Arch development (widening) techniques
The technique of widening the dental arches (orthodontists call it expansion) was already in use a hundred years ago so that crowded teeth could be accommodated without any extractions. However, properly conducted scientific research has shown that indiscriminate use of this form of treatment leads to relapse in many cases with a return of crowding, although expansion can be very successful in carefully selected cases.
|Successful expansion treatment|
There are many types of functional appliances, mainly to treat underdeveloped lower jaws. Some are fixed to the teeth but most are removable by the patient for cleaning. They all work by holding the lower jaw in a forward position for 9 to 12 months.
Dr Kirschen and Dr Harris use 'Twinblock' functional appliances which are very effective at changing the way the teeth bite together by restraining the upper dental arch and advancing the lower dental arch. It is nearly always necessary to complete treatment with fixed braces to fine tune the bite and straightness of the teeth.
|Before and after Twinblock treatment|
The timing of treatment is an area of controversy. One school of thought is that the Twinblock phase should take place 'early', at age 7 to 9, with a two year interval before the fixed brace phase. However, an early start does not mean that treatment finishes earlier, but usually means a longer overall period of treatment at higher cost.
Dr Kirschen and Dr Harris prefert o begin treatment in the final year of the mixed dentition (when there is a mixture of primary and permanent teeth). This ensures that the two phases of treatment can take place one after the other, without pause. This shortens the overall duration of treatment, reduces costs and is preferred by patients.
Despite the above, early treatment can be appropriate when the upper front teeth protrude in such a way that the risk of accidental damage is increased or when the young patient is suffering from being teased.