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Panahandeh N, Azarsina M, Ostad Hossein N, Fekrazad R. Microshear Bond Strength of Composite Resin to Enamel Treated With Titanium Tetrafluoride and the Carbon Dioxide Laser (10.6 µm): An In Vitro Study. J Lasers Med Sci 2021; 11:486-490. [PMID: 33425302 DOI: 10.34172/jlms.2020.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Introduction: The present study aims to assess the microshear bond strength (µSBS) of composite to enamel treated with titanium tetrafluoride (TiF4 ) and CO2 laser irradiation. Methods: Fifteen human molars were sectioned and their enamel surfaces were abraded. The sections were randomly assigned to 5 groups (n=15): (CO); control group, (AP); treated with 1.23% acidulated phosphate fluoride (APF) for 4 minutes, (Ti); 4% TiF4 for 1 minute, (L+AP); CO2 laser irradiation (10.6 µm wavelength, 1 W peak power, 10 ms pulse duration, 500 ms repetition time, 0.2 mm beam spot size at the tissue level, 2 cm distance of handpiece tip to tissue surface (DSE, South Cores) followed by 1.23% APF, and (L+ Ti); 10.6μm CO2 laser irradiation followed by 4% TiF4 for one minute. Using Tygon tubes, Z250 (3M/ESPE) composite was bonded to the surface of the samples. The µSBS of composite to enamel was measured using a microtensile testing machine after 500 thermal cycles. The data were analyzed by one-way ANOVA and the Tukey HSD test (P <0.05). Results: The mean µSBS was 20.66, 20.21, 13.44, 23.01, and 10.16 MPa in CO, AP, Ti, L+AP, and L+Ti groups respectively. Significant differences were observed between CO and Ti (P =0.026) and also CO and L+ Ti (P <0.0001). Conclusion: The application of TiF4 per se and after CO2 laser irradiation on enamel decreased the µSBS of composite to enamel; on the other hand, APF alone and after laser irradiation did not have any adverse effect on the µSBS of composite to enamel.
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Affiliation(s)
- Narges Panahandeh
- Associate Professor, Dental Research Center, Research Institute of Dental Sciences, Dental School, Shahid Beheshti University of Medical Sciences. Tehran, Iran
| | - Mohadese Azarsina
- Assistant Professor, Department of Operative Dentistry, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Reza Fekrazad
- Professor, Department of Periodontology, Dental Faculty - Laser Research Center in Medical Sciences, AJA University of Medical Sciences, Tehran, Iran
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Bahrololoomi Z, Poursina F, Birang R, Foroughi E, Yousefshahi H. The Effect of Er:YAG Laser on Entroccocus faecalis Bacterium in the Pulpectomy of Anterior Primary Teeth. J Lasers Med Sci 2017; 8:166-171. [PMID: 29071021 DOI: 10.15171/jlms.2017.30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Introduction: Successful root canal therapy depends on the complete elimination of microorganisms such as Entroccocus faecalis, which is impossible to achieve with the traditional methods. Lasers are recently introduced as a new method to solve the problem. The present study is planned and performed to examining the antibacterial effect of Er: YAG laser. Methods: Sixty extracted anterior primary teeth were prepared and sterilized. E. faecalis bacterium was cultured in canals. Samples were randomly divided into two groups. The first group was disinfected by NaOCl 5/25% and Er: YAG laser and the second group just by NaOCl 5/25%. Samples of canal contents were cultured and colony counts were calculated. The results were analyzed statistically by SPSS software and Mann Whitney test. Results: There was no significant difference between colony counts in both groups (P=0.142). But the number of colonies in the first group was lower than in the second group. Conclusion: Although, Er: YAG laser cannot completely eliminate E. faecalis bacterium, its simultaneous use with NaOCl decreases E. faecalis.
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Affiliation(s)
- Zahra Bahrololoomi
- Department of Pediatric Dentistry, Faculty of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Farkhondeh Poursina
- Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Reza Birang
- Periodontology Department, Dental Faculty, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Elnaz Foroughi
- Department of Pediatric Dentistry Faculty of Dentistry, Arak University of Medical Sciences, Arak, Iran
| | - Hazhir Yousefshahi
- Students Research Center, Dental Faculty, Isfahan University of Medical Sciences, Isfahan, Iran
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Corrêa-Afonso AM, Bachmann L, Almeida CGD, Corona SAM, Borsatto MC. FTIR and SEM analysis of CO2 laser irradiated human enamel. Arch Oral Biol 2012; 57:1153-8. [PMID: 22385837 DOI: 10.1016/j.archoralbio.2012.02.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 01/19/2012] [Accepted: 02/02/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Considering the enamel chemical structure, especially carbonate band, which has a major role in the caries prevention, the objective of the present study was to assess the chemical alterations on the enamel irradiated with CO(2) laser by means of FTIR spectroscopy and SEM analysis. DESIGN The enamel surfaces were analysed on a spectrometer for acquisition of the absorption spectrum relative to the chemical composition of the control sample. The irradiation was conducted with a 10.6-μm CO(2) laser (0.55W, 660W/cm(2)). The carbonate absorption band at 1600-1291cm(-1) as well as the water absorption band at 3793-2652cm(-1) was measured in each sample after the irradiation. The water band was measured again 24-h after the irradiation. The band area of each chemical compound was delimited, the background was subtracted, and the area under each band was integrated. Each area was normalized by the phosphate band (1190-702cm(-1)). RESULTS There was a statistically significant decrease (p<0.05) in the water content after irradiation (control: 0.184±0.04; irradiated: 0.078±0.026), which increased again after rehydration (0.145±0.038). The carbonate/phosphate ratio was measured initially (0.112±0.029) and its reduction after irradiation indicated the carbonate loss (0.088±0.014) (p<0.05). CONCLUSION The 10.6-μm CO(2) laser irradiation diminishes the carbonate and water contents in the enamel after irradiation.
