Dr. Rob Veis

Problem: An anterior crossbite in the mixed dentition.

Solution: To create sufficient space and jump the crossbite with a simple removable appliance.

When there is insufficient space in the dental arch for the permanent lateral incisors to move labially during their emergence, these teeth will change their path of eruption and become palatally positioned in the crossbite.

Patients who have a simple anterior dental crossbite exhibit the following characteristics:

The anterior crossbite must be treated in the primary and mixed dentition. Allowing this malocclusion to continue into the permanent dentition without correction can result in labial displacement of the opposing incisor, gingival recession, occlusal trauma, abnormal chewing, abnormal growth and TMJ dysfunction.

Upper schwarz expansion appliance with posterior coverage and a finger spring.

A single tooth anterior crossbite.

Anterior crossbite corrected after 3 months.

The most common appliance used to correct this problem is a simple Anterior Crossbite expansion appliance with recurve springs. The typical design has an expansion screw for arch development a passive labial bow to control lip pressure and limit anterior movement, Adams clasps or C clasps for retention and a posterior bite plane when the anterior teeth are lingually locked behind the lower incisors.

Treatment Procedures:

1. Start by taking a set of accurate alginate impressions and pour them up in yellow stone. Air bubbles or holes on tooth surfaces are unacceptable as they can negatively effect the fit of the appliance. Wrap these casts carefully out of occlusion.
   
2. Provide a carefully taken construction bite that represents the exact vertical and AP position that you desire in the finished appliance. Wrap the bite separately.
   
3. Fill out the lab slip completely. Detailed instructions as to the type and placement of your clasps, springs and bite plane are essential.
   
4. Activation of the recurve spring should be done every four weeks by opening the spring approximately 2.0 mm. These springs often tend to ride up the lingual surface of the tooth. One method to prevent this from happening and keep a constant force on the tooth is to bond a small composite button on the lingual surface. This will allow you to engage the spring under the button preventing it from riding away from the tooth.
   
5. Retention of a removable appliance is often difficult in the primary dentition. To overcome this problem, simply bond a composite button on the buccal surface of the tooth being used for retention to create an undercut for the clasp.
   
6. Retention of the crossbite correction is usually required only if there is not a positive overbite after the crossbite has been jumped.