Tracking of the degradation process of chlorhexidine digluconate and ethylenediaminetetraacetic acid in the presence of hyper-pure chlorine dioxide in endodontic disinfection.

Accurate knowledge of the safety of the combined use of hyper-pure chlorine dioxide (ClO2, Solumium) with different endodontic agents is not known. The objective was to investigate the possible interactions between hyper-pure ClO2 and Chlorhexidine digluconate (CHX) as well as hyper-pure ClO2 and ethylenediaminetetraacetic acid (EDTA) in vitro. High-performance liquid chromatography (HPLC) was used to analyse the reaction between ClO2 and CHX for studying the possible increase of para-chloroaniline (PCA). Nuclear magnetic resonance (NMR) method was applied to investigate if the oxidising property of ClO2 inactivates EDTA. CHX itself may contain PCA; however, its amount did not increase after the mixing up with ClO2. While ClO2 did not oxidise PCA, on the other hand, it oxidised EDTA into numerous degradation products, but this reaction was slow. Hyper-pure ClO2 of excellent antimicrobial properties should be considered as a safe alternative endodontic disinfectant agent in combinations or as a final rinse. The lack of chemical interaction between ClO2 and CHX confirms their safe application in combination.

Effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing: an in vitro study.

AIMS: To evaluate the effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing. MATERIALS AND METHODS: A total of 256 rectangular specimens (65 * 10 * 3 mm) 128 per resin (Lucitone-199 and Acralyn-H) were fabricated. One side of each specimen was not polished and the other was either mechanically (n = 96) or chemically (n = 96) polished and immersed for 10, 30 and 60 minutes in 2% alkaline glutaraldehyde. Mechanically polished (n = 32) and chemically polished (n = 32) control specimens were immersed only in distilled water. The transverse strength (N/mm(2)) was tested for failure in a universal testing machine, at a crosshead speed of 5 mm/min. Data were statistically analyzed using 2-way ANOVA and Student t-test. RESULTS: chemical polishing resulted in significantly lower transverse strength values than mechanical polishing. Lucitone- 199 resin demonstrated the highest overall transverse strength for the materials tested. Heat-polymerized acrylic resins either mechanically or chemically polished, did not demonstrate significant changes in transverse strength during immersion in the disinfecting solution tested, regardless of time of immersion. CONCLUSION: Lucitone-199 resin demonstrated the highest overall transverse strength for the materials tested and significantly stronger than Acralyn-H with either type of polishing following immersion in 2% alkaline glutaraldehyde. CLINICAL SIGNIFICANCE: There is a concern that immersion in chemical solutions often used for cleansing and disinfection of prostheses may undermine the strength and structure of denture base resins. In this study it was observed that, the transverse strength of samples of Lucitone-199 was higher than that of the samples of Acralyn-H. The chances of fracture of the denture made of Lucitone-199 are less than that of dentures made of Acralyn-H. The chemically polished dentures may be more prone to fracture than mechanically polished dentures.

The effect of disinfecting solutions on the dimensional stability of dental alginate impression materials.

OBJECTIVES: Dimensional changes occur in set dental alginate impression materials when immersed in disinfecting solutions. In this contribution the dimensional changes of two alginates in two disinfecting solutions, and for two specimen thicknesses, have been studied. The results were analyzed theoretically. METHODS: The dimensional changes of two commercial alginates (Blueprint Cremix and Hydrogum), have been measured, in distilled water and two disinfecting solutions (Perform ID/sodium hypochlorite), using a traveling microscope, at 5 min intervals over a period of 1h. Samples of simple geometry have been studied, namely rectangular strips with thicknesses of 1.5 and 3mm, respectively. RESULTS: In all cases, both alginates continuously shrank with time, in the three immersion liquids, over the hour of measurement, indicating transfer of water from the alginate into the external water or disinfecting solution. The t(1/2) shrinkage plots were generally linear, but with an intercept on the t(1/2) axis, indicating the possibility of an initial expansion at very short times. In most cases, the ratios of slopes for both thicknesses were 1.33-1.54, in contrast to the theoretical value of 2. Perform ID however gave anomalous results for the 1.5mm thick samples. At 10 min their shrinkage was 1.34-1.72%, compared with -0.42% to 0.67% in the other two media. SIGNIFICANCE: The effects of thickness observed were not in accord with simple Fickian theory because of the various ions diffusing into and out of the alginate. Moreover, the water content of the alginate decreased consequent on the cross-linking process.