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Affiliation(s)
- Alessandra Marques Corrêa-Afonso
- Departamento de Clínica Infantil, Odontologia Preventiva e Social, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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da Silva Tagliaferro EP, Rodrigues LKA, Soares LES, Martin AA, Nobre-dos-Santos M. Physical and Compositional Changes on Demineralized Primary Enamel Induced by CO2 Laser. Photomed Laser Surg 2009; 27:585-90. [DOI: 10.1089/pho.2008.2311] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | - Luís Eduardo Silva Soares
- Faculty of Dentistry, Dental Materials and Operative Dentistry Departments, UniVap, São José dos Campos, SP, Brazil
| | - Airton Abrahão Martin
- Laboratory of Biomedical Vibrational Spectroscopy, Research and Development Institute, IP&D, UniVap, São José dos Campos, SP, Brazil
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Staninec M, Darling CL, Goodis HE, Pierre D, Cox DP, Fan K, Larson M, Parisi R, Hsu D, Manesh SK, Ho C, Hosseini M, Fried D. Pulpal effects of enamel ablation with a microsecond pulsed lambda = 9.3-microm CO2 laser. Lasers Surg Med 2009; 41:256-63. [PMID: 19347946 PMCID: PMC3188421 DOI: 10.1002/lsm.20748] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVES In vitro studies have shown that CO2 lasers operating at the highly absorbed 9.3 and 9.6-microm wavelengths with a pulse duration in the range of 10-20-microsecond are well suited for the efficient ablation of enamel and dentin with minimal peripheral thermal damage. Even though these CO2 lasers are highly promising, they have yet to receive FDA approval. Clinical studies are necessary to determine if excessive heat deposition in the tooth may have any detrimental pulpal effects, particularly at higher ablative fluencies. The purpose of this study was to evaluate the pulpal safety of laser irradiation of tooth occlusal surfaces under the conditions required for small conservative preparations confined to enamel. STUDY DESIGN/MATERIALS AND METHODS Test subjects requiring removal of third molar teeth were recruited and teeth scheduled for extraction were irradiated using a pulsed CO2 laser at a wavelength of 9.3 microm operating at 25 or 50 Hz using a incident fluence of 20 J/cm(2) for a total of 3,000 laser pulses (36 J) for both rates with water cooling. Two control groups were used, one with no treatment and one with a small cut made with a conventional high-speed hand-piece. No anesthetic was used for any of the procedures and tooth vitality was evaluated prior to treatment by heat, cold and electrical testing. Short term effects were observed on teeth extracted within 72 hours after treatment and long term effects were observed on teeth extracted 90 days after treatment. The pulps of the teeth were fixed with formalin immediately after extraction and subjected to histological examination. Additionally, micro-thermocouple measurements were used to estimate the potential temperature rise in the pulp chamber of extracted teeth employing the same irradiation conditions used in vivo. RESULTS Pulpal thermocouple measurements showed the internal temperature rise in the tooth was within safe limits, 3.3+/-1.4 degrees C without water cooling versus 1.7+/-1.6 degrees C with water-cooling, n = 25, P<0.05. None of the control or treatment groups showed any deleterious effects on pulpal tissues and none of the 29 test-subjects felt pain or discomfort after the procedure. Only two test-subjects felt discomfort from "cold sensitivity" during the procedure caused by the water-spray. CONCLUSION It appears that this CO2 laser can ablate enamel safely without harming the pulp under the rate of energy deposition employed in this study.
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Affiliation(s)
- Michal Staninec
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Cynthia L. Darling
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Harold E. Goodis
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Daniel Pierre
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Darren P. Cox
- Department of Orofacial Sciences and Pathology, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Kenneth Fan
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Michael Larson
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Renaldo Parisi
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Dennis Hsu
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Saman K. Manesh
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Chi Ho
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Mehran Hosseini
- Department of Oral and Maxillofacial Surgery, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
| | - Daniel Fried
- Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758
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Rode AV, Gamaly EG, Luther-Davies B, Taylor BT, Graessel M, Dawes JM, Chan A, Lowe RM, Hannaford P. Precision ablation of dental enamel using a subpicosecond pulsed laser. Aust Dent J 2008; 48:233-9. [PMID: 14738125 DOI: 10.1111/j.1834-7819.2003.tb00036.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this study we report the use of ultra-short-pulsed near-infrared lasers for precision laser ablation of freshly extracted human teeth. The laser wavelength was approximately 800nm, with pulsewidths of 95 and 150fs, and pulse repetition rates of 1kHz. The laser beam was focused to an approximate diameter of 50microm and was scanned over the tooth surface. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain below 5 degrees C when the tooth was air-cooled during laser treatment. The surface preparation of the ablated teeth, observed by optical and electron microscopy, showed no apparent cracking or heat effects, and the hardness and Raman spectra of the laser-treated enamel were not distinguishable from those of native enamel. This study indicates the potential for ultra-short-pulsed lasers to effect precision ablation of dental enamel.
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Affiliation(s)
- A V Rode
- Research School of Physical Science and Engineering, Australian National University, Canberra, Australian Capital Territory
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Akca T, Yazici AR, Celik C, Ozgünaltay G, Dayangaç B. The effect of desensitizing treatments on the bond strength of resin composite to dentin mediated by a self-etching primer. Oper Dent 2007; 32:451-6. [PMID: 17910221 DOI: 10.2341/06-130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated the bond strength of resin composite to dentin, mediated by a self-etching adhesive, following the application of various dentin desensitizing treatments and artificial saliva storage. The buccal cervical areas of 24 extracted human third molars were ground flat to expose cervical dentin. The dentin surfaces were polished with 1200-grit SiC paper, then the teeth were randomly assigned to six groups, five desensitizing treatments and one control: Group I-VivaSens; Group II-Fluor Protector; Group III-Isodan; Group IV-Futura Bond NR; Group V-Nd:YAG laser and Group VI-Control (without application of a desensitizing agent). After applying the desensitizing treatments and storing the molars in artificial saliva for 14 days at 37 degrees C, Futura Bond NR was used to bond resin composite to dentin. TPH composite build-ups were constructed incrementally to a height of 5 mm. The teeth were sectioned to obtain bonded slices of 0.7 mm thick specimens containing the resin-composite joint. The specimens were then trimmed into an hourglass shape and subsequently subjected to microtensile testing at a crosshead speed of 1 mm/minute. The data were analyzed using the Kruskal-Wallis analysis and multiple comparisons test. The control (Group VI) and Futura Bond NR self-etching treatment (Group IV) group yielded statistically significant higher bond strength values than the other desensitizing treatment groups tested (p < 0.005). While pretreatment of dentin surfaces with desensitizing agents (Fluor Protector, VivaSens and Isodan) and laser (Nd:YAG) reduced the bond strength values of the resin composite, higher bond strengths were achieved using a self-etching adhesive (Futura Bond NR) as a desensitizing agent.
