(A) In the original appliance, the pendulum springs were mounted in the center of the Nance appliance. This created a great deal of tongue irritation. The springs are now inserted into a 6 to 8 mm shelf on the distal of the large Nance button. They curve in the direction of the palatal vault so that the entire spring is virtually below the level of the acrylic. Whenever the patient's tongue touches the appliance in speech or swallowing, it contacts only the acrylic, greatly improving patient comfort. This also makes polishing of the acrylic Nance button easier.
Updated design of the Pendulum Appliance (46KB)
(B) An expansion screw is incorporated in any case where some arch form change or expansion is necessary (most Class II malocclusions); this is then referred to as a Pendex Appliance (Pendulum with expansion). This negates the need for an horizontal adjustment loop in the Pendulum spring, as expansion of the molars is handled by activation of the jackscrew, and further simplifies the spring and enhances patient comfort.
(C) Whenever torque control on the molars is not necessary and an outward tipping of these teeth is desirable (again most Class IIs), the distal extensions of these springs are not recurved into the molar lingual sheath. Rather, the .032 TMA wire is simply bent at a right angle to fit very loosely into the lingual sheath. This greatly improves ease of the spring placement and readjustment and also helps avoid breakage at this critical point on the spring.
(D) The appliance is practically always bonded in place with four rests. In previous appliance designs, a banded first bicuspid was used as the sole retention of the Nance button. As the Pendulum springs have a tendency to lift the back of the Nance button, there was often undesirable tipping of the bicuspid and tissue impingement at the anterior border of the appliance. Occlusal bonding of the appliance on both permanent and deciduous teeth has proved to be very stable and greatly simplifies appliance placement.
New Pendex-Initial Placement (66KB) 
I have found that it is not necessary to have a precise fit of the spring into the lingual sheath and that the appliance can be fabricated on a model without having the first molars even banded (or an impression of them). The laboratory can estimate the position of the lingual sheath quite accurately given the length and resilience of the TMA spring. I take the impression for the Pendex Appliance at the time of initial records. Separators are placed and the molar bands cemented along with the Pendulum Appliance at the subsequent appointment. This aggressive approach greatly reduces the number of patient appointments necessary.
The Pendulum springs are activated with a 90º bend in the center of the helices (so that they are then parallel to the midsagittal plane). Each distal extension of the spring is then fitted into the molar lingual sheaths using a Weingart plier. The appliance will be thrust forward of the palatal vault at this time. The occlusal surfaces of the anchor teeth have been previously etched. The appliance is pushed up against the palatal vault with finger pressure and bonded in place using a CR syringe to exude the bonding medium followed by a mixture of the sealants to smooth the surface. The appliance is held in place for two minutes and then released.
I have previously reactivated the Pendulum springs intra-orally to improve the activity. This is cumbersome and can be somewhat uncomfortable for the patient. Over time, I have discovered that this reactivation is simply not necessary. If the appliance is preactivated and placed as I have described above, one needs only watch as the appliance expresses itself over a two to three month period. After the first three week period, I will instruct the patient to begin activation of the mid-palatal jackscrew. It is activated one turn every three days. Six to eight activations are ample in most Class II malocclusions .
Initial Models of Case Above (132KB)
After appliance removal a Quick-Nance appliance is routinely placed. If the upper arch is bracketed, there is no attempt to retract the buccal segments immediately. Elastic chain to the buccal segments along with the periodontal ligament rebound can serve to cause impingement of the smaller, stabilizing Nance button. When an archwire is placed, omega stops against the molar tubes help hold the molars in their distalized locations. The buccal segment teeth are then nursed slowly to avoid anchorage loss or tissue impingement by the Nance button.
A permanent dentition Pendex Appliance (66KB)
A Quick-Nance (Hilgers) (66KB)
Special thanks to James J. Hilger's, D.D.S., M.S.
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