Background and Objective: Extraoral photobiomodulation therapy (PBM Therapy) is a novel treatment for the prevention of oral mucositis, a painful side effect of myeloablative chemotherapy, and there are no standardized dosimetry protocols for this procedure. We used Monte Carlo modeling to determine optimal parameters for a safe and efficacious treatment. The objective of this work was to experimentally validate the results of Monte Carlo dose modeling of extraoral PBM Therapy by conducting a pilot validation study.
Methods: Light penetration through the right cheek of four volunteers with skin types I-VI was measured. A 69-LED array with an area of 31.2 cm2 was applied to the external cheek delivering 26 mW/cm2 at 850 nm to the surface. Power density at the intraoral mucosa was recorded under a controlled pressure of 18gm/cm2.
To obtain morphological information, we acquired T1 weighted MRI images of the volunteers' heads and measured the thickness of the skin, fat, and muscle layers of the cheek of each volunteer. These anatomical data together with the optical properties from the literature were used to simulate light propagation through the right cheek.
Results and Conclusions: Our study revealed that experimental and simulation results were in good agreement for all 4 subjects. The difference between the mean values of the measured fluence rates was within 16% from the respective fluence rates obtained using Monte Carlo simulations. We confirmed that there was no temperature increase due to illumination. Monte Carlo modeling is a robust and reliable method for PBM Therapy light dosimetry.
Photobiomodulation (PBM) therapy, previously known as low-level laser therapy, was discovered more than 50 years ago, yet there is still no agreement on the parameters and protocols for its clinical application. Some groups have recommended the use of a power density less than 100 mW/cm2 and an energy density of 4 to 10 J/cm2 at the level of the target tissue. Others recommend as much as 50 J/cm2 at the tissue surface. The wide range of parameters that can be applied (wavelength, energy, fluence, power, irradiance, pulse mode, treatment duration, and repetition) in some cases has led to contradictory results. In our review, we attempt to evaluate the range of effective and ineffective parameters in PBM. Studies in vitro with cultured cells or in vivo with different tissues were divided into those with higher numbers of mitochondria (muscle, brain, heart, nerve) or lower numbers of mitochondria (skin, tendon, cartilage). Graphs were plotted of energy density against power density. Although the results showed a high degree of variability, cells/tissues with high numbers of mitochondria tended to respond to lower doses of light than those with lower number of mitochondria. Ineffective studies in cells with high mitochondrial activity appeared to be more often due to over-dosing than to under-dosing.
Oral mucositis is a debilitating and dose limiting side effect of oncotherapy in cancer patients. Low Level Laser Therapy (LLLT) is a promising new intervention for the treatment of oral mucositis. Aims and objectives: 1. Perform a systematic review of available literature on the therapeutic effect of LLLT on established oral mucositis. 2. Formulate recommendations for future studies based on results of review. Methods: Electronic search oflow level laser therapy in the treatment of oral mucositis was conducted and eligible studies reviewed. Results: Four studies met the inclusion criteria and were analyzed. A total of 109 patients were included, 59 of which received LLLT as a therapeutic measure. An overall success rate of 81.4% success rate was reported in regard to OM. Conclusion: The review demonstrated the positive therapeutic effect of LLLT on oral mucositis. However, the need for future studies with standardized reporting of parameters and methods is needed to increase the level of evidence of this intervention.
Samples of bone, dentin and enamel were stored in distilled water, 10% neutral buffered formalin, 70% ethyl alcohol or
6% sodium hypochlorite solutions for fifteen days. Other samples were stored in the same solutions for 36 hours and
then transferred to distilled water for the remainder of the fifteen day period. Finally, samples than had been stored dry
for up to 5 years were rehydrated and ablated. All enamel specimens appeared unaffected by the storage conditions.
Dentin samples were very significantly affected by all storage methods. Bone samples were affected by most storage
conditions. Samples stored in sodium hypochlorite had as much as a 100 percent increase in ablation rate. Surprisingly,
dry stored samples that were reconstituted for 36 hours ablated at virtually the same rate as those stored in distilled
water. None of the storage conditions studied produced ablation rates that mirrored in vivo ablation. Sterilization by
autoclave is the only reliable and safe method studied but cannot be used on teeth with amalgam fillings for safety
reasons. Teeth with fillings should be stored in 10% neutral bufferred formalin for a minimum of one week.