Quantitative analysis of gingival phenotype in different types of malocclusion in the anterior esthetic zone.

BACKGROUND: For any esthetic treatment planning, the shape and form of gingiva should be a prime factor of concern. The correct identification of gingival phenotype (GP) ensures a firm foundation for future health and prognosis of the treatment indicated. Hence, the aim of the present study was to evaluate the correlation between the GP in the anterior esthetic zone with different types of maloclussion and severity of crowding.
MATERIALS AND METHODS: A total of 110 periodontally healthy controls were equally divided into two groups depending on the type of malocclusion. They were further divided according to the levels of dental crowding as mild, moderate, and severe. GP was measured on the anterior esthetic teeth using transgingival probing, and width of the attached gingiva (WAG) was measured using histochemical staining method.
RESULTS: In severe crowding group, the GP in 12 and 22 region was found to be thick (P = 0.035) while, in 32 and 42 region was thin (P = 0.042). The WAG shows a significant difference between WAG with 23 in severe crowding group with P = 0.042, whereas there was no significant relationship found between the GP with Angle's classification.
CONCLUSION: Within the limitations of the study, it can be concluded that the teeth in the maxillary and mandibular anterior esthetic region showed the thin phenotype. When the severity of crowding increases, the GP and WAG vary depending on the position of the tooth. There is no association between the Angle's classification and the mean GP of the maxillary and mandibular anterior region teeth. Copyright:

INTRODUCTION

Reconstruction of esthetics is a challenge in today's dentistry for both clinicians and patients. The shape, size, and position of the teeth in a harmonious relation with the surrounding soft tissue are of prime concern for the esthetically pleasing smile. The compatibility of the surrounding soft tissue over hard tissue relies on numerous variables, one of which is the gingival phenotype (GP).[1] As we know, the most liable element of esthetic dentistry is the gingiva. The healthy gingival complex is necessary if the teeth are to be protected and positioned correctly. GP constitutes the degree of keratinization and results in the particular functional and esthetic characteristics of the individual.[23] The buccolingual thickness of the gingiva is termed as GP. According to the form and size of the root and contour of the alveolar bone, GP is classified as thick and thin.[45]

When the thickness of the gingiva is <1 mm, it is recognized as a thin phenotype, whereas when the thickness of gingiva is >1 mm, it is recognized as a thick phenotype.[6] The subtle thin GP is vulnerable to trauma, inflammation, and recession, whereas the thick GP being dense and fibrotic is generally considered to be the classical for periodontal health.[4]

Along with the GP, the width of the attached gingiva (WAG) is one of the most significant anatomical and functional landmarks of the periodontium.[7] An appropriate length of the attached gingiva enables to maintain esthetics and better control of the plaque. It is a component of the periodontal plastic and esthetic surgery to restore an appropriate WAG.[8] The need for orthodontic rehabilitation depends on the inclination and position of the teeth in the anterior esthetic zone.[4] Yared et al. 2006[9] reported that there was an increased risk of gingival recession after orthodontic treatment when the thickness of free gingival margin is < 0.5 mm, especially in cases of incisor proclination. There is a paucity of data available in existing literature assessing the association between GP and WAG with different types of malocclusion and severity of dental crowding. Hence, the aim of the present study was to evaluate the correlation between the GP in the maxillary and mandibular anterior esthetic zone with respect to malocclusion and severity of crowding.

MATERIALS AND METHODS

A total of 110 periodontally healthy patients (57 males, 53 females) with an age range of 18–30 years visiting the department of periodontics and implantology of our institute between December 2018 and May 2019 were enrolled in the study. The study was conducted in accordance with the Helsinki Declaration of 1975 revised in 2013 and approved by the Institutional Ethics Committee. The study protocol was explained to patients and written informed consent was obtained from them.

The sample size was calculated based on the study by Alkan et al. 2018.[10] The proportion of cases with severe crowding and with thick GP was 48%, while that in thin GP, it was 43%. Considering 95% confidence and 80% power, the sample size was found to be 110.

Inclusion criteria

Periodontally healthy patients

Patients with no systemic history

Patients with a complete set of permanent dentitions

Patients with no history or ongoing orthodontic treatment

Patients with Angle's Class I and Class II malocclusion with maxillary or mandibular anterior crowding.

Exclusion criteria

Presexisting periodontal disease

Congenital dental anomaly

Crowns or extensive restoration, especially in the maxillary or mandibular anterior region

Pregnant or lactating women

Any periodontal surgical procedure in the past 6 months

Patient taking medication known to affect the gingival condition or affecting mucogingival complex

Smokers.

According to the Angle's classification of malocclusion, the study population was divided into:

Group I: Angle's Class I malocclusion (n = 55)

Group 2: Angle's Class II malocclusion (n = 55).

The severity of dental crowding was assessed using model analysis. It was calculated by subtracting the mesiodistal width of the anterior tooth from the arch perimeter.

Depending on the Little's Irregularity Index, it was divided into three types: mild crowding (0–3 mm), moderate crowding (4–6 mm), and severe crowding group (>6 mm).

Depending on the severity of crowding, the study group was further subdivided as mild, moderate, and severe crowding.

Clinical examination

The intraoral examination was conducted by a single examiner. The clinical parameters measured included plaque index (PI) by Silness and Loe in 1964, gingival index (GI) by Loe and Silness in 1963, and probing pocket depth (PPD) using a manual periodontal probe with UNC #15 Hu Friedy Chicago, IL.

GP was measured by a transgingival probing method. Topical anesthetic spray was applied. The gingival thickness of each tooth was measured by piercing the soft tissue perpendicular to the long axis of the tooth using a 10 mm endodontic file with a rubber stopper until the alveolar bone is reached. All measurements were repeated two times at 10-min intervals, and the average result was recorded as the final measurement for thickness at each location [Figure 1].[10]

Figure 1

Gingival phenotype measurement by transgingival probing

Measurement of the width of the attached gingiva

Keratinized gingival width was measured from the free gingival margin to the mucogingival junction on the labial aspect of teeth using visual method after histochemical staining with '”Lugol's iodine Solution.” The Lugol's iodine solution was prepared by diluting 2 g of potassium iodide and 1 g of iodine crystals in 60 ml of distilled water.[11] The solution was applied to patient's gingiva and alveolar mucosa using cotton pellet and light pressure.

Statistical analysis

The data were collected and analyzed using SPSS version 20.0 software (IBM Corporation, New York, USA). The descriptive statistics were expressed in the form of mean and standard deviation for GP, WAG, PI, GI, and PPD. The distribution of patients according to the Angle's classification and severity of crowding was obtained by Chi-square test. The PI, GI, and PD measurements according to the Angle's classification and severity of crowding were obtained by analysis of variance (ANOVA) test. The correlation between GP and WAG in both the groups was also calculated using the ANOVA test. Likewise, Shapiro–Wilks test was used to determine the normality of data. Levene's test was used to test the differences of variances. The intraclass correlation coefficient for continuous variables was calculated by ± 3 sigma limits which were used to determine any outliers in the data set.

RESULTS

The percentage distribution according to the Angle's classification and severity of crowding in the maxillary and mandibular arch is displayed in Table 1.

Table 1

Distribution of patients according to the Angle’s classification and amount of crowding

Arch	Classification	Amount of crowding			P*
		Mild, n (%)	Moderate, n (%)	Severe, n (%)
Maxillary	Angle Class I	7 (43.75)	7 (41.17)	12 (48)	0.8883 (NS)
	Angle Class II	9 (56.25)	10 (58.82)	13 (52)
Mandibular	Angle Class I	8 (61.54)	10 (55.55)	11 (52.38)	0.9179 (NS)
	Angle Class II	5 (38.46)	8 (44.44)	10 (47.61)

P<0.05 statistically significant. *Obtained using Chi-square test. NS – Not significant; P – Probability of occurrence; n – Number of patient expressed as percentage

Table 2 depicts the mean gender-wise distribution according to the Angle's classification and amount of crowding in both the arches. There were no statistically significant differences in terms of the gender of patients in malocclusion and severity of crowding.

Table 2

Gender-wise distribution according to the Angle’s classification and amount of crowding

Classification	Amount of crowding	Female		Male		Total
		Maxillary, n (%)	Mandibular, n (%)	Maxillary, n (%)	Mandibular, n (%)	Maxillary, n (%)	Mandibular, n (%)
Class I	Mild	2 (8.33)	6 (20.68)	4 (11.76)	2 (8.69)	7 (12.06)	8 (15.38)
	Moderate	3 (12.5)	4 (13.79)	4 (11.76)	6 (26.08)	7 (12.06)	10 (19.23)
	Severe	6 (25)	6 (20.68)	7 (20.58)	5 (21.73)	12 (20.68)	11 (21.15)
Class II	Mild	4 (16.66)	3 (10.34)	5 (14.70)	2 (8.69)	9 (15.51)	5 (9.61)
	Moderate	4 (16.66)	4 (13.79)	6 (17.64)	4 (17.39)	10 (17.24)	8 (15.38)
	Severe	5 (20.83)	6 (20.68)	8 (23.52)	4 (17.39)	13 (22.41)	10 (19.23)

n – Number of patient expressed as percentage

Table 3 displays the mean PI, GI, and PD measurements according to the Angle's classification and severity of crowding in both the arches and shows that in the maxillary arch, the mean PD values for severe crowding showed a statistically significant difference between two classes with P = 0.022, whereas in the mandibular arch, in cases of Class I malocclusion, the mean PI values were higher in severe crowding as compared to mild and moderate crowding, which showed a statistically significant difference with P < 0.0001. The overall mean also showed a significant difference with P = 0.011. Furthermore, the mean PI for moderate and severe crowding showed a statistically significant difference with P < 0.0001 and 0.040, respectively, between the two classes. The overall means also showed a statistically significant difference between the two classes with P = 0.012.

Table 3

Descriptive statistics of plaque index, gingival index, and probing depth measurements according to the Angle’s classification and amount of crowding

Parameters	Mean±SD				P*
	Mild crowding	Moderate crowding	Severe crowding	Total
PI
Maxillary
Class I	0.57±0.09	0.54±0.13	0.65±0.14	0.58±0.13	0.074
Class II	0.53±0.09	0.58±0.12	0.60±0.11	0.57±0.11	0.372
Total	0.55±0.09	0.55±0.13	0.63±0.13	0.58±0.12	0.059
P	0.304	0.404	0.419	0.611
Mandibular
Class I	0.68±0.20	0.67±0.09	1.12±0.17	0.82±0.26	<0.0001
Class II	0.94±0.34	1.10±0.23	0.92±0.19	1.01±0.25	0.306
Total	0.78±0.28	0.85±0.27	1.05±0.20	0.89±0.27	0.011
PŦ	0.106	<0.0001	0.040	0.012
GI
Maxillary
Class I	1.16±0.20	1.08±0.25	1.06±0.19	1.10±0.21	0.485
Class II	1.19±0.19	1.23±0.29	1.00±0.32	1.15±0.28	0.176
Total	1.18±0.19	1.14±0.27	1.04±0.24	1.12±0.24	0.147
P	0.756	0.192	0.603	0.424
Mandibular
Class I	0.75±0.27	1.03±0.26	0.51±0.10	0.79±0.31	<0.0001
Class II	0.66±0.05	0.56±0.13	0.52±0.12	0.57±0.12	0.145
Total	0.72±0.22	0.83±0.32	0.51±0.11	0.70±0.27	0.001
PŦ	0.488	<0.0001	0.893	0.004
PPD
Maxillary
Class I	1.37±0.25	1.46±0.37	1.57±0.15	1.47±0.28	0.239
Class II	1.40±0.19	1.34±0.13	1.39±0.18	1.38±0.17	0.709
Total	1.39±0.22	1.41±0.30	1.50±0.19	1.43±0.24	0.302
P	0.784	0.325	0.022	0.102
Mandibular
Class I	1.55±0.39	1.48±0.24	1.25±0.13	1.42±0.28	0.031
Class II	1.38±0.13	1.44±0.28	1.33±0.10	1.40±0.21	0.618
Total	1.48±0.32	1.46±0.25	1.28±0.13	1.40±0.25	0.028
PŦ	0.372	0.720	0.174	0.748

P<0.05 statistically significant. *Obtained using analysis of variance; ŦObtained using independent t-test; Bold values: Significant. SD – Standard deviation; PI – Plaque index; GI – Gingival index; PPD – Probing pocket depth; P – Probability of occurrence

The mean GI values in Class I malocclusion in the mandibular arch were higher in moderate crowding as compared to mild and severe crowding, which showed a statistically significant difference with P < 0.0001. The overall mean also showed a significant difference with P = 0.001. The mean GI values for moderate crowding showed a statistically significant difference with P < 0.0001 between the two classes. The overall mean also showed a statistically significant difference between the two classes with P = 0.004.

