Abstract
Introduction:
Gingival melanin pigmentation is one of the most important factors for esthetically sensitive candidates. Literature reveals various depigmentation techniques which are predominantly utilized for clinical assessment only. The present randomized clinical study was planned to evaluate the efficacy of surgical stripping and diode laser-assisted gingival depigmentation techniques in terms of patient’s perspective, clinical, and histological outcome.
Materials and Methods:
Twenty patients with bilateral labial physiological gingival melanin pigmentation extended from the distal aspect of #13-23, 33-43 were selected as for the study. Dummet Oral Pigmentation Index (DOPI) and Hedin Melanin Index (HMI) were recorded, and incisional biopsies were taken at baseline to evaluate the density of melanin pigmentation. Both arches were equally treated by surgical stripping assisted gingival depigmentation and diode laser-assisted gingival depigmentation (SSAGD and DLAGD). Patients were re-evaluated at 3 and 6 months postoperatively for DOPI and HMI and at 6 months for the density of melanin pigmentation. Visual Analog Scale (VAS) was evaluated during surgery, 1st and 7th-day postoperatively. Data obtained were statistically analyzed using Wilcoxon Signed Ranks, Mann–Whitney U, Chi-square, and Student’s “t”- tests.
Results:
DOPI and HMI were reported to be statistically significant (P < 0.05) at different intervals and density of melanin pigmentation at 0–6 months intervals in both the groups on intragroup comparison. HMI and DMP were reported to be statistically significant at 6 months postoperatively and VAS during and 1-day postsurgery on intergroup comparison.
Conclusion:
SSAGD is best in terms of clinical and histological outcomes and induces less postoperative pain, and repigmentation is slow as compared to DLAGD.
Keywords: Density of melanin, diode laser, gingival depigmentation, gingival hyper melanin pigmentation, surgical stripping, visual analog scale
INTRODUCTION
Gingival hyper melanin pigmentation (GMP) is considered as one of the key issues that contribute a domineering role in facial esthetics. GMP may occur because of many factors such as systemic, genetic, environmental, postinflammatory factors, prolonged administration of certain drugs, Addison’s syndrome, and Peutz-jeghers syndrome.[1,2,3,4] In addition, gender, age, ethnicity, frequency of brushing, gingival biotype, and frequency of brushing will also influence the gingival color.[5]
Esthetically and smile cognizant aspirants with GMP regularly consulted the dentists to get riddance of the same to improve their smile and regain confidence. An extensive range of invasive, least invasive, and concealing gingival depigmentation procedures have been published in the world of literature; however, histological evaluation of the outcome and patient perceptions have not been explored. Therefore, the present randomized clinical study was planned to evaluate the efficacy of surgical stripping assisted gingival depigmentation and diode laser assisted gingival depigmentation (SSAGD and DLAGD) techniques, respectively, in terms of patient’s perspectives, clinical (extent and intensity of melanin pigmentation) and histological (density of melanin pigmentation) outcomes.
MATERIALS AND METHODS
The present randomized clinical and histological study was conducted in the institutional inpatient department of Periodontology, India, and executed as per the ethical standard outlined in the 1964 Declaration of Helsinki as revised in 2013, on receiving the due approval from the Institutional Ethical Committee.
A total of 20 periodontally and systemically healthy patients (11 females and 09 males with a mean age of 23.4 years) with 40 esthetic sites (20 maxillary and 20 mandibular) were randomly selected by lottery system [Table 1]. Informed written consent was signed by all the patients before initiation of the study.
Table 1.
CONSORT flow chart
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19–30 years periodontally and systemically patients of Sriganganagar and its surrounding districts in Rajasthan state. Patients having bilateral physiologic continuous band of gingival melanin pigmentation on the labial aspect extending from distal aspect of right canine to distal aspect of left canine in both the arches with Dummet Oral Pigmentation Index (DOPI) score 2–3 and Hedin Melanin Index (HMI) score 4 [Figure 1a] with 6–8 months of availability till study completion were the inclusion criterion. Smokers, pregnant and lactating mothers, patients with syndromes, debilitating diseases, genetic disorders, working in the metal industry, and suffering from periodontal disease, etc., were the exclusion criteria of the study.
Figure 1.
(a) Dummet Oral Pigmentation Index score 3 and Hedin Melanin Index score 4 both in maxillary and mandibular region respectively at baseline; (b and c) Hematoxylin and eosin-stained biopsy specimen taken at baseline from maxillary and mandibular region. Microphotographs showed dense but nonaggregated and dense and aggregated melanin granules respectively under ×10 magnification
In the present study, considering α =0.05, Power: 90%, β: 0.01, confidence interval: 85%, Coefficient of Variation: 17.5, and n = 14, considering the unknown error; the sample size was increased to 20 to compensate, if any of the patients drop out in between the study.
The intensity of melanin pigments score in all the selected patients were recorded utilizing DOPI stated score 0 – Pink-no pigmentation, 1 – light brown-mild pigmentation, 2 – mixed pink and brown pigmentation or medium brown, and 3 – deep brown or blackish, whereas extent of melanin pigments score were recorded utilizing HMI Score degree 1 – isolated only 1 or 2 pigmented interdental papilla, degree 2 numerous pigmented interdental papillae, degree 3 short continuous ribbons, and degree 4-long continuous ribbon respectively as baseline data and clinical photographs were taken [Figure 1a].
In addition, incisional partial thickness biopsy samples of approximately 4 mm were taken from both the arches by the principal investigator under 15% lidocaine topical application[6] to determine the density of melanin pigmentation at baseline, at least 4 weeks before treatment protocol. It also confirmed that patients are having negligible and bearable discomfort expressed as slight pain on the visual analog scale (VAS). The microphotographs of histological hematoxylin and eosin-stained section under ×10 magnification show para-keratinized stratified squamous epithelium with scattered but nonaggregated versus dense and aggregated melanin granules within the para-keratinized stratified squamous epithelium were observed in group I [Figure 1b] and II [Figure 1c] at baseline in the basal layers of the gingival epithelium. The underlying connective tissue stroma appears essentially normal with almost an absence of inflammatory cell infiltrate, respectively.
As all the selected patients were otherwise periodontally and systemically healthy with good oral hygiene maintenance, Phase I periodontal (Supragingival) therapy was carried out just before the GD procedure to reduce the supragingival microbial burden which may further influence the treatment outcome. Maxillary and mandibular arches were randomly allocated to SSAGD (Group I) and DLAGD (Group II) techniques utilizing sequentially numbered, opaque, sealed envelopes just before the initiation of the treatment phase by the trained clinician who was not part of the study, whereas both the surgeries were exclusively performed by the principal investigator.
After isolation and drying of labial gingival surface of selected site, 15% lidocaine local topical anesthetic solution was applied[6] for 10 min with gauze, and topical anesthesia was reapplied if the procedure is longer than 10 min.
In Group I: After achieving anesthesia, SSADG was carried out by gentle dissection of the gingival melanin pigmented epithelium, with a thin layer of underlying connective tissue was executed slowly and steadily utilizing 15 no. blade to minimize the trauma [Figure 2a and b]. Remnants of pigments and tissue tags were removed. After the entire depigmentation [Figure 2c] procedure, adequate hemostasis was achieved with a pressure pack.
Figure 2.
(a and b) Surgical stripping assisted gingival depigmentation (SSAGD) performed with surgical blade no. 15 in maxillary arch w.r.t #13-23; (c) Completion of SSAGD after hemostasis
In Group II: Followed by 940 nm DLAGD (Biolase Technology, Inc. of Irvine, CA) carried out at 2 Watt, in pulsed mode with a pulse interval of 20 ms and pulse length of 05 ms, initiated using 300 μm flexible fiber-optic hand piece tip after tip activation with initiator cork provided by manufacturer. The laser beam-assisted gingival epithelium ablation was carried out using 300 μm in focused (contact) mode using a light brushing stroke technique [Figure 3a and b] as described by Tal et al.,[7] from mucogingival junction toward the free marginal gingiva, including interdental papilla, in the presence of high-power vacuum suction, with intermittent wet gauze assisted cooling. All standardized safety measures were taken during DLAGD as per the manufacturer instructions. The procedure was continued till complete gingival depigmentation was achieved [Figure 3c]. Time duration taken to accomplish both the procedures was recorded.
Figure 3.
(a and b) Diode laser-assisted gingival depigmentation (DLAGD) performed with fiber-optic in contact mode and completion of DLAGD carbonization of gingival epithelium; (c) Gingival surface free from melanin pigmentation after removal of carbonized layer with wet gauze
Both procedures were performed on the same day with an average washout period of 1.5 h until the patient is completely comfortable to overcome any pain (VAS) if reported by the patient immediately after the first depigmentation procedure.
All the patients were asked to define the intensity of pain on a 10 cm horizontal continuous interval scale where the left end point was marked as “No Pain” and the right end point marked as “worst/severe pain” by using VAS and graded as 0 (no pain), 0.1–3 cm (slight pain), 3.1–6 cm (moderate pain), and 6.1–10 cm (severe pain) during surgery, 1 day and 1 week postoperatively.[6]
Oral hygiene instructions were given. Both SSAGD and DLAGD were performed on a single visit and were evaluated for the assessment of DOPI and HMI (clinically); immediately after procedure completion, and clinical photographs were taken at all follow-up intervals in both groups. Gingiva was free from signs of melanin and healed uneventfully at 7-days postoperatively in both sites. [Figure 4a] Mild melanin pigmentation observed in both treated sites but DLAGD treated mandibular site showed more pigmentation 3 months postoperatively. [Figure 4b] Dense colored melanin pigmentation was observed in both sites but scattered versus aggregated pigmentation pattern was observed in SSAGD versus DLAGD sites, respectively, 6 months postoperatively [Figure 4c].
Figure 4.
(a) Gingiva healed uneventfully at 7 days postoperatively in both sites; (b and c) Mild melanin pigmentation observed in both treated sites, but more in DLAGD treated mandibular site at 3 months. Dense but aggregated pigmentation was observed in DLAGD sites at 6 months postoperatively
Density of melanin pigmentation was reevaluated utilizing histological partial thickness biopsy specimens taken from both the groups 6 months postoperatively. The microphotographs of histological hematoxylin- and eosin-stained section under ×10 magnification represent parakeratinized stratified squamous epithelium with less dense but scattered melanin granules versus dense and aggregated melanin granules within the parakeratinized stratified squamous epithelium in the basal layers of epithelium in group I versus II, respectively. The underlying connective tissue stroma appears essentially normal with almost absence of inflammatory cell infiltrate 6 months postoperatively observed in Figure 5a versus Figure 5b, respectively.
Figure 5.
Hematoxylin and eosin-stained biopsy specimen taken 6 months postoperatively (a and b) arrows showed para-keratinized stratified squamous epithelium with less dense but scattered and dense and aggregated melanin granules in surgical and diode laser-assisted gingival depigmentation sites respectively under ×10 magnification
All the data were collected by the principal investigator and were subjected to statistical analysis utilizing Mann–Whitney U, Wilcoxon signed-ranks, and Chi-square tests along with Fisher’s Exact and Student’s “t”- test.
RESULTS
The mean intensity and extent of melanin pigmentation utilizing DOPI were score 3.0 ± 0.000, 0.15 ± 0.366, and 0.45 ± 0.510 and 3.0 ± 0.000, 0.3 ± 0.470, and 0.70 ± 0.470, for HMI score 4.00 ± 0.000, 0.35 ± 0.587, and 1.15 ± 1.089 and 4.00 ± 0.000, 0.55 ± 0.826, and 2.00 ± 1.10 at baseline, 3, and 6 months postoperatively for Groups I and II, respectively. Intensity and extent of melanin pigmentation on intragroup comparison were reported to be statistically significant at all intervals utilizing Wilcoxon signed-ranks test [Table 2] but nonsignificant (P > 0.05) on intergroup comparison at all intervals in terms of both intensity and extent of melanin pigmentation utilizing Mann–Whitney test except at 6 months postoperatively for HMI as reported in Table 3. The mean density of melanin pigmentation was score 3.00 ± 0.000 and 1.05 ± 0.686 and 3.00 ± 0.000 and 0.155 ± 0.605 at baseline and 6 months postoperative for Group I and II respectively.
Table 2.
