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Saghiri MA, Vakhnovetsky J, Abdolmaleki A, Samadi E, Samadi F, Napoli S, Conte M, Morgano SM. Mechanical properties of simulated dentin caries treated with metal cations and L-ascorbic acid 2-phosphate. Odontology 2024; 112:489-500. [PMID: 37978093 DOI: 10.1007/s10266-023-00868-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 10/16/2023] [Indexed: 11/19/2023]
Abstract
This pH cycling study aimed to investigate the effects of L-Ascorbic acid 2-phosphate (AA2P) salts of Mg, Zn, Mn, Sr, and Ba on the surface microhardness, compressive strength, diametral tensile strength (DTS), and solubility of root canal dentin. 186 cylindrical dentin specimens from 93 teeth were fortified with optimal concentrations of AA2P salts of Mg (0.18 mM), Zn (5.3 µM), Mn (2.2 × 10-8 M), Sr (1.8 µM), and Ba (1.9 µM). Saline was used as the control group. These dentin specimens underwent a 3-day cycling process simulating dentin caries formation through repeated sequences of demineralization and remineralization. Surface microhardness at 100 and 500 µm depths (n = 10/subgroup), scanning electron microscopy (n = 3/group), compressive strength (n = 10/group), DTS (n = 6/group), and solubility (n = 5/group) tests were performed to analyze the dentin specimens. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, and Post Hoc Tukey tests (p < 0.05). The control group had significantly lower microhardness at both depths (p < 0.001), reduced DTS (p = 0.001), decreased compressive strength (p < 0.001), and higher weight loss (p < 0.001) than all other groups. The Sr group had the highest compressive strength and microhardness among all the groups. The microhardness was significantly higher for the 500 µm depth than the 100 µm depth (p < 0.001), but the difference in microhardness between depths across groups was not significant (p = 0.211). All fortifying solutions provided some protection against artificial caries lesions. Therefore, these elements might have penetrated and reinforced the demineralized dentin against acid dissolution.
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Affiliation(s)
- Mohammad Ali Saghiri
- Department of Restorative Dentistry, Rutgers School of Dental Medicine, Newark, NJ, USA.
- Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, CA, USA.
- MSB C639A, Rutgers Biomedical and Health Sciences, 185 South Orange Avenue, Newark, NJ, 07103, USA.
| | - Julia Vakhnovetsky
- Sector of Innovation in Dentistry, Dr. Hajar Afsar Lajevardi Research Cluster (DHAL), Hackensack, NJ, USA
- University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | | | - Elham Samadi
- Sector of Innovation in Dentistry, Dr. Hajar Afsar Lajevardi Research Cluster (DHAL), Hackensack, NJ, USA
- Biomaterials Laboratory, Rutgers School of Dental Medicine, Newark, NJ, USA
| | - Fatereh Samadi
- Sector of Innovation in Dentistry, Dr. Hajar Afsar Lajevardi Research Cluster (DHAL), Hackensack, NJ, USA
- Biomaterials Laboratory, Rutgers School of Dental Medicine, Newark, NJ, USA
| | - Salvatore Napoli
- Department of Oral & Maxillofacial Surgery, Rutgers School of Dental Medicine, Newark, NJ, USA
| | - Michael Conte
- Department of Restorative Dentistry, Office of Clinical Affairs, Rutgers School of Dental Medicine, Newark, NJ, USA
| | - Steven M Morgano
- Department of Restorative Dentistry, Rutgers School of Dental Medicine, Newark, NJ, USA
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Leskovar T, Pajnič IZ. Comparative analysis of DNA preservation in permanent and deciduous teeth of adults and non-adults: Implications for archaeological and forensic research. Forensic Sci Int 2023; 353:111882. [PMID: 37979239 DOI: 10.1016/j.forsciint.2023.111882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 10/30/2023] [Accepted: 11/07/2023] [Indexed: 11/20/2023]
Abstract
This study investigates the preservation of DNA in different categories of teeth, including permanent and deciduous, fully developed and not fully developed, in both adults and non-adults. Teeth were sampled from a modern-era cemetery in Ljubljana, Slovenia. DNA extraction was performed using a full demineralisation protocol. DNA quantity and quality were assessed using qPCR analyses, and autosomal STR typing was conducted to verify genetic profiles. Results revealed significant differences in DNA preservation among various tooth categories. Fully developed permanent teeth of adults exhibited the highest DNA yields, attributed to their fully developed roots and thicker cementum, which is rich in DNA. Deciduous teeth, with thinner enamel and cementum, showed lower DNA preservation regardless of developmental stage. Non-adult teeth generally yielded less DNA compared to adults, even when considering only fully developed permanent teeth, indicating factors beyond developmental stage. These findings suggest that, in archaeological and forensic contexts, researchers should prioritize fully developed permanent teeth for DNA analysis due to their superior preservation. Additionally, this study underscores the importance of considering tooth type and developmental stage when selecting samples for genetic analysis in cases where petrous bone is unavailable, expanding our understanding of DNA preservation in human remains.
