Estimation of vestibular depth: An observational cross-sectional study

Abstract

Background:

The vestibular depth (VD) varies to a great extent among individuals and at different points of reference. The normal range of depth of the vestibule at different areas in the mouth remains to be established.

Aim:

The primary objective of this study is to assess the average VD around different teeth in the maxilla and the mandible. Furthermore, an attempt has been made to identify the various ranges of VD and understand what could be suggestive of a normal VD.

Materials and Methods:

The participants included were divided into four age groups, i.e., 6–14 years (Group 1), 15–30 years (Group 2), 31–50 years (Group 3), and >50 years (Group 4). Further, the subjects were grouped into subgroup A, periodontally healthy and subgroup B, gingival recession (GR). Group 1, 2, and 3 included 30 subjects each in subgroup A, while Group 4 subgroup B had 18 subjects. In case of subgroup B, Group 2 included 9 subjects, Group 3–31 subjects, and Group 4–30 subjects. Measurements included the depth of vestibule from 2 reference point, i.e., gingival margin (GM) and incisal edge (IE).

Results:

In subgroup A, the average VD from GM was found to be the least in the Group 1 i.e., 6–14 years (9.2 mm ± 4.26 in maxilla and 7.01 mm ± 3.14 in the mandible) and the highest in the Group 4 i.e., >50 years (12.06 mm ± 2.73 in maxilla and 10.08 mm ± 2.58 in the mandible). In the case of subgroup B, the least depth from GM was found in the Group 3 i.e., >30–50 years (9.44 mm ± 2.73 in the maxilla and 8.32 mm ± 1.7 in the mandible) and the maximum depth in the Group 4 (>50 years) (11.28 ± 2.31 in maxilla and 9.42 ± 2.87 in the mandible).

Conclusion:

The study provides a range of VD s in different areas of the mouth in periodontally healthy and individuals with GR, which will contribute to constitute a normal range of VD.

INTRODUCTION

The term “Vestibular Depth” has been used continuously and extensively in clinical practice since time immemorial and can be defined as “the distance between the crest of the lip and greatest concavity of the mucobuccal fold or the distance between the coronal border of the attached gingiva and the mucobuccal fold”.[1,2] The depth of vestibule and width of attached gingiva are crucial to be analyzed at an early stage, since an inadequate vestibular depth (VD) may lead to an unesthetic appearance, difficulty in performing plaque control measures and dentinal hypersentivity, etc.[3-8] VD has also been seen not only to be significantly influenced by the amount of gingival recession (GR) but vice versa, i.e., a shallow VD influences the outcome of root coverage therapy.[9-11] Some studies have concluded that the increased VD is associated with reduced plaque and bleeding indices.[12] In addition, decreased VD bears a poor prognosis of a fixed partial denture as it leads to marginal leakage and higher chances of GR, resulting in an unaesthetic appearance in the anterior region.[13,14]

The VD may vary to a great extent among individuals and at different points of reference. The depth of the vestibule is a key finding for all clinicians when examining a patient. However, the exact range of the VD among individuals still remains unconfirmed, as very limited data exists in this regard and barely any studies have been conducted till date to address this issue.[1,15] The studies which exist are either in edentulous patients[15] or only in relation to maxillary and mandibular anterior teeth.[1] The data obtained will contribute to define a reference range for clinicians. In case it is lesser than the normal range, the patient can be monitored over time and arrangements can be made in time to prevent the problems associated with a shallow vestibule.

The primary objective of this study is to assess the average VD around different teeth in the maxilla and mandible. Furthermore, an attempt has been made to identify the various ranges of VD and understand what could be suggestive of a normal VD.

MATERIALS AND METHODS

This is a cross-sectional observational study which was done in individuals who attended the outpatient department of a dental college with effective from February 2021 to February 2022. The study was approved by the human ethical board of our Institute and was conducted in accordance with the Declaration of Helsinki 1975, revised in 2013. The study was registered with Clinical Trials Registry of India. A pilot study of five subjects was performed preceding the main study for feasibility. The pilot data was not included in the main study.

The sample size was calculated using the nMaster 2.0, (Department of Biostatistics, CMC, Vellore, Tamil Nadu, India). The power of the study was taken to be 80% and Confidence Interval (C. I.) of 95% was taken. The sample size calculation was done as per the article by Chen et al.[15] The sample size was estimated to be a minimum of 50 per age group with equal division into the periodontally healthy and with GR.

The patients attending the outpatient department of a dental college, fulfilling the following inclusion and exclusion criteria and providing their informed consent were included in the study. The inclusion criteria were as follows: (a) age group 6 years to >50 years; (b) individuals who gave no history of any systemic disease which has direct influence on the gingival health; (c) periodontally healthy (i.e., <10% bleeding sites with probing depths (PDs) ≤3 mm and no evident sign of inflammation according to 2 0 1 7 World Workshop[16]; (d) generalized GR (>30% of the sites) with PD of ≤3 mm, <10% bleeding on probing and no evident sign of inflammation (According to 2017 world workshop)[16] (cases included were irrespective of etiology); and (e) patient should have minimum 20 teeth i.e., one incisor, one canine, 1^st premolar, 2^nd premolar, 1^st molar, and 2^nd molar in each arch. The exclusion criteria were (a) patients with malposed/carious/fractured teeth/attrition; (b) patients with prosthetic restoration and orthodontic treatment; and (c) individuals with history of smoking.

After segregating for the inclusion and exclusion criteria, the patients were divided into the following age groups: Group 1: 6–14 years, Group 2: 15–30 years, Group 3: 31–50 years, Group 4: >50 years. The patients included in each age group were divided into two subgroups-Periodontally healthy (subgroup A) and those with GR (subgroup B). Once the various groups and subgroups were selected, the teeth of the patients enrolled were examined. The teeth examined were in the combination of either 22, 24, 26, 41, 43, 45, and 47 or 11, 13, 15, 17, 32, 34, and 36. This meant that in every group if patient X had their 22, 24, 26, 41, 43, 45, and 47 teeth examined then the next patient, patient Y had 11, 13, 15, 17, 32, 34, and 36 examined. Again the next patient got 22, 24, 26, 41, 43, 45, and 47 teeth examined and so on. This way the VD across all the teeth in the dentition could be examined in every group. The division of teeth was for the convenience of the patients and limited the time required to examine each individual.

The VD was measured from 2 reference points: (1) from incisal edge (IE) and (2) from gingival margin (GM) in periodontally healthy cases and with recession.

The measuring instrument was UNC 15 having measuring capacity of 15 mm only. As the measurements of VD were anticipated to be more than 15 mm, it was decided to measure the depth in parts to arrive to the final value. The sections were divided on the basis of standard reference points. In periodontally healthy and with recession, the following measurements were taken to consolidate the VD [Figures 1 and 2].

Figure 1.

Measurements taken in Periodontally Healthy cases. Abbreviations-A- IE, B-GM, C-Deepest point of VES, VD. VES – Vestibule, VD – Vestibular depth, IE – Incisal Edge, GM – Gingival Margin

Figure 2.

Measurements taken in Gingival Recession cases (Abbreviations-A- IE, B-GM, C-Deepest point of VES, VD. VES – Vestibule, VD – Vestibular depth, IE – Incisal Edge, GM – Gingival Margin

1. IE to GM

2. GM to VD-this was done with the lip completely relaxed)[17]

3. Additional measurement of cementoenamel junction (CEJ) to GM was made in GR cases and added to the GM to VD value. This was done so that the VD in periodontally healthy can be compared to those with GR as GM is generally considered to be at CEJ. Individual measurements were not compared with each other as it was not the objective of the study.

   • Therefore VD = IE to VES (IE to GM) + (GM to VES) [Figure 1]

   • In case of GR, VD = (IE to GM) + (GM to VES) where IE to GM = (IE to CEJ) + (CEJ to GM) [Figure 2].

While taking the measurements in case of incisors the line correlating with the midpoint of the IE was considered. While measuring canines, canine buccal prominence tip/canine prominence if present or midpoint was taken into consideration. In case of premolars, the buccal prominence/buccal cusp tip and for 1^st and 2^nd molars mesiobuccal developmental groove were used.

After all the measurements were taken, the data was tabulated and subjected to statistical analysis.

Statistical analysis

Inferential statistical analysis has been carried out in the present study. Results on continuous measurements were presented on mean ± standard deviation (Min-Max). Significance was assessed at 5% level of significance. Independent ‘t’ test was used to compare the study parameters between two groups and analysis of variance for comparisons between more than two groups.

RESULTS

The total number of subjects included in the study were 178 out of which 55% (n = 98) were males and 44.9% (n = 80) were females. In subgroup A (periodontally healthy), there were 30 individuals in Group 1, 39 in Group 2, 30 in Group 3, and 18 in Group 4. In subgroup B (GR), there were 31 patients in Group 3 and 30 in Group 4. In Group 1, we didn’t find any patients (n = 0) and in Group 2 only 9 patients were found; therefore, Group 1 and Group 2 were not included for statistical analysis.

Table 1 analyzes the IE to the deepest point of vestibule (VES) at different teeth in maxilla and mandible in different age groups. The IE to VES values in Group 1 was 13.30 ± 2.21, Group 2 17.77 ± 1.53, Group 3 18.64 ± 1.89, and Group 4 19.96 ± 1.73. These measurements were from the IE to the deepest point of the vestibule, so the location of the GM (presence or absence of GR) did not affect the overall measurement. For this reason, the Tables 1 and 2 with IE to VES do not have the division of periodontally healthy and recession.

Table 1.

Age Group wise IE- VES in Maxilla and Mandible at different sites

Site	Mean±SD				ANOVA	P
	Group 1 (6-15 years)	Group 2 (>15-30 years)	Group 3 (>30-50 years)	Group 4 (>50 years)
Overall mean	13.30±2.21	17.77±1.53	18.64±1.89	19.96±1.73	86.363	<0.001 (S)
Range	9-21	11-26	11-29	11-27
Maxilla
Incisors	16.87±5.24	21.21±2.55	22.00±2.38	23.17±2.40	27.590	<0.001 (S)
Canine	16.13±4.88	21.11±2.45	21.63±2.91	22.75±2.21	15.415	<0.001 (S)
Premolar	16.50±2.76	18.36±2.33	19.52±2.62	20.60±2.54	17.422	<0.001 (S)
Molar	7.60±7.45	16.21±2.35	16.84±2.75	18.60±2.95	53.185	<0.001 (S)
Mandible
Incisors	14.17±2.09	16.74±2.30	17.82±2.22	19.31±2.33	34.168	<0.001 (S)
Canine	16.53±2.50	19.35±2.70	19.81±2.59	20.92±3.22	7.905	<0.001 (S)
Premolar	14.37±2.55	17.28±2.05	18.16±2.20	19.73±2.83	31.400	<0.001 (S)
Molar	7.30±6.66	14.41±2.49	15.43±2.75	16.50±2.75	44.163	<0.001 (S)

P of 0.05 or lower was considered statistically significant. All the measurements are in millimetres. ANOVA – Analysis of variance; SD - Standard deviation; S – Statistically significant; P – Probability value; IE – Incisal Edge; VES – Deepest point of Vestibule

Table 2.

Gender wise IE - VES in Maxilla and Mandible at different sites

Site	Maxilla				Mandible
	Mean±SD		Independent t	P	Mean±SD		Independent t	P
	Males	Females			Males	Females
Group 1 (6-15 years)
Overall mean	13.84±6.72	14.16±6.78			12.57±5.31	12.63±5.23
Incisors	16.79±5.47	16.94±5.22	0.078	0.939 (NS)	13.79±2.08	14.50±2.10	0.934	0.358 (NS)
Canine	15.00±6.71	17.13±2.59	0.832	0.421 (NS)	17.43±2.64	15.75±2.25	1.331	0.206 (NS)
Premolar	17.00±2.86	16.06±2.70	0.925	0.711 (NS)	14.14±2.35	14.56±2.78	0.443	0.661 (NS)
Molar	7.14±7.50	8.19±7.74	0.374	0.711 (NS)	7.36±6.82	7.25±6.73	0.043	0.966 (NS)
Group 2 (>15-30 years)
Overall mean	19.04±3.15	18.27±3.14			16.84±2.67	16.05±2.62
Incisors	21.72±2.82	20.76±2.26	1.180	0.245 (NS)	17.11±2.22	16.43±2.38	0.921	0.363 (NS)
Canine	21.75±2.66	20.64±2.29	0.978	0.342 (NS)	19.80±2.62	18.90±2.85	0.736	0.471 (NS)
Premolar	18.67±2.25	18.10±2.43	0.758	0.453 (NS)	17.50±2.15	17.10±2.00	0.609	0.546 (NS)
Molar	16.83±2.20	15.67±2.39	1.573	0.124 (NS)	14.56±2.50	14.29±2.53	0.334	0.741 (NS)
Group 3 (>30-50 years)
Overall mean	18.41±3.59	19.31±3.40			17.25±3.04	16.41±2.72
Incisors	22.06±2.84	22.00±1.83	0.104	0.918 (NS)	18.03±2.36	17.66±2.09	0.653	0.516 (NS)
Canine	21.79±3.24	21.50±2.68	0.264	0.794 (NS)	19.76±3.01	19.92±2.14	0.161	0.873 (NS)
Premolar	19.94±3.09	19.07±2.02	1.278	0.206 (NS)	18.71±2.38	17.66±1.88	1.896	0.063 (NS)
Molar	17.13±2.90	16.59±2.64	0.757	0.452 (NS)	16.58±2.84	14.28±2.14	3.535	0.001 (significant)
Group 4 (>50 years)
Overall mean	21.06±2.92	20.33±2.86			18.63±2.92	17.38±2.95
Incisors	23.26±2.54	22.71±2.13	0.706	0.483 (NS)	19.49±2.42	18.64±2.13	1.138	0.261 (NS)
Canine	23.06±2.14	22.00±2.38	1.069	0.296 (NS)	21.00±3.65	20.43±1.51	0.397	0.695 (NS)
Premolar	20.71±2.65	20.29±2.20	0.535	0.595 (NS)	20.03±2.57	18.71±3.38	1.474	0.147 (NS)
Molar	18.77±3.10	17.93±2.62	0.897	0.374 (NS)	16.77±2.92	15.57±2.21	1.383	0.173 (NS)

P of 0.05 or lower was considered statistically significant. All the measurements are in millimetres. S – Statistically S; SD – Standard deviation; NS – Not significant; P – Probability value; IE – Incisal Edge; VES – Deepest point of Vestibule

Table 2 evaluates the IE to VES at different sites gender wise. The values in males in Group 1 were- maxilla: 13.84 ± 6.72, mandible: 12.57 ± 5.31, in Group 2 -maxilla: 19.04 ± 3.15, mandible: 16.84 ± 2.67), in Group 3- maxilla: 18.8 ± 3.59, mandible: 17.25 ± 3.04 and in Group 4 -maxilla: 21.06 ± 2.92, mandible: 18.63 ± 2.92. The values in females in the different groups were as follows: Group 1 (maxilla: 14.16 ± 6.78, mandible: 12.63 ± 5.23), Group 2 (maxilla: 18.27 ± 3.14, mandible: 16.05 ± 2.62), Group 3 (maxilla: 19.31 ± 3.40, mandible: 16.41 ± 2.72) and Group 4 (maxilla: 20.33 ± 2.86, mandible: 17.38 ± 2.95). It has been observed that there was not much difference between the values in males and females for different teeth in maxilla and mandible across all age groups. The different values in individual teeth groups across maxilla and mandible in males and females are shown in Table 2.

Table 3 shows The GM to VES values in Group 1 and 2. In Group 1, the overall mean was maxilla: 9.2 ± 4.26; mandible: 7.01 ± 3.14 and in Group 2, maxilla: -10.64 ± 2.23; mandible: 8.49 ± 1.75. The values across different teeth in maxilla and mandible in males and females have been mentioned in Table 3.

Table 3.

GM – VES for 6-15 years and >15-30 years in Maxilla and Mandible at different Sites

	6-15 years								>15-30 years
Overall Range	4-15								4-17
	Maxilla				Mandible		t test	P	Maxilla				Mandible		t test	P
Overall Mean±SD	9.2±4.26				7.01±3.14		4.17	4.50 (NS)	10.64±2.23				8.49±1.75		7.77	3.57(NS)
Range	5-15				4-12				6-17				4-13
	Mean±SD				Mean±SD		t test	P	Mean±SD				Mean±SD		t test	P
Incisor	10.3±3.25				7.13±1.72		4.77	1.3 (NS)	12.13±1.94				8.2±1.65		8.45	1.06(NS)
Canine	11.2±1.57				8.8±1.74		3.85	0.00 (S)	11±1.65				9±1.46		3.51	0.001(S)
Premolar	10.45±2.40				8.2±1.92		4.033	0.00 (S)	10.27±2.23				8.97±1.54		2.63	0.01 (S)
Molar	4.8±4.76				3.93±3.79		0.78	0.44(NS)	9.37±1.90				8.07±2.07		2.53	0.013(S)
	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	ttest	P	Male Mean±SD	Female Mean±SD	ttest	P	Male Mean±SD	Female Mean±SD	t test	P
Incisor	10.57±3.39	10.1±3.22	0.370	0.715 (NS)	6.5±1.09	7.6±2.03	1.734	0.094 (NS)	11.93±2.20	12.31±1.74	0.533	0.598 (NS)	8.21±1.63	8.19±1.72	0.044	0.966 (NS)
Canine	11.42±1.38	11.00±1.85	0.836	0.418 (NS)	9.1±1.77	8.5±1.77	0.701	0.496 (NS)	10.43±1.81	11.50±1.41	1.286	0.221 (NS)	9.43±1.51	8.63±1.41	1.066	0.306 (NS)
Premolar	10.92±2.40	10.1±2.42	0.911	0.370 (NS)	8.14±1.70	8.31±2.15	0.237	0.814 (NS)	9.50±1.87	10.94±2.35	1.834	0.077 (NS)	8.93±1.14	9.00±1.86	0.124	0.902 (NS)
Molar	4.5±4.83	5.0±4.84	0.242	0.811 (NS)	3.86±3.76	4.0±3.95	0.101	0.920 (NS)	9.57±1.56	9.19±2.20	0.545	0.590 (NS)	7.93±2.17	8.19±2.04	0.337	0.739 (NS)

GM- Gingival Margin, VES- Deepest point of vestibule, P value of 0.05 or lower was considered statistically significant, NS- not significant, S- significant, SD – Standard Deviation. All the measurements are in millimeters; t – Independent t test; P – Probability value

The GM-VES for Group 3 in healthy and GR are shown in Table 4. The mean values in healthy were maxilla: 10.78 ± 2.64, mandible: 8.55 ± 2.07 and in case of GR were maxilla: 9.44 ± 2.73, mandible: 8.32 ± 1.7. Further the mean values across different teeth in different genders have been analyzed in the table.

Table 4.

GM – VES for >30-50 years in Maxilla and Mandible at different Sites

		>30-50 Years
Periodontally Healthy								Recession
Overall Range	5-19								3-15
	Maxilla				Mandible		t test	P	Maxilla				Mandible		t test	P
Overall Mean±SD	10.78±2.64				8.55±2.07		6.8	1.11 (NS)	9.44±2.73				8.32±1.7		3.56	0.00 (S)
Range	6-19				5-15				3-15				4-12
	Mean±SD				Mean±SD		t test		Mean±SD				Mean±SD		t test	P
Incisor	11.9±2.17				8.57±1.87		6.37	3.29 (NS)	11.57±1.33				8.24±1.45		9.23	5.57 (NS)
Canine	11.47±2.26				9.27±2.28		2.65	0.01(S)	11±2.36				9.13±2.06		2.30	0.03(S)
Premolar	11±2.6				8.97±1.73		3.56	0.00(S)	7.33±2.88				8.8±1.13		-2.6	0.01(S)
Molar	9.1±2.56				7.77±2.31		2.11	0.04(S)	8.63±1.65				7.5±1.89		2.47	0.02(S)
	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P
Incisor	11.08±2.60	12.53±1.58	-1.63	0.11 (NS)	8.77±2.05	8.41±1.77	0.51	0.61 (NS)	11.76±1.21	11.25±1.48	1.07	0.29 (NS)	8.11±1.60	8.5±1.17	-0.72	0.48 (NS)
Canine	9.60±1.14	12.4±2.12	-2.73	0.02 (S)	8.75±2.71	9.86±1.68	-0.93	0.37 (NS)	10.89±2.84	11.17±1.60	-0.21	0.83 (NS)	8.78±1.79	9.67±2.50	-0.81	0.43 (NS)
Premolar	10.69±3.35	11.23±1.92	-0.56	0.58 (NS)	9.31±2.02	8.70±1.49	0.94	0.35 (NS)	7.78±2.39	6.67±3.5	1.04	0.31 (NS)	8.67±1.28	9±0.82	-0.56	0.58 (NS)
Molar	9.31±3.30	8.94±1.92	0.38	0.70 (NS)	8.62±2.99	7.12±1.41	1.82	0.08 (NS)	8.78±1.83	8.42±1.38	0.58	0.57 (NS)	7.83±1.89	7±1.86	1.19	0.24 (NS)

GM- Gingival Margin, VES- Deepest point of vestibule, P value of 0.05 or lower was considered statistically significant, NS- not significant, S- significant, SD – Standard Deviation. All the measurements are in millimeters; t – Independent t test; P – Probability value

Table 5 shows the GM-VES in Group 4 individuals in periodontally healthy and with GR. The mean values in healthy were (maxilla: 12.06 ± 2.73, mandible: 10.08 ± 2.58) and in GR (maxilla: 11.28 ± 2.31, mandible: 9.42 ± 2.87). The gender wise (male/females) in different teeth in maxilla and mandible are discussed in Table 5.

Table 5.

GM – VES for >50 years in Maxilla and Mandible at different Sites

>50 Years
	Periodontally Healthy								Recession
Overall Range	5-18								2-18
	Maxilla				Mandible		t test	P	Maxilla				Mandible		t test	P
Overall Mean±SD	12.06±2.73				10.08±2.58		4.31	3.11 (NS)	11.28±2.31				9.42±2.87		5.34	2.39 (NS)
Range	6-17				5-18				6-18				2-16
	Mean±SD				Mean±SD		t test	P	Mean±SD				Mean±SD		t test	P
Incisor	13.10±2.66				10.37±2.38		3.33	0.001 (S)	12.7±1.93				9.47±2.44		5.68	4.54 (NS)
Canine	12.44±2.55				10.3±2.63		1.8	0.09 (NS)	11.93±1.98				9±3.42		2.87	0.01 (S)
Premolar	12.53±2.17				10.74±2.76		2.22	0.03 (S)	11.2±2.45				10.4±2.57		1.23	0.22 (NS)
Molar	10.37±2.77				9±2.40		1.62	0.11 (NS)	9.63±1.56				8.6±2.59		1.87	0.07 (NS)
	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P	Male Mean±SD	Female Mean±SD	t test	P
Incisor	13.09±2.84	13.12±2.59	-0.03	0.98 (NS)	10.91±2.51	9.62±2.13	1.17	0.26 (NS)	12.62±2.10	13±1.09	-0.41	0.68 (NS)	9.25±2.54	10.33±1.97	-0.97	0.34 (NS)
Canine	13.33±2.66	10.67±1.15	1.62	0.15 (NS)	10.2±3.03	10.4±2.51	-0.11	0.91 (NS)	11.45±2.11	13.25±0.5	-1.64	0.12 (NS)	8.77±3.58	10.5±2.12	-0.65	0.52 (NS)
Premolar	12.27±1.90	12.87±2.59	-0.59	0.56 (NS)	10.73±2.57	10.75±3.19	-0.02	0.99 (NS)	11.25±2.67	11±1.41	0.22	0.83 (NS)	10.46±2.62	10.17±2.56	0.24	0.80 (NS)
Molar	10.82±3.09	9.75±2.31	0.82	0.42 (NS)	9.64±2.38	8.12±2.3	1.39	0.18 (NS)	9.58±1.72	9.83±0.75	-0.34	0.73 (NS)	8.58±2.73	8.67±2.16	-0.07	0.94 (NS)

GM- Gingival Margin, VES- Deepest point of vestibule, P value of 0.05 or lower was considered statistically significant, NS- not significant, S- significant, SD – Standard Deviation. All the measurements are in millimeters; t – Independent t test; P – Probability value

The patients included in the recession groups were that of Generalized recession, i.e., >30% of the sites in the full mouth had GR. This was irrespective of the amount or the type of GR present. In addition, it is also to be noted that not all the sites where the VD s were measured had GR. The mean recession in Group 3 was 1.3 mm and in Group 4 was 1.6 mm.

DISCUSSION

It is a widely accepted fact that the VD[2] is an important entity for clinicians, be it in terms of placement of dentures or maintaining general health. A shallow vestibule is bound to ultimately lead to poor oral hygiene due to difficulty in performing adequate plaque control,[3,4,8,12] stabilization of dentures[13,14] or unaesthetic appearance.[3,4] Aberrant frenal and muscle attachments with a shallow vestibule results in the pull syndrome of the marginal gingiva and aggravates the accumulation of plaque in the gingival sulcus.[5-8,18] This may result in gingival inflammation in those with poor oral hygiene. Additionally, the effect of poor oral hygiene is gingivitis which further results in GR.[19] This study measures the range of VD in the area of various teeth in different age groups and genders.

The individuals included in the present study were numbered from 1 to 30 per age group. They were further divided into 2 groups depending on which combination of teeth were examined in their mouth for measuring the VD against specific teeth. The group of teeth were either 22, 24, 26, 41, 43, 45, 47 or 11, 13, 15, 17, 32, 34, and 36. In this way, the VD across all the teeth in the dentition were examined.

The age groups included in the study were Group 1 6–15 years, Group 2 >15–30 years, Group 3 >30-50 years, and Group 4 >50 years. The division in age groups was an important aspect of the study. The first age group (6–15 years) was of the subjects who are were in the stage of growth and mixed dentition period till all the permanent teeth have erupted and facial growth has completed. The maximum growth of maxilla and mandible happens after the age of 12 years and continues actively till 14 years; hence, the depth of vestibule alters drastically as the individual completes 14 years and then stabilizes from 15 years to >50 years.[20] In addition, all the permanent teeth except 2^nd and 3^rd molars have erupted by the age of 14 and the mixed dentition period is complete.[20]

The age groups 6–15 years and >15–30 years were included in the study on the basis that the amount of clinical attachment loss (CAL) and GR was the lowest at the age of 30 years,[21] suggesting very low levels of periodontitis till this age.

The division in age groups >30–50 years and >50 years was made as it has been observed that the prevalence of periodontitis increases with age, reaching a maximum by 38 years with the highest in the third and fourth decade of life.[22] It has also been identified that the amount of periodontal destruction stabilizes after 50 years.[22] In addition, it has been stated that the rate of periodontal breakdown was higher in 32–38 years age group compared to 26–32 years.[23] It was observed in a NHANES and SHIP trend study, that increased PD is the main reason for CAL in individuals’ up to 44 years but in older individuals the CAL was mostly due to GR and not PD.[21]

The VD measurements were done from two anatomical land marks: IE and GM to the deepest part of vestibule. In the measurements of VD from GM, the participants in each age group were also divided into periodontally healthy[16] and with GR. The aim of this division was to measure the VD in periodontally healthy and in cases of GR and to observe if any difference existed between these two groups. As mentioned earlier, as the prevalence of periodontal disease is very less in younger age groups[24], hence we were unable to find any patients of GR in Group 1 (6–15 years) and very few in Group 2 (>15-30 years). Furthermore, the measurements were analyzed on the basis of gender and teeth type in all the age groups.

For the VD measurements from IE, GM position was of no significance, so that group was not divided in periodontally healthy and with recession.

The VD increased with age across all age groups. The VD was observed to have an increasing trend across all age groups in all the teeth types analyzed. The amount of increase in VD was substantial and significant when the change was observed between Group 1 and other groups. This could be attributed to the fact that Group 1 was 6–15 years and a growth period of face and skull. The measurements were less in this age group compared to Group 2, 3, and 4. The difference between Group 2, 3, and 4 is not much as growth stabilizes by 15 years. The depth of the vestibule is dependent on various factors like, attachment of muscles, height of lip, height of alveolar bone, etc.[25] It was also observed that the VD was more in maxilla in comparison to the mandible. It could be attributed to the fact that the maxilla is nonmobile and the depth of vestibule in the maxilla is affected by greater amount of keratinized ginvgiva present in the maxilla and an increased height of upper lip.[25]

The mandible, on the other hand, is bounded by certain muscles like mentalis and buccinator muscles whose contraction causes the VD to become shallow and pushes the lower lip in the upward direction.[26]

On intragroup examination, it was observed that VD from IE and GM was similar in incisor, canines and premolar regions. On intergroup comparison, it was observed that the VD in Group 1 in these three teeth was much less as observed in Groups 2, 3, and 4. The difference in VD in these three teeth in Groups 2, 3, and 4 was in similar range and not much change was observed across age groups.

