Dr. Faulkner: You have used the Herbst^{TM **}style appliance for a number of years, how have they evolved in your office?

Dr. Mayes: I started in the early '80's with the old standard design consisting of stainless steel crowns on the upper 6's and on the lower D's or 4's and bands on the lower 6's. An .045" lingual bar was soldered to the lower crowns and bands. From there I moved to stainless steel crowns on the upper 6's and an acrylic lower either removable or bonded. My dissatisfaction with the acrylic lower and with the D's loosening during treatment led to the next step: stainless steel crowns on the upper 6's and a bonded metal framework to a lower arch. This procedure had its own inherent problems and the clean up was horrendous. Ultimately, in the mid '80's we started the cantilever bite jumping design (CBJ), pretty much as it is it today. So in a nutshell there's the evolution of the CBJ in my practice.

Dr. Faulkner: Describe your current design. What are the advantages?

Dr. Mayes: My current design utilizes stainless steel crowns on the upper and lower 6's. I incorporate a trans-palatal bar if rapid palatal expansion has been done. On the lower 6's the cantilevers come forward to the mesial of the first bicuspid area or approximately to the middle or the anterior portion of the D's. Attaching on the lingual of the lower first molar crowns is an .045" lingual bar which rests well up on the cingulum of the lower anteriors approximately at the junction of the middle 1/3 and lower 1/3 of the teeth . The advantages of this design are multiple. Because of its simplicity and rigidity, it is basically a fool proof appliance. Positioning the lingual bar as described allows the appliance to be made without occlusal rests. This is aided by having the cantilever arms up and parallel with the tooth structure so we have as small a vertical vector of force as possible trying to tip the lower arch forward.

Dr. Faulkner: What is your appointment/procedure schedule for CBJ patients?

Dr. Mayes: Here is a typical schedule for treating a Class II (skeletal) patient with the Cantilever Bite Jumping Appliance.

A total of 15 Visits, 21-24 months active treatment, 3 total archwires.

Dr. Faulkner: What has been the response/acceptance from parents and patients?

Dr. Mayes: Our response and acceptance from both parents and patients has been markedly better than it was with the acrylic appliances. From the patient's point of view, there doesn't appear to be much difference between designs that use a stainless steel crown on the lower D or 4 and the first molar crown only used in the CBJ. Parents and patients do appreciate having the appliance delivered in a single visit of 30 to 45 minutes duration.

Dr. Faulkner: Were non-compliant patients the impetus for developing the CBJ?

Dr. Mayes: There is no doubt that non-compliant patients were part of the reasons for developing the CBJ. However, it became harder and harder to justify the retraction of a normal upper jaw, back to a deficient lower jaw with headgear and elastics. With the CBJ I get better, more balanced profiles than I was able to get with headgear and elastics.

Dr. Faulkner: Are you using the CBJ for orthodontic or orthopedic movement?

Dr. Mayes: We use the CBJ for both. However, there is a wide range of responses depending on the way the appliance is adjusted. Basically, if you want more skeletal change, jump the patient all the way from a Class II to an edge to edge bite and maintain them there for approximately 12 months. The skeletal response will be achieved in 5-7 months, however, the slower muscular adaptation will doom you to a large relapse if you don't leave the appliance for a minimum of 12 months. If more dental change is desired, advance the lower jaw incrementally 3 mm's every 2 months, until an edge to edge is achieved and maintained in the patient for 9 months. This tends to produce more dental and less skeletal change.

Dr. Faulkner: What do you think the biological responses are? What studies or follow-up have you done?

Dr. Mayes: The biological response of the lower jaw being postured forward with the CBJ are muscular adaptation along with bony readaptation to the tension placed on the head of the condyle. This leads to a more balanced facial profile . Growth cartilage must be present for the bony changes to occur at the condylar head. This is based on 125 consecutive cases studied in our office. There were 5 different parts to the study consisting of 25 consecutive cases in each of the following categories:

1. The CBJ incrementally advanced 3 mm's until edge to edge was achieved and held there for 9 months.
2. The CBJ advanced from Class II to an edge to edge and maintained for 1 year.
3. The CBJ advanced from Class II to an edge to edge with maxillary braces on.
4. The CBJ advanced from Class II to an edge to edge with upper braces and a lower lip bumper.
5. The adult changes.

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Portions of this study were published in past issues of "Clinical Impressions". It will be published in full soon, in both the "First International Baylor Orthodontic Symposium" and an Ormco publication "The Bite Jumper's Bible".

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Dr. Faulkner: Could you use this appliance for anchorage?

Dr. Mayes: We use this appliance for anchorage primarily in adults. Due to the lack of growth cartilage at the head of the condyle, you get mostly a dental correction with distalization of the upper molars, however, you will achieve some mesial migration in the fossa. With adults we leave the appliance in for anchorage and retract the upper dentition against the appliance before its removal.

Dr. Faulkner: Does it make any difference if second molars are erupted?

Dr. Mayes: Clinically, I do not see any difference if second molars have erupted. Most of our cases are treated when the second molars are coming in because our ideal scenario is to go straight from the CBJ into full appliances. This goes along with my philosophy of getting to a Class I uncrowded case before the Orthos^TM* straight wire appliances are placed and have the patient in full fixed appliances for as short a time as possible (8-9 months).

Dr. Faulkner: How do you know when you have accomplished your goals with the appliance? Do you strive for a "super Class I":? Are you taking tomographs of the TMJ?