Intra group comparison of Dummett oral pigmentation index and Hedin melanin index of Group I and Group II at different time intervals utilizing Wilcoxon signed ranks test
| Group | Descriptive analysis DOPI | Intragroup (DOPI) comparison between different time intervals | Descriptive analysis HMI | Intragroup (HMI) comparison between different time intervals | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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| Time | Mean±SD | Values | 0–3 month postoperative | 0–6 month postoperative | 3-6 months postoperative | Time | Mean±SD | Values | 0–3 month postoperative | 0–6 month postoperative | 3–6 month postoperative | |
| Group I (SSAGDl) 20 arches | Baseline (0) | 3.00±0.000 | Z | 4.234 (a) | 4.041 (a) | 2.449 (b) | Baseline (0) | 4.00±0.000 | Z | 4.093 (a) | 3.956 (a) | 3.025 (b) |
| 3 months postoperative | 0.15±0.366 | Asymptotic significant (two-tailed) P | <0.001** | <0.001** | 0.014* | 3 months postoperative | 0.35±0.587 | Asymptotic significant (two-tailed) P | <0.001** | <0.001** | 0.002** | |
| 6 months postoperative | 0.45±0.510 | 6 months postoperative | 1.15±1.089 | |||||||||
| Group II (DLAGD) 20 archess | Baseline (0) | 3.00±0.000 | Z | 4.099 (a) | 4.099 (a) | 2.828 (b) | Baseline (0) | 4.00±0.000 | Z | 4.056 (a) | 3.984 (a) | 3.453 (b) |
| 3 months postoperative | 0.30±0.470 | Asymptotic significant (two-tailed) P | <0.001** | <0.001** | 0.005** | 3 months postoperative | 0.55±0.826 | Asymptotic significant (two-tailed) P | <0.001** | <0.001** | 0.001** | |
| 6 months postoperative | 0.70±0.470 | 6 months postoperative | 2.00±1.170 | |||||||||
P>0.05 nonsignificant value; P<0.05 significant value. Z is coefficient of Wilcoxon sign test. DOPI - Dummett oral pigmentation index; HMI - Hedin melanin index, SD - Standard deviation; SSAGD - Surgical assisted gingival depigmentation; DLAGD - Diode laser assisted gingival depigmentation; Z – Test, P value – Probability value. *Statistically significant, **Highly statistically significant
Table 3.
Intergroup comparison of Dummett oral pigmentation index and Hedin melanin index at baseline, 3- and 6-month intervals utilizing Mann–Whitney U-test
| Intergroup comparison of DOPI | Intergroup comparison of HMI | |||||
|---|---|---|---|---|---|---|
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| Baseline | 3 months postoperative | 6 months postoperative | Baseline | 3 months postoperative | 6 months postoperative | |
| Mann–Whitney U | 200.000 | 170.000 | 150.000 | 200.000 | 181.500 | 119.500 |
| Wilcoxon W | 410.000 | 380.000 | 360.000 | 410.000 | 391.500 | 329.500 |
| Z | 0.000 | −1.122 | −1.579 | 0.000 | −0.606 | −2.258 |
| Asymptotic significant (two-tailed) P | 1.000 | 0.262 | 0.114 | 1.000 | 0.545 | 0.024* |
P>0.05 nonsignificant value; P<0.05 significant value. Z is coefficient of the Wilcoxon signed test. DOPI - Dummett oral pigmentation index; HMI - Hedin melanin index; Z – Z test. * - Statistically significant
Density of melanin pigmentation on intragroup comparison was reported to be statistically significant (P < 0.05) at 0–6 months and on intergroup comparison at 6 months postoperatively, utilizing interval utilizing Mann–Whitney test was reported in Table 4.
Table 4.
