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Besnard C, Marie A, Sasidharan S, Harper RA, Shelton RM, Landini G, Korsunsky AM. Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review. Dent J (Basel) 2023; 11:98. [PMID: 37185477 PMCID: PMC10137518 DOI: 10.3390/dj11040098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/19/2023] [Accepted: 03/28/2023] [Indexed: 05/17/2023] Open
Abstract
Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical-chemical-structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health.
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Affiliation(s)
- Cyril Besnard
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Ali Marie
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Sisini Sasidharan
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Robert A. Harper
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Richard M. Shelton
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Gabriel Landini
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Alexander M. Korsunsky
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
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Du Q, Li H, Su J, Zhang L, Zhang S, Zhang Q, Ju J, Wang X, Li Y. Ultrastructural Analysis of Er:YAG Lased Bovine Dentin Contaminated by Cariogenic Bacteria. Photobiomodul Photomed Laser Surg 2022; 40:507-515. [PMID: 35867122 DOI: 10.1089/photob.2021.0124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Objective: The purpose of this study is to investigate the crystal structure of bacteria-contaminated bovine dentin after Er:YAG laser irradiation at various energy densities from macroscale, microscale, and nanoscale. Background: Er:YAG laser can change the morphology and chemical components of dentin. Few preliminary researchers investigate the laser effect on crystal in dentin tissue. Methods: Twenty dentin specimens from bovine incisors were cocultured with S. mutans (UA 159) and divided into four groups with diverse Er:YAG laser irradiation energy (0, 6.37, 12.73, 19.11 J/cm2). The ultrastructure of dentin before and after laser irradiation was investigated with nanoanalytical electron microscopy. X-ray diffraction provided the information of lattice parameters in dentin. The morphology of dentin was observed by scanning electron microscopy. High-resolution transmission electron microscope images and selected-area electron diffraction patterns were obtained for characterizing crystal domain size, structure, and microenvironment of dentin. Results: The combination of these methods disclosed that there exist mineralized, demineralized, and remineralized dentin in the bacteria-invaded dentin and can be feasibly recognized using morphological features. Laser treatments influence hydroxyapatite (HAp) crystals in dentin tissue in different ways: needle HAp in mineralized dentin tissue keeps intact with laser irradiation of no higher than 19.11 J/cm2; laser irradiation improves the crystallinity of lamella HAp by domain growth and rearranges its growth orientations. Conclusions: We report an unprecedented presence of remineralization zone consisting of lamella HAp crystals with distinct high-index planes. These findings have broad implications on the role of laser operation in driving biomineralization and shed new insights into a possible relationship between laser irradiation and remineralization.
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Affiliation(s)
- Qing Du
- Stomatology Department, Peking University Third Hospital, Beijing, China
| | - He Li
- Transmission Electron Microscopy Laboratory, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, China.,Department of Functional Materials, School of Materials Science and Engineering, Hebei Provincial Key Laboratory of Traffic Engineering Materials, Shijiazhuang Tiedao University, Shijiazhuang, China
| | - Jie Su
- Transmission Electron Microscopy Laboratory, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Li Zhang
- Transmission Electron Microscopy Laboratory, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Sun Zhang
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Qian Zhang
- Microbiology Laboratory, Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China
| | - Jing Ju
- Transmission Electron Microscopy Laboratory, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Xiao Wang
- Stomatology Department, Peking University Third Hospital, Beijing, China
| | - Yanting Li
- Department of Functional Materials, School of Materials Science and Engineering, Hebei Provincial Key Laboratory of Traffic Engineering Materials, Shijiazhuang Tiedao University, Shijiazhuang, China
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Effect of Nd:YAG laser irradiation and fluoride application in the progression of dentin erosion in vitro. Lasers Med Sci 2015; 30:2273-9. [DOI: 10.1007/s10103-015-1802-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 08/27/2015] [Indexed: 11/27/2022]
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Ramalho KM, Hsu CYS, de Freitas PM, Aranha ACC, Esteves-Oliveira M, Rocha RG, de Paula Eduardo C. Erbium Lasers for the Prevention of Enamel and Dentin Demineralization: A Literature Review. Photomed Laser Surg 2015; 33:301-19. [DOI: 10.1089/pho.2014.3874] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Karen Müller Ramalho
