Comparative evaluation of two different diode laser wavelengths with and without photosensitization for suppressing bacterial colonization on dental implants surfaces. Ex-vivo study
Valente, Nicola Alberto
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Background: Peri-implant disease is now an important topic in the dental implant literature. Therapeutic use of the the diode laser has shown promising results in management of peri-imlantitis. Photodynamic therapy (PDT) is based on the application of photosensitive dyes activated by light, with a specific wavelengths in order to destroy bacteria. It usually includes three basic elements: low level diode laser, nontoxic photosensitizer, and oxygen. When activated by light, the photosensitizer produces a reactive singlet oxygen, which in turn, causes cell death. The aim of this ex-vivo study is to evaluate the efficacy of diode laser, used at 2 different wavelengths, with or without the aid of indocyanine green photosensitization, in reducing colonization of S.sanguis, on smooth dental implant surfaces. In addition, we assessed the increase of temperature on the implants,after irradiation with the two diode lasers, under conditions that closely replicate those of the human body. Methods: Twenty-two smooth surface sterile implants per group were placed into sterile porcine bone blocks. A standardized angular bony defect was created at the implant coronal bone surface. Defects were inoculated with 10 μL of S. sanguinis. Blocks were then incubated in a 5% CO2, 37 °C atmosphere for 24hours. The implants were then subjected to different treatment protocols: 810nm or 980nm laser, with or without PDT. We used 2 control groups, one non treated by laser, and one non treated but coated with indocyanine green dye, for a total of 6 groups. The laser fiber optic tip was placed into the defects for 60 seconds set at 1.0W continuous. We used an "up-and-down motion" to apply the laser to the angular defect. The treated bone- implant blocks were rinsed with triptic soy broth, and plated in a standard fashion. Colony forming units (CFU) were counted 48 hours after incubation. The irradiation was then repeated without contamination, and initial temperatures were recorded with the aid of thermocouples monitoring the change in temperature until they cooled down to the initial values. The irradiation was repeated, at room temperature, and in a 37°C waterbath with the following settings: 0.6W, 0.8W, 1W continuous and pulsed. Results: Our study shows that both wavelengths minimize CFU counts. The use of PDT showed a modest increase in the decontamination effect, with the difference being more marked in the 810nm group. However, there was no statistically significant difference compared to non-PDT groups. A critical increase in temperature was never observed when the bone block was placed in a 37°C waterbath prior to laser application. Conclusions: The use of diode lasers at 810 and 980nm, in implant surface decontamination is efficacious in this ex-vivo study regardless of the use of indocyanine green PDT and with no dangerous increase of temperature.