&lt;title&gt;Optoacoustic effects during Er:YAG laser ablation in hard dental tissue&lt;/title&gt;

Lukač, Matjaž; Grad, Ladislav; Možina, Janez; Sustercic, Dusan; Funduk, Nenad; Skalerić, U

doi:10.1117/12.197595

Cited by 5 publications

(8 citation statements)

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“…However, with standard, bell or quasisquare-shaped erbium pulse modes, 13 these requirements are to a certain extent contradictory, as parameters that may be optimal, e.g., achieving fastest ablation, may not be optimal when minimal vibrations and noise are required. 14,15 For example, it is well understood that ablation thresholds decrease toward shorter pulse durations, [16][17][18][19] where short pulses are pulses shorter than the thermal relaxation time of the ablated tissue. 18,19 At shorter times, the energy has little time to escape from the ablated volume, and so less heat is diffused into the surrounding tissue.…”

Section: Introductionmentioning

confidence: 99%

“…5,27 However, this approach may not be always appropriate since, especially for tissues with relatively low water content, the ablation efficacy has been observed to get progressively reduced upon consecutive delivery of laser pulses. 28,29 When using such cumulative ablation methods, the measurement process influences the ablation process, which is being studied, and therefore, erroneous results and conclusions may be reached. For example, it is well known that for dental enamel, the ablation process completely stalls after a consecutive delivery of ∼10 laser pulses, unless the enamel is cooled by an external water spray.…”

Section: Introductionmentioning

confidence: 99%

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Ablation characteristics of quantum square pulse mode dental erbium laser

et al. 2016

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Erbium lasers are by now an accepted tool for performing ablative medical procedures, especially when minimal invasiveness is desired. Ideally, a minimally invasive laser cutting procedure should be fast and precise, and with minimal pain and thermal side effects. All these characteristics are significantly influenced by laser pulse duration, albeit not in the same manner. For example, high cutting efficacy and low heat deposition are characteristics of short pulses, while vibrations and ejected debris screening are less pronounced at longer pulse durations. We report on a study of ablation characteristics on dental enamel and cementum, of a choppedpulse Er:YAG [quantum square pulse (QSP)] mode, which was designed to reduce debris screening during an ablation process. It is shown that in comparison to other studied standard Er:YAG and Er,Cr:YSGG laser pulse duration modes, the QSP mode exhibits the highest ablation drilling efficacy with lowest heat deposition and reduced vibrations, demonstrating that debris screening has a considerable influence on the ablation process. By measuring single-pulse ablation depths, we also show that tissue desiccation during the consecutive delivery of laser pulses leads to a significant reduction of the intrinsic ablation efficacy that cannot be fully restored under clinical settings by rehydrating the tooth using an external water spray.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ablation characteristics of quantum square pulse mode dental erbium laser

et al. 2016

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“…It also improves ablation efficiency (AE) in enamel by preventing a reduction or even stalling without further tissue removal when a series of laser pulses is delivered to the tissue. [8][9][10][11][12][13][14][15][16][17][18] As shown by measurements of the optoacoustic signal for a series of consecutive Er:YAG laser pulses, the optoacoustic energy is larger for initial pulses and is reduced toward the end of the pulse sequence. 11,12 With water applied in-between pulses, no reduction in the optoacoustic signal is observed.…”

Section: Introductionmentioning

confidence: 99%

Measurements of erbium laser-ablation efficiency in hard dental tissues under different water cooling conditions

Kuščer

Diaci

2013

J. Biomed. Opt

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Laser triangulation measurements of Er:YAG and Er,Cr:YSGG laser-ablated volumes in hard dental tissues are made, in order to verify the possible existence of a "hydrokinetic" effect that has been proposed as an alternative to the "subsurface water expansion" mechanism for hard-tissue laser ablation. No evidence of the hydrokinetic effect could be observed under a broad range of tested laser parameters and water cooling conditions. On the contrary, the application of water spray during laser exposure of hard dental material is observed to diminish the laser-ablation efficiency (AE) in comparison with laser exposure under the absence of water spray. Our findings are in agreement with the generally accepted principle of action for erbium laser ablation, which is based on fast subsurface expansion of laser-heated water trapped within the interstitial structure of hard dental tissues. Our measurements also show that the well-known phenomenon of ablation stalling, during a series of consecutive laser pulses, can primarily be attributed to the blocking of laser light by the loosely bound and recondensed desiccated minerals that collect on the tooth surface during and following laser ablation. In addition to the prevention of tooth bulk temperature buildup, a positive function of the water spray that is typically used with erbium dental lasers is to rehydrate these minerals, and thus sustaining the subsurface expansion ablation process. A negative side effect of using a continuous water spray is that the AE gets reduced due to the laser light being partially absorbed in the water-spray particles above the tooth and in the collected water pool on the tooth surface. Finally, no evidence of the influence of the water absorption shift on the hypothesized increase in the AE of the Er,Cr:YSGG wavelength is observed.

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“…These so-called optodynamic phenomena have received considerable attention in the context of characterization of laser ablation. Various set-ups have been examined for this purpose: spatially resolved techniques, such as schlieren [9] and [10], shadowgraphy [11] to [14] or holography [15], as well as the temporally resolved ones: laser interferometer [16] to [18], laser beam deflection probe [19] and [20] and capacitive or piezoelectric acoustic sensors [7], [8] and [21]. While most of these techniques represent useful research tools within controlled laboratory experiments, only a few of them exhibit the potential to be used for on-line process monitoring in real medical applications.…”

Section: Introductionmentioning

confidence: 99%

“…Existing methods of shock wave characterization using acoustic sensors rely on empirically selected signal features, such as acoustic signal energy, signal amplitude and time of flight [7], [21] and [22]. Relationships of these signal features to other influencing factors (e.g.…”

Section: Introductionmentioning

confidence: 99%