Duration and anchorage management of canine retraction with bodily versus tipping mechanics.
OBJECTIVE
To compare tipping mechanics (TM) and bodily mechanics (BM) with respect to duration, angulation, and anchorage loss during canine retraction.


METHODS
TM and BM brackets were bonded to the upper right and left canines, respectively, of 14 subjects requiring maxillary first premolar extractions. The upper canines were retracted with variable nickel titanium closed coil springs (F = 0.50 or 0.75 N) attached posteriorly to a Nance anchorage appliance through the first molars. Panoramic radiographs and dental casts were taken at five time points. Canine angulation was assessed with custom metallic jigs inserted into the vertical slots of the canine brackets prior to radiographic exposure.


RESULTS
The canine crown contacted the second premolar after 102.2 +/- 106 and 99.0 +/- 80.0 days, and achieved root uprighting in 72.0 +/- 31.3 and 37.2 +/- 42.7 additional days with the TM and BM groups, respectively. Only the uprighting stage differed significantly between the two mechanics (P < .05). During retraction, tooth angulation differed significantly (P < .001) between the TM (6 degrees ) and BM (-0.8 degrees ) groups. Anchorage loss, as assessed by mesial molar movement, was 1.2 +/- 0.3 mm and 1.4 +/- 0.5 mm for the TM and BM groups, respectively.


CONCLUSIONS
Bodily canine retraction occurred faster (38 days) than tipping due to a shorter duration of root uprighting. Anchorage loss (17%-20%) was similar for both retraction methods, ie, maximum anchorage could not be provided by the Nance appliance. Both TM and BM brackets had inadequate rotational control of the retracted canine.
Shpack
Nir
N
Department of Orthodontics, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. nshpack@post.tau.ac.il
Davidovitch
Moshe
M
Sarne
Ofer
O
Panayi
Narchos
N
Vardimon
Alexander D
AD
D001641:Bicuspid / Q000601:surgery; D001696:Biomechanical Phenomena; D003481:Cuspid / Q000473:pathology*; D003722:Dental Alloys; D001840:Dental Bonding; D006801:Humans; D008437:Maxilla; D003765:Models, Dental; D008963:Molar / Q000473:pathology; D009532:Nickel; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D011446:Prospective Studies; D011862:Radiography, Panoramic; D012399:Rotation; D012690:Serial Extraction; D013997:Time Factors; D014025:Titanium; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium