Clinical Advances in Periodontics — Vol. 2, No. 3, August 2012
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Comparative Evaluation Of Gingival Depigmentation By Diode Laser And Cryosurgery Using Tetrafluoroethane: 18-Month Follow-Up
Vishal Singh, Subraya Bhat Giliyar, Santhosh Kumar, Mahalinga Bhat

Introduction: Pigmentation of the gingiva is a negative factor in an otherwise acceptable “smile window.” Recently, cryosurgery and laser techniques have gained popularity for depigmentation and seem to be the most reliable and satisfactory procedures. To our knowledge, this case series is unique and is the first reporting comparison of cryosurgery and lasers in the literature.

Case Series: The study included 20 patients who presented with a chief complaint of “black gums” and requested cosmetic therapy. They were randomly divided into group A and group B of 10 patients each. Patients in group A were treated using a diode laser. The laser beam was set at 0.70 W power, 200 J energy, in continuous mode. Patients in group B were treated using tetrafluoroethane cryosurgery. Patients were followed for 3, 6, 12, and 18 months. Gingival depigmentation was assessed using a new index system, gingival pigmentation index, on the day of first depigmentation and at the end of 18 months. Patient satisfaction was evaluated by using a simple questionnaire. Both procedures were equally effective in depigmentation. At the 18-month follow-up, spotted repigmentation was found in one case in each group. Although there was initial healing discomfort and mild pain with cryosurgery, all the patients were satisfied with the esthetic outcomes.

Conclusion: During the 18-month follow-up, the depigmentation achieved using both the techniques was found equivalent and satisfactory. Clin Adv Periodontics 2012;2:129-134.

Key Words: Cryosurgery; esthetics; gingiva; hyperpigmentation; lasers.

Background

One of the important factors in the ‘‘smile window’’ is the color of the gingiva. Several factors determine the color, including increase or decrease in blood vessels, thickness of the epithelium, extent of keratinization, and endogenous and exogenous pigmentation.1

Physiologic pigmentation is symmetric, persistent, and does not alter the normal architecture, such as gingival stippling. 2 Gingival hyperpigmentation occurs as triangular/ linear/diffuse patches of dark brown to black or light brown to yellow color.3 Pigmentation may be seen at any age irrespective of sex, although it varies among different races and population.3

The first known study on oral pigmentation was performed by Adachi and Ramel3 in 1903. They noted dendritic cells containing pigments in the mucosa of the lower lip in white females. Melanin hyperpigmentation usually does not present a systemic problem, but individuals may complain of unesthetic black–brown gingiva. It may be considered a psychologic problem as well. Thus, depigmentation of the gingiva not only alters the esthetics1 but may also improve the patient’s self-image.

Several procedures have been historically used for gingival depigmentation. Although some procedures, such as chemical methods,4 are no longer in use, other methods, such as gingival abrasion5 and scalpel methods,6 have been applied with variable results. Cryosurgery6 and laser7 have been recognized as the most effective and reliable techniques, providing the highest patient satisfaction.

In recent years, cryosurgery,6 an effective method of tissue destruction by freezing, has become a therapeutic technique in medical and dental practice.8,9 Cryosurgery leads to cell destruction and tissue death attributable to physical and chemical changes induced by freezing. Most vital tissues are frozen at approximately 28C, and there is a total cell death at ultra-low temperature (below 208C).

There are various cryogens that are used in the cryosurgery. Tetrafluoroethane (TFE)9 is a newer, colorless, nonchlorofluorocarbon usually used as a coolant in refrigerating systems and electronic circuits. The safety of TFE has been proven in several human and animal toxicology studies. 9-12 It has a melting point of -1018C and a boiling point of -208C. It is commercially available as a pressurized spray can and immediately vaporizes without residue after spraying. It is used in endodontics for pulp testing.13,14 TFE is being used as a skin cooling medium in laser therapy in dermatology.11 Arikan and Gurkan12 reported successful results using TFE-cooled cotton swab application in cryosurgical gingival depigmentation.

