Cryosurgery by tetrafluoroethane: An answer to black gums.

To highlight the effect of 1,1,1,2 tetrafluoroethane (TFE), a new material for cryosurgery of gingival melanin pigmentation (GMP). Five patients were treated using a TFE-cooled swab and the pre- and post-treatment photographs were compared. Complete keratinization took place in 3-4 weeks after application without any trace of pigmentation. During the follow-up period, no side effects were observed and the improved esthetics were maintained upto 1 year.

INTRODUCTION

Oral melanin pigmentation is a frequently encountered clinical condition and has multifactorial etiology which includes genetic factors, tobacco use, drugs such as antimalarials and tricyclic antidepressants,[1] systemic disorders like Addison's disease,[2] endocrine disturbances, Albright's syndrome, malignant melanoma, Peutz-Jeghers syndrome,[3] trauma and other causes.

Smoking tobacco also induces the activation of melanocytes to produce melanin via noxious agents present in the smoke.[4] The colour of gingiva is determined by a number of factors, including the amount of keratinization, thickness of epithelium, size and number of blood vessels and the presence of various pigments. Melanin pigmentation often occurs on the gingiva as a result of excessive deposition of melanin. Melanocytes are primarily located in the basal and suprabasal layers of the epithelium. Active melanocytes convert tyrosine to melanin and is stored in the melanosomes and is transferred to the keratinocytes via them. The colour of pigmentation may vary from light brown to black depending upon the localization in the tissues and is dictated mainly by melanoblastic activity. Melanin pigmentation of the gingiva occurs in all races.[5]

Gingival hyperpigmentation is seen as a genetic trait in some populations and is more appropriately termed as physiologic or racial gingival pigmentation.[6] High levels of oral pigmentation are normally seen in African, East Asian, Mediterranean, and Hispanic populations.[7]

Although melanin pigmentation of the gingiva does not cause any medical problems, it is of esthetic concern for the conscious patient. Demand for cosmetic therapy is made, especially by fair skinned people with moderate or severe gingival pigmentation.[8] The colour of the gingiva that may cause esthetic concerns is an essential part of overall esthetics parallel to today's high cosmetic expectations.

Numerous techniques have been devised and used for the treatment of gingival hyperpigmentation such as gingivectomy,[9] free gingival grafts,[10] acellular dermal matrix,[11] laser therapy,[121314] and electrosurgery and gas expansion cryosurgery.[8] Laser surgery has become the treatment of choice as it improves hemostasis and causes less postoperative discomfort over scalpel surgery. Although cryosurgery does not require suturing or application of dressing as well as having the advantages of less/no post-operative bleeding and no scarring, it has not been used widely due to the expense of cryosurgery instruments and the safety concerns regarding storage of liquid gases.

Hence, a new material, a colourless, non inflammable gas, 1,1,1,2 tetrafluoroethane (TFE), used as a coolant for refrigerating systems and electronic circuits[4] and not having the disadvantages of frequently used cryogenic gases has been employed in this study. With a melting point of −101°C and a boiling point of −26°C, it is available in a pressurized spray can and immediately evaporate without residue following spraying.[4] Several human and animal toxicology studies have proved the material to be biocompatible with no oncogenic or genotoxic effect on animals.[1516] Since hypopigmentation has been reported as a side effect of cryosurgery,[17] the aim of this study is to evaluate the effectiveness of TFE in the treatment of gingival hyperpigmentation.

CASE REPORT

Five systemically and periodontally healthy patients with chief complaint of hyperpigmented gingiva were recruited from the Department of Periodontology, Dr. R. Ahmed Dental College and Hospital, Kolkata, for the study. The whole procedure and its effect were explained to the patients and a written informed consent was obtained from each of them prior to the study. Prior permission from the Institutional Ethical Committee was also obtained. A detailed medical history including smoking habit, systemic diseases associated or not associated with gingival melanin pigmentation, any malignancy, and medications was taken. Evaluation of any skin or perioral pigmentation was done and the gingival hyperpigmentation was carefully assessed.

Before application of TFE, the pigmented area was isolated and air dried Immediately after spraying, the temperature of the cotton applicator ranged from −46.7°C to −48°C.[4] Topical anesthesia with 2% lignocaine spray (lignocaine hydrochloride and adrenaline bitartarate injection, 2% with adrenaline 1 in 80,000, ICPA Health Products Ltd, 233A, Adarsh Indl. Estate, Sahar Road, Chakala, Andheri (East), Mumbai - 400 099, Maharashtra, India) was used to minimize discomfort [Figures 1 and 2]. TFE (134a, refrigerant for AC systems, contains 1.1.1.2-Tetrafluoroethane, DUPONT SUVA, DUPONT Fluorochemicals, Louisville Packaging Site, 7745, National Turnpike, Suite 190, Louisville, KY, USA 40214) was sprayed on a cotton swab and immediately rolled gently over the pigmented area and a freezing zone was continuously maintained in each area for about 30-40 s [Figures 3 and 4]. After the cryosurgical procedure, patients were examined at 1, 2, and 4 weeks [Figures 5 and 6] and subsequently after 1 year [Figure 7]. Digital photographs of the pigmented area were taken preoperatively and at each subsequent postoperative visit. [Figures 7 and 8]

Figure 1

Armamentarium

Figure 2

Pre-operative photograph

Figure 3

Freezing zones being maintained for 30-40s in the maxillary arch

Figure 4

Freezing zones being maintained for 30-40s in the mandibular arch

Figure 5

One week post-operative

Figure 6

4 weeks post-operative

Figure 7

Post-operative after 1 year

Figure 8

Pre and post-operative photographs of Case 2

RESULTS

Slight erythema of the gingiva developed immediately after the procedure. During the next 3-4 days, superficial necrosis became apparent and a whitish slough could be separated from the underlying tissue leaving a clean pink ulcer bed. The gingiva appeared normal within 1 week and epithelization was complete within 3-4 weeks of cryosurgical treatment. The patients did not suffer from any hemorrhage, infection, or any scar tissue formation. The initial healing was uneventful following TFE application, patient acceptance of the procedure was good, and only one patient complained of mild pain and discomfort.

The follow-up period was up to 1 year including clinical examination and photographic comparisons.

DISCUSSION

Melanin pigmentation of gingiva is common to all races. Melanin hyperpigmented gingiva can be an esthetic problem in many individuals especially if it is present on the facial aspect which can be seen during speech and smile, more so if gummy smile is present. In the present study, TFE was utilized for cryosurgical depigmentation of the gingiva. The postoperative period was uneventful and the depigmented gingiva became normal within 4 weeks. As shown previously, following epithelial destruction by cryosurgery, epithelial migration covered the denuded connective tissue and regenerated rapidly.[18] Cryosurgery is a technique that transfers heat from tissues and is commonly used in dermatological practice. The melanin is found in basal keratinocytes and subjacent macrophages, and destruction of subjacent cells is sufficient for depigmentation.[4] Minimum temperature needed for cell damage is cell specific, and melanocytes are very sensitive to low temperatures at −4°C to −7°C where cell death can occur.[17] Physical and chemical changes induced by freezing lead to cell destruction and cell death.[4] With TFE, a single session of cryosurgical treatment is usually sufficient to eliminate the pigmented area. The presence of any residual pigmentation may be diagnosed as early as 1 week postoperatively, and the procedure can be repeated to eliminate any residual pigmentation. Arikan[4] followed the patients through 30 months, including clinical examination and photographs, and reported no recurrence, with the exception of two patients who were heavy smokers (20 cigarettes/day), who had partial recurrence in small areas near the border of freezing zone at 24 and 30 months, respectively. Of all the techniques used for depigmentation of gingiva, laser surgery has become the treatment of choice but, it may not be used efficiently at the gingival margins and interdental papillary region due to close proximity to the tooth. This limitation may result in incomplete treatment and recurrence due to migration of melanocytes from the left-over area. However, Yeh[19] reported no repigmentation following cryosurgical treatment during a 2-year follow-up period. In the present study, TFE showed successful depigmentation with good patient compliance as the procedure was simple and effective and was well tolerated by all the patients. TFE cryosurgery is an inexpensive method. In addition, there was no post-operative bleeding and no scar formation. In this procedure, there is no need of anesthesia, sutures, and dressing which makes it superior to scalpel, laser, and other conventional procedures.

CONCLUSION

Cryosurgical depigmentation of gingiva by TFE is a novel method and can be used with minimum armamentarium and complications. However, to allow for its usage more commonly in routine dental practice, more studies with a large number of patients are warranted. It can be concluded within the limitations of this study that it is a safe, cost effective, and non-invasive method for the treatment of gingival melanin pigmentation.