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Khosroshahi ME, Farahani FD, Ghazanfari L, Woll-Morison V. Dynamic characterization of indocyanine green-assisted dental caries ablation with continuous diode laser using thermal imaging and fluorescence spectroscopy. Lasers Med Sci 2021; 36:667-674. [PMID: 32772274 DOI: 10.1007/s10103-020-03118-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/01/2020] [Indexed: 11/21/2022]
Abstract
We describe the time-resolved thermal changes in indocyanine green (ICG)-assisted diode laser ablation of dental caries as a potential technique for painless treatment based on the selective photoabsorption and controlled photothermal ablation. Static ablation mode produced a higher temperature rise compared with scanning mode due to localized accumulation of heat. A temperature rise between 45-80 and 70-95 °C was obtained after 20 s that corresponded to 29 and 80 W cm-2, respectively. The temperature of the tooth surface increased by irradiation time, and it behaved linearly up to 70 °C at 29 and 80 W cm-2. A maximum ablation per area of about 0.3 and 0.45 mg cm-2 was achieved after 80 s exposure at 29 and 80 W cm-2, respectively. A statistically significant difference is observed in mean carious teeth weight at various exposure times between low and high irradiances. A thermal penetration depth of 0.8-9 mm is determined for 1-100 s of exposure time. The IR thermal imaging of ICG temperature as a function of exposure time showed a linear increase for 60 s beyond which it deviated. The laser-induced fluorescence spectroscopy indicated that the ICG quality can be altered during the course of irradiation, which in our case, it corresponded to ≈ 78% loss of signal within 23 min of exposure. The caries removal experiment was performed within 100 s corresponding to ≈ 7% loss. We believe that the application of the above-combined technique can be utilized as a monitoring device to control the ablation interaction process.
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Affiliation(s)
- Mohammad E Khosroshahi
- Laser & Nanobiophotonics Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
- Nanobiophotonics & Biomedical Research Laboratory, MIS-Electronics Inc., Richmond Hill, Canada.
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada.
| | - Faezeh D Farahani
- Laser & Nanobiophotonics Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
- Medric Teb Co., Tehran, Iran
| | - Lida Ghazanfari
- Laser & Nanobiophotonics Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
- Eshelman School of Pharmacy, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Vaughan Woll-Morison
- Nanobiophotonics & Biomedical Research Laboratory, MIS-Electronics Inc., Richmond Hill, Canada
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Engelbach C, Dehn C, Bourauel C, Meister J, Frentzen M. Ablation of carious dental tissue using an ultrashort pulsed laser (USPL) system. Lasers Med Sci 2014; 30:1427-34. [PMID: 24865391 DOI: 10.1007/s10103-014-1594-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 05/12/2014] [Indexed: 10/25/2022]
Abstract
The aim of the study was to investigate the efficiency of caries removal employing an ultrashort pulsed laser (USPL) and to compare the results regarding to the ablation rate of sound enamel and dentin including surface texture. The study was performed with 59 freshly extracted carious human teeth. Two cavities with an edge length of 1 × 1 mm per tooth were created: one in the dental decay and one in sound hard tissue. For this purpose a 9-W Nd:YVO4 laser with a center wavelength of 1,064 nm and a pulse duration of 8 ps at a repetition rate of 500 kHz was used. A scanner system moved the laser beam across the surface with a scan speed of 2,000 mm/s. Ablated volume and roughness R z of the cavity ground were measured using an optical profilometer. Subsequently, the specimens were cut to undecalcified sections for histological investigations. The removal of dental decay (dentin, 14.9 mm(3)/min; enamel, 12.8 mm(3)/min) was significantly higher (p < 0.05) compared to the removal of sound tissues (dentin, 4.2 mm(3)/min; enamel, 3.8 mm(3)/min). The arithmetic means of the surface roughness R z were 8.5 μm in carious enamel, 15.43 μm in carious dentin, 4.83 μm in sound enamel and 5.52 μm in sound dentin. Light microscopic investigations did not indicate any side effects in the surrounding tissues. Regarding the ablation rate of dental decay using the USPL system, caries removal seems to be much more efficient for cavity preparation.