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Affiliation(s)
- Tamara Leskovar
- Centre for Interdisciplinary Research in Archaeology, Department of Archaeology, Faculty of Arts, University of Ljubljana, Ljubljana, Slovenia
| | - Irena Zupanič Pajnič
- Institute of Forensic Medicine, Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia.
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Chen Y, Wu R, Shen L, Yang Y, Wang G, Yang B. The multi-scale meso-mechanics model of viscoelastic dentin. J Mech Behav Biomed Mater 2022; 136:105525. [PMID: 36302275 DOI: 10.1016/j.jmbbm.2022.105525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 10/07/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022]
Abstract
Human dentin is a hierarchical material with multi-level micro-/nano-structures, consisting of tubule, perti-tubular dentin (PTD) and intertubular dentin (ITD) as the major constituents at microscale; and the PTD and ITD are further composed of collagen and hydroxyapatite (HAp) crystals with different volume fractions at nanoscale. In most cases, the HAp is considered as elastic while the collagen as viscoelastic material. It is of great significance to study the hierarchical structure and viscoelasticity of human dentin to understand the mechanical properties of dentin for further development of restorative materials. Based on this, this paper focuses on multiscale modeling of the elastic properties and dynamic viscoelastic response of dentin and establishes a bottom-up micromechanics model from nano-to macro-scale. In order to study the nanostructural effect on the viscoelastic behavior of hierarchical structures, the homogenization theories of random platelets composites (HTRPC) and the locally-exact homogenization theory (LEHT) are introduced for the homogenization of heterogeneous materials of microstructures at different levels. The HTRPC, based on Eshelby Inclusion theory, is used to predict the effective modulus of PTD and ITD. The LEHT is a method for homogenizing multiphase dentin characterized by repeated unit cells (RUCs). The resulting predictions are in very good agreement with several experimental data from the literature. In addition, the results of nanostructrual effect on dentin show that the viscoelasticity of dentin is majorly contributed by collagen and the HAp greatly provide the strength and hardness of dentin. Furthermore, the ageing effect on dentin's viscoelasticity is considered from the proposed multiscale micromechanics model. It is demonstrated that the ageing effect is much more influential in affecting the loss moduli of dentin than the storage.
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Affiliation(s)
- Yusen Chen
- Department of Civil Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Rui Wu
- Department of Civil Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Center for Balance Architecture, Zhejiang University, Hangzhou, 310007, China
| | - Lulu Shen
- Department of Civil Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Yabin Yang
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
| | - Guannan Wang
- Department of Civil Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Center for Balance Architecture, Zhejiang University, Hangzhou, 310007, China.
