In tongue thrust with tongue-to-lip swallow, what oral condition is typically observed?

In cases of tongue thrust with tongue-to-lip swallow, one of the primary oral conditions observed is incompetent lips. This occurs because individuals with a tongue thrust tend to have difficulty sealing their lips when swallowing. The posture of the tongue against the lips can lead to an inability to maintain proper closure, resulting in the lips being unable to come together effectively. This condition can be a contributing factor to other dental and orthodontic issues, as the chronic tension on the muscles surrounding the mouth can influence the alignment of teeth and jaw position over time.

While other conditions such as malpositioned teeth, a high palatal arch, and an open bite can also be associated with tongue thrust patterns, they are not directly caused by the inability to properly close the lips. Instead, these dental issues may arise due to the physiological changes in the mouth that result from the tongue's improper resting position and habitual thrusting during swallowing or speaking. Hence, incompetent lips is the condition that closely and directly correlates with the observed behavior in tongue thrust scenarios.