Anterior crossbite is a condition that affects 4 to 5 percent of the world population, and between 9 and 11 percent of Mexicans. Roberto Ruiz Diaz, coordinator of the Orthodontics Spatiality at the Faculty of Dentristy (FD) of the National Autonomous University of Mexico (UNAM) and his team of orthodontists have created a reverse face mask able to correct this condition also known as Class III malocclusion. The team achieved this breakthrough by modifying a similar device designed in the 60s by Hickham at Baylor University in Texas, US.
In clinic practice, the researchers realized that traditional mask had adverse results in patients with excessive vertical development of the posterior facial height (hyperdivegent) that results in improper alignment of the bite, so they decided to design this innovative orthopedic mask, achieved through research and technological development.
Most of these devices have a front support and other for the chin, which are fastened by elastic bands that run from the forehead to the mouth. Due to gravity, masks tend to move downward. This means that if one pulls the jaw from the point of force application, the anterior part rises and the posterior descends; in other words, the jaw rotates clockwise, increasing the open bite.
“Instead, as we change the pulling direction and the mask concept to more easily fit the patient’s face, our reverse face mask has a skull-chin support that prevents it from opening or increasing the bite and helps to uncross it. All masks work in sagittal direction, but ours control better the adverse effects occurring with others,” said Ruiz Diaz.
Currently, the Department of Orthodontics at the FD’s Division of Graduate Studies treats 80 percent of patients with upper maxillary retrusion, a variant of Class III malocclusion, with this reverse orthopedic facial mask.
We use this mask on those who require this treatment, to help their maxillary grow or to have a sagittal displacement towards the front, and in this way correct the crossbite, or what is the same uncross it and avoid it to open, said the specialist.
Most patients have positive changes – the bite gets uncrossed– during the first four months. The treatment lasts between 9 and 10 months; once completed, the mask removed.
How effective is this treatment? Ruiz Diaz answered: If only exists upper maxillary retrusion the prognosis is good; but if this is coupled with mandible problem there is a possibility that it returns to its original position 20 or 30 percent of cases. Patients with this problem should be treated with other devices for a long-term, to control the growth of the mandible.
The mask is dynamic, allowing that the mouth to open and close properly, sleeping on the side and almost on stomach. Furthermore, as children only need to use it when they are not at school and in rest hours, avoids that patients could be bullied.
It is also personalized, since is done in the dental chair, taking into account the characteristics of each patient. If commercialized, it will have a standard size, with some variations to adapt to each individual.
The specialist and his colleagues have made several prototypes reverse facial mask. The fourth prototype is already in the process of being patented, since a company is interested in its development and marketing.
Ruiz Diaz and colleagues will conduct a final comparative study to increase further evidence on the reliability of the device for correcting malocclusion class III. “Our goal is to evaluate its vertical control, compared to conventional masks.”
Before this treatment, people with this problem could remain that way, or when they grew up could receive a combined orthodontic treatment and surgery to correct these disharmonies or skeletal discrepancies.
“The reverse face mask prevents a child with Class III malocclusion get to the operating room in adulthood for correction. Similarly, in severe cases, can it help to reduce this skeletal discrepancy, so that the surgery could be less invasive,” he said.
Malocclusion refers to any degree of irregular contact of the teeth of the maxilla with the mandible. There are malocclusion class I, II and III (anterior inverse, or crossbite). In Class III malocclusions, mandible is relatively anterior to the maxilla, having some of the following characteristics: upper jaw retrusion, lower jaw protrusion, vertical maxillary deficiency, mandibular displacement to the front (pseudo-Class III malocclusion), and upper jaw retrusion with lower jaw protrusion — a combination of the first two.
Therefore, each patient must be treated differently. If the maxilla is inward, it must be treated orthopedically, i.e. it remains unchanged without moving the teeth.
Source: DGCS UNAM
