1
|
Aggarwal P, Anand P, Singh K, Jhingan P, Malik M, Mathur S. Comparison of micromorphological changes in enamel using SEM analysis after conventional and erbium, chromium:yttrium, scandium, gallium, and garnet hard-tissue laser fissurotomy: An in vitro study. J Indian Soc Pedod Prev Dent 2023; 41:253-257. [PMID: 37861641 DOI: 10.4103/jisppd.jisppd_214_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2023] Open
Abstract
Background Well articulated by John Knowles - "Everything has to evolve or else it perishes." With the paradigm shift of emphasis toward the prevention of dental caries, it has been proven that laser irradiation protects against both caries initiation and caries progression. Aim The aim of the study was to evaluate and compare the micromorphology of caries-free extracted premolars using a Scanning electron microscope (SEM) after fissurotomy by conventional fissurotomy bur and erbium, chromium: yttrium, scandium, gallium, and garnet (ER, CR: YSGG) hard-tissue laser. Methodology Sixty caries-free premolars extracted atraumatically for orthodontic treatment were included in the study. The samples were divided into two groups randomly (Group 1: fissurotomy by bur, n = 30, and Group 2: fissurotomy by hard-tissue laser, n = 30). Each sample was further divided into halves from the occlusal surface wherein one-half of the occlusal surface received fissurotomy procedure and the other half was control. Samples were analyzed by scanning electron microscopy (SEM) for micromorphological changes. Results Profile image of control samples revealed the disorganization of enamel surface at the junction of fissures forming a heterogeneous tissue and agglomeration of enamel with deep pit and fissure. On the contrary, the image of experimented samples (with laser fissurotomy) showed smooth enamel surface and homogeneous enamel subsurface with wider pit and fissure owing to self-cleansing ability. Conclusion On the grounds of the present study results, it could be concluded that the intervention of ER, CR: YSGG hard-tissue laser possesses self-cleansable pit and fissures for caries prevention and has the potential to irradicate the smear layer entirely for superior attachment of remineralizing agents.
Collapse
Affiliation(s)
- Priyanka Aggarwal
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| | - Pallavi Anand
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| | - Kopal Singh
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| | - Pulkit Jhingan
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| | - Manvi Malik
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| | - Shivani Mathur
- Department of Pediatric and Preventive Dentistry, ITS-CDSR, Muradnagar, Uttar Pradesh, India
| |
Collapse
|
2
|
Evaluation of the Tooth Surface after Irradiation with Diode Laser Applied for Removal of Dental Microorganisms from Teeth of Patients with Gingivitis, Using X-ray Photoelectron (XPS) and Optical Profilometry (OP). J Clin Med 2022; 11:jcm11226840. [PMID: 36431317 PMCID: PMC9697199 DOI: 10.3390/jcm11226840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
Gingivitis is accompanied by microorganisms, including pathogens, which must be eliminated to speed up the treatment of inflammation. Laser irradiation may be one of the safe methods for reducing tissue contamination on the tooth surface. The aim of the study was the assessment of the tooth surface in patients with gingivitis after the use of a diode laser to eliminate microorganisms living there. In the first stage of the research, microorganisms were isolated (Candida albicans, C. guilliermondii, Escherichia coli, Haemophilus parainfluenzae, Klebsiella oxytoca, Neisseria subflava, Rothia dentocariosa, Rothia mucilaginosa, Streptococcus pneumoniae) from three patients with gingivitis, their identification confirmed using the MALDI-TOF MS technique (matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry). Then, the irradiation process with a diode laser was optimized to a wavelength of 810 nm ± 10 nm in five variants to reduce microorganisms on the tooth. The tooth surface was analyzed by X-ray photoelectron spectroscopy (XPS) and optical profilometry (OP) before and after irradiation. 103 to 106 CFU were detected on a 0.4 cm2 tooth area. Nine types of bacteria and two types of fungi dominated among the microorganisms. The laser at the most effective biocidal dose of 25 W/15.000 Hz/10 µs, average = 3.84 W, with three uses after 15 s, increased the reduction of fungi from 57.97% to 93.80%, and bacteria from 30.67% to 100%. This dose also caused a decrease in the degree of oxidation and in the effect of smoothing on the treated surfaces.
Collapse
|
3
|
Silva CV, Mantilla TF, Engel Y, Tavares JP, Freitas PM, Rechmann P. The effect of CO 2 9.3 μm short-pulsed laser irradiation in enamel erosion reduction with and without fluoride applications-a randomized, controlled in vitro study. Lasers Med Sci 2020; 35:1213-1222. [PMID: 32030555 DOI: 10.1007/s10103-020-02979-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 01/31/2020] [Indexed: 10/25/2022]
Abstract
The aim of this in vitro study was to evaluate the protective effect of short-pulsed CO2 9.3 μm laser irradiation against erosion in human enamel without and combined with TiF4 and AmF/NaF/SnCl2 applications, respectively, as well as compared to the protective effect of these fluoride treatments alone. After polishing, ninety enamel samples (3 × 3mm) were used for 9 different treatment groups: 4% TiF4 gel (pH 1.5, 24,533 ppm F-); AmF/NaF/SnCl2 rinse (pH 4.5; 500 ppm F-, 800 ppm Sn2); CO2 laser (average power 0.58 W); CO2 laser (0.58 W) + TiF4; CO2 laser (0.58 W) + AmF/NaF/SnCl2; CO2 laser (0.69 W); CO2 laser (0.69 W) + TiF4; CO2 laser (0.69 W) + AmF/NaF/SnCl2; negative control (deionized water). TiF4 gel was brushed on only once before the first erosive cycling, while samples treated with AmF/NaF/SnCl2 were daily immersed in 5 ml of the solution before cycling. Laser treatment occurred with a CO2 laser (wavelength 9.3 μm, pulse repetition rate 100 Hz, pulse duration 14.6 μs/18 μs, average power 0.58 W/0.69 W, fluence 1.9 J/cm2/2.2 J/cm2, beam diameter 0.63 mm, irradiation time 10 s, air cooling). TiF4 was applied only once, while AmF/NaF/SnCl2 was applied once daily before the erosive challenge. Surface loss (in μm) was measured with optical profilometry immediately after treatment, and after 5 and 10 days of erosive cycling (0.5% citric acid, pH 2.3, 6 × 2 min/day). Additionally, scanning electron microscopy investigations were performed. All application measures resulted in loss of surface height immediately after treatment. After 5 days, significantly reduced surface loss was observed after applying laser irradiation (both power settings) followed by applications of TiF4 or AmF/NaF/SnCl2 solution (p < 0.05; 2-way ANOVA and Tukey test) compared to fluoride application alone. After 10 days, compared to after 5 days, a reduced tissue loss was observed in all groups treated with AmF/NaF/SnCl2 solution. This tissue gain occurred with the AmF/NaF/SnCl2 application alone and was significantly higher when the application was combined with the laser use (p < 0.05). Short-pulsed CO2 9.3 μm laser irradiation followed by additional application of AmF/NaF/SnCl2 solution significantly reduces the progression of dental enamel erosion in vitro.
