Comparison of the force levels among labial and lingual self-ligating and conventional brackets in simulated misaligned teeth.
OBJECTIVE
The aim of this study was to evaluate force levels exerted by levelling arch wires with labial and lingual conventional and self-ligating brackets.


METHODS
The tested orthodontic brackets were of the 0.022-in slot size for labial and 0.018-in for lingual brackets and were as follows: 1. Labial brackets: (i) conventional bracket (GAC-Twin, Dentsply), (ii) passive self-ligating (SL) brackets (Damon-Q®, ORMCO; Ortho classic H4™, Orthoclassic; FLI®SL, Rocky Mountain Orthodontics) and (iii) active SL brackets (GAC In-Ovation®C, DENTSPLY and SPEED™, Strite). 2. Lingual brackets: (i) conventional brackets (Incognito, 3M and Joy™, Adenta); (ii) passive SL bracket (GAC In-Ovation®LM™, Dentsply and (iii) active SL bracket (Evolution SLT, Adenta). Thermalloy-NiTi 0.013-in and 0.014-in arch wires (Rocky Mountain Orthodontics) were used with all brackets. The simulated malocclusion represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis).


RESULTS
Lingual bracket systems showed higher force levels (2.4 ± 0.2 to 3.8 ± 0.2 N) compared to labial bracket systems (from 1.1 ± 0.1 to 2.2 ± 0.4 N). However, the differences between SL and conventional bracket systems were minor and not consistent (labial brackets: 1.2 ± 0.1 N for the GAC Twin and 1.1 ± 0.1 to 1.6 ± 0.1 N for the SL brackets with 0.013-in thermalloy; lingual brackets: 2.5 ± 0.2 to 3.5 ± 0.1 N for the conventional and 2.7 ± 0.3 to 3.4 ± 0.1 N for the SL brackets with 0.013-in Thermalloy).


CONCLUSIONS
This is an in vitro study with different slot sizes in the labial and lingual bracket systems, results should be interpreted with caution.


CONCLUSIONS
Lingual bracket systems showed higher forces compared to labial bracket systems that might be of clinical concern. We recommend highly flexible nickel titanium arch wires lower than 0.013-in for the initial levelling and alignment especially with lingual appliances.
Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
Ahmad
A
Alobeid
Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.|Division of Orthodontics, School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Tarek
T
El-Bialy
Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
Said
S
Khawatmi
Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
Cornelius
C
Dirk
Orthodontic Department, School of Dentistry, University of Bonn, Bonn, Germany.
Andreas
A
Jäger
Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
Christoph
C
Bourauel
D003722:Dental Alloys; D006801:Humans; D007180:Incisor / Q000473:pathology; D008310:Malocclusion / Q000473:pathology / Q000628:therapy*; D009532:Nickel; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014025:Titanium; D014087:Tooth Movement Techniques / Q000295:instrumentation*
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium