Maxillary labial frenum morphology and midline diastema among 3 to 12-year-old schoolgoing children in Sri Ganganagar city

A cross-sectional study

Abstract

Introduction: 

Dentofacial aesthetics plays an important role in social interaction and psychological well-being because it affects how people perceive themselves and how they are perceived by society. The maxillary labial frenum is a fold of tissue, usually triangular in shape, extending from the maxillary midline area of the gingiva into the vestibule and mid portion of the upper lip. Maxillary anterior spacing or diastema is a common aesthetic complaint of patients and is frequently seen in children especially in the mixed dentition stage.

Aims and Objectives: 

1. To estimate the prevalence of different morphologic types of maxillary labial frenum among children of age 3 – 12 years. 2. To find out the relationship between the level of insertion of the frenum and age of the child.3. To evaluate the correlation between frenum morphology, insertion and midline diastema in children.

Materials and Methodology: 

The direct visual method under natural light was used and the upper lip was lifted with the index finger and thumb of both hands which allowed for the observation and classification of the labial frenum morphology according to Sewerin's typology and its attachment according to Placek et al. The midline diastema was determined by measuring the distance between the midpoints of the mesial surfaces of both central incisors with the help of divider and ruler. The values were recorded in the prepared schedule.

Summary and Conclusions: 

The presence of an abnormal frenum can be a cause in persistent midline diastemas. Tooth movement usually is deferred until eruption of the permanent canines but can begin early in certain cases with very large diastemas.

Introduction

Frenum is a fold of mucous membrane, usually with enclosed muscle fibers, that attaches the lips and cheeks to the alveolar mucosa and/or gingiva and the underlying periosteum.[^1,2] Frenum's primary function is to provide stability of the upper and lower lips and the tongue.[³]

Within the first few months of fetal life, it emerges as a part of the oral cavity, along with the lips and the cheeks.[⁴] As growth and development progresses, a prominence begins to appear in the middle part of the inner zone of the upper lip, and this becomes the tuberculum. About this time, another prominence forms on the anterior part of the palate and develops into the palatine papilla.

A continuous fold of tissue, the tectolabial frenum, connects the tuberculum with the palatine papilla (tectolabial frenum of the fetus simulates the abnormal frenum of postnatal life, in that it extends as a continuous band of tissue from the inner aspect of the upper lip, over and across the alveolar ridge, to be inserted in the palatine papilla). Normally, the growing alveolar process causes a severance of the continuous fold of tissue, dividing it into palatal and labial portions. The palatal part corresponds to the palatine papilla, and the labial tissue becomes the superior labial frenum, extending from the lip to the crest of the alveolar ridge.[⁵]

There are no studies that establish a relationship between the different types of freni and the presence of the midline diastema in children in primary dentition. The most frequent frenum typology used is the one established by Sewerin.[⁶] According to Miller, the frenum should be characterized as pathogenic when it is unusually wide or there is no apparent zone of attached gingiva along the midline, or the interdental papilla shifts when the frenum is extended.[⁷]

Over the years, the relationship between the maxillary midline diastema and the labial frenum has been the subject of much controversy and confusion. In 1939, Hirschfield advocated frenectomy as a mucogingival procedure to eliminate the aforementioned pathologic situations caused by an abnormal frenum attachment.[⁸] There is still a controversy among researchers concerning the need for it at all, as well as the right time for frenectomy.

The aims and objectives of the present study are as follows:

1. To estimate the prevalence of different morphologic types of maxillary labial frenum among children aged 3–12 years
2. To find out the relationship between the level of insertion of the frenum and age of the child
3. To evaluate the correlation between frenum morphology, insertion, and midline diastema in children.

Materials and Methods

For this study, 1200 children aged 3–12 years from different schools of Sri Ganganagar city, Rajasthan, were enrolled. These students were categorized into three groups as follows:

• Group I: 3–5 years
• Group II: 6–9 years
• Group III: 10–12 years.

The direct visual method under natural light was used and the upper lip was lifted with the index finger and thumb of both hands, which allowed for the observation and classification of the labial frenum morphology according to Sewerin's[⁶] typology and its attachment according to Mirko et al.[⁹]

Sewerin's typology of maxillary labial frenum is as follows:

• Simple frenum – Frenum with nichum
• Persistent tectolabial – Bifid frenum
• Simple with appendix – Double frenum
• Simple with nodule – Frenum with two or more variations.

Attachment of labial frenum by Placek et al. is as follows:

• Mucosal
• Gingival
• Papillary
• Papillary penetrating.

The study population was selected based on the following inclusion and exclusion criteria.

Inclusion criteria

Schoolgoing children aged 3–12 years and children having normal dentition with no or minimal crowding.