Efecto del uso previo de soluciones desinfectantes sobre la superficie dentinaria haciendo uso de sistemas adhesivos autoacondicionadores: fuerza traccional / Effect of prior use of disinfectant solutions on the surface dentin adhesive systems using car air conditioners: tensile strength

Con el paso de los años, los sistemas adhesivos han ido evolucionando para así poder simplificar los procedimientos clínicos, es así como contamos con sistemas autograbadores-autoadhesivos que permiten reducir el tiempo operatorio. Sin embargo, sabemos que para el éxito de la restauración es necesaria la correcta eliminación del tejido cariado, por lo que se sugiere hacer uso de desinfectantes cavitarios tales como: EDTA, clorhexidina, hipoclorito de sodio; con la finalidad de reducir la carga bacteriana presente que puede poner en riesgo el tiempo de vida de la restauración. Si bien la acción de estos desinfectantes suena alentadora, su uso es muy discutido ya que no se sabe el efecto que pueda tener sobre la adhesión dental (dentinaria). El objetivo del trabajo fue realizar una revisión bibliográfica sobre el efecto del uso previo de soluciones desinfectantes sobre la superficie dentinaria haciendo uso de sistemas adhesivos autoacondicionadores. Aunque estudios realizados demuestran que la fuerza de adhesión puede incrementarse con el uso de soluciones desinfectantes, prevenir futuras afecciones pulpares así como la caries recidivante y otros que ésta no se ve afectada; existen aun investigaciones en donde los resultados no son favorables por lo que su aplicación sigue en discusión.

Tooth discoloration of immature permanent incisor associated with triple antibiotic therapy: a case report.

INTRODUCTION: A triple antibiotic mixture of ciprofloxacin, metronidazole, and minocycline was used as an intracanal medicament in an attempt to disinfect the root canal system for revascularization of a tooth with a necrotic pulp. However, discoloration developed after applying the triple antibiotic mixture. METHODS: Six weeks after a triple antibiotic paste had been applied to the root canal of tooth #8 of a 7-year-old girl, the tooth showed a dark discoloration. An in vitro experiment with human extracted teeth was performed to determine which of the 3 antibiotics caused the tooth discoloration. Another experiment was then carried out to examine whether a currently used dentin bonding agent would prevent or reduce such discoloration. The degree of discoloration was assessed by using a colorimeter. RESULTS: Among the components of the triple antibiotic paste, only minocycline caused the tooth discoloration. Moreover, the dentin bonding agent reduced the intensity of the discoloration but did not prevent it. CONCLUSIONS: The possible esthetic problems with the tooth color should be considered when using minocycline as a canal medication.

Comparison of physical and mechanical properties of microwave-polymerized acrylic resin after disinfection in sodium hypochlorite solutions.

This study evaluated the color stability, surface roughness and flexural strength of a microwave-polymerized acrylic resin after immersion in sodium hypochlorite (NaOCl), simulating 20 min of disinfection daily during 180 days. Forty disk-shaped (15 x 4 mm) and 40 rectangular (65 x 10 x 3 mm) specimens were prepared with a microwave-polymerized acrylic resin (Onda-Cryl). Specimens were immersed in either 0.5% NaOCl, 1% NaOCl, Clorox/Calgon and distilled water (control). Color measurements were determined by a portable colorimeter. Three parallel lines, separated by 1.0 mm, were registered on each specimen before and after immersion procedures to analyze the surface roughness. The flexural strength was measured using a 3-point bending test in a universal testing machine with a 50 kgf load cell and a crosshead speed of 1 mm/min. Data were analyzed statistically by ANOVA and Tukey's test (alpha=0.05). There was no statistically significant differences (p>0.05) among the solutions for color, surface roughness and flexural strength. It may be concluded that immersion in NaOCl solutions simulating short-term daily use during 180 days did not influence the color stability, surface roughness and flexural strength of a microwave-polymerized acrylic resin.

