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Orthodontics/Pre-surgical bite registration

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QUESTION: Dear Dr. Supan, I am a candidate for oral surgery. I am curious to find out what is the importance of the pre-surgical bite registration and how this will be used in making the surgical splint and surgical planning via computer modeling. It seems that I have a dual bite and I would like to understand more about this and how this dual bite (choosing one type of bite over the another type of bite) will affect the mock surgery, surgical planning and surgical splint. What does the bite registration produce or how is it important in ultimately helping a surgeon with the surgery. Thank you in advance for your kindness. Aura Daraba

ANSWER: Dear Aura,

Thank you for submitting a very interesting, albeit technical question about dual bites and Pre-surgical bite registrations. Please pardon the delay in responding. You wrote:

“  I am a candidate for oral surgery. I am curious to find out what is the importance of the pre-surgical bite registration and how this will be used in making the surgical splint and surgical planning via computer modeling. It seems that I have a dual bite and I would like to understand more about this and how this dual bite (choosing one type of bite over the other type of bite) will affect the mock surgery, surgical planning and surgical splint. What does the bite registration produce or how is it important in ultimately helping a surgeon with the surgery. Thank you in advance for your kindness. “

What I write here Aura are only my opinions based on very limited information. My comments should not be viewed as any form of diagnosis, definitive or otherwise, or any form of treatment recommendation.  Indeed, in the ultimate analysis all final decisions, particularly clinical ones, should only be made by qualified doctors who have had a chance to see you in person and who have had an opportunity to take and analyze proper diagnostic records.  Indeed, in the ultimate analysis all final decisions, particularly clinical ones, should only be made by qualified doctors who have had a chance to see you in person and who have had an opportunity to take and analyze proper diagnostic records.

Okay… having said  that…  your questions Aura focused on a dual bite and bite registrations.

One way to look at all this Aura is to view the teeth i9n the upper and lower jaw almost like gears which need to mesh together. Sometimes the human teeth do not mesh very well, and this is due to three main reasons. One reason is that the upper and/or lower teeth are crooked and poorly aligned, therefore preventing a proper mesh. Secondly it may be that the upper jaw containing the upper teeth and the lower jaw containing the lower teeth manifest a poor and unbalanced skeletal architecture. That is, the upper and lower jaws are not properly positioned with one another, and therefor the teeth which are embedded in the upper and lower jaws can not mesh properly either.  The third reason for a poor meshing of the teeth is a combination of the first and second conditions just mentioned.

In general, the anterior-posterior skeletal jaw relationship can be described as Class I, Class II, or Class III. An ideal skeletal relationship with good meshing of the teeth and a normal side profile is termed a Class I. In a Class II skeletal bite the upper jaw is positioned relatively forward of the lower jaw. The upper teeth therefor often appear protruded and have a “buck tooth” appearance. Such Class II architecture can be due to a normal sized upper and an undersized retro-positioned lower jaw; an over-sized forward positioned upper jaw and normal lower jaw; or finally an over-sized forward positioned upper and undersized retro-positioned lower jaw combination.

So now Aura we get to the point for your surgery and the dual bite situation. A dual bite most commonly describes a condition whereby a person can bring there teeth together in a normal Class I manner, or in a Class II with the upper teeth and jaw meshing relatively forward of the lower teeth and jaw.  The person can often easily move the lower jaw forwards to create a beautiful Class I relationship, or make the teeth and jaws mesh in a Class II relationship.

One sometimes sees this dual bite referred to as a “Sunday Bite”. This archaic term refers to people on Sundays going to Church and grinning with their best smile (Class I) while in fact they may have a non-ideal Class II skeletal (jaw) and dental (teeth) relationship.

You specifically asked about which bite:

“  . It seems that I have a dual bite and I would like to understand more about this and how this dual bite (choosing one type of bite over the other type of bite) will affect the mock surgery, surgical planning and surgical splint.  “

The mock surgery will allow pre-visualization of the end result of the surgery as well as to get an idea of just how far the jaw surgery needs to go to help achieve the ideal Class I skeletal architecture. Depending on techniques, the distance of the correction may dictate the type, number, and orientation of the surgical plates and/or screws being used to hold the jaw correction and repositioning in place.  These exercises used to be done a great deal in past years, but the advent of Cone Beam and 3D Radiography techniques and computer modeling has permitted much of these plaster cast and wax model techniques to be abandoned. I would assume that the bite and skeletal relationship being sought by the surgeons is a Class I meshing.