- Department of Stomatology, School of Dentistry of the University of São Paulo (USP) Prof. São Paulo, SP, Brazil
| | - Chin-ying Stephen Hsu
- Department of Dentistry, Faculty of Dentistry, National University of Singapore (NUS), Singapore
| | - Patrícia Moreira de Freitas
- Department of Restorative Dentistry, School of Dentistry of the University of São Paulo (USP), São Paulo, SP, Brazil
| | - Ana Cecília Correa Aranha
- Department of Restorative Dentistry, School of Dentistry of the University of São Paulo (USP), São Paulo, SP, Brazil
| | - Marcella Esteves-Oliveira
- Department of Operative Dentistry, Periodontology and Preventive Dentistry, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Rodney Garcia Rocha
- Department of Stomatology, School of Dentistry of the University of São Paulo (USP) Prof. São Paulo, SP, Brazil
| | - Carlos de Paula Eduardo
- Department of Restorative Dentistry, School of Dentistry of the University of São Paulo (USP), São Paulo, SP, Brazil
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Marimoto AK, Cunha LA, Yui KCK, Huhtala MFRL, Barcellos DC, Prakki A, Gonçalves SEP. Influence of Nd:YAG laser on the bond strength of self-etching and conventional adhesive systems to dental hard tissues. Oper Dent 2013; 38:447-55. [PMID: 23215546 DOI: 10.2341/11-383-l] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE The aim of this study was to investigate the influence of Nd:YAG laser on the shear bond strength to enamel and dentin of total and self-etch adhesives when the laser was applied over the adhesives, before they were photopolymerized, in an attempt to create a new bonding layer by dentin-adhesive melting. MATERIAL AND METHODS One-hundred twenty bovine incisors were ground to obtain flat surfaces. Specimens were divided into two substrate groups (n=60): substrate E (enamel) and substrate D (dentin). Each substrate group was subdivided into four groups (n=15), according to the surface treatment accomplished: X (Xeno III self-etching adhesive, control), XL (Xeno III + laser Nd:YAG irradiation at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental), S (acid etching + Single Bond conventional adhesive, Control), and SL (acid etching + Single Bond + laser Nd:YAG at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental). The bonding area was delimited with 3-mm-diameter adhesive tape for the bonding procedures. Cylinders of composite were fabricated on the bonding area using a Teflon matrix. The teeth were stored in water at 37°C/48 h and submitted to shear testing at a crosshead speed of 0.5 mm/min in a universal testing machine. Results were analyzed with three-way analysis of variance (ANOVA; substrate, adhesive, and treatment) and Tukey tests (α=0.05). ANOVA revealed significant differences for the substrate, adhesive system, and type of treatment: lased or unlased (p<0.05). The mean shear bond strength values (MPa) for the enamel groups were X=20.2 ± 5.61, XL=23.6 ± 4.92, S=20.8 ± 4.55, SL=22.1 ± 5.14 and for the dentin groups were X=14.1 ± 7.51, XL=22.2 ± 6.45, S=11.2 ± 5.77, SL=15.9 ± 3.61. For dentin, Xeno III self-etch adhesive showed significantly higher shear bond strength compared with Single Bond total-etch adhesive; Nd:YAG laser irradiation showed significantly higher shear bond strength compared with control (unlased). CONCLUSION Nd:YAG laser application prior to photopolymerization of adhesive systems significantly increased the bond strength to dentin.
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Affiliation(s)
- A K Marimoto
- Department of Restorative Dentistry, São José dos Campos School of Dentistry, UNESP- Univ Estadual Paulista, São Paulo, Brazil
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Effect of dental surface treatment with Nd:YAG and Er:YAG lasers on bond strength of resin composite to recently bleached enamel. Lasers Med Sci 2011; 27:755-60. [DOI: 10.1007/s10103-011-0946-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 06/08/2011] [Indexed: 10/17/2022]
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Botta SB, Ana PA, de Sa Teixeira F, da Silveira Salvadori MCB, Matos AB. Relationship Between Surface Topography and Energy Density Distribution of Er,Cr:YSGG Beam on Irradiated Dentin: An Atomic Force Microscopy Study. Photomed Laser Surg 2011; 29:261-9. [PMID: 21219230 DOI: 10.1089/pho.2010.2812] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Sergio Brossi Botta
- Operative Dentistry Department, School of Dentistry, University of Sao Paulo, SP, Brazil
| | - Patricia Aparecida Ana
- Center for Lasers and Applications, Energetic and Nuclear Research Institute, Sao Paulo, SP, Brazil
| | | | | | - Adriana Bona Matos
- Operative Dentistry Department, School of Dentistry, University of Sao Paulo, SP, Brazil
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Ghiggi PC, Dall Agnol RJC, Burnett Júnior LH, Borges GA, Spohr AM. Effect of the Nd:YAG and the Er:YAG Laser on the Adhesive–Dentin Interface: A Scanning Electron Microscopy Study. Photomed Laser Surg 2010; 28:195-200. [PMID: 19795996 DOI: 10.1089/pho.2009.2530] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | | | | | - Ana Maria Spohr
- Pontificial Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
