A study to evaluate the prevalence of teeth without clinically detectable mucogingival junction

Abstract

Context:

The mucogingival junction (MGJ) is one of the important anatomical entities which mark the apical termination of attached gingiva, except that at palatal side. Its position is genetically determined like other organs and tissues in our body. There are certain anatomic aberrations such as abnormal teeth eruption or high frenal attachments and pathologies, such as periodontitis, leading to its absence. There are no studies on the prevalence of teeth having no clinically detectable MGJ. There is a resurgence of importance of attached gingiva, reflected by the definite presence of MGJ, through the field of dental implantology.

Aims:

We aim to evaluate the prevalence of teeth without clinically detectable MGJ on the buccal aspect of dentate alveolar processes.

Settings and Design:

This cross-sectional observational clinical study was conducted in the department of periodontology which was approved by the institutional ethical committee.

Materials and Methods:

Periodontally healthy as well as diseased patients of age 18–50 years were included in the study. The detection of MGJ was carried out by visual method, tension test, rolling probe method, and Lugol's iodine solution, and confirmation from any two methods was considered for the absence of MGJ. The etiology of MGJ absence (gingival recession, pocket till MGJ, trauma, abnormal frenal attachment, malposition of tooth, abnormal habits, severe abrasion, etc.,) was also evaluated.

Statistical Analysis Used:

Simple statistics in the form of averages and percentages were used for calculations.

Results:

A total of 130 subjects (3637 teeth) were examined out of which 32 (24.6%) subjects showed no clinically detectable MGJ. In all subjects, on an average, every subject has 28 teeth and out of the total 3637 teeth analyzed, only 91 (2.5%) teeth were without detectable MGJ.

Conclusion:

Almost 25% of the population may show a tooth or few teeth without a clinically detectable MGJ. The prevalence of teeth without clinically detectable MGJ per mouth is very low at 0.7 (approximately 1 tooth/subject).

INTRODUCTION

The attached gingiva appears to be first described formally by Orban in 1948 as that part of the gingiva firmly attached to the underlying tooth and bone and stippled on the surface.[1] It plays an influential role in maintaining healthy and intact periodontium.[2] According to the Glossary of Periodontal Terms, the attached gingiva is firm, resilient, and tightly bound to the underlying periosteum and alveolar bone.[3] Facial aspects of the attached gingiva extend to loose and movable alveolar mucosa and demarcated by a mucogingival junction (MGJ). On the lingual aspect, it terminates at the junction of lingual alveolar mucosa, which is continuous with the mucous membrane lining of the floor of the mouth. The palatal surface of the gingiva in the maxilla blends imperceptibly with the firm and resilient palatal mucosa.

The attached gingiva is a part of keratinized gingiva, which aids in periodontium to increase resistance to external injury and contribute to stabilizing gingival margin against frictional forces and aids in dissipating physiological forces exerted by the muscular fibers of the alveolar mucosa on the gingival tissues. The presence of an “adequate” zone of gingiva is considered critical for the maintenance of marginal tissue health and for the prevention of continuous loss of connective tissue attachment.[4,5] One of the requirements of a comprehensive periodontal examination is evaluating the width of the attached gingiva. The MGJ serves as an important clinical landmark to assess the width of the attached gingiva.

A MGJ is an anatomical feature on intraoral mucosa, both on the buccal and oral aspects except palatal mucosa. It is defined as the point where the attached gingiva meets alveolar mucosa. The MGJ is clinically identified by visual method (VM), tension test (TT), rolling probe (RP) method, and histochemical staining by Lugol's iodine (LI) solution.[6,7,8] The MGJ forms the borderline between the genetically determined basal bone of the jaws and the alveolar processes, the growth of which is induced by the developing teeth.[7] Since MGJ remains stationary throughout adult life, changes in the width of the attached gingiva are caused by modifications in the position of its coronal portion.[9]

