Surface detail reproduction and dimensional accuracy of molds: influence of disinfectant solutions and elastomeric impression materials / Reprodução de detalhes da superfície e estabilidadedimensional de moldes: influência das soluçõesdesinfetantes e elastômeros

This study compared the surface detail reproduction anddimensional accuracy of molds after disinfection using 2% sodium hypochlorite, 2% chlorhexidine digluconate or 0.2% peracetic acid to those of molds that were not disinfected, forfour elastomeric impression materials: polysulfide (Light Bodied Permlastic), polyether (Impregum Soft), polydimethylsiloxane(Oranwash L) and polyvinylsiloxane (Aquasil Ultra LV). Themolds were prepared on a matrix by applying pressure, using aperforated metal tray. The molds were removed followingpolymerization and either disinfected (by soaking in one of thesolutions for 15 minutes) or not disinfected. The samples werethus divided into 16 groups (n=5). Surface detail reproductionand dimensional accuracy were evaluated using opticalmicroscopy to assess the 20 ­µm line over its entire 25 mm length. The dimensional accuracy results (%) were subjectedto analysis of variance (ANOVA) and the means were comparedby Tukey’s test (α=5%). The 20 ­µm line was completelyreproduced by all elastomeric impression materials, regardlessof disinfection procedure. There was no significant difference between the control group and molds disinfected with peraceticacid for the elastomeric materials Impregum Soft (polyether)and Aquasil Ultra LV (polyvinylsiloxane). The high­leveldisinfectant peracetic acid would be the choice material for disinfection.

Este estudo comparou a reprodução de detalhes da superfície e estabilidade dimensional de moldes obtidos após desinfecção utilizando hipoclorito de sódio 2%, digluconato de clorexidina 2%, ou ácido peracético 0,2% a moldes que não foram desinfetados com quatro elastômeros: polissulfeto (Light Bodied Permlastic), polieter (Impregum Soft), silicona reação porcondensação (Oranwash L) e silicona reação por adição (Aquasil Ultra LV). Os moldes foram preparados sobre matriz conten dolinhas de 20, 50 e 75 µm realizado sob pressão com moldeirade metal perfurada. Os moldes foram removidos após a polimerização e desinfetados (utilizando uma das soluções porimersão, armazenados em frascos fechados durante 15 minutos)ou não desinfetados. Assim, as amostras foram divididas em 16grupos (n=5). A reprodução detalhes da superfície e a precisão dimensional foram avaliadas usando microscopia óptica na linha 20 µm com 25 mm de comprimento, de acordo com a norma ISO 4823. Os resultados de precisão dimensional (%) foram submetidos à análise de variância (A NOVA) e as médias comparadas pelo teste de Tukey com 5% de nível de significância. A linha de 20 µm foi completamente reproduzida por todos os elastômeros, independentemente do processo de desinfecção. Não houve diferença estatisticamente significativa entre o grupo controle e moldes desinfetados com acido peracético para os elastômeros Impregum Soft (polieter) e Aquasil Ultra LV (siliconareação por adição). O desinfetante de alto nível ácido peracético seria o material de escolha para a desinfecção.

Assessment of the amount of residual sodium hypochlorite after chemical disinfection of heat-polymerized resins / Evaluación de la cantidad de hipoclorito de sodio residual después de la desinfección química de resina termo-polimerizadas

Aim To evaluate the release of sodium hypochlorite from three different commercial brands of heat-polymerized acrylic resin immersed in water and submitted to mechanical or chemical polishing after disinfection with hypochlorite at different concentrations. Material and methods Fifty-four disk-shaped specimens (n = 18) were made for each resin (Lucitone 550, QC-20, and Classico) and assigned to two groups according to the type of polishing. Specimens were divided in three sub-groups in relation to sodium hypochlorite concentration (1%, 2.5%, and 5.25%), and the groups were immersed for 10-min periods in each sodium hypochlorite concentration. The electrochemical method used for detecting the release of sodium hypochlorite in each specimen was the cyclic voltammetry. Results In the specimens of Clássico resin polished mechanically and immersed in 5.25% sodium hypochlorite, as well as Lucitone and QC-20 resins immersed in 2.5%, the amounts of disinfectant solution released in the four 15-min water exchanges were higher than the four 60-min exchanges. Conclusion There were differences in hypochlorite release from the three commercial brands of denture-base acrylic resins subjected to mechanical polishing. However, no hypochlorite release from the same resins was observed when they were subjected to chemical polishing.

Objetivo Evaluar la liberación de hipoclorito de sodio de 3 marcas comerciales diferentes de resinas termo-polimerizadas sumergidas en agua, y sometidas a pulido mecánico o químico después de la desinfección con hipoclorito a diferentes concentraciones. Material y métodos Cincuenta y cuatro especímenes en forma de disco (n = 18) fueron confeccionados para cada resina (Lucitone 550, QC-20 y Clássico) y asignados a 2 grupos de acuerdo con el tipo de pulido. Las muestras se dividieron en 3 subgrupos en relación con la concentración de hipoclorito de sodio (1, 2,5 y 5,25%), y los grupos se sumergieron durante períodos de 10 min en cada concentración de hipoclorito de sodio. El método electroquímico usado para la detección de la liberación de hipoclorito de sodio en cada espécimen fue a través de voltametría cíclica. Resultados En las muestras pulidas mecánicamente de resina Clássico inmerso en hipoclorito de sodio al 5,25%, así como en las resinas Lucitone y QC-20 inmersas a 2,5%, la cantidad de solución desinfectante liberada en los 4 intercambios de agua de 15 min fue superior a los 4 de 60 min. Conclusión Hubo diferencias en la liberación de hipoclorito de las 3 marcas comerciales de resinas acrílicas sometidas a pulido mecánico. Sin embargo, no se observó liberación de hipoclorito en las mismas resinas cuando se sometieron a pulido químico.

Evaluation of toothbrush disinfection via different methods

The aim of this study was to compare the efficacy of using a dishwasher or different chemical agents, including 0.12% chlorhexidine gluconate, 2% sodium hypochlorite (NaOCl), a mouthrinse containing essential oils and alcohol, and 50% white vinegar, for toothbrush disinfection. Sixty volunteers were divided into five experimental groups and one control group (n = 10). Participants brushed their teeth using toothbrushes with standard bristles, and they disinfected the toothbrushes according to instructed methods. Bacterial contamination of the toothbrushes was compared between the experimental groups and the control group. Data were analyzed by Kruskal–Wallis and Duncan's multiple range tests, with 95% confidence intervals for multiple comparisons. Bacterial contamination of toothbrushes from individuals in the experimental groups differed from those in the control group (p < 0.05). The most effective method for elimination of all tested bacterial species was 50% white vinegar, followed in order by 2% NaOCl, mouthrinse containing essential oils and alcohol, 0.12% chlorhexidine gluconate, dishwasher use, and tap water (control). The results of this study show that the most effective method for disinfecting toothbrushes was submersion in 50% white vinegar, which is cost-effective, easy to access, and appropriate for household use.

Effect of denture cleansers on metal ion release and surface roughness of denture base materials

Chemical disinfectants are usually associated with mechanical methods to remove stains and reduce biofilm formation. This study evaluated the effect of disinfectants on release of metal ions and surface roughness of commercially pure titanium, metal alloys, and heat-polymerized acrylic resin, simulating 180 immersion trials. Disk-shaped specimens were fabricated with commercially pure titanium (Tritan), nickel-chromium-molybdenum-titanium (Vi-Star), nickel-chromium (Fit Cast-SB Plus), and nickel-chromium-beryllium (Fit Cast-V) alloys. Each cast disk was invested in the flasks, incorporating the metal disk to the heat-polymerized acrylic resin. The specimens (n=5) were immersed in these solutions: sodium hypochlorite 0.05%, Periogard, Cepacol, Corega Tabs, Medical Interporous, and Polident. Deionized water was used as a control. The quantitative analysis of metal ion release was performed using inductively coupled plasma mass spectrometry (ELAN DRC II). A surface analyzer (Surftest SJ-201P) was used to measure the surface roughness (µm). Data were recorded before and after the immersions and evaluated by two-way ANOVA and Tukey's test (α=0.05). The nickel release proved most significant with the Vi-Star and Fit Cast-V alloys after immersion in Medical Interporous. There was a significant difference in surface roughness of the resin (p=0.011) after immersion. Cepacol caused significantly higher resin roughness. The immersion products had no influence on metal roughness (p=0.388). It could be concluded that the tested alloys can be considered safe for removable denture fabrication, but disinfectant solutions as Cepacol and Medical Interporous tablet for daily denture immersion should be used with caution because it caused greater resin surface roughness and greater ion release, respectively.

