FTIR and Raman as a noninvasive probe for predicting the femtosecond laser ablation profile on heterogeneous human teeth

Loganathan, Sarathkumar; Santhanakrishnan, Soundarapandian; Bathe, Ravi; Arunachalam, Muthukumaraswamy

doi:10.1016/j.jmbbm.2020.104256

Cited by 11 publications

(5 citation statements)

References 23 publications

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“…Enamel ablation by femtosecond lasers has been demonstrated by several authors (Chen et al, 2015; Chen et al, 2016; Le, Bertrand, & Vilar, 2016; Loganathan, Santhanakrishnan, Bathe, & Arunachalam, 2021; Yuan, Zheng, Sun, Wang, & Lyu, 2017). Nevertheless, there is no detailed characterization of femtosecond laser‐irradiated surfaces using subablative parameters, since previous studies have demonstrated the ability of high‐power lasers with subablative parameters to make dental enamel more acid‐resistant (Behroozibakhsh et al, 2018; Chang et al, 2017).…”

Section: Discussionmentioning

confidence: 96%

Chemical and morphological changes of femtosecond laser‐irradiated enamel using subablative parameters

Casarin

Mattos

Neto

et al. 2021

Microscopy Res & Technique

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Chemical composition of dental enamel has a great relationship with the prevention of caries. The objective of the present work was to evaluate the chemical and morphological changes of femtosecond laser‐irradiated enamel with subablative parameters using Raman spectroscopy, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). Bovine incisor teeth were used to obtain 30 enamel specimens (5 × 5 mm2). The chemical composition of the control sample was analyzed by Raman spectrometry to acquire the absorption spectrum, delimiting the areas under the carbonate and phosphate bands. This analysis was used to evaluate the change in the chemical composition of the sample after irradiation. The specimens were irradiated (IRR) with a Ti:Sapphire laser system (pulsed and focused modes, femtosecond regime 70 fs, average power of 1 W and exposure time of 15 s). After irradiation, the areas under the carbonate and phosphate absorption bands were delimited in each specimen. Raman spectrometry data were analyzed using Student's t‐test (α = 5%). By comparing the spectra of the IRR and non‐irradiated (NI) specimens, the results showed a significant increase in the area value for the phosphate peaks and a significant reduction in the area value for the carbonate peak and the carbonate:phosphate ratio. CLSM and SEM analyses did not reveal structural alterations in the subsurface nor morphological alterations in the IRR enamel surface, respectively. It was concluded that femtosecond laser irradiation using subablative parameters reduced the carbonate content and the carbonate/phosphate ratio without altering the structure and morphology of the dental enamel.

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Section: Discussionmentioning

confidence: 96%

Chemical and morphological changes of femtosecond laser‐irradiated enamel using subablative parameters

Casarin

Mattos

Neto

et al. 2021

Microscopy Res & Technique

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“…Raman spectroscopy was performed on the walls and oors of the laser-processed grooves [20][21][22][23]. Figure 4 presents the Raman spectra taken on unprocessed enamel (Fig.…”

Section: Investigation Of Structural Modi Cations By Raman Spectroscopymentioning

confidence: 99%

Investigation of laser wavelength effect on the ablation of enamel and dentin using femtosecond laser pulses

Rapp,

Madden,

Brand

et al. 2023

Preprint

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We investigated the effect of femtosecond (fs) laser ablation of enamel and dentin for different pulse wavelengths: infrared (1030 nm), green (515 nm), and ultra-violet (343 nm) and for different pulse separations to determine the optimal irradiation conditions for the precise removal of dental hard tissues with the absence of structural and compositional damage. The ablation rates and efficiencies were established for all three laser wavelengths for both enamel and dentin at room temperature without using any irrigation or cooling system, and the surfaces were assessed with optical and scanning electron microscopy, optical profilometry, and Raman spectroscopy. We demonstrated that 515 nm fs irradiation provides the highest rate and efficiency for ablation, followed by infrared. Finally, we explored the temperature variations inside the dental pulp during the laser procedures for all three wavelengths and showed that the maximum increase at the optimum conditions for both infrared and green irradiations was 5.5˚C, within the acceptable limit of temperature increase during conventional dental treatments. Ultra-violet irradiation significantly increased the internal temperature of the teeth, well above the acceptable limit, and caused severe damage to tooth structures. Thus, ultra-violet is not a compatible laser wavelength for femtosecond teeth ablation.

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“…To clinically harness the extremely high level of precision afforded by the femtosecond laser, we believe it is prudent to have mathematical models that provide precise predictions of the shape of the ablated cavity as a function of laser settings. Recently, Loganathan et al, 24,33,34 proposed an optical penetration model for practical prediction of the ablation of dental material using femtosecond lasers. Their model utilizes an effective waist radius for the laser, an effective attenuation coefficient and the threshold fluence for the material.…”

Section: Introductionmentioning

confidence: 99%

Optical penetration models for practical prediction of femtosecond laser ablation of dental hard tissue

Woodfield,

Rode,

Dao

et al. 2024

Lasers Surg Med

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ObjectivesTo develop and practically test high‐precision femtosecond laser ablation models for dental hard tissue that are useful for detailed planning of automated laser dental restorative treatment.MethodsAnalytical models are proposed, derived, and demonstrated for practical calculation of ablation rates, ablation efficiency and ablated morphology of human dental enamel and dentin using femtosecond lasers. The models assume an effective optical attenuation coefficient for the irradiated material. To achieve ablation, it is necessary for the local energy density of the attenuated pulse in the hard tissue to surpass a predefined threshold that signifies the minimum energy density required for material ionization. A 1029 nm, 40 W carbide 275 fs laser was used to ablate sliced adult human teeth and generate the data necessary for testing the models. The volume of material removed, and the shape of the ablated channel were measured using optical profilometry.ResultsThe models fit with the measured ablation efficiency curve against laser fluence for both enamel and dentin, correctly capturing the fluence for optimum ablation and the volume of ablated material per pulse. The detailed shapes of a 400‐micrometer wide channel and a single‐pulse width channel are accurately predicted using the superposition of the analytical result for a single pulse.ConclusionsThe findings have value for planning automated dental restorative treatment using femtosecond lasers. The measurements and analysis give estimates of the optical properties of enamel and dentin irradiated with an infrared femtosecond laser at above‐threshold fluence and the proposed models give insight into the physics of femtosecond laser processing of dental hard tissue.

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FTIR and Raman as a noninvasive probe for predicting the femtosecond laser ablation profile on heterogeneous human teeth

Cited by 11 publications

References 23 publications

Chemical and morphological changes of femtosecond laser‐irradiated enamel using subablative parameters

Chemical and morphological changes of femtosecond laser‐irradiated enamel using subablative parameters

Investigation of laser wavelength effect on the ablation of enamel and dentin using femtosecond laser pulses

Optical penetration models for practical prediction of femtosecond laser ablation of dental hard tissue

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