What you didn’t learn in dental school: Part 4 – correcting posterior cross-bites

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Children with compromised airways and mouth breathing problems frequently suffer from constriction of the maxillary arch, which can result in a unilateral or bilateral posterior cross-bite, constricted mandibular arch, retrognathic mandible, or a combination of all three.

What you need to know

It is absolutely critical that a constricted maxilla and a posterior cross-bite be corrected as early as possible (ideally, in the deciduous or mixed dentition stages) to retain facial asymmetry and bypass future TMJ problems. Although most posterior cross-bites appear to be unilateral, they are usually the result of a bilaterally underdeveloped maxilla with a shifting of the mandible to one side during closure. Allowing this shifting to continue, will impact the TMJ. Clinicians who treat and monitor the health of the TMJ routinely find that the proper development of the maxillary arch is one of the main keys to TMJ health. When the mandibular arch is constricted by an underdeveloped maxilla, crowding results. Speech problems may occur due to lack of adequate room for the tongue.

A constricted maxillary arch must be corrected with arch development appliances to ensure adequate space in the upper arch, increase nasal airway volume, and to ensure normal muscle function. Developing the maxilla to its proper size is often all that is needed to eliminate a posterior cross-bite, a facial asymmetry and/or a deviated skeletal midline.

What you need to do

1. Begin with the basics – panorex, cephalometric X-ray and analysis, diagnostic casts, and photographs. Taking the time to obtain these records will make all the difference, and alert you to possible additional treatment necessary for comprehensive care. Make an informed diagnosis. Take impressions. Select the ideal appliance. Note: Most appliances will need occlusal coverage to correct the cross-bite.
2. Check the completed appliance for fit, taking special care to adjust the occlusal bite plane so that there is equal contact throughout the posterior region. Premature contact can cause the patient to shift the bite abnormally. The mandible must also be free to move normally in anterior and lateral excursions without being restricted by any occlusal interferences. Be sure the patient eats with the appliance – only removing it for hygiene purposes.
3. Activate and evaluate. One week later, have the patient begin activating the expansion screw at a rate of one to two adjustments per week. After the second week, evaluate the patient (and proper adjustment) at one-month intervals.
4. Upon completion of treatment, maintain the correction. With minor adjustments, most appliances can then be worn as a retainer. When this is not the case, be sure to make a final retainer. It is essential to maintaining the correction for the next six to nine months.
5. Consider your options.Once correction is achieved, make a determination regarding the necessity for further treatment.

A critical concern

It is critical that clinicians understand the relationship between mouth breathing, airway problems and their detrimental impact on the size of the maxilla. Airway evaluation is essential. Detection of common airway problems must occur before application of any arch development appliances.

Functional and skeletal problems should be corrected – non-surgically – in mixed dentition, utilizing functional jaw orthopedic appliances prior to the eruption of the permanent teeth. When this is done, it usually constitutes phase one of a two-phase therapy.

Average fees for phase one therapy in the mixed dentition range from $1,000 to $3,000 per case. Your fee will vary based upon the complexity of the case and whether or not finishing will require full arch bracketing. Delaying treatment until permanent dentition (when surgery is often required) is, in most cases, not in the best interest of your patient.

Bottom line: starting just two patients per month can add more than $33,000 in gross production to your practice.

Note: For a more detailed, comprehensive discussion of posterior cross-bites and appropriate appliance therapy, consult "Principles of Appliance Therapy for Adults and Children" by Dr. Veis and John Christian, MBA, CDT (Section 7 - Cross-bites), or visit www.appliancetherapy.com.

Dr. Rob Veis is CEO of the Appliance Therapy Group® (ATG). Reach him through www.appliancetherapy.com or by calling (800) 423-3270.