PD values were higher in mild crowding as compared to moderate and severe crowding, which showed a statistically significant mean difference in Class I category with P < 0.0001. The overall mean also showed a statistically significant difference with P = 0.028.

Table 4 summarizes and displays the mean GP of the maxillary and mandibular anterior teeth on the basis of Angle's classification and the severity of crowding, respectively. In the maxillary arch, the mean GP of anterior tooth number 12, in severe crowding category, showed a statistically significant difference between the two classes with P = 0.046. Further, the mean GP of anterior tooth number 22, in moderate and severe crowding categories, showed a statistically significant difference with P = 0.035 each, whereas in the case of the mandibular arch, the mean GP of anterior tooth 42 and 32 with severe crowding showed a statistically significant difference between the two classes with P = 0.034 and 0.020, respectively.

Table 4

Gingival phenotype of mandibular anterior teeth according to the Angle’s classification and amount of crowding

GP of tooth	Malocclusion	Mean±SD				P*
		Mild crowding	Moderate crowding	Severe crowding	Total
11	Class I	1.10±0.33	1.01±0.26	1.08±0.19	1.06±0.26	0.694
	Class II	1.04±0.23	0.82±0.23	1.06±0.24	0.97±0.25	0.057
	Total	1.07±0.28	0.93±0.26	1.07±0.21	1.02±0.26	0.110
	P	0.636	0.072	0.817	0.148
12	Class I	1.05±0.24	1.04±0.28	1.06±0.20	1.04±0.25	0.980
	Class II	1.01±0.22	0.81±0.26	0.88±0.17	0.98±0.26	0.145
	Total	1.03±0.23	0.95±0.29	1.06±0.23	1.01±0.25	0.287
	P	0.667	0.050	0.046	0.334
13	Class I	0.93±0.16	0.86±0.24	0.93±0.30	0.91±0.24	0.733
	Class II	0.93±0.29	0.78±0.22	0.97±0.37	0.89±0.30	0.356
	Total	0.93±0.22	0.83±0.23	0.95±0.32	0.90±0.26	0.274
	P	0.979	0.394	0.804	0.813
21	Class I	1.06±0.30	0.99±0.21	1.05±0.20	1.03±0.23	0.736
	Class II	1.01±0.23	0.83±0.16	1.01±0.18	0.95±0.20	0.073
	Total	1.04±0.27	0.93±0.20	1.03±0.19	1.00±0.22	0.156
	P	0.658	0.050	0.679	0.13
22	Class I	1.03±0.30	1.03±0.28	1.04±0.22	1.02±0.26	0.993
	Class II	1.01±0.26	0.77±0.28	0.87±0.05	0.96±0.28	0.073
	Total	1.02±0.27	0.92±0.30	1.05±0.23	1.00±0.27	0.227
	P	0.889	0.035	0.035	0.337
23	Class I	0.98±0.17	0.88±0.32	0.98±0.28	0.94±0.27	0.516
	Class II	0.96±0.30	0.84±0.23	0.96±0.30	0.92±0.27	0.562
	Total	0.97±0.23	0.86±0.28	0.97±0.28	0.93±0.27	0.276
	PŦ	0.836	0.747	0.818	0.680
31	Class I	0.64±0.23	0.85±0.29	0.83±0.26	0.79±0.26	0.194
	Class II	0.72±0.29	0.76±0.33	0.95±0.29	0.80±0.30	0.405
	Total	0.66±0.24	0.81±0.30	0.87±0.27	0.80±0.27	0.151
	PŦ	0.580	0.487	0.390	0.860
32	Class I	0.75±0.33	0.83±0.24	0.90±0.27	0.84±0.27	0.493
	Class II	0.74±0.18	0.84±0.35	0.72±0.28	0.81±0.29	0.264
	Total	0.75±0.27	0.83±0.29	0.79±0.27	0.83±0.27	0.417
	PŦ	0.951	0.925	0.020	0.700
33	Class I	0.66±0.29	0.86±0.32	0.67±0.34	0.75±0.32	0.257
	Class II	0.82±0.19	0.73±0.35	0.83±0.36	0.78±0.31	0.790
	Total	0.72±0.26	0.8±0.33	0.73±0.34	0.76±0.31	0.676
	PŦ	0.305	0.362	0.375	0.716
41	Class I	0.68±0.29	0.96±0.21	0.84±0.28	0.85±0.27	0.057
	Class II	0.76±0.23	0.74±0.34	0.92±0.29	0.79±0.29	0.521
	Total	0.71±0.26	0.87±0.29	0.86±0.28	0.83±0.28	0.211
	PŦ	0.588	0.070	0.580	0.500
42	Class I	0.79±0.27	0.87±0.27	0.92±0.24	0.87±0.27	0.568
	Class II	0.86±0.19	0.82±0.33	0.63±0.23	0.82±0.26	0.937
	Total	0.81±0.24	0.85±0.29	0.82±0.27	0.85±0.27	0.725
	PŦ	0.614	0.679	0.034	0.490
43	Class I	0.71±0.28	0.94±0.26	0.69±0.34	0.80±0.31	0.086
	Class II	0.92±0.15	0.73±0.35	0.83±0.36	0.80±0.31	0.545
	Total	0.79±0.25	0.85±0.31	0.74±0.34	0.80±0.31	0.535
	PŦ	0.159	0.108	0.428	0.956

