RESUMEN
OBJECTIVE: The fracture toughness of dentin is critical to the prevention of tooth fracture. Within the tooth crown, the mechanical properties of dentin are influenced by spatial variations in the density and diameter of the dentin tubules with distance from the pulp. There are also relevant changes to the microstructure of dentin with age. In this investigation the importance of tubule density to the fracture toughness of dentin was evaluated in "young" and "old" age groups. METHODS: The variations in microstructure (density and diameter of tubules) from young and old donor teeth were studied by means of optical microscopy. RESULTS: A reduction in the density and diameter of tubules was identified to occur with aging. An approach previously proposed to study the mechanical behavior of porous materials was used to model the fracture toughness of coronal dentin in terms of the tubule characteristics. Results were then compared with published results from previous studies. CONCLUSIONS: The model predictions were consistent with experimental results for the fracture toughness of dentin from young donor teeth, but overestimated the values that have been reported for "old" dentin.
Asunto(s)
Dentina/química , Dentina/fisiología , Modelos Biológicos , Fracturas de los Dientes , Adolescente , Adulto , Anciano , Pulpa Dental , Femenino , Dureza/fisiología , Humanos , Masculino , Ensayo de Materiales , Persona de Mediana Edad , Tercer Molar , Porosidad , Diente , Corona del Diente/química , Corona del Diente/fisiología , Adulto JovenRESUMEN
UNLABELLED: Crown discoloration can be induced by root canal sealer remnants following root canal treatment. OBJECTIVE: The aim of this study was to evaluate chromatic alterations in human tooth crowns induced by a Mineral Trioxide Aggregate-based sealer (MTA Fillapex®) and a commonly used ZnOE-based sealer (Roth-811). The tested null hypothesis was that the application of the materials did not induce clinically perceptible crown discoloration (Ho: CIE color difference ΔE<3.7). MATERIAL AND METHODS: Forty five fully developed, intact, mandibular third molars were sectioned 1 mm below the cemento-enamel junction. The pulp chambers were chemomechanically debrided via the cervical access. The specimens were randomly assigned into three groups Group 1: MTA Fillapex, Group 2: Roth 811, Group 3: Negative control (unfilled) and immersed in individually marked vials containing distilled water up to the cervix (37±1°C). The spectral reflectance lines were recorded by utilizing a UV-VIS spectrophotometer equipped with integration sphere in the visual spectrum at baseline, 1 week, 1 and 3 months after material placement. Data were transformed into values of the CIE L*a*b* color system and the corresponding ΔE values were calculated. Statistical analysis was performed using two-way mixed ANOVA models, at p=0.05 level of significance. RESULTS: A statistically significant increase in a* and b* chromatic parameters of the MTA Fillapex Group was measured. However, ΔE values did not exceed the human eye perceptibility threshold (set at ΔE<3.7) during the experimental period (ΔEt3=2.88). In Roth-811 Group, a statistically significant decrease in L* and a statistically significant increase in a* and b* chromatic parameters was measured, during all observation periods. Resultant ΔE values exceeded the human eye perceptibility threshold after 1 week (ΔEt1=5.65). CONCLUSIONS: Application of MTA Fillapex in tooth crowns resulted in minimal color alterations, while Roth 811 induced severe discoloration, in vitro. It could be suggested that, in terms of aesthetics, the use of MTA Fillapex appears to be favorable.