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Affiliation(s)
- Christoph Engelbach
- Department of Operative and Preventive Dentistry, Bonn University, Dental Faculty, Welschnonnenstrasse 17, 53111, Bonn, Germany
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Walsh L. Pulpal Safety Considerations for Irradiation of Dental Hard Tissues with Carbon Dioxide Lasers. ACTA ACUST UNITED AC 2010. [DOI: 10.1111/j.1747-4477.1993.tb00388.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Figueiredo de Magalhães M, Neto Ferreira RA, Grossi PA, de Andrade RM. Measurement of thermophysical properties of human dentin: effect of open porosity. J Dent 2008; 36:588-94. [PMID: 18547708 DOI: 10.1016/j.jdent.2008.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2007] [Revised: 04/05/2008] [Accepted: 04/08/2008] [Indexed: 11/27/2022] Open
Abstract
UNLABELLED In dentistry caries removal can be performed with rotatory instruments or high intensity laser. Both techniques can heat the tooth and harm the pulp. The literature review about the measurement of human dentin thermophysical properties revealed a great variation of the values obtained by several authors, and most of the studies are outdated. Most of these studies have not directly measured the thermal diffusivity of human dentin, and the reported values are calculated values based on measurements of conductivity, density and specific heat. OBJECTIVE The aim of the present study was to measure human dentin thermal diffusivity, density, open porosity and specific heat, and then to calculate its thermal conductivity and analyze the influence of open porosity in these properties. METHOD The methods used were: flash laser method for measuring thermal diffusivity, method of penetration and immersion with xylol for density and open porosity and differential scanning calorimetry for measuring specific heat. Calculated results of the thermal conductivity are shown as well. RESULT Results of diffusivity, density, open porosity, specific heat and thermal conductivity of measurements performed on five samples are presented and compared with results of other authors. The open porosity of the samples varied between 1.11% and 3.08% of the sample volume, corresponding to densities ranging between 2090 and 2400 kg m(-3), thermal diffusivity: 0.199 and 0.265 x 10(-6)m2 s(-1), specific heat: 872.5 and 1181.0 J kg(-1)K(-1), thermal conductivity: 0.363 and 0.666 W m(-1)K(-1). CONCLUSION It has been found that there exist a strong correlation between the open porosity of human dentin and its thermal conductivity and density. Both human dentin thermal conductivity and density decrease with the increasing of open porosity, with a confidence of at least 98% and 96.6%, respectively.
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Affiliation(s)
- Manoelita Figueiredo de Magalhães
- Departamento de Engenharia Mecânica, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos 6627, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
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Ciaramicoli MT, Carvalho RCR, Eduardo CP. Treatment of cervical dentin hypersensitivity using neodymium: Yttrium-aluminum-garnet laser. Clinical evaluation. Lasers Surg Med 2003; 33:358-62. [PMID: 14677164 DOI: 10.1002/lsm.10232] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVE The incidence of cervical dentinal hypersensitivity is related to the high number of non-carious cervical lesions. This clinical research was developed in order to evaluate the Nd:YAG laser treatment of cervical dentin hypersensitivity after attempting the removal and control of etiologic factor after two different stimuli. STUDY DESIGN/MATERIALS AND METHODS Twenty patients participated in this study in a total of 145 teeth, where 104 received the Nd:YAG laser treatment and 41 remained as control. RESULTS The results showed that there was statistically significant reduction of hypersensitivity as for the groups that received the treatment with Nd:YAG laser, as for the control teeth. However, the reduction of cervical dentinal hypersensitivity was statistically greater when there was the association of the removal of etiologic factors with the application of Nd:YAG laser. CONCLUSIONS We concluded that the laser irradiation was effective in the treatment of cervical dentin hypersensitivity after 6 months.
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Affiliation(s)
- Márcia T Ciaramicoli
- Department of Restorative Dentistry, School of Dentistry, University of São Paulo-SP, Brazil 05580-900
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McDonald AV, Claffey NM, Pearson GJ, Blau W, Setchell DJ. Effect of Nd:YAG radiation at millisecond pulse duration on dentine crater depth. Lasers Surg Med 2001; 27:213-23. [PMID: 11013383 DOI: 10.1002/1096-9101(2000)27:3<213::aid-lsm3>3.0.co;2-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVE The effect of laser parameters on laser-dentine interaction has not been explored fully. This in vitro study investigated the effect on dentine crater depth of Nd:YAG laser radiation with varying repetition rates, total delivered energy, and dentine site either dyed or undyed. STUDY DESIGN/MATERIALS AND METHODS One hundred forty-four caries-free third molars were sectioned transversely to provide 288 upper and lower cut surfaces. The upper surfaces were dyed (IR5). These upper and lower cut surfaces were exposed to an Nd:YAG laser with a 7 millisecond (msec) pulse duration, pulse repetition rates (RR) of 2. 5, 5.4, and 10.5 Hz, and four total energies (2.28, 2.64, 3.6, 4.2 joules). Dentine crater depth was measured by using a Reflex microscope. Results were statistically analysed with analysis of variance. RESULTS Crater depth increased with increase in total delivered energy and in dyed and inner dentine sites (P<0.0001) but decreased with increasing repetition rate (P< 0.0001). CONCLUSIONS Increasing energy, dyed, and inner dentine sites produced deeper craters.
