Pre-Delivery of the Crown Bite Jumping Appliance (Herbst)

by Paula Allen

Pre-Insertion Check List: 

Several Days before the patient’s appointment check to make sure that you have the (Herbst) appliance and it’s components back from the laboratory. Review the prescription sheet to determine that the appliance has been made to specification and make sure that the work models and appliance identifications match your patient.

 Note:

Every office should have a starter Herbst Accessory Kit. The kit will give you an ample supply of spare components and advancement shims. Components and shims can be reordered from suppliers and recycled in your office.

Appliances need to be checked for accuracy before the patient’s appointment. Minor adjustments made early can save clinical production schedules. Place the fabricated Herbst crowns back on the work models. Line up the guide lines on the upper and lower models, or check the prescription sheet for the advancement requested, and place the upper tube and lower rod into the axles passively (you may but do not have to place screws)

Tubes and rods proper length: advancement correct

If the upper tubes seem too long or short corrections can be made at this time.

Upper tube is too short

When the upper tube is too short, this is an indication that the appliance will not advance the patient properly. Place a new tube over the axle, line up the advance guidelines and mark the tube for proper length. Cut the tube with a disc or 1171 bur, and smooth edges with a heatless stone.

If the upper tube needs minimum adjustment and the lower rod is long enough, you may be able to add a shim to the lower rods to compensate for the upper tubes being too short.

When elongating an upper tube before initial placement, you will most likely have to lengthen the lower rod as well, or the patient will probably disengage upon opening.

 Lower Rods too short or long:

The Lower rods seem too long or too short, corrections should be made at this time.

Lower rod is too long

If the lower rod is too long, it will impinge on the soft tissue in the back of the cheek. The lower rod when engaged into the upper tube should not extend any further than the middle to mesial of the end of the upper screw. To shorten a lower rod place it in the upper tube, place passively over the axles holding the work models at the advanced position and mark the rod. Cut the lower rod with a disc or cutting pliers and round off the end with a stone.

Note:

If a lower rod is too short, you may correct the length by replacing it with a longer rod and following the same procedure as outlined above.

Check that the Midlines are Correct:

Midline Off: Frontal and Buccal views

Midline Corrected: Frontal and Buccal views

If the work models show a deviation and the midlines are off you can add a shim of the appropriate length to correct the discrepancy. Below note that the lower midline is off to the left, so a shim has been added to the lower left tube shifting the mandible to the right, correcting the midline. Patients will occasionally present with this problem during Herbst treatment, correction is easily made at the chair.

Midline Off and Corrected

Check Cantilever Arms

Check that the mandibular cantilever arms are aligned properly. If they are too far from the teeth they will cause cheek irritation. If they are tipped too far inward they will impinge on the gingival tissue.

Cantilever Arm out too far and Cantilever Arm Corrected

It is very important to check for and correct this problem before cementing your appliance. If you notice a potential problem correct as best you can and recheck once again when you fit the patient before cementation. Once the appliance is cemented on you would most likely have to remove the lower crown and mechanism. A tremendous loss of patient confidence, time and money, should the quadrant be damaged and have to be remade.

Adjustments to the mandibular cantilever arms are usually made with three prong headgear pliers. Any up-down, in-out, or torque corrections should be made at this time.

Right Cantilever out too far
Correcting w/pliers
Right Cantilever Corrected 

Check Occlusal Rests

Occlusal Rests need to be checked for their approximation to the teeth. This particular procedure will need to be re-checked at the trial fit of the appliance. Rests vary in design and function.

Occlusal rests are placed on second molars to ensure that there is no super eruption of those teeth during Class II correction. Rests on lower permanent or primary pre-molars help to keep the cantilever arms from tipping and the molars from rotating. Occlusal rests are sometimes used in conjunction with expanders to control the molars from tipping and enmasse expansion of the entire arch.

Rests on the occlusal surface of the upper or lower permanent first or second bicuspids or primary E’s or D’s are usually secured with a light cure composite. As with crowns, occlusal rests should be micro etched to ensure a good bond.

Adjustments are easily made with Howe or Bird Beak Pliers. However, caution should be taken when adjusting rests as they can break if annealed too much.

Pearls

Pearl#1: The addition of a 1/4" diameter elastic around the lower mandibular cantilever arms will allow the patient to place a cotton roll through the elastic helping to alleviate any discomfort to the cheek area while the patient is getting accustomed to the appliance during the first week.

Pearl #2: Notching the crowns will make crown removal much easier.

Maxillary crown notched Mandibular crown notched

NEXT ISSUE: CLINICAL INSERTION

The Orthodontic CYBERjournal wishes to thank both Paula Allen for her article and Allesee Orthodontic Appliances (AOA) for permission to publish this information.

About the Author: Paula is the clincal liason for Allesee Orthodontic Appliances (AOA). Many of you know Paula from her 30 years in the industry. She worked in an orthodontic practice for fourteen years and has attended and lectured at continuing education seminars, presented staff and doctor's clinics at the Great Lakes, Midwest, Southern, and Mid-Atlantic constituent meetings, as well as, for the American Association of Orthodontists. Paula has visited and interacted with hundreds of orthodontic offices. Her experience in orthodontics covers a wide range of areas.

Clinical management of the bite jumping appliances, especially the crown versions is one of the areas in which she has been extremely active over the last ten years. Her involvement in "hands on" clinical systems and techniques has given her valuable insights into what must be done in the orthodontic practice from a clinical perspective to facilitate predictable, profitable and excellent treatment results.

She can be reached at:

Paula S. Allen Clincal Liason Allesee Orthodontic Appliances (AOA) 13931 Spring Street Sturtevant, WI 53177 USA

or more directly:

Paula S. Allen Clincal Liason (AOA) 463 Club View Drive Lawrenceville, GA 30043 USA

1-800-990-3485