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Arisu HD, Sadik B, Bala O, Türköz E. Computer-assisted evaluation of microleakage after apical resection with laser and conventional techniques. Lasers Med Sci 2007; 23:415-20. [PMID: 17891550 DOI: 10.1007/s10103-007-0497-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Accepted: 08/31/2007] [Indexed: 10/22/2022]
Abstract
The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces after apicoectomy with conventional techniques and laser beam. Sixty single-rooted extracted teeth were selected for the study. The crowns were resected below the cemento-enamel junction. Then, these teeth were treated endodontically and filled with gutta-percha using AH-26 root canal sealer. The teeth were randomly divided into four groups of 15 teeth in each. The roots were resected perpendicular to its long axis 3 mm from the apex using Er: yttrium-aluminium-garnet (YAG) laser irradiation in groups 1 and 2, and the resected root surfaces were lased with Nd:YAG laser in group 2. The apexes were resected by a high-speed handpiece in groups 3 and 4, and the resected root surfaces were lased with Nd:YAG laser in group 4. Ten teeth in each group were used for leakage studies, and the other five teeth were used for scanning electron microscopic examinations. Seven sections were obtained from each root to assess the microleakage, and the sections were analyzed in a computer-assisted manner. No statistically significant differences were observed between the leakage percentage of groups 1 and 3 and groups 2 and 4 (p>0.05). Morphological differences were observed between apical dentin surfaces resected with conventional techniques and laser beam.
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Affiliation(s)
- Hacer Deniz Arisu
- Faculty of Dentistry, Department of Operative Dentistry and Endodontics, Gazi University, 8. Cad 82. Sok Emek, 06510 Ankara, Turkey.
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Rolla JN, Mota EG, Oshima HMS, Júnior LHB, Spohr AM. Nd:YAG laser influence on microtensile bond strength of different adhesive systems for human dentin. Photomed Laser Surg 2007; 24:730-4. [PMID: 17199473 DOI: 10.1089/pho.2006.24.730] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVE The purpose of this study was to investigate the influence of Nd:YAG on microtensile bond strength (microTBS) of different adhesive systems for human dentin. BACKGROUND DATA Lasers have been widely used in dentistry. New adhesive systems with different chemical compositions are introduced every year, and it is important to investigate the bonding of new adhesive systems to dentin irradiated with laser. METHODS The occlusal surfaces of third molars were removed to obtain flat dentin surfaces. The teeth were randomly divided into six groups. Each adhesive system was applied, according to manufacturers' instructions, to surface dentine with and without Nd:YAG laser irradiation (0.9 W, 15 Hz, 60 mJ per pulse). A block of composite resin was built over the adhesive layer. The specimens were sectioned to obtain 0.70 x 0.70 mm of transversal section. Twenty test specimens were selected for each group, and were then submitted to microTBS on a universal testing machine. RESULTS According to Student's t-test, for Single Bond, there was no statistically significant difference without (49.32 MPa) and with (47.34 MPa) laser application (p = 0.60). For the Tyrian SPE/One Step Plus, microTBS value with laser (27.09 MPa) was statistically higher than without laser (19.13 MPa), as well as for Adper Prompt L-Pop (22.85 and 13.78 Mpa; p < or = 0.01). CONCLUSION The application of Nd:YAG laser to dentin provided an increase in the bond strength values for the Tyrian SPE/One Step Plus and Adper Prompt L-Pop adhesive systems, but did not influence the bond strength values of the Single Bond adhesive system.
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Affiliation(s)
- Juliana Nunes Rolla
- Department of Dentistry, Pontificial Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
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Mine A, Yoshida Y, Suzuki K, Nakayama Y, Yatani H, Kuboki T. Spectroscopic characterization of enamel surfaces irradiated with Er:YAG laser. Dent Mater J 2006; 25:214-8. [PMID: 16916220 DOI: 10.4012/dmj.25.214] [Citation(s) in RCA: 9] [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 purpose of this study was to investigate the effect of laser irradiation on the enamel surface spectroscopically. Polished bovine enamel surface was irradiated with an Er:YAG laser apparatus and chemically analyzed using X-ray photoelectron spectroscopy (XPS). XPS detected core electron peaks such as carbon (C 1s) and nitrogen (N 1s), as well as calcium (Ca 2s, Ca 2p, Ca 3s, Ca 3p), phosphorous (P 2s, P 2p), and oxygen (O 1s), from the control enamel surface. After irradiation, XPS revealed that the intensity of C 1s peak slightly decreased while that of N 1s diminished below the detection limit. Detailed C 1s narrow scan spectrum of the Er:YAG laser-irradiated enamel surface showed that C-O/C-N, C = O/-CON=, -COO-, and CO,3(2-) components, attributed to the specific composition of enamel and any common carbon contamination in surplus, relatively decreased. The binding energies of Ca 2p and P 2p, delta (Ca 2p, P 2p), and the Ca/P ratio of lased enamel were found to be different from those of non-lased enamel. It was also shown that Er:YAG laser ablation caused surface alterations to the apatitic inorganic components of tooth tissue.
