An easily achievable strategy to promote the penetration of methylene blue into dentinal tubules

Wang, Yanhuang; Li, Yijun; Huang, Shan; Huang, Jinguo; Huang, Xiaojing

doi:10.1016/j.pdpdt.2022.103237

Cited by 7 publications

(9 citation statements)

References 42 publications

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“…Surrounding tissue optical properties were set to those measured prior to the administration of MB. This was meant to simulate the relatively shallow penetration of MB into tissue observed in prior studies (Genina et al 2002 , Bashkatov et al 2005 , Kosarieh et al 2021 , Wang et al 2023 ). To examine the effects of this assumption, we also simulated an artificial condition where optical properties measured post-MB were assigned to the abscess wall and surrounding tissue.…”

Section: Resultsmentioning

confidence: 99%

“…The abscess wall, consisting of a 200 μ m thick layer immediately surrounding the abscess, was assigned optical properties corresponding to post-MB spectroscopy. The thickness of this layer was based upon reports showing similar diffusion of MB into various tissue types after application at the surface (Genina et al 2002 , Bashkatov et al 2005 , Kosarieh et al 2021 , Wang et al 2023 ). The surrounding tissue was set to pre-MB optical properties.…”

Section: Methodsmentioning

confidence: 99%

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Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2024

Phys. Med. Biol.

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Photodynamic therapy (PDT) is an effective antimicrobial therapy that we used to treat human abscess cavities in a Phase 1 clinical trial. This trial included pre-PDT measurements of abscess optical properties, which affect light dose (light fluence) at the abscess wall and PDT response. This study simulated PDT treatment planning for 13 subjects that received optical spectroscopy prior to clinical PDT, to determine the impact of measured optical properties on ability to achieve fluence rate targets in 95% of the abscess wall. Retrospective treatment plans were evaluated for 3 conditions: (1) clinically delivered laser power and assumed, homogeneous optical properties, (2) clinically delivered laser power and measured, homogeneous optical properties, and (3) with patient-specific treatment planning using measured, homogeneous optical properties. Treatment plans modified delivered laser power, intra-cavity Intralipid (scatterer) concentration, and laser fiber type. Using flat-cleaved laser fibers, the proportion of subjects achieving 95% abscess wall coverage decreased significantly relative to assumed optical properties when using measured values for 4 mW/cm2 (92% vs. 38%, p=0.01) and 20 mW/cm2 (62% vs. 15%, p=0.04) thresholds. When measured optical properties were incorporated into treatment planning, the 4 mW/cm2 target was achieved for all cases. After treatment planning, optimal Intralipid concentration across subjects was 0.14 ± 0.09%, whereas 1% was used clinically. Required laser power to achieve the 4 mW/cm2 target was significantly correlated with measured abscess wall absorption (ρ=0.7, p=0.008), but not abscess surface area (ρ=0.2, p=0.53). When using spherical diffuser fibers for illumination, both optimal Intralipid concentration (p=0.0005) and required laser power (p=0.0002) decreased compared to flat cleaved fibers. At 0% Intralipid concentration, the 4 mW/cm2 target could only be achieved for 69% of subjects for flat-cleaved fibers, compared to 100% for spherical diffusers. Based on large inter-subject variations in optical properties, individualized treatment planning is essential for abscess photodynamic therapy.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2024

Phys. Med. Biol.

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“…As we have shown here, simulation of a thin layer representing MB penetration results in a much larger proportion of subjects being eligible for PDT. However, the penetration depth assumed here is based upon reports in other tissue types for MB [26][27][28][29] , rather than those determined directly in abscesses. This motivates direct measurement of MB depth penetration into abscess tissue.…”

Section: Discussionmentioning

confidence: 99%

“…The abscess wall, consisting of a 200 µm thick layer immediately surrounding the abscess, was assigned optical properties corresponding to post-MB spectroscopy. The thickness of this layer was based upon reports showing similar diffusion of MB into various tissue types after application at the surface [26][27][28][29] . The surrounding tissue was set to pre-MB optical properties.…”

