|Year : 2014 | Volume
| Issue : 1 | Page : 16-20
Proposed classification of medial maxillary labial frenum based on morphology
Ranjana Mohan1, Pankaj Kumar Soni1, Munagala Karthik Krishna1, Mohan Gundappa2
1 Department of Periodontology, Teerthanker Mahaveer Dental College and Research Centre, Moradabad, Uttar Pradesh, India
2 Department of Consertive Dentistry and Endodontics, Teerthanker Mahaveer Dental College and Research Centre, Moradabad, Uttar Pradesh, India
|Date of Web Publication||3-Mar-2014|
Department of Periodontology, Teerthanker Mahaveer Dental College & Research Centre, Moradabad - 244 001, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Objectives: To propose a new classification of median maxillary labial frenum (MMLF) based on the morphology in permanent dentition, conducting a cross-sectional survey. Materials and Methods: Unicentric study was conducted on 2,400 adults (1,414 males, 986 females), aged between 18 and 76 years, with mean age = 38.62, standard deviation (SD) = 12.53. Male mean age = 38.533 years and male SD = 12.498. Female mean age = 38.71 and female SD = 12.5750 for a period of 6 months at Teerthanker Mahaveer University, Moradabad, Northern India. The frenum morphology was determined by using the direct visual method under natural light and categorized. Results: Diverse frenum morphologies were observed. Several variations found in the study have not been documented in the past literature and were named and classified according to their morphology. Discussion: The MMLF presents a diverse array of morphological variations. Several other undocumented types of frena were observed and revised, detailed classification has been proposed based on cross-sectional survey.
Keywords: Appendix, bifid, classification, frenum, median maxillary labial, nodule, tectolabial, trifid
|How to cite this article:|
Mohan R, Soni PK, Krishna MK, Gundappa M. Proposed classification of medial maxillary labial frenum based on morphology. Dent Hypotheses 2014;5:16-20
| Introduction|| |
Frenum can be defined as "a fibrous band of tissue attached to the bone of the mandible and maxillae, and is frequently superficial to muscle attachments."  The frenii of the oral cavity are categorized into different types: Frenulum linguae, under the tongue; the frenulum labii superioris, inside the upper lip; the frenulum labii inferioris, inside the lower lip; and the buccal frena which connect the cheeks to the gingiva.  The frenulum labii superioris or median maxillary labial frenum (MMLF) is found on the underside of the center of the upper lip that connects to the midline of the attached gingiva between the central incisors. The origin is often wide but the tissue of the frenum itself narrows in width and is inserted in the midline into the outer layer of periosteum, and into the connective tissue of the intermaxillary suture and the alveolar process.  A normal frenum attaches apically to the free gingival margin so as not to exert a pull on the zone of the attached gingiva and usually terminating at the mucogingival junction. However, its level may vary from the height of vestibule to the crest of the alveolar ridge and even to the incisal papilla area in the anterior maxilla. , Several classifications for frena based on morphology have been proposed, the Modified Sewerins Topology being the most cited one. , However, this classification may not be adequate, especially in the aspect of the MMLF, as several variations in its morphology have been observed which have not been classified till date. Many dentists are not aware of the variations of MMLF, misinterpreting them as pathological entities. Certain degree of confusion exists in classifying frena types, leading to difficulties in diagnosis and treatment planning. Aberrant frena often cause problems such as loss of papilla, recession, diastema, difficulty in brushing, alignment of teeth, and psychological disturbances.  Morphological variations of MMLF need to be addressed, differentiating them from abnormal ones during various dental procedures. The present study aims to propose a detailed and revised classification of normal MMLF based on morphology.
| Materials and Methods|| |
A prospective, cross-sectional unicentric study was undertaken for a period of 6 months at the Campus of Teerthanker Mahaveer University, Moradabad, Uttar Pradesh, one of the most populous states of Northern India, where pupils hail from all over the country with all religions, income groups, married and unmarried, and with different languages. Since the study did not involve any treatment and was mainly based on mere examination of frenum, convenience sampling was used for sampling methodology. Probabilistic sampling does not seem to be providing any improvement in observations or the accuracy of the study. The subjects included anyone from students, to staff members, and even patients attending the Dental Outpatient Department and the Department of Periodontology at Teerthanker Mahaveer University campus, Moradabad, India, who were willing to participate. There was no limit on the sample size, and hence the data was considered in such a way that the number of observations are to the nearest hundred digit. Study population included 2400 adults (1,414 males and 986 females) who were willing to participate in cross-sectional survey.
