What Is Lip Incompetence?

Lip incompetence, also known as mentalis strain, refers to a condition characterized by an inability to easily hold the lips together while at rest. Other common features of lip incompetence include protruding lips, and strain in the lower facial region when you try to seal your lips. Many people with this condition also present with an elongated face, short upper lip, and dimpling of the chin. The severity of mentalis strain can vary widely. Although it may result in exposed front teeth, lip incompetence is not the same as having buck teeth. A famous example of lip incompetence is demonstrated by the character Napoleon Dynamite, from the 2004 film of the same name. 

You should schedule a consultation with an orthodontist if you suspect that you may be affected by lip incompetence. The condition is fairly simple to diagnose, and it is important that it is addressed sooner rather than later. This condition may be caused by any of a number of underlying issues — dental and otherwise — but regardless of the cause, it often results in serious side effects concerning the teeth and jaws. In fact, issues relating to your oral health may also negatively affect your overall health.

What Causes Mentalis Strain?

As stated, there are many possible causes of lip incompetence, including:

  • Allergies: Chronic allergic rhinitis is a very common cause of lip incompetence. This condition can obstruct your airway, leading to chronic mouth breathing, and eventual mentalis strain.
  • Deviated Septum: A deviated septum is an issue characterized by a misalignment of the bone and cartilage that separates your nasal cavities. You can be born with a deviated septum, or you may develop one as the result of an injury. This condition often results in reduced airflow, which again can lead to chronic mouth breathing and eventual mentalis strain.
  • Tongue Thrusting: Tongue thrusting is a tendency to push the tongue between the upper and lower teeth when swallowing. Lip incompetence and a tongue-thrusting habit commonly correlate. Either can cause or contribute to the other, but they can also both be caused by a separate underlying issue. 
  • Craniofacial Anomalies: This is another chicken-or-the-egg scenario. Lip incompetence can cause craniofacial anomalies, but can also be caused by craniofacial anomalies. “Craniofacial anomaly” refers to any misformation of the face and/or head, for which there are many possible underlying causes. Mandibular (jaw) anomalies may be especially likely to result in mentalis strain.
  • Weak Muscle Tone: Weak muscle tone in the lips or jaw may make it difficult for you to close your lips easily.
  • Digit-sucking: This habit mimics the posture of lip incompetence, and the posture itself may become habitual.
  • Enlarged Tonsils or Adenoids: Enlarged tonsils or adenoids can obstruct your airway, and therefore may cause a habit of open-mouthed breathing that may, in turn, result in mentalis strain.
  • Sleep Disorders: Sleep disorders involving airway obstruction may result in habitual open-mouthed posture. 

Effects of Mentalis Strain

Because cases of lip incompetence vary widely in terms of severity, and can be caused by a range of underlying issues, there are also many possible effects that may result from the condition, including:

  • Aesthetic Concerns: Lip incompetence can cause a wide range of craniofacial anomalies, such as “Long-Face Syndrome,” gummy smile, dimpled chin, disproportionate profile, asymmetry, etc. This may result in issues relating to self-confidence. 
  • Jaw Misalignment: Lip incompetence causes you to hold your mouth in an unnatural posture, which, in turn, can cause or worsen jaw misalignment.
  • Tooth Eruption: The jaw misalignment that may be caused by lip incompetence can also cause issues relating to tooth eruption. 
  • Breathing Obstruction: Misalignment of the jaw and muscle tone issues resulting from lip incompetence can also result in airway obstruction.
  • Sleep Apnea: Airway obstruction resulting from lip incompetence can cause sleep apnea. Sleep apnea, in turn, may cause a wide range of issues, including fatigue and heart disease. 
  • Issues With Jaw Joints: Lip incompetence commonly results in unusual resting positions of the jaw. This may cause damage to the jaw joints. 
  • Tongue Thrusting: Unusual resting positions of the mouth caused by lip incompetence may result in tongue thrusting.
  • Swallowing Issues: Poor resting position of the jaw, diminished muscle tone, and tongue thrusting caused by lip incompetence can result in issues related to swallowing.

Mentalis Strain Treatment

It is possible for children to outgrow this condition, but in the case of adulthood mentalis strain, additional measures will need to be taken. Additionally, it is relatively common for children to have a resting open-mouth posture without having diagnosable mentalis strain. However, even in childhood cases, it will be prudent to identify the underlying cause to assess whether the condition is likely to self-correct or not. 

Treatment for lip incompetence will depend on several factors, such as the severity of the condition, and the underlying causes. However, there are several common treatment options, such as:

  • Orofacial Myofunctional Therapy: This is a form of physical therapy focusing on the face. It involves simple exercises that are geared toward strengthening the muscles and resetting muscle memory. The exercises will be chosen by your doctor based on the issues being addressed.
  • Addressing Underlying Issues: If there is an underlying issue causing your lip incompetence, that will need to be addressed first and foremost. This may mean anything from getting a prescription for an antihistamine to breaking a thumb-sucking habit to realigning your jaw. 
  • Orthodontic Hardware: Many different issues relating to jaw alignment may cause or exacerbate lip incompetence. Hardware that your local orthodontist may recommend to rectify the problem may include palatal expanders, braces, Invisalign, and retainers.
  • Surgery: In some cases, such as those caused by enlarged tonsils or a severely misaligned jaw, surgery may be required to rectify the problem. 
  • Mouth Tape: In some cases, mouth tape may be prescribed as a short-term solution pending a more sophisticated treatment plan. This is meant to help create new muscle memory regarding mouth posture. This option should only be pursued under direction from a medical professional. 

Your medical professional may use one or more of the above treatment options. Treatment plans for lip incompetence are also often multidisciplinary affairs that require the collaboration of several medical professionals, which may include orthodontists, allergists, neurologists, ENTs, nutritionists, and more.