@article{Kishen200612,

title = {Digital moiré interferometric investigations on the deformation gradients of enamel and dentine: An insight into non-carious cervical lesions},

author = {A. Kishen and K. B. C. Tan and A. Asundi},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-28944441429&doi=10.1016%2fj.jdent.2005.02.008&partnerID=40&md5=ba66e6f416985be141305899b97fff8f},

doi = {10.1016/j.jdent.2005.02.008},

issn = {03005712},

year  = {2006},

date = {2006-01-01},

journal = {Journal of Dentistry},

volume = {34},

number = {1},

pages = {12 – 18},

abstract = {Objectives: The objective of this study was to evaluate the biomechanical basis of non-carious cervical lesions by examining the patterns of deformation (strain) in the enamel and dentine. Methods: The digital moiré interferometry is optics based non-destructive, whole-field experimental technique that provides whole-field strain information. Diffraction gratings (with a frequency of 1200 lines/mm) were transferred onto sagittal sections of human teeth, which were subsequently loaded compressively for loads ranging from 10 to 200 N at the incisal edge of the tooth. The acquired digital moiré fringe patterns were used to determine the in-plane deformation pattern in the enamel and the dentine in the direction parallel to the long axis (axial direction) and in the direction perpendicular to the long axis (lateral direction) of the tooth. Results: It is observed that the enamel displayed marked strain gradients in the lateral direction, while the coronal dentine experienced marked strain gradients in the axial directions during compression. With the increase in applied loads, the strains in the enamel increased at the cervical edge (above the cemento-enamel junction) on the facial side, while the strains in the dentine increased below the cemento-enamel junction on the facial side. Conclusion: The enamel and dentine displayed unique in-plane deformation patterns in the axial and the lateral directions of the tooth. These experiments support the hypothesis that occlusal loading will contribute to cervical loss of dental hard tissues. © 2005 Elsevier Ltd. All rights reserved.},

note = {Cited by: 33},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen2006i,

title = {Investigations on the dynamics of water in the macrostructural dentine},

author = {Anil Kishen and Adeela Rafique},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845354286&doi=10.1117%2f1.2360257&partnerID=40&md5=cbc6c24c01daf631b6c3036b5dc28214},

doi = {10.1117/1.2360257},

issn = {15602281},

year  = {2006},

date = {2006-01-01},

journal = {Journal of Biomedical Optics},

volume = {11},

number = {5},

abstract = {The purpose of this study was twofold: (1) to investigate the nature and degree of water loss at 21 °C, 60% relative humidity (dehydration) and at 105°C (desiccation), and to relate these findings with (2) the strains produced in the dentine structure during dehydration and rehydration processes. In stage 1, digital moiré interferometry (DMI) was used to study the strain distribution pattern during dehydration and rehydration at 21 °C. In stage 2, the nature and degree of water loss was determined using gravimetric analysis and nuclear magnetic resonance spectroscopy. DMI showed that dehydration produced strains in the dentine structure after an initial latent period. Gravimetric analysis showed that dentine exhibited an initial rapid water-loss phase followed by a slow and steady water-loss phase. Though the major portion of water loss occurred in the initial 2h of dehydration (rapid water-loss phase), no obvious strains were produced during this period. Rehydration lead to the major reversal of dehydration-induced water loss and strains in dentine. Heating at 105°C resulted in further substantial loss of water from dentine. These experiments highlighted that the free water in the dentine surface, porosities and tubules are lost rapidly and constitute the major water lost when dehydrated at 21 °C. © 2006 Society of Photo-Optical Instrumentation Engineers.},

note = {Cited by: 21; All Open Access, Bronze Open Access},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{George2005867,

title = {The role of environmental changes on monospecies biofilm formation on root canal wall by Enterococcus faecalis},

author = {S. George and A. Kishen and K. P. Song},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-28144449410&doi=10.1097%2f01.don.0000164855.98346.fc&partnerID=40&md5=f0a6f1897fbcf5f87f0977c2f2025ae5},

