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Woodfield PL, Rode AV, Dao D, Dau VT, Madden S, Walsh LJ, Spallek H, Walsh L, Sutton AJ, Zuaiter O, Habeb A, Hirst TR, Rapp L. Optical penetration models for practical prediction of femtosecond laser ablation of dental hard tissue. Lasers Surg Med 2024; 56:371-381. [PMID: 38563442 DOI: 10.1002/lsm.23784] [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: 10/27/2023] [Revised: 01/30/2024] [Accepted: 03/20/2024] [Indexed: 04/04/2024]
Abstract
OBJECTIVES To develop and practically test high-precision femtosecond laser ablation models for dental hard tissue that are useful for detailed planning of automated laser dental restorative treatment. METHODS Analytical models are proposed, derived, and demonstrated for practical calculation of ablation rates, ablation efficiency and ablated morphology of human dental enamel and dentin using femtosecond lasers. The models assume an effective optical attenuation coefficient for the irradiated material. To achieve ablation, it is necessary for the local energy density of the attenuated pulse in the hard tissue to surpass a predefined threshold that signifies the minimum energy density required for material ionization. A 1029 nm, 40 W carbide 275 fs laser was used to ablate sliced adult human teeth and generate the data necessary for testing the models. The volume of material removed, and the shape of the ablated channel were measured using optical profilometry. RESULTS The models fit with the measured ablation efficiency curve against laser fluence for both enamel and dentin, correctly capturing the fluence for optimum ablation and the volume of ablated material per pulse. The detailed shapes of a 400-micrometer wide channel and a single-pulse width channel are accurately predicted using the superposition of the analytical result for a single pulse. CONCLUSIONS The findings have value for planning automated dental restorative treatment using femtosecond lasers. The measurements and analysis give estimates of the optical properties of enamel and dentin irradiated with an infrared femtosecond laser at above-threshold fluence and the proposed models give insight into the physics of femtosecond laser processing of dental hard tissue.
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Affiliation(s)
- Peter L Woodfield
- School of Engineering and Built Environment, Griffith University, Gold Coast, Queensland, Australia
| | - Andrei V Rode
- Department of Quantum Science and Technology, Research School of Physics, Laser Physics Centre, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Dzung Dao
- School of Engineering and Built Environment, Griffith University, Gold Coast, Queensland, Australia
| | - Van Thanh Dau
- School of Engineering and Built Environment, Griffith University, Gold Coast, Queensland, Australia
| | - Steve Madden
- Department of Quantum Science and Technology, Research School of Physics, Laser Physics Centre, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Laurence J Walsh
- School of Dentistry, The University of Queensland, Herston, Queensland, Australia
- Dentroid Pty Ltd, Canberra, Australian Capital Territory, Australia
| | - Heiko Spallek
- Faculty of Medicine and Health, The University of Sydney School of Dentistry, Surry Hills, New South Wales, Australia
| | - Lee Walsh
- Platypus MedTech Consulting Pty Ltd, Barton, Australian Capital Territory, Australia
| | - Andrew J Sutton
- Centre for Gravitational Astrophysics, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Omar Zuaiter
- Dentroid Pty Ltd, Canberra, Australian Capital Territory, Australia
| | - Alaa Habeb
- Dentroid Pty Ltd, Canberra, Australian Capital Territory, Australia
| | - Timothy R Hirst
- Dentroid Pty Ltd, Canberra, Australian Capital Territory, Australia
| | - Ludovic Rapp
- Department of Quantum Science and Technology, Research School of Physics, Laser Physics Centre, Australian National University, Canberra, Australian Capital Territory, Australia
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Rapp L, Madden S, Brand J, Maximova K, Walsh LJ, Spallek H, Zuaiter O, Habeb A, Hirst TR, Rode AV. Investigation of laser wavelength effect on the ablation of enamel and dentin using femtosecond laser pulses. Sci Rep 2023; 13:20156. [PMID: 37978230 PMCID: PMC10656487 DOI: 10.1038/s41598-023-47551-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/15/2023] [Indexed: 11/19/2023] Open
Abstract
We investigated the effect of femtosecond (fs) laser ablation of enamel and dentin for different pulse wavelengths: infrared (1030 nm), green (515 nm), and ultra-violet (343 nm) and for different pulse separations to determine the optimal irradiation conditions for the precise removal of dental hard tissues with the absence of structural and compositional damage. The ablation rates and efficiencies were established for all three laser wavelengths for both enamel and dentin at room temperature without using any irrigation or cooling system, and the surfaces were assessed with optical and scanning electron microscopy, optical profilometry, and Raman spectroscopy. We demonstrated that 515 nm fs irradiation provides the highest rate and efficiency for ablation, followed by infrared. Finally, we explored the temperature variations inside the dental pulp during the laser procedures for all three wavelengths and showed that the maximum increase at the optimum conditions for both infrared and green irradiations was 5.5 °C, within the acceptable limit of temperature increase during conventional dental treatments. Ultra-violet irradiation significantly increased the internal temperature of the teeth, well above the acceptable limit, and caused severe damage to tooth structures. Thus, ultra-violet is not a compatible laser wavelength for femtosecond teeth ablation.
