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Thomas Attin - One of the best experts on this subject based on the ideXlab platform.
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MMP-9 in Dentinal Fluid correlates with caries lesion depth
Caries research, 2017Co-Authors: Vasudev Ballal, Sheetal Rao, Azadeh Bagheri, Vinutha Bhat, Thomas Attin, Matthias ZehnderAbstract:The analysis of molecular cues in Dentinal Fluid from an excavated cavity could improve diagnostics in the context of minimally invasive caries treatment. In the current clinical trial we assessed whether the Dentinal Fluid levels of MMP-9 (matrix metalloproteinase-9; neutrophil gelatinase) would increase with the progression of carious lesions. MMP-9 is associated with neutrophil-related tissue breakdown in the pulp. Absolute MMP-9 levels were contrasted against the levels of MMP-2, an enzyme related to normal tissue turnover. Dentinal Fluid was collected below deep and shallow caries from molars and premolars within the same patients aged 18 years and older (n = 30, 1 tooth per group/patient). Experimental teeth were isolated under a rubber dam prior to excavation. Dentinal Fluid was collected from the bottom of the cavity using a size 25 paper point. MMP levels were assessed using an enzyme-linked immunosorbent assay. Nonparametric methods were applied to test for differences between groups. Significantly more (p < 0.05, Wilcoxon test) MMP-9 was collected from the deep carious lesions than from the shallow counterparts. Pairwise comparison of MMP-9 values within patients revealed that there was more MMP-9 collected from deep lesions than from shallow counterparts in 27 of the 30 individuals under investigation (pairwise Wilcoxon test, p < 0.001). In contrast, no such difference existed for MMP-2. There was a high correlation between MMP-9 from deep and shallow lesions (Spearman's ρ = 0.72, p < 0.001), indicating that patients with more MMP-9 in the deep carious lesion also tended to have more MMP-9 in the shallow lesion.
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Development and validation of an in vitro model for measurements of cervical root dentine permeability
Clinical Oral Investigations, 2014Co-Authors: Holger Jungbluth, Thomas Attin, Wolfgang BuchallaAbstract:Objectives The aim of this series of studies was the development and validation of a new model for evaluation of Dentinal hypersensitivity (DH) therapies. Materials and methods Roots from extracted human teeth were sealed with a flowable composite. In the cervical area, a 3-mm-wide circular window was ground through the seal 1 mm deep into dentine. The pulp lumen was connected to a reservoir of artificial Dentinal Fluid (ADF) containing protein, mineral salts and methylene blue. At increased pulpal pressure, the ADF released through the said window was collected in containers each with 20 ml of physiologic saline for a consecutive series of 30-min intervals and ADF concentration (absorption) was determined photometrically. The model was verified by three experiments. In experiment 1, the lower limit of quantification (LLoQ, coefficient of variation = 20 % and difference of 5 standard deviations (SD) from blank) of ADF in physiologic saline was determined by measuring the absorption of 15 dilutions of ADF in physiologic saline (containing 0.625 ng to 12.5 μg methylene blue/ml) photometrically for ten times. In experiment 2, long-term linearity of ADF perfusion/outflow was investigated using 11 specimens. The ADF released through the window was collected in the said containers separately for each consecutive interval of 30 min for up to 240 min. Absorption was determined and analysed by linear regression over time. In experiment 3, perfusion before (2×) and after single treatment according to the following three groups was measured: BisGMA-based sealant (Seal&Protect®), an acidic fluoride solution (elmex Fluid®) and control (no treatment). Results In experiment 1, the LLoQ was 0.005 μg methylene blue/ml. In experiment 2, permeability was different within the specimens and decreased highly linearly with time, allowing the prediction of future values. In experiment 3, Seal&Protect® completely occluded Dentinal tubules. elmex Fluid® increased tubular permeability by about 30 % compared to control. Conclusions A model comprising the use of artificial Dentinal Fluid was developed and validated allowing screening of therapeutic agents for the treatment of DH through reliable measurement of permeability of cervical root dentine. Clinical relevance The described in vitro model allows evaluation of potential agents for the treatment of DH at the clinically relevant cervical region of human teeth.