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Affiliation(s)
- Atsushi Mine
- Department of Oral and Maxillofacial Rehabilitation, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, 2-5-1 Shikata-cho, Okayama 700-8525, Japan
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Franke M, Taylor AW, Lago A, Fredel MC. Influence of Nd:YAG laser irradiation on an adhesive restorative procedure. Oper Dent 2006; 31:604-9. [PMID: 17024950 DOI: 10.2341/05-110] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Hard tissue modification by means of laser irradiation is becoming popular in dentistry, since it promotes assorted responses between the tooth and the restorative material. Some studies on the bond strength of adhesive systems to Nd:YAG irradiated teeth have shown distinctive behaviors when irradiation was applied before or after the adhesive agent. This study evaluated the microtensile bond strength of a commercial adhesive system to dentin irradiated with Nd:YAG laser after adhesive application but prior to polymerization. The experiment was conducted in vitro, using freshly extracted human teeth as samples. For the microtensile test, the teeth were separated into 4 different groups according to the energy density of laser irradiation: 0, 5, 10 and 50 J/cm2. The data was analyzed with analysis of variance (ANOVA) and LSD tests, and the results indicated that the group that was irradiated with 5 J/cm2 had significantly higher bond strength values. Adhesive penetration on the etched dentin was observed by scanning electron microscopy, where the images showed better adhesive penetration on dentinal tubules after dentin irradiation with 5 J/cm2. Based on the results of this study, it is possible to conclude that irradiation of dentin with the Nd:YAG laser at low energy densities after application of the adhesive but prior to polymerization might be positive for the adhesive restorative process.
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Affiliation(s)
- Margarete Franke
- Graduation Program in Materials Science and Engineering (PGMAT), Department of Mechanical Engineering, Federal University of Santa Catarina, Santa Catarina, Brazil.
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Brucoli HCP, Arita ES, Eduardo CP. In vitro radiographic analysis of Nd:YAG-laser-irradiated dentin. Lasers Med Sci 2005; 20:89-94. [PMID: 16047086 DOI: 10.1007/s10103-005-0344-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Accepted: 04/28/2005] [Indexed: 10/25/2022]
Abstract
The aim of this study was to evaluate the effects of Nd:YAG laser irradiation on the dentin radiographic image. Previous studies have shown that Nd:YAG laser irradiation is capable of promoting morphological and chemical changes of the dentin surface, indicating the possibility of an alteration of its radiographic image. Dentin of 2-mm-thick mid-coronal sections from 68 extracted posterior teeth was irradiated for 30 s by a Nd:YAG laser (lambda=1,064 nm) on one half of its surface area. The other half was left as a control. The irradiation parameters were: 80 mJ/pulse, 0.8 W, 10 Hz, with a 320-mum flexible quartz optic fiber in contact mode. The 68 samples were radiographed with a 70-kV X-ray setup. The focus-film distance was established as 30 cm and there was no distance between the object and the film. The X-ray exposure time was set as 0.16 s and the radiographic film used was an F-speed dental film. The obtained radiographic images were submitted to a densitometric analysis. The images analyzed showed that there were statistically significant differences between the density of the irradiated dentin images and the non-irradiated dentin images. The image density data showed that the irradiated dentin radiographic images were 6.36% more radiopaque than the non-irradiated dentin images. The Nd:YAG laser irradiation of dentin is able to alter its radiographic image, producing more radiopaque images of the irradiated dentin.