You also asked specifically about the use of the pre-surgical splint.  You asked:

“What does the bite registration produce or how is it important in ultimately helping a surgeon with the surgery. “  

This splint may in fact be used in surgery and will allow the surgeons to mesh the teeth together in a Class I relationship. Once this ideal meshing is achieved, the jaw surgery can finalize the position of the upper/lower jaw architecture, and use rigid fixation via plates, pins and other means to stabilize the entire upper jaw/lower jaw/upper teeth/lower teeth complex.

The surgical splints are very important because surgeries not only will change the anterior posterior relationship of the upper and lower jaws, but may also affect the transverse width (if cross bite(s) exist) of the jaws, or the left to right transverse cant of what is termed the occlusal plane.  In more simple words, imagine biting down with your back teeth on a pencil that is oriented in its long axis left to right.  Now look into a mirror. Is that pencil’s long axis parallel to say a line connecting left eye pupil to the right eye pupil, or is the pencil perhaps canted up or down on one side.

To use an aircraft orientation analogy, the surgical splint in other words Aura, can help the surgeon better control the “pitch, yaw, and roll” of the jaw positions.

If you are getting jaw surgery in 2015 Aura, please consider the following:

1)   Get a Cone Beam radiograph if possible to help identify any jaw asymmetries and imbalances in the architecture of the upper and lower jaws.
2)   Make sure that the surgeon and the Orthodontist coordinate closely, and that the surgeon in able to deliver surgically what the Orthodontist needs to produce a beautiful Class I condition.
3)   Inquire about the impact on your facial profile as well. Although soft tissues like muscle, skin, and fat can mask a great deal of change, the surgeon, using computer software, should give you a sense of what changes can be expected.
4)   As part f the informed consent process, ask both the Orthodontist and Oral Surgeon what the drawbacks and dangers are in case the surgery is not successful, or if the repositioned jaw position relapses.
5)   Finally, ask what the pros and cons are f doing no surgery at all, and simply living with what you have termed a “Dual Bite”.

Aura, this has been a very interesting question.  I hope the explanations have not been too confusing.

Paul Supan, DDS, MA, MPH
Board Certified Orthodontist

Specialist in Orthodontics
Specialist in Dental Public Health
http://www.braces.com
http://www.leesburgbraces.com

Please allow a week for a reply. I am in full time Private Practice, lecture on occasion, and involved in many volunteer activities. I am therefore not always able to respond to questions straight away. Your understanding is appreciated.


---------- FOLLOW-UP ----------

QUESTION: Dear Dr. Supan,

Thank you very much for your wonderful answer: it clarifies a lot and helps me to understand better the orthodontic-surgical process. However, I decided to ask you the previous questions because I am afraid of a possible failure of the surgery from both functional and aesthetic stand points. My major concerns are as follows and will be discussed from two perspectives: the perspective of my treating orthodontist and the perspective of the orthodontist that was imposed on me, for the pre-surgical work and planning, by the hospital where I will have the surgery. The hospital where I will have the surgery is not allowing my treating orthodontist to continue his work with me in this immediate pre-surgical period.

My condition can be described as follows: I have a Class 2 div 1 malocclusion. I have a posterior cross-bite on the right side (due to skeletal reasons; teeth were already arranged over the basal bone, in an upright position by my treating orthodontist (who I value very much!).  Lower jaw is moderately deficient (I might need 8-9 mm advancement) with mild asymmetry. Upper jaw (palate) is narrow. My face is slightly hypoplastic on the left side (it seems that this is a congenital condition).

My treating orthodontist envisaged for me the following procedures: 1) Lower jaw advancement; 2) Surgical widening of the upper jaw, with the upper jaw divided into 3 segments (1 anterior segment and 2 posterior segments). I found the plan of my treating orthodontist very good since the division of upper jaw in multiple segments will allow the repositioning and widening of the upper jaw without negatively affecting the natural, neutral position of my lower jaw, respectively of my TMJ. My treating orthodontist was always taking my bite registration by softly pushing and guiding the lower jaw strictly following its natural course/trajectory without putting any strain on my TMJ.

The hospital’s orthodontist took my bite registration in a weird way (at least it seemed weird to me since I saw the technique used by my treating orthodontist or by my dentist): he pushed back and forced to the left my lower jaw for matching the upper and lower teeth (although there is an existing asymmetry and cross-bite). By doing so, he forced my lower jaw and TMJ. I told him that that is not my bite and I showed him how my jaws are coming together. At this point he told me that I have “dual bite” and his way of positioning the lower jaw relative to upper jaw is my real bite. This was very hard for me to imagine since naturally, my lower jaw moves up-down in the way I showed him and no stress is put on the TMJ. Now, dear Dr. Supan, you illuminated me with regard to the “dual bite”: while dual bite is about moving backward-forward the lower jaw, the hospital’s orthodontist named “dual bite” a lateral, left-right, transversal movement of the lower jaw. The hospital’s orthodontist did not notice any narrowness of my upper jaw and intends to plan the surgery using 1-piece Le Fort I and lower jaw advancement so that the 2 jaws will meet in a Class 1 relationship somehow. By the way the hospital’s orthodontist took my bite registration, I am very afraid that most of my skeletal asymmetries will not be fixed but worsened. This is why I asked you about the importance of the way the bite registration is taken prior to planning the surgical moves and for the functional and aesthetic success of my upcoming double jaw surgery.  

I am aware of the fact that you are not an oral surgeon but your perspective, as orthodontist, would be helpful. If you could be kind and spend a bit more time for answering me to the concerns that I mentioned previously and based on the information I just gave you, I will be very grateful to you! I fully understand that many people are asking you opinions and you have a limited time, but your answer will be very important for me so that I will make more informed decisions based on the different ways in which my bite registration was recorded. Thank you very much!

Aura

Lower Jaw Angle
Lower Jaw Angle  
ANSWER:
Hi Aura,

I am enjoying these exchanges. I apologize to you and other readers for the delay in responding to the series of latest inquiries. I accidentally tipped tea onto my laptop’s keyboard and the machine promptly dies. I have since transferred the needed files.

Again Aura, as always, what I write here are only my opinions based on very limited information. My comments should not be viewed as any form of diagnosis, definitive or otherwise, or any form of treatment recommendation.  Indeed, in the ultimate analysis all final decisions, particularly clinical ones, should only be made by qualified doctors who have had a chance to see you in person and who have had an opportunity to take and analyze proper diagnostic records.  Indeed, in the ultimate analysis all final decisions, particularly clinical ones, should only be made by qualified doctors who have had a chance to see you in person and who have had an opportunity to take and analyze proper diagnostic records.

In your recent  follow-up question Aura you provided a great deal more information. I am struck by the fact that this likely is a much more complex case than I originally thought based on earlier inquiries. As such, there may be varying “opinions” between your two Orthodontists on how to proceed with treatment. From a professional perspective, I have always experienced cordial and friendly communications during multi-disciplinary treatments, even when multiple doctors of the same specialty are involved. I trained at a major medical center where cleft palate patients, as well as others with cranio-facial anomalies such as Hemifacial Microsomia were treated.

Let us look at some of the points you raised in your last follow-up:

(1)  Lower Jaw Retroposition & Verticality.