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comparison of vehicles to collect Dentinal Fluid for molecular analysis
Journal of Dentistry, 2014Co-Authors: Matthias Zehnder, Dan-krister Rechenberg, Nagihan Bostanci, Filiz Sisman, Thomas AttinAbstract:OBJECTIVES To test the hypothesis that a material with higher water absorption than polyvinylidene fluoride (PVDF) could increase the yield of target molecules from exposed dentine. METHODS In a series of standard tests, different cellulose membranes were compared to a PVDF counterpart for their ability to absorb water and release protein. In a subsequent randomized clinical trial, the cellulose material with the most favourable values was compared to PVDF regarding the levels of MMP-2 that could be collected from exposed dentine of healthy human teeth during filling replacement. MMP-2 levels were determined by enzyme-linked immunosorbent assay (ELISA). Data from the laboratory experiments were compared between materials using the appropriate parametric tests. The frequency of cases yielding quantifiable levels of MMP-2 was compared between materials by Fisher's exact test. The level of significance was set at 5%. RESULTS The cellulose membrane with the largest pore size (12-15μm) absorbed significantly (P<0.05) more water than PVDF. It showed a protein release that was similar to that of PVDF, while the cellulose membranes with smaller pore size retained significantly more protein (P<0.05). Using the large-pore cellulose membrane, MMP-2 could be collected at a quantifiable level from the dentine of healthy teeth in 9 of 13 cases, compared to 1 of 13 with the PVDF membrane (P<0.05). CONCLUSIONS Under the current conditions, a large-pore cellulose membrane yielded more of a molecule of diagnostic value compared to a standard PVDF membrane. CLINICAL SIGNIFICANCE Molecular diagnostics of Dentinal Fluid are hampered by low yields. In the current study, it was shown that cellulose membranes are more useful to collect MMP-2 from Dentinal Fluid than PVDF membranes.
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Comparison of vehicles to collect Dentinal Fluid for molecular analysis
Journal of dentistry, 2014Co-Authors: Matthias Zehnder, Dan-krister Rechenberg, Nagihan Bostanci, Filiz Sisman, Thomas AttinAbstract:To test the hypothesis that a material with higher water absorption than polyvinylidene fluoride (PVDF) could increase the yield of target molecules from exposed dentine. In a series of standard tests, different cellulose membranes were compared to a PVDF counterpart for their ability to absorb water and release protein. In a subsequent randomized clinical trial, the cellulose material with the most favourable values was compared to PVDF regarding the levels of MMP-2 that could be collected from exposed dentine of healthy human teeth during filling replacement. MMP-2 levels were determined by enzyme-linked immunosorbent assay (ELISA). Data from the laboratory experiments were compared between materials using the appropriate parametric tests. The frequency of cases yielding quantifiable levels of MMP-2 was compared between materials by Fisher's exact test. The level of significance was set at 5%. The cellulose membrane with the largest pore size (12-15μm) absorbed significantly (P<0.05) more water than PVDF. It showed a protein release that was similar to that of PVDF, while the cellulose membranes with smaller pore size retained significantly more protein (P<0.05). Using the large-pore cellulose membrane, MMP-2 could be collected at a quantifiable level from the dentine of healthy teeth in 9 of 13 cases, compared to 1 of 13 with the PVDF membrane (P<0.05). Under the current conditions, a large-pore cellulose membrane yielded more of a molecule of diagnostic value compared to a standard PVDF membrane. Molecular diagnostics of Dentinal Fluid are hampered by low yields. In the current study, it was shown that cellulose membranes are more useful to collect MMP-2 from Dentinal Fluid than PVDF membranes. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Development and validation of an in vitro model for measurements of cervical root dentine permeability.
