3D Imaging for Better Diagnosis and Treatment of Pediatric Airway and TMD
by Robert Kaspers, DDS, MS
Proper breathing is essential to a child’s health, development, and educa- tional success. Early detection and correction of airway problems by health professionals, including orthodontists, can be integral to optimizing this fundamental physiology; and airway evaluation is an important part of the pro- cess. Comprehensive airway screening and subsequent treatment with the help of cone beam 3D imaging during childhood can help avert temporomandibular disorders and sleep-disordered breathing related issues in adulthood.
In my practice, evaluation of patients as young as six years old includes airway screening. Each patient receives a “low dose” CBCT scan to help diagnose common structural problems which would go unde- tected with conventional screening proce- dures. At this stage of development, skeletal problems can still be corrected with appli- ances whereas waiting until adulthood may necessitate orthognathic surgery to obtain the same results.
Airway and TMD screening are inter-re- lated. Research conducted in my practice has shown that almost 75 percent of pa- tients have a deficient lower jaw. As part of the research, I take all CBCT scans with the patient biting in maximum intercuspation. In this way, I acquire an image that allows me to evaluate how the patient’s occlusion affects their condylar position (See Figure
#1). Our compiled data shows that three out of four patients are indeed biting forward to get to maximum intercuspation. If the patient is holding their lower jaw forward during awake hours, the tongue may interfere with the airway during sleep.
i-CAT™ Tx STUDIO™ software provides helpful features for gathering clinical infor- mation as well as patient education. One such feature is the ability to take a fast, low- dose scan that gives me essential data for my particular evaluations. Another, the Airway Tool, provides color coding of the volume of a patient’s airway. Since the airway is diffi- cult for patients and parents to visualize, this color-coding aspect of the software can help to better educate them. It is easier to under- stand that when the scan shows the airway color-coded in red or black for various levels of constriction (See Figure #2), and white or blue for a more open airway (See Figure #3). In the past, if the patient was biting for- ward, orthodontists would have retracted the upper teeth to match up with the deficient lower jaw, but that type of treatment does not treat skeletal issues or help open the airway.
Now, I utilize a Herbst appliance to stimulate growth of the mandible which helps improve both airway and skeletal asymmetries, and once again, 3D imaging helps to create more precision. By analyzing cone beam scans over the past fou r years, I found that grow- ing patients who utilize the Herbst appliance average about 3-4 mm of additional growth of the mandible over the course of 12 to 18 months. This additional growth of the mandi- ble helps open up the patient’s airway.
With my CBCT scans and software, I am able to titrate the Herbst appliance properly by analyzing the condylar position. By achieving an accurate 3-4 mm stretch of the mandibular muscles, I can “repeatedly” obtain the necessary mandible growth. Before 3D imaging, I was like every other orthodontist receiving mixed results using the Herbst appliance. To the best of my ability, I would try to hand manipulate the patient’s lower jaw in an attempt to acquire the proper stretch of the mandibular muscles to stimulate mandibular growth. By analyzing a CBCT scan taken in maximum intercuspation, I know exactly which muscles are being activated to achieve a particular condylar position.
Several patients per year come to my office with Herbst appliances from orthodontists who do not use 3D imaging. The patients are in spasm because the orthodontist is not aware that the patient is already biting for-ward, and the Herbst appliance positions the jaw even further forward, throwing the lateral pterygoid into spasm and lockdown.
Sarah E. is a typical eleven-year-old girl with a retruded lower jaw and a constrict- ed airway (See Figure #4). Her initial CBCT scan showed her condylar position considerably forward on the eminence (See Figure#5), and yet her airway was still constricted as shown by utilizing the “airway tool” (See Figure #6). A second CBCT scan was taken one month later with Sarah biting in maxi-mum intercuspation, and you can see that the condylar position is less protruded (See Figure #7). By utilizing the Airway Tool and measuring the airway from the posterior nasal spine to the hyoid bone, you can see that Sarah’s airway decreased from 9.0 cubic centimeters to 7.2 cubic centimeters (See Figure#6 compared to Figure #8).
A Herbst appliance was placed to improve Sarah’s skeletal asymmetry and her airway. A CBCT scan was taken ten months later to assess when the Herbst appliance should be removed. You can see the significant improvement in her airway (17.0 cc) as well as her condylar position (See Figures #9 & #10).
Orthodontists may improve health, re- duce the possibility of development of future sleep apnea, and in some cases, possibly even save lives by being proactive with early treatment. Moving from 2D to cone beam imaging has considerably changed the way that I treatment plan for airway and TMD. Having that extra information and capacity for viewing the TMJ area and airway in 3D has changed my dreams for better patient care into reality