Tongue-Ties, Oh My!

Tongues out!

I’ve decided to focus on the TONGUE for the purpose of this post. I recognize that the tongue is a crucial muscle that lends to both orthodontic and orthopedic forces (or lack thereof) from the beginning of birth and onwards. So let’s talk about the tongue; why might an orthodontist care about the tongue?!

Here’s a personal life timeline of how I ended up here focusing on the tongue (you can skip this paragraph if you want to get to the good stuff!). I’ve not only had a long-time nerdy obsession over teeth (starting at age 5… yes… it’s true!), but I’ve been fascinated by sleep medicine since I was 14. My first “ever” literature review was on sleep disorders. A couple years later I did my own research project (with a statistician and all!) during my senior year of high school on the effects of adolescent sleep deprivation on mood and cognition. As a logical continuation, I worked at Dr. Mary Carskadon’s renowned sleep research lab in college, analyzing brain and facial muscle patterns during clinical sleep deprivation studies. I participated in what was called the Dement Fellowship back in 2005 and was privileged to meet Dr. Dement himself, who was one of the founders to establish sleep medicine as a field. This experience led to me pursuing obstructive sleep apnea oral appliance therapy research twice in Sydney (it was a collaboration between Harvard Med/Dental and the University of Sydney orthodontic and respiratory medicine departments!), which blended my two passions. This research also led to two publications in Chest (2011) and the AJODO (2019): if you ever want to check them out let me know, references are below! I even measured the tongue back then for research purposes, but then it kind of fizzled into the background, to be candid. The tongue is not a central focus in orthodontics or dentistry, and I hope to help in changing that. Long story short, I have a long-time passion for the interconnectivity of sleep, airway and dentistry, and I’m bringing the tongue back into the foreground!

I wrote a lot of posts in the past where I discuss the airway in relationship to dentistry/orthodontics. So feel free to check those as a reference; meanwhile, for now I will focus on the tongue, tongue-ties and interventions. Lastly, while most of what I've written here alludes to pediatric and/or early in life diagnostics and treatment, please keep in mind adult-intervention is also an equally important consideration (as these matters were not necessarily addressed years ago) 😊

THE TONGUE

Let’s first define the tongue. The tongue is a facial muscle: and according to Melvin Moss’ functional matrix theory (1968), where form follows function, muscles will directly influence skeletal growth. Dr. Mew (1979) discusses that the facial bones appear to be less under strict genetic control compared to the rest of the skeleton. The tongue and buccinator (cheek) muscles, in equilibrium, are responsible for establishing well-proportioned arch widths of the maxilla and mandible (Srinivasan and Chitharanjan, 2013). An untethered tongue is freely mobile and provides adequate pressure to the jaw to support craniofacial growth in all three dimensions. Resting tongue and lip postures are considered more important than in their action (such as during swallowing), according to Proffit (1978) and Mew (1979). Thus, long-term contact of the tongue against the palate is important in maxilla growth and development. More on this later.

TONGUE TIES: AN INTRODUCTION

When the underside of the tongue attaches to the floor of the mouth abnormally (i.e. too short and tight), tongue mobility may be impeded. This congenital condition known as ankyloglossia (AKA a tongue tie), is also referred to as a restrictive lingual frenulum or tethered oral tissue. According to Yoon et al. (2017), ankyloglossia occurs in about 4.8% of newborns. Meanwhile, Srinivasan and Chitharanjan (2013) cite that tongue ties may have a prevalence of 4.2-10.7% in the overall population, with a mild male predilection (1.5:1), and is inherited as an autosomal dominant condition. Jamilian et al. (2014) also found that ankyloglossia was more common in males. An un-split frenulum may physically adapt or stretch with age and could improve without intervention.