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Affiliation(s)
- H C P Brucoli
- Department of Restorative Dentistry, School of Dentistry, São Paulo University, Av. Prof. Lineu Prestes 2227, CEP, 05508-900, São Paulo, Brazil
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Ribeiro CF, Anido AA, Rauscher FC, Yui KCK, Gonçalves SEDP. Marginal Leakage in Class V Cavities Pretreated with Different Laser Energy Densities. Photomed Laser Surg 2005; 23:313-6. [PMID: 15954821 DOI: 10.1089/pho.2005.23.313] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The purpose of the present study was to evaluate in vitro the degree of marginal leakage in Class V cavities involving the cementoenamel junction. Cavities were 4 mm wide and 2 mm deep. The specimens received dentin pretreatment (37% phosphoric acid) followed by the Single Bond (3M) adhesive system application. The 40 specimens were then divided into four groups: Group 1 (control); Group 2 (Nd:YAG laser at 120 mJ/pulse, frequency of 10 Hz, power of 1.2 W); Group 3 (Nd:YAG laser at 140 mJ/pulse, frequency of 10 Hz, power of 1.4 W); Group 4 (Nd:YAG laser at 160 mJ/pulse, frequency of 10 Hz, power of 1.6 W). The cavities were restored with Z100 composite resin (3M) and light cured at 300-600 mW/cm2 light intensity. Specimens were thermocycled to 500 cycles from 2-50 degrees C. After that, they were dried and sealed with nail varnish, respecting 1 mm around the restorations, and immersed in 0.5% methylene blue solution for 4 h. After this period, the teeth were rinsed, dried, sectioned, and analyzed in a stereoscopic loupe. The highest leakage scores were considered for each specimen. The results were statistically analyzed by the analysis of variance (ANOVA) - Kruskal-Wallis test to the 5% level. For both the enamel and cementum, there was a decrease in marginal leakage with the application of laser energy; no significant differences were observed for Groups 2, 3, and 4. The results also showed a smaller tendency to marginal leakage on the cementum than on the enamel.
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Affiliation(s)
- Carolina Ferraz Ribeiro
- Department of Restorative Dentistry, School of Dentistry, São Paulo State University (UNESP), São José dos Campos, Brazil.
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Bachmann L, Craievich AF, Zezell DM. Crystalline structure of dental enamel after Ho:YLF laser irradiation. Arch Oral Biol 2004; 49:923-9. [PMID: 15353249 DOI: 10.1016/j.archoralbio.2004.05.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2004] [Indexed: 10/26/2022]
Abstract
Irradiation of teeth with lasers using specific wavelengths and energy densities produces surface melting. This effect has been already applied to different procedures such as caries prevention and hypersensitivity reduction. The aim of this study is to characterize the crystalline structure of bovine enamel after holmium laser irradiation. A holmium laser (Ho:YLF) with emission wavelength of 2065 nm was used. Enamel tissues were irradiated in ablative regime and their structures before and after irradiation were analyzed using the powder X-ray diffraction technique. The X-ray diffraction patterns of non-irradiated enamel correspond to carbonated hydroxyapatite and those produced by irradiated samples indicate the existence of a mixture of two crystalline phases: hydroxyapatite and tetracalcium phosphate. The structural characteristics of holmium irradiated enamel were compared with those of the same tissue irradiated with other lasers.
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Affiliation(s)
- Luciano Bachmann
- Centro de Lasers e Aplicações-CLA, Instituto de Pesquisas Energéticas e Nucleares-IPEN, Av. Lineu Prestes, 2242 Cidade Universitária, 05508-900 São Paulo-SP, Brazil.
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Fried D, Zuerlein MJ, Le CQ, Featherstone JDB. Thermal and chemical modification of dentin by 9-11-microm CO2 laser pulses of 5-100-micros duration. Lasers Surg Med 2003; 31:275-82. [PMID: 12355574 DOI: 10.1002/lsm.10100] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVES Previous studies have shown that dentin can be thermally modified by pulsed CO(2) laser irradiation to form a more highly mineralized tissue. The implications are important for the potential laser modification or removal of dentinal and root caries and the transformation of dentin to a more acid resistant mineralized tissue. STUDY DESIGN/MATERIALS AND METHODS Time resolved radiometry measurements with TEA CO(2) laser pulses were used to determine the magnitude of the absorption coefficients of dentin at the highly absorbed CO(2) laser wavelengths and to measure the temperature excursions during lambda = 9.3, 9.6, 10.3, and 10.6 microm laser irradiation at irradiation intensities of 0.1-8 J/cm(2) per pulse. In addition, photoacoustic and transient reflectance measurements were used to monitor the loss of water and organics and to detect the thresholds for surface modification and tissue ablation. RESULTS The absorption coefficients were measured to be 5,000; 6,500; 1,200; and 800 cm(-1) at lambda = 9.3, 9.6, 10.3, and 10.6 microm, respectively. The surface temperatures of dentin were markedly higher than those measured on enamel for similar irradiation intensities due to the lower reflectance losses of dentin and the lower thermal diffusivity of dentin at the respective wavelengths. Hence, lower fluences are required for the thermal decomposition of dentin. Ablation typically occurred with the first few laser-pulses during multiple pulse irradiation and eventually ceased after modification of dentin to a more highly mineralized enamel-like tissue. The debris ejected during the initial laser pulses shielded the surface by as much as 60% at the low fluences employed in this study. Optical and electron microscopy and IR spectroscopy indicated that incident laser pulses with incident fluence as low as 0.5 J/cm(2) at 9.3 and 9.6 microm wavelengths with a duration of 5-8-micros were sufficient to induce chemical and morphological changes in dentin. CONCLUSIONS In this study, the laser parameters for the efficient thermal modification of dentin with minimum heat deposition at CO(2) laser wavelengths were firmly established.
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Affiliation(s)
- Daniel Fried
- Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California 94143, USA.
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De Munck J, Van Meerbeek B, Yudhira R, Lambrechts P, Vanherle G. Micro-tensile bond strength of two adhesives to Erbium:YAG-lased vs. bur-cut enamel and dentin. Eur J Oral Sci 2002; 110:322-9. [PMID: 12206595 DOI: 10.1034/j.1600-0722.2002.21281.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The purpose of the study was to assess the hypotheses that laser irradiation is equally effective for bonding as traditional acid-etch procedures, and that tooth substrate prepared either by Erbium:YAG laser or diamond bur is equally receptive to adhesive procedures. Buccal/oral enamel and mid-coronal dentin were laser-irradiated using an Erbium:YAG laser. A total-etch adhesive (OptiBond FL) applied with and without prior acid-etching and a self-etch adhesive (Clearfil SE Bond) were employed to bond the composite. The micro-tensile bond strength (microTBS) was determined after 24 h of storage in water. Failure patterns were analysed using a stereo-microscope, and samples were processed for Field-emission Scanning Electron Microscopy (Fe-SEM) evaluation. Unbonded, lased enamel and dentin surfaces were evaluated using Fe-SEM as well. The total-etch adhesive bonded significantly less effectively to lased than to bur-cut enamel/dentin. Laser 'conditioning' was clearly less effective than acid-etching. Moreover, acid etching lased enamel and dentin significantly improved the microTBS of OptiBond FL. The self-etch adhesive performed equally to lased as to bur-cut enamel, but significantly less effectively to lased than to bur-cut dentin. It is concluded that cavities prepared by laser appear less receptive to adhesive procedures than conventional bur-cut cavities.
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Affiliation(s)
- Jan De Munck
- Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Belgium
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18
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Habelitz S, Balooch M, Marshall SJ, Balooch G, Marshall GW. In situ atomic force microscopy of partially demineralized human dentin collagen fibrils. J Struct Biol 2002; 138:227-36. [PMID: 12217661 DOI: 10.1016/s1047-8477(02)00029-1] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Dentin collagen fibrils were studied in situ by atomic force microscopy (AFM). New data on size distribution and the axial repeat distance of hydrated and dehydrated collagen type I fibrils are presented. Polished dentin disks from third molars were partially demineralized with citric acid, leaving proteins and the collagen matrix. At this stage collagen fibrils were not resolved by AFM, but after exposure to NaOCl(aq) for 100-240 s, and presumably due to the removal of noncollagenous proteins, individual collagen fibrils and the fibril network of dentin connected to the mineralized substrate were revealed. High-aspect-ratio silicon tips in tapping mode were used to image the soft fibril network. Hydrated fibrils showed three distinct groups of diameters: 100, 91, and 83 nm and a narrow distribution of the axial repeat distance at 67 nm. Dehydration resulted in a broad distribution of the fibril diameters between 75 and 105 nm and a division of the axial repeat distance into three groups at 67, 62, and 57 nm. Subfibrillar features (4 nm) were observed on hydrated and dehydrated fibrils. The gap depth between the thick and thin repeating segments of the fibrils varied from 3 to 7 nm. Phase mode revealed mineral particles on the transition from the gap to the overlap zone of the fibrils. This method appears to be a powerful tool for the analysis of fibrillar collagen structures in calcified tissues and may aid in understanding the differences in collagen affected by chemical treatments or by diseases.
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Affiliation(s)
- Stefan Habelitz
- Department of Preventive and Restorative Dental Sciences, University of California, 707 Parnassus Avenue D-2260, San Francisco, CA 94143, USA.