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Affiliation(s)
- Ludovic Rapp
- Laser Physics Centre, Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT, 2600, Australia.
| | - Steve Madden
- Laser Physics Centre, Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT, 2600, Australia
| | - Julia Brand
- Laser Physics Centre, Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT, 2600, Australia
| | - Ksenia Maximova
- Laser Physics Centre, Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT, 2600, Australia
| | - Laurence J Walsh
- The University of Queensland School of Dentistry, Herston, QLD, 4006, Australia
- Dentroid Pty Ltd, Canberra, ACT, 2601, Australia
| | - Heiko Spallek
- Faculty of Medicine and Health, The University of Sydney School of Dentistry, Surry Hills, NSW, 2010, Australia
| | - Omar Zuaiter
- Dentroid Pty Ltd, Canberra, ACT, 2601, Australia
| | - Alaa Habeb
- Dentroid Pty Ltd, Canberra, ACT, 2601, Australia
| | | | - Andrei V Rode
- Laser Physics Centre, Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT, 2600, Australia
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3
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Rapp L, Madden S, Brand J, Walsh LJ, Spallek H, Zuaiter O, Habeb A, Hirst TR, Rode AV. Femtosecond laser dentistry for precise and efficient cavity preparation in teeth. BIOMEDICAL OPTICS EXPRESS 2022; 13:4559-4571. [PMID: 36187240 PMCID: PMC9484447 DOI: 10.1364/boe.463756] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
High fluence focused femtosecond laser pulses were used to perform fast, high precision and minimally damaging cavity cutting of teeth at room temperature without using any irrigation or cooling system. The optimal ablation rates were established for both enamel and dentin, and the surfaces were assessed with optical and scanning electron microscopy, Raman spectroscopy and optical profilometry. No chemical change in the composition of enamel and dentin was observed. We explored temperature variations inside the dental pulp during the laser procedure and showed the maximum increase was 5.5°C, within the acceptable limit of temperature increase during conventional dental treatments.
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Affiliation(s)
- Ludovic Rapp
- Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT 2600, Australia
| | - Steve Madden
- Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT 2600, Australia
| | - Julia Brand
- Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT 2600, Australia
- Centre for Creative and Cultural Research, Faculty of Art and Design, University of Canberra, ACT 2617, Australia
| | - Laurence J. Walsh
- The University of Queensland School of Dentistry QLD 4006, Australia
- Dentroid (Emudent Technologies Pty Ltd), Canberra ACT 2601, Australia
| | - Heiko Spallek
- The University of Sydney School of Dentistry, Faculty of Medicine and Health, NSW 2010, Australia
| | - Omar Zuaiter
- Dentroid (Emudent Technologies Pty Ltd), Canberra ACT 2601, Australia
| | - Alaa Habeb
- Dentroid (Emudent Technologies Pty Ltd), Canberra ACT 2601, Australia
| | - Timothy R. Hirst
- Dentroid (Emudent Technologies Pty Ltd), Canberra ACT 2601, Australia
| | - Andrei V. Rode
- Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT 2600, Australia
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4
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Rapp L, Madden S, Rode AV, Walsh LJ, Spallek H, Nguyen Q, Dau V, Woodfield P, Dao D, Zuaiter O, Habeb A, Hirst TR. Anesthetic-, irrigation- and pain-free dentistry? The case for a femtosecond laser enabled intraoral robotic device. FRONTIERS IN DENTAL MEDICINE 2022. [DOI: 10.3389/fdmed.2022.976097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
By leveraging ultrashort pulse laser and micro-electromechanical systems (MEMS) technologies, we are developing a miniaturized intraoral dental robotic device that clamps onto teeth, is remotely controlled, and equipped with a focusing and scanning system to perform efficient, fast, and ultra-precise laser treatments of teeth and dental restorative materials. The device will be supported by a real-time monitoring system for visualization and diagnostic analysis with appropriate digital controls. It will liberate dentists from repetitive manual operations, physical strain and proximity to the patient's oro-pharyngal area that potentially contains infectious agents. The technology will provide patients with high-accuracy, minimally invasive and pain-free treatment. Unlike conventional lasers, femtosecond lasers can ablate all materials without generating heat, thus negating the need for water irrigation, allowing for a clear field of view, and lowering cross-infection hazards. Additionally, dentists can check, analyze, and perform precise cutting of tooth structure with automatic correction, reducing human error. Performing early-stage diagnosis and intervention remotely will be possible through units installed at schools, rural health centers and aged care facilities. Not only can the combination of femtosecond lasers, robotics and MEMS provide practical solutions to dentistry's enduring issues by allowing more precise, efficient, and predictable treatment, but it will also lead to improving the overall access to oral healthcare for communities at large.
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5
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Aljekhedab F, Zhang W, Haugen HK, Wohl GR, El-Desouki MM, Fang Q. Influence of environmental conditions in bovine bone ablation by ultrafast laser. JOURNAL OF BIOPHOTONICS 2019; 12:e201800293. [PMID: 30680962 DOI: 10.1002/jbio.201800293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 01/22/2019] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
Ultrafast lasers are promising tools for surgical applications requiring precise tissue cutting. Shallow ablation depth and slow rate as well as collateral damage are common barriers limiting the use of laser in clinical applications. Localized cooling with water and/or air jet is known to reduce collateral thermal damage. We studied the influence of environmental conditions including air, compressed air flow, still water and water jet on ablation depth, ablation rate and surface morphology on bovine bone samples with an 800 nm femtosecond laser. At 15 J/cm2 , no thermal effect was observed by electron microscopy and Raman spectroscopy. The experimental results indicate that environmental conditions play a significant role in laser ablation. The deepest cavity and highest ablation rate were achieved under the compressed air flow condition, which is attributed to debris removal during the ablation process. The shallowest ablation depth and lowest ablation rates were associated with water flushing. For surface morphology, smooth surface and the absence of microcracks were observed under air flow conditions, while rougher surfaces and minor microcracks were observed under other conditions. These results suggest that ultrafast ablation of bone can be more efficient and with better surface qualities if assisted with blowing air jet.
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Affiliation(s)
- Fahad Aljekhedab
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
- National Nanotechnology Center, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
| | - Wenbin Zhang
- Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada
- Department of Oral & Cranio-Maxillofacial Surgery, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, National Clinical Research Center of Stomatology, Shanghai, China
| | - Harold K Haugen
- Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Gregory R Wohl
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
- Department of Mechanical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Munir M El-Desouki
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Qiyin Fang
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
- Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada
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6
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de Menezes RF, Harvey CM, de Martínez Gerbi MEM, Smith ZJ, Smith D, Ivaldi JC, Phillips A, Chan JW, Wachsmann-Hogiu S. Fs-laser ablation of teeth is temperature limited and provides information about the ablated components. JOURNAL OF BIOPHOTONICS 2017; 10:1292-1304. [PMID: 28544745 DOI: 10.1002/jbio.201700042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/12/2017] [Accepted: 04/18/2017] [Indexed: 06/07/2023]
Abstract
The goal of this work is to investigate the thermal effects of femtosecond laser (fs-laser) ablation for the removal of carious dental tissue. Additional studies identify different tooth tissues through femtosecond laser induced breakdown spectroscopy (fsLIBS) for the development of a feedback loop that could be utilized during ablation in a clinical setting. Scanning Election Microscope (SEM) images reveal that minimal morphological damages are incurred at repetition rates below the carbonization threshold of each tooth tissue. Thermal studies measure the temperature distribution and temperature decay during laser ablation and after laser cessation, and demonstrate that repetition rates at or below 10kHz with a laser fluence of 40 J/cm2 would inflict minimal thermal damage on the surrounding nerve tissues and provide acceptable clinical removal rates. Spectral analysis of the different tooth tissues is also conducted and differences between the visible wavelength fsLIBS spectra are evident, though more robust classification studies are needed for clinical translation. These results have initiated a set of precautionary recommendations that would enable the clinician to utilize femtosecond laser ablation for the removal of carious lesions while ensuring that the solidity and utility of the tooth remain intact.
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Affiliation(s)
- Rebeca Ferraz de Menezes
- Department of Endodontics/Restorative Dentistry, University of Pernambuco (UPE), 1650 Gal Newton Cavalcanti Avenue, Camaragibe, PE, 54753-020, Brazil
- Center for Biophotonics, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
- Laser Center, University of Pernambuco (UPE), 1650 Gal Newton Cavalcanti Avenue, Camaragibe, PE, 54753-020, Brazil
| | - Catherine Malinda Harvey
- Center for Biophotonics, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
| | - Marleny Elizabeth Márquez de Martínez Gerbi
- Department of Endodontics/Restorative Dentistry, University of Pernambuco (UPE), 1650 Gal Newton Cavalcanti Avenue, Camaragibe, PE, 54753-020, Brazil
- Laser Center, University of Pernambuco (UPE), 1650 Gal Newton Cavalcanti Avenue, Camaragibe, PE, 54753-020, Brazil
| | - Zachary J Smith
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui, China
| | - Dan Smith
- Nikon Research Corporation of America, 12490 N. Rancho Vistoso Blvd., Suite130, Oro Valley, AZ, 85755-1880, USA
| | - Juan C Ivaldi
- Nikon Research Corporation of America, 1399 Shoreway Road, Belmont, CA, 94002-4107, USA
| | - Alton Phillips
- Nikon Research Corporation of America, 12490 N. Rancho Vistoso Blvd., Suite130, Oro Valley, AZ, 85755-1880, USA
| | - James W Chan
- Center for Biophotonics, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
- Department of Pathology and Laboratory Medicine, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
| | - Sebastian Wachsmann-Hogiu
- Center for Biophotonics, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
- Department of Pathology and Laboratory Medicine, University of California-Davis, 2700 Stockton Blvd, Sacramento, CA, 95817, USA
- Intellectual Ventures Laboratory/Global Good, 14360 SE Eastgate Way, Bellevue, WA, 98007, USA