Asunto(s)
Compuestos de Aluminio/química , Compuestos de Calcio/química , Óxidos/química , Materiales de Obturación del Conducto Radicular/química , Silicatos/química , Corona del Diente/efectos de los fármacos , Decoloración de Dientes/inducido químicamente , Cemento de Óxido de Zinc-Eugenol/química , Compuestos de Aluminio/efectos adversos , Análisis de Varianza , Compuestos de Calcio/efectos adversos , Color , Combinación de Medicamentos , Humanos , Ensayo de Materiales , Óxidos/efectos adversos , Valores de Referencia , Materiales de Obturación del Conducto Radicular/efectos adversos , Silicatos/efectos adversos , Espectrofotometría Ultravioleta , Factores de Tiempo , Corona del Diente/química , Cemento de Óxido de Zinc-Eugenol/efectos adversosRESUMEN
Crown discoloration can be induced by root canal sealer remnants following root canal treatment. Objective: The aim of this study was to evaluate chromatic alterations in human tooth crowns induced by a Mineral Trioxide Aggregate-based sealer (MTA Fillapex®) and a commonly used ZnOE-based sealer (Roth-811). The tested null hypothesis was that the application of the materials did not induce clinically perceptible crown discoloration (Ho: CIE color difference ΔE<3.7). Material and Methods: Forty five fully developed, intact, mandibular third molars were sectioned 1 mm below the cemento-enamel junction. The pulp chambers were chemomechanically debrided via the cervical access. The specimens were randomly assigned into three groups Group 1: MTA Fillapex, Group 2: Roth 811, Group 3: Negative control (unfilled) and immersed in individually marked vials containing distilled water up to the cervix (37±1°C). The spectral reflectance lines were recorded by utilizing a UV-VIS spectrophotometer equipped with integration sphere in the visual spectrum at baseline, 1 week, 1 and 3 months after material placement. Data were transformed into values of the CIE L*a*b* color system and the corresponding ΔE values were calculated. Statistical analysis was performed using two-way mixed ANOVA models, at p=0.05 level of significance. Results: A statistically significant increase in a* and b* chromatic parameters of the MTA Fillapex Group was measured. However, ΔE values did not exceed the human eye perceptibility threshold (set at ΔE<3.7) during the experimental period (ΔEt3=2.88). In Roth-811 Group, a statistically significant decrease in L* and a statistically significant increase in a* and b* chromatic parameters was measured, during all observation periods. Resultant ΔE values exceeded the human eye perceptibility threshold after 1 week (ΔEt1=5.65). Conclusions: Application of MTA Fillapex in tooth crowns resulted in minimal color alterations, while Roth 811 induced severe discoloration, in vitro. It could be suggested that, in terms of aesthetics, the use of MTA Fillapex appears to be favorable.
Asunto(s)
Humanos , Compuestos de Aluminio/química , Compuestos de Calcio/química , Óxidos/química , Materiales de Obturación del Conducto Radicular/química , Silicatos/química , Corona del Diente/efectos de los fármacos , Decoloración de Dientes/inducido químicamente , Cemento de Óxido de Zinc-Eugenol/química , Análisis de Varianza , Compuestos de Aluminio/efectos adversos , Color , Compuestos de Calcio/efectos adversos , Combinación de Medicamentos , Ensayo de Materiales , Óxidos/efectos adversos , Valores de Referencia , Materiales de Obturación del Conducto Radicular/efectos adversos , Espectrofotometría Ultravioleta , Silicatos/efectos adversos , Factores de Tiempo , Corona del Diente/química , Cemento de Óxido de Zinc-Eugenol/efectos adversosRESUMEN
PURPOSE: To determine the effect of acid etching time on dentin calcium solubilization and to compare the solubilization rate of primary and permanent dentin when etched for the same period of time. METHODS: Flat coronal dentin surfaces were produced on primary (n=8) and permanent (n=8) sound teeth. Three 2 mm-diameter areas were delimited on each surface and assigned to 5, 10 or 15 seconds of acid etching. Five microliters of 35% H3PO4 were applied on each area during the preset times, and 4 microL were retrieved for analysis. The amount of calcium was determined colorimetrically using Arsenazo III reagent and expressed as microg Ca/mm2 of dentin. Data were subjected to two-way ANOVA, Tukey's test and linear regression (alpha=5%). RESULTS: For both primary and permanent dentin, a statistically significant correlation was observed between acid etching time and calcium concentration (primary dentin R2 = 0.79; permanent dentin R2 = 0.73). Mean (sd) values of dissolved primary dentin after 5, 10 and 15 seconds were 1.00 (0.25), 1.74 (0.11) and 2.30 (0.42), whereas for permanent dentin the values were 0.47 (0.13), 0.89 (0.36) and 1.38 (0.20) microg Ca/mm2, respectively. Greater calcium solubilization (P<0.05) was detected for primary dentin than for permanent dentin after all acid etching times.