Laser ablation, includingCO2 (10,600 nm),1 neodymiumdoped yttrium aluminum garnet laser (1,064 nm),1 erbiumdoped yttriumaluminum garnet laser (2,780 nm),1 anddiode laser (820 nm)15 has been used for gingival depigmentation.

The diode laser can be delivered through a flexible quartz fiber-optic handpiece and has a wavelength of 819 to 940 nm.15 The power output, which is generally z2 to 10 W, can be delivered in pulsed or continuousmode. It is absorbed by pigments in the soft tissue, thus making it an excellent hemostatic agent. Several studies have reported positive outcome after using the diode laser for depigmentation.6,15

The following study was undertaken to compare the effectiveness and long-term stability of diode laser and TFE cryosurgery for depigmentation in maxillary anterior sextants of ‘‘gummy smile’’ patients, who displayed mucogingival deformities and abnormal color around the teeth.16

Clinical Presentation

This study was conducted at the Department of Periodontology, Manipal College of Dental Sciences, Manipal University, Manipal, Karnataka, India. Twenty patients (aged 18 to 25 years old; eight males and 12 females) with the chief complaint of unesthetic gingival discoloration, in the maxillary anterior sextant were enrolled from April 2007 to April 2010. They were randomized by coin toss into group A (laser; n ¼ 10) or group B (TFE cryosurgery; n ¼ 10). Each group included four males and six females. Only patients with physiologic melanin hyperpigmentation were included. Exclusion criteria included: 1) pregnancy; 2) lactating; 3) systemic disease associated with pathologic gingival hyperpigmentation; 4) smoking; 5) uncontrolled diabetes; or 6) proven sensitivity or adverse reaction to cryosurgery. Relative contraindications were cold intolerance and cold urticaria. The study was performed in accordance with the Helsinki Declaration of 1975, as revised in 2000. The study protocol was reviewed and approved by the Institutional Ethics Committee, Kasturba Hospital, Manipal University. Each patient signed a written informed consent form. Before the gingival depigmentation, patients underwent full-mouth scaling, after which oral hygiene instructions were given. To assess the gingival pigmentation, the authors developed a new index system, the gingival pigmentation index (GPI) (Table 1). Gingival pigmentation was assessed preoperatively on the day of the first depigmentation procedure and at the end of 18 months. Patient satisfaction was assessed using a simple questionnaire (Fig. 1).

Clinical Management

Group A: Diode Laser

Before applying the laser, the operating staff and the patients wore special laser-protective glasses. Highly reflective instruments or instruments with mirrored surfaces were avoided.

The laser† was used at 0.70 to 1 W power, 200 J, in continuousmode. No topical or local anesthetic was used. Laser ablation was started from the mucogingival junction working toward the free gingival margin, including the papillae. Themotion of the ablation was circularwith overlapping circles. The procedure was completed within 20 to 25 minutes.

Group B: TFE Cryosurgery

Topical anesthesia with 10% xylocaine spray was used, to minimize the discomfort attributable tocooling.The TFE delivering device (Fig. 2) consisted of a TFE cylinder, with a spray-controlling nozzle at the tip. The nozzle was turned on so that ametered amount of spray was released. TFE was sprayed on a cotton swab and immediately rolled gently over the pigmented area. In each area, a freezing zone was continuously maintained for 30 to 40 seconds. The area from the maxillary right side canine to the left side canine was included. The time required varied from 20 to 25 minutes.

Follow-Up

For both groups, reinforcement of precautionary postoperative instructions, such as avoiding smoking and eating hot and spicy food for the first 24 hours, were given. Patients were prescribed analgesics as needed, if they experienced any pain.

