Efecto de la exposición a bebidas carbonatadas en la dureza superficial de resinas acrílicas / Effect of Exposure to Carbonated Beverages on the Surface Hardness of Acrylic Resins

ABSTRACT: The purpose of this study was to evaluate and compare the effect of carbonated beverage on the surface microhardness of two acrylic materials used to fabricate temporary restorations. The study was experimental in vitro. Forty blocks of acrylic resins used in provisional restorations were made, 20 from Alike® (GC AMERICA INC., Lot 1712161) and 20 from Acryptemp® (Zhermack S.P.A., Lot 302334). After that, the blocks were immersed in distilled water for 24 hours. After this time, the initial surface microhardness was measured. Then the 20 samples of the experimental group were immersed in a carbonated drink (coca cola - soda) for 12 minutes per day, for 5 days. Finally, the final surface microhardness was measured using the Vickers microdurometer. Measures of central tendency and dispersion were used, and the Student's t test and ANOVA were performed. A mean surface microhardness of 8.8 and 7.2HV was found for the PMMA resin group (Initial and final respectively), and 9.5 and 8HV for the bisacrylate group. Statistically significant differences were found when comparing the beginning and end of each group and when comparing the two materials. The acrylic resin of polymethylmethacrylate (Alike® GC AMERICA INC.) Presented higher surface microhardness compared to the bis acrylic resin (Acrytemp® Zhermack S.P.A), after being exposed to a carbonated drink.

RESUMEN: El propósito de este estudio fue evaluar y comparar el efecto de la bebida carbonatada en la microdureza superficial de dos materiales acrílicos utilizados para confeccionar restauraciones provisionales. El estudio fue experimental in vitro. Se confeccionaron 40 bloques de resinas acrílicas utilizadas en provisorios, 20 de Alike® (GC AMERICA INC., Lote 1712161) y 20 de Acryptemp® (Zhermack S.P.A., Lote 302334). Posterior a ello, se sumergió los bloques en agua destilada por 24 horas. Pasado este tiempo se procedió a medir la microdureza superficial inicial. Luego las 20 muestras del grupo experimental se sumergieron en una bebida carbonatada (coca cola-gaseosa) durante 12 minutos por día, durante 5 días. Por último se midió la microdureza superficial final mediante el microdurómetro de Vickers. Se utilizaron medidas de tendencia central, dispersión y se realizaron la prueba t de Student y ANOVA. Se encontró una microdureza superficial media de 8,8 y 7,2HV para el grupo de resina PMMA (Inicial y final respectivamente), y 9,5 y 8HV para el grupo de bisacrilato. Se halló diferencias estadísticamente significativas al comparar el inicio y final de cada grupo y al comparar los dos materiales. La resina acrílica de polimetilmetacrilato (Alike® GC AMERICA INC.) presentó mayor microdureza superficial en comparación con la resina bis acrílica (Acrytemp® Zhermack S.P.A), después de ser expuestas a una bebida carbonatada.

Effect of Commercial Effervescent Vitamin Tablets on Bovine Enamel / 치위생과학회지

BACKGROUND: In this study, four types of effervescent vitamins marketed in Korea were analyzed for their acidity and vitamin content. For this purpose, bovine teeth were immersed in vitamin, and surface microhardness and appearance were measured before and after immersion to evaluate tooth demineralization and erosion.METHODS: Bovine permanent incisors with sound surface enamel were cut to 5×5 mm size, embedded in acrylic resin, and polished using a polishing machine with Sic-paper. The prepared samples were analyzed for pH, vitamin content, and surface hardness before and after immersion using a surface microhardness meter. Demineralization of surface dental enamel was observed using a scanning electron microscope.RESULTS: The average pH of the four effervescent vitamins was less than 5.5; the pH of the positive control Oronamin C was the lowest at 2.76, while that of the negative control Samdasoo was the highest at 6.86. The vitamin content was highest in Berocca and lowest in the DM company Multivitamin. On surface microhardness analysis, surface hardness values of all enamel samples were found to be decreased significantly after 1 and 10 minutes of immersion (p<0.05). After 10 minutes of immersion, there was a significant difference in the decrease in hardness between the experimental groups (p<0.05). Scanning electron microscopy observation showed that dental enamel demineralization after 10 minutes of immersion was the most severe in Oronamin C except for Samdasoo, followed by DM company Multivitamin and VitaHEIM. Immersion in BeroNew and Berocca resulted in similar effects.CONCLUSION: There is a risk of tooth erosion due to decreased tooth surface microhardness when using the four types of effervescent vitamins and vitamin carbonated beverages with pH below 5.5. Therefore, high pH vitamin supplements are recommended to prevent tooth erosion.

