A Compare Of The Three Dimensional Change In The Upper Teeth When Rocking Chair Archwire Was Used

Objective: To observe the three dimensional change tendency of upper arch when rocking chair archwire was used in patients of Angle Class I or Class II with I or II degree deep overbite. The objective include the changes of the curve length and width of dental arch, the changes of the location of the upper labial teeth and the anchorage teeth, and the differences between using the different brackets and fixed methods.Methods: Choose 40 patients, 22 boys and 18 girls, between 15 to 21 years old(17.4 on average), which were Angle Class I or Class II with I or II degree deep overbite. All the patients were divided into two groups according to the brackets. And each group was divided into the group of using laceback and cinch back and the group of not. After all the patients' overbite had been opened by using the typical swinging chair labial arch, they were taken standardized lateral cephalograms and gypsum gnathodes. Some hard and soft tissues landmarks were selected and evaluated and use the laser scan and Imageware software to do the digital model analysis. All data were analyzed by SPSS 12.0 software to study the correlation of the changes between the groups.Results: There were some significant changes in upper teeth and arch when rocking chair archwire was used to leveling the upper curvilinear.(1) The incisors were depressed while the canines changed little. The second bicuspids were elevated. And the mesio-buccocusp of the first molar didn't move at the same time the apo-buccocusp was depressed. (2) In the groups using laceback and cinch back, incisiors made labial movement, canines made the aomovement, while the premolars and the molars changed little.(3) Changes of the arch width: There was no significant change in arch length and width when rocking chair archwire was used. All the width between molars increased.(4) Changes of arch curve length: the length was increased in all the group. The changes of the group using laceback and cince back was less, and the compare has statistical significance.(5) Compare pretreatment and post-treatment, there was no obvious correlation at the S point, N point, A point or their angles. While the location and angle of UI point changed obviously, and it has statistical significance.(6) There were no obvious changes in the survey marks between the two group of different brackets.CONCLUDE: Rocking chair archwire was useful to the patients of Angle Class I or Class II with I or II degree deep overbite. And it will make the teeth change in the three dimensional. When leveling the upper curvilinear and opening the overbite, the location and angle of UI point changed obviously while there was no obvious correlation at the S point, N point, A point or their angles. The location of the upper teeth changed: The incisors were depressed and had the tendency of labioclination; the canine show the tendency of apoclination; The second bicuspids were elevated. And the mesio-buccocusp of the first molar didn't move at the same time the apo-buccocusp was depressed. The morphous of the arch changed unobviously. The width between molars increased while the width between the canines and premolars changed little. The laceback and cinch back had some influence in the movement of the teeth using rocking chair archwire. Brackets effected little to the rocking chair archwire made in round wire for opening the overbite.