Imagine a child sitting calmly in an examination chair, with their mouth slightly open even when they are not speaking or chewing. To some parents, this may appear completely normal. However, for drg. Anrizandy Narwidina, MDSc, Sp.KGA, PhD, this condition is a clinical sign that deserves prompt attention.
The condition is known as lip incompetence (LI), defined as the inability of the upper and lower lips to achieve natural closure at rest. LI is not merely a habit of keeping the mouth open. It is an anatomical and functional condition that can have far-reaching effects on dental development, jaw growth, and even a child's sleep quality.
More Than Just an Open Mouth
The prevalence is not insignificant. LI affects approximately 30.7% of children aged 3 to 12 years, and the prevalence tends to increase with age. A study published by drg. Anrizandy and colleagues from the Department of Pediatric Dentistry, Faculty of Dentistry, UGM, in the Journal of International Dental and Medical Research (2024) reported an overall prevalence of approximately 35.72%.
The causes are diverse, ranging from nasopharyngeal narrowing that obstructs the upper airway and maxillary protrusion that makes lip closure difficult to secondary conditions such as a deviated nasal septum, chronic sinusitis, or enlarged palatine tonsils. When a child continually breathes through the mouth, the effects can be widespread. The dental arch may become narrower, the upper incisors may tend to tilt forward, and maxillary arch development may even become significantly restricted.
Less commonly recognized is the role of the orbicularis oris, the circular muscle surrounding the mouth that functions like a sphincter. This muscle can weaken due to insufficient lip-closure activity. Weakness of this muscle can affect chewing, swallowing, and speech, and may also contribute to drooling and articulation difficulties.
Three Appliances, One Goal
This literature review examined 401 articles from PubMed and manual searches, covering publications from 1980 to 2023. Of these hundreds of articles, seven studies demonstrated statistically significant results (p < 0.001) for three types of prefabricated orofacial myofunctional appliances (OMAs): the Oral Screen, Lip Trainer Patakara® (PATAKARA Co., Ltd., Tokyo, Japan), and Lipple Trainer® (SHOFU Inc., Japan).
All three devices operate according to similar principles but through different mechanisms. The Oral Screen is a shield-shaped device placed in the oral vestibule that trains the lip muscles both passively and actively. Patakara® applies direct resistance to the perioral muscles, particularly the orbicularis oris and buccinator muscles, stimulating contraction and strengthening. Meanwhile, Lipple Trainer® is designed for active pulling exercises from three positions: the center of the lips, the left corner, and the right corner.
The average treatment duration ranged from one to four months, following structured schedules. Patakara®, for example, was used for three minutes three times a day, five days a week, for three months. The result was a significant 4.1 N increase in Lip Closure Strength (LCS) after two months of therapy in children.
“OMA therapy may help improve oral coordination and stability, lip closure, and facial development. OMA may be a treatment option for improvement of LCS in children with lip incompetence.”
This was the conclusion reached by drg. Anrizandy Narwidina and colleagues in the paper, emphasizing that these devices are not merely orthodontic accessories but measurable therapeutic interventions.
The Numbers Speak, but Conditions Apply
The clinical findings were promising. Among children aged 7 to 9 years who used the Lipple Trainer® for three months, LCS increased from 7.9 N to 12.8 N. The 10- to 12-year-old group showed a similar increase, from 6.8 N to 11.4 N. The most significant improvement occurred during the first month of use. Another study found that Patakara® not only strengthened the lip muscles but also improved the Apnea-Hypopnea Index (AHI) and peripheral oxygen saturation (SpO₂) during sleep, suggesting improvements in children's breathing and sleep quality.
However, there is an important caveat. Not all patients responded equally well. Of seven patients who used an Oral Screen for 16 weeks in one study, only four showed significant improvement. Patients' systemic and general conditions, as well as their adherence to unsupervised home use, were difficult variables to control.
This is what makes OMA therapy different from conventional orthodontic treatment: its success depends heavily on the active cooperation of both children and parents. No matter how sophisticated a device may be, it will provide little benefit if it is not used consistently as instructed.
Early Detection, Timely Intervention
The paper emphasizes something that has often been overlooked: lip incompetence is not a condition that can simply be left to “wait until the child gets older.” The earlier it is detected and treated, the greater the opportunity for normal craniofacial development.
In clinical practice, LCS is measured as an important diagnostic parameter. Various assessment methods are available, ranging from visual examination and facial photography to electromyography and pressure-distribution sensors. However, awareness of the need to routinely assess lip-closure strength remains limited in many pediatric dental clinics.
The research by drg. Anrizandy Narwidina and colleagues serves as a reminder that behind a child's slightly open mouth lies a developing stomatognathic system that may need guidance in the right direction. Sometimes, the necessary intervention may be much simpler than expected.
Authors: Nanda Ayu, drg. Achmad Zam Zam Aghasy, M.Kes.
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