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ePaper created 2018-04-25, 08:59:39 | version 1.38.0
28 ◊Page 26 RESTORATIVE Dental Tribune Middle East & Africa Edition | 2/2018 Case outline A 26-year-old female patient of Chinese ancestry presented with melanin pigmentation in 2007. Con- genital melanin pigmentation of the labial gingiva was diagnosed. Depig- mentation on the upper arch us- ing 810 nm at 30 W, 20 kHz, 16 µsec was carried out. Eight years post-op showed mild relapse of pigmenta- tion, but the patient was satisfied with the cosmetic appearance (Figs. 3–6). She now wanted the melanin pigment on her lower anterior seg- ment to be removed (Fig. 8). Purpose Pigment removal in the requested sites was discussed using 445 nm di- ode laser. The same technique would be used and the patient consented to the treatment. Fig. 14: Diagram 3. Fig. 15: Diagram 4. during the treatment. There is no surface ablation of the pigmented mucosa but rather the haemoglo- bin and melanin absorbing the laser energy (Fig. 2). This technique (Figs. 3–6) showed a treatment time of two minutes compared to the ablative technique time up to 30 minutes in an area of first premolar to first pre- molar of one dental arch. The wavelength of 445 nm is much better absorbed by melanin and haemoglobin than 810 nm (Fig. 7). Hence, a much lower power density may be used to produce the same effect. The fast way to esthetic perfection. The natural fine-structure feldspar veneering ceramic for zirconia frameworks. E 9 1 5 3 VITAVM®9 • Excellent light dynamics and optimum physical properties thanks to the fi ne-structure ceramic • Excellent modeling characteristics for fast and accurate application of the ceramic • Process reliability thanks to long-standing experience www.vita-zahnfabrik.com facebook.com/vita.zahnfabrik VITA – perfect match. Material and method SIROLaser Blue (Dentsply Sirona) with an emission wavelength of 445 nm was used at 1 W, cw delivered through a 320 µ m fiber. Procedure Depigmentation technique is the same as described with the 810 nm wavelength (above). Under local an- aesthesia, a non-initiated 320 µm fiber delivers the energy at a distance of 2 mm to the pigmented area with constant movement. Immediate change to pink colour without sur- face ablation of the pigmented mu- cosa was observed. The procedure took approximately 40 seconds to complete between lower left and right canine region. Results In this case, the mucosa turns pink without any signs of surface mu- cosal ablation except one spot be- tween teeth 31, 32 (Fig. 9). Sub-surface coagulation of blood vessels gave a pink coloured appearance. There was very mild post-op discomfort for about one hour after loss of the an- aesthetic effect. No analgesics were required as the discomfort feeling disappeared fast. Laser peeling of mucosa between 31 and 41 was noted during photo- graph taking at one day post-op re- view (Figs. 10 and 11). The three day post-op photo taken by the patient showed that the laser peel disap- peared with new gingival mucosa formation (Fig. 12). Two weeks post- op showed complete recovery of the gingival mucosa without melanin pigmentation (Fig. 13). Discussion There has not been much informa- tion on this new wavelength. From Fig. 7, the absorption coefficient for haemoglobin is estimated at 7 x 10²/ cm–1 and 10³/cm-1 for melanin. Pen- etration depth for haemoglobin is calculated at 140 µm and 10 µm for melanin. The penetration depth of haemoglobin and melanin with 810 nm are 2 mm and 0.1 mm respec- tively. Furthermore, scattering curve showed higher tissue scattering ef- fect with 445 nm than 810 nm. In comparison with the NIR diode lasers, the absorption of collagen and scattering increases in the blue light spectrum. In view of the above to- gether with high absorption of hae- moglobin and melanin to 445 nm, 1 W cw was used. Power density of 88 W/cm² (Fig. 14) delivering at 88 J/cm² fluence at 2 mm distance was calcu- lated. Although the power density of 1,697 W/cm² (Fig. 15) delivering 543 J/ cm² fluence used by 810 nm is high- er than 445 nm delivered, the eight years post-op showed stable gingi- val contour with no recession (Fig. 6). The understanding of the optical properties of the wavelength, power parameters and laser tissue interac- tion are important information for the clinician to achieve the desired treatment outcome. Conclusion The use of 1 W cw 445 nm blue diode laser is effective in non-ablative de- pigmentation of oral mucosa. This non-ablative technique provide im- mediate aesthetic result with very short procedure time. To the au- thor’s knowledge, this is the first case presented using 445 nm for melanin depigmentation. Editorial note: A list of references is available from the publisher. Dr Luk reports no potential conflicts of interest.