Letter to the Editor:
What is palatal expansion? If you search it on the internet, a palate expander – also called an orthodontic or palatal expander – is an oral device used to widen a narrow upper jaw. The inference is that the upper jaw just widens in a two-dimensional or along an axial plane. This is far from the truth. Nothing in the body is two-dimensional. Nothing in the body, including orthodontic treatment, is subject to Newtonian forces. A Newtonian force implies that force A on B will equal C. The body is three-dimensional and quantum. Force A on B can give anything W, X, Y, or Z. Applying a force to the crown of a tooth does not move it horizontally through the bone. At best, the tooth will rotate away from the force with the fulcrum somewhere in the bone. What is also misunderstood is that the palate is a single bone. In fact, it is two bones separated by a palatal suture. This means a palatal expander is more likely to rotate the two bones with the suture as a breakpoint. The significance of this observation is that the two bones do not necessarily move the same amount. We start with a lack of symmetry in the palate, and the goal is to create a wider and symmetrical dental arch. An orthodontist does this all the time. Reflect a moment, and you will see that since we are not necessarily symmetrical in our faces, an orthodontist is, in fact putting straight teeth in a crooked face. The implications are profound. The changes we make in the dental arch of the upper jaw will affect the position of the lower jaw, which in turn affects how our head sits on our cervical spine. Now we can see how the body functions in a quantum manner. The jaw and tongue position are the first elements of posture. Think of the jaw as being attached to the neck and head. It is a balancing act that can go wrong if the jaw is moved out of alignment.
In conclusion, I urge the Orthodontic community to be aware of cranial strains, craniofacial development, head posture and jaw alignment in their treatment protocol.
DDS, FPFA, FIADFE
Response from Dr. David Farkouh:
Thank you for your input regarding the expansion appliance. I would like to clarify how the rapid palatal expansion (RPE) appliance is used. RPE can only work in growing young patients, and we all agree that the maxilla is made of two parts where the mid-palatal suture is not fused, which allows the maxilla to expand. As the maxilla widens, the lingual cups of the maxillary molars can erupt, which can increase the lower face height, but that can be corrected using a bite block (or the usage of a bonded RPE).
So, to answer your concerns: First, please beware of not expanding where expansion is not necessary. Second, if your hypothesis is correct that “the jaw and tongue position are the first elements of posture”, you would agree that by expanding a narrow palate, we are allowing the tongue to find its ideal position, and that should improve the “balancing act” by putting the jaw into a better alignment. Finally, when we are expanding for the purposes of trying to allow the permanent teeth to come into an ideal position and thus save the lateral incisors from being lost, that should also allow a better tongue position (i.e., tongue sitting behind the teeth and resting towards the palate) and that by your theory should improve the jaw position. Thus, we have done no harm but benefit.
About the Editor
David R. Farkouh is a pediatric dentist in private practice in Toronto, Ontario. He is on staff at the Hospital for Sick Children in the Department of Dentistry in Toronto, Ontario. He is the Pediatric Dentistry Editor for Oral Health.