Influence of blue and violet LED and infrared laser on the temperature of bleaching protocols in different concentrations of hydrogen peroxide.

BACKGROUND: The photo-acceleration of bleaching gels by lights has been extensively researched. However, the induced temperature increase during this process needs to be further evaluated to prevent damage to the dental pulp. Therefore, the objective of this study was to evaluate the surface and intrapulpal temperature kinetics of different concentrations of hydrogen peroxide (HP) gels photo-accelerated by blue or violet light and infrared laser. METHODS: The whitening gels at concentrations of HP35, HP15, and HP6 % were irradiated with blue and violet LED/laser on the surface of a human canine tooth. The surface temperature variation (∆Ts) was evaluated using a pH meter, while the intrapulpal temperature variation (∆Ti) was assessed using a digital thermometer at intervals of 1, 15, and 30 min. Statistical analysis was conducted using a Two-way repeated measures ANOVA test, and Bonferroni post-test was applied at a significance level of 5 %. RESULTS: All violet LED photo-accelerated groups showed a higher increase in ∆Ts compared to the blue LED/laser groups. However, there were no significant differences between the groups for ∆Ti. CONCLUSION: Although the photo-acceleration of HP35 and HP15 % gels with violet LED/laser has a greater increase in surface temperature compared to HP6 % gel, the different light systems do not significantly increase the intrapulpal temperature.

How can biophotonics help dentistry to avoid or minimize cross infection by SARS-CoV-2?

Biophotonics is defined as the combination of biology and photonics (the physical science of the light). It is a general term for all techniques that deal with the interaction between biological tissues/cells and photons (light). Biophotonics offers a great variety of techniques that can facilitate the early detection of diseases and promote innovative theragnostic approaches. As the COVID-19 infection can be transmitted due to the face-to-face communication, droplets and aerosol inhalation and the exposure to saliva, blood, and other body fluids, as well as the handling of sharp instruments, dental practices are at increased risk of infection. In this paper, a literature review was performed to explore the application of Biophotonics approaches in Dentistry focusing on the COVID-19 pandemic and how they can contribute to avoid or minimize the risks of infection in a dental setting. For this, search-related papers were retrieved from PubMED, Scielo, Google Schoolar, and American Dental Association and Centers for Disease Control and Prevention databases. The body of evidence currently available showed that Biophotonics approaches can reduce microorganism load, decontaminate surfaces, air, tissues, and minimize the generation of aerosol and virus spreading by minimally invasive, time-saving, and alternative techniques in general. However, each clinical situation must be individually evaluated regarding the benefits and drawbacks of these approaches, but always pursuing less-invasive and less aerosol-generating procedures, especially during the COVID-19 pandemic.

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

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.