Clinical oral investigations, 2014Co-Authors: Holger Jungbluth, Thomas Attin, Wolfgang BuchallaAbstract:The aim of this series of studies was the development and validation of a new model for evaluation of Dentinal hypersensitivity (DH) therapies. Roots from extracted human teeth were sealed with a flowable composite. In the cervical area, a 3-mm-wide circular window was ground through the seal 1 mm deep into dentine. The pulp lumen was connected to a reservoir of artificial Dentinal Fluid (ADF) containing protein, mineral salts and methylene blue. At increased pulpal pressure, the ADF released through the said window was collected in containers each with 20 ml of physiologic saline for a consecutive series of 30-min intervals and ADF concentration (absorption) was determined photometrically. The model was verified by three experiments. In experiment 1, the lower limit of quantification (LLoQ, coefficient of variation = 20 % and difference of 5 standard deviations (SD) from blank) of ADF in physiologic saline was determined by measuring the absorption of 15 dilutions of ADF in physiologic saline (containing 0.625 ng to 12.5 μg methylene blue/ml) photometrically for ten times. In experiment 2, long-term linearity of ADF perfusion/outflow was investigated using 11 specimens. The ADF released through the window was collected in the said containers separately for each consecutive interval of 30 min for up to 240 min. Absorption was determined and analysed by linear regression over time. In experiment 3, perfusion before (2×) and after single treatment according to the following three groups was measured: BisGMA-based sealant (Seal&Protect®), an acidic fluoride solution (elmex Fluid®) and control (no treatment). In experiment 1, the LLoQ was 0.005 μg methylene blue/ml. In experiment 2, permeability was different within the specimens and decreased highly linearly with time, allowing the prediction of future values. In experiment 3, Seal&Protect® completely occluded Dentinal tubules. elmex Fluid® increased tubular permeability by about 30 % compared to control. A model comprising the use of artificial Dentinal Fluid was developed and validated allowing screening of therapeutic agents for the treatment of DH through reliable measurement of permeability of cervical root dentine. The described in vitro model allows evaluation of potential agents for the treatment of DH at the clinically relevant cervical region of human teeth.
Ivo Krejci - One of the best experts on this subject based on the ideXlab platform.
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Marginal seal stability of one bottle adhesives in Class V vs. Class I cavities
Clinical Oral Investigations, 2011Co-Authors: Juan R. Mayoral, Ladislav Gregor, Edson A. Campos, Miguel Roig, Ivo KrejciAbstract:The aim of this study was to test the influence of two different cavity configurations on marginal stability of recent one bottle “etch & rinse” and “self-etch” adhesives in Class V vs. Class I cavities, before and after thermo-mechanical loading under simulation of Dentinal Fluid. Forty human upper molars were selected and assigned to five experimental groups. Intrapulpal pressure was maintained during cavity preparation, restoration placement, finishing and stressing. Standardized Class I and V-Shaped Class V cavities were prepared on each tooth. Half of the margins of Class V cavities were located in enamel and half in dentin. All cavities were restored with different adhesives systems and a nano-hybrid composite. Materials were light-cured using a LED unit. Restored teeth were loaded in a computer-controlled chewing machine with 1.2 million mechanical occlusal cycles simultaneously with 3,000 thermal cycles (5–50–5°C). Impressions were made with polyvinylsiloxane of each restoration before and after loading. Gold-coated epoxy replicas were prepared for SEM examination at ×200 magnification. Significant differences between materials were found both before and after loading (Kruskal–Wallis, Bonferroni, p
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Single-bottle adhesives behave as permeable membranes after polymerization. I. In vivo evidence.