| | - Bo Yang
- Department of Civil Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
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Barreto de Oliveira RD, de Sousa FB, Algarni AA, Eckert GJ, Hara AT. Susceptibility of Dental Enamel of Different Ages to Caries-Like Lesion Development. Caries Res 2020; 54:475-482. [PMID: 33176329 DOI: 10.1159/000509461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 06/10/2020] [Indexed: 11/19/2022] Open
Abstract
This study investigated the impact of estimated age, anatomical location, and the presence of wear facets on the susceptibility of enamel to develop caries-like lesions. Extracted human premolars (n = 261) had their age estimated between 10 and 93 years old, using established forensic methods. Specimens of enamel (4 × 4 mm) were prepared from the middle of the buccal surfaces, preserving the outer surface layer. The central area of the block (4 × 1 mm) was protected with nail polish and used as an internal control. The specimens were demineralized for 8 days (with 0.1 M acetic acid, 1.28 mM Ca, 0.74 mM Pi, and 0.03 µg F/mL, pH 5.0), to simulate caries-like lesion development. They were then scanned individually using microtomography, and digital 2D images were used to calculate the outcomes of integrated mineral concentration loss (ΔZ in µm/g/cm3) and lesion depth (LD in µm) at 3 locations, i.e., the cervical, middle, and occlusal thirds. The presence of natural surface wear facets was considered in the analysis. Data were evaluated using a linear mixed-effects models (α = 0.05). ΔZ increased significantly as a function of estimated tooth age at all 3 locations, and this increase was greater after the age of 30 years (p < 0.001), when a higher ΔZ was found in the occlusal third than in the middle and cervical thirds (p < 0.001). LD increased only in the occlusal third before the age of 30 years (p = 0.039) and this increase was significantly greater after 30 years at all 3 locations (p < 0.01), with no differences among them (p > 0.15). The presence of wear facets significantly increased ΔZ and LD (p < 0.001 for both). Overall, we concluded that the susceptibility of enamel to developing caries-like lesions increased with estimated dental age. This effect was more pronounced after the estimated age of 30 years and in the presence of natural tooth wear facets.
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Affiliation(s)
| | | | - Amnah A Algarni
- Department of Restorative Dentistry, College of Dentistry, Taibah University, Medina, Saudi Arabia
| | - George J Eckert
- Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Anderson T Hara
- Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, Indianapolis, Indiana, USA,
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Montoya C, Arola D, Ossa EA. Deformation behaviour of aged coronal dentin. Gerodontology 2018; 35:95-100. [PMID: 29368792 DOI: 10.1111/ger.12321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE This study aimed to identify the changes in the time-dependent deformation response of coronal dentin with ageing and its relationship with changes in chemical composition. BACKGROUND The structural behaviour of dentin with ageing is affected by changes in the density and diameter of its dentinal tubules (ie porosity), as well as changes in chemical composition throughout the tooth. However, little is known about the time-dependent deformation behaviour of aged dentin and the importance of its hierarchical structure and variations in chemical composition. MATERIALS AND METHODS The spherical indentation response of aged coronal dentin was analysed in the outer, middle and inner regions, and its time-dependent deformation response was modelled in terms of its microstructure and chemical composition using a model recently proposed for young dentin. RESULTS The viscous deformation behaviour of aged dentin followed a power-law response with a decrease in the stress exponent when compared to young dentin. These results can be explained by cross-linking of the collagen present in the tissue. CONCLUSION A decrease in the deformation ability of aged dentin was found. This behaviour could be a result of a dissolution process and reprecipitation of the minerals present in intertubular dentin into the dentinal tubules.
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Affiliation(s)
| | - Dwayne Arola
- Department of Materials Science & Engineering, University of Washington, Seattle, WA, USA.,Departments of Restorative Dentistry and Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA
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Montoya C, Arango-Santander S, Peláez-Vargas A, Arola D, Ossa E. Effect of aging on the microstructure, hardness and chemical composition of dentin. Arch Oral Biol 2015; 60:1811-20. [DOI: 10.1016/j.archoralbio.2015.10.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 06/17/2015] [Accepted: 10/01/2015] [Indexed: 10/23/2022]
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Pinna R, Maioli M, Eramo S, Mura I, Milia E. Carious affected dentine: its behaviour in adhesive bonding. Aust Dent J 2015; 60:276-93. [DOI: 10.1111/adj.12309] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2015] [Indexed: 01/31/2023]
Affiliation(s)
- R Pinna
- Department of Biomedical Science; University of Sassari; Sassari Italy
| | - M Maioli