The study protocol was approved by the Teerthanker Mahaveer University Ethical Committee which is in accordance with Helsinki Declaration. Written consent was obtained from patients before enrolling them for the study. Patients with cleft lip/palate, congenital anomalies, or with a history of traumatic injuries to the labial frenum were excluded from the study. The frenum morphology was determined by using the direct visual method under natural light by reflecting the upper lip with index finger and thumb of both hands. To maintain consistency, all examinations were carried out by a single dentist.
Various morphological types of MMLF were observed in the study subjects based on which they were categorized into different types as follows: Simple frenum: Single [Figure 1]a, double [Figure 1]b, and triple [Figure 1]c; tectolabial frenum: Simple [Figure 2]a, with nodule [Figure 2]b, and with appendix [Figure 2]c; frenum with nodule: Labial third [Figure 3]a, middle third [Figure 3]b, alveolar third [Figure 3]c, and multiple [Figure 3]d; frenum with appendix: Labial third [Figure 4]a, middle third [Figure 4]b, and alveolar third [Figure 4]c; frenum with nichum [Figure 5]a, inverted 'Y' frenum [Figure 5]b, bifid frenum [Figure 5]c and trifid frenum [Figure 5]d.
|Figure 2: Tectolabial frenum: (a) Simple, (b) with nodule, and (c) with appendix|
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|Figure 3: Frenum with nodule: (a) Labial third, (b) middle third, (c) alveolar third, and (d) multiple|
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|Figure 4: Frenum with appendix: (a) Labial third, (b) middle third, and (c) alveolar third|
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|Figure 5: New frenal types: (a) With nichum, (b) inverted 'Y', (c) bifid, (d) trifid|
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The actual and percentage-wise distribution of MMMF types was calculated. The obtained data was subclassified based on gender prevalence.
| Results|| |
Study population included 2,400 adults (1,414 males, 986 females) with all religions, income groups, and languages who were willing to participate in cross-sectional survey at the campus of Teerthanker Mahaveer University, Uttar Pradesh, one of the most populous states of India. The study included only the examination of Frenum morphology based on convenience sampling. A total of 2,536 individuals were approached, out of which 2,400 agreed to participate in the study and aged between 18 and 76 years with mean age = 38.62 years, standard deviation (SD) = 12.53. Male mean age = 38.533 years and male SD = 12.498. Female mean age = 38.71 years and female SD = 12.5750. The most common type of MMLF observed was the simple single frenum (63.79%) followed by frenum with nodule (19.92%) and frenum with appendix (6.38%). Among the frena with nodule, majority of them had the nodule at middle one-third position (8.04%) and in the case of frena with appendix, majority of appendices were found at labial one-third position (2.79%). Simple tectolabial frena were observed in 5.2% of the patients. Other types of MMMF observed based on the Modified Sewerins Typology  were the frenum with nichum (0.5%) and bifid frenum (0.5%). Frenum types not previously classified and observed in the present study were the simple triple frenum (1.57%), frenum with multiple nodules (1.58%), tectolabial frenum with nodule (0.29%), tectolabial frenum with appendix (0.12%), inverted 'Y' frenum (0.29%) [Figure 5]b], and trifid frenum (0.58%).
Two or more frenal variations and absence of frenal attachment were not detected in the study subjects as shown in [Table 1].
|Table 1: Overall distribution and percentage values of median maxillary labial frenum (MMLF) types|
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On comparison of the distribution patterns of MMLF types based on sex, the tectolabial frenum with nodule and inverted 'Y' frenum showed a significantly higher prevalence in male patients; whereas, the bifid frenum showed higher prevalence in female patients. No significant differences in sex distribution were found in the other types of MMLF as depicted in [Table 2].
|Table 2: Distribution pattern of median maxillary labial frenum (MMLF) based on gender|
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Based on the morphological variations observed, a revised classification of MMLF has been proposed as mentioned in [Table 3].
|Table 3: Revised classification of median maxillary labial frenum (MMLF) in comparison to Modified Sewerins Typology |
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| Discussion|| |
MMLF appears as a fold of mucous membrane extending from the mucous lining of the mucous membrane of the lips towards the crest of the residual ridge on the labial surface.  Several morphological variations of MMLF are being observed in day-to-day practice which is not documented in the literature. Need of the hour is to properly classify them in various categories in order to address them while performing various dental procedures.
The present study was conducted on 2,400 adults ageing 18-76 years, in the campus of Teerthanker Mahaveer University, Moradabad, Uttar Pradesh, one of the most populous states of India, to determine the morphological variations of MMLF. One-third of the subjects had variations in the MMLF morphology other than the simple single frenum suggesting that diverse variations may occur commonly in general population and are usually considered to be developmental in nature and not pathological as previously believed.  However, the presence of abnormal frena have been reported in the literature as a feature of syndromic conditions such as Ehlers-Danlos syndrome, infantile hypertrophic pyloric stenosis, holoprosencephaly, Ellis-van Creveld syndrome, and oro-facial-digital syndrome. 
Within the limitation of the study, conducted at one place, factors like different geographical regions, races, etc., could not be considered. To overcome the shortcoming, University campus having more than 10,000 adults residing in it hailing from every corner of the country with all religions, income groups, and languages was selected. Many other factors do not seem to be influencing the morphology of frenum.
In the present study, most commonly observed MMLF type was the simple single frenum (63.79%). Previous studies conducted on the prevalence of frenal types have reported a similar occurrence of simple single frenum. , Sewerin in Denmark, observed 60.2% of patients had a simple frenum.  In a recent study conducted by Townsend et al., on Caucasians and African-Americans, the prevalence of simple single frenum was 6.86%.  Present study observed majority of the nodules in the middle third of the frenum, whereas appendices were most commonly found in the labial third. Similar findings were reported in the studies by Sewerin and Townsend et al. These observations suggest that despite the differences in the ethnic and racial backgrounds, the pattern of distribution of MMLF variations maybe similar. Absence of frenum and two or more variations of any type of frenum were not found by author in any of the adults examined that is consistent with the previous studies. However, Kakodkar et al., conducted study on frenal attachments in 1,206 school going children; found a single case of "absent frenum" in a female.  This suggests that absent frenum is a very rare occurrence and maybe related to developmental abnormality.
Various classifications of MMLF have been mentioned in the literature based on its attachment and morphology. , Based on the level of attachment, frena have been classified as mucosal, gingival, papillary, and papilla penetrating.  However, the present study reveals several variations of MMLF that have not been reported till date. These include the simple triple frenum, frenum with multiple nodules, inverted 'Y' frenum, and the trifid frenum. In addition, tectolabial frena were found with appendices and nodules. Reports of frenal anamolies causing difficulties in speech, mastication, esthetics, and maintenance of oral hygiene have been well-documented in the literature. , MMLF is considered to be a complicating factor in denture construction. Frenal variations with a broad base migrated near the crest of the residual ridge; require early recognition and surgical removal for a more satisfactory treatment outcome with complete dentures. They also require the placement of large or multiple notches in dentures which have been considered responsible for fracture of many dentures. In such cases, it is preferred to fabricate a cast partial denture to prevent fracture.  Hence, proper identification of frenal variations and subsequent modification of treatment procedures are vital for a successful outcome of therapy.
The MMLF presents a diverse array of morphological variations. Several types of frena other than those documented in the published literature were observed in the present study. Hence, the detailed and revised classification of MMLF has been proposed based on morphology.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]
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