Journal of dentistry, 2004Co-Authors: Franklin R. Tay, Ivo Krejci, Serge Bouillaguet, David H. Pashley, Roland Frankenberger, Ricardo M. Carvalho, C. N. S. LaiAbstract:This study tested the hypothesis that single-bottle total-etch adhesives are effective in reducing dentine permeability under in vivo conditions. Crown preparations on vital human teeth were performed under local analgesia as part of the treatment plan for prosthetic rehabilitation. Four single-bottle adhesives (Single Bond, 3M ESPE; Excite DSC, Ivoclar Vivadent; Prime and Bond NT Dual-Cure, Dentsply DeTrey and One-Step, Bisco Inc.) were applied to the cut dentine after acid-etching. Polyvinyl siloxane impressions were taken, using an ultra-low viscosity impression material, of the smear layer-covered dentine before applying the adhesives to deep vital dentine, and after adhesive placement. Additional impressions were taken of the adhesive-sealed dentine following the removal of the provisional prostheses after a 7-10 day period. Epoxy resin replicas of the crown preparations were examined with scanning electron microscopy to evaluate the extent of Dentinal Fluid transudation during pre-bonded, immediately bonded and post-bonded periods. Dentinal Fluid transudation from localised areas that were close to the dental pulp was universally observed from all epoxy resin replicas, irrespective of the adhesive employed. The transudation of Dentinal Fluid from the control smear layer-covered dentine of each crown preparation was comparatively mild when compared to the extent that was observed after total-etching and application of the single-bottle adhesive. Dentinal Fluid droplets were specifically located over the surface of the adhesive layer. Continuous transudation of Dentinal Fluid occurred even after the removal of the provisional prostheses, and was considerably more profuse in subjects who opted for the fitting of the permanent prostheses without the use of a local anaesthetic solution. Single-bottle adhesives, because of their lack of a comparatively more hydrophobic bonding resin layer, behave as permeable membranes after polymerisation. They permit the continuous transudation of Dentinal Fluid and do not provide a hermetic seal in vital deep dentine. Although the relatively slow rate of diffusion of Dentinal Fluid is unlikely to result in post-operative cold sensitivity, it may interfere with the optimal polymerisation of dual-cured or auto-cured composites or resin cements in both direct and indirect restorations.
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The ultrastructure of a compomer adhesive interface in enamel and dentin, and its marginal adaptation under Dentinal Fluid as compared to that of a composite.
Dental Materials, 1999Co-Authors: Ivo Krejci, F. Balmelli, Peter Schupbach, F. LutzAbstract:Objectives: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. Methods: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated Dentinal Fluid before and after simultaneous mechanical and thermal loading. Results: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of “continuous margin” in the enamel marginal area before loading, and in the dentin area before and after loading (p
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the ultrastructure of a compomer adhesive interface in enamel and dentin and its marginal adaptation under Dentinal Fluid as compared to that of a composite
Dental Materials, 1999Co-Authors: Ivo Krejci, F. Balmelli, Peter Schupbach, F. LutzAbstract:Objectives: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. Methods: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated Dentinal Fluid before and after simultaneous mechanical and thermal loading. Results: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of “continuous margin” in the enamel marginal area before loading, and in the dentin area before and after loading (p<0.05; unpaired t-test). Only after loading, the percentage of “continuous margin” in enamel was significantly (p<0.05; unpaired t-test) better than that of the compomer. Significance: The results indicated that the ultrastructure of the adhesive interface allowed no clear conclusions to be drawn as to the quality of marginal adaptation.
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New adhesives in Class V restorations under combined load and simulated Dentinal Fluid
Dental materials : official publication of the Academy of Dental Materials, 1994Co-Authors: Ivo Krejci, Tobias Häusler, David Sägesser, Felix LutzAbstract:Objectives. This study compared the efficacy of three Dentinal adhesives using the “all etch” technique (All-Bond 2, Bisco; Scotchbond MP, 3M Dental Products Co.; OptiBond, Kerr) with a Dentinal adhesive which still uses phosphoric acid to condition enamel and a self-etching primer for dentin (A.R.T.-Bondm, Coltene/Whaledent). Methods. Eight V-shaped mixed Class V restorations were placed per group in extracted human premolars. The restorations were subjected to 1,200,000 mechanical occlusal cycles (max. force 49 N; frequency 1.7 Hz) and 3,000 simultaneous thermal cycles (5-50-5°C). Dentinal Fluid was simulated using 1:3 diluted horse serum and fed into the pulp chamber both during restoration and loading. Percentages of “continuous margin” were assessed on SEM replicas of enamel and Dentinal margins at 200x magnification immediately before and after stressing, respectively. Results. No significant differences were observed before stress between the materials either in enamel or in dentin. After stress, however, OptiBond and A.R.T.-Bond performed significantly better in dentin than the two other adhesives (Kruskal-Wallis, Mann-Whitney; p < 0.05). Although high initial values were observed, All-Bond 2 and Scotchbond MP were not stress-resistant under simulated physiological conditions. Significance. The predicted clinical potential of All-Bond 2 and Scotchbond MP is inferior to that of OptiBond and A.R.T.-Bond.