Messner et al. (2020) sought to create a consensus on defining anterior and posterior tongue ties (see image):

(A) An example of “anterior” ankyloglossia with the lingual frenulum attaching at the tongue tip, limiting tongue mobility. (B) Posterior attachment of lingual frenulum. Consensus was not reached regarding the definition of “posterior” ankyloglossia. Some in the consensus group would describe this figure as an example of posterior ankyloglossia if there are objective findings of restricted tongue mobility caused by the lingual frenulum. (Adapted from Messner et al., 2020)

Per Messner et al. (2020), more children are being diagnosed with ankyloglossia in recent years due to (1) an increased focus on the benefits of breastfeeding; (2) an increased awareness that ankyloglossia may negatively affect breastfeeding; (3) an increase in the number of lactation consultants who identify infants with possible ankyloglossia; (4) an increase in social media and websites related to tongue-tie, and (5) an increase in the number of medical practitioners, particularly dentists, who treat ankyloglossia. It has been shown that children who breast fed 6+ months had decrease overjet, wider intercanine/molar widths, decreased likelihood for malocclusion (D’Onofrio, 2019). Please also feel free to refer to the literature review I wrote on breastfeeding (both risks and benefits) last fall!

In terms of categorizing severity, there are different classifications which are based on a tongue range of motion ratio (TRMR). Grade 1 is defined as > 80% motion, while grade 2 is 50-80% motion, grade 3 is 25-50% motion, and grade 4 is < 25% motion.

(Adapted from Yoon et al. 2017)

Treatment for tongue ties may be provided through a lingual frenectomy, which is a surgical removal of the tethered tongue tissues and is commonly achieved via laser or scalpel incision. However, like with many procedures, it is equally as important to follow-up with a rehabilitation period – which is where a myofunctional therapist comes into play. On a personal note, I have noticed SO many patients (adult and pediatric alike) who are presenting with tongue-ties. Some of the adults have had orthodontics MORE than once and still experience significant orthodontic relapse. This is because the root cause of their malocclusions has not been addressed. Based on this literature review, I am even more certain that aberrant tongue motor behaviors are a huge contributor to dental/skeletal malocclusions and sleep-disordered breathing.

TONGUE TIE CONSEQUENCES

According to Zaghi (2019), a restrictive lingual frenulum is also a part of a phenotype of obstructive sleep apnea in both children and adults. Tongue ties in infancy may lead to difficulties with breastfeeding, growth/development and potentially cognitive and behavioral disturbances (Nammour, 2019). Decreases in tongue mobility have also been associated with narrowing of the maxillary arch and elongation of the soft palate (Yoon et al., 2017). The tongue will thrust anteriorly or laterally instead of upward against the hard palate during movements such as swallowing (D’Onofrio, 2019).

Maxillary constriction will thus also lead to narrowing of the nasal cavity, and may contribute to nasal obstruction, mouth-breathing and sleep-disordered breathing. Meanwhile, a decreased level of tongue mobility (or higher TRMR grade as referenced earlier) was associated with decreased interarch widths, i.e. a narrow archform, and a longer soft palate length as well as a high-arched palatal vault. Increased soft palate length has been an established risk factor in upper airway collapsibility and seen in OSA patients, as well (Yoon et al., 2017). The authors summarized that they believe tongue ties may contribute to open mouth-breathing and/or altered swallowing patterns that supports soft palate elongation.

Let’s now review a little bit about tongue ties, teeth and malocclusions. Sepet et al. (2015) postulated a significant relationship between the lingual frenum length with lower incisor irregularity. I’m sure it contributes to dental relapse, as well (maybe why us orthodontists retreat so many cases in adulthood; food for thought). Srinivasan and Chitharanjan (2013) discuss that a protrusive chin in ankyloglossia patients may be due to a low resting tongue posture, which causes the mandible to grow more anteriorly/forward. This may also be a potentiating contributor to an existing genetic etiology for a class III malocclusion. Interestingly, Jang et al. (2011) found that lingual frenulum lengths were significantly longer in skeletal class III subjects compared to class I/II. Furthermore, maximum mouth opening was significantly reduced in those with a class III malocclusion.

