A 27-year-old male who had a chief complaint of unesthetic melanin pigmentation in the anterior part of the maxillary and mandibular gingiva visited the Department of Periodontology, School of Dentistry, Kyung Hee University. There was no remarkable medical history, but he had been smoking a pack of cigarettes per day on average for the last 10 years. Diffused melanin hyperpigmentation was found on the labial surface of both the maxillary and mandibular arches (Fig. 1).

For the comparison of the two techniques, melanin pigmentation was removed bilaterally: on the right side Er:YAG laser therapy was used, while on the other side the epithelium was mechanically removed with a rotary round bur.

The patient was treated with local anesthesia (lidocaine 2% with 1:80,000 epinephrine). The Er:YAG laser (KaVo KEY Laser, KaVo Dental GmbH, Biberach, Germany) was set at 250 mJ, 15 Hz and non-contact method. The handpiece tip was kept 10 mm away from the tissue in defocusing mode. The laser beam was activated using the 'brush technique,' as described by Tal et al. [17], with continuous movement of the beam overlapping the laser spots by approximately 20 to 30%. The laser was cautiously used to avoid injury to the tooth surface or adjacent tissues during the ablation. The papillary edges and free gingival margins were left untreated to decrease the risk of gingival recession.

A high speed handpiece and round carbide bur were used for abrasion on the other side. Abrasion under water spray over an epithelial layer was performed until whitish connective tissue was exposed. A # 2 round bur was used to draw the outline of the pigmented lesion and # 6 round bur was used for abrasion. All the melanin remnants of the epithelium were completely removed to prevent the possibility of recurrence (Fig. 2).

Upper jaw surgery was conducted 2 weeks prior to mandibular surgery. After surgery, the denuded connective tissue was covered with a periodontal pack. The procedure time was recorded on each quadrant and the visual analog scale (VAS) was also recorded to evaluate the subjective pain level. The VAS consisted of a horizontal line 100 mm long, anchored at the left end by the descriptor 'no pain' and at the other end by 'unbearable pain'. The patient was asked to mark the severity of the pain by him/herself. The distance between the left end to the point checked was recorded in millimeters and used as the VAS score. In addition, clinical parameters, such as wound healing, gingival color, pain, discomfort and tissue deformity, were recorded at 24 hours and 1, 2, 3 and 4 weeks after the procedure. The time spent on ablation of the gingiva by the Er:YAG laser was about 20 to 30 minutes on each quadrant, while that on abrasion with the rotary instruments was about 10 to 15 minutes.

One day after surgery, the patient reported slight pain on both sides with distinct irritation on the right side. Post-operative bleeding was not observed, and the connective tissue was still exposed with whitish sloughing (Fig. 3). After 1 week, neither side showed full epithelization, with slightly more advanced recovery on the left side, which had been treated with the rotary instruments (Fig. 4). After 2 weeks, re-epithelization was almost complete but had epithelium had not recovered its thickness yet (Fig. 5). After 4 weeks, the gingiva showed a normal appearance with pink color and keratinization (Fig. 6).

The patient was satisfied with the significant improvement in color. Tissue deformities, e.g., gingival recession and loss of papilla, were not observed after 4 weeks because the papillary edges and free gingival margins were left untreated. However, some pigments remained on the marginal gingiva and papillary area (Fig. 7).

A 32-year-old female who requested cosmetic therapy for "black gum" in the anterior part of the mandibular gingiva visited the Department of Periodontology, School of Dentistry, Kyung Hee University. There were no contributory medical problems. Melanin hyperpigmentation was found on the labial surface of the mandibular arches and maxillary lateral incisor. Compared with case 1, pigmentation showed more focal pigmented lesions (Fig. 8).

The same depigmentation techniques were applied: the Er:YAG laser on the right side and mechanical depigmentation of rotary round bur on the left side. Since the patient had focal pigmentation, depigmentation was conducted on both the maxilla and mandible area simultaneously. Due to the patient's thin gingival biotype and careless laser application, case 2 showed exposure of underlying bone around the incisal area on the right side of the mandible (Fig. 9).

At 1 week, the gingiva showed gradual epithelization, but was in an immature state. The laser surgery area showed redness and unfavorable healing with an appearance of necrosis. On the other hand, on the left side where the high speed rotary was applied, almost complete re-epithelization was observed (Fig. 10). After 2 weeks, epithelization was completed except in the right mandibular area (Fig. 11). A linear cleft was observed in the right mandibular area until 3 weeks. The wound healing was almost completed, but slight redness still remained at 4 weeks after surgery. However, the patient was satisfied with the significant improvement in color. Gingival recession and loss of papilla were not observed at 4 weeks after surgery (Fig. 12).