- Department of Bioengineering, McGill University, 817 Sherbrooke Street West, Montreal, Quebec, H3 A0C3, Canada
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Rohde M, Mehari F, Klämpfl F, Adler W, Neukam FW, Schmidt M, Stelzle F. The differentiation of oral soft- and hard tissues using laser induced breakdown spectroscopy - a prospect for tissue specific laser surgery. JOURNAL OF BIOPHOTONICS 2017; 10:1250-1261. [PMID: 27875030 DOI: 10.1002/jbio.201600153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 09/12/2016] [Accepted: 10/26/2016] [Indexed: 06/06/2023]
Abstract
Compared to conventional techniques, Laser surgery procedures provide a number of advantages, but may be associated with an increased risk of iatrogenic damage to important anatomical structures. The type of tissue ablated in the focus spot is unknown. Laser-Induced Breakdown-Spectroscopy (LIBS) has the potential to gain information about the type of material that is being ablated by the laser beam. This may form the basis for tissue selective laser surgery. In the present study, 7 different porcine tissues (cortical and cancellous bone, nerve, mucosa, enamel, dentine and pulp) from 6 animals were analyzed for their qualitative and semiquantitative molecular composition using LIBS. The so gathered data was used to first differentiate between the soft- and hard-tissues using a Calcium-Carbon emission based classifier. The tissues were then further classified using emission-ratio based analysis, principal component analysis (PCA) and linear discriminant analysis (LDA). The relatively higher concentration of Calcium in the hard tissues allows for an accurate first differentiation of soft- and hard tissues (100% sensitivity and specificity). The ratio based statistical differentiation approach yields results in the range from 65% (enamel-dentine pair) to 100% (nerve-pulp, cancellous bone-dentine, cancellous bone-enamel pairs) sensitivity and specificity. Experimental LIBS measuring setup.
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Affiliation(s)
- Maximilian Rohde
- Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052, Erlangen, Germany
- Department of Oral and Maxillofacial Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Glückstraße 11, 91054, Erlangen, Germany
| | - Fanuel Mehari
- Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052, Erlangen, Germany
- Institute of Photonic Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany
| | - Florian Klämpfl
- Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052, Erlangen, Germany
- Institute of Photonic Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany
| | - Werner Adler
- Institute of Biometry and Epidemiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Friedrich-Wilhelm Neukam
- Department of Oral and Maxillofacial Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Glückstraße 11, 91054, Erlangen, Germany
| | - Michael Schmidt
- Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052, Erlangen, Germany
- Institute of Photonic Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany
| | - Florian Stelzle
- Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052, Erlangen, Germany
- Department of Oral and Maxillofacial Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Glückstraße 11, 91054, Erlangen, Germany
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Subramanian K, Gabay I, Ferhanoğlu O, Shadfan A, Pawlowski M, Wang Y, Tkaczyk T, Ben-Yakar A. Kagome fiber based ultrafast laser microsurgery probe delivering micro-Joule pulse energies. BIOMEDICAL OPTICS EXPRESS 2016; 7:4639-4653. [PMID: 27896003 PMCID: PMC5119603 DOI: 10.1364/boe.7.004639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 05/22/2023]
Abstract
We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for fast tissue microsurgery. Delivery of micro-Joules level energies to the tissue was made possible by a large, 31 μm, air-cored inhibited-coupling Kagome fiber. We overcome the fiber's low NA by using lenses made of high refractive index ZnS, which produced an optimal focusing condition with 0.23 NA objective. The optical design achieved a focused laser spot size of 4.5 μm diameter covering a 75 × 75 μm2 scan area in a miniaturized setting. The probe could deliver the maximum available laser power, achieving an average fluence of 7.8 J/cm2 on the tissue surface at 62% transmission efficiency. Such fluences could produce uninterrupted, 40 μm deep cuts at translational speeds of up to 5 mm/s along the tissue. We predicted that the best combination of speed and coverage exists at 8 mm/s for our conditions. The onset of nonlinear absorption in ZnS, however, limited the probe's energy delivery capabilities to 1.4 μJ for linear operation at 1.5 picosecond pulse-widths of our fiber laser. Alternatives like broadband CaF2 crystals should mitigate such nonlinear limiting behavior. Improved opto-mechanical design and appropriate material selection should allow substantially higher fluence delivery and propel such Kagome fiber-based scalpels towards clinical translation.
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Affiliation(s)
- Kaushik Subramanian
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- These authors contributed equally to this work
| | - Ilan Gabay
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- These authors contributed equally to this work
| | - Onur Ferhanoğlu
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
| | - Adam Shadfan
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Michal Pawlowski
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Ye Wang
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Tomasz Tkaczyk
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Adela Ben-Yakar
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- Department of Biomedical Engineering, The University of Texas at Austin, Texas 78712, USA
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9
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Le QT, Bertrand C, Vilar R. Femtosecond laser ablation of enamel. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:65005. [PMID: 27330005 DOI: 10.1117/1.jbo.21.6.065005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/01/2016] [Indexed: 06/06/2023]
Abstract
The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3(PO4)2, at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel’s hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.
