Orthodontic Tips June 2, 2014
Events seem to come in threes.
This month I saw two dual bite patients. I guess there is another one on the way.
A dual bite is a situation where maximum dental intercuspation (MI) is not the same tooth and jaw position as centric relation (CR).
The patient may be asymptomatic for many years while their jaw muscles and ligaments are young and flexible. However, at some point their jaw system can no longer compensate for this poor bite resulting in TMJ distress, bruxing habits or sleeping disorders.
This has been reported many times in the literature. Giffin K.M reported in Gen Dent. 2003 Jan-Feb;51(1):62-7 that “Effective management of this syndrome requires establishment of harmony between CR and MI.”
I discovered the dual bite after inserting TMJ splints for these patients. Neither one of these adults had braces before. Both of them complained that even though at night time they slept well with their splints, in the morning their bite was changed. It took about an hour for their bite to settle into their normal position. They wanted to know what was going on.
I explained to them that their normal bite was not the correct one to match the way the jaw is supposed to fit with the skull. When the splints were inserted, the jaw could return to the correct position because the teeth didn’t interfere. But when the splint came out the discrepancy was apparent.
The jaw settles by stretching the ligaments of the jaw joint to accommodate to the match between the upper and lower teeth.
If the discrepancy is small, an occlusal adjustment might be sufficient to allow a “long centric”. If the discrepancy is not small or is an open bite, orthodontic treatment is indicated.