Min Lin - One of the best experts on this subject based on the ideXlab platform.
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Fluid dynamics analysis of shear stress on nerve endings in Dentinal microtubule a quantitative interpretation of hydrodynamic theory for dental pain
Journal of Mechanics in Medicine and Biology, 2011Co-Authors: Min LinAbstract:Noxious thermal and/or mechanical stimuli applied to dentine can cause Fluid flow in Dentinal microtubules (DMTs). The Fluid flow induces shear stress (SS) on intradental nerve endings and may excite pulpal mechanoreceptors to generate dental pain sensation. There exist numerous studies on dental thermal pain, but few are mathematical. For this, we developed a computational Fluid dynamics (CFD) model of Dentinal Fluid flow (DFF) in innervated DMTs. Based on this model, we systematically investigated the effects of various parameters (e.g., biological structure, DFF velocity, and Fluid properties) on the SS experienced by intradental nerve endings and thus provide a quantitative interpretation to the hydrodynamic theory. The dimensions of biological structures, odontoblastic process (OP) movement, Dentinal Fluid velocity, and viscosity were found to have significant influences on the SS while Dentinal Fluid density showed negligible influence under conditions studied. The results indicate that: (i) dental pain study of animal models may not be directly applied to human being and the results may even vary from one person to another and (ii) OP movement caused by DFF changes the dimension of the space for the Fluid flow, affecting thus the SS on nerve endings. The present work enables better understanding of the mechanisms underlying dental pain sensation and quantification of dental pain intensity resulted from clinical procedures such as dentine sensitivity testing and dental restorative processes.
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analysis of thermal induced Dentinal Fluid flow and its implications in dental thermal pain
Archives of Oral Biology, 2011Co-Authors: Min Lin, Shaobao Liu, Lin NiuAbstract:a b s t r a c t Objectives: The initiation of the pain sensation experienced following the thermal stimulation of dentine has been correlated with Fluid flow in the Dentinal tubules. There may be other mechanisms. Methods: This study examines this possibility using a mathematical model to simulate the temperature and thermal stress distribution in a tooth undergoing thermal stimulation. The results obtained were then used to predict the Fluid flow in a single Dentinal tubule by considering the deformation of the Dentinal tubules and Dentinal Fluid. Results: Deformation of the pulp chamber was observed before a noticeable temperature change was recorded at the dentine–enamel junction. Tubule deformation leads to changes in Fluid flow more rapidly than Fluid expansion or contraction. This finding agreed with previously reported experimental observations. An initially high rate of outward Fluid flow under cooling was found to correspond to short latency neural responses whilst heating was associated with long latency neural responses. Conclusion: Rapid Fluid flow caused by thermal deformation of Dentinal tubules may account for the short latency ( 10 s) neural responses could be associated with the activation of thermo-sensitive receptors.
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Fluid mechanics in Dentinal microtubules provides mechanistic insights into the difference between hot and cold dental pain.
PloS one, 2011Co-Authors: Min Lin, Zhengyuan Luo, Bofeng BaiAbstract:Dental thermal pain is a significant health problem in daily life and dentistry. There is a long-standing question regarding the phenomenon that cold stimulation evokes sharper and more shooting pain sensations than hot stimulation. This phenomenon, however, outlives the well-known hydrodynamic theory used to explain dental thermal pain mechanism. Here, we present a mathematical model based on the hypothesis that hot or cold stimulation-induced different directions of Dentinal Fluid flow and the corresponding odontoblast movements in Dentinal microtubules contribute to different dental pain responses. We coupled a computational Fluid dynamics model, describing the Fluid mechanics in Dentinal microtubules, with a modified Hodgkin-Huxley model, describing the discharge behavior of intradental neuron. The simulated results agreed well with existing experimental measurements. We thence demonstrated theoretically that intradental mechano-sensitive nociceptors are not “equally sensitive” to inward (into the pulp) and outward (away from the pulp) Fluid flows, providing mechanistic insights into the difference between hot and cold dental pain. The model developed here could enable better diagnosis in endodontics which requires an understanding of pulpal histology, neurology and physiology, as well as their dynamic response to the thermal stimulation used in dental practices.