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Affiliation(s)
- A V McDonald
- Department of Restorative Dentistry, Eastman Dental Institute and Hospital for Oral Health Care Sciences, University of London, London, United Kingdom.
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Abstract
BACKGROUND AND OBJECTIVE Successful non-devitalizing treatment of localized pulpal lesions in mature teeth is not ensured using conventional endodontic techniques. The objective of this study was to evaluate CO2 laser surgical treatment of pulpal exposures in canine patients. STUDY DESIGN/MATERIALS AND METHODS 17 permanent teeth with pulpal exposures of < or = 48 h duration received localized laser pulp surgery. Laser Parameters: pulse duration: 0.01 s, pulse interval: 1.0 s, spot size: 0.004 cm2, fluence: 276 J/cm2. Exposures were dressed with CaOH and Glass ionomer. Clinical and radiographic evaluations were performed by one blinded clinician 24 and 52 weeks after treatment. RESULTS 15/17 laser-treated teeth assessed over > or = 1 year post-treatment remained clinically and radiographically healthy. CONCLUSION These results demonstrate the feasibility of using the CO2 laser for localized pulp surgery. Further studies must optimize laser parameters and identify the range of clinical pathologies which can be treated using this modality.
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Affiliation(s)
- P Wilder-Smith
- Beckman Laser Institute and Medical Center, University of California, Irvine 92612, USA.
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Cassatly MG, Rostock M, Gocke MW. Iatrogenic osteonecrosis of the maxilla caused by laser injury. J Oral Maxillofac Surg 1999; 57:184-6. [PMID: 9973128 DOI: 10.1016/s0278-2391(99)90236-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Meffert JJ, Cagna DR, Meffert RM. Treatment of oral granulation tissue with the flashlamp pulsed dye laser. Dermatol Surg 1998; 24:845-8. [PMID: 9723048 DOI: 10.1111/j.1524-4725.1998.tb04261.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Surgical excision and debridement is the standard therapy for cutaneous and intraoral pyogenic granulomas (PGs). Occasionally the mass of granulation tissue proves unresponsive to the usual treatment methods. OBJECTIVE We report a case in which the flashlamp pulsed dye laser (PDL), previously reported as useful in cutaneous PGs, was used in a patient with persistent granulation tissue around dental implant posts. METHODS An illustrative case is presented with a brief discussion of the use of lasers in dentistry and in the treatment of PGs. RESULTS Previously resolute tissue responded well to a series of treatments with the PDL. CONCLUSION The PDL may have utility in this oral condition, providing a new venue for cooperation between dentists and dermatologists.
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Affiliation(s)
- J J Meffert
- Department of Dermatology, San Antonio Uniformed Services Health Education Consortium, Brooke Army Medical Center, Fort Sam Houston, Texas, USA
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Brugnera Júnior A, Rosso N, Duarte D, Pinto AC, Genovese W. The use of carbon dioxide laser in pit and fissure caries prevention: clinical evaluation. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 1998; 15:79-82. [PMID: 9612182 DOI: 10.1089/clm.1997.15.79] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this 4-year follow-up in vivo controlled study, 112 human permanent first molars from children between 6 and 11 years old were used to investigate the viability of the carbon dioxide (CO2) laser in promoting caries-free occlusal surfaces in permanent molars as an isolated form of treatment or associated with conventional fissure sealants. The findings suggest that occlusal caries prevention only by means of CO2 laser irradiation is not effective; that the utilization of photoactivated sealants, as well as its association with CO2 laser, applied over the occlusal fissures, are effective means of preventing occlusal caries, and that the application of CO2 laser over occlusal fissures prior to the application of a photoactivated fissure sealant improves the retention of the sealant.