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Affiliation(s)
- Taner Akca
- Hacettepe University, Faculty of Dentistry, Department of Conservative Dentistry, Ankara, Turkey
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Sakae T, Sato Y, Numata Y, Suwa T, Hayakawa T, Suzuki K, Kuwada T, Hayakawa K, Hayakawa Y, Tanaka T, Sato I. Thermal ablation of FEL irradiation using gypsum as an indicator. Lasers Med Sci 2006; 22:15-20. [PMID: 17106786 DOI: 10.1007/s10103-006-0414-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Accepted: 09/20/2006] [Indexed: 12/01/2022]
Abstract
Thermal effects produced in a laser-irradiated sample were studied by micro-X-ray diffraction and micro-Fourier transform infrared spectroscopy (FTIR). Gypsum, transformed into bassanite at 124 degrees C and into anhydrite at 147 degrees C, was used as a thermal indicator. Pit formation by a wavelength-tunable free electron laser (FEL) irradiation on the gypsum pellet maximized at a wavelength of 3.0 microm, 2 mJ/shot, and pits were not detected in those irradiated at 2.6 or 3.8 microm compared with the maximum at 3.0 microm and diminished at 2.0 or 4.0 microm in the human tooth case. Micro-X-ray diffraction and micro-FTIR did not reveal any appreciable bassanite or anhydrite in the irradiated regions. From the laser ablation viewpoint, these results allow the FEL ablation to be considered as plasma or evaporative ones. This study indicated that the micro-pulse of laser was effective to prevent thermal damages of laser irradiation.
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Affiliation(s)
- Toshiro Sakae
- Department of Anatomy, Nihon University School of Dentistry, Matsudo, Chiba, 271-8587, Japan.
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Steiner-Oliveira C, Rodrigues LKA, Soares LES, Martin AA, Zezell DM, Nobre-dos-Santos M. Chemical, Morphological and Thermal Effects of 10.6-.MU.m CO2 Laser on the Inhibition of Enamel Demineralization. Dent Mater J 2006; 25:455-62. [PMID: 17076314 DOI: 10.4012/dmj.25.455] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Studies have shown that enamel can be modified by pulsed CO2 laser to form a more acid-resistant substrate. This study evaluated the effects of a 10.6-microm CO2 laser on enamel surface morphology and chemical composition as well as monitored intrapulpal temperature changes during irradiation. Human teeth were irradiated with fluences of 1.5-11.5 J/cm2, and pulpal thermal as well as chemical and morphological modifications on enamel were assessed. The teeth were submitted to a pH-cycling model, and the mineral loss was determined by means of cross-sectional microhardness. For all irradiated groups, intrapulpal temperature changes were below 3 degrees C. FT-Raman spectroscopy and scanning electron microscopy indicated that fluences as low as 6.0 J/cm2 were sufficient to induce chemical and morphological changes in enamel. Then, for fluences reaching or exceeding 10.0 J/cm2, laser-induced inhibitory effects on demineralization were observed. It was thus concluded that laser energy density in the range of 10.0 and 11.5 J/cm2 could be applied to dental enamel in order to produce chemical and morphological changes and reduce the acid reactivity of enamel without compromising the pulp vitality.
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Affiliation(s)
- Carolina Steiner-Oliveira
- Department of Pediatric Dentistry, Faculty of Dentistry of Piracicaba, State University of Campinas, São Paulo, Brazil
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Feuerstein O, Mayer I, Deutsch D. Physico-chemical changes of human enamel irradiated with ArF excimer laser. Lasers Surg Med 2005; 37:245-51. [PMID: 16175633 DOI: 10.1002/lsm.20224] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVES Irradiation of tooth enamel by lasers can alter its structure and chemical composition. The purpose of this work was to determine the compositional changes and to elucidate the mechanisms of laser-enamel interaction using ArF excimer laser. STUDY DESIGN/MATERIALS AND METHODS Human enamel irradiated with ArF excimer laser (wavelength, 193 nm) at different fluences, was examined using X-ray diffraction, infrared (IR) spectroscopy and microprobe analysis. RESULTS Ablation without significant compositional changes in irradiated enamel was evident when low fluences (approximately 200-380 mJ/cm2) were used. However, fluences between 640 and 2,300 mJ/cm2 resulted in an increased Ca/P ratio, decreased amount of carbonate and protein, and the formation of tricalcium phosphate and tetracalcium phosphate, suggesting the involvement of a photothermal mechanism. CONCLUSIONS The results show that ArF excimer laser can alter the chemical composition and morphology of the highly mineralized (96%) dental enamel, depending on the fluence used.
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Affiliation(s)
- Osnat Feuerstein
- Department of Prosthodontics, The Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel.