Comparison of physical and mechanical properties of microwave-polymerized acrylic resin after disinfection in sodium hypochlorite solutions

This study evaluated the color stability, surface roughness and flexural strength of a microwave-polymerized acrylic resin after immersion in sodium hypochlorite (NaOCl), simulating 20 min of disinfection daily during 180 days. Forty disk-shaped (15 x 4 mm) and 40 rectangular (65 x 10 x 3 mm) specimens were prepared with a microwave-polymerized acrylic resin (Onda-Cryl). Specimens were immersed in either 0.5 percent NaOCl, 1 percent NaOCl, Clorox/Calgon and distilled water (control). Color measurements were determined by a portable colorimeter. Three parallel lines, separated by 1.0 mm, were registered on each specimen before and after immersion procedures to analyze the surface roughness. The flexural strength was measured using a 3-point bending test in a universal testing machine with a 50 kgf load cell and a crosshead speed of 1 mm/min. Data were analyzed statistically by ANOVA and Tukey's test (?=0.05). There was no statistically significant differences (p>0.05) among the solutions for color, surface roughness and flexural strength. It may be concluded that immersion in NaOCl solutions simulating short-term daily use during 180 days did not influence the color stability, surface roughness and flexural strength of a microwave-polymerized acrylic resin.

Este estudo avaliou a estabilidade de cor, rugosidade superficial e resistência à flexão de resina acrílica polimerizada por microondas após desinfecção em hipoclorito de sódio, simulando 20 min de desinfecção diária durante 180 dias. Quarenta espécimes circulares (15 x 4 mm) e 40 retangulares (65 x 10 x 3 mm) foram preparados em resina acrílica polimerizada por microondas (Onda-Cryl). As amostras foram imersas em hipoclorito de sódio a 0,5 por cento, hipoclorito de sódio a 1 por cento, Clorox/Calgon e água destilada (controle). Medidas de cor foram determinadas por um espectrocolorímetro portátil. Três linhas paralelas, separadas por 1,0 mm, foram registradas em cada amostra antes e depois dos procedimentos de imersão para analisar a rugosidade superficial. A resistência à flexão foi medida utilizando um teste de flexão por 3 pontos em uma máquina universal de ensaios com uma célula de carga de 50 Kgf e uma velocidade de 1 mm/min. Os dados foram analisados estatisticamente por ANOVA e teste de Tukey (?=0,05). Não houve diferença estatisticamente significante (p>0,05) entre as soluções para cor, rugosidade superficial e resistência à flexão. Pode-se concluir que a imersão em soluções de hipoclorito de sódio, simulando um uso diário de curta duração durante 180 dias, não influenciou a estabilidade de cor, rugosidade superficial e resistência à flexão de resina acrílica polimerizada por microondas.

Evaluation of a standard shade guide for color change after disinfection.

OBJECTIVE: To determine if surface disinfectants cause a change in the shade perception of a standard Classic Vitapan shade guide. METHOD AND MATERIALS: Consistency in shade selection for dental restorations involves many factors, and one of the most important is the shade tabs used in the selection process. Ten shade tabs each of shades B2, D2, C1, and A3.5 were selected from the Classic Vitapan shade guide (Vident). All tabs were measured with the EasyShade shade device (Vident) at baseline. Three tabs of each shade were set aside as controls. The other 7 tabs of each shade were treated with the surface disinfectant Cavicide (Metrex Research) for 480 cycles to simulate a year's usage. After each 480 cycles, all the tabs were again measured with the EasyShade. This process was repeated to simulate 2 and 3 years of use. RESULTS: The data were analyzed to calculate the delta E 2000 for any change. A statistically significant increase was observed in the value (L*) and chroma (C*) after 2 and 3 years of simulated treatments. These changes were not perceptible to the clinician. CONCLUSIONS: The authors suggest that 1 standard shade guide be set aside to compare against those in clinical use to determine when they should be replaced.