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Mattson JS, Blankenau R, Keene JJ. Case report. Use of an argon laser to treat drug-induced gingival overgrowth. J Am Dent Assoc 1998; 129:78-83. [PMID: 9448349 DOI: 10.14219/jada.archive.1998.0024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This article explores the use of an argon laser to treat severe drug-induced gingival overgrowth. The patient was being treated with phenytoin (Dilantin, Parke-Davis), cyclosporine and a calcium channel blocker. He had undergone a kidney transplantation and had insulin-dependent diabetes mellitus. He had severe gingival overgrowth, which prevented him from wearing his removable prostheses, and a superimposed Candida albicans infection. An argon laser was used to excise the gingival overgrowth so new maxillary and mandibular prostheses could be fabricated.
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Affiliation(s)
- J S Mattson
- Department of Periodontics, Creighton University School of Dentistry, Omaha, Neb. 68178, USA
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12
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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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Abstract
BACKGROUND AND OBJECTIVE Several lasers have been explored for hard dental tissue applications; used alone they have resulted in potentially harmful temperature increases in the pulp chamber. MATERIALS AND METHODS An Er:YAG laser (lambda = 2.94 microns) was used to ablate hard dental tissues. Ablation rates with and without a water-cooling spray were measured. Subsequent experiments investigated the cooling effects of the water. Initially single channels were drilled into dentin; further studies involved ablating rectangular areas with repetition rates up to 10 Hz. RESULTS The water spray minimally reduced the ablation rates of dentin and did not affect the ablation rates of enamel. The water spray effectively cooled the teeth; while using the maximum average power investigated (10 Hz, 360 mJ/pulse), a water flow rate of 4.5 ml/min limited the temperature rise in the pulp chamber to less than 3 degrees C. CONCLUSION The studies confirm the feasibility of using an Er:YAG laser in conjunction with a water spray to safely and effectively remove hard dental tissues.
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Affiliation(s)
- S R Visuri
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
BACKGROUND AND OBJECTIVE Several lasers have been explored for hard dental tissue applications; used alone they have resulted in potentially harmful temperature increases in the pulp chamber. MATERIALS AND METHODS An Er:YAG laser (lambda = 2.94 microns) was used to ablate hard dental tissues. Ablation rates with and without a water-cooling spray were measured. Subsequent experiments investigated the cooling effects of the water. Initially single channels were drilled into dentin; further studies involved ablating rectangular areas with repetition rates up to 10 Hz. RESULTS The water spray minimally reduced the ablation rates of dentin and did not affect the ablation rates of enamel. The water spray effectively cooled the teeth; while using the maximum average power investigated (10 Hz, 360 mJ/pulse), a water flow rate of 4.5 ml/min limited the temperature rise in the pulp chamber to less than 3 degrees C. CONCLUSION The studies confirm the feasibility of using an Er:YAG laser in conjunction with a water spray to safely and effectively remove hard dental tissues.
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Affiliation(s)
- S R Visuri
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
Lasers may be useful in uncovering submerged implants or in removing contaminants from "ailing" implants. The purposes of this study were to record temperature changes at the bone-titanium implant interface when using a CO2 laser to: 1) uncover the implant at second stage surgery; and 2) "decontaminate" exposed implant threads. Scanning electron microscopy (SEM) was used to characterize surface changes of lased implants, both uncontaminated or contaminated with blood or saliva. In part one, 28 titanium implants, measuring 3.75 mm by 7 to 20 mm, were placed into room temperature, fresh, resected pig mandibles and covered with a flap of gingiva. The overlying tissue was removed with a CO2 laser at different power levels. Bone-implant interface temperatures were measured with a thermocouple near the top of the implant, and 5 to 7 mm apical to the osseous crest. The effects of implant size, power level, tissue thickness, and operation time were evaluated. In part two, 5 mm by 4 mm bony dehiscences were created on 3 implants in one mandible and the exposed fixture threads lased at varying times and power levels. The results from part one showed temperature increases at the top thermocouple ranged from 4.2 to 16.8 degrees C and increases at the bottom thermocouple ranged from 2.0 to 11.5 degrees C. The results from part two showed temperature increases at the top thermocouple ranged from 1.2 to 11.7 degrees C and increases at the bottom thermocouple from 0.0 to 5.0 degrees C. If baseline ambient temperatures are 37 degrees C, then the temperature at the bone-implant interface might exceed 50 degrees C. SEM revealed no gross surface changes in lased uncontaminated implants, but laser treatment alone of contaminated implants failed to completely remove saliva or blood. Further study is needed regarding temperature increases and surface changes induced by lasers that may adversely affect osseointegration.
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Affiliation(s)
- D K Oyster
- U.S. Navy, Periodontics Department, Branch Dental Clinic, Mayport, FL, USA
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Anić I, Matsumoto K. Dentinal heat transmission induced by a laser-softened gutta-percha obturation technique. J Endod 1995; 21:470-4. [PMID: 8537791 DOI: 10.1016/s0099-2399(06)81531-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In this study, intracanal laser-softened gutta-percha, Ultrafil, and intracanal laser-cured composite resin techniques were compared with respect to the temperature elevation induced on the outer root surface. The temperature at the root surface of 50 single-rooted teeth was measured using a thermovision camera. Argon laser produced a rise in temperature of +12.9 degrees C (gutta-percha) and +13.3 degrees C (composite resin), respectively. The CO2 laser produced +10.3 degrees C and Nd:YAG laser produced the highest temperature elevation of +14.4 degrees C. Low-temperature gutta-percha obturation technique did not produce a measurable temperature change on the external root surfaces.
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Affiliation(s)
- I Anić
- Department of Dental Pathology, School of Dentistry, University of Zagreb, Croatia
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Mazouri Z, Walsh LJ. Damage to dental composite restorations following exposure to CO2 laser radiation. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 1995; 13:73-6. [PMID: 10150574 DOI: 10.1089/clm.1995.13.73] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Damage to tooth structure is a major hazard in the use of infrared lasers for oral surgical procedures. While the effects of laser exposure on dental enamel and dentine are well characterized, there are no data on the effects of laser exposure on dental composite materials, which are widely used in tooth-colored restorations. This study examined surface changes in several dental composites exposed to CO2 laser radiation for 200 msec. Surface changes, such as ablation, combustion, and melting, occurred even at relatively low power densities (340 W/cm2), with greater effects occurring in composites than in "compomers" (glass iomomer-composite mixtures). These findings indicate that nonmetallic dental restorations are prone to damage from inadvertent laser exposure. Clinicians must be aware of this hazard and employ measures to protect both natural tooth structure and restorations when performing intraoral laser surgery.
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Affiliation(s)
- Z Mazouri
- Department of Dentistry, University of Queensland, Brisbane, Australia
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Arrastia AM, Wilder-Smith P, Berns MW. Thermal effects of CO2 laser on the pulpal chamber and enamel of human primary teeth: an in vitro investigation. Lasers Surg Med 1995; 16:343-50. [PMID: 7651055 DOI: 10.1002/lsm.1900160405] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND AND OBJECTIVE Thermal effects of direct exposure of the pulp chamber to CO2 laser irradiation were evaluated and potentially safe parameters for its clinical application were determined. STUDY DESIGN/MATERIALS AND METHODS Using conventional methods, the pulp chambers of freshly extracted primary cuspids were exposed and then subjected to CO2 laser irradiation at the following parameters: 2, 4, 6, 8, 10, 15, and 20 Watts power settings; 0.76 mm diameter spot size; total energy densities between 4-1,058 J/cm2; exposure time between .01-60 s. Exposures in the continuous wave mode were performed in some specimens. In others, single firings of a .01 s pulse duration and a 1 s pulse interval were conducted. Temperature measurements were conducted using a thermocouple and thermal camera. RESULTS Significant statistical differences in maximum temperature rise on enamel were observed in groups that received total energy densities > or = 8 J/cm2 (P < or = 0.01); within the pulp chambers these were observed in groups that used > or = 44 J/cm2 (P < or = 0.01). CONCLUSION Parameters appropriate for pulpotomy were observed at energy densities up to 176 J/cm2 in the continuous wave mode and 264 J/cm2 using single pulses, wherein temperature rises below 5.5 degrees C were recorded on tooth surface.
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Affiliation(s)
- A M Arrastia
- Beckman Laser Institute and Medical Clinic, University of California, Irvine 92715, USA
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Wigdor HA, Walsh JT, Featherstone JD, Visuri SR, Fried D, Waldvogel JL. Lasers in dentistry. Lasers Surg Med Suppl 1995; 16:103-33. [PMID: 7769957 DOI: 10.1002/lsm.1900160202] [Citation(s) in RCA: 234] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Since the development of the ruby laser by Maiman in 1960, there has been great interest among dental practitioners, scientists, and patients to use this tool to make dental treatment more pleasant. Oral soft tissue uses are becoming more common in dental offices. The possible multiple uses of lasers in dentistry, beyond soft tissue surgery and dental composite curing, unfortunately, have not yet been realized clinically. These include replacement of the dental drill with a laser, laser dental decay prevention, and laser decay detection. The essential question is whether a laser can provide equal or improved treatment over conventional care. Safe use of lasers also must be the underlying goal of proposed or future laser therapy. With the availability and future development of different laser wavelengths and methods of pulsing, much interest is developing in this growing field. This article reviews the role of lasers in dentistry since the early 1960s, summarizes some research reports from the last few years, and proposes what the authors feel the future may hold for lasers in dentistry.
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Affiliation(s)
- H A Wigdor
- Ravenswood Hospital Medical Center, Wenske Laser Center, Chicago, IL 60640, USA
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SANDFORD M, WALSH L. Differential Thermal Effects of Pulsed vs. Continuous CO2Laser Radiation on Human Molar Teeth. ACTA ACUST UNITED AC 1994. [DOI: 10.1089/clm.1994.12.139] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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White JM, Fagan MC, Goodis HE. Intrapulpal temperatures during pulsed Nd:YAG laser treatment of dentin, in vitro. J Periodontol 1994; 65:255-9. [PMID: 8164119 DOI: 10.1902/jop.1994.65.3.255] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Lasers are being used for soft tissue removal, caries removal, and treatment of root surface sensitivity. One concern for laser safety is that the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occur during gingival excision, superficial caries removal, and modification of the dentin surface for treatment of root surface sensitivity, a 2 mm2 area of the external root surface was uniformly irradiated with a pulsed Nd:YAG laser using a 320 microns diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high speed handpiece with air coolant were also recorded. Repeated measures ANOVA (P < or = 0.05) indicated that intrapulpal temperatures increased as a function of power, frequency, and time. Intrapulpal temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd:YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, should not cause devitalizing intrapulpal temperature rises.
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Affiliation(s)
- J M White
- Department of Restorative Dentistry, University of California, San Francisco
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22
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Walsh LJ. Clinical evaluation of dental hard tissue applications of carbon dioxide lasers. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 1994; 12:11-5. [PMID: 10146710 DOI: 10.1089/clm.1994.12.11] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This clinical study examined the pulpal safety of selected CO2 laser hard tissue applications. A total of 187 hard tissue procedures were performed on 54 patients. The mean period of follow-up following laser treatment was 13.5 months (range 2-24 months). The procedures included etching (n = 96), desensitizing (n = 56), laser-enhanced fluoride (n = 28), treatment of external resorption (n = 4), and pulp capping or pulpotomy (n = 3). Only the latter two procedure types were performed with anesthesia. The total irradiation received during these procedures ranged from 2 to 12 J. No patients complained of sensation or discomfort during any procedure. Pulp vitality was maintained in all teeth, and no instances of postlasing thermal sensitivity or pulpitis were reported. These results indicate that pulp vitality can be maintained provided that conditions of irradiance are controlled carefully to minimize thermal effects.
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Affiliation(s)
- L J Walsh
- Department of Dentistry, University of Queensland, Brisbane, Australia
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23
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Abstract
The diagnosis of small lesions in pit and fissure sites is becoming increasingly problematical. This study was designed to evaluate, in vitro, the potential use of a carbon dioxide (CO2) laser technique as an aid to the diagnosis of incipient pit and fissure caries. Vaporization of the organic material in the 'early' carious lesion should lead to its carbonization and thus make it more conspicuous. Pilot studies were carried out to identify lasing parameters which produced no visible effect on sound enamel but which caused charring (carbonization) of white spot fissure lesions. Fifty extracted human molars and premolars were air-polished on the occlusal surfaces and independently scored clinically for caries, both before and after lasing. The teeth were subsequently sectioned and examined histologically. Of the 37 sites histologically scored as sound or exhibiting precavitation lesions, eight were correctly scored as sound both prelasing and postlasing. Of the 29 precavitation lesions detected histologically, five were detected clinically prelasing and 11 were detected postlasing. This 21% difference in the sensitivity of caries diagnosis between the prelasing and postlasing examinations was statistically significant (at the 95% level). There were no false-positive caries diagnoses. Further research, in particular the refining of lasing parameters employed, is indicated.