Collapse
Affiliation(s)
- C V Silva
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo (USP), Av Prof. Lineu Prestes, 2227 - Cidade Universitária, São Paulo, SP, 05508-000, Brazil
| | - T F Mantilla
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo (USP), Av Prof. Lineu Prestes, 2227 - Cidade Universitária, São Paulo, SP, 05508-000, Brazil
| | - Y Engel
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo (USP), Av Prof. Lineu Prestes, 2227 - Cidade Universitária, São Paulo, SP, 05508-000, Brazil
| | - J P Tavares
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo (USP), Av Prof. Lineu Prestes, 2227 - Cidade Universitária, São Paulo, SP, 05508-000, Brazil
| | - P M Freitas
- Department of Restorative Dentistry, Faculdade de Odontologia, Universidade de São Paulo (USP), Av Prof. Lineu Prestes, 2227 - Cidade Universitária, São Paulo, SP, 05508-000, Brazil
| | - P Rechmann
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California at San Francisco, 707 Parnassus Avenue, San Francisco, CA, 94143, USA.
| |
Collapse
|
4
|
Rechmann P, Le CQ, Kinsel R, Kerbage C, Rechmann BMT. In vitro CO 2 9.3-μm short-pulsed laser caries prevention-effects of a newly developed laser irradiation pattern. Lasers Med Sci 2020; 35:979-989. [PMID: 31897815 DOI: 10.1007/s10103-019-02940-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 12/22/2019] [Indexed: 11/24/2022]
Abstract
Caries prevention with different lasers has been investigated in laboratory studies and clinical pilot trials. Objective of this in vitro study was to assess whether 9.3-μm microsecond short-pulsed CO2 laser irradiation enhances enamel caries resistance without melting, with and without additional fluoride application. Seven groups of enamel, totaling 105 human enamel samples, were irradiated with 2 different carbon dioxide lasers with 2 different energy application systems (original versus spread beam; 9.3 μm wavelength, pulse repetition rate 43 Hz vs 100 Hz, fluence ranges from 1.4 to 3.9 J/cm2, pulse duration 3 μs to 18 μs). The laboratory pH-cycling was performed with or without additional fluoride, followed by cross-sectional microhardness testing. To assess caries inhibition, the mean relative mineral loss delta Z (∆Z) was determined. To evaluate for melting, scanning electron microscopy (SEM) examinations were performed. For the non-laser control groups with additional fluoride use, the relative mineral loss (ΔZ, vol% × μm) ranged between 512 ± 292 and 809 ± 297 (mean ± SD). ΔZ for the laser-irradiated samples with fluoride use ranged between 186 ± 214 and 374 ± 191, averaging a 58% ± 6% mineral loss reduction (ANOVA, P < 0.01 to P < 0.0001). For the non-laser-treated controls without additional fluoride, the mineral loss increased (ΔZ 914 ± 422 to 1224 ± 736). In contrast, the ΔZ for the laser-treated groups without additional fluoride ranged between 463 ± 190 and 594 ± 272 (P < 0.01 to P < 0.001) indicative of 50% ± 2% average reduction in mineral loss. Enhanced caries resistance was achieved by all applied fluences. Using the spread beam resulted in enhanced resistance without enamel melting as seen by SEM. CO2 9.3-μm short-pulsed laser irradiation with both laser beam configurations resulted in highly significant reduction in enamel mineral loss. Modifying the beam to a more homogenous profile will allow enamel caries resistance even without apparent enamel melting.
Collapse
Affiliation(s)
- Peter Rechmann
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California at San Francisco, 707 Parnassus Avenue, San Francisco, CA, 94143, USA.
| | - C Q Le
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California at San Francisco, 707 Parnassus Avenue, San Francisco, CA, 94143, USA
| | - R Kinsel
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California at San Francisco, 707 Parnassus Avenue, San Francisco, CA, 94143, USA
| | - C Kerbage
- Convergent Dental, 140 Kendrick Street, Bldg C3, Needham, MA, 02494, USA
| | - B M T Rechmann
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California at San Francisco, 707 Parnassus Avenue, San Francisco, CA, 94143, USA
| |
Collapse
|
5
|
Zancopé BR, Dainezi VB, Nobre-Dos-Santos M, Duarte S, Pardi V, Murata RM. Effects of CO 2 laser irradiation on matrix-rich biofilm development formation-an in vitro study. PeerJ 2016; 4:e2458. [PMID: 27833792 PMCID: PMC5101588 DOI: 10.7717/peerj.2458] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 08/17/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND A carbon dioxide (CO2) laser has been used to morphologically and chemically modify the dental enamel surface as well as to make it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of a CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM). METHODS For this in vitro study, 96 specimens of bovine enamel were employed, which were divided into two groups (n = 48): 1) Control-non-irradiated surface and 2) Irradiated enamel surface. Biofilms were grown on the enamel specimens by one, three and five days under intermittent cariogenic condition in the irradiated and non-irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and, in fifth day, were evaluated by polysaccharides analysis, quantitative real time Polymerase Chain Reaction (PCR) as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM). Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test. RESULTS The mean of log CFU/mL obtained for the one-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to the CO2 laser, CFU/mL and CFU/dry weight in three day was reduced significantly compared with control group. The difference in the genes expression (Glucosyltransferases (gtfB) and Glucan-binding protein (gbpB)) and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with the CO2 laser. Similar morphology was also visible with both treatments; however, the irradiated group revealed evidence of melting and fusion in the specimens. CONCLUSION In conclusion, CO2 laser irradiation modifies the energy surface and disrupts the initial biofilm formation.