Exclusion criteria

Children with any systemic illness, any orofacial syndromes, cleft lip abnormalities, congenital deformities relating to the upper lip and supporting oral musculature, those who have experienced any surgeries or traumatic injuries to the labial frenum, those with loss of maxillary anterior teeth following trauma, those with interproximal caries or restorations in the upper central incisors, those with any alterations in size and shape of the upper central incisors, and those with any type of previous interceptive and corrective orthodontic treatment.

Armamentarium

Mouth mirror, probe, tweezer (API), kidney tray, disposable gloves, disposable mouth masks, cotton roll and gauze pieces, Savlon (Johnson & Johnson Pvt Ltd, Tokai), torch, divider, and ruler.

Study design

The area of Sri Ganganagar was divided into four zones and all the schools present in Sri Ganganagar were divided accordingly.

• Zone I: East zone
• Zone II: West zone
• Zone III: North zone
• Zone IV: South zone.

From each zone, five schools were selected randomly and sixty children aged 3–12 years were selected randomly from each school. Then, the study program was started in those selected schools through proper channel.

Study setting

Clinical examination was carried out by the principal researcher. General intraoral examination was done by using a mouth mirror and explorer. Chemical method of sterilization and disinfection was done by using Savlon (Johnson & Johnson Ltd.) which contains chlorhexidine gluconate and a strong cetrimide solution equivalent to 0.6%. These instruments were sterilized by mixing 1 part of Savlon with 3 parts of water. The children were made to sit comfortably on the ordinary chair and clinical examination was carried out. The direct visual method under natural light was used and the upper lip was lifted with the index finger and thumb of both hands, which allowed for the observation and classification of the labial frenum, according to the Sewerin's typology.[⁶] The level of insertion of the maxillary labial frenum was also evaluated according to the classification proposed by Mirko et al.[⁹] It was noted in the schedule whether the frenum was attached to the alveolar mucosa, gingiva, interdental papilla, or penetrating incisive papilla. Blanching test was used to confirm the level of attachment.

Data were analyzed using the computer software, Statistical Package for the Social Sciences version 10 (Nie, Bent and Hull (1970), IBM corporation). Data were expressed in its frequency and percentage. To elucidate the associations and comparisons between different parameters, Chi-square (χ²) test was used as nonparametric test. One-way analysis of variance was performed as parametric test to compare different variables. For all statistical evaluations, P < 0.005 was considered statistically significant.

Results

Table 1 shows the sample characteristics, and the study population was divided into three groups, namely 3–5 years, 6–9 years, and 10–12 years.

Table 1: Sample characteristics

Table 2 shows the prevalence of different morphologic types of maxillary labial frenum in the study sample. In the present study, the most prevalent morphologic type of maxillary labial frenum was the simple type. The number of simple, persistent tectolabial, simple with nodule, and simple with appendix frenum was 825 (68.7%), 184 (15.3%), 124 (10.3%), and 61 (5%) respectively. Double frenum and two or more variations at the same time were seen in 4 (0.3%) and 2 (0.16%) children, respectively.

Table 2: Prevalence of frenum by morphologic type

On assessing the types of maxillary labial frenum in different age groups, it was found that simple frenum showed the highest prevalence in 10–12 years' age group and persistent tectolabial type was more common in 3–5 years' age group [Table 3].

Table 3: Types of maxillary labial frenum in each age group

Table 4 depicts the level of insertion of maxillary labial frenum in the study, and it was found that the frenum was inserted into the alveolar mucosa in 571 (47.5%), in the gingiva in 458 (38.1%), and penetrating the incisive papilla in 171 children (14.2%). Maxillary labial frenum was seen inserted more frequently in the alveolar mucosa in children of 10–12 years' age group (58.3%). The gingival and incisive papillary insertion was more common in children of 6–9 years' and 3–5 years' age groups.

Table 4: Level of insertion of maxillary labial frenum in each age group

The relationship between morphologic types of maxillary labial frenum and level of insertion of frenum was evaluated, and it was found that the simple frenum was mostly inserted in the gingiva and alveolar mucosa and persistent tectolabial type penetrating the incisive papilla [Table 5].

Table 5: Association between maxillary labial frenum and level of insertion

In the present study, the midline diastema was measured, and it was found that out of 1200 children, 501 children (41.75%) presented with a midline diastema >0.5 mm. To further evaluate midline diastema, children were divided into three groups, i.e., mild (0.5–1.5 mm), moderate (1.6–2.5 mm), and severe (>2.5 mm) [Table 6].

Table 6: Distribution of midline diastema

The prevalence of midline diastema in each age group was assessed, and it was found that midline diastema was more in the 6–9 years' age group [Table 7].

Table 7: Association between midline diastema and age

The relationships between morphologic types of maxillary labial frenum and midline diastema were assessed in the study, and it was found that among children with midline diastema, 52.6% had simple frenum and 35.9% had persistent tectolabial frenum. Midline diastema >2.5 mm was more prevalent with persistent tectolabial type of frenum.