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Affiliation(s)
- Quang-Tri Le
- Lisbon University, Instituto Superior Técnico and CeFEMA Center of Physics and Engineering of Advanced Materials, Avenida Rovisco Pais, 1049-001 Lisboa, PortugalbLaboratoire ICMCB-CNRS-UPR9048, 87, Avenue du Dr Albert Schweitzer, 33608 PESSAC Cedex, Franc
| | - Caroline Bertrand
- Laboratoire ICMCB-CNRS-UPR9048, 87, Avenue du Dr Albert Schweitzer, 33608 PESSAC Cedex, France
| | - Rui Vilar
- Lisbon University, Instituto Superior Técnico and CeFEMA Center of Physics and Engineering of Advanced Materials, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
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Al-Hadeethi Y, Al-Jedani S, Razvi MAN, Saeed A, Abdel-Daiem AM, Ansari MS, Babkair SS, Salah NA, Al-Mujtaba A. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation. PLoS One 2016; 11:e0156093. [PMID: 27228169 PMCID: PMC4882067 DOI: 10.1371/journal.pone.0156093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/09/2016] [Indexed: 12/03/2022] Open
Abstract
Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.
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Affiliation(s)
- Y. Al-Hadeethi
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Lithography in Devices Fabrication and Development Research Group, DSR, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - S. Al-Jedani
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - M. A. N. Razvi
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - A. Saeed
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Thamar University, Thamar, Yemen
| | - A. M. Abdel-Daiem
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Physics Department, Faculty of Science, Zagazig University, Zagazig, Egypt
| | | | - Saeed S. Babkair
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Numan A. Salah
- Physics Department, Faculty of Science, Zagazig University, Zagazig, Egypt
| | - A. Al-Mujtaba
- Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
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11
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Gill RK, Smith ZJ, Lee C, Wachsmann-Hogiu S. The effects of laser repetition rate on femtosecond laser ablation of dry bone: a thermal and LIBS study. JOURNAL OF BIOPHOTONICS 2016; 9:171-180. [PMID: 26260774 DOI: 10.1002/jbio.201500144] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/07/2015] [Accepted: 07/09/2015] [Indexed: 06/04/2023]
Abstract
The aim of this study is to understand the effect of varying laser repetition rate on thermal energy accumulation and dissipation as well as femtosecond Laser Induced Breakdown Spectroscopy (fsLIBS) signals, which may help create the framework for clinical translation of femtosecond lasers for surgical procedures. We study the effect of repetition rates on ablation widths, sample temperature, and LIBS signal of bone. SEM images were acquired to quantify the morphology of the ablated volume and fsLIBS was performed to characterize changes in signal intensity and background. We also report for the first time experimentally measured temperature distributions of bone irradiated with femtosecond lasers at repetition rates below and above carbonization conditions. While high repetition rates would allow for faster cutting, heat accumulation exceeds heat dissipation and results in carbonization of the sample. At repetition rates where carbonization occurs, the sample temperature increases to a level that is well above the threshold for irreversible cellular damage. These results highlight the importance of the need for careful selection of the repetition rate for a femtosecond laser surgery procedure to minimize the extent of thermal damage to surrounding tissues and prevent misclassification of tissue by fsLIBS analysis.
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Affiliation(s)
- Ruby K Gill
- Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA
| | - Zachary J Smith
- Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA
| | - Changwon Lee
- Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA
| | - Sebastian Wachsmann-Hogiu
- Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA.
- Department of Pathology, University of California, Davis, Sacramento, CA, 95817, USA.
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12
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Tulea CA, Caron J, Gehlich N, Lenenbach A, Noll R, Loosen P. Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:105007. [PMID: 26469563 DOI: 10.1117/1.jbo.20.10.105007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 09/11/2015] [Indexed: 06/05/2023]
Abstract
Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water–air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2 mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue.
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Affiliation(s)
| | - Jan Caron
- Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany
| | - Nils Gehlich
- Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany
| | - Achim Lenenbach
- Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany
| | - Reinhard Noll
- Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany
| | - Peter Loosen
- Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, GermanybRWTH Aachen University, Chair for Technology of Optical Systems, Steinbachstraße 15, Aachen 52074, Germany
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13
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Domke M, Gavrilova A, Rapp S, Frentzen M, Meister J, Huber HP. Time-resolved microscopy reveals the driving mechanism of particle formation during ultrashort pulse laser ablation of dentin-like ivory. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:76005. [PMID: 26172613 DOI: 10.1117/1.jbo.20.7.076005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/15/2015] [Indexed: 06/04/2023]
Abstract
In dental health care, the application of ultrashort laser pulses enables dental tissue ablation free from thermal side effects, such as melting and cracking. However, these laser types create undesired micro- and nanoparticles, which might cause a health risk for the patient or surgeon. The aim of this study was to investigate the driving mechanisms of micro- and nanoparticle formation during ultrashort pulse laser ablation of dental tissue. Time-resolved microscopy was chosen to observe the ablation dynamics of mammoth ivory after irradiation with 660 fs laser pulses. The results suggest that nanoparticles might arise in the excited region. The thermal expansion of the excited material induces high pressure in the surrounding bulk tissue, generating a pressure wave. The rarefaction wave behind this pressure wave causes spallation, leading to ejection of microparticles.