Collapse
Affiliation(s)
- Bruna Raquel Zancopé
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP , Piracicaba, São Paulo , Brazil
| | - Vanessa B Dainezi
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP , Piracicaba, São Paulo , Brazil
| | - Marinês Nobre-Dos-Santos
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP , Piracicaba, São Paulo , Brazil
| | - Sillas Duarte
- Division of Restorative Sciences, Ostrow School of Dentistry of University of Southern California , Los Angeles, California , USA
| | - Vanessa Pardi
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Ostrow School of Dentistry of University of Southern California , Los Angeles, California , USA
| | - Ramiro M Murata
- Department of Foundational Sciences, School of Dental Medicine, East Carolina University , Greenville, North Carolina , USA
| |
Collapse
|
6
|
Rechmann P, Rechmann BMT, Groves WH, Le CQ, Rapozo-Hilo ML, Kinsel R, Featherstone JDB. Caries inhibition with a CO2 9.3 μm laser: An in vitro study. Lasers Surg Med 2016; 48:546-54. [PMID: 27075245 DOI: 10.1002/lsm.22497] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2016] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVES The caries preventive effects of different laser wavelengths have been studied in the laboratory as well as in pilot clinical trials. The objective of this in vitro study was to evaluate whether irradiation with a new 9.3 μm microsecond short-pulsed CO2 -laser could enhance enamel caries resistance with and without additional fluoride applications. STUDY DESIGN/MATERIALS AND METHODS One hundred and one human tooth enamel samples were divided into seven groups. Each group was treated with different laser parameters (CO2 -laser, wavelength 9.3 μm, 43 Hz pulse-repetition rate, pulse duration between 3 µs at 1.5 mJ/pulse to 7 µs at 2.9 mJ/pulse). A laboratory pH-cycling model followed by cross-sectional microhardness testing determined the mean relative mineral loss delta Z (ΔZ) for each group to assess caries inhibition in tooth enamel by the CO2 9.3 µm short-pulsed laser irradiation. The pH-cycling was performed with or without additional fluoride. RESULTS The non-laser control groups with additional fluoride had a relative mineral loss (ΔZ, vol% × µm) that ranged between 646 ± 215 and 773 ± 223 (mean ± SD). The laser irradiated and fluoride treated samples had a mean ΔZ ranging between 209 ± 133 and 403 ± 245 for an average 55% ± 9% reduction in mineral loss (ANOVA test, P < 0.0001). Increased mean mineral loss (ΔZ between 1166 ± 571 and 1339 ± 347) was found for the non-laser treated controls without additional fluoride. In contrast, the laser treated groups without additional fluoride showed a ΔZ between 470 ± 240 and 669 ± 209 (ANOVA test, P < 0.0001) representing an average 53% ± 11% reduction in mineral loss. Scanning electron microscopical assessment revealed that 3 µs pulses did not markedly change the enamel surface, while 7 µs pulses caused some enamel ablation. CONCLUSION The CO2 9.3 µm short-pulsed laser energy renders enamel caries resistant with and without additional fluoride use. The observed enhanced acid resistance occurred with the laser irradiation parameters used without obvious melting of the enamel surface as well as after irradiation with energies causing cutting of the enamel. Lasers Surg. Med. 48:546-554, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
Collapse
Affiliation(s)
- Peter Rechmann
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| | - Beate M T Rechmann
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| | - William H Groves
- Convergent Dental, Inc., 2 Vision Drive, Natick, Massachusetts, 01760
| | - Charles Q Le
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| | - Marcia L Rapozo-Hilo
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| | - Richard Kinsel
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| | - John D B Featherstone
- Department of Preventive and Restorative Dental Sciences, University of California at San Francisco, School of Dentistry, 707 Parnassus Avenue, San Francisco, California, 94143
| |
Collapse
|
7
|
Abstract
Direct pulp capping helps extend the life of a diseased tooth by maintaining tooth vitality. Nowadays, lasers are more frequently used during direct pulp capping in the clinic, but their use has not been previously reviewed. This review presents the basic properties of currently available lasers, scientific evidence on the effects of laser application on direct pulp capping, and future directions for this technology. An extensive literature search was conducted in various databases for articles published up to January 2015. Original in vitro, in vivo, and clinical studies, reviews, and book chapters published in English were included. Various laser systems have been increasingly and successfully applied in direct pulp capping. Lasers offer excellent characteristics in terms of hemostasis and decontamination for field preparation during direct pulp capping treatment; however, the sealing of exposed pulp with one of the dental materials, such as calcium hydroxide, mineral trioxide aggregates, and bonded composite resins, is still required after laser treatment. Clinicians should consider the characteristics of each wavelength, the emission mode, irradiation exposure time, power, type of laser tip, and the distance between the laser tip and the surface being irradiated.
Collapse
|
8
|
Lepri TP, Scatolin RS, Colucci V, De Alexandria AK, Maia LC, Turssi CP, Corona SAM. In Situanalysis of CO2laser irradiation on controlling progression of erosive lesions on dental enamel. Microsc Res Tech 2014; 77:586-93. [DOI: 10.1002/jemt.22377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/30/2014] [Accepted: 05/01/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Taísa Penazzo Lepri
- Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto; University of São Paulo (USP) Avenida do Café; S/N Monte Alegre CEP: 14040-904 Ribeirão Preto-SP Brazil
| | - Renata Siqueira Scatolin
- Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto; University of São Paulo (USP) Avenida do Café; S/N Monte Alegre CEP: 14040-904 Ribeirão Preto-SP Brazil
| | - Vivian Colucci
- Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto; University of São Paulo (USP) Avenida do Café; S/N Monte Alegre CEP: 14040-904 Ribeirão Preto-SP Brazil
| | - Adílis Kalina De Alexandria
- Department of Pediatric and Orthodontics, School of Dentistry; Federal University of Rio de Janeiro (UFRJ) Rua Prof.; Rodolpho Paulo Rocco 325 CEP 21941-913 Cidade Universitária-Rio de Janeiro-RJ Brazil
| | - Lucianne Cople Maia
- Department of Pediatric and Orthodontics, School of Dentistry; Federal University of Rio de Janeiro (UFRJ) Rua Prof.; Rodolpho Paulo Rocco 325 CEP 21941-913 Cidade Universitária-Rio de Janeiro-RJ Brazil
| | - Cecília Pedroso Turssi
- Department of Restorative Dentistry; São Leopoldo Mandic Institute and Dental Research Center; Av. José Rocha Junqueira, 13 CEP 13045-755 Campinas-SP Brazil
| | - Silmara Aparecida Milori Corona
- Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto; University of São Paulo (USP) Avenida do Café; S/N Monte Alegre CEP: 14040-904 Ribeirão Preto-SP Brazil
| |
Collapse
|
9
|
Lima DM, Tonetto MR, de Mendonça AAM, Elossais AA, Saad JRC, de Andrade MF, Pinto SCS, Bandéca MC. Human dental enamel and dentin structural effects after Er:YAG laser irradiation. J Contemp Dent Pract 2014; 15:283-7. [PMID: 25307807 DOI: 10.5005/jp-journals-10024-1529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
UNLABELLED Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations--namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and influence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifications caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. CLINICAL RELEVANCE Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the superficial structure of the target tissue irradiated, may be correlated to the structural optical modifications of the substrate produced by an interaction of the energy propagated by laser systems.
