Treatment of a Gingival Injury From a Cosmetic Laser Burn: A Case Report

In recent years a shift has occurred in dentistry whereby esthetics have garnered a higher priority than in the past. Patients' cosmetic expectations are ever increasing, thus gingival pigmentation, particularly that which is visible during smiling and talking, has become an important component of esthetics and an attractive smile.^1,2 Though gingival pigmentation occurs in all races, it is most frequently observed in dark-skinned populations,^3,4 and the gingiva is the most frequently pigmented intraoral tissue.³ Physiologic melanin pigmentation is relatively common in dark-skinned people, and usually the degree of gingival melanin pigmentation correlates well to the degree of melanin pigmentation of the skin.⁵ The most common etiology of pigments that contribute to the normal gingival color is melanin deposition by melanocytes, which, in turn, depends on the activity of the enzyme tyrosinase.^6,7

Due to the pandemicity of oral melanin pigmentation and today's high cosmetic demands, the topic of gingival pigmentation has gained considerable significance.^6,8 Gingival depigmentation is a periodontal plastic surgery in which the pigmented gingiva is removed. To date, several different techniques have been used for gingival depigmentation, including mechanical, surgical, electrosurgical, and cryosurgical methods; cauterization using chemical agents; gingival grafts; and lasers.^9-17 Scalpel surgery for depigmentation is a time-tested technique and remains the gold standard.^13,18

Lasers that are commonly used for gingival depigmentation are carbon dioxide (CO₂) (10,600 nm)¹⁴ and neodymium-doped yttrium aluminum garnet (Nd:YAG) (1,064 nm) lasers,⁹ though the erbium-doped yttrium aluminum garnet (Er:YAG) laser (2,940 nm) has attracted attention recently.¹⁰ Laser treatment removes the melanin pigment by ablating epithelial tissues. It requires that melanocytes are within the laser's range of penetration and contain melanin to absorb and convert light energy into heat via photothermolysis.¹⁹ The extent and time interval of recurrence varies with regard to the treatment modalities used. For depigmentation, while numerous modalities exist, laser is becoming the most effective, agreeable, and reliable technique and is associated with less morbidity than other techniques.^1,10,20

In the case reported herein, laser burn occurred as a result of misapplication during a depigmentation procedure. A review of reported laser incidents in the literature revealed the majority to be ocular injuries^21,22 or skin injuries.^23,24 Very few papers in the literature reported mucosal laser burns, and none reported laser burns associated with a gingival depigmentation procedure or discussed injury management.^25-29 To the author's knowledge, this is the first report of a case of gingival laser burn due to laser depigmentation and its management.

A 28-year-old female patient presented requesting cosmetic correction of recession and ulcerated gingiva with exposed bone in the right maxillary premolar area as a consequence of laser gingival depigmentation that was completed 2 months prior in a private practice. The patient stated that an unhealed denuded area appeared after the procedure and no improvement was seen in the following weeks. As a result, she decided to seek a second opinion at the Periodontology Department clinics at Faculty of Dentistry Hospital, King Abdulaziz University, Jeddah, Saudi Arabia.

Upon examination, a large elliptical ulceration was observed extending from the mesial aspect of tooth No. 3 to the mesial aspect of tooth No. 5 (Figure 1). The underlying alveolar bone was exposed and the surrounding gingival margins were inflamed. A corrective periodontal plastic surgical procedure was performed involving removal of the bony sequestrum, augmentation of the underlying bone layer, and reconstruction of the overlying soft tissues. Additionally, because of the delicate nature of the wound and the complexity of the subsequent repair, periodontal microsurgery techniques were used.

After local anesthesia was achieved, an intrasulcular incision was made that was limited to the buccal aspect of tooth No. 4 using a microsurgical blade (S-M Blade, Hartzell, denmat.com) (Figure 2). The edges of the wound were gently debrided using the same blade to create a fresh wound. A microsurgical periosteal elevator (Micro Elevator, Hartzell) was used to gently elevate the coronal gingival margin and create a pouch via blunt dissection (Figure 3 and Figure 4). The bony sequestrum was removed and the underlying alveolar bone was recontoured using a piezoelectric knife (Piezotome, Satelec Acteon, dental-bone-surgery.com) (Figure 5).

After promoting bony bleeding, 0.5 cc of demineralized freeze-dried bone (Ace Surgical Supply, acesurgical.com) was grafted to the site to cover the exposed bone and root dehiscence (Figure 6). A subepithelial connective tissue graft was harvested from the palate on the same side (Figure 7) and inserted under the gingival pouch and over the bone graft. The gingival graft was secured and the incision sutured with 6-0 chromic gut using sling and single interrupted sutures (Figure 8). After suturing the donor site (palate), the recipient site was protected with a periodontal dressing (COE-Pak^™, GC America, gcamerica.com).

The patient was sent home with prescriptions for an antibiotic (500 mg amoxicillin, three times daily for 7 days) to minimize the risk of infection and a nonsteroidal anti-inflammatory drug (400 mg ibuprofen) and was instructed to rinse with chlorhexidine twice a day for 2 weeks. The patient was followed-up weekly for the first 2 weeks (Figure 9 and Figure 10) and monthly after that until the third month. At the 3-month post-surgical visit, the repair appeared to have healed adequately at both the recipient and donor sites (Figure 11 and Figure 12), and the patient was pleased with the outcome.

The laser is a simple device that has revolutionized clinical practice. However, the diversity of laser technology in terms of different wavelengths, energy output modes, and setting parameters has resulted in a multiplicity of clinical protocols in general dentistry and in periodontology in particular. Given this diversity in types and usage, clinicians should utilize laser treatment only after acquiring a thorough understanding of the technology and how to properly use it in order to maximize benefits and minimize risk of injury.

The prognosis of laser depigmentation is generally favorable. As laser usage becomes more widespread and its application increasingly heterogeneous, the regulation of laser use and monitoring of laser safety are important, yet challenging, factors. Follow-up after laser treatment is essential, as all laser treatments come with inherent risks, including burns, and the treatment provider should be able to provide the required care.

Because not all lasers work exactly the same way, laser clinicians should be trained for each laser with which they work.^30,31 Ongoing education may also be beneficial. The laser practitioner must consider the type of laser being used and its indications, and understand the biophysics of the laser, the appropriate settings for the specific procedure, and how to intervene if complications occur. In the case reported herein, the patient was referred to the author's clinic and the author was unsure of the type of laser that had been used in the patient's prior treatment.

Giannelli et al studied the clinical efficacy of two different lasers for gingival depigmentation, a diode laser and an Er:YAG laser.³² They reported that the diode laser yielded better results. They also concluded that the Er:YAG laser should be used with caution, as it often resulted in incomplete ablation of the gingival epithelium with deeper epithelial ridges remaining in place, thus requiring repeated procedures, and, therefore, increasing the risk of damaging the lamina propria. Furthermore, it reportedly led to blood vessel dilatation that resulted in delayed wound healing. These and other reported findings confirm that the diode laser offers the advantages of safe and successful application in cases of gingival hyperpigmentation with minimal intraoperative and postoperative trauma.^33-36

The patient in the present case apparently experienced complications resulting from the improper use of a laser during gingival depigmentation and its management. Presumably, her injuries were unintended and her dentist did not deliberately do anything wrong. Fortunately, the oral mucosa heals remarkably well compared to skin fibroblasts. Histologically, oral mucosa fibroblasts are phenotypically different from skin fibroblasts and more closely resemble fetal fibroblasts (as gingival fibroblasts derived from the neural crest).³⁷ Such differences contribute to the rapid healing capacity of the oral mucosa.³⁸ Another reason for rapid healing is that the oral mucosa is continually covered with saliva, which contains a variety of growth factors and biologically active peptides and proteins. These substances promote tissue growth and differentiation, thus fostering wound healing.^38,39 Notably, however, if the injury is deep (eg, reaching the bone, as in the present case), debridement and grafting of the area would be indicated.

Another important element associated with disturbed wound healing is hypoxia.⁴⁰ Wounds must have a minimum oxygen tension of 30 mmHg for normal cell division and a minimum of 15 mmHg for fibroblast proliferation.⁴⁰ Hence, sufficient oxygenation is crucial for cell proliferation, angiogenesis, collagen synthesis, and re-epithelialization.^40,41 Therefore, in the present case, thorough debridement of necrotic bone to expose new intact healthy bone with neo-vascularization was mandatory to obtain a minimum oxygen tension and subsequent normal wound healing.^40,41

In addition to the presence of dead bone, another likely contributor to the chronicity and delayed healing in the present case was that the injury extended through the basement membrane to the underlying connective tissue and created necrosis of the bone. Because the main elements of the basement membrane include collagen type IV and adhesive molecules (laminins and fibronectin) that are important in fibroblast growth factor and vascular endothelial growth factor binding, they influence angiogenesis and accelerate the healing process.^42,43

To avoid complications, if a clinician is in doubt, it may be practical to use a longer wavelength with low fluence and/or high pulse duration.⁴⁴ This is based on the conservative principle that this allows the option to apply more intensive treatment subsequently, because once administered, treatment that was unduly intensive cannot be undone. Additionally, while all laser practitioners should take every precaution to prevent the occurrence of burns, they should also be aware of fundamental methods by which to address burns in the event that they do occur.

A primary obstacle while performing the surgery in the present case was achieving proper debridement of the necrotic bone, because within the confines of the small wound the author had to reach vital bone to provide a good blood supply to the subsequently added overlying graft. Clinically, in the maxilla or mandible, necrotic bone appears as white or yellowish painless denuded bone. However, in cases with a large area of necrotic bone, the area may exhibit secondary infection resulting in inflammation, pus formation, a foul odor, and greater pain.⁴⁵ Attempts to cover necrotic bone with local flaps or soft-tissue grafts often fail, leading to subsequent exposure of bone and the loss of overlying soft tissue.⁴⁶ In the present case, the surgery was performed with magnifying loupes, and the surgeon attempted to remove necrotic bone until vital bone was reached before suturing the graft. This was extremely difficult, however.

Potential complications can occur as a result of laser gingival depigmentation. Practitioners using lasers need to exercise utmost caution and understand how to prevent the type of injury reported herein. The risk of laser burns can never be completely eliminated however; thus, all laser practitioners should know the appropriate methods by which to address burns in the event that they do occur.

Maha A. Bahammam, BDS (Hons), MSc, DSc
Associate Professor, Chairman, Saudi Board in Periodontics - Western Region, and Program Director, Saudi Board in Periodontics, Department of Periodontology, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia