Academic literature on the topic 'Elastomers in dentistry'

Maxillofacial silicone elastomers are used to replace and reconstruct missing facial parts for patients with trauma or a certain disease. Although commonly favorable silicone elastomers are not ideal in properties, many studies have been carried out to improve their mechanical properties and to come out with ideal maxillofacial prosthetic materials, so as to render patients with the best maxillofacial prostheses. The aim of the current study is to evaluate the effect of addition of different concentrations of polyester powder on hardness, tear strength, surface roughness, and tensile strength of maxillofacial A-2186 RTV silicone elastomers. Polyester powder was added to the silicone elastomer in the concentrations of 1%, 3% and 5% by using an electronic digital balance, compared with the control group of 0% polyester filler. The shore A hardness test was done according to ASTM D 2240 standards. The tear test was done according to ASTM D624 type C standards. The tensile test was done according to ISO specification number 37:2011. The surface roughness test was performed according to ISO 7619-1 2010 specifications. The data collected were then analyzed using one-way analysis of variance (ANOVA) and post hoc and Fisher’s LSD tests. All three groups showed a highly significant increase in tear strength, tensile strength, hardness, and roughness, compared to the control group. Reinforcement of A-2186 Platinum RTV Silicone Elastomer with 5% polyester significantly improved the mechanical properties tested in this study.

The aim of this study was to determine quantitatively and qualitatively the inorganic particle fraction of commercially available dental elastomers. The inorganic volumetric fraction of two addition silicones (Reprosil Putty/Fluid and Flexitime Easy Putty/Fluid), three condensation silicones (Clonage Putty/Fluid, Optosil Confort/Xantopren VL and Silon APS Putty/Fluid), one polyether (Impregum Soft Light Body) and one polysulfide (Permlastic Light Body) was accessed by weighing a previously determined mass of each material in water before and after burning samples at 600ºC, during 3 h. Unsettled material samples were soaked in acetone and chloroform for removal of tthe organic portion. The remaining filler particles were sputter-coated with gold evaluation of their morphology and size, under scanning electron microscopy (SEM). Flexitime Easy Putty was the material with the highest results for volumetric particle fraction, while Impregum Soft had the lowest values. Silon 2 APS Fluid presented the lowest mean filler size values, while Clonage Putty had the highest values. SEM micrographs of the inorganic particles showed several morphologies - lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. The results of this study revealed differences in particle characteristics among the elastometic materials that could lead to different results when testing mechanical properties.

Molding in a fixed prosthesis is one of the most important stages in rehabilitative treatment, as it is there that attempts are made to reproduce dental preparations and adjoining regions by using appropriate materials and techniques. Among the fixed prosthesis molding materials available on the market, the elastomers stand out, which are polymers where the prey occurs through the increase of the chain and the establishment of cross-links. The objective of the study is to present a clinical case and perform a literature review on the use of condensation silicone and addition to molds in Fixed Prosthesis. In this literature review, a survey of PubMed, Scielo and Lilacs data was performed, using the descriptors: Denture, Partial, Fixed; Dental Impression Materials and Elastomers. It is possible to conclude that in the field of Dentistry, the elastomers, among them the condensation-cured and addition-cured silicones, both provide high precision models and are the most used materials in works with fixed partial dentures. Therefore, it is up to the professional to know the properties and adapt to the best group of chosen materials.

ABSTRACT Background Autoclave sterilization and microwave sterilization has been suggested as the effective methods for the disinfection of elastomeric impressions, but subjecting elastomeric impressions to extreme temperature may have adverse effects on critical properties of the elastomers. Aim To evaluate the effect of chemical disinfection as well as autoclave and microwave sterilization on the surface roughness of elastomeric impression materials. Materials and methods The surface roughness of five commercially available polyvinyl siloxane impression materials (Coltene President, Affinis Perfect impression, Aquasil, 3M ESPE Express and GC Exafast) were evaluated after subjecting them to chemical disinfection, autoclaving and microwave sterilization using a Talysurf Intra 50 instrument. Twenty specimens from each material were fabricated and divided into four equal groups, three experimental and one control (n = 25). The differences in the mean surface roughness between the treatment groups were recorded and statistically analyzed. Results No statistically significant increase in the surface roughness was observed when the specimens were subjected to chemical disinfection and autoclave sterilization, increase in roughness and discoloration was observed in all the materials when specimens were subjected to microwave sterilization. Conclusion Chemical disinfection did not have a significant effect but, since it is less effective, autoclave sterilization can be considered effective and autoclaving did not show any specimen discoloration as in microwave sterilization. Microwave sterilization may be considered when impressions are used to make diagnostic casts. A significant increase in surface roughness may produce rougher casts, resulting in rougher tissue surfaces for denture and cast restorations. Clinical significance Autoclave sterilization of vinyl polysiloxane elastomeric impressions for 5 minutes at 134°C at 20 psi may be considered an effective method over chemical disinfection and microwave sterilization, because chemical disinfection does not eliminate all disease-causing microorganisms and microwave sterilization leads to a rougher impression surface. How to cite this article Al Kheraif AA. Surface Roughness of Polyvinyl Siloxane Impression Materials Following Chemical Disinfection, Autoclave and Microwave Sterilization. J Contemp Dent Pract 2013;14(3):483-487.

ABSTRACT Aim The aim of this study was to evaluate the influence of immersion period in two disinfectant solutions on dimensional change of four elastomeric impression materials. Materials and methods Four representative materials of each class of elastomers: Xantopren (polydimethylsiloxane—PDS), Express (polyvinyl siloxane—PVS); Permlastic (polysulfide— PS) and Soft Impregum (polyether—EP) were mixed according to manufacturers’ instructions and then inserted into a metal matrix prepared according to the specification of ISO 4823. The molds were removed from the matrix after 7 minutes and immersed in disinfectant solutions (sodium hypochlorite 0.5 and 2% glutaraldehyde) for 5, 10, 20, 30 and 60 minutes (n = 7), except the control group, which was not immersed. Once removed from solutions, the test samples were washed in water for 15 seconds, dried and measured three times, using a comparative optical microscope, with accuracy of 0.0005 mm. The analysis of variance with three criteria and Tukey's test with significance level of 5% showed that differences in linear dimensions of the materials analyzed were not statistically significant (p > 0.05) after soaking in sodium hypochlorite 0.5 and 2% glutaraldehyde, for the tested periods of time. Clinical significance Combinations of molding material and disinfecting solution can be used in the dental clinic for infection control, without changing the dimensional molds, for immersion periods not longer than 20 minutes. How to cite this article Carvalhal CIO, de Mello JAN, Sobrinho LC, Correr AB, Sinhoreti MAC. Dimensional Change of Elastomeric Materials after Immersion in Disinfectant Solutions for Different Times. J Contemp Dent Pract 2011;12(4): 252-258.

