Molar distalization with different pendulum appliances: in vitro registration of orthodontic forces and moments in the initial phase.
OBJECTIVE
Registration of the orthodontic forces and moments acting with different types of pendulum appliance for non-compliance upper molar distalization in an in vitro study.


METHODS
The purpose-designed test set-up comprised the following components: artificial maxilla with anchorage unit and two electrothermodynamic (ETD) molars, electronic measuring unit for temperature control and regulation, and a sensor unit with force-moment sensor, analog/digital converter and data readout unit. This set-up permitted virtually authentic simulation of in vivo conditions on the one hand and precise determination of the force systems on the other. The appliances investigated were the standard pendulum appliance with U-loop activation according to Hilgers and with uprighting activation according to Byloff, the M-pendulum with U-loop activation according to Scuzzo, and the Pendulum K with initial uprighting activation, toe-in bend and incorporated distal screw according to Kinzinger.


CONCLUSIONS
The effects shown by the standard pendulum appliance and the M-pendulum over a 3 mm simulated distalization increment were a marked decrease in the distally directed forces, and an increase in the intrusive and palatally directed forces as well as in the distoinclinatory, mesially inward, and palatally rotating moments. Activations in the U-loop region of the pendulum springs induced an increase in distally and buccally directed forces and in uprighting and buccally rotating moments as well as a marked rise in extrusive forces. Whereas the activation described by Hilgers led to mesially outward rotating moments, activation according to Scuzzo resulted in a further increase in the mesially inward rotating moments. In the measured standard pendulum appliances, uprighting activation at the end of the pendulum according to Byloff led to an increase in distally and buccally directed as well as in mildly intrusive forces, and to an increase in uprighting as well as in buccally and mesially outward rotating moments. With the Pendulum K according to Kinzinger, the initial toe-in bend and uprighting activation in the region of the end of the pendulum spring together with regular adjustment of the incorporated distal screw permitted virtually translatory molar distalization: constantly distalizing forces with slight intrusive, buccally directed, and rotating side effects.
Kinzinger
Gero
G
Department of Orthodontics, University of Aachen, Germany. GKinzinger@ukaachen.de
Syrée
Christian
C
Fritz
Ulrike
U
Diedrich
Peter
P
D003799:Dental Stress Analysis / Q000379:methods*; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar / Q000502:physiology*; D009967:Orthodontic Appliances; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation* / Q000379:methods; D019415:Torque; D016896:Treatment Outcome