Intra and Inter group comparison of density of melanin pigmentation granules of Group I and Group II at different time interval utilizing Wilcoxon signed-rank test and Mann–Whitney U-test, respectively
| Group | Descriptive analysis of DMP | Intragroup comparison of DMP between different time intervals utilizing Wilcoxon signed-rank test | Intergroup comparison of DMP between group I and II utilizing Wilcoxon signed-rank test and Mann–Whitney U-test | ||||
|---|---|---|---|---|---|---|---|
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| Time | Mean±SD | Values | 0–6 months postoperative | Baseline | 6 month postoperative | ||
| Baseline (0) | 3.00±0.000 | Z | 4.008 | Mann–Whitney U | 200.000 | 121.500 | |
| Group I (SSAGDl) 20 arches | 6 months postoperative | 1.05±0.686 | Asymptotic significant (two-tailed) P | <0.001** | Wilcoxon W | 410.000 | 331.500 |
| Baseline (0) | 3.00±0.000 | Z | 4.042 | ||||
| Group II (DLAGD) 20 archess | 6 months postoperative | 1.55±0.605 | Asymptotic significant (two-tailed) P | <0.001** | Z | 0.000 | −2.330 |
| Asymptotic significant (two-tailed) P | 1.000 | 0.020* | |||||
P>0.05 nonsignificant value; P<0.05 significant value. Z is coefficient of Wilcoxon sign test. DMP - Density of melanin pigmentation granules; SSAGD - Surgical assisted gingival depigmentation; DLAGD - Diode laser-assisted gingival depigmentation; SD - Standard deviation; Z – Z test. * - Statistically significant. ** - Highly significant
Although repigmentation was observed in both the groups, SSAGD group has showed less repigmentation in comparison to the DLAGD group both clinically [Figure 4a-c] and on histological evaluation [Figure 5a and b), respectively.
The majority of the patients in group II experienced mild-to-moderate pain during and even 1 day postoperatively, whereas Group I patients experienced only mild pain, which was found to be statistically significant (P < 0.05) during and 1 day postsurgery on intergroup comparison [Table 5].
Table 5.
Intergroup comparison of Visual Analog Scale at respective intervals between group I and group II during surgery and 1 day postoperatively with utilizing Chi-square tests
| VAS | Groups during surgery | Total | Groups at 1 day postoperative | Total | Intergroup comparison during surgery utilizing Chi-square tests | Intergroup comparison at 1 day postutilizing Chi-square tests | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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| I | II | I | II | Value | Difference | Asymptotic significant (two-sided) | Value | Difference | Asymptotic significant (two-sided) | Exact significant (two-sided) | Exact significant (one-sided) | |||||
| No pain-0 | ||||||||||||||||
| Count | 11 | 2 | 13 | 18 | 6 | 24 | Pearson Chi-square | 15.231 (a) | 2 | <0.001** | Pearson Chi-square | 15.000 (b) | 1 | 0.000 | ||
| Percentage within group | 55.0 | 10.0 | 32.5 | 90.0 | 30.0 | 60.0 | Likelihood ratio | 19.336 | 2 | 0.000 | Continuity correction (a) | 12.604 | 1 | 0.000 | ||
| Slight pain-0.1–3 | ||||||||||||||||
| Count | 9 | 9 | 18 | 2 | 14 | 16 | Number of valid cases | 40 | - | - | Likelihood ratio | 16.403 | 1 | 0.000 | ||
| Moderate pain 3.1–6 | ||||||||||||||||
| Count | 0 | 9 | 9 | |||||||||||||
| Percentage within group | 0 | 45.0 | 22.5 | |||||||||||||
P>0.05 nonsignificant value; P<0.05 significant value. VAS - Visual Analog Scale. *- Statistically significant. **- Highly significant
Group II procedure took approximately half the time in comparison to Group I to accomplish the task despite a similar cooling period/isolation time of 5 min for both groups (Graph I). The mean difference in time was reported to be statistically significant (P < 0.05) on intergroup comparison utilizing Student’s “t”- test [Table 6].
Table 6.
Intergroup comparison of time consumed to accomplish both depigmentation procedures utilizing Student’s t-tests
| t-test for equality of means | |||||||
|---|---|---|---|---|---|---|---|
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| t | Difference | Significant (two-tailed) P | Mean difference | SE difference | 95% CI of the difference | ||
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| Lower | Upper | ||||||
| Time | 14.384 | 38 | 0.000 | 6.68917 | 0.46504 | 5.4774 | 7.63060 |
SE – Standard error; CI – Confidence interval; P – Probability value, t – t test
DISCUSSION
GMP is routinely encountered in the majority of patients visiting a dental practice irrespective of their nationality, creed, religion, social and financial status, etc. However, its intensity and extent may be variable. Keeping in mind the multifaceted etiology that might contribute to GMP; exclusively, the patients with physiological GMP were considered under the inclusion criterion and were treated in the present study.