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Affiliation(s)
- C Longbottom
- Department of Dental Health, Dental School, Dundee, UK
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25
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Arcoria CJ, Lippas MG, Vitasek BA. Enamel surface roughness analysis after laser ablation and acid-etching. J Oral Rehabil 1993; 20:213-24. [PMID: 8468631 DOI: 10.1111/j.1365-2842.1993.tb01603.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Laser-roughened enamel surfaces have been shown to provide for greater acid-resistance and enhanced restorative material/enamel bond strength. Extracted tooth enamel was irradiated with several lasers: CO2/Nd:YAG (CW), CO2 (RSP), Nd:YAG (CW), Nd:YAG (Q-switched), Argon (CW), and Ar:F excimer. Additional teeth were acid-etched. Energy densities were standardized at 25.47 J/cm2 for all mediums. Surface profile analyses were conducted with a profilometer to determine the amount of enamel surface roughness. The acid-etched samples exhibited both a greater amount of surface roughness and a qualitatively different type of enamel surface morphology than the laser-treated specimens. Independent use of the CO2 and Nd:YAG beams exhibited a moderate amount of roughness, while the coaxial CO2/Nd:YAG beam displayed surface roughness approaching that of the acid-etch samples. Different laser mediums produce enamel surface morphologies that are characteristic of a variety of inherent lasing parameters.
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Affiliation(s)
- C J Arcoria
- Department of Operative Dentistry, Baylor College of Dentistry, Dallas, Texas 75246
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26
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Tocchio RM, Williams PT, Mayer FJ, Standing KG. Laser debonding of ceramic orthodontic brackets. Am J Orthod Dentofacial Orthop 1993; 103:155-62. [PMID: 8427220 DOI: 10.1016/s0889-5406(05)81765-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Laser light energy has been shown in other studies to degrade resins by thermal softening, thermal ablation, or photoablation. If this technology could be successfully applied to bracket debonding, fracturing of both bracket and enamel during debonding might be eliminated. Both polycrystalline alumina and single crystal alumina (sapphire) ceramic orthodontic brackets were bonded to the labial surfaces of lower deciduous bovine incisor teeth with the acid-etch technique as currently practiced in dentistry. Under an externally applied stress of either zero or 0.8 MPa, the brackets were debonded by irradiating the labial surfaces of the brackets with laser light at wavelengths of 248 nm, 308 nm, and 1060 nm, and at light power densities of between about 3 and 33 W/cm2. Debonding times were measured, and the surfaces created by debonding were examined with both light and scanning electron microscopy to determine the extent of bracket and enamel damage. The results showed that under the conditions of this study, no enamel or bracket damage was present in any sample. The polycrystalline brackets debonding times were about 3 seconds, 5 seconds, and 24 seconds for 248 nm, 308 nm, and 1060 nm of radiation, respectively. The debonding of polycrystalline brackets is caused by thermal softening of the bonding resin resulting from heating of the bracket. The hot bracket then slides off the tooth. All sapphire brackets debonded in less than 1 second. At sufficiently high power levels, debonding of sapphire brackets is caused by either thermal ablation or photoablation resulting from direct interaction of the light beam with the resin.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R M Tocchio
- Faculty of Dentistry, University of Manitoba, Canada
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27
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Shariati S, Pogrel MA, Marshall GW, White JM. Structural changes in dentin induced by high energy, continuous wave carbon dioxide laser. Lasers Surg Med Suppl 1993; 13:543-7. [PMID: 8264325 DOI: 10.1002/lsm.1900130508] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effect of a continuous wave carbon dioxide laser on dentin was observed as a function of power density and exposure time utilizing a wet scanning electron microscope. Visible charring occurred for all conditions studied. Surface cratering and flaking were followed by melting of the dentin. Melting resulted in a porous layer or porous globules of resolidified material and partial sealing of the tubules. Beneath the melted zone is an area of altered dentin where the tubules appear to be filled by solidification of the melted dentin.
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Affiliation(s)
- S Shariati
- Department of Oral Surgery, University of California, San Francisco 94143-0440
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28
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Arcoria CJ, Vitasek-Arcoria BA. The effects of low-level energy density Nd:YAG irradiation on calculus removal. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 1992; 10:343-7. [PMID: 10147966 DOI: 10.1089/clm.1992.10.343] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This study assessed the effects of using an Nd:YAG laser to remove dental calculus from root surfaces. Human extracted molar teeth, with extensive calculus attachment to root surfaces, were irradiated with an Nd:YAG beam [power densities (PD) = 1.09 W/cm 2 and 2.19 W/cm 2; energy densities (ED) = 49.2 J/cm 2 and 98.4 J/cm 2]. An additional group of teeth was instrumented with a Gracey 11/12 curette. A separate group of untreated specimens served as controls. Specimens were examined under scanning electron microscopy and rated as to the degree of calculus detachment from root surfaces. Nd:YAG irradiation at low ED did not appreciably affect the integrity of the calculus root surface attachment. The higher-ED Nd:YAG irradiation appeared to mimic the type of calculus removal depicted with conventional hand instrumentation. Root surface damage from both laser ablations was negligible.