When there is an increase in the retraction of the gingival margin, caused either by chronic periodontal disease or by trauma from toothbrushing, the less is the width of the band of attached gingiva measured.[9] Hence, in the absence of the attached gingiva, the alveolar mucosa will form mucosal or marginal tissue without a definite MGJ.[10,11]

It is well known that reduced periodontium secondary to periodontitis and advanced recession because of periodontitis leads to loss of tissue up to and beyond MGJ. The presence of pockets because of periodontitis may also reach beyond MGJ.[12] These conditions make MGJ clinically nondetectable. Recently in 2021, Tarnow et al.[13] suggested new definitions for attached gingiva considering locations of MGJ, alveolar crest, and base of the intrabony defect around healthy and diseased teeth and implants. The MGJ can be present coronal or apical to the alveolar crest. A similar positioning of the MGJ can be present when there is an intrabony defect and the base of the pocket is apical to the alveolar crest. Based on these factors, they defined attached gingiva for different situations. The absence of attached gingiva is akin to the absence of MGJ but not for all situations.

Some nonpathological conditions like the vestibular eruption of teeth and buccal positioning of teeth may have alveolar mucosa as marginal tissue without detectable MGJ.[14] Traumatic injuries such as repetitive toothbrush injuries may lead to marginal tissue recession beyond MGJ, making it undetectable.[14] The agenesis of MGJ is not known yet. Developmental aberrations or genetic nonformation are yet to be evaluated for the absence of MGJ.

As of now, there are no reported studies determining the prevalence of absence of MGJ around the buccal aspects of teeth irrespective of their health status. The present study aims to evaluate the prevalence of subjects/teeth without clinically detectable MGJ on the buccal aspect. We also aim to identify the reason for the absence of MGJ (gingival recession, pocket till MGJ, abnormal habits, malposition of the tooth, trauma, severe abrasion, abnormal frenal attachment, etc.).

MATERIALS AND METHODS

The study population (n = 130) consisted of subjects visiting the outpatient department of periodontology in a dental college. Periodontally healthy as well as diseased patients giving written consent were considered. Patients referred for crown-lengthening procedures and implant-related treatments were relatively healthy. Patients reporting with uncontrolled systemic diseases such as uncontrolled diabetes, recently diagnosed thyroid problems, and physically and mentally handicapped patients were excluded. The study protocol was approved by the local institutional research committee. A dedicated pro forma was designed to evaluate the presence or absence of MGJ, etiological factors for an absence of MGJ, and other case history-related data.

This is a cross-sectional clinical observational study to evaluate the prevalence of absence of MGJ on the buccal side of teeth. The sample size was calculated to be at least 114.[15] Which means, a minimum of 114 subjects should be evaluated with a confidence level of 95% that the real value falls within ±5% of the measurement/observation considering an estimated population proportion of 8% in the overall population.

Inclusion criteria

1. Subjects with permanent dentition and at least 26 teeth present were considered

2. Both genders were considered for inclusion

3. The age range considered was 18 years–50 years

4. Third molars were excluded for examination and analysis

5. Patients with mental and physical disabilities and uncontrolled systemic diseases were excluded.

To determine the presence or absence of MGJ, all patients were clinically examined on dental chairs with proper lighting and appropriate armamentarium. Four methods to assess the MGJ were used. Out of these methods, if any of the two methods do not detect MGJ, then it was considered as absent and clinically nondetectable. If there was any doubt regarding the delineation of MGJ for one examiner, then the same was confirmed and correlated from another investigator. The methods are described as follows:

1. VM: VM assessment is based on the color difference between the gingiva and alveolar mucosa.[1] The mucosa beyond the MGJ is darker red than that of the attached gingiva which demarcated the MGJ [Figure 1]

2. TT: This is done by stretching the lip or cheek in outward, downward/upward, and lateral directions. The gingival margin is then observed for any movement of the free gingiva.[6] Any observable movement of the free gingival margin during stretching lips/cheeks is considered as positive with inadequate attached gingiva and absence of MGJ [Figure 2]