“   I have a Class 2 div 1 malocclusion. I have a posterior cross-bite on the right side (due to skeletal reasons; teeth were already arranged over the basal bone, in an upright position by my treating orthodontist (who I value very much!).  Lower jaw is moderately deficient (I might need 8-9 mm advancement) with mild asymmetry. Upper jaw (palate) is narrow. “

Kudos to your first Orthodontist for helping manage this dental portion of your orthodontic problem. As I am sure you are aware, you have an unbalanced skeletal architecture of the jaws n addition to certain dental orthodontic problem involving the teeth, An 8-9 mm lower jaw advancement may or may not be “moderate”. The 8-9 mm deficiency of the upper vs. the lower jaw may be due to many reasons, and not simply a “ small lower jaw”. If you view somebody from the side and look at their facial profile, you may notice that the lower border of their jaw angles slightly down. Some patients have very “vertical” lower jaws, so that the jaw tends to point downwards more so than forwards when compared to a “normal” jaw. This verticality of the lower jaw can impact the degree to which the lower jaw is retro-positioned behind the upper jaw.  In your case, I am not completely clear about the nature of the 8-9 mm advancement and whether any excess verticality and or left vs. right lower jaw asymmetry is playing a role.

The slight narrowness of your upper jaw, which likely is helping to contribute to the cross-bite, is fairly common.  You also said,   " My face is slightly hypoplastic on the left side (it seems that this is a congenital condition)”.  If other facial asymmetries, possibly hypoplastic related, exist higher in the face, and whether upper jaw expansion will have an effect is worth considering. Hopefully any effects will be for the better.

This is all very complex. Again please understand that I am expressing general thoughts based on your written comments. I have never had the opportunity to review any clinical records, nor have I had a chance to examine your orthodontic condition in person.

Attached  is an image courtesy of the University of Rochester Medical Center showing the angle of the jaw. Note that the inferior border of the jaw in this image is fairly normal and somewhat horizontal. In very vertical jaw cases the angle can be far steeper, meaning that overall the jaw is positioned  less forward horizontally, and down far more vertically.

http://www.urmc.rochester.edu/news/story/uploadedimages/facial-aging_2800_312x40

(2) Upper Jaw – Narrow or Not?

The second point to discuss is the question about what to do regarding surgery, if any, to the upper jaw.  You stated:  “ The hospital’s orthodontist did not notice any narrowness of my upper jaw and intends to plan the surgery using 1-piece Le Fort I and lower jaw advancement so that the 2 jaws will meet in a Class 1 relationship somehow.”  Apparently your first treating Orthodontist did notice an upper jaw transverse discrepancy, which may in fact help explain the posterior cross-bite and is consistent with your observation that “My face is slightly hypoplastic “.

It would seem that a cone beam 3D diagnostic imaging work up reviewed by an Oral and Maxillofacial Radiologist would settle this issue. The radiologist could compare your metrics with certain norms and standards, as well as characterize the upper jaw size relative to the lower as well as other surrounding facial anatomy. You can look at this web site for more information on the expertise and services offered by oral and maxillofacial radiologists. OMR  is an ADA recognized dental specialty much like Oral and Maxillofacial Surgery, Orthodontics and Dentofacial Orthopedics, Oral Pathology, etc.

http://www.aaomr.org/?page=OMRasaCareer

Once you have better established the extent, if any to which the upper jaw is narrow/deficient, and how this discrepancy interacts with the other parts of the face including your facial profile and bite relationship with he existing lower jaw, you will be able to gain a better sense of direction regarding a surgery strategy. Obviously at this point I do not have any surgery suggestions.

(3)  The Bite Registration Issue

Now regarding the bite registration. You wrote:

“The hospital’s orthodontist took my bite registration in a weird way (at least it seemed weird to me since I saw the technique used by my treating orthodontist or by my dentist): he pushed back and forced to the left my lower jaw for matching the upper and lower teeth (although there is an existing asymmetry and cross-bite). By doing so, he forced my lower jaw and TMJ.  “

I think what your hospital Orthodontist is trying to see is if a harmonious bite relationship can be achieved with only a lower jaw surgery. During his examination he was manipulating the lower jaw to one side to see if he could achieve a better meshing of the teeth. I believe he may be trying to determine if he is able to relieve the cross-bite with a lateral shift of the lower jaw. I am not able to understand why substantial backward pressure is being put on your lower jaw when a lower forward advancement is being planned. Perhaps the meshing issue is being approached via two different strategies. Orthodontist #1 wishes to broaden the upper jaw, advance the lower jaw, and with some prior orthodontics , achieve a harmonious bite. Orthodontist #2 perhaps wished to achieve a harmonious bite with transverse and anterior-posterior lower jaw repositioning and a single piece upper jaw repositioning. I think the key may be to determine whether there is a reduced  upper transverse dimension.

