An experimental evaluation of effects and side effects of asymmetric face-bows in the light of in vivo measurements of initial tooth movements.
By using a magnetic sensing system, the translational and rotational molar movements under the application of various asymmetric face-bows were measured two-dimensionally in human subjects to evaluate their primary effects and side effects. The asymmetric face-bow designs tested were three types of power arm face-bows, swivel offset face-bow, and internal hinge face-bow. Although all face-bow designs were considered to be effective in achieving asymmetric distalizations of the molars, they generated lateral displacements that may lead to an undesirable crossbite. The swivel offset face-bow may produce unexpected results and its fabrication is complicated. The internal hinge face-bow is remarkably effective for asymmetric molar distalizations. Unfortunately, it causes a strong crossbite tendency on the molar to be more distalized. Therefore the use of the power arm face-bow is thought to be relatively recommendable because it showed an acceptable asymmetric effect and is easily fabricated from a commercially available face-bow. It is concluded that all asymmetric face-bows generate lateral forces as side effects as long as the force delivery system with a combination of an asymmetric face-bow and a neck strap or head cap is applied. The current study suggests a method whereby the side effect of asymmetric face-bows can be eliminated.
Yoshida
N
N
Department of Orthodontics, School of Dentistry, Nagasaki University, Japan.
Jost-Brinkmann
P G
PG
Miethke
R R
RR
König
M
M
Yamada
Y
Y
D000328:Adult; D005069:Evaluation Studies as Topic; D005115:Extraoral Traction Appliances / Q000009:adverse effects* / Q000706:statistics & numerical data; D006801:Humans; D008280:Magnetics; D008437:Maxilla; D008963:Molar; D016382:Orthodontic Appliance Design / Q000009:adverse effects* / Q000706:statistics & numerical data; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000706:statistics & numerical data