3. RP method: It is done by pushing the adjacent alveolar mucosa coronally with a blunt end of the probe, functional method as indicated by the border between movable mucosa and immovable gingiva.[7] If the tissues moved with the instrument without a definite tissue stop coronally, then the width of the gingiva was considered inadequate with the absence of MGJ. The fold formation of loose movable tissue during coronal movement with a definite coronal stop indicates the presence of MGJ, the fold cannot be relocated further coronally [Figure 3]

4. Using LI solution: The staining of the mucogingival complex with LI solution is based on the difference in the glycogen content.[16] The attached gingiva is keratinized with no glycogen in the most superficial layer and gives an iodo-negative reaction. Thus, LI solution stains only the alveolar mucosa and clearly demarcates the MGJ. If the whole of the marginal tissue gets stained, it is considered as the absence of MGJ. The solution is thoroughly applied with cotton pellet on the patient's gingiva and alveolar mucosa till a sharp demarcation between keratinized tissue and alveolar mucosa is observed [Figures 4 and 5].

Figure 1.

Visual examination of gingiva. A line demarcating attached gingiva and alveolar mucosa due to color difference. The alveolar mucosa is red, smooth, shiny rather than pink, and stippled compared to the attached gingiva

Figure 2.

Tension test. After stretching the cheek in the outward direction, the gingiva is retracted away from tooth surface or movement observed at the gingival margin

Figure 3.

Rolling probe test. The blunt end of probe rolled coronally, the mucosal or marginal curls around the cervical portion of tooth resembling minimal or no attached gingiva

Figure 4.

Lugol's iodine staining. After applying the solution, the alveolar mucosa turns brownish which demarcates mucogingival junction

Figure 5.

Staining with Lugol's iodine after rolling probe and tension tests ruled out the presence of mucogingival junction. Even though similar staining as of adjacent attached gingiva can be observed, the presence of pocket and marginal deflection ruled out mucogingival junction attachment

For sake of brevity, the following definitions were followed to identify the reasons behind the absent MGJ. The etiological factors assessed were as follows:

1. Gingival recession: It is the exposure of root surface by an apical shift in the position of the gingival margin.[17] The linear loss of soft tissue because of earlier periodontal disease or ongoing periodontal disease involving MGJ or beyond is considered in this category. The diagnosis of periodontitis for the involved tooth/teeth was an important criterion. Surgically treated periodontitis patients were also included in this category

2. Pocket till MGJ: The periodontal pocket is defined as pathologically deepened gingival sulcus. When the destruction continues unabated apically and reaches the junction of the attached gingiva and alveolar mucosa, the pocket thus formed would violate MGJ with no band of attached gingiva.[18] This condition may indicate periodontitis, endo-perio problems, or a draining periodontal abscess

3. Abnormal habits: Chronic habits such as fingernail biting, digit sucking, or sucking on objects such as pens, pencils, toothpicks, dental floss, or pacifiers are considered abnormal. In the absence of periodontitis-related recession, these abnormal habits may lead to loss of tissues beyond MGJ[19]

4. Malpositioned tooth: At times, tooth erupts through buccal alveolar mucosa, like the buccally erupted maxillary canines. They may not show the presence of MGJ. The position of teeth in the arch, the root-bone angle, abnormal eruption pathways, and the mesiodistal curvature of the tooth surface influence susceptibility to recession. On rotated, tilted, or facially displaced teeth, the bony plate is thinned. The pressure from mastication or toothbrushing damages the unsupported gingiva. The deleterious effects of the angle of the root in the bone are often observed in the maxillary molar area[20,21]

5. Trauma: Accidental trauma or iatrogenic traumas tearing away marginal tissues beyond MGJ were put in this category.[22] Trauma requiring surgical intervention with loss of MGJ was also categorized here