Desinfetantes químicos são normalmente associados a métodos mecânicos para remover manchas e reduzir a formação do biofilme. Este estudo avaliou o efeito de desinfetantes na liberação de íons metálicos e na rugosidade superficial do titânio comercialmente puro, ligas metálicas e resina acrílica termopolimerizável, simulando 180 ensaios de imersões. Espécimes em formato de discos foram confeccionados com titânio comercialmente puro (Tritan), liga de níquel-cromo-molibdênio-titânio (Vi-Star), liga de níquel-cromo (Fit Cast-SB Plus) e liga de níquel-cromo-berílio (Fit Cast-V). Os espécimes (n=5) foram imersos nestas soluções: hipoclorito de sódio a 0,05%, Periogard, Cepacol, Corega Tabs, Medical Interporous e Polident. Como controle, foi utilizada a água deionizada. A análise quantitativa de liberação de íons metálicos foi realizada por meio de espectrometria de massa com plasma indutivamente acoplado (ELAN DRC II). O rugosímetro (Surftest SJ-201P) foi utilizado para medir a rugosidade superficial (µm). Os dados foram registrados antes e depois das imersões e avaliados por ANOVA com dois fatores e teste de Tukey (α=0,05). A liberação de níquel provou ser mais expressiva nas ligas Vi-Star e Fit Cast-V após a imersão em Medical Interporous. Houve diferença significante na rugosidade superficial da resina (p=0,011) após a imersão. O Cepacol causou maior rugosidade superficial de forma significativa. Os produtos de imersão não influenciaram nos resultados da rugosidade do metal (p=0,388). Pode-se concluir que as ligas metálicas testadas podem ser consideradas seguras para a fabricação de próteses removíveis, mas as soluções desinfetantes como o Cepacol e a pastilha Medical Interporous para a imersão diária da prótese devem ser utilizados com cautela, pois causaram maior rugosidade superficial da resina e maior liberação de íons, respectivamente.

Surface detail reproduction and dimensional accuracy of stone models: influence of disinfectant solutions and alginate impression materials

This study compared the surface detail reproduction and dimensional accuracy of stone models obtained from molds disinfected with 2% sodium hypochlorite, 2% chlorhexidine digluconate or 0.2% peracetic acid to models produced using molds which were not disinfected, with 3 alginate materials (Cavex ColorChange, Hydrogum 5 and Jeltrate Plus). The molds were prepared over matrix containing 20-, 50-, and 75-µm lines, performed under pressure with perforated metal tray. The molds were removed following gelation and either disinfected (using one of the solutions by spraying followed by storage in closed jars for 15 min) or not disinfected. The samples were divided into 12 groups (n=5). Molds were filled with dental gypsum Durone IV and 1 h after the start of the stone mixing the models were separated from the tray. Surface detail reproduction and dimensional accuracy were evaluated using optical microscopy on the 50-µm line with 25 mm in length, in accordance with the ISO 1563 standard. The dimensional accuracy results (%) were subjected to ANOVA. The 50 µm-line was completely reproduced by all alginate impression materials regardless of the disinfection procedure. There was no statistically significant difference in the mean values of dimensional accuracy in combinations between disinfectant procedure and alginate impression material (p=0.2130) or for independent factors. The disinfectant solutions and alginate materials used in this study are no factors of choice regarding the surface detail reproduction and dimensional accuracy of stone models.

Este estudo comparou a reprodução de detalhes da superfície e alteração dimensional de modelos de gesso obtidos a partir de moldes desinfetados com hipoclorito de sódio 2%, digluconato de clorexidina 2%, ou ácido peracético 0,2% a modelos confeccionados utilizando moldes que não foram desinfetados com três alginatos (Cavex ColorChange, Hydrogum 5, Jeltrate Plus). Os moldes foram preparados sobre matriz contendo linhas de 20, 50 e 75 µm realizado sob pressão com moldeira de metal perfurada. Os moldes foram removidos após a geleificação e desinfetados (utilizando uma das soluções por pulverização, armazenados em frascos fechados durante 15 min) ou não desinfetados. Assim, as amostras foram divididas em 12 grupos (n=5). Os moldes foram preenchidos com gesso dental Durone IV e uma hora após a manipulação do gesso os modelos foram separados da moldeira. A reprodução de detalhes da superfície e a precisão dimensional foram avaliadas usando microscopia óptica na linha 50 µm com 25 mm de comprimento, de acordo com a norma ISO 1563. Os resultados de precisão dimensional (%) foram submetidos à ANOVA. A linha de 50 µm foi completamente reproduzida por todos os alginatos, independentemente do processo de desinfecção. Não houve diferença estatisticamente significativa nos valores médios de precisão dimensional nas combinações entre procedimento de desinfecção e alginato (p=0,2130), ou para fatores independentes. Soluções desinfetantes e alginatos utilizados neste estudo não são fatores de escolha em relação à reprodução de detalhes da superfície e alteração dimensional de modelos de gesso.

