Two or 4 Extraction?
Four extraction ortho is presented to the patient's mother. She does not agree lower bicuspid extraction. Her reasoning is that the lower teeth are not so crowded (Fig.2). Closer look shows that the lower incisors are somewhat lingually inclined. The patient is scared when the upper bicuspids are extracted (Fig.1). The final result will be most likely canine Class I and molar Class II (1,2).
I have done many. But the decision lies in lower arch crowding. Zero to 1mm only. Any crowding will need IPR.
When the patient returns, you will be surprised to find the alignment (Fig.3). The UR 3 has started distal drifting (Fig.4,6), while the UL 3 needs distal retraction (Fig.5), either power chain (Fig.7) or closed coil spring. Take photos either prior to change of wires (if oral hygiene is not bad) or after (Fig.3-7, 16x16 ss wires, 4.5 months post bracketing). Check overjet before retraction. In fact, the overjet allows to retract the upper anteriors.
Three weeks later, UL3 and 5 have approximated each other (Fig.8). The long axis of UR3 (Fig.9 white line) is off. After changing to 16x22 wires, power chain x2 is placed between UL 3 and 5, while power chain x3 (without twist) is between UR 3 and 5. The purpose of the latter is to change the axis of UR3. The patient is coming back in 3 weeks. Use a unilateral child cheek retractor for photography.
What should be done when U3 enters the space between L3,4?
Eighteen months post banding, anterior over bite and over jet and posterior interdigitation are within normal limit except UR5 rotation. For correction of the latter, two lingual buttons are placed with power chain (Fig.10). The lingual button at UR3 dislodges in a few days. It is placed at UR2; Fig.11 is taken 1 month post placement.
Return to Professionals
Ext or Not
Before & After
Xin Wei, DDS, PhD, MS 1st edition 03/13/2015, last revision 04/16/2017