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Analysis of thermal-induced Dentinal Fluid flow and its implications in dental thermal pain
Archives of oral biology, 2011Co-Authors: Min Lin, Shaobao Liu, Lin NiuAbstract:The initiation of the pain sensation experienced following the thermal stimulation of dentine has been correlated with Fluid flow in the Dentinal tubules. There may be other mechanisms. This study examines this possibility using a mathematical model to simulate the temperature and thermal stress distribution in a tooth undergoing thermal stimulation. The results obtained were then used to predict the Fluid flow in a single Dentinal tubule by considering the deformation of the Dentinal tubules and Dentinal Fluid. Deformation of the pulp chamber was observed before a noticeable temperature change was recorded at the dentine-enamel junction. Tubule deformation leads to changes in Fluid flow more rapidly than Fluid expansion or contraction. This finding agreed with previously reported experimental observations. An initially high rate of outward Fluid flow under cooling was found to correspond to short latency neural responses whilst heating was associated with long latency neural responses. Rapid Fluid flow caused by thermal deformation of Dentinal tubules may account for the short latency (<1s) activation of mechano-sensitive receptors after of cooling. Long latency (>10s) neural responses could be associated with the activation of thermo-sensitive receptors. Published by Elsevier Ltd.
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A review of heat transfer in human tooth--experimental characterization and mathematical modeling.
Dental materials : official publication of the Academy of Dental Materials, 2010Co-Authors: Min Lin, Bofeng BaiAbstract:With rapid advances in modern dentistry, high-energy output instruments (e.g., dental lasers and light polymerizing units) are increasingly employed in dental surgery for applications such as laser assisted tooth ablation, bleaching, hypersensitivity treatment and polymerization of dental restorative materials. Extreme high temperature occurs within the tooth during these treatments, which may induce tooth thermal pain (TTP) sensation. Despite the wide application of these dental treatments, the underlying mechanisms are far from clear. Therefore, there is an urgent need to better understand heat transfer (HT) process in tooth, thermally induced damage of tooth, and the corresponding TTP. This will enhance the design and optimization of clinical treatment strategies. This paper presents the state-of-the-art of the current understanding on HT in tooth, with both experimental study and mathematical modeling reviewed. Limitations of the current experimental and mathematical methodologies are discussed and potential solutions are suggested. Interpretation of TTP in terms of thermally stimulated Dentinal Fluid flow is also discussed.
F. Lutz - One of the best experts on this subject based on the ideXlab platform.
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The ultrastructure of a compomer adhesive interface in enamel and dentin, and its marginal adaptation under Dentinal Fluid as compared to that of a composite.
Dental Materials, 1999Co-Authors: Ivo Krejci, F. Balmelli, Peter Schupbach, F. LutzAbstract:Objectives: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. Methods: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated Dentinal Fluid before and after simultaneous mechanical and thermal loading. Results: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of “continuous margin” in the enamel marginal area before loading, and in the dentin area before and after loading (p
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the ultrastructure of a compomer adhesive interface in enamel and dentin and its marginal adaptation under Dentinal Fluid as compared to that of a composite
Dental Materials, 1999Co-Authors: Ivo Krejci, F. Balmelli, Peter Schupbach, F. LutzAbstract:Objectives: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. Methods: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated Dentinal Fluid before and after simultaneous mechanical and thermal loading. Results: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of “continuous margin” in the enamel marginal area before loading, and in the dentin area before and after loading (p<0.05; unpaired t-test). Only after loading, the percentage of “continuous margin” in enamel was significantly (p<0.05; unpaired t-test) better than that of the compomer. Significance: The results indicated that the ultrastructure of the adhesive interface allowed no clear conclusions to be drawn as to the quality of marginal adaptation.
Wolfgang Buchalla - One of the best experts on this subject based on the ideXlab platform.