Collapse
Affiliation(s)
- Darlon Martíns Lima
- Professor, Postgraduation in Dentistry, Federal University of Maranhão São Luis, MA, Brazil
| | - Mateus Rodrigues Tonetto
- PhD Student, Department of Restorative Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil e-mail:
| | | | - André Afif Elossais
- PhD Student, Department of Restorative Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil
| | - José Roberto Cury Saad
- Professor, Department of Restorative Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil
| | | | | | - Matheus Coelho Bandéca
- Professor, Postgraduation in Dentistry, CEUMA University, São Luis, MA Collaborate Professor, University of Cuiabé, Cuiabé, MT, Brazil
| |
Collapse
|
10
|
Sabaeian M, Shahzadeh M. Simulation of temperature and thermally induced stress of human tooth under CO2 pulsed laser beams using finite element method. Lasers Med Sci 2013; 30:645-51. [PMID: 23868367 DOI: 10.1007/s10103-013-1390-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 07/08/2013] [Indexed: 12/13/2022]
Abstract
The authors report the simulation of temperature distribution and thermally induced stresses of human tooth under CO2 pulsed laser beam. A detailed tooth structure comprising enamel, dentin, and pulp with realistic shapes and thicknesses were considered, and a numerical method of finite element was adopted to solve time-dependent bio-heat and stress equations. The realistic boundary conditions of constant temperature for those parts embedded in the gingiva and heat flux condition for those parts out of the gingiva were applied. The results which were achieved as a function of energy density (J/cm(2)) showed when laser beam is irradiated downward (from the top of the tooth), the temperature and thermal stresses decrease quickly as a function of depth that is a result of strong absorption of CO2 beams by enamel. This effect is so influential that one can use CO2 beams to remove micrometer layers while underlying tissues, especially the pulp, are safe from thermal effects.
Collapse
Affiliation(s)
- Mohammad Sabaeian
- Physics Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran,
| | | |
Collapse
|
11
|
Ramalho KM, de Paula Eduardo C, Heussen N, Rocha RG, Lampert F, Apel C, Esteves-Oliveira M. Protective effect of CO2 laser (10.6 μm) and fluoride on enamel erosion in vitro. Lasers Med Sci 2012; 28:71-8. [DOI: 10.1007/s10103-012-1071-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 02/15/2012] [Indexed: 10/28/2022]
|
12
|
Prevention of toothbrushing abrasion of acid-softened enamel by CO(2) laser irradiation. J Dent 2011; 39:604-11. [PMID: 21741428 DOI: 10.1016/j.jdent.2011.06.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 06/15/2011] [Accepted: 06/16/2011] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE The aim of the present study was to evaluate the effect of CO(2) laser irradiation (10.6μm) at 0.3J/cm(2) (0.5μs; 226Hz) on the resistance of softened enamel to toothbrushing abrasion, in vitro. METHODS Sixty human enamel samples were obtained, polished with silicon carbide papers and randomly divided into five groups (n=12), receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C). After surface treatment they were submitted to a 25-day erosive-abrasive cycle in 100ml sprite light (90s) and brushed twice daily with an electric toothbrush. Between the demineralization periods samples were immersed in supersaturated mineral solution. At the end of the experiments enamel surface loss was determined using a contact profilometer and morphological analysis was performed using scanning electron microscopy (SEM). For SEM analysis of demineralization pattern, cross-sectional cuts of cycled samples were prepared. The data were statistically analysed by one-way ANOVA model with subsequent pairwise comparison of treatments. RESULTS Abrasive surface loss was significantly lower in all laser groups compared to both control and fluoride groups (p<0.0001 in all cases). Amongst the laser groups no significant difference was observed. Softened enamel layer underneath lesions was less pronounced in laser-irradiated samples. CONCLUSION Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5μs, 226Hz) either alone or in combination with amine fluoride gel significantly decreases toothbrushing abrasion of softened-enamel, in vitro.
Collapse
|
13
|
Esteves-Oliveira M, Pasaporti C, Heussen N, Eduardo C, Lampert F, Apel C. Rehardening of acid-softened enamel and prevention of enamel softening through CO2 laser irradiation. J Dent 2011; 39:414-21. [DOI: 10.1016/j.jdent.2011.03.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 03/09/2011] [Accepted: 03/20/2011] [Indexed: 11/28/2022] Open
|
14
|
A review of heat transfer in human tooth—Experimental characterization and mathematical modeling. Dent Mater 2010; 26:501-13. [DOI: 10.1016/j.dental.2010.02.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 01/04/2010] [Accepted: 02/23/2010] [Indexed: 12/28/2022]
|
15
|
Slutzky-Goldberg I, Peleg O, Liberman R, Stabholtz A, Moshonov J. The Effect of CO2Laser on the Microhardness of Human Dental Hard Tissues Compared with That of the High-Speed Drill. Photomed Laser Surg 2008; 26:65-8. [DOI: 10.1089/pho.2007.2059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Iris Slutzky-Goldberg
- Department of Endodontics, Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel
| | - Oren Peleg
- Department of Oral Surgery, Sheba Medical Center, Tel Hashomer, Israel
| | - Reuven Liberman
- Department of Oral Rehabilitation, The Maurice and Gabriella Goldsclegger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Adam Stabholtz
- Department of Endodontics, Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel
| | - Joshua Moshonov
- Department of Endodontics, Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel
| |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- A Vila Verde
- Department of Chemical Engineering, Fenske Laboratory, The Pennsylvania State University, University Park, PA 16802, USA
| | | | | |
Collapse
|
17
|
Fan K, Bell P, Fried D. Rapid and conservative ablation and modification of enamel, dentin, and alveolar bone using a high repetition rate transverse excited atmospheric pressure CO2 laser operating at lambda=9.3 micro. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:064008. [PMID: 17212531 DOI: 10.1117/1.2401151] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Transverse excited atmospheric pressure (TEA) CO(2) lasers tuned to the strong mineral absorption of hydroxyapatite near lambda=9 microm are well suited for the efficient ablation of dental hard tissues if the laser pulse is stretched to greater than 5 to 10 micros to avoid plasma shielding phenomena. Such CO(2) lasers are capable of operating at high repetition rates for the rapid removal of dental hard tissues. The purpose of this study was to test the hypothesis that stretched lambda=9.3-microA CO(2) laser pulses can produce lateral incisions in enamel, dentin, and alveolar bone for dental restorations and implants at repetition rates as high as 400 Hz without peripheral thermal damage. The single pulse ablation rates through enamel, dentin, and bone were determined for incident fluence ranging from (1 to 160 J/m(2)) for laser pulses from 5 to 18 mus in duration. Lateral incisions were produced in hard tissue samples using a computer-controlled scanning stage and water spray, and the crater morphology and chemical composition were measured using optical microscopy and high-resolution synchrotron radiation infrared spectromicroscopy. The residual energy remaining in tooth samples was measured to be 30 to 40% for enamel and 20 to 30% for dentin without water cooling, under optimum irradiation intensities, significantly lower than for longer CO(2) laser pulses. The transmission through 2-m length 300-, 500-, 750-, and 1000-microm silica hollow waveguides was measured and 80% transmission was achieved with 40 mJ per pulse. These results suggest that high repetition rate TEA CO(2) laser systems operating at lambda=9.3 microm with pulse durations of 10 to 20 micros are well suited for dental applications.
