implantes paralelos ou inclinados, associados a diferentes tipos de sistemas de retenção / Photoelastic analysis of stress in implant-retained maxillary obturator dentures using parallel or tilted implants associated with different attachment systems

Os defeitos maxilares podem reduzir drasticamente a eficiência mastigatória e a retenção das próteses destes pacientes. Logo, a associação dos implantes aos sistemas de retenção proporcionou uma nova alternativa de reabilitação para tais casos. Entretanto, a literatura é escassa em relação ao comportamento biomecânico dos diferentes sistemas de retenção em próteses obturadoras palatinas implantorretidas, principalmente em relação às tensões geradas ao implante e tecido ósseo de suporte. Desse modo, este estudo teve como propósito avaliar a distribuição de tensões, por meio do método fotoelástico, em próteses obturadoras palatinas implantorretidas, sobre implantes paralelos ou inclinados associados a diferentes tipos de sistemas de retenção. Foram confeccionados três modelos fotoelásticos a partir de um modelo maxilar experimental com comunicação buco-sinusal divididos em: modelo sem implante (SI), modelo com três implantes paralelos (IP) e modelo com dois implantes paralelos entre si (incisivo e canino) e outro inclinado (angulação distal 17°), na região de molar (II). Posteriormente, foi confeccionada uma prótese obturadora convencional (controle) e quatro próteses obturadoras palatinas implantorretidas para cada modelo com implante (IP e II) com respectivos sistemas de retenção: OR - com três O-rings individualizados, BC - barra-clip, BOC - implantes esplintados por meio de barras associados a dois O-rings posicionados no centro da barra e, BOD - implantes esplintados por meio de barras com clipes associados a dois O-rings posicionados distalmente em cantilever. O conjunto (modelo/sistema de retenção/prótese) foi posicionado em um polariscópio circular, e sobre o mesmo foi aplicada uma carga de 100N, na região de incisivo central, canino e primeiro molar (região com implantes) com o auxílio de uma Máquina de Ensaio Universal (EMIC-DL 3000). Os resultados foram obtidos pela observação do registro fotográfico das tensões nos modelos fotoelásticos, resultante...

Maxillary defects may drastically affect the masticatory efficiency and the retention of dentures of several patients. The use of implants associated with attachment systems brought a new alternative of oral rehabilitation in these cases. However, the biomechanical behavior of the different attachment systems used with implant-retained maxillary obturator dentures is still scarce in the literature in regards to stress generated over the implants and bone tissue. Thus, the current study used a photoelastic analysis to investigate the stress distribution in implant-retained maxillary obturator dentures over parallel or tilted implants associated with different attachment systems. A total of three photoelastic models based on an experimental maxillary model with oroantral communication were developed, and they were divided as follow: model without implants (SI), model with three parallel implants (IP) and model with two parallel implants (incisive and canine areas) and one tilted implant (distal angulation of 17 degrees) in the molar region (II). Afterwards, a conventional obturator denture (control) and four implant-retained obturator dentures for each implant model (IP and II) were fabricated. In the IP and II groups different attachment systems were used: OR – three independent O’rings, BC – bar-clip, BOC – splinted implants with bar associated with two O’rings placed in the center part of each bar, and BOD – splinted implants with bar-clip associated with two distally placed O’rings (in cantilever). The set (model/attachment system/denture) was placed in a circular polariscope, and a 100-N load was applied either in the central incisor, canine or first molar regions using an universal testing machine (EMIC DL-3000). The results were obtained based on the photographic records of the stress in the photoelastic models resulted from the applied load. In both IP and II groups the greatest stress concentration was observed for the BC attachment system, followed by…

Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing

Esthetics and durability of materials used to fabricate artificial eyes has been an important issue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin. OBJECTIVE: This study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing. MATERIAL AND METHODS: Specimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry. RESULTS: All specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h. CONCLUSIONS: Both polishing methods presented no significant difference between the values of color derivatives of resins.

Hardness evaluation of prosthetic silicones containing opacifiers following chemical disinfection and accelerated aging

We evaluated the effects of disinfection and aging on the hardness of silicones containing opacifiers and intended for use in facial prosthetics. A total of 90 samples were produced using a cylindrical metal mold 3 mm in height and 30 mm in diameter. The samples were fabricated from Silastic MDX 4-4210 silicone in three groups: GI contained no opacifier, GII contained barium sulfate (Ba), and GIII contained titanium dioxide (Ti). The samples were disinfected using effervescent tablets (Ef), neutral soap (Ns), or 4 percent chlorhexidine (Cl) 3 times a week for 60 days. After this period the samples underwent 1,008 hours of accelerated aging. The hardness was measured using a durometer immediately following the disinfection period and after 252, 504, and 1,008 hours of aging. The data were statistically analyzed using 3-way ANOVA and the Tukey test (p < .05). The GIII group exhibited the greatest variation in hardness regardless of elapsed time. All groups displayed greater hardness after 1,008 hours of accelerated aging independent of disinfectant type. All of the hardness values were within the clinically acceptable range.

Effect of accelerated aging on the microhardness and color stability of flexible resins for dentures

Acrylic resins have been widely used due to their acceptable esthetics and desirable characteristics such as easy handling, good thermal conductivity, low permeability to oral fluids and color stability. Flexible resins were introduced on the market as an alternative to the use of conventional acrylic resins in the construction of complete and partial removable dentures. Although these resins present advantages in terms of esthetics and comfort, studies assessing chromatic and microhardness alterations of these materials are still scarce in the related literature. The aim of this study was to evaluate the chromatic and microhardness alterations of two commercial brands of flexible resins in comparison to the conventional resin Triplex when submitted to accelerated aging. The resins were manipulated according to manufacturers' instructions and inserted into a silicone matrix to obtain 21 specimens divided into 3 groups: Triplex, Ppflex and Valplast. Triplex presented the highest microhardness value (p < 0.05) for all the aging periods, which was significantly different from that of the other resins, followed by the values of Valplast and Ppflex. Comparison between the flexible resins (Ppflex and Valplast) revealed a statistically significant difference (p < 0.05) as regards color. The flexible resin Ppflex and the conventional resin Triplex presented no statistically significant difference (p < 0.05) as regards aging. The accelerated aging significantly increased the microhardness values of the resins, with the highest values being observed for Triplex. Valplast presented the greatest chromatic alteration after accelerated aging.

Evaluation of hardness and surface roughness of two maxillofacial silicones following disinfection

The purpose of this study was to evaluate the Shore A hardness and surface roughness of two silicones for maxillofacial prosthetic treatment, under the influence of chemical disinfection and storage. Twenty-eight specimens were obtained, half of which were made of Silastic MDX 4-4210 silicone and, the other half were made of Silastic 732 RTV silicone. The specimens were divided into four groups: Silastic 732 RTV and MDX 4-4210 with disinfection 3 times a week with Efferdent tablets and the same materials without disinfection. The hardness of the materials was analyzed with a Shore A Durometer. The surface roughness was established by a digital portable roughness tester, initially and 2 months after the confection of the specimens. A variance test was applied (2-way ANOVA), followed by Tukey test (the level of significance was set at 1%). The storage time factor statistically influenced (p < 0.01) the materials' properties of hardness and roughness. MDX 4-4210 (28.59 Shore A, 0.789 Ra) presented higher values than Silastic 732 RTV (18.08 Shore A, 0.656 Ra) for both properties. Regarding the disinfection period, there was no significant difference in any of the materials tested.

Avaliação da microdureza superficial de quatro diferentes resinas acrílicas para base de dentaduras / Evaluation of superficial microhardness of four different acrylic resins for dentadure bases

O objetivo deste trabalho foi avaliar a microdureza superficial de quatro tipos de resinas acrílicas (Onda Cryl, Vipi Wave, Vipi Cril e QC-20 com polimerização convencional e com polimerização por energia de microondas) para base de dentaduras, em função do período de armazenagem, em água, de seis meses. Foram confeccionadas vinte e cinco amostras, as quais foram fixadas em discos acrílicos incolores, devidamente identificados, que foram então polidas em uma politriz e foram submetidas ao teste de microdureza superficial Knoop em um microdurômetro digital (modelo HMV-2T) e posteriormente armazenados em água destilada a 35 ± 2°C por seis meses, após o qual um segundo teste de microdureza superficial das amostras foi realizado. Os resultados obtidos foram submetidos à análise de variância e ao teste de Tukeyao nível de significância de 5%. Observou-se que o fator tempo de armazenagem promoveu um decréscimo dos valores médios de microdureza superficial Knoop para todos os grupos estudados, sendo que apenas para os grupos Vipi Cril e QC-20 polimerizado por energia de microondas esta diminuição dos valores foi estatisticamente significativa.

Influência da inclusão, polimento e período de armazenagem, sobre a rugosidade de resinas acrílicas para próteses oculares / Influence of the enclosure, polishing and period of storage, about the roughness of the acrylic resins in the making of ocular prosthetics

A proposta desse estudo foi avaliar a rugosidade de resinas acrílicas próprias para confecção de próteses oculares, submetidas a dois diferentes métodos de inclusão e polimento, antes e após 60 dias de armazenagem. Foram confeccionados 24 corpos-de-prova, obtidos a partir de discos em resina acrílica incolor confeccionados em prensa semi-automática. Osdiscos foram incluídos em muflas próprias para microondas, utilizando dois diferentes tipos de materiais para revestimento, gesso especial e silicone de condensação. Após a presa final do gesso, as muflas foram abertas, os discos retirados e a resina prensada e polimerizada em forno microondas. Após o resfriamento natural das muflas, os corpos-de-prova foram desincluídos e submetidos ao acabamento e polimento. Dos 24 corpos-de-prova obtidos, 12 receberam polimento mecânicoe restante polimento químico. Os corpos-de-prova foram submetidos ao teste de rugosidade de superfície, antes e apósum período de armazenagem de 60 dias, utilizando um rugosímetro digital portátil modelo RP100 (Tonka Sul AmericanaLtda, Brasil). Para cada corpo-de-prova foram realizadas 3 leituras que posteriormente foram transformadas em valores médios. Os resultados obtidos foram avaliados utilizando análise de variância seguido pelo teste de Tukey em nível de 5% de significância. Em todos os grupos houve um aumento na rugosidade superficial após 60 dias de armazenagem, porém estes valores só foram estatisticamente significantes para os corpos-de-prova polidos quimicamente. O grupo silicone proporcionou menores valores de rugosidade para os grupos quimicamente polidos. Independente do polimento empregado e do tempo de armazenagem, a inclusão com gesso proporcionou maiores valores de rugosidade superficial.

Odontologia e a doença de Alzheimer / Geriatric dentistry and the Alzheimer disease

A população mundial está envelhecendo,principalmente nos países em desenvolvimento como o Brasil.Com o envelhecimento populacional, o número de patologias,próprias da velhice, surgirá com maior freqüência. Dentre essas doenças podemos citar a de Alzheimer, uma demência irreversível, na qual tem sido associado à idade, à doença cérebro vascular, ao infarto do miocárdio, a defeitos imunológicos e a fatores genéticos (síndrome de Down). Sabe-se que com a progressão da demência, os pacientes apresentam dificuldade de higienização oral, principalmente porque os portadores de doença de Alzheimer ficam com as funções cognitivas e motoras diminuídas. Seus portadores são pacientes que demandam estratégias específicas para que o cirurgião dentista possa atendê-lo sem maior dificuldade.Objetivo: Fazer uma revisão de literatura sobre a relação entre a odontogeriatria e a doença de Alzheimer, enfocando as características dos pacientes com esse tipo de demência e os cuidados para com eles. Para isso, foi utilizando o indexador Medline database, no período de 1972 a 2006, com o cruzamento dos termos alzheimer disease and dentistry e o indexador BBO, no período de 1987 a 2004, com o termogeriatria. Conclusão: Os estudos, de uma forma geral,indicaram que os pacientes portadores dessa doença apresentam maiores problemas de saúde bucal em relação aos não portadores

Associação de dois sistemas de retenção em overdenture sobreimplantes / Association of two systems of retention in implants overdenture

O presente trabalho tem como objetivo, viabilizar a utilização de dois implantes osseointegrados com o sistema de retenção barra-clip e dois o’rings em cantilever distais no desenvolvimento de um caso clínico de overdenture inferior.

Efeito dos tratamentos superficiais para reparo em cerâmica: avaliação por meio da microscopia eletrônica de varredura / Effect of the superficial treatments to porcelain repair: scanning electron microscopy evaluation

As falhas em Prótese Parcial Fixa podem ocorrer de muitas maneiras, sendo a fratura da porcelana associada ao grupo de problemas mecânicos. Esta ocorrência pode ser reparada sem a necessidade de remoção da peça protética, embora a substituição da restauração seja considerada a solução ideal. Assim, diferentes tratamentos superficiais são utilizados para melhorar a força de união entre cerâmica – resina e viabilizar o reparo. Este estudo analisou a superfície cerâmica tratada com ácido fosfórico à 37% e ácido fluorídrico à 9,5% por meio da microscopia eletrônica de varredura. Quaren-ta amostras cerâmicas (VITA Zahnfabrik, Alemanha), foram confeccionadas a partir de uma matriz metálica circular, com dimensões de 10mmx3mm. As amostras foram divididas nos seguintes grupos, I) controle – sem tratamento; II) tratamento com ácido fluorídrico à 9,5% por 1 minuto; III) tratamento com ácido fluorídrico à 9,5% por 2 minutos; IV) tratamento com ácido fosfórico à 37% por 1 minuto; V) tratamento com ácido fosfórico à 37% por 2 minutos. Após os respectivos tratamentos, as amostras foram metalizadas (20Kv, 15mA, 2 minutos), no aparelho Denton Vaccum Desk II, sendo em seguida, analisadas no MEV (JEOL – JSM 5410). As superfícies tratadas com ácido fosfórico à 37% por 1 ou 2 minutos não apresentaram alterações morfológicas significativa, enquanto a superfície cerâmica tratada com ácido fluorídrico à 9,5% por 1 minuto já apresentou alteração morfológica significativa, sendo este achado mais evidente após 2 minutos de aplicação. Clinicamente este trabalho sugere um reparo mais eficiente quando a superfície cerâmica é tratada com ácido fluorídrico.