- Department of Biomedical Science; University of Sassari; Sassari Italy
- National Institute of Biostructures and Biosystems; Italy
| | - S Eramo
- Department of Surgery and Biomedical Science; University of Perugia; Perugia Italy
| | - I Mura
- Department of Biomedical Science; University of Sassari; Sassari Italy
| | - E Milia
- Department of Biomedical Science; University of Sassari; Sassari Italy
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Kantoor P, Srivastava N, Rana V, Adlakha VK. Alterations in the mechanical properties of the extracted human teeth to be used as biological restorations on storing them in different storage media: anin vitrostudy. Dent Traumatol 2015; 31:308-13. [DOI: 10.1111/edt.12158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Pallavi Kantoor
- Department of Paedodontics & Preventive Dentistry; Subharti Dental College; Meerut India
| | - Nikhil Srivastava
- Department of Paedodontics & Preventive Dentistry; Subharti Dental College; Meerut India
| | - Vivek Rana
- Department of Paedodontics & Preventive Dentistry; Subharti Dental College; Meerut India
| | - Vivek K. Adlakha
- Department of Paedodontics & Preventive Dentistry; Subharti Dental College; Meerut India
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Importance of age on the dynamic mechanical behavior of intertubular and peritubular dentin. J Mech Behav Biomed Mater 2014; 42:229-42. [PMID: 25498296 DOI: 10.1016/j.jmbbm.2014.11.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/20/2014] [Accepted: 11/22/2014] [Indexed: 11/23/2022]
Abstract
An experimental evaluation of human coronal dentin was performed using nanoscopic dynamic mechanical analysis (nanoDMA). The primary objectives were to quantify any unique changes in mechanical behavior of intertubular and peritubular dentin with age, and to evaluate the microstructure and mechanical behavior of the mineral deposited within the lumens. Specimens of coronal dentin were evaluated by nanoDMA using single indents and in scanning mode via scanning probe microscopy. Results showed that there were no significant differences in the storage modulus or complex modulus between the two age groups (18-25 versus 54-83 yrs) for either the intertubular or peritubular tissue. However, there were significant differences in the dampening behavior between the young and old dentin, as represented in the loss modulus and tanδ responses. For both the intertubular and peritubular components, the capacity for dampening was significantly lower in the old group. Scanning based nanoDMA showed that the tubules of old dentin exhibit a gradient in elastic behavior, with decrease in elastic modulus from the cuff to the center of tubules filled with newly deposited mineral.
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Xu H, Zheng Q, Shao Y, Song F, Zhang L, Wang Q, Huang D. The effects of ageing on the biomechanical properties of root dentine and fracture. J Dent 2014; 42:305-11. [DOI: 10.1016/j.jdent.2013.11.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/24/2013] [Accepted: 11/29/2013] [Indexed: 11/26/2022] Open
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11
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Liu Y, Yao X, Liu YW, Wang Y. A Fourier transform infrared spectroscopy analysis of carious dentin from transparent zone to normal zone. Caries Res 2014; 48:320-9. [PMID: 24556607 PMCID: PMC4422165 DOI: 10.1159/000356868] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 10/16/2013] [Indexed: 01/22/2023] Open
Abstract
It is well known that caries invasion leads to the differentiation of dentin into zones with altered composition, collagen integrity and mineral identity. However, understanding of these changes from the fundamental perspective of molecular structure has been lacking so far. In light of this, the present work aims to utilize Fourier transform infrared spectroscopy (FTIR) to directly extract molecular information regarding collagen's and hydroxyapatite's structural changes as dentin transitions from the transparent zone (TZ) into the normal zone (NZ). Unembedded ultrathin dentin films were sectioned from carious teeth, and an FTIR imaging system was used to obtain spatially resolved FTIR spectra. According to the mineral-to-matrix ratio image generated from large-area low-spectral-resolution scan, the TZ, the NZ and the intermediate subtransparent zone (STZ) were identified. High-spectral-resolution spectra were taken from each zone and subsequently examined with regard to mineral content, carbonate distribution, collagen denaturation and carbonate substitution patterns. The integrity of collagen's triple helical structure was also evaluated based on spectra collected from demineralized dentin films of selected teeth. The results support the argument that STZ is the real sclerotic layer, and they corroborate the established knowledge that collagen in TZ is hardly altered and therefore should be reserved for reparative purposes. Moreover, the close resemblance between the STZ and the NZ in terms of carbonate content, and that between the STZ and the TZ in terms of being A-type carbonate-rich, suggest that the mineral that initially occludes dentin tubules is hydroxyapatite newly generated from odontoblastic activities, which is then transformed into whitlockite in the demineralization/remineralization process as caries progresses.