P<0.05 statistically significant. *Obtained using analysis of variance; ŦObtained using independent t-test; Bold values: Significant. GP – Gingival phenotype; SD – Standard deviation; P – Probability of occurrence

Table 5 displays the mean WAG of the maxillary and mandibular anterior teeth according to the Angle's classification and the severity of crowding. In the maxillary arch, the mean WAG of anterior tooth number 23, in moderate crowding category, showed a statistically significant difference between the two classes with P = 0.042. The mean WAG of anterior tooth number 22, in moderate crowding category, showed a statistically significant difference between classes with P = 0.009. Furthermore, for Class II, the mean WAG showed a statistically significant difference across crowding categories with P = 0.007.

Table 5

Width of the attached gingiva of the mandibular anterior teeth according to the Angle’s classification and amount of crowding

WAG of the tooth	Malocclusion	Mild crowding	Moderate crowding	Severe crowding	Total	P*
11	Class I	3.11±0.56	2.28±0.27	2.48±0.38	2.59±0.53	<0.0001
	Class II	2.40±0.33	2.52±0.32	2.16±0.11	2.37±0.31	0.025
	Total	2.77±0.58	2.38±0.31	2.35±0.34	2.49±0.46	0.002
	P	0.002	0.047	0.020	0.045
12	Class I	2.81±0.46	2.75±0.36	2.74±0.45	2.76±0.41	0.910
	Class II	2.92±0.37	2.34±0.32	2.74±0.46	2.67±0.45	0.007
	Total	2.86±0.41	2.58±0.39	2.74±0.44	2.72±0.43	0.081
	P	0.554	0.009	0.976	0.357
13	Class I	2.27±0.28	2.36±0.31	2.45±0.24	2.37±0.28	0.300
	Class II	2.36±0.38	2.65±0.35	2.31±0.20	2.44±0.35	0.061
	Total	2.31±0.33	2.48±0.35	2.40±0.23	2.40±0.31	0.212
	P	0.554	0.042	0.165	0.308
21	Class I	3.05±0.56	2.34±0.33	2.50±0.49	2.60±0.54	0.001
	Class II	2.44±0.26	2.52±0.32	2.19±0.13	2.39±0.28	0.023
	Total	2.76±0.53	2.41±0.33	2.37±0.41	2.51±0.46	0.007
	P	0.005	0.183	0.079	0.061
22	Class I	2.82±0.56	2.79±0.44	2.88±0.38	2.83±0.45	0.873
	Class II	2.99±0.28	2.44±0.44	2.77±0.48	2.73±0.46	0.019
	Total	2.90±0.45	2.64±0.46	2.83±0.42	2.79±0.45	0.132
	P	0.393	0.069	0.556	0.395
23	Class I	2.75±0.70	2.42±0.38	2.54±0.42	2.56±0.51	0.291
	Class II	2.47±0.34	2.36±0.40	2.59±0.47	2.47±0.40	0.480
	Total	2.61±0.57	2.40±0.38	2.56±0.43	2.52±0.46	0.258
	P	0.276	0.707	0.794	0.455
31	Class I	1.41±0.17	1.79±0.27	1.53±0.33	1.60±0.31	0.009
	Class II	1.22±0.22	1.58±0.32	1.48±0.34	1.46±0.32	0.125
	Total	1.33±0.21	1.70±0.30	1.51±0.33	1.55±0.32	0.002
	PŦ	0.103	0.099	0.800	0.112
32	Class I	2.09±0.24	2.19±0.51	1.99±0.42	2.10±0.43	0.515
	Class II	1.66±0.26	1.83±0.35	1.62±0.33	1.72±0.33	0.408
	Total	1.92±0.32	2.04±0.48	1.85±0.42	1.95±0.43	0.392
	PŦ	0.012	0.067	0.078	0.001
33	Class I	1.50±0.19	1.46±0.23	1.26±0.12	1.41±0.21	0.016
	Class II	1.76±0.32	1.42±0.44	1.53±0.34	1.53±0.39	0.306
	Total	1.60±0.27	1.44±0.32	1.36±0.25	1.45±0.29	0.088
	PŦ	0.092	0.751	0.028	0.129
41	Class I	1.46±0.14	1.93±0.14	1.69±0.47	1.73±0.34	0.004
	Class II	1.70±0.39	1.57±0.34	1.47±0.34	1.57±0.35	0.560
	Total	1.55±0.28	1.77±0.29	1.61±0.43	1.67±0.35	0.119
	PŦ	0.141	0.002	0.323	0.091
42	Class I	2.03±0.24	2.11±0.43	1.85±0.25	2.00±0.35	0.171
	Class II	1.52±0.24	1.80±0.31	1.62±0.40	1.68±0.33	0.264
	Total	1.83±0.34	1.98±0.41	1.76±0.32	1.87±0.37	0.168
	PŦ	0.004	0.660	0.163	0.001
43	Class I	1.45±0.24	2.16±0.31	1.26±0.17	1.68±0.48	<0.0001
	Class II	1.82±0.26	1.25±0.29	1.77±0.55	1.53±0.45	0.014
	Total	1.59±0.3	1.77±0.54	1.44±0.42	1.63±0.47	0.073
	PŦ	0.023	<0.0001	0.012	0.246

P<0.05 statistically significant. *Obtained using analysis of variance; ŦObtained using independent t-test; Bold values: Significant. WAG – Width of the attached gingiva; SD – Standard deviation; P – Probability of occurrence

The mean WAG of anterior tooth number 21, for both the classes, showed a statistically significant difference across crowding categories with P values <0.0001 and 0.025, respectively. Furthermore, the overall mean WAG was significantly different between two classes for mild, moderate, and severe crowding categories with P = 0.002, 0.047, and 0.02, respectively. The mean WAG of anterior tooth number 11, in the mild category, showed a statistically significant difference between classes with P = 0.005. For Classes I and II, the mean WAG was significantly different across crowding severities with P = 0.001 and 0.023, respectively. The mean WAG of anterior tooth number 12, for Class II category, showed a statistically significant difference across crowding severities with P = 0.019, whereas in the mandibular arch, the mean WAG of anterior tooth number 43 showed a statistically significant difference between the two classes for mild, moderate, and severe crowding with P = 0.023, <0.0001, and 0.012, respectively. For Classes I and II malocclusion, the mean WAG for severe crowding group shows a statistically significant result with P < 0.0001 and 0.014, respectively. For mild crowding group, the WAG of tooth number 42 showed statistically significant between Class I and Class II groups with P = 0.004. For moderate crowding group, the mean WAG of tooth number 41 showed a statistically significant result between Class I and Class II groups with P = 0.002. Furthermore, the overall mean WAG across the severity of crowding showed a statistically significant difference with P = 0.002.

DISCUSSION

For any esthetic treatment planning, the shape and form of gingiva should be a prime factor of concern.[12] In terms of esthetics, the ultimate goal is to achieve the complete harmony and balance of the hard tissue with the surrounding soft tissue. Especially in the anterior esthetic zone, numerous risk factors such as the age of the patient, the periodontal health, the treatment duration, the amount and type of tooth movement, the WAG and the GP, tooth position, and inclination are known to cause gingival recession.[1314] Hence, while determining the amount of protrusion, the biological factors such as GP, WAG, and the periodontal status should be taken into consideration.