doi = {10.1097/01.don.0000164855.98346.fc},

issn = {00992399},

year  = {2005},

date = {2005-01-01},

journal = {Journal of Endodontics},

volume = {31},

number = {12},

pages = {867 – 872},

publisher = {Lippincott Williams and Wilkins},

abstract = {Biofilm mode of growth is a strategy in microorganisms to survive harsh growth conditions. Although previous studies have established the ability of Enterococcus faecalis to survive postendodontic environmental conditions, the effect of such conditions on the ultrastructural and physiochemical features of E. faecalis biofilm has received less attention. This study aims to evaluate the effect of different growth conditions on the characteristics of E. faecalis biofilm on root canal, and the penetration of E. faecalis into dentinal tubules. Forty-five intact noncarious human maxillary molars were experimented under nutrient-rich, nutrient-deprived, aerobic, and anaerobic conditions for a period of 21 days. Scanning Electron Microscopy with Energy Dispersive X-ray microanalysis, Laser Confocal Scanning Microscopy and Light microscopic examinations were carried out. The microscopic analysis highlighted a distinct variation in the ultrastructure of the biofilms formed under different experimental conditions. The EDX microanalysis showed a significant increase in the levels of Calcium (Ca) in the biofilm structures formed under anaerobic nutrient-deprived condition (p < 0.001). The depth of bacterial penetration was significantly greater in nutrient-rich condition (p < 0.001). This study demonstrated distinct ultrastructural and physiochemical properties of the biofilms formed and dentinal tubular penetration of E. faecalis under different conditions. Copyright © 2005 by the American Association of Endodontists.},

note = {Cited by: 235},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen2005192,

title = {Experimental investigation on the role of water in the mechanical behavior of structural dentine},

author = {A. Kishen and A. Asundi},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644389876&doi=10.1002%2fjbm.a.30288&partnerID=40&md5=b7aceef8b3a0f20956f187580ac99598},

doi = {10.1002/jbm.a.30288},

issn = {00219304},

year  = {2005},

date = {2005-01-01},

journal = {Journal of Biomedical Materials Research - Part A},

volume = {73},

number = {2},

pages = {192 – 200},

abstract = {Dentine is a porous hydrated composite structure that forms the major bulk of the human tooth. The aim of this study was to investigate the role of free water on the in-plane, mechanical strain response in dentine structure. A digital moiré interferometry was used for this purpose. It was observed from this experiment that structural dentine demonstrated distinct strain gradients in the axial (perpendicular to the dentinal tubules) and lateral (parallel to the dentinal tubules) directions. The hydrated dentine displayed significant increase in strain with stress in the direction perpendicular to the dentinal tubules, and this response was characteristic of a tough material. On the contrary, the dehydrated dentine, which was dehydrated at 24°C, 55% relative humidity for 72 h showed a strain response characteristic of a brittle material. The strains formed in the direction parallel to the dentinal tubules for hydrated dentine were consistent and did not vary much with increase in applied loads. Upon dehydration, the outer dentine experienced higher strains, and the difference between the outer and inner dentine became more conspicuous with increase in loads. This experiment highlights hydration-induced, distinct in-plane strain gradients in the directions perpendicular and parallel to the dentinal tubules in the dentine structure. © 2005 Wiley Periodicals, Inc.},

note = {Cited by: 45},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen2005,

title = {Photomechanical investigations on the stress-strain relationship in dentine macrostructure},

author = {A. Kishen and A. Asundi},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-24144463140&doi=10.1117%2f1.1924688&partnerID=40&md5=c606509736e7f31dc1e1445aa885fbdd},

doi = {10.1117/1.1924688},

issn = {15602281},

year  = {2005},

date = {2005-01-01},

journal = {Journal of Biomedical Optics},

volume = {10},

number = {3},

abstract = {In this study photomechanical experiments were carried, out to examine the relationship between macroscopic mechanical stress and strain gradients within the root dentine structure. Threedimensional digital photoelasticity was used to study the stress distribution patterns in tooth models, while digital moiré interferometry was used to study the strain gradients within the natural teeth. The stress analysis showed a distinct bending stress distribution, along faciolingual plane in the coronal and cervical regions of the tooth. There was a reduction in bending towards the apical third of the tooth model. The strain analysis displayed strain gradients in the axial (along the long axis of the tooth) and lateral (perpendicular to the long axis of the tooth) directions in dentine. There was a conspicuous reduction in strains from the cervical to the apical third of the root dentine. The root dentine displayed uniform distribution of normal strains. Although there was a steep increase in stresses from the inner core region to the outer surface of an isotropic tooth model, there were more uniform strain gradients in the natural dentine structure. It is apparent from these observations that complex organization of material properties facilitated distinct strain gradients in dentine structure during mechanical functions. © 2005 Society of Photo-Optical Instrumentation Engineers.},

note = {Cited by: 18; All Open Access, Bronze Open Access},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen2005597,

