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ePaper created 2016-10-11, 09:16:46 | version 1.38.0
Melanin depigmentation of gingiva using various laser wavelengths have been reported for over ten years.1–5 Layer by layer, the mucosa is ablated to the basal layer of the epithelium where the melanocytes are located. Lasers have been compared with the use of scalpel and diamond bur (Fig. 1).6–9 By incorporating the optical properties and absorption character- isticsof810nmtogetherwithspecific power parameters, a non ablative technique was developed (Fig. 2).10, 11 Another similar non-ablative technique described as microcoag- ulation was also reported using a 20 W 980 nm diode laser.12 The 445 nm blue wavelength was intro- duced in the dental market in 2015. By using 320 µm uninitiated fibre delivering 1 W continuous wave of 445 nm, the same non-ablative procedure and result can also be realized. Background with non-ablative technique Diode laser at 810 nm is poorly absorbed in water, but it is well ab- sorbed by pigment such as haemo- globin and melanin. The use of high power, short pulse duration concentrated the thermal energy on the surface over deep tissue thermal conduction with lower power and long pulse.13, 14 The au- thor has used the 810 nm wave- length (elexxion Claros 810 nm diode laser, elexxion AG, Singen, Germany) with the power parame- ters of 30 W, 20 kHz, 16 µs giving an average power of 10 W. Under local anaesthesia, a non-initiated 600 µm fibre was used. The fibre was placed at a distance of 2 mm to 5 mm from the pigmented mucosa. Coagulation can be observed with immediate effect upon irradiation. A constant movement must be per- formed in order to avoid thermal damage deep into the tissue. Water irrigation can be used as coolant during the treatment. There is no surface ablation of the pigmented mucosa but rather the haemoglobin and melanin absorbing the laser energy (Fig. 2). This technique (Figs. 3–6) showed a treatment time of two minutes compared to the ablative tech- nique time up to 30 minutes in an area of first premolar to first pre- molar of one dental arch. The wave- length of 445 nm is much better absorbed by melanin and haemo- globin than 810 nm (Fig. 7). Hence, a much lower power density may be used to produce the same effect. Case outline A 26-year-old female patient of Chinese ancestry presented with melanin pigmentation in 2007. Congenital melanin pigmentation of the labial gingiva was diag- nosed. Depigmentation on the upper arch using 810 nm at 30 W, 20 kHz, 16 µs was carried out. Eight years post-op showed mild relapse of pigmentation, but the patient was satisfied with the cos- metic appearance (Figs. 3–6). She now wanted the melanin pigment on her lower anterior segment to be removed (Fig. 8). Purpose Pigment removal in the re- quested sites was discussed using 445 nm diode laser. The same technique would be used and the patient consented to the treat- ment. Material and method SIROLaser Blue (Dentsply Sirona) with an emission wave- length of 445 nm was used at 1 W, CW delivered through a 320 µm fibre. Procedure Depigmentation technique is the same as described with the 810 nm wavelength (above). Under local anaesthesia, a non-initiated 320 µm fibre delivers the energy at a distance of 2 mm to the pig- mented area with constant move- ment. Immediate change to pink colour without surface ablation of the pigmented mucosa was ob- 10 Dental Tribune Asia Pacific Edition | 7+8/2016 TRENDS & APPLICATIONS Non-ablative melanin depigmentation By Dr Kenneth Luk, Hong Kong Figs. 8–11: Depigmentation of lower arch using 445 nm at 1 W CW, pre-op, immediate post-op, one day post-op and one day post-op laser peel between 31, 41.—Fig. 12: Three days post-op (photo taken by patient on holiday).—Fig. 13: Two weeks post-op. 8 9 11 12 10 13 Fig. 1: Depigmentation by ablation.—Fig. 2: Depigmentation by absorption of melanin and haemoglobin.—Figs. 3–6: Depigmentation on upper arch using 810 nm at 30 W, 20 kHz, 16 µs, pre-op, immediate coagulation, three weeks post-op and eight years post-op. Fig. 7: Absorption Spectra of biological materials. (Courtesy of J. Meister) 7 1 2 3 4 5 6 89 1112 12 3456