Peutz–Jeghers syndrome is an autosomal dominant genetic disorder characterized by hamartomas of the alimentary canal and mucocutaneous melanin pigmentation spots observed intraorally majorly on buccal mucosa with black–brown in color, also seen on gingiva, lip, etc.[8] Postinflammatory pigmentation is excessive melanin production and deposition within the basal laser of epithelium and connective tissue in and around areas of chronic inflammation,[9] which appeared as black-to-brown pigment and varies from localized or diffused in character. It may even persist for many years or disappear after resolution of inflammation.[10] Smoker’s melanosis – Smoking induces oral pigmentation in light skin, whereas it increases the pigmentation in dark skinned patients.[11]
Occupational exposures to patients working in metal industries due to inhalation of heavy metal vapors.[12] Lead leads to gray pigmentation of the oral mucosa, silver amalgam leads to bluish–gray discoloration in oral mucosa.[13] Graphite tattoos are generally perplexed with amalgam tattoos, which can be differentially diagnosed, microscopically with the special staining. However, radiographically, silver tattoos may represent radio-opacity, but graphite is radiolucent.[14] Amalgam Tattoos commonly affect the gingiva, buccal mucosa of the mandible, and less on the maxillary region.[15]
The pathogenesis of drug-induced pigmentation depends on the causative drug being utilized by the patient. It can induce the accumulation of melanin, drug, or one of its metabolites, producing the pigments under the influence of the drug or deposition of iron after dermal vessel damage.[16]
Patients infected with human immunodeficiency virus presented with hyperpigmentation of the skin, oral mucosa, fingernails, etc., which have been reported to be linked with primary adrenocortical deficiency due to the azidothymidine therapy. In few cases, clinically oral pigmentation commonly affects buccal mucosa, tongue, and palate with brown/dark brown irregular macules.[17]
Tobacco is used worldwide in different forms. Gingival pigmentation in children has been associated with passive smoking from the adults of the family who smoke, or from the adults in surroundings. The intensity of pigmentation is more on the labial than on buccal mucosa as cited in the report of Sreeja et al.[13]
Therefore, most of above above-cited factors which may influence the melanin production/action either preoperatively or postoperatively were enlisted under the exclusion criterion. Although skin color and gingival pigmentation are associated with greater percentage of female have darker gums in comparison to males, other factors such as ethnicity,[18] oral hygiene practices and gingival biotype too impact the gingival pigmentation.[5] This might influence the outcome etc., that can be listed as few limitations of the study, in addition to the short term analysis on sample size.
Although extremely limited number of researchers evaluated the clinical and histological parameters following surgical and diode laser-assisted GD techniques, reports are still inconclusive because of the variable outcomes. Gul et al.[19] concluded that surgical stripping is considered as conventional treatment of choice, but suggested diode laser-assisted depigmentation was equally effective or even better. Although laser showed more regimentation at 6-month evaluation, Chandra et al.[20] suggested both surgical scalpel and diode laser techniques were clinically effective in the treatment of melanin pigmentation of gingiva, but keep in mind the cost, and armamentarium scalpel technique is the gold standard. D’Arcangelo et al. dictated that diode laser results were better than scalpel,[21] Hegde et al.[22] and Bakutra et al.[23] showed scalpel results were better than lasers, whereas Mani et al.[24] reported diode laser result was better than scalpel and bur abrasion, whereas Grover et al.,[25] Butchibabu et al.,[26] and Mahajan et al.[27] observed that diode and scalpel depigmentation techniques were equally efficient. That may be one of the other reasons why this study was planned and executed.
Both the techniques utilized in the present study were effective in reducing the extent and intensity of melanin pigmentation, which is in accordance with the studies of Hegde et al.,[22] Mani et al.,[24] Grover et al.,[25] Bhardwaj et al.,[28] Desai et al.[29] Thangavelu et al.[30] The results denoting the density of melanin pigmentation score up to 6-month follow-up is in accordance with the study by Hegde et al.[22]
On intergroup comparison, SSAGD showed better outcome in terms of reducing the extent and density of melanin pigmentation score, which is inconsistency with the reports of Hegde et al.,[22] Bakutra et al.,[23] and partially in favor of the reports of Grover et al.[25] and Butchibabu et al.[26] reported that both techniques were equally effective.
As melanin is a physiological endogenous pigment produced by the melanocytes, usually present in the basal and parabasal layers of the epithelium[31] and also in adjacent connective tissue layers too.[32] In consistency to these reports, dense and nonaggregated versus dense and aggregated melanin granules within the para-keratinized stratified squamous epithelium were observed in Groups I and II at baseline [Figure 1b and c] and scattered melanin granules versus dense, nonaggregated melanin granules within the para-keratinized stratified squamous epithelium in Groups I versus II [Figure 5a and b] observed 6 months postoperative, respectively, in the present study.
The overall outcome achieved in SSAGD may occur because it offered (i) better tactile sensation assisted gingival deepithelization, (ii) it not only removes the gingival epithelium but at the same time it partly includes the layer of connective tissue just apical to the epithelium, thereby eliminating most of the pigmented cells such as the melanophages or melanophores seated even in underlying connective tissue.[33] In addition, there is a possibility of a larger layer of cell death with scalpel technique which may help either in preventing migration effect of melanocytes,[27] or if any how have migrated they are not active during the healing period which may reduce melanocytes activity and thus reducing the recurrence of pigmentation.[34]
The overall outcome achieved in the DLAGD may be because 940 nm wavelength used in our study which (i) falls well within the absorption spectrum of the melanin pigment (351–1064 nm),[34] optimal absorption in melanin, hemoglobin and other pigments,[35] in addition to its minimal depth of penetration into the deeper tissue in comparison to the Nd: YAG laser, which has penetration capabilities of 4–6 mm tissue depth.[36]
The fast recurrence observed in DLAGD was in accordance with the report of Gul et al.[19] The reasons for the same may be because of different factors: (i) laser assisted epithelial ablation may not be able to remove all the melanocytes due to the presence of rete pegs in oral epithelium which may tends to repopulate and cause repigmentation,[4] (ii) photo-biomodulation effect of laser may accelerate the healing, and melanocytes from the adjacent area to migrate faster,[22] and (iii) heat energy generated during laser application may not able to influence few melanocytes seated deep in the connective tissue which may repopulate the surgical site.[37]
Although mild-to-moderate well-tolerated pain was reported in the groups, number of patients in the SSAGD reported slight pain in comparison with DLAGD group, which is in contrary to the reports of Grover et al. and Butchibabu et al., but they have performed the procedures under local anesthesia infiltration and evaluated VAS after 1 day,[25,26] respectively. Although the exact reason for the same is not conclusive, the possible reasons for the same may be either because of (i) treatment is provided under topical anesthesia, (ii) may be because diode laser-induced thermal effect after absorption of diode laser photons and temperature of soft tissue increased, second protein coagulation formed on deepithelized wound after diode laser was removed with wet gauze leaves a raw surface with exposed sensory nerve ending,[23] and (iii) patient pain threshold may be low in DLAGD.
Less time taken to accomplish the DLAGD procedure, which is in accordance with the study of Kasagani et al., but they utilized electrocautery-assisted depigmentation in comparison to scalpel scalpel-assisted depigmentation procedure.[38] The reason for the same may be because the diode laser exhibits the hot tip induced thermal effect accumulated at the working end of fiber, which when come in contact with treated tissue leads to induce a dense coagulation layer. The usage is quite like electro cauterization,[39] and without prompt bleeding, thereby providing a clear observation for left behind pigments removal at the earliest, which is routinely hampered in cases of SSAGD.
CONCLUSION
Within the limitations of study, it was concluded both the SSAGD and DLAGD techniques were effective in the management of gingival melanin pigmentation but in spite of invasive nature and bleeding tendency SSAGD still considered to have superior edge over the DLAGD when evaluated in term of pain experienced by the patient, extent of melanin pigmentation (clinically), and density of melanin pigmentation histologically other than cost of armamentarium.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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