Evaluación de la microdureza superficial de resinascompuestas: revisión de la literatura / Evaluation of the surface microhardness of composite resins: literature review

En la actualidad, ha aumentado considerablemente el uso de resinas compuestas, llegando a convertirse en el principal material restaurador utilizado por los odontólogos, tanto para el sector anterior como el posterior. Dentro de sus propiedades, encontramos la dureza, la cual forma parte muy importante para determinar su durabilidad en boca. Esta propiedad está determinada por la cantidad de relleno que presente la resina, por ende, a mayor cantidad de relleno, mayor será su dureza y menores cambios dimensionales. A pesar de todas las mejoras en tecnología y propiedades de las resinas compuestas, aún no se encuentra un material que posea características ideales que lo hagan indestructible al paso de los años. El objetivo de este artículo es revisar las principales características de las resinas compuestas, especialmente la microdureza superficial. La dureza es una condición de la superficie de un material determinado, no representa ninguna propiedad de la materia y está relacionada con las propiedades elásticas y plásticas de cada material. Existen en la actualidad muchos sistemas para medir la dureza, por ejemplo, sistema Brinell, Rockwell, Vickers y Knoop

At present, the use of composite resins has increased considerably, becoming the main restorative material used by dentists, both for the anterior and posterior sectors. Among its properties, we find the hardness, which is a very important part to determine its durability in the mouth. This property is determined by the amount of filler that the resin presents, therefore, the greater the amount of filler, the greater its hardness and smaller dimensional changes. Despite all the improvements in technology and properties of composite resins, there is still no material that has ideal characteristics that make it indestructible over the years. The objective of this article is to review the main characteristics of composite resins, especially surface microhardness. Hardness is a condition of the surface of a given material, it does not represent any property of the material and is related to the elastic and plastic properties of each material. There are currently many systems to measure hardness, for example, Brinell, Rockwell, Vickers and Knoop systems.

Comparative evaluation of application of different fluoride varnishes on artificial early enamel lesion: An in vitro study

Introduction: In an attempt to manage noncavitated carious lesions noninvasively through remineralization, a range of novel fluoride varnishes with additional remineralizing agents have been made available for clinical application. Aim and Objectives: The aim of this study was to compare and evaluate the remineralization potential of three commercially available varnishes on artificial enamel lesions. Materials and Methods: This in vitro study involves eighty intact enamel specimens prepared from premolars extracted for orthodontic purposes. After specimen preparation, the eighty samples were divided randomly into two groups (n = 40) for measurement of baseline surface Vickers microhardness and baseline calcium/phosphorus ratio (% weight) through EDAX testing. Thereafter, the specimens were subjected to demineralization for 96 h to induce initial enamel lesions and the measurements were repeated. Following demineralization, each of the two groups was divided randomly into four subgroups (n = 10) from which one was used as the control group and the others three were allotted to each of the three test varnishes. After varnish application, all the specimens were subjected to a pH cycling regimen that included alternative demineralization (3 h) and remineralization (21 h) daily, for 5 consecutive days. The Vickers microhardness and EDAX measurements were then repeated. Results: One-way ANOVA and post hoc Tukey's tests were conducted for multiple group comparison. All the three commercially available varnishes were capable of remineralizing initial enamel lesions that were induced artificially. No difference was noted in the remineralizing efficacy of the varnishes despite their different compositions. MI Varnish™ (casein phosphopeptide-amorphous calcium phosphate fluoride varnish) showed slightly better recovery in surface microhardness as compared to the other two varnishes. Conclusion: All the varnishes used in this in vitro study are capable of reversing early enamel lesions.