6. Severe abrasion: Tooth wear describes the loss of dental hard tissues from the surface of teeth. Abrasion is defined as the pathological wear of dental hard tissues via mechanical processes involving foreign objects. Both patient and material-related factors influence this condition. The brushing technique, brushing frequency, the force applied, type of bristle material, toothbrush stiffness, the abrasiveness, and pH of dentifrice cause gingival recession and expose root and predispose to cervical notching. Standard oral hygiene procedures, including tooth brushing and flossing, frequently lead to transient and minimal gingival injury. Although toothbrushing is important for gingival health, faulty technique, or brushing with hard bristles, can cause significant injury.[23] This injury can manifest as lacerations, abrasions, keratosis, or recession, with the facial marginal gingiva being affected most often. Loss of tissues beyond MGJ because of cumulative faulty oral hygiene habits was put in this category, which cannot be definitely categorized as periodontitis patients

7. Abnormal frenal attachments: Frenal attachments are thin folds of mucous membrane with or without enclosed muscle fibers that attach the lips to the alveolar mucosa and underlying periosteum.[24] A frenum can become a significant problem if tension from the lip movement pulls the mucosal margin away from the tooth. Similarly, aberrant muscle attachments may lead to tension and movable marginal tissues when stretching actions are undertaken. These conditions are clubbed in this category, as the movement of marginal tissues indicates the absence of MGJ

8. Any other: The crown-lengthening procedures, if improperly performed, may also lead to the absence of MGJ. The developmental or genetic absence of MGJ (absence of MGJ unrelated to any known cause on a healthy fully erupted tooth), absence of MGJ postorthodontics, and direct loss of periodontal tissues because of adverse habits such as tobacco quid, tobacco lime, gutkha, kharra, smoking, and chemical burn were categorized here.[25,26]

The data from each patient were collected, collated, and tabulated properly. The data were then subjected to simple mathematical tests, including averages and percentages. It is a prevalence study to identify relative percentages of teeth without a clinically detectable MGJ and teeth with MGJ acting as controls; there is no specific requirement for complex statistical methods.

RESULTS

The study was conducted in January 2020 in the outpatient department of periodontology. A total of 215 patients were checked for probable inclusion in this study; out of that 18 patients were not willing to participate in the study and 67 patients were excluded considering the inclusion criteria. A total of 130 subjects were finally included [Supplementary File 1] in this cross-sectional observational study to determine the prevalence of teeth without clinically detectable MGJ. This sample comprised BDS and MDS students as well who consented to the proposal. We used four methods to determine MGJ for each tooth, and we considered that at least 2 of 4 tests should be negative for confirmed MGJ absence. A total of 32 (24.6%) subjects did not show the presence of MGJ at least with one or more teeth. In all subjects, a total of 3637 teeth were evaluated for the MGJ. Considering all the patients, only 3 teeth were absent in included patients, one with 2 molars and another patient with a single molar absent. The average teeth per patient turned out to be 27.9, almost a complete set of teeth. There was no detectable MGJ on 91 (2.5%) teeth. Females presented with a significantly higher number of absences of MGJ (65.6%) than males (34.4%) [Table 1]. Comparing etiological factors responsible for the detection of the MGJ, marginal tissue recession associated with periodontitis turned out to be the predominant factor (n = 48, 52.7%) [Table 2] and [Graph 1]. The mandibular left central incisor was found to be the most involved tooth type (26.37%) with no clinically detectable MGJ; it was closely followed by the mandibular right central incisor (24.17%) [Table 2]. Individual tooth numbers with ≥2 teeth without detectable MGJ were mentioned individually, and the other teeth include one tooth each (11, 12, 14, 16, 17, 21, 22, 36, and 44) having the absence of MGJ [Table 2]. Almost 76% of teeth with the absence of MGJ were related to periodontitis causes (recession and pockets till MGJ). The predominant reason for MGJ absence on incisors and canines was related to gingival recession, 54.7% and 58.3%, respectively. In turn, these were the only teeth (incisors 85.4% and canines 14.6%) showing gingival recession as etiology [Table 3]. The complete data for the distribution of teeth depending on etiology are presented in [Table 3].

Table 1.

Assessment of clinical detection of mucogingival junction

Identification of MGJ	Numbers of patients and teeth analysed		Gender
	Number of patients (n=130), n (%)	Number of teeth examined (n=3637), n (%)	Males, n (%)	Females, n (%)
MGJ detected	98 (75.4)	3546 (97.5)	43 (43.9)	55 (56.1)
MGJ not detected	32 (24.6)	91 (2.5)	11 (34.4)	21 (65.6)

MGJ – Mucogingival junction; n – number of

Table 2.

The etiology and tooth type for absence of mucogingival junction

Etiology	Teeth without clinically detectable MGJ, n (%)	Tooth type assessment of teeth without detectable MGJ
		Tooth number	Number of teeth, n (%)
Gingival recession	48 (52.7)	31	24 (26.37)
Pocket till MGJ	21 (23.1)	32	11 (12.08)
Abnormal habits	1 (1.1)	33	4 (4.39)
Malpositioned tooth	7 (7.7)	41	22 (24.17)
Trauma	0	42	16 (17.58)
Severe abrasion	8 (8.8)	43	3 (3.29)
Abnormal frenal attachments	6 (6.6)	13	2 (2.19)
Any other	0	Other teeth	9 (9.89)
Total	91 (100)	Total	91 (100)

MGJ – Mucogingival junction; n – number of

Graph 1.

Comparison of etiology for the absence of mucogingival junction. MGJ – Mucogingival junction

Table 3.

Absence of mucogingival junction on individual teeth as correlated with etiology

Etiology	Incisors, n (v %), [h %]	Canines, n (v %), [h %]	Premolars, n (v %), [h %]	Molars, n (v %), [h %]	Total, n [%]
Gingival recession	41 (54.7) [85.4%]	7 (58.3) [14.6%]	0	0	48 [100]
Pocket till MGJ	21 (28) [100%]	0	0	0	21 [100]
Abnormal habits	0	0	0	1 (100) [100%]	1 [100]
Malposed tooth	3 (4) [42.8%]	3 (25) [42.8%]	1 (33.3) [14.3%]	0	7 (100)
Trauma	0	0	0	0	0
Severe abrasion	4 (5.3) [50%]	2 (16.7) [25%]	2 (66.6) [25%]	0	8 [100]
Abnormal frenal attachment	6 (8) [100%]	0	0	0	6 [100]
Any other	0	0	0	0	0
Total	75 (100)	12 (100)	3 (100)	1 (100)	91

MGJ – Mucogingival junction; n – number of; (v %)- percentages of vertical column; [h %]- percentages of horizontal row

DISCUSSION

This study was a unique attempt to identify teeth that may not have MGJ as a normal anatomical feature. The study considered the presence of MGJ as a normal morphological feature present with all the teeth and evaluated it on the premise that we will be able to detect MGJ clinically in all the teeth. Bowers[10] reported a lot of variations in the width of attached gingiva: between males and females, between individuals, between teeth types, between positioning of teeth, between adjacent anatomical structures, etc., We did not find any directed study specifically to address the absence of clinically detectable MGJ in the literature, although the assessments are presented as zero width of attached gingiva in various studies on gingival recession or other periodontal plastic surgical procedures. The zero width of attached gingiva, immobile mucosa, or keratinized gingiva is an equivalent of the absence of MGJ. There will always be a sulcus bordered by marginal gingiva, or marginal tissue of other nature, like nonkeratinized tissue; which is not dependent per se on the presence or absence of MGJ. Specifically, the absence of MGJ is observed on the mid-buccal aspects of the involved teeth, and then, it becomes the most vulnerable part because of the attendant convexity and constant tension and pulls from the maxillofacial musculature. The study attempted to identify those cases and teeth without clinically detectable MGJ related to any etiology or even unrelated to any pathological condition. The pathological reasons for MGJ absence are well known, we may come across its physiological absence in the form of genetic or developmental departures, which was an additional benefit, as altered gingival contours have been observed in anodontia/hypodontia syndromes.[27]