Asunto(s)
Grabado Ácido Dental , Permeabilidad de la Dentina , Solubilidad de la Dentina , Dentina/efectos de los fármacos , Diente Primario/química , Análisis de Varianza , Calcio/química , Dentina/química , Dentición Permanente , Humanos , Modelos Lineales , Ácidos Fosfóricos , Estadísticas no Paramétricas , Factores de Tiempo , Corona del Diente/químicaRESUMEN
OBJECTIVES: Considering the enamel chemical structure, especially carbonate band, which has a major role in the caries prevention, the objective of the present study was to assess the chemical alterations on the enamel irradiated with CO(2) laser by means of FTIR spectroscopy and SEM analysis. DESIGN: The enamel surfaces were analysed on a spectrometer for acquisition of the absorption spectrum relative to the chemical composition of the control sample. The irradiation was conducted with a 10.6-µm CO(2) laser (0.55W, 660W/cm(2)). The carbonate absorption band at 1600-1291cm(-1) as well as the water absorption band at 3793-2652cm(-1) was measured in each sample after the irradiation. The water band was measured again 24-h after the irradiation. The band area of each chemical compound was delimited, the background was subtracted, and the area under each band was integrated. Each area was normalized by the phosphate band (1190-702cm(-1)). RESULTS: There was a statistically significant decrease (p<0.05) in the water content after irradiation (control: 0.184±0.04; irradiated: 0.078±0.026), which increased again after rehydration (0.145±0.038). The carbonate/phosphate ratio was measured initially (0.112±0.029) and its reduction after irradiation indicated the carbonate loss (0.088±0.014) (p<0.05). CONCLUSION: The 10.6-µm CO(2) laser irradiation diminishes the carbonate and water contents in the enamel after irradiation.
Asunto(s)
Esmalte Dental/efectos de la radiación , Láseres de Gas , Agua Corporal/química , Carbonatos/análisis , Esmalte Dental/química , Esmalte Dental/ultraestructura , Humanos , Microscopía Electrónica de Rastreo , Tercer Molar , Fosfatos/análisis , Dosis de Radiación , Espectroscopía Infrarroja por Transformada de Fourier , Factores de Tiempo , Corona del Diente/química , Corona del Diente/efectos de la radiación , Corona del Diente/ultraestructuraRESUMEN
Proteins in mineralized tissues provide a window to the past, and dental enamel is peculiar in being highly resistant to diagenesis and providing information on a very narrow window of time, such as the developing period; however, to date, complete proteins have not been extracted successfully from ancient teeth. In this work we tested the ability of a whole-crown micro-etch technique to obtain enamel protein samples from mature enamel of recently extracted (n = 2) and ancient (n = 2; ad 800 to 1100) third molars. Samples were analyzed using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry, and the resulting spectra were searched against the Swiss-Prot protein database using the Mascot software for protein identification. In our protocol, the separation of proteins in gel is not necessary. Successful identification of specific enamel proteins was obtained after whole-crown superficial enamel etching with 10% HCl. Most protein fragments recovered from dry teeth and mummy teeth contained amino-terminal amelogenin peptides. Only one peptide specific for the amelogenin X-isoform was identified. In conclusion, the reported techniques allowed the successful recovery of proteins specific to dental enamel from samples obtained in a very conservative manner, which may also be important in forensic and/or archeological science.
Asunto(s)
Proteínas del Esmalte Dental/análisis , Grabado Dental/métodos , Corona del Diente/química , Amelogenina/análisis , Bases de Datos de Proteínas , Proteínas del Esmalte Dental/historia , Historia Medieval , Humanos , Diente Molar/química , Paleodontología/métodos , Mapeo Peptídico/métodos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , SueciaRESUMEN
This experiment aimed at evaluating, in vitro, the chromatic alteration of dental crowns submitted to internal bleaching. Color alterations were evaluated by means of spectrophotometric analysis and visual observation, at the following experimental phases: initial reading (LI), after-darkening reading (LE), immediate after-bleaching reading (LC), bleaching checked after 15 days (LC15) and after 30 days (LC30). After finding the values of L* (luminosity), a* and b* (shade and saturation), which made it possible to quantify the chromatic alterations of the specimens, color differences (deltaE ) were assessed by means of the CIE Lab Program. The statistical analysis of the results did not reveal any significant difference between conventional bleaching and bleaching activated by Er:YAG laser. No statistical difference was observed between the results after 15 and 30 days, for both experimental groups.