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Affiliation(s)
- C J Arcoria
- Department of Restorative Sciences, Baylor College of Dentistry, Dallas, TX 75246
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29
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Abstract
The effect of a CO2 laser on the structure and permeability of smear layer-covered human dentin was evaluated in vitro. Three different energy levels were used (11, 113, and 566 J/cm2). The lowest exposure to the laser energy increased dentin permeability, measured as a hydraulic conductance, due to partial measured as a hydraulic conductance, due to partial loss of the superficial smear layer and smear plugs. The intermediate energy level also increased dentin permeability by crater formation, making the dentin thinner. The lack of uniform glazing of the surface of the crater, leaving its surface porous and in communication with the underlying dentinal tubules also contributed to the increase in dentin permeability seen with the intermediate laser energy. The highest laser energy produced complete glazing of the crater surfaces and sealed the dentinal tubules beneath the crater. However, it also completely removed the smear layer in a halo zone about 100-microns wide around each crater which increased the permeability of the pericrater dentin at the same time it decreased the permeability of the dentin within the crater. The combined use of scanning electron microscopy and permeability measurements provides important complementary information that is essential in evaluating the effects of lasers on dentin.
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Affiliation(s)
- E L Pashley
- School of Dentistry, Medical College of Georgia, Augusta
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30
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Melendez EJ, Arcoria CJ, Dewald JP, Wagner MJ. Effect of laser-etch on bond strengths of glass ionomers. J Prosthet Dent 1992; 67:307-12. [PMID: 1507090 DOI: 10.1016/0022-3913(92)90235-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This study evaluated the bond strength between glass ionomer cements and laser-etched dentin. Extracted human molars were sectioned sagittally, creating a flat surface. Samples were shear tested on an Instron testing machine, and mean bond strengths were recorded; statistical analyses indicated no significant differences between the Ketac cements. The bond strengths of both Ketac cements were significantly decreased when applied to laser-etched dentin, but bond strengths of Fuji-II were substantially elevated compared with the control values.
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31
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Arcoria CJ, Steele RE, Wagner MJ, Judy MM, Matthews JL, Hults DF. Enamel surface roughness and dental pulp response to coaxial carbon dioxide-neodymium: YAG laser irradiation. J Dent 1991; 19:85-91. [PMID: 1904890 DOI: 10.1016/0300-5712(91)90095-g] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The purpose of this study was to evaluate the effect of a coaxial carbon dioxide/neodymium:yttrium aluminium garnet laser beam on enamel surface roughness and the dental pulps of mongrel dogs. In four dogs, four maxillary left posterior teeth were irradiated at 16 cm source-tooth distances. Two teeth were irradiated with 16 W CO2/16 W Nd:YAG and the remaining two with 16 W CO2/40 W Nd:YAG. Two maxillary right teeth were untreated controls. In addition, mandibular premolars were irradiated at the same distance and power levels, extracted, and analysed for surface roughness. Significant differences in surface roughness were found between control samples and either power level, but not between enamel surfaces at the two power levels. Maxillary teeth were removed at 10 days postoperatively, sectioned and stained (H & E). The reaction of pulpal cells to irradiation was scored. Data analysis revealed statistically significant differences between the control and lower power Nd:YAG groups and between the control and higher power Nd:YAG groups. The difference in pulpal response between both laser groups approached significance.
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Affiliation(s)
- C J Arcoria
- Department of Operative Dentistry, Baylor College of Dentistry, Dallas, Texas
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32
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Jeffrey IW, Lawrenson B, Saunders EM, Longbottom C. Dentinal temperature transients caused by exposure to CO2 laser irradiation and possible pulpal damage. J Dent 1990; 18:31-6. [PMID: 2312887 DOI: 10.1016/0300-5712(90)90248-d] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
An investigation is described that attempts to establish, in vitro, the characteristics of heat transference following laser irradiation of bovine dentinal tissue and the relationship with the periodicity of radiation. The results of this study appear to indicate that at depths of overlying dentine of up to 3 mm, laser-induced thermal injury to the pulp is a definite possibility. Fail-safe facilities to prevent build up of heat must be incorporated into the design of dental lasers to allow their beneficial effects to be utilized without the risk of iatrogenic damage.
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Affiliation(s)
- I W Jeffrey
- Department of Conservative Dentistry, The University, Dundee, Scotland
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