Abstract
From many years of experience of using the mushroom arch-wire, a number of problems were encountered, such as detailing requiring many complicated bends or the difficulties in arch co-ordination between the upper and lower. Because of these problems, in 1996 the author began researching a lingual multi-bracket system using a plain arch-wire that did not require bending.
3 main points which are indispensable for the straight wire method are 1) a gingival offset. 2) the ideal arch wire must pass as close as possible to the lingual surface of the central incisors, the first premolars and the first molars. 3) The bracket slot width must be designed to be as small as possible. For the above reasons, new passive self-ligation bracket with a square slot was designed.
Considering both the possible degree of play between the wire and the bracket slot in the leveling stage and the stiffness of wire needed to carry out retraction without the bowing effect during space closing, it was decided to use a .018×.018 slot size.The thickness of the bracket on the front teeth which has been designed with a maximum of 1.7 mm is very thin.The slot width on the upper anterior teeth is 1.5 mm and on the lower anterior teeth is 1.2 mm. The result is that the inter-bracket distance is increased and so treatment with lighter force becomes possible.
The quality of the treatment depends on whether or not sufficiently close attention has been paid to the preparation of treatment such as an accurate diagnosis, a precise impression taken, an accurate set-up model and accurate bonding positioning of the brackets. Then favorable treatment without wire bend can be achieved.
