A confocal micro-endoscopic investigation of the relationship between the microhardness of carious dentine and its autofluorescence (original) (raw)
Related papers
Archives of Oral Biology, 1996
42onventional quasi-static and dynamic test methods have a number of limitations when used to measure the mechanical properties of enamel and dentine. These are due to the complex structure of the material and the small specimen size. In this investigation, a microindentation technique was used to measure the hardness and Young's modulus of human enamel and dentine and any variations with location. Freshly extracted molar teeth were sectioned, and the cut surfaces were ground and polished progressively to l pm. The polished surfaces were indented at different distances from the surface and amelodentinal junction with a Knoop indentor. Measurements of the length of the long indentation diagonal were used to calculate a value for hardness. It has been shown that the a-value for Young's modulus of a material can be calculated by comparing the ratio of the long and short diagonals on an indented specimen with the actual ratio of the indentor as any changes will be due to elastic recovery in the specimen. Values obtained for the Knoop hardness of enamel and dentine were in good agreement with those of other workers. It was also possible to show that there was a decrease in hardness with depth from the surface in enamel. The hardness of dentine increased with distance from the amelodentinal junction. Values for Young's modulus for dentine were in good agreement with those of other workers, and there was an increase in modulus with depth from the amelodentinal junction from 8.7 to I 1.2 GNm-2 Values for Young's modulus of enamel were not as easy to calculate because of surface-and subsurface damage.
Journal of Clinical and Experimental Dentistry
Background: To compare the fluorescence-aided and conventionally excavated dentin with microhardness and shear bond strength(SBS) tests. Material and Methods: Twenty-four teeth with dentin caries were bisected through the center of the lesion into two halves. Forty-eight dentin specimens were embedded and mounted in an acrylic resin. All carious tissue was removed and classified as caries free using conventional visual tactile criteria. Then half of the specimens(n=24) were reinspected with fluorescence-aided caries excavation light(FACE) (FaceLight, W&H Dentalwerk, Bürmoos GmbH, Austria). Specimens were subjected to microhardness and shear bond strength testings. The fracture mode analysis was also performed. The data were compared with Student's t test and Chi-square test. Results: Residual caries was observed in 2 out of 24 conventionally excavated specimens with FACE inspection(p>0.05). Mean Vickers hardness of the dentin was 61.5±5 in the FACE group and 70.3±3 kg/mm2 in the conventionally excavated group(p>0.05). The mean SBS value of FACE group was 11.42±1.63 MPa and 18.27±1.43 MPa in conventionally excavated group. There was no statistically significant difference between conventional and FACE groups for microhardness and SBS tests(p>0.05). There were also no significant differences on the fracture mode distributions of the groups(p>0.05). Conclusions: FACE method could be considered as a promising technique for removing infected dentin.
SpringerPlus, 2016
Background: The aim of this in vitro study was to evaluate the microindentation hardness and chemical composition of residual dentin left at the cavity bottom following removal of carious dentin using the Carisolv chemomechanical and Er:YAG laser caries excavation methods in comparison with the conventional tungsten-carbide bur excavation. Methods: Sixty-nine extracted permanent teeth with occlusal dentin caries were assigned into three groups according to caries removal technique. Carious dentin excavation was guided by tactile method and a caries-staining dye. In stereomicroscope images (100×) of the samples, the presence or absence of residual caries was defined. The Knoop hardness value of the cavity floor was determined and atomic analysis of treated cavities was performed by energy dispersive X-ray spectroscopy. Results: The Knoop hardness value of residual dentin left at the cavity bottom was lower (One-way ANOVA, Dunnett-C, p < 0.05) and the percentage of samples with remaining carious dentin was higher after Carisolv excavation than those obtained after conventional and laser excavations (Kruskal-Wallis, Mann-Whitney U, p < 0.05). No significant differences were found between the quantities of calcium content (Ca wt%), phosphorus content (P wt%) and calcium/phosphorus ratio of the cavities treated by three techniques (Kruskal-Wallis, Mann-Whitney U, p > 0.05). Conclusion: The results indicated that Er:YAG laser was more comparable to conventional bur excavation than chemomechanical method in the efficacy of caries removal with regard to microindentation hardness of remaining dentin and both Carisolv gel and Er:YAG laser did not alter chemical composition of residual dentin in the treated cavities.
Significance: The increase in root caries is a serious problem as society ages. Root caries is diagnosed by inspection and palpation, which are qualitative. A method to objectively and quantitatively evaluate the progress of root caries in a clinical setting is strongly desired. The root caries could be diagnosed by measuring hardness because dentin becomes softer as the caries progresses. Vickers hardness has been customarily used as an indicator of tooth hardness. However, this method cannot be used to in vivo teeth because the teeth must be dried prior to measurement to make the indentation. A hardness meter using an indenter with light for tooth monitoring (HAMILTOM) is proposed as an optical device. HAMILTOM could measure hardness of teeth in wet condition as a dark area while applying a load to dentins without drying. Therefore, HAMILTOM may realize hardness measurements of in vivo teeth in a clinical setting quantitatively. Aim: The aim of our study is to demonstrate the optical dentin hardness measuring device HAMILTOM using bovine dentin with different demineralization times and to evaluate the correlation between the dark areas measured by HAMILTOM and the Vickers hardness measured by the Vickers hardness tester. Approach: The samples were 20 bovine dentins. They were demineralized by a lactic acid solution with different times and divided into groups 1 and 2 of 10 samples each. In both groups, the dark areas and Vickers hardness were measured for each sample. Group 1 was used to obtain a calibration curve to calculate Vickers hardness from the dark area. Group 2 was used to validate the calibration curve obtained from the dentin samples of group 1. Results: The areas appearing black without a total internal reflection of the indenter measured by HAMILTOM increased as the demineralization time increased. Additionally, the Vickers hardness of group 2 calculated by the dark areas of group 2 and the calibration curve obtained in group 1 and the Vickers hardness of group 2 measured by the Vickers hardness tester were strongly correlated with a determination coefficient of 0.99. Conclusions: The results demonstrate that HAMILTOM may be a suitable alternative to the conventional method. Unlike the conventional method, which cannot be used for in vivo teeth, HAMILTOM holds potential to quantitatively evaluate the progress of caries in in vivo teeth.
Microhardness of dentine in primary teeth after topical fluoride applications
Journal of Dentistry, 2008
Dentine Fluoride a b s t r a c t Objectives: This study measured the microhardness of arrested dentinal caries on primary teeth receiving regular fluoride applications after 30 months. Methods: Caries on primary upper anterior teeth of preschool children were randomly assigned to receive 38% silver diamine fluoride every 12 months or 5% sodium fluoride varnish every 3 months. Lesions that were hard on probing were considered arrested. At 30 months, very mobile teeth were extracted, sectioned, and polished and they underwent Knoop hardness number (KHN) measurements at sites below the surface at the center of the carious lesion every 25 mm toward the pulp. Three sets of measurements were made on parallel tracks approximately 150-200 mm apart, and the median KHN at each depth were analyzed. Results: Five arrested and five soft carious lesions were examined. Within the outer 25-200 mm, the median KHN of arrested carious lesions (range, 20-46 or 196-451 MPa) were greater than those of soft carious lesions (range,. The difference between them, however, was not statistically significant. At a distance of 225 mm or more from the surface of the lesion, the median KHN of both groups were between 20 and 30 .
Microhardness of the enamel exposed to whitening dentifrices
Revista de Odontologia da Universidade Cidade de São Paulo, 2017
Introduction: The purpose of this study is to verify the effect of three different types of dentifrices on the superficial microhardness of bovine enamel. Methods: Forty-eight 4x4mm dental fragments were polished and randomly divided into 4 groups: GI, conventional silica-based dentifrice; GII, hydrogen peroxide-based dentifrice; GIII, carbamide peroxide-based dentifrice; and GIV, immersion in artificial saliva. After polished, the specimens received five indentations of 25g static load, for 5 seconds. Subsequently, specimens from groups GI, GII and GIII were immersed in solution containing dentifrice and distilled water, in weight proportion of 1:2, for 15 minutes daily. After this period, fragments were rinsed in tap water and stored in artificial saliva at 37oC. This procedure was repeated for 21 days and then a new analysis of the microhardness was performed. Results and conclusion: The results were submitted to ANOVA and Fisher’s test at 5%. It was concluded that all samples tr...
Caries Research, 2013
correlation analysis (p ! 0.05). The in situ model produced a deep lesion with a high R value, but with a thin surface layer. Regarding the in vitro models, MC gel produced only a shallow lesion, while buffers I and II as well as TEMDP induced a pronounced subsurface lesion with deep demineralization. The relationship between CSH and TMR was weak and not linear. The artificial dentine carious lesions induced by the different models differed significantly, which in turn might influence further de-and remineralization processes. Hardness analysis should not be interpreted with respect to dentine mineral loss.
Microhardness of superficial and deep sound human dentin
Journal of Biomedical Materials Research, 2003
Our purpose in this study was to determine the microhardness of superficial and deep dentin by means of two indentation methods (Knoop and Vickers) under two different applied loads. Twelve dentin discs approximately 2-mm thick were obtained from both superficial and deep dentin by transversally sectioning the crowns of sound, extracted human third molars with a diamond blade under water irrigation. Dentin surfaces were sequentially polished, and indentations (n ϭ 20 per surface) were performed with either Vickers indentor at loads of 300 and 500 g, respectively, or Knoop indentor at loads of 50 and 100 g, respectively. Average Vickers hardness number (VHN) and Knoop hardness number (KHN) were calculated and treated with two-way analysis of variance (ANOVA) and Student's t test. Microhardness of dentin was not influenced by the different loads applied for both indentation methods. Knoop hardness was significantly higher for superficial than for deep dentin (p Ͻ 0.05). Conversely, Vickers hardness was not significantly different for both substrates (p Ͼ 0.05). Differences in dentin hardness as a function of depth exist, but they might not be relevant, and no alteration of the distribution of stresses along the adhesive interface is expected.