Orientadores: Mario Alexandre Coelho Sinhoreti, Carlos Jose Soares
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Baseado no entendimento incompleto de como o conteúdo de partículas de carga influencia nas propriedades mecânicas dos materiais de moldagem este estudo avaliou quantitativa e qualitativamente o conteúdo de partículas de carga inorgânicas presente em cinco marcas comerciais de alginatos (Jeltrate; Jeltrate Plus, Jeltrate Chromatic Ortho, Hydrogum e Ezact Krom) e nove marcas comerciais de siliconas de adição e/ou condensação nas consistências massa e/ou fluida (Clonage, Elite HD+ Light Body, Express Light Body, Flexitime, Optosil P Confort/Xantopren VL Plus, Oranwash L, Reprosil A+, Silon 2 APS e Virtual Extra Light Body). Foram realizados testes para determinar recuperação elástica e deformação sob compressão dos alginatos e dos elastômeros e estabelecer, dessa forma, uma correlação entre os resultados para partículas de carga e os testes mecânicos. O conteúdo volumétrico das partículas de carga foi determinado pesando-se as amostras submersas em água antes e após a queima das mesmas durante 3h a 450°C (alginatos) e a 600°C (siliconas). Quantidades determinadas de materiais não polimerizados foram lavadas em acetona e clorofórmio e recobertas com ouro para avaliação da morfologia e tamanho das partículas em M.E.V. A composição foi determinada por EDX. A recuperação elástica e a deformação sob compressão foram determinadas de acordo as especificações ? 1563 (alginatos) e 4823 (elastômeros) da ISO. O alginatos Jeltrate e Jeltrate Plus apresentaram os maiores valores médios para quantidade volumétrica de partículas de carga (%) enquanto o material Hydrogum apresentou os menores valores. A silicone de adição Flexitime Easy Putty apresentou os maiores valores de quantidade volumétrica de partículas, enquanto que a silicone de condensação Xantopren VL Plus apresentou os menores. As partículas de carga dos alginatos apresentaram-se, de forma geral, como objetos esféricos e com perfurações. O material Hydrogum apresentou forma de bastões cilíndricos e perfurados. As siliconas apresentaram morfologias variadas ¿ partículas trituradas, esféricas, esferóides, bastões cilíndricos perfurados e bastões misturados a partículas usinadas. O alginato Ezact Krom apresentou os maiores valores médios de tamanho de partícula, enquanto que o alginato Hydrogum as menores. A silicone de condensação Clonage massa apresentou os maiores valores médios de tamanho de partícula, enquanto a silicone de adição Elite HD os menores. A análise da composição das partículas apresentou o silício como o elemento em maior quantidade. Com relação aos resultados de recuperação elástica, o alginato Ezact Krom e as siliconas Reprosil A+ massa e Flexitime fluida apresentaram os maiores valores de recuperação elástica, enquanto o alginato Jeltrate Plus e as siliconas Optosil P Confort e Clonage fluida apresentaram os menores. Os resultados de deformação sob compressão foram maiores para o alginato Jeltrate Plus e para as siliconas Silon 2 APS massa e fluida. Os menores resultados foram apresentados pelo alginato Ezact Krom e as siliconas Reprosil A+ massa e Xantopren VL Plus. Todos os materiais estão em conformidade com a norma ISO ?1563, mas nem todos estão em relação à norma ?4823
Abstract: Based on the incomplete understanding on how filler features influence the properties of elastomeric impression materials, the purpose of this study was to determine the inorganic filler fraction and size of five commercially available alginates (Jeltrate; Jeltrate Plus, Jeltrate Chromatic Ortho, Hydrogum e Ezact Krom) and nine addition/condensation silicones using the putty/light consistence (Clonage, Elite HD+ Light Body, Express Light Body, Flexitime, Optosil P Confort/Xantopren VL Plus, Oranwash L, Reprosil A+, Silon 2 APS e Virtual Extra Light Body). A SEM/EDX analysis was done to qualitatively characterize the materials. Soon afterwards elastic recovery and strain in compression of the alginates and some the silicones was carried. The inorganic particles volumetric fractions were accessed by weighing a previously determined mass of each material in water before and after burning samples for 3 hours at 450ºC (alginates) and 600ºC (silicones). Unsettled materials were soaked in acetone and chloroform and sputter-coated with gold for SEM evaluation of fillers¿ morphology and size. The filler composition was determined by EDX. Elastic recovery and strain in compression tests were conducted according to ISO specification number 1563 and 4823. Jeltrate and Jeltrate Plus presented the highest mean values of percentage content of inorganic particles in volume, while Jeltrate Chromatic Ortho presented the lowest values. Flexitime Easy Putty was the silicone with the highest mean value, while Xantopren VL Plus had the lowest value. The alginate fillers presented a circular appearance with helical form and various perforations. Hydrogum fillers looked like cylindrical, perforated sticks. SEM pictures of the silicone inorganic particles showed numerous morphologies ¿ lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. Ezact Krom was the alginate with the highest values for diameter size, while Hydrogum had the lowest. Clonage Putty showed the highest values, while Elite HD+ Light Body presented the lowest values. The component in higher concentration in the materials is silicon. The alginate Ezact Krom, and the addition cure silicones Reprosil A+ putty and Flexitime Correct Flow had the highest mean values of elastic recovery, while the alginate Jeltrate Plus and the condensation cured silicones Optosil P Confort and Clonage Putty presented the lowest values. Strain in compression test showed the alginate Jeltrate Plus and the condensation cured silicones Silon 2APS Putty and Fluid as the materials with the highest values. The alginate Ezact Krom and the silicones Reprosil A+ Putty and Xantopren VL Plus had lowest values. All materials are in conformity with the requirements of ISO specification number 1563, but not all materials are in conformity with the requirements of ISO specification number 4823
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários

Objective: The purpose of this in vitro study was to determine if there is a difference in force decay between three sliding retraction methods under a standardized force delivery system (200 gm at 25 mm stretch) at 2, 4, 6, and 8 weeks. Background: In order to achieve proper esthetics, occlusion and stability, orthodontic treatment may require extractions. Elastomeric chains, Nickel Titanium (NiTi) coils, and active ligatures are commonly used to close these extraction spaces. Methods: Twenty samples of each retraction method (elastomeric chains, NiTi Coils and active ligatures) were evaluated under standardized conditions (200 gm at 25 mm). The force of each retraction method was measured at 0, 2, 4, 6, and 8 weeks on a customized force gauge test stand (Shimpo FGV-1XY force gauge; Shimpo Instruments, Itasca, IL). Ten control samples were evaluated at 0 weeks and left un-stretched until the final measurement at 8 weeks. All samples were stored in a bath of Fusayama/Meyer artificial saliva (Pickering Laboratories, Mountain View, California) at 37°C in order to simulate the oral cavity. Results: At 2 weeks, the NiTi coils maintained their force while both the elastomeric chains and active ligatures experienced a statistically significant decrease in force over time. At 4, 6, and 8 weeks, the force of the elastomeric chains and active ligatures continued to decay and demonstrated a statistically significant decrease in force as compared to the NiTi coils and each other. At 8 weeks, the NiTi coils, elastomeric chains and active ligatures maintained 94.0%, 66.8% and 50.9%, respectively. This signifies a hierarchy of force decay with NiTi coils maintaining the largest amount of force, followed by the elastomeric chains and then the active ligatures. Conclusion: There is a significant difference in the amount of force decay of the three retraction methods over time under a standard initial force delivery of 200 gm over a 25 mm stretch. NiTi coils provide the light and constant force desired for efficient and biologically compatible tooth movement. The elastomeric chains maintained a larger amount of force than expected and have proven to achieve comparable tooth movement to NiTi coils in clinical studies. Active ligatures do not appear to be an effective means of force delivery. A force gauge is recommended to evaluate all forces placed clinically.

The traditional occlusal indicators used in dental practice are articulation papers, Shim-stock foils, elastomeric impression materials, and occlusal wax strips. These static dental materials have been widely believed to have occlusal force descriptive capability. However, modern material studies are challenging the widespread belief that occlusal indicator materials can measure differing occlusal force levels. This chapter evaluates the force reporting limitations of these static occlusal indicators, and discusses how clinicians subjectively interpret their appearance characteristics to determine differing occlusal force levels. This chapter then compares these non-digital occlusal indicators to the T-Scan computerized occlusal analysis technology, that records and displays precise, quantifiable, relative occlusal force variances, and occlusal contact timing sequences. This digital data aids the clinician in making a more accurate occlusal analysis, and can guide the clinician in the correction of occlusal contact force and timing abnormalities, thereby eliminating the subjectivity that is inherent with traditional occlusal indicator use. This chapter further details the diagnostic occlusal capabilities of the T-Scan's digital force and timing data, by presenting two separate studies that compared measured closure and excursive occlusal contact force and timing parameters in orthodontic and non-orthodontic young adults. A commentary is included regarding the clinical pitfalls of using maximally invasive, subjective interpretation to choose occlusal contacts for treatment instead of employing minimally invasive, computer-guided occlusal contact selection. This last section clearly illustrates to the reader that both patients and dentists will markedly benefit from the implementation of occlusal measurement technology.