All patients were recalled after 1 week and 3, 6, 12, and 18 months for postoperative observation. Standard digital photo images were obtained preoperatively and 18 months postoperatively. Pigmentation was assessed by direct clinical examination preoperatively and at 18 months postoperatively. Statistical analysis was done using c2 test (exact) (intergroup comparison).

Investigator Masking and Calibration

Gingival pigmentation was assessed by a single examiner (VS) who was masked to the treatment group to which a patient was assigned. The examiner evaluated 50 dental students showing pigmentation on two separate occasions 48 hours apart. Calibration was accepted if all the recordings could be reproduced with same scoring by the examiner.

Clinical Outcomes

Group A: Diode Laser

Immediately after the procedure, the area was covered with whitish slough in all the patients. No patient reported bleeding or pain. At 1 week, the treated site appeared pink and healthy, although in two cases, there were some spots of pigmentation. These cases were treated again by laser using the previous settings. At the 18-month follow-up, only one case showed spotted pigmentation (Fig. 3).

The GPI score at the day of depigmentation for all cases was 3. At the end of 18 months, a score of 0 was given for nine cases, because there was complete absence of pigmentation. The presence of spots of pigmentation in one case resulted in a score of 1 (Table 2).

Group B: TFE Cryosurgery

The treated area appeared red within 30 minutes after the procedure.Onday 1, tissue necrosis became evident, which was sloughed off from the underlying tissue in all the patients. There was no bleeding, but mild pain was reported by all patients. After 1 month, spotted pigmentation reappeared in two cases, which were treated by TFE again. After 18 months, only one case revealed spots of melanin pigmentation (Fig. 4).

The GPI score at the day of depigmentation for all cases was 3. At the end of 18 months, there was complete absence of pigmentation in nine cases, so a score of 0 was given. Because there were spots of pigmentation in one case, a score of 1 was given (Table 3).

At 18 months, comparative evaluation (statistical analysis using c2 test, exact) of both groups revealed similar results (Table 4).

Patient satisfaction was assessed using a simple questionnaire. Statistical assessment of patients response to each question was done (c2 test, exact). The mild pain and discomfort reported postoperatively inthe TFE group was statistically significant (P <0.001). However, all patients reported being esthetically satisfied.

Discussion

The additions of cryosurgery and laser ablation to the treatment armamentarium of gingival depigmentation have been found to be very useful and effective techniques. Often, cryosurgery has been applied with a gas expansion system that is expensive and cannot be used routinely in dental practice.6 Loss of gas attributable to leakage and evaporation and risk of accident (highly volatile) are other concerns. Cross-contamination is another disadvantageof cryosurgery, especially with the dipping method. TFE serves as an inexpensive, easy to store and transport cryogen.Ease of application with a cotton swab is another advantage.Absence of bleeding and only mild pain are added benefits.

Depigmentation with diode laser ablation procedure was found to be equally effective to TFE. Absence of pain during the procedure as well as postoperative period are obviously the key advantages of the laser method over the TFE method. In the present study, topical or local anesthetics were not used during laser ablation. Although analgesics were prescribed as needed, none of the patients reported taking them. Laser healing times observed in the present study were similar to the findings of other studies using the laser6,15,17 and were faster than TFE healing times. Photo biomodulation effects of laser helps instimulating the fibroblasts, angiogenesis, and accelerating the lymphatic flow, which enhances repair and regeneration. The bactericidal effect of the laser related to the generation of reactive oxygen species may also add to the faster healing in a relatively sterile environment.17

In the present study, repigmentation was observed in one case in each group, independent of the method used for the depigmentation. Pigmentation may reappear in some cases as a result of the presence of active melanocytes in the basal cell layer of the epithelium, which may not have been removed completely.18 It was reported that repigmentation may occur as a result of the application of chemicals.19 Certain chemicals, such as psoralens (methoxsalen), are reported to stimulate monocytes and produce melanin pigementation. 19 After laser depigmentation, repigmentation has been reported in four of 10 cases during a follow-up period of 2 years.1 Repigmentation observedmay also be attributable to spontaneous phenomena and may result because of migration of melanocytes from the surrounding tissues. Usually, the ultra-low temperature (-818C for 10 seconds) created by the cryosurgery technique results in complete epithelial destruction and elimination of the gingival epithelium along with the melanocytes. However, in some cases, active melanocytes may survive and become active again over time.6

Summary

Why are these cases new information?