The relationships between morphologic types of maxillary labial frenum and midline diastema were assessed in the study, and it was found that among children with midline diastema, 52.6% had simple frenum and 35.9% had persistent tectolabial frenum [Table 8].

Table 8: Association between maxillary labial frenum and midline diastema

Table 9 predicts the relationship between the level of insertion of maxillary labial frenum and midline diastema, and it was found that diastema >2.5 mm was more common in children with frenum penetrating the incisive papilla.

Table 9: Association between level of insertion and midline diastema

Discussion

Sewerin's typology was used in classifying the frenum, and it was found that the most prevalent morphologic type of maxillary labial frenum was the simple type with the prevalence of 68.7% followed by persistent tectolabial frenum with the prevalence of 15.3%. Simple with nodule and simple with appendix type were seen in 10.3% and 5% of children, respectively. Similar results were reported in the studies by Díaz-Pizán et al.[¹⁰] and Alessandra et al. (2007)[¹¹] where the simple upper labial frenum showed the highest prevalence followed by the persistent tectolabial, simple with nodule, simple with appendix, double, coincidence of two or more variations or abnormalities, and frenum with nichum and bifid types.

In the present study, the types of maxillary labial frenum in different age groups were assessed, and it was found that simple frenum showed the highest prevalence in 10–12 years' age group and persistent tectolabial type was more prevalent in 3–5 years' age group. These findings are in consistent with the results of the studies conducted by Walter[¹²] and Díaz-Pizán et al.[¹⁰]

In the present study, in 47.6% of children, the frenum was inserted into the alveolar mucosa; in 38% of children, it was inserted in the gingiva; and in 14.4% of children, it was seen penetrating the incisive papilla. Similar findings were reported in the study by Alessandra et al. (2007)[¹¹] who studied the frenum attachments and found that the attachments to alveolar mucosa were the most prevalent followed by insertion in the gingiva, interdental papilla, and penetrating the incisive papilla.

In the present study, the level of gingival insertion was seen differing according to the age. Maxillary labial frenum was seen inserted more frequently in the alveolar mucosa in 10–12 years' age group (58.3%). The gingival and papillary insertion was more common in 3–5 years' and 6–9 years' age groups. In the study on maxillary labial frenum morphology, Díaz-Pizán et al.[¹⁰] reported that the level of gingival insertion of frenum moved apically with age. This corroborates with the findings of the present study. The relationship between maxillary labial frenum morphology and level of insertion of frenum was evaluated in the present study, and was found that the simple frenum was mostly inserted in the gingival and alveolar mucosa, with persistent tectolabial frenum penetrating the incisive papilla. Simple frenum with appendix and nodule were mainly inserted in the alveolar mucosa.

The prevalence of midline diastema in the sample population was found to be 41.75%. Midline diastema was divided into three groups: mild (0.5–1.5 mm), moderate (1.5–2.5 mm), and severe (>2.5 mm). Mild diastema was seen in 18.75% of children, moderate in 15.5%, and severe in 7.5% of children. Longitudinal studies of Bergström et al.,[¹³] Popovich et al.,[¹⁴] Taylor,[¹⁵] and Weyman[¹⁶] confirm the hypothesis that the midline diastema is decreasing with increasing age of the individual and higher prevalence was mostly seen before the eruption of the lateral incisors. Richardson et al.[¹⁷] concluded in their study that the highest prevalence of diastema was found to be at the 8-year age level. The prevalence increased from 6 years to 8 years and it gradually decreased by 14 years.

In the discussion about the relationship between diastema and frenum, authors like Angle,[¹⁸] Taylor,[¹⁵] Dewel,[¹⁹] Vono et al.,[²⁰] Edwards,[²¹] Araujo and Bolognese[²²] argued that the low insertion or abnormal frenum is responsible for the midline diastema. A study by Baume (1950)[²³] reported that the abnormal frenum is the result of diastema while pressure from the adjacent teeth is insufficient to produce its atrophy. Studies by Ceremello[²⁴] have demonstrated the independence of maxillary labial frenum and midline diastema.

Conclusion

The following conclusions were derived from the results of the study:

1. The most prevalent morphologic type of maxillary labial frenum was the simple type which increased significantly with age followed by persistent tectolabial frenum which decreased significantly with age (P < 0.001)
2. The commonest location of frenum attachment was alveolar mucosa followed by gingiva and papillary penetrating incisive papilla. The level of insertion tends to move apically and thus the prevalence of insertion into the alveolar mucosa increased significantly with age (P < 0.001)
3. The prevalence of midline diastema in the sample population was found to be 42.2% and midline diastema was more prevalent in the 6–9 years' age group. The prevalence of midline diastema decreased significantly in children with erupted permanent canines
4. A statistically significant relationship was found between midline diastema and persistent tectolabial frenum and a significant inverse relationship was found between the level of gingival insertion and midline diastema (P < 0.001).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.