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Development and validation of an in vitro model for measurements of cervical root dentine permeability
Clinical Oral Investigations, 2014Co-Authors: Holger Jungbluth, Thomas Attin, Wolfgang BuchallaAbstract:Objectives The aim of this series of studies was the development and validation of a new model for evaluation of Dentinal hypersensitivity (DH) therapies. Materials and methods Roots from extracted human teeth were sealed with a flowable composite. In the cervical area, a 3-mm-wide circular window was ground through the seal 1 mm deep into dentine. The pulp lumen was connected to a reservoir of artificial Dentinal Fluid (ADF) containing protein, mineral salts and methylene blue. At increased pulpal pressure, the ADF released through the said window was collected in containers each with 20 ml of physiologic saline for a consecutive series of 30-min intervals and ADF concentration (absorption) was determined photometrically. The model was verified by three experiments. In experiment 1, the lower limit of quantification (LLoQ, coefficient of variation = 20 % and difference of 5 standard deviations (SD) from blank) of ADF in physiologic saline was determined by measuring the absorption of 15 dilutions of ADF in physiologic saline (containing 0.625 ng to 12.5 μg methylene blue/ml) photometrically for ten times. In experiment 2, long-term linearity of ADF perfusion/outflow was investigated using 11 specimens. The ADF released through the window was collected in the said containers separately for each consecutive interval of 30 min for up to 240 min. Absorption was determined and analysed by linear regression over time. In experiment 3, perfusion before (2×) and after single treatment according to the following three groups was measured: BisGMA-based sealant (Seal&Protect®), an acidic fluoride solution (elmex Fluid®) and control (no treatment). Results In experiment 1, the LLoQ was 0.005 μg methylene blue/ml. In experiment 2, permeability was different within the specimens and decreased highly linearly with time, allowing the prediction of future values. In experiment 3, Seal&Protect® completely occluded Dentinal tubules. elmex Fluid® increased tubular permeability by about 30 % compared to control. Conclusions A model comprising the use of artificial Dentinal Fluid was developed and validated allowing screening of therapeutic agents for the treatment of DH through reliable measurement of permeability of cervical root dentine. Clinical relevance The described in vitro model allows evaluation of potential agents for the treatment of DH at the clinically relevant cervical region of human teeth.
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Development and validation of an in vitro model for measurements of cervical root dentine permeability.
Clinical oral investigations, 2014Co-Authors: Holger Jungbluth, Thomas Attin, Wolfgang BuchallaAbstract:The aim of this series of studies was the development and validation of a new model for evaluation of Dentinal hypersensitivity (DH) therapies. Roots from extracted human teeth were sealed with a flowable composite. In the cervical area, a 3-mm-wide circular window was ground through the seal 1 mm deep into dentine. The pulp lumen was connected to a reservoir of artificial Dentinal Fluid (ADF) containing protein, mineral salts and methylene blue. At increased pulpal pressure, the ADF released through the said window was collected in containers each with 20 ml of physiologic saline for a consecutive series of 30-min intervals and ADF concentration (absorption) was determined photometrically. The model was verified by three experiments. In experiment 1, the lower limit of quantification (LLoQ, coefficient of variation = 20 % and difference of 5 standard deviations (SD) from blank) of ADF in physiologic saline was determined by measuring the absorption of 15 dilutions of ADF in physiologic saline (containing 0.625 ng to 12.5 μg methylene blue/ml) photometrically for ten times. In experiment 2, long-term linearity of ADF perfusion/outflow was investigated using 11 specimens. The ADF released through the window was collected in the said containers separately for each consecutive interval of 30 min for up to 240 min. Absorption was determined and analysed by linear regression over time. In experiment 3, perfusion before (2×) and after single treatment according to the following three groups was measured: BisGMA-based sealant (Seal&Protect®), an acidic fluoride solution (elmex Fluid®) and control (no treatment). In experiment 1, the LLoQ was 0.005 μg methylene blue/ml. In experiment 2, permeability was different within the specimens and decreased highly linearly with time, allowing the prediction of future values. In experiment 3, Seal&Protect® completely occluded Dentinal tubules. elmex Fluid® increased tubular permeability by about 30 % compared to control. A model comprising the use of artificial Dentinal Fluid was developed and validated allowing screening of therapeutic agents for the treatment of DH through reliable measurement of permeability of cervical root dentine. The described in vitro model allows evaluation of potential agents for the treatment of DH at the clinically relevant cervical region of human teeth.