The effect of a range of disinfectants on the dimensional accuracy and stability of some impression materials.

Disinfection of dental impressions should be considered as a routine procedure in dental surgeries and dental laboratories. Disinfectants can have deleterious effects on some properties of impression materials. The aim of this study was to evaluate the dimensional accuracy and dimensional stability of a model dental stone, reproduced from five commonly used impression materials (Aquasil soft putty/Aquasil Ultra LV; Aquasil Monophase; Aquasil Ultra Heavy; Impregum F and Provil putty/Provil Light CD wash) retained by their adhesives in acrylic resin trays and exposed to three disinfectant solutions (Perform ID; Haz-Tabs and MD 520). Two hundred models were used to investigate the effect of the three disinfectants on the dimensional accuracy of the five impression materials. Five impressions were taken for each impression material for each disinfection treatment group. Measurements were carried out using a High Precision Reflex Microscope. All materials demonstrated a percentage change in dimensions when subjected to no disinfection when compared to the brass master die and all materials demonstrated a percentage change in dimension when subjected to the different disinfection procedures. The results of this study have demonstrated that for all of the materials investigated, the changes in dimensional stability were small in the order of microns. These changes may however be of clinical significance for procedures requiring a high degree of accuracy, for example fixed prosthodontics. The materials respond differently depending on the disinfectant used and it may therefore be appropriate that manufacturers recommend the use of particular disinfectants for their products in order to ensure optimum dimensional accuracy and stability.

Effect of a dental unit waterline additive on resin bond strengths.

The literature indicates that the addition of an antimicrobial mouthrinse to self-contained water systems in dental units will control biofilm and effluent contamination; however, reports have varied concerning the possible effects of such agents on adhesive dentistry bond strengths. This study evaluated shear bond strengths and the potential effects of a mouthrinse containing essential oils on cut tooth surfaces by grinding flat the buccal surface of extracted human teeth. Seven groups consisting of five teeth each were etched with 37% H3PO4 solution and rinsed with water or different dilutions of the mouthrinse. Each tooth was blotted dry before a film of adhesive resin was applied to the surface and photocured. A cylinder of composite was placed on the surface and photocured. Shear bond strength testing was performed using a universal test machine. The cut tooth surfaces were ground (using water or the test mouthrinse mixtures as coolant) and evaluated by scanning electron microscopy.

Glutaraldehyde-induced and formaldehyde-induced allergic contact dermatitis among dental hygienists and assistants.

BACKGROUND: Research has found that among health care workers, dental personnel are especially likely to have reactions to glutaraldehyde and formaldehyde. METHODS: The authors conducted patch test evaluations with a voluntary cohort of randomly recruited, healthy dental hygienists, or DHs, and dental assistants, or DAs, and nondental professionals to determine the incidence of glutaraldehyde-induced and formaldehyde-induced allergic contact dermatitis, or ACD; the potential for coreactivity between glutaraldehyde and formaldehyde; and the correlation between training methods in safe handling of sterilizing solutions and the sensitivity to glutaraldehyde and formaldehyde among DHs and DAs. RESULTS: The researchers enrolled 101 DHs and DAs and 51 nondental professionals in the study. All except one DH/DA subject were female. The dental subjects' mean age was 34.3 +/- standard deviation of 10.7 years; the nondental subjects', 33.8 +/- 11.0 years. DHs and DAs had worked in their profession for a mean of 11.0 +/- 9.3 years. Among the dental professionals, 80 (79.2 percent) had had a known exposure to cold sterilizing solutions, while the remainder were unable to provide a known history of exposure. Eleven (10.9 percent) dental professionals had clear reactions to glutaraldehyde, four (4.0 percent) were questionably allergic to glutaraldehyde, and two (2 percent) were definitively allergic to formaldehyde. One (2 percent) control subject had a reaction to glutaraldehyde, and one other (2 percent) had a reaction to formaldehyde. CONCLUSIONS AND CLINICAL: IMPLICATIONS: The authors found a statistically significant disparity in the rates of glutaraldehyde sensitivity among healthy DHs and DAs versus healthy control subjects (10.9 percent versus 2 percent reactively; P = .02). They found no evidence of cross-reactivity between glutaraldehyde and formaldehyde. The preponderance of reactions among the DHs and DAs suggests that their present safety practices are largely ineffective in protecting against sensitization to glutaraldehyde in sterilizing solutions.