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Niccoli-Filho W, Penna LAP, Rode SM, Riva R. Effects of copper vapor laser irradiation (lambda = 510.6 nm) on the enamel and dentine of human teeth: an ultra-structural morphologic study. Photomed Laser Surg 2005; 22:494-8. [PMID: 15684749 DOI: 10.1089/pho.2004.22.494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE A morphological and ultra-structural study of copper vapor laser (lambda = 510.6 nm) effects on enamel and dentine was performed to show the effects of this radiation. METHODS A total of 15 human molars were cut in half; 15 pieces were separated for irradiation on enamel and 15 for dentine. These two groups were further divided into five experimental groups, including a control group, comprised of three half-sections each, irradiated by a CVL laser with a power of 7 W, a repetition rate of 15,000 pulses/sec and exposed at 500, 600, and 800 msec and 1 sec irradiation times with a 5-sec interval between irradiations. RESULTS In an ultra-structural SEM exam, we observed that on the enamel surfaces irradiated for 1 sec there was morphological alteration that consisted of catering, flaking, and melting on the surfaces. There was no alteration for the other exposure times. On the dentine teeth irradiated for 1 sec, we observed an evident ultra-structural alteration of melted tissue and loss of morphological characteristics. In the dentine group irradiated by 800 msec, we observed ablation and a partial loss of morphological characteristics. In the dentine groups irradiated by 500 and 600 msec, no alteration was observed. CONCLUSIONS The results showed that irradiation with CVL promoted morphologic changes in the enamel as well as in the dentine and demonstrated a need for future studies in order to establish a safe protocol for further use in the odontological practice.
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Affiliation(s)
- Walter Niccoli-Filho
- Academic Group Studies and Research with Lasers in Dentistry, Sao Paulo State University School of Dentistry, Sao Jose dos Campos, Sao Paulo, Brazil.
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Bachmann L, Craievich AF, Zezell DM. Crystalline structure of dental enamel after Ho:YLF laser irradiation. Arch Oral Biol 2004; 49:923-9. [PMID: 15353249 DOI: 10.1016/j.archoralbio.2004.05.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2004] [Indexed: 10/26/2022]
Abstract
Irradiation of teeth with lasers using specific wavelengths and energy densities produces surface melting. This effect has been already applied to different procedures such as caries prevention and hypersensitivity reduction. The aim of this study is to characterize the crystalline structure of bovine enamel after holmium laser irradiation. A holmium laser (Ho:YLF) with emission wavelength of 2065 nm was used. Enamel tissues were irradiated in ablative regime and their structures before and after irradiation were analyzed using the powder X-ray diffraction technique. The X-ray diffraction patterns of non-irradiated enamel correspond to carbonated hydroxyapatite and those produced by irradiated samples indicate the existence of a mixture of two crystalline phases: hydroxyapatite and tetracalcium phosphate. The structural characteristics of holmium irradiated enamel were compared with those of the same tissue irradiated with other lasers.
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Affiliation(s)
- Luciano Bachmann
- Centro de Lasers e Aplicações-CLA, Instituto de Pesquisas Energéticas e Nucleares-IPEN, Av. Lineu Prestes, 2242 Cidade Universitária, 05508-900 São Paulo-SP, Brazil.
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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.
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Hossain MMI, Hossain M, Kimura Y, Kinoshita JI, Yamada Y, Matsumoto K. Acquired acid resistance of enamel and dentin by CO2 laser irradiation with sodium fluoride solution. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 2002; 20:77-82. [PMID: 12017431 DOI: 10.1089/104454702753768052] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the caries-preventive effect of CO2 laser irradiation with or without sodium fluoride (NaF) solution at human dental enamel and dentin in vitro. BACKGROUND DATA The capability of caries prevention with CO2 laser irradiation has been reported in many previous studies, but few studies have been performed with regard to the combined effect of fluoride and laser. MATERIALS AND METHODS Forty extracted human incisor teeth were used for the enamel study, and 40 molar teeth were used for the dentin study. Samples were then divided into four categories: control (no treatment); CO2 laser irradiation only; NaF treatment only; and NaF treatment followed by CO2 laser irradiation. Each sample was immersed in 2 mL of lactic acid (0.1 M, pH 4.8) solution for 24 h at 37 degrees C in 100% humidity. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometry. The samples were also observed by stereoscopy and scanning electron microscopy (SEM). RESULTS The lowest mean Ca2+ ppm was recorded at the enamel or dentin samples treated with NaF and laser. Statistical analysis of the data was considered significant (p < 0.01). SEM observation showed that surfaces were changed to melted, smooth, and mirror-like appearances when CO2 laser irradiation was applied with NaF solution. CONCLUSION It can be concluded that CO2 laser irradiation with NaF solution has more caries-preventive effect than CO2 laser irradiation only at the enamel and dentin surfaces.
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Affiliation(s)
- M M Iqbal Hossain
- Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan
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Pelino JE, Mello JB, Eduardo CP, Jorge AO. In vitro study of the Nd:YAG laser effect on human dental enamel: optical and scanning electron microscope analysis. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 2001; 17:171-7. [PMID: 11199841 DOI: 10.1089/clm.1999.17.171] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The Nd:YAG laser irradiation of dental enamel was evaluated in enamel demineralization experiments in a Streptococcus mutans culture media. SUMMARY BACKGROUND DATA Previous studies had shown that a continuous wave Nd:YAG laser at an energy of approximately 67 mJ may induce an increased acid resistance in human dental enamel when exposed to severe demineralization conditions. METHODS Enamel windows of 3 x 4 cm in the buccal surface were irradiated with a continuous wave Nd:YAG laser at a wavelength of 1,064 microns using energy densities of from 83.75 to 187.50 J/cm2. Enamel windows of 3 x 4 cm on the lingual surface served as control (without the laser irradiation). The enamel windows were then exposed to a Streptococcus mutans culture media at a temperature of 37 degrees C for 15 and 21 days. The laser effects and demineralization were examined both by optical microscopy and scanning electron microscopy (SEM). RESULTS A comparison between the lased and the unlased windows of enamel showed fusion and recrystalization of the enamel and increased acid-resistance in all groups irradiated with the Nd:YAG laser. On the other hand, the 3 x 4 delimited enamel surfaces from the control group (not irradiated with the Nd:YAG laser) showed 100% demineralization. CONCLUSIONS These findings are consistent with the finding that laser irradiation of dental results in significant reduction of the effective solubility of enamel mineral.