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19
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Lin CP, Lee BS, Lin FH, Kok SH, Lan WH. Phase, compositional, and morphological changes of human dentin after Nd:YAG laser treatment. J Endod 2001; 27:389-93. [PMID: 11487131 DOI: 10.1097/00004770-200106000-00004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Although techniques for repairing root fracture have been proposed, the prognosis is generally poor. If the fusion of a root fracture by laser is possible, it will offer an alternative to extraction. Our group has attempted to use lasers to fuse a low melting-point bioactive glass to fractured dentin. This report is focused on the phase, compositional, and morphological changes observed by means of X-ray diffractometer, Fourier transforming infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy in human dentin after exposure to Nd:YAG laser. The irradiation energies were from 150 mJ/ pulse-10 pps-4 s to 150 mJ/pulse-30 pps-4 s. After exposure to Nd:YAG laser, dentin showed four peaks on the X-ray diffractometer that corresponding to a-tricalcium phosphate (TCP) and beta-TCP at 20 = 30.78 degrees/34.21 degrees and 32.47 degrees/33.05 degrees, respectively. The peaks of a-TCP and beta-TCP gradually increased in intensity with the elevation of irradiation energy. In Fourier transforming infrared analysis, two absorption bands at 2200 cm(-1) and 2015 cm(-1) could be traced on dentin treated by Nd:YAG laser with the irradiation energies beyond 150 mJ/pulse-10 pps-4 s. The energy dispersive X-ray results showed that the calcium/phosphorus ratios of the irradiated area proportionally increased with the elevation of irradiation energy. The laser energies of 150 mJ/ pulse-30 pps-4 s and 150 mJ/pulse-20 pps-4 s could result in the a-TCP formation and collagen breakdown. However, the formation of glass-like melted substances without a-TCP at the irradiated site was induced by the energy output of 150 mJ/ pulse-10 pps-4 s. Scanning electron micrographs also revealed that the laser energy of 150 mJ/ pulse-10 pps-4 s was sufficient to prompt melting and recrystallization of dentin crystals without cracking. Therefore, we suggest that the irradiation energy of Nd:YAG laser used to fuse a low melting-point bioactive glass to dentin is 150 mJ/ pulse-10 pps-4 s.
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Affiliation(s)
- C P Lin
- Department of Endodontics, School of Dentistry, National Taiwan University, Taipei, Republic of China
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20
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Rohanizadeh R, LeGeros RZ, Fan D, Jean A, Daculsi G. Ultrastructural properties of laser-irradiated and heat-treated dentin. J Dent Res 1999; 78:1829-35. [PMID: 10598913 DOI: 10.1177/00220345990780121001] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted beta-tricalcium phosphate, beta-TCMP, beta-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950 degrees C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.
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Affiliation(s)
- R Rohanizadeh
- Laboratoire de recherche sur les tissus calcifiés et les biomatériaux, Faculté de Chirurgie Dentaire, Nantes, France
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DE PAIVA GONÇALVES SÉRGIOEDUARDO, DE ARAUJO MARIAAMÉLIAMÁXIMO, DAMIÃO ÁLVAROJOSÉ. Dentin Bond Strength: Influence of Laser Irradiation, Acid Etching, and Hypermineralization. ACTA ACUST UNITED AC 1999. [DOI: 10.1089/clm.1999.17.77] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gelskey SC, White JM, Gelskey DE, Kremers W. Vapor emissions resulting from Nd:YAG laser interaction with tooth structure. Dent Mater 1998; 14:453-7. [PMID: 10483409 DOI: 10.1016/s0300-5712(99)00021-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNLABELLED The Neodymium:yttrium aluminum garnet (Nd:YAG) dental laser has been cleared by the United States Food and Drug Administration (FDA) for marketing in intraoral soft tissue treatment. The efficacy and safety of the Nd:YAG laser in the treatment of hard dental tissue as well as the effects of dental irradiation on the pulp and periodontium have been investigated. Odors resulting from laser irradiation have been reported, but the nature and toxicity of associated decomposition vapors is unknown and the health consequences of their inhalation have not yet been studied. OBJECTIVES The purpose of this in vitro study was to identify vapors emitted during interaction of the Nd:YAG laser with carious human enamel and dentin and sound enamel and dentin coated with organic ink. METHODS Vapor emissions were collected from prepared sections of extracted human teeth receiving laser irradiation of 100 mJ and 10 Hz for a duration of 1, 10, or 60 s. Emissions were collected by means of charcoal absorption tubes, and subsequently analyzed using a Gas Chromatograph equipped with Mass Selective (GC/MS) and Flame Ionization Detectors to identify the chemical constituents of the vapors. RESULTS No compounds were identified in Nd:YAG laser-treated caries, enamel and dentin. No volatile vapors were identified from samples of tooth materials exposed to the laser for 1 or 10 s. Camphor was positively identified in the test sample which consisted of India ink-coated dentin and the reference sample of India ink-coated glass beads, both exposed to the laser for 60 s. 2,5-norbornadiene was tentatively identified in these samples. The Threshold Limit Value (TLV) of camphor is 2 ppm with a Lethal Dose Level (LDLo) of 50 mg/kg (human oral), while the TLV and LDLo of 2,5-norbornadiene is unknown. SIGNIFICANCE Occupational and public health safety measures are discussed in this article. Further research is needed to quantify the compounds produced and to determine their toxicity to patients and to dental care providers.