Chlorination byproducts and nitrate in drinking water and risk for congenital cardiac defects.

Drinking water disinfection byproducts have been associated with an increased risk for congenital defects including cardiac defects. Using Swedish health registers linked to information on municipal drinking water composition, individual data on drinking water characteristics were obtained for 58,669 women. Among the infants born, 753 had a cardiac defect. The risk for a cardiac defect was determined for ground water versus surface water, for different chlorination procedures, and for trihalomethane and nitrate concentrations. Ground water was associated with an increased risk for cardiac defect when crude rates were analyzed but after suitable adjustments this excess rate was found to be determined by chlorination procedures including chlorine dioxide. Chlorine dioxide appears itself as an independent risk factor for cardiac defects (adjusted odds ratio 1.61 (95%CI 1.00-2.59)). The risk for cardiac defects increased with increasing trihalomethane concentrations (P=0.0005). There was an indicated but statistically nonsignificant excess risk associated with nitrate concentration. The individual risk for congenital cardiac defect caused by chlorine dioxide and trihalomethanes is small but as a large population is exposed to public drinking water, the attributable risk for cardiac defects may not be negligible.

Are high-dose toxic exposures always associated with reactive airways dysfunction syndrome (RADS)?

Bottling plant workers were evaluated for respiratory symptoms following an accidental exposure to a chlorine dioxide aerosol. Six exposed employees underwent medical and occupational histories, skin testing to common allergens, spirometry before and after use of bronchodilators, and methacholine challenge. The reported exposure to chlorine dioxide ranged from 30 min to 12 hr. Physical examinations were all normal. Four workers had positive prick skin tests to common aeroallergens. None of the workers demonstrated significant changes in forced expiratory volume in 1 sec following use of bronchodilators, and none experienced methacholine hyperresponsiveness. These cases suggest that the occurrence of reactive airways dysfunction syndrome is unpredictable and may not always occur in heavily exposed individuals.

[Formaldehyde in dental materials]. / Formaldehyde in tandheelkundige materialen.

The use of formaldehyde in dentistry has been discussed for years. This because of the possible systemic effects of its use. This paper addresses the possible systemic effects of the use of formaldehyde and the question in which dental products formaldehyde is a component. The indications for the use of formaldehyde as its alternatives are listed. The conclusion is that for nearly all dental indications for the use of formaldehyde good alternatives are available.

The effect of cavity disinfectants on microleakage in dentin bonding systems.

The purpose of this study was to determine the effect on microleakage of two disinfectants, one a chlorhexidine based and the other alcohol based, used as cavity washes prior to the application of one step dentin bonding systems Syntac and Prime & Bond in Class V composite restorations. Children between 10-12 years old, with noncarious second primary molars about to exfoliate, were selected for this study. Cavity preparations were treated with either Syntac or Prime & Bond, combinations of one of the two disinfectants washes with Syntac or Prime & Bond or with one of the disinfectants only and filled with Tetric composite resin. All teeth were extracted one month later, stained and sectioned to evaluate dye penetration. As a result, focal dry disinfectant when used as a cavity wash prior to the use of Prime & Bond did not effect the ability of dentin bonding agents to prevent microleakage. Chlorhexidine solution had an adverse effect on Syntac and Prime & Bond and produced significantly higher microleakage when used with these bonding systems. The use of cavity disinfectants with composite resin restorations appears to be material specific regarding the interactions with various dentin bonding systems and the ability to seal dentin.