Dr. Mayes: We treat the patients to a "super Class I" or edge to edge occlusion. This allows for approximately 2 mm's of dental relapse. How do we know when we are finished with the appliance? - We follow the pre-treatment transcranials with post-treatment transcranials. After the hundreds of CBJ's that we have done we know that the bone will have altered and changed in 5-7 months. However, we have to allow time for the muscular adaptation to reduce relapse as much as possible. One other thing about tomographs. They are not as reproducible as transcranials for condylar position. Tomographs have to be taken in the exact same cut of the condyle to be as accurate as a transcranial. Therefore, in most offices transcranials will be much more accurate for condylar position than tomographs.

Dr. Faulkner: If you use a CBJ in "Phase I" treatment, how do you hold your gain?

Dr. Mayes: We try not to use CBJ's in "Phase I" treatment because the typical "Phase I" patient will have more growth and we know we probably will have to use the appliance again. However, if the parents desire Class II correction, we explain to them that we can not alter the genetic potential to grow as a Class II and we will probably have to use the appliance again. I have no problem with this other than it is not as efficient as doing it all in one phase. The gain that we have achieved is maintained, as best as we can, with our standard retention program which is polypropylene upper retainer and a lower lingual bar.

Dr. Faulkner: What age group or stage of development do you feel is ideal for treatment with the CBJ? What role does the appliance have in adult treatment? (other than TMJ)

Dr. Mayes: I feel that most any age group is ideal for treatment with a CBJ. However, because of the appliance size you may have some soft tissue impingement in younger children. Also, as we do less early treatment and more single stage treatment, we prefer to use the appliance at a later age. We also use the appliance in adult treatment primarily to gain upper molar distalization and leave the appliance in place for anchorage during retraction of the upper dentition.

Dr. Faulkner: Do you ever see total or major relapse? If yes, to what do you attribute this response?

Dr. Mayes: Yes, we expect a relapse of approximately 2 mm's and incorporate this in our appliance design. When we were not leaving the appliance in place for a full 12 months, we were getting more relapse due to incomplete muscle adaptation. Also, the earlier you treat patients, and, the more growth they have left, the more relapse you will experience. For this reason we tend to treat later rather than earlier. Our ideal treatment timing is to be coming out of the CBJ when we can get bands on the lower second molars for our orthodontic stabilization.

Dr. Faulkner: Is it possible to design a mouth guard to fit the appliance? If not what do you advise for sports activities?

Dr. Mayes: I do not know of any mouth guards that are designed to fit this appliance. We have our patients purchase the type of mouth guard designed to be soaked in warm water. They are advised to trim it with scissors and skip the warm water soak. This will give them as much protection as possible. There may be some legal protection for the practitioner because it was not a clinically fabricated or adjusted mouth guard. Check with your own legal eagles on this.

Dr. Faulkner: What kind of damage or injury have you seen from a blow to the jaw of a patient wearing a CBJ appliance?

Dr. Mayes: The only type of damage or injuries that I have seen due to a blow to the jaw is a perforation of the soft tissue of the cheeks around the screw heads, either on the cantilever or on the lower anterior area of the appliance. This can be severely reduced by utilizing a posterior separator on the axle before placing the rod on the lower cantilever axle. This moves the rod and tube assembly laterally and helps keep the cheek away from the screw head.

Dr. Faulkner: Do you think there is an application for the CBJ in TMJ patients?

Dr. Mayes: Yes, I do feel that there is good application of the CBJ in TMJ patients. Any time we can distract the mandible forward and take pressure off the joint, there is a chance for healing and repair. I know a lot of orthodontists who use removable Herbst^TM type appliances to allow their patients to achieve relief, particularly with night time wear. I, personally, do not use the CBJ to treat TMJ patients. I use a neuromuscular orthotic. I have no qualms whatsoever in using the CBJ to achieve dental movement during orthodontic stabilization of the lower jaw, after we've achieved patient comfort with an orthotic.

Dr. Faulkner: Are you going to expound on the use and construction of the Frozat in any future publication?

Dr. Mayes: Yes, I've already written an article on the Frozat which will be published in the October or January issue of Ormco's "Clinical Impressions". It discusses utilization and adjustment of the Frozat. We go over in detail the three types of adjustments that can be made and what the results of each of the adjustments are. Basically, the appliance can be adjusted to distalize molars, expand buccal segments or a combination of the two.

Dr. Faulkner: One of our readers was curious as to what type of stainless steel crown you use and do you need to festoon to gain adequate fit?

Dr. Mayes: We prefer the Ormco crowns. We also like Unitek crowns but find that the Ormco crowns are approximately 1.25 mm shorter and rarely require trimming. As far as festooning, if we have a decent crown fit, we only festoon the mesial and distal. If the crown fits very loosely then we festoon all the way around the crown.

Dr. Faulkner: We would like to publicly thank you for your contributions to the orthodontic community by developing the CBJ. We would also like to express our gratitude for your willingness to be interviewed by the OC-J and hope that we will hear from you again.

Dr. Mayes: I would like to thank The Orthodontic CYBERjournal for offering me this opportunity to answer these questions and compliment the OC-J for the great job they are doing with their web site. You are offering a unique and exciting service for the orthodontic profession. Thanks again.

*Cantilever Bite Jumping appliance (CBJ), bite turbos, and Orthos are registered trademarks of Ormco Corporation.

**Herbst is a registered trademark of Dentaurum Corporation.

Read the previous article from Dr. Mayes published in Volume I, Issue 3.

	Dr. Joe Mayes received his D.D.S., M.S.D. and Certificate in Orthodontics from Baylor College of Dentistry and is engaged in private practice in Lubbock, Texas.
	Dr. James Faulkner graduated from Georgetown University Dental School and received his certificate in orthodontics from Boston University in 1982. He is a Diplomate of the American Board of Orthodontics and is in private practice in Springvale and Biddeford, Maine.