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Affiliation(s)
- J E Pelino
- Department of Restorative Dentistry, UNESP, São José dos Campos, Brazil.
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16
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Kimura Y, Takahashi-Sakai K, Wilder-Smith P, Krasieva TB, Liaw LH, Matsumoto K. Morphological study of the effects of CO2 laser emitted at 9.3 microm on human dentin. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 2000; 18:197-202. [PMID: 11573511 DOI: 10.1089/10445470050144047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the effects of dentin ablation using a carbon dioxide (CO2) laser emitted at 9.3 microm by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). BACKGROUND DATA There have been no reports on effects of CO2 laser irradiation emitted at 9.3 microm on dentin by SEM and CLSM. METHODS Thirty extracted human teeth showing no clinical signs of caries were used. All teeth were horizontally sectioned to approximately 200 microm thickness and sections were irradiated using a 9.3 microm CO2 laser at different parameters as follows: 26 mJ [energy density (ED) 53.0 J/cm2] and 30 mJ (ED 61.1 J/cm2). After laser irradiation, samples were treated with sodium hypochlorite, stained using rhodamine-123, and observed with CLSM followed by SEM procedures. RESULTS No craters or cracks were observed, but many small molten and rehardened particles were documented on the sample surface using SEM. Some small cracks were seen in the subsurface layer, and some patent dentinal tubules were detected using CLSM. CONCLUSION These results suggest that laser irradiation at these parameters affected the sample surface only (less than 20 microm) and would be less harmful to thermal damage of dental pulp for dentin ablation.
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Affiliation(s)
- Y Kimura
- Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan.
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17
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Rohanizadeh R, LeGeros RZ, Fan D, Jean A, Daculsi G. Ultrastructural properties of laser-irradiated and heat-treated dentin. J Dent Res 1999; 78:1829-35. [PMID: 10598913 DOI: 10.1177/00220345990780121001] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted beta-tricalcium phosphate, beta-TCMP, beta-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950 degrees C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.
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Affiliation(s)
- R Rohanizadeh
- Laboratoire de recherche sur les tissus calcifiés et les biomatériaux, Faculté de Chirurgie Dentaire, Nantes, France
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18
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Abstract
In this study, the cutting ability of a newly developed dental laser was compared with a dental high-speed handpiece and rotary bur for removal of enamel. Measurements of the volume of tissue removed, energy emitted, and time of exposure were used to quantify the ablation rate (rate of tissue removal) for each test group and compared. Cutting efficiency (mm3/s) of the laser was calculated based on the mean volume of tissue removed per pulse (mm3/pulse) and unit energy expended (mm3/J) over the range of applied powers (2, 4, 6, and 8 W). The specimens were then examined by light microscopy and scanning electron micrographs for qualitative analysis of the amount of remaining debris and the presence of the smear layer on the prepared enamel surface. Calculations of the cutting efficiency of the laser over the range of powers tested revealed a linear relationship with the level of applied power. The maximum average rate of tissue removal by the laser was 0.256 mm3/s at 8 W, compared with 0.945 mm3/s by the dental handpiece. Light microscopy and scanning electron micrograph examinations revealed a reduction in the amount of remaining debris and smear layer in the laser-prepared enamel surfaces, compared with the conventional method. Based on the results of this study, the cutting efficiency of the high-speed handpiece and dental bur was 3.7 times greater than the laser over the range of powers tested, but the laser appeared to create a cleaner enamel surface with minimal thermal damage. Further modifications of the laser system are suggested for improvement of laser cutting efficiency.
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Affiliation(s)
- G Levy
- Department of Endodontics, School of Dentistry, University of Marseilles, France
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19
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Corpas-Pastor L, Villalba Moreno J, de Dios Lopez-Gonzalez Garrido J, Pedraza Muriel V, Moore K, Elias A. Comparing the tensile strength of brackets adhered to laser-etched enamel vs. acid-etched enamel. J Am Dent Assoc 1997; 128:732-7. [PMID: 9188230 DOI: 10.14219/jada.archive.1997.0296] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This study compared the tensile bond strength of brackets adhered to laser-etched enamel with that of brackets adhered to acid-etched enamel. Forty extracted, intact bovine teeth were treated with either 37 percent phosphoric acid for 15 seconds or neodymium:yttrium-aluminumgarnet laser on black-ink-coated enamel. After thermocycling, tensile stress was applied to the bonded specimens at a 0.1 millimeter/minute orosshead speed. A t-test comparison of means showed a significant difference between the laser-etched and acid-etched teeth, with the acid-etched teeth demonstrating significantly more tensile bond strength at a 95 percent level of significance.
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20
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Spencer P, Cobb CM, McCollum MH, Wieliczka DM. The effects of CO2 laser and Nd:YAG with and without water/air surface cooling on tooth root structure: correlation between FTIR spectroscopy and histology. J Periodontal Res 1996; 31:453-62. [PMID: 8915947 DOI: 10.1111/j.1600-0765.1996.tb01409.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Morphologic and chemical characterization of root surfaces treated with either the CO2 laser, Nd:YAG, or Nd:YAG with water/air surface cooling (Nd:YAG-C) was completed using scanning electron microscopy (SEM) and FTIR photoacoustic spectroscopy (FTIR/PAS). Specimens for morphologic analysis consisted of 20 extracted single rooted teeth unaffected by periodontal disease. The specimens were exposed at varying energy densities to a single pass of the laser. SEM examination revealed, for all lasers, a direct correlation between increasing energy densities and depth of tissue ablation and width of tissue damage. The Nd:YAG-C required higher energy densities than either the CO2 or Nd:YAG lasers to achieve the same relative depth of tissue ablation. Regardless of energy density, and in contrast with other laser types, areas treated with the Nd:YAG-C did not exhibit collateral zones of heat damage. Specimens for spectroscopic examination consisted of 12 disks, 6 x 2 mm, cut from debrided root surfaces of extracted, unerupted human molars. The spectral results indicate a substantial reduction in the absorption bands attributable to protein and an additional band at 2015 cm-1 in specimens exposed to the Nd:YAG without water. In the presence of water/air coolant, the band at 2015 cm-1 appears only at a substanially higher energy density. The spectra of the CO2 treated specimens, with the char layer present, show a significant reduction in the protein bands and additional bands at 2015 and 2200 cm-1, that are tentatively assigned to the cyanamide and cyanate ions, respectively. These results suggest a reaction of the organic matrix and mineral with laser exposure.
