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Dr. Heinz Weinsauer - Dr. Alfred Peter Muchitsch - Chapter 11
Pulling or Pushing Class II Mechanics?
"At first it may not seem that the difference between these two types of mechanics is particularly relevant, since it is clear that both aim at the correction of Class II situations. However, the effects are different and important.
Pulling intermaxillary Class II mechanics, such as elastics or closed superelastic coil springs, may lead to open bite situations due to the extrusion of teeth and an increasing force when opening the mouth. As extrusion happens much faster than intrusion, this is a common threat.
In contrast, pushing intermaxillary Class II mechanics have an intruding side effect on upper molars and lower anterior teeth. As mentioned above, this vertical effect (intrusion) is much smaller than the extrusion created by pulling appliances. At the same time, it must be realized that the greatest force levels in the pushing devices are achieved in the final stages of mouth closing and include therefore a significant horizontal component. Taking this one stage further, it is interesting to contrast the effect of the Jasper Jumper™
and the FD. Experiments and clinical evidence show clearly that the effect of the FD is similar to that of the Herbst appliance, whereas the Jasper Jumper develops its maximum force while the force vector is in a less optimal (more vertical) direction.
Using rigid constructions such as the Herbst appliance or the FD, an immediate decrease of force is observed when the patient moves the mandible forward or opens the mouth only slightly. Therefore the FD can be applied even in high angle Class II or in open bite cases (see Figs 11.20–11.36).
More than 2000 orthodontists are now using the FD because of its simple insertion and outstanding durability."
Pulling or Pushing Class II Mechanics?
"At first it may not seem that the difference between these two types of mechanics is particularly relevant, since it is clear that both aim at the correction of Class II situations. However, the effects are different and important.
Pulling intermaxillary Class II mechanics, such as elastics or closed superelastic coil springs, may lead to open bite situations due to the extrusion of teeth and an increasing force when opening the mouth. As extrusion happens much faster than intrusion, this is a common threat.
In contrast, pushing intermaxillary Class II mechanics have an intruding side effect on upper molars and lower anterior teeth. As mentioned above, this vertical effect (intrusion) is much smaller than the extrusion created by pulling appliances. At the same time, it must be realized that the greatest force levels in the pushing devices are achieved in the final stages of mouth closing and include therefore a significant horizontal component. Taking this one stage further, it is interesting to contrast the effect of the Jasper Jumper™
and the FD. Experiments and clinical evidence show clearly that the effect of the FD is similar to that of the Herbst appliance, whereas the Jasper Jumper develops its maximum force while the force vector is in a less optimal (more vertical) direction.
Using rigid constructions such as the Herbst appliance or the FD, an immediate decrease of force is observed when the patient moves the mandible forward or opens the mouth only slightly. Therefore the FD can be applied even in high angle Class II or in open bite cases (see Figs 11.20–11.36).
More than 2000 orthodontists are now using the FD because of its simple insertion and outstanding durability."
Appliance used in this study
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FLEX DEVELOPER™
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"Even after continuous use for many months there is no breakages or loss of power" |
Length and force adaptablity |
Reduces undesired effects |
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This one size elastic mini rod can be easily shortened and thinned to offer you complete customization of length and force.
Applications • Distalising upper molars (HG-like) • Mesialising lower molars or premolars (Aplasia or after extractions) • Cl II-corrections between upper and lower dental arch • Helping to grow the mandible forward • Retrusion of upper incisors • Protrusion of lower incisors • Midline corrections (unilateral application) • Unilateral dental Cl II correction (unilateral application) • Space closure (even single-sided) in the mandible (aplasia) |
Unique by-pass arch enables the FLEX DEVELOPER to slide back passively without force or side effects.
Unique features • Reliable • Highly durable • Length adaptable to individual need • Force adaptable to individual need • Lasting elasticity • Relockable anterior piece • Measuring gauge for quick installation • Can be combined with lip bumper or headgear • Securing mini disc for pin safety • Auxiliary bypass arch pre-bent for precise function • Small and streamline – more comfortable • Easy to install |