Carbohydrate-electrolyte drinks exhibit risks for human enamel surface loss

OBJECTIVES: The aim of this investigation was to give insights into the impact of carbohydrate-electrolyte drinks on the likely capacity of enamel surface dissolution and the influence of human saliva exposure as a biological protective factor. MATERIALS AND METHODS: The pH, titratable acidity (TA) to pH 7.0, and buffer capacity (β) of common beverages ingested by patients under physical activity were analyzed. Then, we randomly distributed 50 specimens of human enamel into 5 groups. Processed and natural coconut water served as controls for testing three carbohydrate-electrolyte drinks. In all specimens, we measured surface microhardness (Knoop hardness numbers) and enamel loss (profilometry, µm) for baseline and after simulated intake cycling exposure model. We also prepared areas of specimens to be exposed to human saliva overnight prior to the simulated intake cycling exposure. The cycles were performed by alternated immersions in beverages and artificial saliva. ANOVA two-way and Tukey HDS tests were used. RESULTS: The range of pH, TA, and β were 2.85 - 4.81, 8.33 - 46.66 mM/L and 3.48 - 10.25 mM/L × pH, respectively. The highest capacity of enamel surface dissolution was found for commercially available sports drinks for all variables. Single time human saliva exposure failed to significantly promote protective effect for the acidic attack of beverages. CONCLUSIONS: In this study, carbohydrate-electrolyte drinks usually consumed during endurance training may have a greater capacity of dissolution of enamel surface depending on their physicochemical proprieties associated with pH and titratable acidity.

Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

OBJECTIVES: To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. MATERIALS AND METHODS: OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. RESULTS: Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). CONCLUSIONS: Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.

Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

OBJECTIVES: To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. MATERIALS AND METHODS: OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. RESULTS: Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). CONCLUSIONS: Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.

The effects of calcium sodium phosphosilicate on the enamel remineralization of primary teeth / 实用口腔医学杂志

Objective:To study the effect of calcium sodium phosphosilicate(CSP)on the enamel remineralization of primary teeth. Methods:30 extracted human healthy primary molars were collected.Each tooth was cut bucco-lingually and mesial-distally into 4 sections.The sections were assigned randomly into 4 groups(n =30).Demineralization and remineralization cyclic model was estab-lished by etching with 35% phosphate acid for 2 min and then treated by unexposure of the sample to nothing(control,group A),so-dium monofluorophosphat(MFP,group B),CSP(group C)and MFP +CSP(group D).The cyclic was repeated twice daily for 30 d. The enamel surface morphology was observed by SEM and the surface microhardness(SMH)was measured.Results:On the tenth day,squamous morphology was observed on the enamel surface of group A and that of group D appeared less demineralization.The SMH value of group D was significant higher than that of group A(P <0.05).On the thirtieth day,obvious demineralization was ob-served in group A.Group B,C and D appeared surface remineralization.The SMH value of group B,C and D was significant higher than that of group A(P <0.05).Highest SMH value was achieved in group D.Conclusion:CSP combined with fluoride is more ef-fective in the enamel remineralization of primary teeth than the single application of them.

Remineralizing efficacy of Calcarea Fluorica tablets on the artificial carious enamel lesions using scanning electron microscope and surface microhardness testing: In vivostudy.

Context: Remineralization is defined as the process whereby calcium and phosphate ions are supplied from a source external to tooth to promote ion deposition into crystal voids in demineralized enamel to produce net mineral gain. The remineralization produced by saliva is less and also a slow process, therefore remineralizing agents are required. Aims: The study was planned to evaluate the effectiveness of homeopathic Calcarea Fluorica (calc‑f) tablets as remineralizing agents on artificial carious lesions using scanning electron microscope (SEM) and surface microhardness (SMH) testing. Subjects and Methods: A total of 24 patients needing removable orthodontic treatment were included in the study. They were divided into two groups of 12 patients each. The Group I consisted of patients in whom no tablets were given while Group II consisted of patients in whom calc‑f tablets were given in a dosage of 4 tablets twice a day. Four enamel samples with the artificial carious lesions were then embedded in the removable appliance for a period of 6 weeks. After 6 weeks, the enamel samples were retrieved and evaluated by SEM and SMH. Statistical Analysis Used: One‑sample Kolmogorov–Smirnov test and Student’s t‑test were applied to analyze the difference in the Vickers microhardness number (VHN) values of remineralized enamel obtained from control and experimental group. Results: The signs of remineralization such as reduction in depth prismatic holes or decrease in porosity, variable sized uneven distribution of deposits and amorphous deposits were seen in enamel samples of both the groups. The mean SMH of remineralized enamel sample of Group I and Group II were 270.48 and 302.06, respectively, and the difference was statistically significant. Conclusions: (1) Remineralization occurred in both the groups as indicated by SEM and the increase in surface hardness values in both the groups. (2) Remineralization of enamel samples in the control group as indicated by SEM and also by increase in VHN values indicated that the saliva has a tendency of remineralizing the early carious lesions. Conclusions drawn from the study are that the calc‑f tablets can be used as safe and cost effective remineralizing agent.