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Affiliation(s)
- S C Gelskey
- Department of Dental Diagnostic and Surgical Sciences, Faculty of Dentistry, University of Manitoba, Winnipeg, Canada.
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Friedman S, Komorowski R, Maillet W, Nguyen HQ, Torneck CD. Susceptibility of Nd:YAG laser-irradiated root surfaces in replanted teeth to external inflammatory resorption. ENDODONTICS & DENTAL TRAUMATOLOGY 1998; 14:225-31. [PMID: 9855802 DOI: 10.1111/j.1600-9657.1998.tb00844.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nd:YAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2 x 3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n = 12 roots) and 3 (n = 4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 pps, 300 microns tip, 20 s). In Groups 2 (n = 12) and 4 (n = 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfusion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 microns) at 180-microns intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P < 0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in Nd:YAG laser-irradiated dentin. Therefore, the clinical application of Nd:YAG laser to the root surfaces of replanted teeth is not warranted.
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Affiliation(s)
- S Friedman
- Department of Endodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada
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Abstract
PURPOSE We test the hypothesis that holmium:YAG lithotripsy efficiency varies with optical fiber size and energy settings (energy density). MATERIALS AND METHODS The 272, 365, 550 and 940 microm. optical fibers delivered 1 kJ. total holmium:YAG energy to calcium oxalate monohydrate calculi at energy output/pulse of 0.2 to 1.5 J. Stone mass loss was measured for each fiber energy setting. Stone crater width was characterized for single energy pulses. Fiber energy outputs were compared before and after lithotripsy. RESULTS Stone mass loss correlated inversely with optical fiber diameter (p <0.05). Stone loss correlated with energy/pulse for the 365, 550 and 940 microm. fibers (p <0.001). The 272 and 365 microm. fibers yielded equivalent stone loss at 0.2 and 0.5 J. per pulse. At energies of 1.0 J. per pulse or greater the 272 microm. optical fiber was prone to damage, and yielded reduced energy output and stone loss compared to the 365 microm. fiber (p <0.01). Stone crater width for single pulse energies correlated with energy settings for all fibers (p <0.001). CONCLUSIONS Lithotripsy efficiency with the holmium:YAG laser depends on pulse energy output and diameter of the optical delivery fiber, implying that lithotripsy efficiency correlates with energy density. The 365 microm. fiber is indicated for most lithotripsy applications. The 272 microm. fiber is susceptible to damage and inefficient energy transmission at energies of 1.0 J. per pulse or greater. The 272 microm. fiber is indicated at energies of less than 1.0 J. per pulse for small caliber ureteroscopes or when maximal flexible ureteroscope deflection is required.
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Affiliation(s)
- G J Vassar
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, USA
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Goodis HE, White JM, Marshall GW, Yee K, Fuller N, Gee L, Marshall SJ. Effects of Nd: and Ho:yttrium-aluminium-garnet lasers on human dentine fluid flow and dental pulp-chamber temperature in vitro. Arch Oral Biol 1997; 42:845-54. [PMID: 9460538 DOI: 10.1016/s0003-9969(97)00076-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dentine specimens were prepared from freshly extracted third molars and initial permeability measured. Each specimen was subjected to Nd:yttrium-aluminium-garnet (YAG) (1.06 or 1.32 microns wavelength) or Ho:YAG (2.10 microns wavelength) laser energy while temperatures in the pulp chambers were recorded. Permeability was again measured and the surfaces examined by scanning electron microscopy. Six crown segments were used for each laser variable and eight permeability measurements were taken before and eight after laser exposure, while temperature was recorded during treatment. All wavelengths reduced permeability but temperature rises were high enough to have caused pulpal damage, indicating that shorter treatment times and lower power settings may be necessary if used in vivo.
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Affiliation(s)
- H E Goodis
- Division of Endodontics, University of California School of Dentistry, San Francisco 94143, USA
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Bonse U, Busch F. X-ray computed microtomography (microCT) using synchrotron radiation (SR). PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1996; 65:133-69. [PMID: 9029944 DOI: 10.1016/s0079-6107(96)00011-9] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- U Bonse
- Institute of Physics, University of Dortmund, Germany
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