Asunto(s)
Calor/uso terapéutico , Terapia por Láser , Blanqueamiento de Dientes/métodos , Corona del Diente/química , Análisis de Varianza , Color , Diente Canino , Humanos , Técnicas In Vitro , Espectrofotometría , Factores de Tiempo , Resultado del TratamientoRESUMEN
The utilization of dentifrices with low fluorine concentration, for children under 6 years of age, has been suggested to reduce the risks of dental fluorosis. However, in order to have anticariogenic potential, the dentifrice should form loosely-bound fluorine (CaF2) on dental enamel. Considering that the formation of CaF2 is a function inversely related to pH, dentifrices with pH 5.5, with 275, 550 and 1,100 ppm F (NaF/silica) were developed in order to assess dose-response effects. A comparison between those dentifrices, a placebo product and the Crest toothpaste (positive control - standard) was carried out. Furthermore, the bioavailability of dentifrices, in terms of formation of total fluorine (TF), CaF2, and fluorapatite (FA) on human dental enamel, was evaluated. An ion-specific electrode was utilized for the determination of the dosage of fluorine. The results revealed that the dentifrice with 550 ppm F was more effective than both the placebo and the dentifrice with 275 ppm, presenting no difference in relation to the positive control (p > 0.05). A dose-effect correlation was observed as to the CaF2 formed. In conclusion, the modified formulation with 550 ppm F can be considered as effective as the standard dentifrice with 1,100 ppm, and its utilization would be safer with regard to dental fluorosis.
Asunto(s)
Caries Dental/prevención & control , Esmalte Dental/efectos de los fármacos , Flúor/farmacología , Fluorosis Dental/prevención & control , Pastas de Dientes/farmacología , Apatitas/análisis , Apatitas/farmacología , Sustitutos de Huesos/análisis , Sustitutos de Huesos/farmacología , Preescolar , Esmalte Dental/química , Relación Dosis-Respuesta a Droga , Fluoruros/análisis , Fluoruros/farmacología , Flúor/análisis , Humanos , Tercer Molar , Corona del Diente/química , Corona del Diente/efectos de los fármacos , Pastas de Dientes/químicaRESUMEN
The cellular distribution and changes of sugar residues during tooth development in embryos of the rabbit Oryctolagus cuniculus were investigated by using horseradish peroxidase-conjugated lectins (lectin-HRP). The lectins SBA, ECA, and LTA show no binding to any region of the dental cap and bell stages, whereas BS-1 and UEA-1 bind to dental cells at both stages. Appropriate control studies confirmed the specificity of the binding of the lectins. At cap stage, the lectins BS-1 and UEA-1 show moderate binding to the (pre)-ameloblast and (pre)-odontoblast cells. These results suggest that the acetylgalactosamine and alpha-L-fucose residues present in (pre)-ameloblasts and (pre)-odontoblasts, respectively, are common to determined but relatively undifferentiated cells capable of forming matrices of hard tissues. Since the odontoblast and ameloblast express dentin and enamel, respectively, it can be speculated that the abundance of these residues in these cells might be associated with the maintenance of the capacity of the cells to produce such matrices. At the bell stage, the odontoblasts display considerable amounts of alpha-L-fucose, whereas alpha-L-fucose is poorly localized in ameloblasts. However, ameloblasts contain significant quantities of N-acetylgalactosamine, whereas only a diffuse positivity for this carbohydrate is apparent in odontoblasts. The marked changes of the glycosylation pattern of these glycoconjugates might indicate that they play a role during the cell-to-cell interaction and might also be involved in the odontoblastic and ameloblastic functional activity. Such a possibility is entirely speculative until specific in vitro experiments are conducted.