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Affiliation(s)
- Matthias Domke
- Vorarlberg University of Applied Sciences, Josef Ressel Center for Material Processing with Ultrashort Pulsed Lasers, Research Center for Microtechnology, Hochschulstrasse 1, Dornbirn 6850, Austria
| | - Anna Gavrilova
- Laser Center of Munich University of Applied Sciences, Lothstrasse 34, Munich 80335, Germany
| | - Stephan Rapp
- Laser Center of Munich University of Applied Sciences, Lothstrasse 34, Munich 80335, GermanycFriedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Street 6, Erlangen 91052, Germany
| | - Matthias Frentzen
- Bonn University Dental Faculty, Department of Periodontology, Conservative and Preventive Dentistry, Welschnonnenstrasse 17, Bonn 53111, Germany
| | - Joerg Meister
- Bonn University Dental Faculty, Department of Periodontology, Conservative and Preventive Dentistry, Welschnonnenstrasse 17, Bonn 53111, GermanyeRWTH Aachen University, Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Medical
| | - Heinz P Huber
- Laser Center of Munich University of Applied Sciences, Lothstrasse 34, Munich 80335, Germany
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14
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Kono M, Baldwin KGH, Wain A, Rode AV. Treating the untreatable in art and heritage materials: ultrafast laser cleaning of "cloth-of-gold". LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1596-1604. [PMID: 25561084 DOI: 10.1021/la504400h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort (<picosecond) pulse lasers are emerging as a more appropriate tool for cleaning historic artifacts because of their unique ability to avoid heat- and shock-wave generation, thus minimizing collateral damage of the underlayers, and to remove material with near-nanometer precision. Here we demonstrate the effectiveness of ultrashort pulses by cleaning 19th century military gold braid without any detrimental effects on the gold foil or the underlying silk thread structure. The results are compared with nanosecond-pulse laser treatment that damages the surface structure. By introducing in situ feedback control of the laser ablation via laser-induced breakdown spectroscopy (LIBS) monitoring of the ablated plume, we are able to halt the cleaning process just as the contaminant layer is completely removed. This technique allows ultrafast laser ablation to extend the armory of conservation treatments, enabling restoration of a range of complex and fragile heritage objects previously untreatable by conventional means.
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Affiliation(s)
- Mitsuhiko Kono
- Laser Physics Centre, and ‡Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University ,Canberra, ACT 2601, Australia
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15
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Diwakar PK, Harilal SS, LaHaye NL, Hassanein A, Kulkarni P. The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS. JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY 2013; 28:1420-1429. [PMID: 26664120 PMCID: PMC4673001 DOI: 10.1039/c3ja50088h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes.
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Affiliation(s)
- Prasoon K. Diwakar
- Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Sivanandan S. Harilal
- Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Nicole L. LaHaye
- Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Ahmed Hassanein
- Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Pramod Kulkarni
- National Institute of Occupational Safety and Health, Cincinnati, OH 45213, USA
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16
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Ultrashort pulsed laser (USPL) application in dentistry: basic investigations of ablation rates and thresholds on oral hard tissue and restorative materials. Lasers Med Sci 2013; 29:1775-83. [DOI: 10.1007/s10103-013-1315-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/03/2013] [Indexed: 11/26/2022]
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17
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Luengo MCL, Portillo M, Sánchez JM, Peix M, Moreno P, García A, Montero J, Albaladejo A. Evaluation of micromorphological changes in tooth enamel after mechanical and ultrafast laser preparation of surface cavities. Lasers Med Sci 2012; 28:267-73. [DOI: 10.1007/s10103-012-1144-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 06/21/2012] [Indexed: 10/28/2022]
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18
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Rego Filho FDAMG, Dutra-Corrêa M, Nicolodelli G, Bagnato VS, de Araujo MT. Influence of the hydration state on the ultrashort laser ablation of dental hard tissues. Lasers Med Sci 2012; 28:215-22. [PMID: 22585381 DOI: 10.1007/s10103-012-1118-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/01/2012] [Indexed: 10/28/2022]
Abstract
Since about 40 years, laser-based surgical tools have been used in medicine and dentistry to improve clinical protocols. In dentistry, femtosecond lasers have been claimed to be a potential ablation tool. It would, however, be good to perform a more fundamental investigation to understand ablation interaction mechanisms and possible side effects, depending on different specific components of the target tissue. The goal of this study is to show the changes of ablation characteristics in the femtosecond regime at different levels of structural water within dental hard tissues. Thirty human teeth samples were split into three hydration groups and subdivided into dentin and enamel groups (n = 5). The specimens were irradiated using a 70-fs Ti:sapphire laser (with a 1-kHz repetition rate and a 801-nm wavelength output). Ablation was performed using five different power levels and three exposure times. The results clearly show an inversely proportional dependence of the ablation threshold to the hydration level of the tissues. A known mathematical model was adapted in order to include the influence of the changes on the relative fractional composition of dental hard tissues. This analysis was consistent with the experimental results regarding the ablation threshold. High thermal and mechanical damages were observed as a high repetition rate had been applied. Macroscopic images and scanning electron microscopy images were used to preliminarily analyze both the thermal and mechanical damage thresholds, and their variations according to the hydration level present. By manipulating the hydration states, the modifications in the proportions of the molecules that build dental hard tissues clearly shift, and therefore, the characteristics of a plasma-induced ablation change.
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19
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Jeong D, Tsai PS, Kleinfeld D. Prospect for feedback guided surgery with ultra-short pulsed laser light. Curr Opin Neurobiol 2012; 22:24-33. [PMID: 22088392 PMCID: PMC3763077 DOI: 10.1016/j.conb.2011.10.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 10/20/2011] [Accepted: 10/24/2011] [Indexed: 11/29/2022]
Abstract
The controlled cutting of tissue with laser light is a natural technology to combine with automated stereotaxic surgery. A central challenge is to cut hard tissue, such as bone, without inducing damage to juxtaposed soft tissue, such as nerve and dura. We review past work that demonstrates the feasibility of such control through the use of ultrafast laser light to both cut and generate optical feedback signals via second harmonic generation and laser induced plasma spectra.
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Affiliation(s)
- Diana Jeong
- Department of Physics, University of California at San Diego, La Jolla, CA
| | - Philbert S. Tsai
- Department of Physics, University of California at San Diego, La Jolla, CA
| | - David Kleinfeld
- Department of Physics, University of California at San Diego, La Jolla, CA
- Section of Neurobiology, University of California at San Diego, La Jolla, CA
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20
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Hoy CL, Ferhanoğlu O, Yildirim M, Piyawattanametha W, Ra H, Solgaard O, Ben-Yakar A. Optical design and imaging performance testing of a 9.6-mm diameter femtosecond laser microsurgery probe. OPTICS EXPRESS 2011; 19:10536-52. [PMID: 21643308 DOI: 10.1364/oe.19.010536] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We present the optical design of a 9.6-mm diameter fiber-coupled probe for combined femtosecond laser microsurgery and nonlinear optical imaging. Towards enabling clinical use, we successfully reduced the dimensions of our earlier 18-mm microsurgery probe by half, while improving optical performance. We use analytical and computational models to optimize the miniaturized lens system for off-axis scanning aberrations. The optimization reveals that the optical system can be aberration-corrected using simple aspheric relay lenses to achieve diffraction-limited imaging resolution over a large field of view. Before moving forward with custom lenses, we have constructed the 9.6-mm probe using off-the-shelf spherical relay lenses and a 0.55 NA aspheric objective lens. In addition to reducing the diameter by nearly 50% and the total volume by 5 times, we also demonstrate improved lateral and axial resolutions of 1.27 µm and 13.5 µm, respectively, compared to 1.64 µm and 16.4 µm in our previous work. Using this probe, we can successfully image various tissue samples, such as rat tail tendon that required 2-3 × lower laser power than the current state-of-the-art. With further development, image-guided, femtosecond laser microsurgical probes such as this one can enable physicians to achieve the highest level of surgical precision anywhere inside the body.
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Affiliation(s)
- Christopher L Hoy
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
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21
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Schoenly JE, Seka W, Rechmann P. Investigation into the optimum beam shape and fluence for selective ablation of dental calculus at λ
= 400 nm. Lasers Surg Med 2010; 42:51-61. [DOI: 10.1002/lsm.20884] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Lim YC, Altman KJ, Farson DF, Flores KM. Micropillar fabrication on bovine cortical bone by direct-write femtosecond laser ablation. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:064021. [PMID: 20059259 DOI: 10.1117/1.3268444] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We investigated fabrication of cylindrical micropillars on bovine cortical bone using direct-write femtosecond laser ablation. The ablation threshold of the material was measured by single-pulse ablation tests, and the incubation coefficient was measured from linear scanned ablation tests. A motion system was programmed to apply multiple layers of concentric rings of pulses to machine pillars of various diameters and heights. The diameter of the top surface of the pillar was found to steadily decrease due to incubation of damage from successive layers of pulses during the machining process. Pillar top diameter was predicted based on a paraxial beam fluence approximation and single-pulse ablation threshold and incubation coefficient measurements. Pillar diameters predicted as successive layers of pulses were applied were well-matched to experiments, confirming that femtosecond laser ablation of the cortical bone was well-modeled by single-pulse ablation threshold measurements and an incubation coefficient.