Effect of repeated immersion solution cycles on the color stability of denture tooth acrylic resins

OBJECTIVE: Chemical solutions have been widely used for disinfection of dentures, but their effect on color stability of denture tooth acrylic resins after repeated procedures is still unclear. The aim of this in vitro study was to evaluate whether repeated cycles of chemical disinfectants affected the color stability of two denture tooth acrylic resins. MATERIAL AND METHODS: Sixty disc-shaped specimens (40 mm x 3 mm) were fabricated from two different brands (Artiplus and Trilux) of denture tooth acrylic resin. The specimens from each brand (n=30) were randomly divided into 6 groups (n=5) and immersed in the following solutions: distilled water (control group) and 5 disinfecting solutions (1 percent sodium hypochlorite, 2 percent sodium hypochlorite, 5.25 percent sodium hypochlorite, 2 percent glutaraldehyde, and 4 percent chlorhexidine gluconate). Tooth color measurements were made by spectrophotometry. Before disinfection, the initial color of each tooth was recorded. Further color measurements were determined after subjecting the specimens to 7, 21, 30, 45, 60, and 90 immersion cycles in each tested solution. Color differences (ΔE*) were determined using the CIE L*a*b* color system. Data were analyzed using two-way repeated measures analysis of variance (ANOVA) followed by Tukey tests. The significance level was set at 5 percent. RESULTS: There were statistically significant differences in ΔE* among the 5 disinfectants and water during the 90 cycles of immersion for both denture tooth acrylic resins. Distilled water promoted the greatest color change in both denture tooth acrylic resins, nevertheless none of tested disinfectants promoted ΔE* values higher than 1.0 on these acrylic materials during the 90 cycles of disinfection. CONCLUSIONS: Repeated immersion cycles in disinfecting solutions alter ΔE* values, however these values do not compromise the color of the tested denture tooth acrylic resins because they are imperceptible to the human eye.

The effect of disinfectant agents on dimensional stability and surface roughness of a tissue conditioner material.

Purpose: The aim of this study was to determine the effect of disinfectant procedures on the dimensional stability and surface quality of a tissue conditioner used as a functional impression material. Materials and Methods: A tissue conditioner (Visco-gel) used as a functional impression material was disinfected by immersion in 5.25% sodium hypochlorite or 2% glutaraldehyde solutions for 10 or 20 minutes, respectively. The control group consisted of specimens (n=10) that were not treated by disinfectants. For testing the dimensional stability, impressions of an aluminum edentulous arch with three reference points were made. After 24 hours of storage in distilled water, the specimens were treated by one of the disinfection procedures. Impressions were poured and, subsequently, 50 stone casts were measured with a Nikon profile projector. For surface roughness evaluation, disks that contained Visco-gel were pressed against glass slides. The disks were then stored in distilled water for 24 hours. After disinfection, 50 disk-shaped dental stone casts were prepared. Surface roughness values were determined using a profilometer. For each test, data were subjected to two-way analysis of variance (ANOVA) followed by Tukey's test (α = 0.05). Results: The results of the dimensional stability test showed that immersion of Visco-gel impressions in 5.25% sodium hypochlorite solution or 2% glutaraldehyde solution did not significantly change the anteroposterior (AP) and cross-arch (CA) distances of the resultant stone casts when compared to the control group (P>0.05). The surface quality of dental stone casts formed by Visco-gel did not change significantly when impressions were immersed in the disinfectant solutions for either 10 or 20 minutes, or when stored in distilled water (P>0.05). Conclusion: The results showed that the disinfectant solutions used in this study did not have a significant effect on the surface quality and dimensional accuracy of Visco-gel as a functional impression material.

Glutaraldehyde release from heat-polymerized acrylic resins after disinfection and chemical and mechanical polishing

This study evaluated the release of glutaraldehyde from heat-polymerized acrylic resins subjected to disinfection followed by chemical and mechanical polishing. Ninety disc-shaped specimens (15 x 4 mm), 30 per resin (Lucitone 550, QC-20 and Classico), were made and assigned to 2 groups according to the type of polishing. One side of each specimen was not polished and the other was either mechanically (n=45) or chemically (n=45) polished, and immersed in water at 50°C for 1 h to allow the release of intrinsic substances and then kept in distilled water for 7 days. The specimens were disinfected by immersion in 2% glutaraldehyde for 10 min. After this period, 3 specimens from each group were immersed in water for 15, 30, 60, 120 and 240 min. For the 15-, 30-, 60-min immersions, 4 water exchanges were done at the end of period. High performance liquid chromatography (HPLC) was used to detect and quantify the glutaraldehyde released after each period. Data were analyzed statistically by two-way ANOVA and multiple comparisons were done by Tukey’s and Scheffé’s tests (α=0.05). No glutaraldehyde release was observed from the specimens with chemical polishing at any of the immersion periods, while the mechanically polished specimens released glutaraldehyde. In the groups with water exchanges, Lucitone released more disinfectant in the 15-min period (0.040 μg/mL), Classico in the 30-min (0.021 μg/mL) and 60-min (0.018 μg/mL) periods, and QC-20 the same amount (-1.760 μg/mL) in all periods. In the groups without water exchanges, Lucitone released the highest amount of disinfectant (-1.370 μg/mL), differing significantly from QC-20 (0022 g/mL) and Classico (0019 g/mL), which were similar. The findings of this showed that chemically polished specimens from the 3 resin brands did not release glutaraldehyde after different periods of immersion, while glutaraldehyde release was observed from the mechanically polished specimens, especially from those made of Lucitone resin.

Este estudo determinou a liberação de glutaraldeído de resinas acrílicas termopolimerizáveis submetidas a polimento químico e mecânico e desinfetadas. Noventa corpos-de-prova circulares (15 x 4 mm), 30 de cada tipo de resina (Lucitone, QC-20 e Clássico), foram confeccionados e divididos em 2 grupos referentes ao tipo de polimento. Um dos lados de cada corpo-de-prova não foi polido e o outro foi polido mecanicamente (n=45) ou quimicamente (n=45), e imersos em água aquecida a 50°C por 1 h para liberação de substâncias intrínsecas e mantidos em água destilada por 7 dias. A seguir era realizada a desinfecção por imersão em solução de glutaraldeído a 2% por 10 min. Decorrido este período, três corpos-de-prova de cada grupo eram imersos em água por 15, 30, 60, 120 e 240 min. Nos períodos de 15, 30 e 60 min foram realizadas até 4 trocas de água após cada período. As amostras eram analisadas por meio de cromatografia líquida de alta eficiência (HPLC) após cada período. Os dados foram analisados estatisticamente pela Análise de Variância e testes complementares de Tukey e Scheffé (α=0,05). Os corpos-de-prova com polimento químico, de todas as marcas comerciais de resina, não liberaram glutaraldeído em qualquer um dos períodos de imersão em água, enquanto os com polimento mecânico liberaram. Nos grupos com trocas de água, a resina Lucitone liberou maior quantidade de desinfetante nas trocas de 15 min (0,040 μg/mL), a resina Clássico nas de 30 (0,021 μg/mL) e 60 min (0,018 μg/mL) e a QC-20 liberou a mesma quantidade (-1,760 μg/mL), em todos os períodos de imersão em água. Nos grupos sem trocas de água, a resina Lucitone liberou maior quantidade de desinfetante (-1,370 μg/mL), sendo diferente estatisticamente das resinas QC-20 (0,022 μg/mL) e Clássico (0,019 μg/mL), que são similares. Pelos resultados conclui-se que corpos-de-prova polidos quimicamente, das três marcas comerciais de resina, não liberaram glutaraldeído após os diferentes períodos de imersão. Contudo, nos corpos-de-prova polidos mecanicamente houve liberação do desinfetante, com Lucitone liberando maior quantidade em relação às demais resinas estudadas.

An evaluation of the mechanical properties of Type III and Type IV gypsum mixed with two disinfectant solutions.

