Discussion
The lingual frenulum guides tongue development and growth
in utero, during fetal development, and after birth [
4]. Alteration in the lingual frenulum can cause abnormal tongue movement leading to alteration in surrounding structure development, such as in orofacial dysmorphosis [
5]. Jang
et al. found that people with skeletal class III malocclusion have a longer lingual frenulum. They also found that the longer the lingual frenulum, the less the degree of mouth opening [
6]. After development is completed, the lingual frenulum usually does not extend to the tip of the tongue; it only stabilizes the tongue without causing any interference to tip movement [
1].
Walker
et al. found that the average length from the tongue tip to the insertion of the lingual frenulum in the base of the tongue is between 9 and 10 mm in newborns [
7]. The shorter the distance (ankyloglossia), the more problems will be associated, such as difficulties in breastfeeding [
7,
8], difficulties in newborn sucking [
8], speech impediments [
9], teeth malocclusion, maxillary constriction, anterior open bite, spacing in the lower incisors [
10], obstructive sleep apnea [
5], poor oral hygiene, and being embarrassed by peers [
11].
The prevalence of ankyloglossia is 4.2–10.7% [
11]. Yet, until now, diagnosing ankyloglossia has been considered difficult due to lack of a standard test. The most common measurements of ankyloglossia were provided by Kotlow and Ruffoli [
12,
13]. Kotlow classified the ankyloglossia according to the length of free tongue, from the tongue tip to the insertion of the lingual frenulum in the ventral surface of the tongue [
12]. Ruffoli
et al. classified the ankyloglossia by measuring the maximum opening of the mouth with the tip of the tongue touching the palatal papilla [
13]. Other recent studies, such as one by Segal
et al., listed the criteria used to diagnose ankyloglossia in studies from 1982 to 2005, but none of the studies assessed internal and external validity [
11]. Ingram
et al. used a Bristol Tongue Assessment Tool as a simple indication for the severity of ankyloglossia but did not assess what level of severity would benefit from the treatment [
14]. Yoon
et al. set a functional tongue range of motion ratio grading scale to define ankyloglossia and the need for surgical treatment, and further studies in this area are needed [
4]. Brandão
et al. used the Neonatal Tongue Screening Test for detecting ankyloglossia, but it was neither reliable nor valid [
15]. Ankyloglossia is usually treated by simple frenectomy, cutting of the lingual frenulum. Studies revealed a positive effect on breastfeeding [
16‐
19], but no other studies reported its effect on other tongue-tie problems.
Another known anomaly is absence of the lingual frenulum. It can be seen sporadically or associated with other conditions [
3]. It is commonly seen in patients with Ehlers-Danlos syndrome. Literature has suggested that absence of the lingual frenulum can be a simple method of early diagnosis of Ehlers-Danlos syndrome [
2,
20]. One more variation reported is posterior lingual frenulum. Martinelli
et al. stated that, to differentiate between posterior lingual frenulum and absence of lingual frenulum, elevating and pushing the tongue back is required [
21]. In our patient’s case, the double lingual frenula required no diagnostic tools other than proper clinical examination, and no intervention was needed, because both frenula did not extend to the tip of the tongue or interfered with the tongue function.
The literature shows few case reports and variations in the labial frenum, such as frenum with a nodule, double frenum, multiple frenula, and high frenum attachment, but no similar literature was found regarding the lingual frenum, except for ankyloglossia, the absence of lingual frenum, and posterior lingual frenum [
22‐
24].
Some syndromes are characterized by supernumerary frenula, such as orofacial-digital syndrome, Pallister-Hall syndrome, and Opitz trigonocephaly C syndrome [
22]. However, no literature has ever reported specifically double lingual frenula in any of these syndromes. In addition, our patient did not report any suspicious features of any of these syndromes.
The cause of lingual frenulum variation, including ankyloglossia, absence of lingual frenulum, and posterior lingual frenulum, is unknown, so this is also the case for the double lingual frenulum in our patient.
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