Gingival Depigmentation Using 445, 940, and 2780 nm Lasers at Various Settings Evaluated By Optical Coherence Tomography and Confocal Laser Microscopy

Abstract

Several different techniques including lasers have been used for gingival depigmentation to date. The diversity of the wavelengths, application methods, and settings used in laser treatments has necessitated the development of application standards that meet the biological requirements of the tissues while ensuring the esthetic effects of the used methods. Thus, the aim of our study was to evaluate the tissue effects of lasers with wavelengths of 445, 940, and 2780 nm and various laser settings by using optical coherence tomography (OCT) and confocal laser microscopy. Fifty-four dark pigmented gingival biopsy specimens were randomly divided into 9 groups and treated using a 445 nm diode laser (200-400 mW, 320 µm tip, continuous wave [cw], non-contact mode), 940 nm diode laser (600-800 mW, 400 µm tip, cw, contact mode) or 2780 nm laser (1.5-2.5 W, MC3 chisel tip, 30 Hz, 30% air, 40% water, contact mode). Every setting was repeated in 5 depigmentation procedures. The treated gingival samples were examined using the CIRRUS OCT 5000 device (Carl Zeiss Meditec Inc., Germany) and the laser confocal microscope Olympus LEXT OLS5000 (Olympus Corporation, Tokyo, Japan) immediately after laser irradiation. All examined wavelengths could effectively remove gingival melanin pigmentations. The Er,Cr:YSGG laser (2780 nm) was especially effective and safe for gingival depigmentation because of its very thin effective laser trace and power range between 1.5 and 2.0 W together with the continual scanning movement of the laser tip, which yielded optimal depigmentation for gingival tissue. With the 940 nm diode laser, the effective power range that did not involve damage to the lower structures ranged between 600 and 700 mW, cw, with continual movement of the laser tip. Moreover, non-contact application of the 445 nm laser using only 200 mW power in the continuous mode appeared to be a promising method for gingival depigmentation.