New grid device helps orthodontists accurately place and guide the newly approved mini-orthoscrews

Jul 21 2004

The newly Food and Drug Administration - approved orthoscrew - so tiny it is dwarfed by a fingertip - is difficult to place between the narrow spaces of teeth roots and bone.

Young Jin Jeon, a visiting assistant professor at the Case Western Reserve University School of Dental Medicine and an orthodontist from Pusan National University in Korea, developed a new grid device during his yearlong residency at Case that will help orthodontists accurately place and guide the newly approved mini-orthoscrews without damaging the teeth.

Called the JJ Aligner, which looks like a tiny half-inch plastic square of graph paper, is attached by the orthodontist to patient's jaw and then x-rayed to show where teeth roots and bone are in relations to the grid. After the patient's gum tissue has been numbed (much like that for a dental filling), the orthodontist will implant the screw using the combination of the x-ray and the grid as a guide. Jeon has a patent pending in Korea on the device. When he returns to Korea at the end of June, he plans to form a company to manufacture the grids for the eventual use in Korea and the United States.

Mark Hans, chair of Case's department of orthodontics at the dental school, praised the new grid device, saying that the device will allow orthodontists, who are interested in using the orthoscrews to accurately place them between the teeth without damaging the roots of the teeth.

Reducing placement errors which might damage teeth and bones motivated Jeon to design the grid. "Without experience, it is difficult to learn where to put the screws by just looking at an x-ray and the patient's gums," said Jeon.

Since 1996, Korea has led the development of medical screws in dentistry. The screws are a variation of the surgical steel pins used to piece broken bones together and have a head much like the screws used to anchor wood to a wall.

These screws have been used in Korea for some of the most complex orthodontic cases and can hold wires where teeth may be missing or where the movement of teeth can only take place by using head gear (appliance that has to worn at night that uses the head or back of the neck to assist the orthodontist in moving the teeth).

In the United States, oral surgeons have used a type of dental screw as a post for teeth implants, but those screws permanently remain in place as bone grows around the screw over a six-month period as the anchor to hold the implanted tooth. The mini-screws for orthodontics are designed to be removable and taken out after the teeth have been moved their way into the correct position.

The Case dental school's orthodontic clinic is among the first in the country to use the new screw technology, said Hans. It currently is being used on one patient.

Hans said he believes the technology will become popular and, in some difficult orthodontic cases, might even eliminate the need for upper jaw surgery.

"The orthoscrews are not used for routine orthodontic cases," added Hans, but only in very complicated ones such as cleft palates or other jaw deformities that require unusual tooth movement and where the screws can replace the head as the anchor. Jeon, who has used the technology for a number of years on his patients in Korea, has seen a reduction in the number of jaw surgeries where the screws can anchor wires in ways that can push or pull teeth in unusual directions.