To our knowledge, this case series is unique and is the first reported comparison of cryosurgery and laser for depigmentation of gingiva.

What are the keys to successful management of these cases?

These cases require patient recall after 1 week, observation, and, if necessary, depigmentation in some areas.

What are the primary limitations to success of these cases?

Follow-up evaluation at later periods may be required to evaluate accurately the time and reappearance of pigmentation, so that the timing of treatment of depigmentation can be established.

Acknowledgment

The authors report no conflicts of interest related to this case series.

References

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2. Dummett CO. Pertinent considerations in oral pigmentations. Br Dent J 1985;158:9-12.

3. Adachi B, Ramel A. The skin pigment in humans and in the monkey (in German). Z Morphol Anthropol 1903;6:1.

4. Hirschfeld I, Hirschfeld L. Oral pigmentation and a method of removing it. Oral Surg Oral Med Oral Pathol 1951;4:1012-1016.

5. Farnoosh AA. Treatment of gingival pigmentation and discoloration for esthetic purposes. Int J Periodontics Restorative Dent 1990;10: 312-319.

6. Tal H, Landsberg J, Kozlovsky A. Cryosurgical depigmentation of the gingiva. A case report. J Clin Periodontol 1987;14:614-617.

7. Azzeh MM. Treatment of gingval hyperpigmentation by erbium-doped: yttrium, aluminum, and garnet laser for esthetic purposes. J Periodontol 2007;78:177-184.

8. Freiman A, Bouganim N. History of cryotherapy. Dermatol Online J 2005;11:9.

9. Guan H, Zhao Z, He F, et al. The effects of different thawing temperatures on morphology and collagen metabolism of 20 degrees C dealt normal human fibroblast. Cryobiology 2007;55:52-59.

10. Alexander DJ, Libretto SE, Chevalier HJ, Imamura T, Pappritz G, Wilson J. HFA-134a (1,1,1,2-tetrafluoroethane); Lack of oncogenicity in rodents after inhalation. Hum Exp Toxicol 1995;14:706-714.

11. Bernstein EF. Severe urticaria after laser treatment for hair reduction. Dermatol Surg 2010;36:147-151.

12. Arikan F, Gurkan A. Cryosurgical treatment of gingival melanin pigmentation with tetrafluoroethane. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:452-457.

13. Jones DM. Effect of the type carrier used on the results of dichlorodifluoromethane application to teeth. J Endod 1999;25:692-694.

14. Miller SO, Johnson JD, Allemang JD, Strother JM. Cold testing through full-coverage restorations. J Endod 2004;30:695-700.

15. Lagdive S, Doshi Y, Marawar PP. Management of gingival hyperpigmentation using surgical blade and diode laser therapy: A comparative study. J Oral Laser Applications 2009;9:41-47.

16. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1-6.

17. Ohshiro T, Calderhead RG. Development of low reactive low level laser therapy and its presentation. J Clin Laser Med Surg 1991;9:267-275.

18. Ginwalla TM, Gomes BC, Varma BR. Surgical removal of gingival pigmentation (A preliminary study). J Indian Dent Assoc 1966;38:147- 150, passim.

19. Dummett CO, Bolden TE. Post-surgical clinical repigmentation of the gingivae. J Oral Surg Oral Med Oral Path 1963;16:353-365.

* Department of Periodontics, Manipal College of Dental Sciences, Manipal University, Manipal, Karnataka, India.

Submitted February 1, 2011; accepted for publication July 6, 2011

doi: 10.1902/cap.2012.110008
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