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Ivancik J, Majd H, Bajaj D, Romberg E, Arola D. Contributions of aging to the fatigue crack growth resistance of human dentin. Acta Biomater 2012; 8:2737-46. [PMID: 22484693 DOI: 10.1016/j.actbio.2012.03.046] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 03/21/2012] [Accepted: 03/28/2012] [Indexed: 10/28/2022]
Abstract
An evaluation of the fatigue crack resistance of human dentin was conducted to identify the degree of degradation that arises with aging and the dependency on tubule orientation. Fatigue crack growth was achieved in specimens of coronal dentin through application of Mode I cyclic loading and over clinically relevant lengths (0 ≤ a ≤ 2 mm). The study considered two directions of cyclic crack growth in which the crack was either in-plane (0°) or perpendicular (90°) to the dentin tubules. Results showed that regardless of tubule orientation, aging of dentin is accompanied by a significant reduction in the resistance to the initiation of fatigue crack growth, as well as a significant increase in the rate of incremental extension. Perpendicular to the tubules, the fatigue crack exponent increased significantly (from m=14.2 ± 1.5 to 24.1 ± 5.0), suggesting an increase in brittleness of the tissue with age. For cracks extending in-plane with the tubules, the fatigue crack growth exponent does not change significantly with patient age (from m=25.4 ± 3.03 to 22.9 ± 5.3), but there is a significant increase in the incremental crack growth rate. Regardless of age, coronal dentin exhibits the lowest resistance to fatigue crack growth perpendicular to the tubules. While there are changes in the cyclic crack growth rate and mechanisms of cyclic extension with aging, this tissue maintains its anisotropy.
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Singhrao SK, Nicholson K, Crean S. Informed choices for challenging specimens when choosing methacrylate resin systems for histology. Microsc Res Tech 2011; 75:576-85. [DOI: 10.1002/jemt.21094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/23/2011] [Indexed: 11/10/2022]
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Ryou H, Romberg E, Pashley DH, Tay FR, Arola D. Nanoscopic dynamic mechanical properties of intertubular and peritubular dentin. J Mech Behav Biomed Mater 2011; 7:3-16. [PMID: 22340680 DOI: 10.1016/j.jmbbm.2011.08.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 08/11/2011] [Accepted: 08/17/2011] [Indexed: 10/17/2022]
Abstract
An experimental evaluation of intertubular and peritubular dentin was performed using nanoindentation and Dynamic Mechanical Analysis (DMA). The objective of the investigation was to evaluate the differences in dynamic mechanical behavior of these two constituents and to assess whether their response is frequency dependent. Specimens of hydrated coronal dentin were evaluated by DMA using single indents over a range of parametric conditions and using scanning probe microscopy. The complex (E∗), storage (E') and loss moduli (E″) of the intertubular and peritubular dentin were evaluated as a function of the dynamic loading frequency and static load in the fully hydrated condition. The mean complex E∗ (19.6 GPa) and storage E' (19.2 GPa) moduli of the intertubular dentin were significantly lower than those for peritubular dentin (E∗ = 31.1 GPa, p < 0.05; E' = 30.3 GPa, p < 0.05). There was no significant influence of dynamic loading frequency on these measures. Although there was no significant difference in the loss modulus (E″) between the two materials (p > 0.05), both constituents exhibited a significant increase in E″ with dynamic load frequency and reduction in the quasi-static component of indentation load. The largest difference in dynamic behavior of the two tissues was noted at small quasi-static indentation loads and the highest frequency.
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Affiliation(s)
- Heonjune Ryou
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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16
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Castanho GM, Marques MM, Marques JB, Camargo MA, De Cara AA. Micromorphological and hardness analyses of human and bovine sclerotic dentin: a comparative study. Braz Oral Res 2011; 25:274-9. [PMID: 21670860 DOI: 10.1590/s1806-83242011000300014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 02/16/2011] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to test the hypothesis that both human and bovine sclerotic dentin have similar hardness properties, in addition to similar micromorphological characteristics. Sixteen teeth (8 human and 8 bovine) exhibiting exposed dentin in the incisal edge and showing characteristics typical of sclerosis were used. Vickers surface microhardness testing was conducted. Three areas of the dentin surface of each specimen were selected. All teeth were processed for scanning electron microscopy in order to estimate the amount (in percentage) of solid dentin on the sclerotic dentin surface. The data were compared by Student's t test (α = 0.05). The micromorphological and microhardness data were compared by Pearson's linear correlation test (α = 0.05). The mean percentages of solid dentin of human and bovine sclerotic dentin were similar (human 90.71 ± 0.83 and bovine 89.08 ± 0.81, p = 0.18). The mean microhardness value (VHN) of human sclerotic dentin was significantly higher than that of bovine sclerotic dentin (human 45.26 ± 2.92 and bovine 29.93 ± 3.83, p = 0.006). No correlation was found between the microhardness values and the amount of solid dentin in the sclerotic dentin, irrespective of the species considered (human R² = 0.0240, p = 0.714; bovine R² = 0.0017, p = 0.923; and combined R² = 0.038, p = 0.46). We concluded that although both bovine and human sclerotic dentin present a similar amount of solid tissue, human sclerotic dentin presents higher microhardness than bovine sclerotic dentin.