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Affiliation(s)
- P Spencer
- University of Missouri-Kansas City School of Dentistry, Department of Oral Biology 64108, USA
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21
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Kinney JH, Haupt DL, Balooch M, White JM, Bell WL, Marshall SJ, Marshall GW. The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces. J Dent Res 1996; 75:1388-95. [PMID: 8831634 DOI: 10.1177/00220345960750061001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.
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Affiliation(s)
- J H Kinney
- Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, California 94551, USA
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22
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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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23
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Silberman JJ, Dederich DN, Vargas M, Denehy GE. SEM comparison of acid-etched, CO2 laser-irradiated, and combined treatment on dentin surfaces. Lasers Surg Med Suppl 1994; 15:269-76. [PMID: 7830472 DOI: 10.1002/lsm.1900150306] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Research into polymer systems capable of bonding to dentin and enamel have resulted in improved bond strengths that allow more conservative restoration and strengthening of teeth. However, pretreatment of the dentin and enamel of various sorts, including exposure to laser energy, have been espoused to enhance this bonding. This study investigated the effects of two pretreatments, acid and CO2 laser exposure, both alone and in combination, on the surface topography of prepared dentin specimens as observed by scanning electron microscopy. Eighteen dentin specimens were flat-sanded with 600 grit sandpaper and exposed to 10% maleic acid and CO2 laser both alone and in combination. SEM observation suggested that laser treatment prior to acid etching could increase the resistance of the smear layer to acid removal, that laser exposure after acid treatment could expose a porous topography suggestive of the underlying dentin inorganic structure by way of vaporization of the collagen surface left after acid demineralization, and that these effects varied in degree with the laser exposure energy.
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Affiliation(s)
- J J Silberman
- Department of Operative Dentistry, College of Dentistry, University of Iowa, Iowa City 52242
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24
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McKee MD. Effects of CO2 laser irradiation in vivo on rat alveolar bone and incisor enamel, dentin, and pulp. J Dent Res 1993; 72:1406-17. [PMID: 8408883 DOI: 10.1177/00220345930720101001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Previous studies have shown that a surgical 'window' can be drilled in alveolar bone for experimental manipulation of the underlying enamel organ and enamel. To determine whether similar and/or improved access could be obtained by use of the surgical capabilities of laser optics, and to note the effects of laser irradiation in vivo on the extracellular matrices and cells of bone, enamel, and dentin, tissue responses to laser-created lesions were examined histologically. Briefly, samples were prepared in which the alveolar bone along the inferior mandibular border of Wistar rats was exposed, and a continuous-wave CO2 laser equipped with a custom-made micromanipulator was used to penetrate the bone and to create lesions within the lower incisor. Animals were perfusion-fixed at either 10 min or 10 days post-treatment, and affected tissues were processed for light and transmission electron microscopy. At 10 min, all lesions consisted of a void of ablated tissue containing some organic debris. Tissues immediately surrounding the lesion were generally intact, but showed some damage, presumably resulting from elevated temperature effects. At 10 days, lesions in the bone, dentin, odontoblast layer, or pulp showed morphological evidence of tissue repair represented by the presence of cell infiltrates, new bone, or reparative dentin. In lesions that were created during the secretory stage of amelogenesis that had moved into the maturation stage, there was evidence of delayed or incomplete maturation of enamel (i.e., retention of organic matrix normally lost during maturation) related to the enamel organ affected by the laser treatment. In the bone lesion at 10 days, new bone formation was observed, while bone fragments originally created at the time of lasing were surrounded by mononuclear and large multinucleated giant cells. It is thus concluded that the application of this laser system is an alternative method for exposing unerupted dental tissues for experimental manipulation, and that laser irradiation may also be useful for the study of mineralized tissue repair.
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Affiliation(s)
- M D McKee
- Department of Stomatology, Faculty of Dentistry, Université de Montréal, Québec, Canada
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25
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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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26
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White JM, Goodis HE, Setcos JC, Eakle S, Hulscher BE, Rose CL. Effects of pulsed Nd:YAG laser energy on human teeth: a three-year follow-up study. J Am Dent Assoc 1993; 124:45-51. [PMID: 8335798 DOI: 10.14219/jada.archive.1993.0273] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study of laser use on dental hard tissues evaluated restorations and tooth vitality in teeth treated three years earlier. All teeth remained vital and asymptomatic. Restorations placed after caries removal were intact and clinically serviceable.
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Affiliation(s)
- J M White
- Department of Restorative Dentistry, University of California, School of Dentistry, San Francisco 94143-0758
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27
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Feuerstein O, Palanker D, Fuxbrunner A, Lewis A, Deutsch D. Effect of the ArF excimer laser on human enamel. Lasers Surg Med Suppl 1992; 12:471-7. [PMID: 1405998 DOI: 10.1002/lsm.1900120503] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Human enamel surface was irradiated with ArF excimer laser and examined under light microscopy and scanning electron microscopy (SEM). Enamel surface was irradiated at three different areas with different energy fluences. It is demonstrated that the ArF excimer laser causes ablation of the calcified hard enamel tissue. Ablation curves were measured. There was no significant difference found in the etch depth between the three different areas of enamel surface. The morphology of the irradiated areas seen under the SEM was found to be dependent on energy fluence. It changed with increase in energy fluence from being etched to forming a smooth, fused, glaze-like surface and then at very high energy fluences producing a rough surface. The influence of the laser irradiation was confined to the irradiated area only, with no visible heat damage to the surroundings. These results suggest that excimer laser could be applied in a controlled and defined manner for tooth enamel treatments in dentistry.
