[Simultaneous intrusion and retraction of the anterior teeth using a three-piece base arch].
OBJECTIVE
To evaluate the effects of the three-piece base arch on overbite correction of Class II malocclusion.


METHODS
20 patients with high angle, flared incisors were treated using a three-piece base arch appliance. The intrusion force of four upper incisors was adjusted to approximately 50 g. The line of force action was 2 mm distally to the resistant center(RC) and the retraction force was 20 g, the right and left posterior segments were joined by a palatal bar. Cephalograms were taken before treatment (T1) and six months after treatment (T2).


RESULTS
The upper molars moved mesially 0.60 +/- 0.35 mm and the distance of the vertical extrusion was 0.80 +/- 0.52 mm. The distances of the upper central incisor retraction and intrusion were -4.20 +/- 2.12 mm and 3.10 +/- 0.54 mm respectively. The RC of the central incisor retracted -4.12 +/- 1.96 mm and intruded 3.20 +/- 0.66 mm. The axial inclination of the upper incisor-palatal plane changed from 123.21 degrees +/- 4.26 degrees to 116.00 degrees +/- 3.96 degrees.


CONCLUSIONS
The three-piece segmented approach can effectively intrude and retract the upper anterior teeth for flared incisors and deep overbite.
Liu
D
D
Department of Orthodontics, Shandong Medical University.
Bai
D
D
Wang
C
C
Sun
W
W
Guo
J
J
Xi
R
R
D000293:Adolescent; D002648:Child; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007180:Incisor; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008963:Molar; D009971:Orthodontics, Corrective / Q000379:methods*; D014087:Tooth Movement Techniques