Posterior Open Bite

A posterior open bite occurs when only the front teeth make contact upon biting down, leaving the back teeth (posterior teeth) not touching at all.

Causes Linked to Aligner Treatment

The most common cause of a posterior open bite during aligner treatment is premature contact between the lower and upper front teeth. This can force the jaw backward, resulting in strong contact at the front and little to none at the back. Another less common theory suggests that the approximate 1.5 mm gap created by the thickness of the aligners may lead the back teeth to intrude under biting forces, causing a posterior open bite. However, this hypothesis is less convincing as biting forces are only significant for a small portion of the day, unless the patient engages in frequent heavy grinding (bruxism). There is also a lack of evidence showing molar intrusion caused by aligners without specific programming for it.

Solutions for Managing Posterior Open Bite with Clear Aligners

Monitoring the development of a posterior open bite during orthodontic treatment with clear aligners is crucial. It's advisable to check for signs of this issue before using the last few aligners so that any necessary adjustments can be made swiftly.

If heavy, premature anterior contact is identified as the cause:

• Request a Revision: Adjustments might include intruding and proclinating the upper incisors, and intruding and lingualizing the lower incisors to alleviate the premature contact and allow the posterior teeth to meet.
• Re-impress or Re-scan: Accurately capture the current state of the posterior open bite to guide the technician in how to adjust the front teeth appropriately.

If the issue might be due to suspected molar intrusion without significant anterior contact:

• Modify the Aligners: Remove the aligner material from over the "intruded" molars by cutting the aligner just beyond the second bicuspids. This may help the teeth to re-settle into proper occlusion.
• Regular Monitoring: Ensure there is no excessive eruption of the opposing teeth.
• Use of Orthodontic Accessories: Applying buttons or brackets on the buccal sides of the affected teeth and using elastic bands can help close the open bite. This method is sometimes referred to as using an "elastic box" or "triangle."

In all scenarios, close observation and timely intervention are key to correcting a posterior open bite effectively during aligner treatment.