In additional Huang et al. (2015) illustrated that children with short lingual frenula were associated with abnormal (i.e. mouth) breathing and increased airway collapsibility during sleep, adenotonsillar hypertrophy, as well as a high and narrow palatal vault. The authors note these changes may be critical in the first two years of life, which is a period of rapid craniofacial growth.

Why may mouth-breathing lead to enlarged tonsils? Air as it passes through the nose (i.e. in an obligate nose-breather) will be humidified, warmed and have the airflow velocity regulated before it reaches the upper airway. Mouth-breathing, on the other hand increases upper airway resistance and causes micro trauma to the back of the throat. This may lead to inflammation of the tonsils, and ultimately their enlargement (Huang et al., 2015). Mouth-breathing is additionally associated with clockwise rotation of the mandible, increased lower anterior facial height, as well as lengthening of the pharynx which poses an increased risk of OSA (D’Onofrio, 2019). This is based on a physics principle wherein an increased tube length is correlated to increased resistance to flow (airflow in this case).

Fortunately, expansive orthodontics and orthopedics may help reverse some of these effects. Rapid palatal expansion, for instance, has been shown to improve resting tongue posture and convert mouth breathers to nasal breathers. Iwasaki et al. (2013) show that, in children with nasal obstruction, RPE offers significant improve in obstruction in addition to raising resting tongue posture and pharyngeal airway enlargement. Ozbek et al. (2009) also demonstrated improved tongue posture as well as a reduced hyoid bone-to-mandibular plane distance following RPE treatment. This second measurement is a cephalometric (x-ray) linear measurement that has been correlated with obstructive sleep apnea, particularly when the distance increases. Quality of life scores in high risk children for sleep disordered breathing improved 14% with RPE treatment, as well (Katyal et al., 2013). In terms of neuromuscular adaptations, Küçükkeleş and Ceylanoğlu (2003) demonstrated that the tongue takes longer to adapt compared to the lips and cheeks, when evaluated at the end of three-month’s retention.

Meanwhile, a study by Defabianis (2000) presented a patient who experienced spontaneous upper arch expansion after a lingual frenectomy, even without orthodontic treatment. To be fair though, this was just a single case, but still a pretty cool observation! So let us segue into discussing tongue tie intervention.

TONGUE TIE TREATMENT

Let’s conclude with some information about tongue tie treatment, also known as a frenectomy, frenotomy or frenulotomy, as well as myofunctional treatments to establish long-term postoperative success.

According to the Canadian Agency for Drugs and Technologies in Health (2016), tongue tie release may be performed with a scalpel/blade, surgical scissors or more recently with laser, which seems to be more accurate and decrease inflammation and postoperative pain and bleeding. This leads to better psychological feedback from patients (Nammour, 2019). A frenuloplasty (also known as Z-plasty) is a release conducted with anesthetic with a specific design of incision and wound closure that aims to lengthen the anterior tongue. A simple release does not include suturing and is performed usually without anesthetic. However, on the downside, if performed without suturing Nammour noted a risk of re-adhesion with tissue that is even more fibrous. This makes future retreatment more challenging. Thus, a physical therapy period and muscular retraining is a very important piece to comprehensive treatment. (Image adapted from Baker and Carr, 2015).

The Canadian Agency for Drugs and Technologies in Health (2016) reviewed frenectomy risks, as well. In terms of procedural caveats, the most commonly reported harm was bleeding, reoperating, scarring and pain. Case reports of surgical site infection, swelling, mucous cyst and hemorrhagic shock were seen when performed by an untrained worker. Generally speaking, the agency concluded there is probable benefit and minimal harm, and that frenectomy procedures are a viable treatment for infants to improve breastfeeding capacities.

Let’s talk about some improvements recognized as a result of a frenectomy. According to Messner and Lalakea (2002), significant improvements were made in tongue protrusion and elevation measurements after undergoing a frenectomy. Articulation problems due to ankyloglossia improved in the majority of the children in their study, as well. The Canadian Agency for Drugs and Technologies in Health (2016) found that breastfeeding ease improved via both the simple release and Z-plasty procedures, in particular there was better latching and jaw locking. This review also noted that Z-plasty had greater parent satisfaction compared to the simple release.

INTRODUCTION TO OROFACIAL MYOFUNCTIONAL THERAPY

As I mentioned earlier, muscular rehabilitation and training is a critical piece to frenectomy success. Orofacial myofunctional therapy (OMT) is a non-invasive behavioral modification program that uses principles of neuromuscular re-education to re-establish proper oral rest posture, more efficient chewing and normalized swallowing, sleep quality, nasal breathing, and reduce clenching/grinding, neck, shoulder, facial tension or pain, as well as snoring (Zaghi, 2019). Huang et al. (2015) additionally note that a frenectomy alone is often not sufficient to resolve all abnormal breathing patterns when sleep-disordered breathing is present; myofunctional therapy may be needed to support the development of nasal breathing post-surgery. In addition, Saccomanno et al. (2012) shared similar sentiments about myofunctional therapy in relationship to orthodontic treatment. They stated that orthodontic therapy, when in the presence of parafunctional orofacial habits, is not enough to resolve orthodontic issues and must be combined with myofunctional treatment. It truly is a team effort to address the tongue and its consequences on growth and development in all age groups.

OMT offers improvement in tongue elevation strength, posture at rest and positioning during swallowing (Van Dyck et al., 2015). OMT treatment also has a positive impact on remediating symptoms such as an anterior open bite, which also often go hand in hand with tongue ties and/or tongue thrust habits, mouth breathing, thumb sucking, or dental eruption disturbances, as well as malocclusions. However, Proffit (1978), like Mew concluded similarly that the resting tongue position was more of a contributing factor in terms of causing an open bite. A skilled OMT therapist will provide the necessary training to enable a patient to lift the body of the tongue so that it gently rests on the roof of the mouth away from the teeth, which is its normal resting position. Van Dyck et al. (2015) and Korbmach et al. (2004) offer additional objectives that include strengthening the orofacial muscles for mouth closure, establishing nasal breathing and learning a physiological swallowing pattern.

Habit breaker bite closure

Challenges to OMT include limited office space, lack of providers, time/commitment required for the therapy, and lack of belief that there is sufficient scientific evidence, to name a few (Van Dyck et al. (2015). I’ve personally found it challenging to convince my own patients to look into OMT. There is limited research in relationship to when to start OMT, as well (i.e. before or after orthodontic and/or frenectomy procedures) or if there is an ideal age to start. At minimum, a child would need to be old enough to understand the instructions and purpose of the treatment, as well as perceive an awareness of the tongue. Motivation and compliance of both children and parents is a key component. Van Dyck et al. (2015) cite that children experience an increase in oral awareness and tongue positioning. Orthodontists commonly address tongue motor or postural dysfunction with devices such as tongue spurs, cribs, shields or other functional appliances. Many of these will assist in passive bite closure and allow for unobstructed incisor eruption; however, the authors cite that there is little known about soft tissue adaptation after discontinuation of treatment. Thus long-term stability is unknown. Therefore, if an appliance is removed and if the cause of the tongue pattern is not addressed, relapse and habit return are to be expected, unfortunately. Some postulate that these appliances stimulate a biofeedback mechanism that might ‘inform’ a patient of a faulty tongue position, which enables habit correction. A combination of OMT and orthodontics may offer the best possible treatment outcomes, consequently.

CONCLUSION:

The tongue is a vital muscle that influences craniofacial growth and development from infancy and onwards. Tongue ties are a relatively common anomaly and may negatively influence jaw development as well as present challenges in breastfeeding, physiological swallowing patterns and speech expression. A joint intervention between tongue tie resection, orthodontic/orthopedic treatments and orofacial myofunctional therapy is an essential triad to offer both long-term stability and a foundation of health.

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