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Affiliation(s)
- O Feuerstein
- Dental Research Unit, Hebrew University-Hadassah Faculty of Dental Medicine, Jerusalem, Israel
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28
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Abstract
Lasers have been proposed for numerous dental applications. Research on laser irradiation of enamel has demonstrated structural changes that resulted in a decrease in acid dissolution of the enamel. Dentin irradiation produced changes in surface morphology that improved bonding of restorative resins. This article reviews the studies of the effects of laser irradiation on oral tissues.
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Affiliation(s)
- M L Myers
- Medical College of Georgia, School of Dentistry, Augusta
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29
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Wong J, Otsuka M, Higuchi WI, Powell GL, Fox JL. Effect of laser irradiation on the dissolution kinetics of hydroxyapatite preparations. J Pharm Sci 1990; 79:510-5. [PMID: 2395094 DOI: 10.1002/jps.2600790611] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This research investigated the effects of a laser irradiation treatment on the dissolution characteristics of hydroxyapatite (HAP), and the results provide an insight into the relationship between the effects of laser treatment and the two-site dissolution kinetics of HAP samples. The HAP samples prepared by aqueous precipitation and digestion at approximately 100 degrees C were irradiated with a CO2 laser (20-50 W) with a beam diameter of 14 mm for a total of 10-400 s. Dissolution rates of the laser-treated HAP samples were subsequently determined in acetate buffer (pH = 4.5, mu = 0.50) at various levels of partial saturation (0-24% with respect to the HAP thermodynamic solubility of pKsp = 116). The following were the important findings. The X-ray diffraction and the IR spectroscopy results suggested that the HAP crystalline structure was not changed by laser treatment. Laser treatment of HAP powder at 50 W for 400 s, however, caused an approximately 3.5-fold reduction in the specific surface area of HAP and reduced the initial dissolution rate of HAP in acetate buffer by a factor of approximately 22.9. Also, this laser treatment appeared to reduce the dissolution rate of HAP in 16 and 24% partially saturated acetate buffer from substantial levels to essentially zero. These results may be summarized as follows. Laser treatment of HAP results in a reduction in the dissolution rate and also a reduction in the specific surface area of this material. However, the dissolution rate reduction is significantly greater than the reduction in the specific surface area.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Wong
- Department of Pharmaceutics, University of Utah, Salt Lake City 84112
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30
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Jeffrey IW, Lawrenson B, Longbottom C, Saunders EM. CO2 laser application to the mineralized dental tissues--the possibility of iatrogenic sequelae. J Dent 1990; 18:24-30. [PMID: 2107231 DOI: 10.1016/0300-5712(90)90247-c] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
From the many types of laser that are available commercially, the CO2 laser is presently thought to have the greatest potential for use in dentistry. An outline of the generation of emitted radiation from such a laser is given together with a review of work previously carried out and reported in the literature regarding application to the teeth. The main points of interest are the effects of radiation on the enamel and dentine, but concern is felt towards the possible iatrogenic damage of thermal origin that may occur within the pulp following irradiation of the dental tissues.
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Affiliation(s)
- I W Jeffrey
- Department of Conservative Dentistry, The University, Dundee, Scotland
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31
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Ferreira JM, Palamara J, Phakey PP, Rachinger WA, Orams HJ. Effects of continuous-wave CO2 laser on the ultrastructure of human dental enamel. Arch Oral Biol 1989; 34:551-62. [PMID: 2512902 DOI: 10.1016/0003-9969(89)90094-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Laser-induced changes in plano-parallel sections were examined by light microscopy (LM) and scanning electron microscopy (SEM), and correlated with ultrastructural changes as observed by transmission electron microscopy (TEM). LM and SEM revealed two different changes--extensive crazing, and crazing and cratering. Rough exposed enamel was commonly found, resulting from lifting off and removal of the top layer of crazed, or crazed and cratered, enamel. The type of induced change was mainly dependent on the energy density used (range approximately 0.8 to approximately 200 J cm-2) and on enamel prism orientation. Lased enamel was also softer than unlased enamel. TEM of both crazed enamel and rough exposed enamel revealed that most crystals generally resembled those of unlased enamel in size and shape, but that inter- and intra-crystalline voids were present in some areas. The crazed and cratered enamel had significant ultrastructural changes: new homogeneous and inhomogeneous crystals of apatite with a different shape and larger size than those of the original, and a loss of prismatic structure. The lack of uniformity of the laser effect on crazed and cratered enamel was shown by variation in crystal packing (from good to poor), variations in crystal size from area to area, and the presence of pockets of poorly packed homogeneous crystals alongside pockets of well-packed inhomogeneous crystals. The crazing, crazing and cratering, rough exposed enamel and the greater number of voids, as well as the relative softness of lased enamel do not indicate an overall ultrastructural improvement. However, the larger apatite crystal size and loss of prismatic structure in crazed and cratered areas may partly explain previous observations of reduced rates of subsurface demineralization in lased enamel.
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Affiliation(s)
- J M Ferreira
- Department of Physics, Monash University, Clayton, Victoria, Australia
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32
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Abstract
The use of lasers in dentistry has been considered for over 20 years. Higher-energy density lasers were shown to fuse enamel but were potentially unsafe. Subsequently, low-energy density laser radiation was shown to affect artificial caries lesion formation. Recent studies have shown that carbon dioxide lasers can successfully be used at low-energy densities to fuse enamel, dentin, and apatite. Our studies have shown that specific wavelengths are highly efficient. These wavelengths are directly related to the infrared absorption regions of apatite. We have conducted studies with enamel and dentin, using pulsed CO2 laser radiation in the 9.32-μm to 10.49-μm region with energy densities in the 10 to 50 J.cm-2 range. This laser treatment caused surface fusion and inhibition of subsequent lesion progression and markedly improved the bonding strength of a composite resin to dentin. Similar studies have shown no pulpal damage or permanent deleterious effect on soft tissues. This improved understanding of the scientific rationale for the interaction of CO2 lasers with teeth can lead to several clinical applications. This will depend, however, on the development of a technology to direct a specific frequency laser beam precisely to a desired site.
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33
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Fowler BO, Kuroda S. Changes in heated and in laser-irradiated human tooth enamel and their probable effects on solubility. Calcif Tissue Int 1986; 38:197-208. [PMID: 3011230 DOI: 10.1007/bf02556711] [Citation(s) in RCA: 249] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Enamel of intact human teeth laser irradiated in vitro under certain conditions is known to have less subsurface demineralization than unirradiated enamel on exposure to acid; consequently, the potential use of laser irradiance to reduce caries is apparent. The laser-induced physical and/or chemical changes that cause this reduced subsurface demineralization are not known. A laser-irradiated tooth enamel surface will have a temperature gradient that decreases towards the dentin junction. Dependent on irradiant conditions, the temperature may range from greater than 1400 degrees C at the surface to near normal at the dentin-pulp junction. Along this steep temperature gradient, different compositional, structural, and phase changes in the tooth enamel are to be expected. Identification of changes occurring along this gradient has bearing on understanding the dissolution reduction mechanism and, in turn, optimizing its effect. Changes in laser-irradiated material from the highest temperature region have been characterized, but those occurring in sequential layers of decreasing temperatures have not. Since the laser-induced changes are expected to primarily arise from localized heating, previously reported thermally induced changes in tooth enamel on heating in conventional furnaces were utilized to infer corollary changes along the gradient in laser-irradiated tooth enamel. These thermally inferred changes which resulted in modifications in the tooth enamel apatite and/or newly formed phases were correlated with their probable effects on altering solubility. A temperature gradient range from 100-1600 degrees C was considered with subdivisions as follows: I, 100-650 degrees C; II, 650-1100 degrees C; and III, greater than 1100 degrees C. Two of the products formed in range III, alpha-Ca3(PO4)2 and Ca4(PO4)2O, and also identified in the fused-melted material from laser-irradiated tooth enamel, are expected to markedly increase solubility in those regions that contain considerable amounts of these compounds. Products and changes occurring in range II, separate phases of alpha- and/or beta-Ca3(PO4)2 and a modified phase of apatite, may increase or decrease the solubility depending on the Ca/P ratio and the resultant amounts of alpha-, beta-Ca3(PO4)2 formed. Modifications in tooth enamel apatite effected in range I are expected to decrease its solubility; the formation of pyrophosphate in this range may have a substantial effect on reducing the solubility rate.(ABSTRACT TRUNCATED AT 400 WORDS)
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Kuroda S, Fowler BO. Compositional, structural, and phase changes in in vitro laser-irradiated human tooth enamel. Calcif Tissue Int 1984; 36:361-9. [PMID: 6435835 DOI: 10.1007/bf02405347] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Tooth enamel laser irradiated under certain conditions previously has been shown to have reduced subsurface demineralization rates. Identification of these laser-induced changes has bearing on understanding the dissolution rate reduction mechanism; some of these changes, ones that occur in high temperature regions, were studied in this report. X-ray diffraction and infrared spectroscopy were used to identify changes in enamel of extracted intact human teeth subjected to high energy density (approximately 10,000 J/cm2) 10.6 microns wavelength carbon dioxide laser irradiance. The laser irradiance melted the enamel apatite; this solidified melt was composed of minor phases of alpha-tricalcium phosphate, alpha-Ca3 (PO4)2, and tetracalcium phosphate, Ca4(PO4)2O, and a major phase of modified apatite. The apatite modifications, as compared with the original were (1) reductions in contents of water, protein, carbonate, and chloride (or chloride rearrangement); (2) essentially no change in apatite hydroxide content; (3) possible incorporation of oxide replacing some hydroxide ions; and (4) an uptake of traces of carbon dioxide and cyanate. An infrared band at 434 cm-1 that appears in spectra of hydroxyapatite partially dehydroxylated by thermal treatment was assigned to oxide translation. This band was utilized to search for oxide formation in the laser-irradiated tooth enamel.
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Borggreven JM, van Dijk JW, Driessens FC. Effect of laser irradiation on the permeability of bovine dental enamel. Arch Oral Biol 1980; 25:831-2. [PMID: 6944006 DOI: 10.1016/0003-9969(80)90142-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Goodman BD, Kaufman HW. Effects of an argon laser on the crystalline properties and rate of dissolution in acid of tooth enamel in the presence of sodium fluoride. J Dent Res 1977; 56:1201-7. [PMID: 272381 DOI: 10.1177/00220345770560101501] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Upon exposure to laser radiation, enamel powder mixed with NaF underwent an increase in crystallite size and/or perfection with a significant uptake of fluoride. Incisor teeth lased in the presence of NaF released significantly less calcium and phosphorus into sodium acetate (pH 4.0) compared with unlased controls, suggesting a possible role for the laser in caries prevention.
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Goodman BD, Gwinnett AJ. A comparison of laser- and acid-etched human enamel using scanning electron microscopy. Arch Oral Biol 1977; 22:215-20. [PMID: 326238 DOI: 10.1016/0003-9969(77)90157-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Newesely H. High temperature behaviour of hydroxy- and fluorapatite. Crystalchemical implications of laser effects on dental enamel. J Oral Rehabil 1977; 4:97-104. [PMID: 265369 DOI: 10.1111/j.1365-2842.1977.tb00971.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The application of laser rays for caries prevention as for restorative purposes in oral rehabilitation causes severe changes in the structural and textural assembly of the dental hard tissue. Electron microscopical and X-ray investigations of the new calcium phosphate phases which arise demonstrate a deterioration of the affected tooth regions.
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