title = {Periapical biomechanics and the role of cyclic biting force in apical retrograde fluid movement},

author = {A. Kishen},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-24044440461&doi=10.1111%2fj.1365-2591.2005.00986.x&partnerID=40&md5=635fe82690c70d4fea9c9c350f9285d3},

doi = {10.1111/j.1365-2591.2005.00986.x},

issn = {01432885},

year  = {2005},

date = {2005-01-01},

journal = {International Endodontic Journal},

volume = {38},

number = {9},

pages = {597 – 603},

abstract = {Aim: To investigate the stress distribution pattern in the periapical region caused by biting forces and to study the role of cyclic biting loads on periapical fluid movement. Methodology: In the first part, a digital photoelastic experiment was conducted to study stress distribution in the periapical region. In the second, 20 maxillary central incisors were selected and divided into three main groups: normal intact teeth (group 1), tooth specimens in which the root canal was enlarged and maintained wet (group 2), and tooth specimens in which the root canal was enlarged and maintained dry (group 3). The tooth specimens were placed in a polycarbonate support with a cavity filled with a sponge soaked in methylene blue solution to simulate a periapical defect with exudate. During testing, the specimens were placed in a water bath at 37°C, and were loaded cyclically with a load of 20 N, at a rate of 72 cycles min-1, to a maximum of 20 000 cycles. The specimens were then sectioned and evaluated for retrograde fluid movement using light microscopy. The data were analysed using one-way ANOVA (post hoc tests). Results: Digital photoelastic experiments showed that the compression of teeth produced bending stresses in the periapical region. Testing with cyclic loads demonstrated retrograde fluid movement into the apical portion of the root canal and extraradicular region in all groups. There was a significant difference amongst the apical retrograde fluid movement displayed by different groups (<0.01). Group 2, in which the root canal was enlarged and maintained wet showed maximum retrograde fluid movement, whilst group 3, in which the root canal was enlarged and maintained dry showed the least retrograde fluid movement. Conclusions: Biting forces would cause bending of the periapical bone and cyclic biting forces would contribute to retrograde fluid movement into the root canal space and extraradicular region. © 2005 International Endodontic Journal.},

note = {Cited by: 15; All Open Access, Bronze Open Access},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{SumDr.200594,

title = {What we leave behind in root canals after endodontic treatment: Some issues and concerns},

author = {Chee Peng Sum Dr. and Jennifer Neo and Anil Kishen},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33644860974&doi=10.1111%2fj.1747-4477.2005.tb00312.x&partnerID=40&md5=343630c0472649be8abfca6d3c94022f},

doi = {10.1111/j.1747-4477.2005.tb00312.x},

issn = {17474477},

year  = {2005},

date = {2005-01-01},

journal = {Australian Endodontic Journal},

volume = {31},

number = {3},

pages = {94 – 100},

abstract = {The benefits of using sodium hypochlorite (NaOCI) and ethylenediaminetetraacetic acid (EDTA) as endodontic irrigants, and calcium hydroxide as an inter-appointment medicament, are well known to dentists. Many steps undertaken during endodontic treatment and retreatment are rather mechanical in nature, and less attention is committed to understanding the biological issues underlying endodontic treatment and retreatment. It should be noted that dentine is the fundamental substrate in endodontic treatment, and its properties and characteristics are the key determinant of nearly all disease and post-disease processes in the teeth. In this article the effects and counter-effects of NaOCI and EDTA on root canal dentine, and some other related issues are reviewed. This information will enable clinicians to use the beneficial effects of these chemicals, while necessary steps are considered to reduce their harmful effects on dentine substrate.},

note = {Cited by: 17},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen200490,

title = {Stress-strain response in human dentine: Rethinking fracture predilection in postcore restored teeth},

author = {Anil Kishen and Ganesh V. Kumar and Nah-Nah Chen},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1842782363&doi=10.1111%2fj.1600-4469.2004.00250.x&partnerID=40&md5=0b1adbc5b6dd32ec5064b3a3f1adea75},