Section: Treatment Planning Softwarementioning

confidence: 99%

“…Surrounding tissue optical properties were set to those measured prior to the administration of MB. This was meant to simulate the relatively shallow penetration of MB into tissue observed in prior studies [26][27][28][29] . To examine the effects of this assumption, we also simulated an artificial condition where optical properties measured post-MB were assigned to the abscess wall and surrounding tissue.…”

Section: Assumption Of Post-mb Optical Propertiesmentioning

confidence: 99%

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Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2023

Preprint

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Background: Photodynamic therapy (PDT) is an effective antimicrobial therapy that we used to treat human abscess cavities in a recently completed Phase 1 clinical trial. This trial included pre-PDT measurements of abscess optical properties, which affect the expected light dose to the abscess wall and eventual PDT response. Purpose: The objective of this study was to simulate PDT treatment planning for the 13 subjects that received optical spectroscopy prior to clinical abscess PDT. Our goal was to determine the impact of these measured optical properties on our ability to achieve fluence rate targets in 95% of the abscess wall. Methods: During a Phase 1 clinical trial, 13 subjects received diffuse reflectance spectroscopy prior to PDT in order to determine the optical properties of their abscess wall. Retrospective treatment plans seeking to achieve fluence rate targets in 95% of the abscess wall were generated for all subjects for 3 conditions: (1) at the laser power delivered clinically with assumed optical properties, (2) at the laser power delivered clinically with measured optical properties, and (3) with patient-specific treatment planning using these measured optical properties. Factors modified in treatment planning included delivered laser power and intra-cavity Intralipid (scatterer) concentration. The effects of laser fiber type were also simulated. Results: Using a flat-cleaved laser fiber, the proportion of subjects that achieved 95% abscess wall coverage decreased significantly when incorporating measured optical properties for both the 4 mW/cm^2 (92% vs. 38%, p=0.01) and 20 mW/cm^2 (62% vs. 15%, p=0.04) fluence rate thresholds. However, when measured optical properties were incorporated into treatment planning, a fluence rate of 4 mW/cm^2 was achieved in 95% of the abscess wall for all cases. In treatment planning, the optimal Intralipid concentration across subjects was found to be 0.14 +/- 0.09% and the optimal laser power varied from that delivered clinically but with no clear trend (p=0.4). The required laser power to achieve 4 mW/cm^2 in 95% of the abscess wall was significantly correlated with measured absorption at the abscess wall (rho=0.7, p=0.008), but not abscess surface area (rho=0.2, p=0.53). When using spherical diffuser fibers as the illumination source, the optimal intralipid concentration decreased to 0.028 +/- 0.026% (p=0.0003), and the required laser power decreased also (p=0.021), compared to flat cleaved fibers. If the intra-cavity lipid emulsion (Intralipid) was replaced with a non-scattering fluid, all subjects could achieve the 4 mW/cm^2 fluence rate threshold in 95% of the abscess wall using a spherical diffuser, while only 69% of subjects could reach the same criterion using a flat cleaved fiber. Conclusions: The range of optical properties measured in human abscesses reduced coverage of the abscess wall at desirable fluence rates. Patient-specific treatment planning including these measured optical properties could bring the coverage back to desirable levels by altering the Intralipid concentration and delivered optical power. These results motivate a future Phase 2 clinical trial to directly compare the efficacy of patient-specific-treatment planning with fixed doses of Intralipid and light.

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In vitro effects of Er: YAG laser-activated photodynamic therapy on Enterococcus faecalis in root canal treatment

Yang,

Chen

2024

Photodiagnosis and Photodynamic Therapy

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An easily achievable strategy to promote the penetration of methylene blue into dentinal tubules

Cited by 7 publications

References 42 publications

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

In vitro effects of Er: YAG laser-activated photodynamic therapy on Enterococcus faecalis in root canal treatment

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