Have you noticed your child often resting with their mouth slightly open — lips apart even when they’re not talking or eating? It might look minor, but that open mouth posture could be quietly reshaping their face. When lips don’t close naturally at rest, and the mouth hangs open frequently, it changes how the upper jaw and surrounding bones grow. Over time, this can lead to narrower jaws, higher palates, crowded teeth, and a longer vertical face pattern.

The Problem: Lips Apart = Jaws Under Challenged

A child’s resting lip seal matters more than many realize. When the lips stay gently closed, the muscles around the mouth (including the orbicularis oris) help guide the upper jaw’s shape and width. But when lips stay apart, the oral posture shifts: the tongue may rest low, the mouth may open slightly, and the upper jaw receives less outward and upward stimulus. The result? A jaw that develops narrower than it should, with less room for all the teeth and a higher potential for crowding.

What the Research Shows

In the study by Drevenšek et al. (The Influence of Incompetent Lip Seal on the Growth and Development of Craniofacial Complex, Slovenian Journal of Orthodontics, 2006;13(2)), 84 children were evaluated for lip competence. Those with open mouth posture showed significantly greater lower facial height, higher palates, and narrower jaws — all indicators of vertical facial growth and dental crowding.

Full text available here: https://www.hrcak.srce.hr/file/8342

In plain language: children who struggle to keep their lips naturally closed are more likely to develop narrower jaws and faces that grow more vertically.

Why This Matters for Growing Faces

Narrow jaws don’t just mean less room for teeth. They also affect breathing, tongue posture, and facial balance. A narrower upper jaw often means a smaller dental arch, more crowding, and higher risk of orthodontic issues. The vertical growth pattern associated with lip incompetence can also lead to facial proportions that appear longer and less balanced. Early habits matter because structural growth is happening — fast. When posture cues (like lip seal) are off, the bone adapts around them.

What You Can Do: Build Lip Seal and a Balanced Jaw

1. Encourage Lips Together At Rest

Help your child practice light lip closure during daily activities: while breathing quietly, reading a book, or watching TV. Simply reminding: “lips closed, tongue up, breathe through your nose” can go a long way.

2. Use Structured Tools that Reinforce Lip & Jaw Function

This is where Blossom Myofunctional Gum steps in. It gives children a fun, consistent tool to use daily — one that encourages lips to stay closed during chewing and supports proper oral posture. When paired with our guided instruction and chewing exercises, it strengthens the muscles around the lips and helps establish a natural lip seal habit — the kind of habit research shows supports wider jaws and healthier tooth alignment.

The Takeaway

Here’s the bottom line: lip posture isn’t just about looks or habits. It’s a silent growth influencer. If your child’s lips rest apart often, it could be a sign that the jaw is on the wrong developmental path — one toward narrow arches and crowded teeth. By reinforcing lip seal and using tools to support proper chewing and posture, you can help guide their growth toward a wider, stronger, more balanced facial structure.

Jordon Smith, DDS
“The more you know, the better they grow.”