The definitive presence of MGJ can only be assessed by histological examination, while the clinical assessment methods may be somewhat subjective, especially visual and TTs. We used four different clinical methods to detect MGJ on individual teeth on mid-buccal aspects to reduce the subjective bias. The presentation of the relative difference between the four assessment methods used is not the objective of this paper. A reliance on at least two methods showing the same result out of four solidified our definitive observation for the absence of MGJ.

Detecting the proper position of MGJ in relation to mucosal margin and base of the sulcus/pocket is one of the most important exercises for the majority of periodontal procedures. Assessment of the width of the attached gingiva is vital in assessing the risk of the periodontium to be affected by the disease. In the assessment of the width of the gingiva, the MGJ serves as an important anatomical landmark for measurements in periodontal evaluation. Assessment of gingival dimensions, including apico-coronal dimensions, is essential in decision-making in periodontal treatment planning, specifically to establish whether and what type of periodontal surgical procedure should be performed. Furthermore, proper identification of MGJ at a surgically altered mucogingival complex is crucial to determine the outcome following the periodontal procedure. Lang and Löe reported that plaque-free areas with <2.0 mm of keratinized gingiva were inflamed as evaluated with gingival index and gingival exudate measurements.[5] Thus, they concluded that 2.0 mm or more of keratinized gingiva (which corresponded to 1.0 mm or more of attached gingiva) is necessary to maintain gingival health. It has been observed that in the absence or following the removal of the attached gingiva, the remaining tissue (alveolar mucosa) curls. In addition, alveolar mucosa will not withstand the rigors of mastication or oral physiotherapy.

Although the detection of MGJ may correlate well with the presence of the attached gingiva, this study was not intended to measure the width of the attached gingiva irrespective of its presence. Animal studies by Wennström and Lindhe cleared much controversy regarding the width of attached gingiva (AG) and periodontal health.[28] It is clear that the apico-coronal width of AG is not significant to maintain health in a healthy or reduced periodontium around natural, unrestored teeth as long as plaque control is maintained. They established four different dentogingival units for studying this aspect:[28]

1. Normal attachment apparatus and normal width of attached gingiva

2. Normal attachment apparatus but narrow width of keratinized gingiva (no attached gingiva)

3. Reduced attachment apparatus with a narrow width of keratinized gingiva (no attached gingiva), and

4. Reduced attachment apparatus with normal/wide zones of attached gingiva (grafted sites).

As already mentioned in the beginning, studies reporting root coverage or gingival augmentation procedures mention the preoperative width of the attached gingiva. There are hardly any subgroup analyses or individual patient data presented in these studies, as preoperative measurements of 0 mm (or 0–1 mm) of keratinized gingiva/mucosa indicate the absence of MGJ. Freedman et al. reported three sites with 0 mm keratinized gingiva 18 years after follow-up, which indicates the absence of MGJ. They also reported 19 sites preoperatively and 12 sites postoperatively having 1 mm of keratinized gingiva.[29] We feel that identifying MGJ 1 mm apical to the gingival margin is one of the most difficult tasks with any of the clinical methods employed for MGJ identification. The transition from immobile tissue to mobile tissue at 1–2 mm from the gingival margin will always remain highly subjective, especially in presence of even mild degree of inflammation. These may influence the dependability of findings regarding AG and keratinized gingiva (KG) measurements of various studies. Only two anatomic situations actually define the absence of MGJ, presence of only attached gingiva/mucosa on palate, and presence of only alveolar mucosa. There cannot be an endless presence of attached gingiva on buccal and mandibular lingual aspects, so that can be defined by alveolar mucosa presence only.