Background and Objectives: This in-vitro study was conducted to evaluate the strength and properties of Type III and Type IV gypsum mixed with disinfectant solutions. Materials and Methods: Type III and Type IV gypsum were used for the study. Three different mixing solutions namely waterqueous solutions of 0.525% sodium hypochlorite and 2% glutaraldehyde were used. Gypsum materials were subjected to further modification by adding a mixture of 1.0% gum arabic and 0.132% calcium hydroxide before mixing with the disinfectant solutions, at two different liquid/powder (L/P) ratios for each. Both, the unmodified and the modified gypsum were tested for compressive and tensile strength after one hour and one week from the start of the mix. The crystalline configuration of the fracture fragments of the unmodified and modified set gypsum were studied under the scanning electron microscope. Results: The disinfectant solutions reduced the strength of both Type III and Type IV gypsum. Water showed higher-strength, which was followed by 0.525% sodium hypochlorite and 2% glutaraldehyde. The modified Type III and Type IV gypsum with reduced L/P ratio also showed strength values less than that of the control groups. Interpretation and Conclusion: Chemical disinfectants reduced the strength of gypsum when used as water substitutes. Gum Arabic and calcium hydroxide additives permitted lower L/P ratio, however, there was still excess water retained in the set gypsum that lowered the strength values of Type III and Type IV gypsum. Hence, further reduction of L/P ratio may increase the properties of the modified Type III and Type IV gypsum.

Antimicrobial efficacy of chemical disinfectants on contaminated full metal crowns

Prosthetic restorations that have been tried in the patient's mouth are potential sources of infection. In order to avoid cross-infection, protocols for infection control should be established in dental office and laboratory. This study evaluated the antimicrobial efficacy of disinfectants on full metal crowns contaminated with microorganisms. Full crowns cast in a Ni-Cr alloy were assigned to one control group (n=6) and 5 experimental groups (n=18). The crowns were placed in flat-bottom glass balloons and were autoclaved. A microbial suspension of each type of strain - S. aureus, P. aeruginosa, S. mutans, E. faecalis and C. albicans- was aseptically added to each experimental group, the crowns being allowed for contamination during 30 min. The contaminated specimens were placed into recipients with the chemical disinfectants (1 percent and 2 percent sodium hypochlorite and 2 percent glutaraldehyde) for 5, 10 and 15 min. Thereafter, the crowns were placed into tubes containing different broths and incubated at 35ºC. The control specimens were contaminated, immersed in distilled water for 20 min and cultured in Thioglycollate broth at 35ºC. Microbial growth assay was performed by qualitative visual examination after 48 h, 7 and 12 days. Microbial growth was noticed only in the control group. In the experimental groups, turbidity of the broths was not observed, regardless of the strains and immersion intervals, thus indicating absence of microbial growth. In conclusion, all chemical disinfectants were effective in preventing microbial growth onto full metal crowns.

Restaurações protéticas provadas na cavidade bucal dos pacientes são fontes potenciais de infecção. Para evitar infecção cruzada, protocolos de controle de infecção devem ser estabelecidos no consultório e laboratório odontológicos. Este estudo avaliou a eficácia antimicrobiana de desinfetantes químicos em coroas metálicas contaminadas com microorganismos. Coroas totais fundidas com liga de Ni-Cr foram divididas em grupo controle (n=6) e 5 grupos experimentais (n=18). As coroas foram colocadas em balões de vidro e esterilizadas em autoclave. A suspensão microbiana de cada tipo de cepa (S. aureus, P. aeruginosa, S. mutans, E. faecalis e C. albicans) foi assepticamente adicionada a cada grupo experimental, e as coroas foram deixadas contaminar por 30 min. Os corpos-de-prova contaminados foram colocados em recipientes com os desinfetantes químicos (hipoclorito de sódio 1 por cento e 2 por cento e glutaraldeído) por 5, 10 e 15 min. A seguir, as coroas foram colocadas em tubos contendo diferentes meios de cultura e incubadas a 35ºC. Os corpos-de-prova do grupo controle foram contaminados, imersos em água destilada por 20 min e a seguir colocados em tubos de ensaio com meio de cultura Thioglycollate e incubados a 35ºC. A análise do crescimento microbiano foi realizada pelo exame visual qualitativo após 48 h, 7 e 12 dias. Houve crescimento microbiano apenas no grupo controle. No grupo experimental não foi observada turvação dos meios de cultura, independentemente das cepas e períodos de imersão. Conclui-se que todos desinfetantes químicos foram eficazes para prevenir o crescimento microbiano.

study on the effect of chemical disinfectants on acrylic resin cured by two different techniques

New requirements for infection control in dentistry is of an utmost need in which dentures must be handled before delivery to patients. This study was undertaken in attempt to study the changes in some physical and mechanical properties of heat cured acrylic resin cured by two different techniques, the conventional water bath and microwave energy after disinfection by immersion for 7 days in 0.5% chlorhexidine, 2% gluteraldehyde, 0.55 sodium hypochloride and 70% ethanol. The results showed that only ethanol is not suitable to be used for disinfection of heat cured acrylic resin cured by either method