Wennström et al. 1987[11] and Yared et al. 2006[9] specified that the parameters which should be preliminary understood are GP and WAG being a remarkable risk factor for the gingival recession in orthodontic treatment. Thus, taking this into account, the present study was formulated to evaluate and compare GP and WAG in different types of malocclusion and crowding severity in the anterior esthetic region.

The morphological character of the gingiva plays a crucial role in achieving the pink esthetic. The factors such as the dimension of alveolar process, the form of teeth, tooth eruption events, and eventually, the position and inclination of fully erupted teeth determine the GP.

Different techniques are present to determine the GP which include visual assessment, ultrasonic devices, radiographic technique, cone-beam computed tomography, periodontal probing, and transgingival probing.[1516] The transgingival probing is the steady way to determine the GP reported by Fu et al. 2010[17] and Greenberg et al. 1976,[18] and this is why transgingival probing is preferred over all other methods to assess the GP.

Wennström in 1996[19] reported that there is a paucity of data available which have studied the relationship between the thickness of gingiva and malocclusion with respect to the severity of crowding. In the present study, the mean GB of maxillary anterior tooth number 12 and 22 in severe crowding has the greater phenotype. Furthermore, for the mandibular anterior teeth, the GP of the 32 and 42 showed a greater phenotype in severe crowding.

The existing literature stated that there is a more lingual placement of mandibular central incisor tooth germ with respect to the mandibular lateral incisor, especially in the presence of crowding.[20] This will lead to more amount of alveolar bone, greater keratinized gingiva, and greater GP.[8] Our results are in accordance with the study done by Kaya et al. 2017[21] who reported that in Angle's Class III group, the gingival thickness of the mandibular right central and lateral incisor had thin phenotype.[16] As stated by Wennström 1996[19] when the buccolingual thickness of the gingiva decreases, then the apicocoronal height also decreases.

In the present study, when the GP was compared with Angle's malocclusion, there was no significant association found between them. Zawawi et al. 2012 found no relation between the thickness of the gingiva and the severity of crowding in the mandibular anterior,[4] but Materese et al. 2016[22] stated that on the basis of alignment of the tooth, the facial characteristics and the thickness of the gingiva are subject to change.

The other important parameter considered in our study was WAG. In maintaining the periodontal health, the importance of WAG has been studied in the adult population. The mucogingival junction is a crucial anatomical feature in determining the width of the gingiva that can be differentiated by various methods, so the exact position of this junction can be visualized following staining with the Lugol's iodine solution to determine the exact location endpoint of keratinization, as indicated by Fasske and Morgenroth.[23]

In the present study, the WAG shows a statistically significant result with respect to the 33 and 43 (P < 0.05) in severe crowding. It has likewise been determined that the tooth germ of the mandibular permanent canines was situated a similar way as the mandibular primary canine roots, in this manner, implying that the width of keratinized gingiva (WKG) and gingival thickness (GT) are not as much as that of the mandibular incisor teeth. Our finding was consistent with the study by Kaya et al. 2017[21] which stated that the mandibular canine WKG is less than the mandibular canine incisors.

Furthermore, Zawawi et al. 2012[4] investigated the relationship between GP and Angle's classification and reported no statistically significant relationship between them. In the present study also, there was no association between Angle's classification and GP in the maxillary and mandibular anterior regions.

As the severity of crowding increases, the GP and WAG in the mandibular and maxillary canines may expect to increase or decrease depending upon the position of teeth. This is mainly due to the reality that the eruption is more vestibular in position.[20]

Even so, teeth movement in this region should be done within the anatomical limits of the alveolar bone with controlled orthodontic forces. When the incisor protrusion is planned, it is important to consider the GP and WAG as a prime concern factor.

CONCLUSION

Within the limitation of the study, it can be concluded that the teeth in the maxillary and mandibular anterior esthetic teeth show the thin phenotype. With the increase in the severity of crowding, the GP and WAG vary depending on the position of the tooth. As the severity of crowding increases, the WAG of the canines and lateral incisors decreases. The gingival thickness decreases in the canine and lateral incisor with an increase in the severity of crowding, whereas no association was found between the Angle's classification and the mean GP of the maxillary and mandibular anterior region teeth.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.