Collapse
Affiliation(s)
- Kenneth Fan
- University of California at San Francisco, Preventative & Restorative Dental Sciences, California 94143, USA
| | | | | |
Collapse
|
18
|
Klein ALL, Rodrigues LKA, Eduardo CP, Nobre dos Santos M, Cury JA. Caries inhibition around composite restorations by pulsed carbon dioxide laser application. Eur J Oral Sci 2005; 113:239-44. [PMID: 15953249 DOI: 10.1111/j.1600-0722.2005.00212.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This in vitro study aimed to evaluate whether laser irradiation of cavity margins reduces enamel demineralization around composite restoration. Enamel cavities were prepared in 33 human enamel slabs, which were randomly divided into three groups. One group was kept as a control, and the cavosurface margin of the cavities of the other groups were irradiated, using a CO(2) laser (lambda = 10.6 microm), at 8 J.cm(-2) or 16 J.cm(-2). The cavities were restored with a resin-based composite, according to the manufacturer's specifications. Before restoration, scanning electron microscopy was performed on one specimen of each group. The remaining slabs were submitted to thermal and pH-cycling models. Enamel mineral loss, at 50 and 100 microm from the restoration margin, was assessed by cross-sectional microhardness analyses. Fusion and melting were observed in the irradiated groups. Mineral loss at 50 microm from the restoration margin was significantly inhibited in the irradiated groups compared to the control group, but at 100 microm from the restoration margin, mineral loss at only the highest laser energy density differed statistically from the control group. The difference between the irradiated groups was not statistically significant at either 50 or 100 microm from the restoration margin. In conclusion, irradiation of the cavosurface margin of cavities, using a pulsed CO(2) laser, is able to inhibit enamel demineralization around composite restorations, and an energy density of 16 J.cm(-2) is efficient, even at 100 microm from the cavity margin.
Collapse
Affiliation(s)
- André L L Klein
- Faculty of Dentistry of Umuarama, University of Paraná, Umuarama, PR, Brazil
| | | | | | | | | |
Collapse
|
19
|
|
20
|
Ivanenko M, Werner M, Afilal S, Klasing M, Hering P. Ablation of hard bone tissue with pulsed CO2 lasers. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.mla.2005.02.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
21
|
Abstract
With the rapid development of laser technology, new lasers with a wide range of characteristics are now available and being used in various fields of dentistry. In the past two decades, much experience and knowledge has been gained. This article provides an overview of the current and possible future clinical applications of lasers in endodontics, including their use in alleviating dentinal hypersensitivity, modification of the dentin structure, pulp diagnosis, pulp capping and pulpotomy, cleaning and shaping of the root canal system, and endodontic surgery. Endodontic procedures for which conventional treatments cannot provide comparable results or are less effective are emphasized.
Collapse
Affiliation(s)
- Adam Stabholz
- Izador I Cabakoff Center for Advanced and Continuing Education in Dentistry, The Hebrew University-Hadassah School of Dental Medicine, P.O. Box 12272, Jerusalem 91120, Israel.
| | | | | |
Collapse
|
22
|
Rodrigues LKA, Nobre dos Santos M, Pereira D, Assaf AV, Pardi V. Carbon dioxide laser in dental caries prevention. J Dent 2004; 32:531-40. [PMID: 15304298 DOI: 10.1016/j.jdent.2004.04.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Revised: 03/25/2004] [Accepted: 04/06/2004] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVES To describe CO2 laser characteristics and to review the literature regarding its effects on caries inhibition in enamel and dentin. Another aim of this review is to discuss the effects of CO2 laser in combination with fluoride. DATA AND SOURCES The literature was searched for review and original research papers relating CO2 laser characteristics, CO2 laser effects on enamel and dentin, use of CO2 laser in dental caries prevention and the effects of CO2 laser in combination with fluoride. The articles have been selected using Medline and manual tracing of references cited in key papers otherwise not elicited. STUDY SELECTION Dental studies pertinent to key aspects of review, and those that focus on CO2 laser. CONCLUSIONS Irradiation of dental enamel by specific wavelengths and fluencies of CO2 laser alters the hydroxyapatite crystals reducing the acid reactivity of the mineral; CO2 laser irradiation in combination with fluoride treatment is more effective in inhibiting caries-like lesions than CO2 laser irradiation or fluoride alone; When laser and fluoride are combined, it is possible to reduce laser energy density and fluoride levels; If this laser technology becomes available at a reasonable cost and the results can be applied in clinical practice, there will be a promising future for this laser in caries prevention.