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Affiliation(s)
- Gisela Muassab Castanho
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo, São Paulo, Brazil
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Macedo GV, Yamauchi M, Bedran-Russo AK. Effects of chemical cross-linkers on caries-affected dentin bonding. J Dent Res 2009; 88:1096-100. [PMID: 19892915 DOI: 10.1177/0022034509351001] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The achievement of a strong and stable bond between composite resin and dentin remains a challenge in restorative dentistry. Over the past two decades, dental materials have been substantially improved, with better handling and bonding characteristics. However, little attention has been paid to the contribution of collagen structure/stability to bond strength. We hypothesized that the induction of cross-linking in dentin collagen improves dentin collagen stability and bond strength. This study investigated the effects of glutaraldehyde-and grape seed extract-induced cross-linking on the dentin bond strengths of sound and caries-affected dentin, and on the stability of dentin collagen. Our results demonstrated that the application of chemical cross-linking agents to etched dentin prior to bonding procedures significantly enhanced the dentin bond strengths of caries-affected and sound dentin. Glutaraldehyde and grape seed extract significantly increased dentin collagen stability in sound and caries-affected dentin, likely via distinct mechanisms.
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Affiliation(s)
- G V Macedo
- Department of Operative Dentistry, University of North Carolina at Chapel Hill, NC, USA
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Xiong F, Chao Y, Zhu Z. Translucency of newly extracted maxillary central incisors at nine locations. J Prosthet Dent 2008; 100:11-7. [DOI: 10.1016/s0022-3913(08)60128-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Chikawa H, Inai N, Cho E, Kishikawa R, Otsuki M, Foxton RM, Tagami J. Effect of incremental filling technique on adhesion of light-cured resin composite to cavity floor. Dent Mater J 2007; 25:503-8. [PMID: 17076320 DOI: 10.4012/dmj.25.503] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to evaluate the effect of various incremental filling techniques on adhesion between composite and cavity floor using light-cured resin composite. Black ABS resin and hybrid resin composite were used as mold materials--instead of dentin--for the preparation of cavities, and standardized to 5x5x5 mm. Each cavity was then treated with a bonding system (Clearfil SE bond). Resin composite (Clearfil Photo Core) was placed on the bonding resin using different incremental filling techniques or in bulk and irradiated for a total of 80 seconds using a halogen light unit. Specimens were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. Data were analyzed by two-way ANOVA. The results indicated that an incremental filling technique was more effective in improving adhesion to the cavity floor than a bulk filling technique.
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Affiliation(s)
- Hirokazu Chikawa
- Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
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Yamamoto T, Takeishi S, Momoi Y. Finite Element Stress Analysis of Indirect Restorations Prepared in Cavity Bases. Dent Mater J 2007; 26:274-9. [PMID: 17621945 DOI: 10.4012/dmj.26.274] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The objective of this study was to analyze the distribution of tensile stresses in indirect restorations prepared in several composite cavity bases. Elastic moduli of 20 materials were measured by nanoindentation technique for finite element analysis. Axisymmetric models of posterior onlays were constructed using combinations of two onlay materials and three cavity base materials. Thickness of resin cement was 50 um. A vertical load of 95.5 N was applied on the cusp tip. Maximum stress of 18.1 MPa was found in the model consisting of a ceramic onlay and a flowable resin composite base. It was also found that tensile stress increased as the area of the base having a lower elastic modulus became wider. Base materials having higher elastic moduli were determined to be suitable as cavity base materials for posterior restorations.
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Affiliation(s)
- Takatsugu Yamamoto
- Department of Operative Dentistry, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa 230-8501, Japan.
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