The measurement of VD from IE and GM in periodontally healthy was found to be more in maxilla than mandible across all age groups. Furthermore, on the evaluation of gender wise data, it was observed that VD from IE and GM was more in females in group 1 (6–15 age group) across maxilla and mandible and all teeth types but in other age groups the VD was more in males across maxilla and mandible and across all teeth types. The observation of more VD in females in Group I (6–15 years) could be credited to the fact that the growth spurts in females occur at the age of 10 years which is 2 years earlier than it occurs in boys. The growth spurts are complete by the age of 16 years. The higher value of VD in males could be due to the fact that males have a larger facial bone height,[27] width of attached gingiva,[28] greater upper lip length,[29,30] and larger tooth size[31] in comparison to females and hence have a higher value of VD.

On intragroup comparison in Group 1, the VD was very less in the molar region of maxilla and mandible compared to the other teeth. The reason for this could be that the eruption of all the teeth and the growth of the area around them is complete by the age of 14 years except the regions of 2^nd and 3^rd molars, which are not achieved before the age of 14 years.[32] Although we do not have literature with regard to the VD in the molar region, it is stated that the growth of the maxilla and mandible in the molar region and the development of the muscular attachments is not completely achieved by the age of 14 years.[32]

Further, as we move to >15–30 years, the VD at the molar region of maxilla and mandible was significantly increased as compared to Group 1. This was observed because the growth of the maxilla and the mandible and its muscular attachments was complete and stabilized by the time the individual reached 15–30 years.[32] After this, the change in the VD at the molar region in the maxilla and mandible in ages >30–50 years and >50 years was almost the same as that of >15–30 year individuals. This could be because the growth of the maxilla and the mandible and its attachments are stabilized by the time the individual reaches >30–50 years and >50 years.[20]

Another trend which was observed and common across all age groups was the amount of VD was least in molar regions in comparison to the other teeth, i.e., incisors, canines, and premolars in both maxilla and mandible and both the genders. The reason for this could be the anatomy of the external oblique ridge, in case of the mandible, which runs from the 2^nd premolar (mental foramen) to the 2^nd molar and then becomes continuous with the anterior border of the ramus. This area is also the attachment of the buccinator muscle which is restricting in nature[33] and hence would shorten the VD. The same muscle is present in the maxilla in the region of the maxillary molars and functions to compress the cheek against the molar teeth.[33] In addition, the reduced VD in the molars could also be associated with the buccal frenum being a highly activated broad area extending from the premolar to the molar region. A wide majority of individuals had more than 1 buccal frenum (>60%) in the maxillary region and 13% had fan shaped connections.[34] The wide extension of the buccal frenum causes the vestibule to become shallow.

We measured and observed the VD in cases of GR without classifying it on the basis of type and depth. In the pool of cases with GR included in our study, it represents a picture of the average recession found in the general population. The average GR observed in our cases for the age groups >30–50 years and >50 years was similar to the NHANES study.[21] The depth of vestibule is affected by the amount the GM moves apical to the CEJ on the buccal aspect. We measured the depth of the vestibule from GM in GR cases. Since all our measurements have been taken from the mid buccal area of all the teeth, the type of recession which is based on the interdental loss of the gingiva was not required to be recorded. In all the various types of classifications of recession, the midfacial recession is mandatory to be recorded first and the same was done in our study. The values of VES to GM in recession for Group 3 and 4 were lower than the values in periodontally healthy in the same age groups. It could be observed that the VD was comparable with the amount of GR in both the age groups. It is important to be noted that the individuals included had generalized GR, i.e., GR present in >30% of the sites, implying that not all the sites where VD was measured had GR present in them. Finally, it could be inferred as the more the amount of GR present, the lesser the VD.

Studies with a larger sample size, incorporation of other ethnic populations, inclusion of other measurement methods like digital linear and volumetric measurements would be beneficial to provide a better understanding of the vestibular depth. Additionally, the etiology and quantification of recession to measure VD, VD in systemic diseases and among smokers and to objectively define and quantify what constitutes a “shallow vestibule” would give more clarity to this topic in the future.

CONCLUSION

The current study puts forth a range of VD across various age groups, teeth and genders in different areas in periodontally health and GR. The VD was seen to be decreased in case of GR compared to periodontally healthy cases. In addition, if one knows what the average depth is in a healthy state then identifying the problems associated with a shallow depth and making an attempt to prevent what may happen in the future becomes feasible. However, to have a clear cut definition of a “shallow vestibule” still remains to be addressed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.