The effect of buccal-lingual slot dimension size on third-order torque response.
The focus of the presented study was to investigate the effect of buccal-lingual (B-L) orthodontic bracket slot dimension on third-order torque mechanics.



Three types of orthodontic brackets and two archwire sizes were considered. Ortho Classic H4 (0.026″ B-L slot, passive), Ormco Damon Q (0.028″ B-L slot, passive), and In-Ovation R (0.028″ slot, active) brackets were tested using 0.017″ × 0.025″ and 0.019″ × 0.025″ beta-titanium archwires. An in vitro orthodontic torque simulator (OTS) was used to rotate archwires relative to a single bracket while recording forces and moments in three directions. For each bracket-archwire combination, a total of n = 47 samples were tested. Repeated measures analysis of variance between brackets was conducted for third-order torque values at 3° increments between 9° and 30° during loading and unloading for each archwire size.



Statistically significant differences between H4 and Q brackets were only found for 0.017″ × 0.025″ archwires during loading, and 0.019″ × 0.025″ archwires during unloading. Conversely, differences between H4 and R brackets were found for both archwires during loading and unloading phases. Finally, when using a 0.017″ × 0.025″ archwire the H4 brackets reached the 5 Nmm threshold before R and Q brackets; however, there was little difference found when using a 0.019″ × 0.025″ archwire.



The concept of using a smaller B-L bracket slot dimension in orthodontic treatment showed it may theoretically allow for more options, primarily using smaller archwires to correct third-order rotational misalignments. However, it is suspected that bracket material limitations and added loading on the door currently prevent this from being clinically applicable.
School of Dentistry, Faculty of Medicine and Dentistry and.
Dan L
DL
Romanyk
Department of Mechanical Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada.
Kenji
K
Au
School of Dentistry, Faculty of Medicine and Dentistry and.
Darren
D
Isfeld
School of Dentistry, Faculty of Medicine and Dentistry and.
Giseon
G
Heo
School of Dentistry, Faculty of Medicine and Dentistry and.
Michael P
MP
Major
School of Dentistry, Faculty of Medicine and Dentistry and.
Paul W
PW
Major
D003799:Dental Stress Analysis / Q000379:methods; D006801:Humans; D008422:Materials Testing / Q000379:methods; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel; D014025:Titanium; D019415:Torque
C023988:beta titanium; D013193:Stainless Steel; D014025:Titanium