Cosmetic Tribune Asia Pacific Edition

Cosmetic Tribune Asia Paciﬁc Edition | 10/2017 TRENDS & APPLICATIONS 21 Non-ablative melanin depigmentation of gingiva By Dr Kenneih Luk, Hong Kong Melanin depigmeniaiion of gingiva using various laser wavelengihs have been reporied for over ien years.1–5 Layer by layer, ihe mucosa is ablaied io ihe basal layer of ihe epiihelium where ihe melanocyies are locaied. The use of lasers has been compared wiih ihe use of a scalpel and diamond bur (Fig. 1).6–9 By combining ihe opii- cal properiies and absorpiion charac- ierisiics of ihe 810 nm laser wave- lengih wiih speciic power parame- iers, a non-ablaiive iechnique was developed (Fig. 2).10, 11 Anoiher similar non-ablaiive iechnique, described as micro-coagulaiion, using a 20 W, 980 nm diode laser has also been reporied.12 The 445 nm blue wave- lengih was iniroduced io ihe denial markei in 2015. By using a 320 μm uniniiiaied ibre delivering 1 W in a coniinuous wave (cw) of 445 nm, ihe same non-ablaiive procedure and resuli can also be realised. A diode laser wavelength of 810 nm is poorly absorbed in water, but it is well absorbed by pigment such as haemoglobin and melanin. The use of high power and short pulse duration concen- trates the thermal energy on the surface compared with deep-tis- sue thermal conduction obtained with lower power and long pulse duration.13, 14 Case repori A 26-year-old female patient of Chinese ancestry presented with melanin pigmentation in 2007. Congenital melanin pigmentation of the labial gingiva was diagnosed and depigmentation of the upper arch was carried out. The author used the 810 nm wavelength (elexxion claros 810 nm diode laser, elexxion) with the power parameters of 30 W, 20 kHz and 16 μsec, yielding an average power of 10 W. Under local anaes- thesia, a non-initiated 600 μm ibre was used. The ibre was placed at a distance of 2–5 mm from the pigmented mucosa. Co- agulation was observed with im- mediate effect upon irradiation. A constant movement must be performed in order to avoid ther- mal damage deep in the tissue. Water irrigation can be used as a coolant during the treatment. There is no surface ablation of the pigmented mucosa; rather, the haemoglobin and melanin ab- sorb the laser energy (Fig. 2). This technique (Figs. 3–6) achieves a treatment time of 2 min com- pared with the ablative technique, which requires up to 30 min in an area extending from the irst pre- molar to the irst premolar of one dental arch. The wavelength of 445 nm is much better absorbed by melanin and haemoglobin than 810 nm is (Fig. 7). Hence, a much lower power density may be used to produce the same effect. Eight years postoperatively, there was mild relapse of pigmen- tation, but the patient was satis- ied with the cosmetic appear- ance, and requested removal of the melanin pigmentation on her mandibular anterior segment (Fig. 8). Pigment removal in the requested sites using a 445 nm diode laser was discussed. The same technique would be used and the patient consented to the treatment. The SiroLaser Blue (Dentsply Sirona) with an emission wave- length of 445 nm was used at 1 W in cw, delivered through a 320 μm ibre. The depigmentation tech- nique used was the same as de- scribed for the 810 nm wave- length. Under local anaesthesia, the non-initiated 320 μm ibre de- livered the energy at a distance of 2 mm to the pigmented area with constant movement. Immediate change to the pink colour without surface ablation of the pigmented mucosa was observed. The proce- dure took approximately 40 s to complete from the mandibular left to right canine region. In this case, the mucosa turned pink without any signs of surface mucosal ablation other than one spot between teeth #31 and 32 (Fig. 9). Subsurface coagula- 1 2 3 4 5 6 Fig. 1: Depigmentation by ablation.—Fig. 2: Depigmentation by absorption of melanin and haemoglobin.— Figs. 3–6: Depigmentation of upper arch: pre)op (Fig. 3), immediate coagulation (Fig. 4), three weeks post)op (Fig. 5), eight years post)op (Fig. 6).

Cosmetic Tribune Asia Pacific Edition

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