doi = {10.1111/j.1600-4469.2004.00250.x},

issn = {16004469},

year  = {2004},

date = {2004-01-01},

journal = {Dental Traumatology},

volume = {20},

number = {2},

pages = {90 – 100},

publisher = {Blackwell Munksgaard},

abstract = {In this study, the biomechanical perspective of fracture predilection in post-core restored teeth is investigated using computational, experimental, and fractographic analyses. The computational finite element analysis and the experimental tensile testing are used to evaluate the stress-strain response in structural dentine. The fractographic evaluations are conducted using laser scanning confocal microscopy and scanning electron microscopy to examine the topography of dentine from experimentally fractured specimens, and clinically fractured post-core restored teeth specimens. These experiments aided in correlating the stress-strain response in structural dentine with cracks and catastrophic fractures in post-core restored teeth. It was observed from these experiments that the inner dentine displayed distinctly high strains (deformations), while the outer dentine demonstrated high stresses during tensile loading. This implies that the energy fed into the material as it is extended will be spread throughout the inner dentine, and there is less possibility of local increase in stress at the outer dentine, which can lead to the failure of dentine structure. During post-endodontic restoration with increase in loss of inner dentine, the fracture resistance factor contributed by the inner dentine is compromised, and this in turn predisposes the tooth to catastrophic fracture. © Blackwell Munksgaard, 2004.},

note = {Cited by: 89},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kishen2004872,

title = {Chairside sensor for rapid monitoring of Enterococcus faecalis activity},

author = {A. Kishen and N. N. Chen and L. Tan and A. Asundi},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-10044224817&doi=10.1097%2f01.DON.0000129038.97791.8A&partnerID=40&md5=2ee598140393b971ac8ba2470ac83cde},

doi = {10.1097/01.DON.0000129038.97791.8A},

issn = {00992399},

year  = {2004},

date = {2004-01-01},

journal = {Journal of Endodontics},

volume = {30},

number = {12},

pages = {872 – 875},

publisher = {Elsevier Inc.},

abstract = {In this study, optical spectroscopy was used to monitor a chromogenic, enzyme-substrate reaction for the rapid identification of Enterococcus faecalis. The detection system, comprising a miniature spectrophotometer and an accompanying data acquisition system, was placed in an incubator. During testing, a 3-ml test sample was placed in a cuvette within the spectrophotometer. This permitted online, real-time, and remote analysis of spectral signature needed to monitor the bacteria. It was observed that the absorption peak intensity increased conspicuously 3.5 h after inoculation and through the entire period of testing. A linear-regression analysis demonstrated a significant correlation between the increase in absorption peak intensity at 610 nm (r = 0.9389) and 653 nm (r = 0.9387) with the formation of colony-forming units. Optical spectroscopy-based sensing systems can pave the way for rapid, nonlaboratory-based approaches to monitor microbial status quantitatively and qualitatively from clinical samples.},

note = {Cited by: 9},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Griggs2003625,

title = {Mechanism of strength increase for a hydrothermal porcelain},

author = {Jason A. Griggs and Anil Kishen and Kim Nga Le},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042128657&doi=10.1016%2fS0109-5641%2803%2900005-8&partnerID=40&md5=ad66750f6b91d393fba4269d92dcd88b},

doi = {10.1016/S0109-5641(03)00005-8},

issn = {01095641},

year  = {2003},

date = {2003-01-01},

journal = {Dental Materials},

volume = {19},

number = {7},

pages = {625 – 631},

abstract = {Objectives. The objectives of this study were to verify the formation of a hydrolyzed surface layer on Duceram LFC, to determine the effects of such a layer on mechanical material properties, and to identify a specific mechanism responsible for any strength increase observed. Methods. Specimens were fabricated from dentin porcelain by a vibration blotting technique and were prepared to have either blunt or sharp surface flaws. Half of the specimens underwent accelerated aging. Specimens were fractured in three-point flexure to measure their strength, and fractographic analysis was used to determine fracture toughness and residual surface stress. Surface hardness and elastic modulus were measured using a microindentation method. Porcelain surface topography was examined using atomic force microscopy, and Fourier transform infrared spectroscopy was used to determine the composition of the surface layer. Results. The aging treatment modified the porcelain surface topography but did not create a layer with increased hydroxyl ion content. Porcelain strength increased upon aging, and the increase was proportional to initial flaw severity. The apparent fracture toughness of sharp flaw specimens increased to match that for specimens containing blunt flaws upon aging. Surface hardness and elastic modulus decreased upon aging. Significance. Previous studies on the strength increase of hydrothermal porcelain were contradictory because a variety of specimen preparation procedures were used. This study resolves the apparent contradiction by determining the effect of specimen preparation on material strength. 2003 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.},

note = {Cited by: 13},

keywords = {},

pubstate = {published},

tppubtype = {article}

}