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Affiliation(s)
- Yong C Lim
- The Ohio State University, Laboratory for Multiscale Processing and Characterization, 1248 Arthur E. Adams Drive, Columbus, Ohio 43210, USA
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23
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Abstract
Femtosecond laser ablation permits non-invasive surgeries in the bulk of a sample with submicrometer resolution. We briefly review the history of optical surgery techniques and the experimental background of femtosecond laser ablation. Next, we present several clinical applications, including dental surgery and eye surgery. We then summarize research applications, encompassing cell and tissue studies, research on C. elegans, and studies in zebrafish. We conclude by discussing future trends of femtosecond laser systems and some possible application directions.
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Affiliation(s)
- Samuel H Chung
- School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, MA 02138, USA.
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24
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Lee H, Jeong YU, Chan KF. The Advent of Laser Therapies in Dermatology and Urology: Underlying Mechanisms, Recent Trends and Future Directions. ACTA ACUST UNITED AC 2009. [DOI: 10.3807/josk.2009.13.3.321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Fränzel W, Gerlach R. The irradiation action on human dental tissue by X-rays and electrons--a nanoindenter study. Z Med Phys 2009; 19:5-10. [PMID: 19459580 DOI: 10.1016/j.zemedi.2008.10.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
It is known that ionizing radiation is used in medicine for Roentgen diagnostics and for radiation therapy. The radiation interacts with matter, in particular with biological one, essentially by scattering, photoelectric effect, Compton effect and pair production. To what extent the biological material is changed thereby, depends on the type and the amount of radiation energy, on the dose and on the tissue constitution. In modern radiation therapy two different kinds of radiation are used: high energy X-rays and electron radiation. In the case of head-neck tumors the general practice is an irradiation with high energy X-rays with absorbed dose to water up to 70 Gy. Teeth destruction has been identified as a side effect during irradiation. In addition, damage to the salivary glands is often observed which leads to a decrease or even the complete loss of the salivary secretion (xerostomia). This study shows how the different energy and radiation types damage the tooth tissue. The effects of both, high X-ray energy and high energy electrons, on the mechanical properties hardness and elasticity of the human dental tissue are measured by the nanoindentation technique. We compare these results with the effect of the irradiation of low X-ray energy on the dental tissue.
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Affiliation(s)
- Wolfgang Fränzel
- Department of Physics, Martin Luther University Halle, 06099 Halle, Germany.
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26
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Rode AV, Gamaly EG, Luther-Davies B, Taylor BT, Graessel M, Dawes JM, Chan A, Lowe RM, Hannaford P. Precision ablation of dental enamel using a subpicosecond pulsed laser. Aust Dent J 2008; 48:233-9. [PMID: 14738125 DOI: 10.1111/j.1834-7819.2003.tb00036.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this study we report the use of ultra-short-pulsed near-infrared lasers for precision laser ablation of freshly extracted human teeth. The laser wavelength was approximately 800nm, with pulsewidths of 95 and 150fs, and pulse repetition rates of 1kHz. The laser beam was focused to an approximate diameter of 50microm and was scanned over the tooth surface. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain below 5 degrees C when the tooth was air-cooled during laser treatment. The surface preparation of the ablated teeth, observed by optical and electron microscopy, showed no apparent cracking or heat effects, and the hardness and Raman spectra of the laser-treated enamel were not distinguishable from those of native enamel. This study indicates the potential for ultra-short-pulsed lasers to effect precision ablation of dental enamel.
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Affiliation(s)
- A V Rode
- Research School of Physical Science and Engineering, Australian National University, Canberra, Australian Capital Territory
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27
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Vila Verde A, Ramos MMD, Stoneham AM. The role of mesoscopic modelling in understanding the response of dental enamel to mid-infrared radiation. Phys Med Biol 2007; 52:2703-17. [PMID: 17473346 DOI: 10.1088/0031-9155/52/10/005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Human dental enamel has a porous mesostructure at the nanometre to micrometre scales that affects its thermal and mechanical properties relevant to laser treatment. We exploit finite-element models to investigate the response of this mesostructured enamel to mid-infrared lasers (CO(2) at 10.6 microm and Er:YAG at 2.94 microm). Our models might easily be adapted to investigate ablation of other brittle composite materials. The studies clarify the role of pore water in ablation, and lead to an understanding of the different responses of enamel to CO(2) and Er:YAG lasers, even though enamel has very similar average properties at the two wavelengths. We are able to suggest effective operating parameters for dental laser ablation, which should aid the introduction of minimally-invasive laser dentistry. In particular, our results indicate that, if pulses of approximately 10 micros are used, the CO(2) laser can ablate dental enamel without melting, and with minimal damage to the pulp of the tooth. Our results also suggest that pulses with 0.1-1 micros duration can induce high stress transients which may cause unwanted cracking.
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Affiliation(s)
- A Vila Verde
- Department of Chemical Engineering, Fenske Laboratory, The Pennsylvania State University, University Park, PA 16802, USA
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28
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