Penetration Depth of Initiated and Non-Initiated Diode Lasers in Bovine Gingiva

Background: This study aimed to evaluate the penetration depth of 445 and 970 nm diode lasers using both initiated and non-initiated fibers on bovine gingiva in an ex vivo model. Methods: In this in vitro experiment, 445 nm and 970 nm diode lasers were compared in pulsed (35 Hz, duty cycle: 50%) and continuous mode with both initiated and non-initiated tips. All experimental groups had laser output settings of 2 Watts with a 320 mu m thick glass fiber utilized for delivery. Two posterior teeth were randomly selected from four bovine mandibles for each group. The teeth were irradiated for 30 s buccal and 30 s lingual before the gingiva was harvested for histological evaluation. Samples were fixed in 10% formalin and stained via elastin Van Gieson. Sections were examined microscopically to evaluate collagen denaturation due to thermal effects, which were measured and compared using a mixed-effect model with Tukey adjustment. Results: The 445 nm wavelength groups displayed significantly higher penetration depths when compared to the 970 nm wavelength groups. The initiated tip groups tended to display a lower penetration depth than non-initiated groups; however, these values were similar (p > 0.05) for the 445 nm pulsed lasers (initiated vs. non-initiated). Conclusions: We can conclude that the 445 nm laser wavelength displayed greater thermal denaturation in bovine gingiva ex vivo when compared to the 970 nm wavelength. Additionally, the pulsed settings displayed less thermal penetration depth when compared to the continuous emission modes of the same power output. However, additional studies are necessary to better compare initiated and non-initiated tips using the novel blue laser light.