Wennstrom was involved in doing some unique studies going beyond MGJ. For studying the regeneration of gingiva and association of lack of attached gingiva with other conditions, he resected the keratinized gingiva beyond MGJ. He used Schiller's iodine solution on buccal mucosa to identify the MGJ, then an incision was made about 1 mm apical to this borderline (MGJ), and the knife was angulated in a coronal direction so that its tip reached the tooth at the level of the alveolar bone crest. Similar incisions were given on the lingual side, all the gingiva tissue and connective tissue were removed, but periosteum was maintained. This is akin to a surgically created absence of MGJ.[30,31]

There are no parallels of this study, which is the reason we are unable to analyze our results vis-a-vis other similar investigations. Gliksberg et al.[32] attempted to establish how often mucogingival defects occur in a random population sample. Fifty-two patients (with 25 average teeth) were evaluated for the presence or absence of mucogingival defects among any surfaces. The MGJ was determined using illumination and a tongue blade based on the difference between gingival and alveolar mucosa in clinical appearance. The width of keratinized gingiva was determined and an area was considered as having a mucogingival defect if the zone of attached gingiva was zero. Out of 1302 teeth, just 13 (1%) teeth had mucogingival defects or lack of attached gingiva. Thus, it can be considered that they found 1% of teeth with the absence of clinically detectable MGJ.[29] Out of a total of 3637 teeth examined, our study found 2.5% of teeth without clinically detectable MGJ. Considering our study subjects and design of the study, this distribution seems more than plausible. The subjects visiting the department of periodontology are expected to have more periodontal problems than others. The majority of the teeth (69 out of 91/76%) with no MGJ were related to periodontitis. The other minor reasons for the same were malpositioned teeth, severe cervical abrasion, and high frenal/muscle attachments.

It is a well-known fact that periodontitis in mandibular anterior teeth most often leads to horizontal destruction of the periodontium. This may be the reason why the tooth type distribution showed involvement of lower anterior teeth (canine to canine) in 88% of cases. Lower central incisors were the most affected teeth, followed by lower lateral incisors. The prevalence of absence of MGJ on posterior teeth (premolars and molars) is negligible for any specified reason. All the molars and premolars were related to abrasion, malpositioning, and abnormal habits. No posterior tooth showed an absence of MGJ secondary to periodontitis reasons, which may be attributed to vertical tissue loss rather than horizontal tissue loss as happens with incisors, and our utilization of 4 identification methods.

Thirty-two subjects out of 130 showed the absence of MGJ on one or more teeth. Thus, the population prevalence of subjects without clinically detectable MGJ turns out to be 24.6%. A larger study may be required to extrapolate this prevalence to the general population. The average number of teeth in subjects without MGJ is 2.8. The calculated prevalence of teeth without MGJ in our surveyed population comes out to be 0.7 (91/130). The low prevalence may represent true population prevalence as our target sample consisted of periodontally healthy as well as diseased individuals. This also suggests that the absence of MGJ by direct involvement in periodontitis patients is very low.

CONCLUSION

With due limitations and drawbacks of this first attempt of identifying teeth with the absence of clinically detectable MGJ on the mid buccal aspect of teeth, we conclude that the prevalence of such teeth is much less with at the most one tooth affected in 25% of the observed population. The population prevalence of such teeth is found to be 25%, and the affected tooth/teeth prevalence is 0.7 tooth/mouth, with the majority of teeth affected are mandibular central incisors. A larger sample size study is needed to confirm the results unequivocally. A clinician should consider identifying and recording a tooth or teeth without detectable MGJ, especially mandibular central incisors, observe the position of marginal tissue over a period of time, and intervene surgically whenever necessary.

The MGJ is a normal and regular anatomic finding and its absence is almost always related to pathological processes. The developmental absence of MGJ is related to abnormal frenal/muscle attachments and vestibular eruption of teeth. The genetic influence for its absence looks to be inconsequential.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.