Collapse
|
23
|
Keller OR, Weber FE, Grätz KW, Baltensperger MM, Eyrich GK. Laser-induced temperature changes in dentine. ACTA ACUST UNITED AC 2004; 21:375-81. [PMID: 14709223 DOI: 10.1089/104454703322650194] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE The purpose of this work is to study the temperature rise and potential thermal damage caused during ablation of human dentine using a super pulsed carbon dioxide laser of 9.6-microm wavelength, equipped with a water-cooling spray and scanner system. BACKGROUND DATA There have been no reports on thermal effects of super pulsed CO2 laser of 9.6 microm wavelength on human dentine recently. MATERIALS AND METHODS Two different types of samples were investigated to yield data most consistent with a typical clinical situation. Human dentine slices and crown segments were studied at a drilling depth of 1.0 +/- 0.1 mm and 2.5 +/- 0.5 mm, respectively. A control group treated with a conventional hand piece was compared to four laser groups with settings varying from 2 to 8 W. RESULTS In the laser group demonstrating the highest elevation in temperature of the four studied, dentine slices lased at 2 W for 15 sec showed a mean temperature rise of less than 1.68 degrees C at an ablation rate of 0.86 +/- 0.08 mm. Conventional drilling with a comparable ablation rate of 0.76 +/- 0.59 mm resulted in a mean rise of 2.87 degrees C. The laser groups of crown segments revealed a constant decrease in temperature. SEM observations were lacking the typical morphological changes seen in earlier studies, specifically extensive melting, charring or cracking. CONCLUSION A maximum rise of mean temperature to 1.68 degrees C in closest vicinity to the pulpal chamber and the morphological unaltered dentine surfaces demonstrate the safe and tissue preserving character of the superpulsed 9.6 microm CO2 laser. The laser caused an even lower temperature rise than conventional drilling. Moreover, the laser showed acceptable efficacy with ablation rates that did not significantly differ from the conventional dental drill.
Collapse
Affiliation(s)
- O R Keller
- Department of Cranio-Maxillofacial Surgery, University Hospital Zurich, Zurich, Switzerland.
| | | | | | | | | |
Collapse
|
24
|
Fried D, Zuerlein MJ, Le CQ, Featherstone JDB. Thermal and chemical modification of dentin by 9-11-microm CO2 laser pulses of 5-100-micros duration. Lasers Surg Med 2003; 31:275-82. [PMID: 12355574 DOI: 10.1002/lsm.10100] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVES Previous studies have shown that dentin can be thermally modified by pulsed CO(2) laser irradiation to form a more highly mineralized tissue. The implications are important for the potential laser modification or removal of dentinal and root caries and the transformation of dentin to a more acid resistant mineralized tissue. STUDY DESIGN/MATERIALS AND METHODS Time resolved radiometry measurements with TEA CO(2) laser pulses were used to determine the magnitude of the absorption coefficients of dentin at the highly absorbed CO(2) laser wavelengths and to measure the temperature excursions during lambda = 9.3, 9.6, 10.3, and 10.6 microm laser irradiation at irradiation intensities of 0.1-8 J/cm(2) per pulse. In addition, photoacoustic and transient reflectance measurements were used to monitor the loss of water and organics and to detect the thresholds for surface modification and tissue ablation. RESULTS The absorption coefficients were measured to be 5,000; 6,500; 1,200; and 800 cm(-1) at lambda = 9.3, 9.6, 10.3, and 10.6 microm, respectively. The surface temperatures of dentin were markedly higher than those measured on enamel for similar irradiation intensities due to the lower reflectance losses of dentin and the lower thermal diffusivity of dentin at the respective wavelengths. Hence, lower fluences are required for the thermal decomposition of dentin. Ablation typically occurred with the first few laser-pulses during multiple pulse irradiation and eventually ceased after modification of dentin to a more highly mineralized enamel-like tissue. The debris ejected during the initial laser pulses shielded the surface by as much as 60% at the low fluences employed in this study. Optical and electron microscopy and IR spectroscopy indicated that incident laser pulses with incident fluence as low as 0.5 J/cm(2) at 9.3 and 9.6 microm wavelengths with a duration of 5-8-micros were sufficient to induce chemical and morphological changes in dentin. CONCLUSIONS In this study, the laser parameters for the efficient thermal modification of dentin with minimum heat deposition at CO(2) laser wavelengths were firmly established.
Collapse
Affiliation(s)
- Daniel Fried
- Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California 94143, USA.
| | | | | | | |
Collapse
|
25
|
Müllejans R, Eyrich G, Raab WHM, Frentzen M. Cavity preparation using a superpulsed 9.6-microm CO2 laser--a histological investigation. Lasers Surg Med 2002; 30:331-6. [PMID: 12116324 DOI: 10.1002/lsm.10063] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVES The superpulsed 9.6-microm CO(2) laser is an effective laser for ablating dental tissues and decay. This histological study compares laser class V preparations with conventional treatment to evaluate the resulting formation at the cavity walls. STUDY DESIGN/MATERIALS AND METHODS Four class V preparations (one made with a diamond drill and three with the CO(2) laser (9.6 microm, 60 microseconds pulse width, 40 mJ pulse energy, 100 Hz, integrated scanner system, water cooling) were performed on ten extracted teeth. The cavities were filled with a composite resin partly including enamel and dentine conditioning. RESULTS After laser preparation, no cracks or signs of carbonisation were detected. The results were comparable to those attained with conventional treatment. Following cavity filling without prior conditioning, gaps were noted at the cavosurface indicating a lack of adhesion. Dentinal bonding decreased gap formation significantly. CONCLUSION The 9.6-microm CO(2) laser is an effective tool for cavity preparation.
Collapse
Affiliation(s)
- R Müllejans
- Heinrich Heine University, Duesseldorf, Germany
| | | | | | | |
Collapse
|
26
|
Wigdor HA, Walsh JT. Histologic analysis of the effect on dental pulp of a 9.6-microm CO(2) laser. Lasers Surg Med 2002; 30:261-6. [PMID: 11948595 DOI: 10.1002/lsm.10051] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVE Both patients and dentists would like a replacement of the dental drill. During the last decade, lasers have been investigated as a possible replacement. For lasers to be accepted, studies must show that their effect on the dental pulpal tissues is equal to or less noxious than those effects caused by the dental handpiece (drill). STUDY DESIGN/MATERIALS AND METHODS In this study, two laser systems were used; the first was a breadboard CO(2) laser and the second a prototype clinical CO(2) laser system both emitted 60-micros-long pulses of 9.6-microm radiation. On the delivery system of both lasers, a scanner moved the focussed beam in a circular pattern and a water spray system served to cool the ablation site. Both lasers were used to create holes of similar dimensions in canine teeth. The treated teeth were then restored and harvested at either 4 days or 4 weeks. The teeth were decalcified, sectioned, and stained for examination via light microscopy. RESULTS The histologic examination revealed normal pulpal tissues in the canine teeth treated with both CO(2) lasers. Some histologic sections showed an increase in the predentin layer, 28 days after laser treatment. While many histologic sections showed normal pulpal architecture following handpiece treatment, some sections showed total disruption of the normal pulpal histology. CONCLUSIONS Histologic evaluation revealed that the lasers produced no noticeable damage to the dental pulpal tissue and appear to be a safe method for removing dental hard tissues. From this study, it appears that 9.6 microm CO(2) laser does not cause damage to the dental pulpal tissues in dogs.