Effect of red vinegar drink on the surface of sound enamel / 대한구강보건학회지

OBJECTIVES: The aim of this study was to evaluate the effect of red vinegar drink on sound enamel surface. METHODS: Commercially available red vinegar drink was used for the study. Firstly, pH values were measured in commercially available red vinegar drinks. Secondly, four groups; mineral water as the control group and red vinegar drink, red vinegar drink + mineral water (mixing ratio, 1:3), red vinegar drink + milk (mixing ratio,1:4) as the experimental group were selected. Forty specimens of bovine teeth were made and then divided into the four groups and treated with the test drinks for 1, 15, 30 and 60 minutes. The surface microhardness (vickers hardness number, VHN) was measured using the microhardness tester before and after the treatments. The surface of specimens was observed with Scanning Electron Microscopy (SEM). RESULTS: The average pH of red vinegar drinks was 2.91+/-0.02. The change values (before treatment - after treatment of surface microhardness of enamel surface) were significantly difference among groups (P<0.05). There was no significant difference between control and red vinegar drink + milk (1:4) and there was the significant difference between control group and red vinegar drink groups, and control and red vinegar drink + mineral water (1:3) groups. In SEM, damage of enamel surface was observed in Red vinegar and Red vinegar+Mineral water group. CONCLUSIONS: The results showed that the all experimental red vinegar drinks, except red vinegar drink + milk (1:4) can reduce the surface microhardness of sound enamel. Thus, it is suggested that the red vinegar drink with milk could be recommended the preventive eating method for reducing the risk of dental erosion on the red vinegar drink diet.

The influence of the die hardener on gypsum die / 대한치과보철학회지

STATEMENT OF PROBLEM: Die materials require abrasion resistance, dimensional stability with time, and high surface wettability for adequate material properties. Wear of gypsum materials is a significant problem in the fabrication of accurately fitting cast prosthetic devices. So It has been recommended that the use of die hardener before carving or burnishing ofthe wax pattern. PURPOSE: The purpose of this study was to compare the abrasion resistance and surface microhardness(Knoop) with 3 commonly used gypsum die materials(MG Crystal Rock, Super plumstone, GC FUJIROCK(R) EP) with and without the application of 2 die hardeners. MATERIAL AND METHODS: Three die materials were evaluated for abrasion resistance and surface microhardness after application of 2 die hardeners(Die hardener and Stone die & plaster hardener). Thirty specimens of each gypsum material were fabricated using an impression of resin die(Pattern resin; GC Corporation, Japan) with 1-mm high ridges, sloped 90 degrees. Gypsum materials were mixed according to manufacturer's recommendations and allowed to set 24 hours before coating. Specimens were arbitrary assigned to 1 of 3 treatment subgroups (n=10/subgroup): no treatment(control), coated with Die hardener, and coated with Stone die & plaster hardener. Abrasion resistance(measured by weight loss) was evaluated using device in 50g mass perpendicular to the ridges. Knoop hardness was determined by loading each specimen face 5 times for 15 seconds with a force of 50g. A scanning electron microscope was used to evaluate the surface of specimens in each treatment subgroup. Conclusions: The obtained results were as follows: 1. 3 types of die stone evaluated in this study did not show significant differences in surface hardness and abrasive resistance(P<.05). 2. In the abrasive resistance test, there were no significant differences between GC FUJIROCK(R) EP and MG Crystal Rock with or without 2 die hardener(P<.05). 3. Super plumstone treated with Stone die & plaster hardener showed increased wear loss(P<.05). 4. Die hardener coatings used in this study decreased the surface hardness of the gypsum material(P<.05).