Peripheral thermal and mechanical damage to dentin with microsecond and sub‐microsecond 9.6 μm, 2.79 μm, and 0.355 μm laser pulses

Rosa, Alfredo Dela; Sarma, Anupama V.; Le, Charles Q.; Jones, Robert S.; Fried, Daniel

doi:10.1002/lsm.20090

Cited by 58 publications

(46 citation statements)

References 31 publications

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“…In the mid-infrared range, specifically at wavelengths that are strongly absorbed by dental hard tissue, microsecond pulses likely require less water cooling to prevent peripheral thermal damage. 31 The pulse width applied in the present study (5 ns) is significantly shorter than the thermal diffusion time of carious dentin, so it is expected to incur minimal thermal damage and allow less water spray.…”

Section: Discussionmentioning

confidence: 96%

“…[4][5][6][7] Excellent high-speed precise ablation of dental caries has been achieved by pulsed CO 2 lasers with the wavelengths of 9.6 and 9.3 μm. [25][26][27][28][29][30][31] Dental target selectivity using CO 2 lasers, Nd:YAG laser, and lasers with the wavelengths of 355, 377, and 400 nm has also been reported. [32][33][34][35][36] The present study of selective laser-based ablation for carious dentin is entirely novel.…”

Section: Discussionmentioning

confidence: 99%

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Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

et al. 2015

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Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 µm Abstract. Less invasive methods for treating dental caries are strongly desired. However, conventional dental lasers do not always selectively remove caries or ensure good bonding to the composite resin. According to our previous study, demineralized dentin might be removed by a nanosecond pulsed laser operating at wavelengths of around 5.8 μm. The present study investigated the irradiation effect of the light on carious human dentin classified into "remove," "not remove," and "unclear" categories. Under 5.85-μm laser pulses, at average power densities of 30 W∕cm 2 and irradiation time of 2 s, the ablation depth of "remove" and "not remove," and also the ablation depth of "unclear" and "not remove," were significantly different (p < 0.01). The ablation depth was correlated with both Vickers hardness and Ca content. Thus, a nanosecond pulsed laser operating at 5.85 μm proved an effective less-invasive caries treatment.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

et al. 2015

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“…Specific laser conditions were chosen for this study that have been found to produce minimal thermal modification of the dentin 22 . Laser irradiation can induce changes in the birefringence and roughness of the dentin surface that may interfere with the ability of PS-OCT to assess the lesion severity.…”

Section: Introductionmentioning

confidence: 99%

Imaging natural and artificial demineralization on dentin surfaces with polarization sensitive optical coherence tomography

2008

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The purpose of this study was to assess the potential of polarization sensitive optical coherence tomography (PS-OCT) to measure non-destructively the severity of natural and artificial caries lesions in dentin and determine the efficacy of intervention with anti-caries agents. Although several studies have demonstrated the utility of PS-OCT to image caries lesions in enamel and to quantify the lesion severity, only a few studies have focused on lesions in dentin. In this study images of natural root caries lesions on extracted human teeth were acquired with PS-OCT. In addition artificial lesions were produced in dentin after 12 days of exposure to a demineralization solution at a pH of 5.0. Before exposure, three incisions were made on the sample surfaces using Er:YAG laser irradiation and selected areas were treated with topical fluoride. PS-OCT images were acquired using a high power (45-mw) 1310-nm superluminescent diode with a bandwidth of 35-nm. PS-OCT was able to measure demineralization in dentin to a depth of ~ 1 mm. Polarized light microscopy and microradiography were used to measure lesion severity on histological thin sections for comparison. PS-OCT successfully measured the inhibition of demineralization by topical fluoride. Er:YAG laser irradiation did not significantly increase or decrease the rate of dentin demineralization. Keywords polarization; optical coherence tomography; Er:YAG laser; dentin; laser ablation; caries inhibition; thermal damage; topical fluoride INTRODUCTIONSeveral studies over the past few years have demonstrated that optical coherence tomography (OCT) can be used to measure natural and artificial caries lesions on enamel surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13] . Although the penetration depth of near-IR light is considerably less in dentin than for enamel due to the higher scattering coefficient of dentin, PS-OCT and OCT images of dentin with root caries show that penetration depths of ~ 1 mm can be achieved and demineralized dentin can be discriminated from sound dentin and cementum 8,14 . * daniel.fried@ucsf.edu, 415-502-6641. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptOptical coherence tomography (OCT) is a noninvasive technique for creating cross-sectional images of internal biological structure 15,16 . Depth-resolved measurements of caries lesions can be acquired on enamel surfaces [17][18][19][20][21] . In contrast to sound enamel that is highly transparent in the near-IR, sound dentin strongly scatters light in the near-IR and is highly birefringent. Therefore, there is some question whether the same approach employed to assess the severity of demineralization on enamel surfaces can be applied to the surface of dentin. We have shown that for enamel surfaces demineralized areas on the tooth depolarize incident linearly polarized light and the reflectivity in the (⊥) polarization state can be directly integrated to provide a measure of the lesion severity.PS-OCT is well-suited for imaging thermal changes...

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“…Picosecond lasers have been tested, but enamel or dentine cracking has been observed (Lizarelli et al 1999, Swift et al 2001, Niemz 1998. Lasers with nanosecond pulses may or may not induce significant thermal or mechanical damage, depending on the wavelength (Patel et al 1994, Lee et al 2000, Papagiakoumou et al 2004, Dela Rosa et al 2004. The most promising laser with nanosecond pulse duration has a wavelength of 193 nm which causes very little thermal and mechanical damage to teeth because the main mechanism of ablation has a photochemical nature.…”

Section: Introductionmentioning

confidence: 99%

The role of mesoscopic modelling in understanding the response of dental enamel to mid-infrared radiation

Verde¹,

Ramos²,

Stoneham³

2007

Phys. Med. Biol.

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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 µm and Er:YAG at 2.94 µm). 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 ≈10 µs 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 µs duration can induce high stress transients which may cause unwanted cracking.

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Peripheral thermal and mechanical damage to dentin with microsecond and sub‐microsecond 9.6 μm, 2.79 μm, and 0.355 μm laser pulses

Cited by 58 publications

References 31 publications

Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

Imaging natural and artificial demineralization on dentin surfaces with polarization sensitive optical coherence tomography

The role of mesoscopic modelling in understanding the response of dental enamel to mid-infrared radiation

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