Collapse
Affiliation(s)
- Harvey A Wigdor
- Department of Dentistry, Advocate-Ravenswood Hospital Medical Center, & Advocate-Illinois Masonic Medical Center, Chicago, Illinois 60640, USA.
| | | |
Collapse
|
27
|
Fried D, Ragadio J, Champion A. Residual heat deposition in dental enamel during IR laser ablation at 2.79, 2.94, 9.6, and 10.6 microm. Lasers Surg Med 2002; 29:221-9. [PMID: 11573223 DOI: 10.1002/lsm.1111] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVE The principal factor limiting the rate of laser ablation of dental hard tissue is the risk of excessive heat accumulation in the tooth. Excessive heat deposition or accumulation may result in unacceptable damage to the pulp. The objective of this study was to measure the residual heat deposition during the laser ablation of dental enamel at those IR laser wavelengths well suited for the removal of dental caries. Optimal laser ablation systems minimize the residual heat deposition in the tooth by efficiently transferring the deposited laser energy to kinetic and internal energy of ejected tissue components. STUDY DESIGN/MATERIALS AND METHODS The residual heat deposition in dental enamel was measured at laser wavelengths of 2.79, 2.94, 9.6, and 10.6 microm and pulse widths of 150 nsec -150 microsec using bovine block "calorimeters." Water droplets were applied to the surface before ablation with 150 microsec Er:YAG laser pulses to determine the influence of an optically thick water layer on reducing heat deposition. RESULTS The residual heat was at a minimum for fluences well above the ablation threshold where measured values ranged from 25-70% depending on pulse duration and wavelength for the systems investigated. The lowest values of the residual heat were measured for short (< 20 micros) CO(2) laser pulses at 9.6 microm and for Q-switched erbium laser pulses at 2.79 and 2.94 microm. Droplets of water applied to the surface before ablation significantly reduced the residual heat deposition during ablation with 150 microsec Er:YAG laser pulses. CONCLUSIONS Residual heat deposition can be markedly reduced by using CO(2) laser pulses of less than 20 microsec duration and shorter Q-switched Er:YAG and Er:YSGG laser pulses for enamel ablation.
Collapse
Affiliation(s)
- D Fried
- Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, California 94143, USA.
| | | | | |
Collapse
|
28
|
Fried NM, Fried D. Comparison of Er:YAG and 9.6-microm TE CO(2) lasers for ablation of skull tissue. Lasers Surg Med 2001; 28:335-43. [PMID: 11344514 DOI: 10.1002/lsm.1059] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVE Craniotomy by using a drill and saw frequently results in fragmentation of the skull plate. Lasers have the potential to remove the skull plate intact, simplifying the reconstructive surgery. STUDY DESIGN/MATERIALS AND METHODS Transverse-excited CO(2) lasers operating at the peak absorption wavelength of bone (lambda = 9.6 microm) and with pulse durations of 5-8 microsec, approximately the thermal relaxation time in hard tissue, produced high ablation rates and minimal peripheral thermal damage. Both thick (2 mm) and thin (250 microm) bovine skull samples were perforated and the ablation rates calculated. Results were compared with Q-switched and free-running Er:YAG lasers (lambda = 2.94 microm, tau(p) = 0.5 microsec and 300 microsec). RESULTS The CO(2) laser produced ablation rates of up to 60 and 15 microm per pulse for thin and thick sections, respectively, and perforated thin and thick sections with fluences of less than 1 J/cm(2) and 6 J/cm(2), respectively. There was no discernible thermal damage and no need for water irrigation during ablation. Pulse durations > or =20 microsec resulted in significant tissue charring, which increased with the pulse duration. Although the free-running Er:YAG laser produced ablation rates of up to 100 microm per pulse, fluences of 10 J/cm(2) and 30 J/cm(2) were required to perforate thin and thick samples, respectively, and peripheral thermal damage measured 25-40 microm. CONCLUSIONS In summary, the novel 5- to 8-microsec pulse length of the TE CO(2) laser is long enough to avoid a marked reduction in the ablation rate due to plasma formation and short enough to avoid peripheral thermal damage through thermal diffusion during the laser pulse. Furthermore, in vivo animal studies with the TE CO(2) laser are warranted for potential clinical application in craniotomy and craniofacial procedures.
Collapse
Affiliation(s)
- N M Fried
- Biomedical Engineering Department, Johns Hopkins University, Baltimore, Maryland 21205, USA.
| | | |
Collapse
|
29
|
Swift EJ, Edwards GS, Perdigão J, Thompson JY, Nunes MF, Ruddell DE, Negishi A. Free-electron laser etching of dental enamel. J Dent 2001; 29:347-53. [PMID: 11472807 DOI: 10.1016/s0300-5712(01)00019-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE The purpose of this study was to evaluate the Mark-III free-electron laser as a means of etching enamel surfaces, with potential application to resin bonding. METHODS The FEL was tuned to wavelengths ranging from 3.0 to 9.2 microm. Specific wavelengths that are resonantly absorbed by phosphates, proteins, and water were used. First, bovine enamel was polished and exposed to static FEL exposures. Lased enamel was examined using scanning electron microscopy (SEM). Additional bovine enamel specimens were exposed to FEL at similar wavelengths, but with rastering to create treated rectangular areas on each specimen. Surface roughness was evaluated using profilometry and atomic force microscopy (AFM). Composite was bonded to the lased enamel, and shear bond strengths were determined using an Instron universal testing machine. As a control, the surface roughness of, and shear bond strengths to, acid-etched enamel were determined. RESULTS Static FEL exposures caused changes in the enamel ranging from an etched appearance to pits, cracks, and frank cratering. The surface roughness of lased enamel was much greater than that of acid-etched enamel, and was qualitatively different as well. Shear bond strengths of resin to acid-etched enamel were significantly higher than bond strengths to lased enamel. CONCLUSIONS Under the conditions used in this study, the FEL did not offer a practical and effective method of etching enamel for resin bonding. However, the ability of the FEL to deliver many specific wavelengths makes it an interesting tool for further research of laser effects on tooth structure.
Collapse
Affiliation(s)
- E J Swift
- Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450, USA.
| | | | | | | | | | | | | |
Collapse
|
30
|
Fried D, Ragadio J, Akrivou M, Featherstone JD, Murray MW, Dickenson KM. Dental hard tissue modification and removal using sealed transverse excited atmospheric-pressure lasers operating at lambda=9.6 and 10.6 microm. JOURNAL OF BIOMEDICAL OPTICS 2001; 6:231-238. [PMID: 11375734 DOI: 10.1117/1.1344192] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2000] [Accepted: 11/08/2000] [Indexed: 05/23/2023]
Abstract
Pulsed CO(2) lasers have been shown to be effective for both removal and modification of dental hard tissue for the treatment of dental caries. In this study, sealed transverse excited atmospheric pressure (TEA) laser systems optimally tuned to the highly absorbed 9.6 microm wavelength were investigated for application on dental hard tissue. Conventional TEA lasers produce an initial high energy spike at the beginning of the laser pulse of submicrosecond duration followed by a long tail of about 1-4 micros. The pulse duration is well matched to the 1-2 micros thermal relaxation time of the deposited laser energy at 9.6 microm and effectively heats the enamel to the temperatures required for surface modification at absorbed fluences of less than 0.5 J/cm(2). Thus, the heat deposition in the tooth and the corresponding risk of pulpal necrosis from excessive heat accumulation is minimized. At higher fluences, the high peak power of the laser pulse rapidly initiates a plasma that markedly reduces the ablation rate and efficiency, severely limiting applicability for hard tissue ablation. By lengthening the laser pulse to reduce the energy distributed in the initial high energy spike, the plasma threshold can be raised sufficiently to increase the ablation rate by an order of magnitude. This results in a practical and efficient CO(2) laser system for caries ablation and surface modification.
Collapse
Affiliation(s)
- D Fried
- University of California, San Francisco, California 94143-0758, USA.
| | | | | | | | | | | |
Collapse
|
31
|
Featherstone JD, Fried D. Fundamental Interactions of Laserswith Dental Hard Tissues. ACTA ACUST UNITED AC 2001. [DOI: 10.1078/1615-1615-00022] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
32
|
Abstract
BACKGROUND AND OBJECTIVES Many studies of laser-induced thermal decomposition of dental enamel have demonstrated a reduction in the rate of acid dissolution, size of artificial caries-like lesions, and acid reactivity. Additionally, studies have correlated the loss of carbonate from dental enamel with a reduction in acid dissolution. Dental mineral consists of hydroxyapatite with many substitutions, the major one being carbonate ( approximately 3-5% by weight), which markedly affects acid reactivity. The principle objective of the present work was to determine the precise depth of modification, i.e. , thermally induced decomposition of dental enamel (carbonate loss), at the predicted optimum laser irradiation parameters. STUDY DESIGN/ MATERIALS AND METHODS: Bovine enamel blocks were irradiated at lambda = 9.6 microm with 2-microsec and 100-microsec pulses and at lambda = 10.6 microm with 2-microsec pulses. Carbonate loss was calculated from infrared spectra as a function of depth and compared to numerical simulations of the maximum temperature rise. RESULTS Carbonate loss was initiated at temperatures greater than 400 degrees C, but was complete only after repeated irradiation of the surface above the melting threshold. Carbonate loss of dental enamel irradiated at 9.6 microm with a 100-microsec pulse and at 10.6 microm with a 2-microsec pulse was greater than that of enamel irradiated at 9.6 microm with a 2-microsec pulse. The depth of carbonate loss in dental enamel irradiated with a 2-microsec pulse was greater for lambda = 10.6 microm than for lambda = 9.6 microm. CONCLUSION The depth of modification is consistent with the presented model that incorporates the absorption depth and thermal relaxation time/pulse duration. However, repeated irradiation is required for complete removal of carbonate, depending on absorption depth and pulse duration.
Collapse
Affiliation(s)
- M J Zuerlein
- Department of Restorative Dentistry, University of California at San Francisco, San Francisco, California 94143-0758, USA
| | | | | |
Collapse
|
33
|
Featherstone JD, Barrett-Vespone NA, Fried D, Kantorowitz Z, Seka W. CO2 laser inhibitor of artificial caries-like lesion progression in dental enamel. J Dent Res 1998; 77:1397-403. [PMID: 9649168 DOI: 10.1177/00220345980770060401] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Several studies during the last 30 years have demonstrated the potential of laser pre-treatment of enamel or tooth roots to inhibit subsequent acid-induced dissolution or artificial caries-like challenge in the laboratory. The overall objective of ongoing studies in our laboratories is to determine, systematically, the optimum sets of parameters for carbon dioxide laser irradiation that will potentially effectively inhibit dental caries in enamel and tooth roots. The aim of the present study was to examine the roles of wavelength and fluence in the prevention of caries progression in vitro in enamel by means of a pH-cycling model. The hypothesis to be tested was that the highly absorbed 9.3- and 9.6-microm wavelengths would be efficiently converted to heat, creating a temperature sufficiently high to reduce the acid-reactivity of the mineral and inhibit caries-like lesion progression in dental enamel. One hundred and sixty caries-free tooth crowns were cleaned and varnished with acid-resistant varnish, leaving one exposed window of enamel. Twelve groups of 10 enamel samples were irradiated in their individual windows by one of the four wavelengths (9.3, 9.6, 10.3, or 10.6 microm) of a tunable CO2 laser. Energy per pulse was 25, 50, 100, 200, or 250 mJ (25 pulses). Repetition rate was 10 Hz, and beam diameter was 1.6 mm. Fluence conditions of 1 to 12.5 J/cm2 per pulse were produced. All teeth, including 40 non-irradiated controls, were subjected to pH-cycling to produce artificial caries-like lesions. Results were assessed by cross-sectional microhardness testing. Inhibition of caries progression of from 40% to 85% was achieved over the range of laser conditions tested. At 9.3 and 9.6 microm, 25 pulses at absorbed fluences of 1 to 3 J/cm2 produced inhibition on the order of 70% with minimal subsurface temperature elevation (< 1 degree C at 2 mm depth), comparable with inhibition produced in this model with daily fluoride dentifrice treatments. Safety and efficacy studies will be required in animals and humans before these promising laboratory results can be applied in clinical practice.
Collapse
Affiliation(s)
- J D Featherstone
- Department of Restorative Dentistry, University of California at San Francisco, 94143-0758, USA
| | | | | | | | | |
Collapse
|