In surgical orthognathic cases, the coordination between the Orthodontist and the Oral Surgeon needs to be ongoing and from the beginning. The initial treatment plan which outlines the proposed orthodontics as well as orthognathic surgery requires input from both doctors. In some cases, pre-surgical orthodontics is done to set the patient up for the surgery, the surgery takes place, and then a third final portion of treatment occurs with post surgical orthodontics to fine tune the bite and the aesthetics.

Aura, in your case there seems to be a difference of opinion regarding the surgical strategy, which is appearing only now. One Orthodontist seems to think the upper jaw transverse dimension is fine, while the other believes it to be deficient.  The surgical strategy envisioned by your first orthodontist, as well as the pre-surgical orthodontics you have received so far seems to not fully coordinate with the surgery and orthodontic management envisioned by your hospital Orthodontist.

(4) Solutions for your Consideration

A) Establish what the nature of the lower jaw asymmetry, size, and verticality and for what reasons said advancement is being done. The use of  3D images and an oral maxillofacial radiologist to help interpret this will help to establish the diagnosis and to formulate an appropriate surgical treatment plan.
B) Determine whether the upper jaw has a normal or narrowed transverse dimension relative to surrounding anatomical structures and normative anatomical values, trans-jugal measurements, etc.
C) Have the two Or6hodontists try to again better communicate to see if a common strategy can be developed. If necessary get a third opinion and employ an Oral Maxillofacial radiologist to interpret the 3D images.
D) Before committing to surgery, have an established written treatment plan and protocol in place outlining the already completed pre-surgery orthodontics, the actual surgical orthognathic procedures, and any post surgical follow up orthodontics.
E) Ask if various treatment options are available. Are there various comprehensive vs. less complex surgical options available? If so what are the relative merits of each, and what are the risk/benefit ratios?
F) Insist on reviewing and initialing/approving each and every element of the Informed Consent Documents for surgery as well as the orthodontics.
G) Finally, because I see that you are writing from Iowa, USA the University of Iowa has a world class graduate Orthodontic Residency Program and you may wish to see if an independent consultation there is available. The option of whether to use a single vs. multiple piece upper jaw surgery approach may well be better explained to you given the University program’s considerable resources.

Aura, there is an old saying  “buyer beware”. In your case, I would counsel patient beware. I hope that the two Orthodontists will be able to resolve their two perspectives. I would welcome further follow up questions, particularly if an Oral Maxillofacial Radiologist becomes part of your treatment team.

Paul Supan, DDS, MA, MPH
Board Certified Orthodontist

Specialist in Orthodontics
Specialist in Dental Public Health
http://www.braces.com
http://www.leesburgbraces.com

Please allow a week for a reply. I am in full time Private Practice, lecture on occasion, and involved in many volunteer activities. I am therefore not always able to respond to questions straight away. Your understanding is appreciated.



---------- FOLLOW-UP ----------

QUESTION: Dear Dr. Supan, thank you very much for the extensive answers to my questions; you clarified many aspects what have to be taken into consideration by both medical team and by me, as a patient. I was afraid to not flood you with to many details. I find very good your idea of discussing with an Oral Maxillofacial radiologist to interpret the 3D images. I will need to find one in Iowa or better in New York, where I will have the surgical treatment. When I will get the 3-D scans, I would like to send them to you, if you agree. I do not know if these medical documents can be send using this website or by using personal email. I am very grateful for educating me as a patient. Best regards, Aura

Answer
Dear Aura,

I appreciate your methodical approach to evaluating each and every aspect of your potential surgical orthognathic plan, particularly because of possible differences in diagnostic work up and resulting treatment plans.  I believe that additional input from a specialist in dental radiology will provide you and the surgical team with a better sense of direction regarding the actual anatomical abnormalities and jaw architecture incongruities.

The radiologist will provide, among other things, a review of the anatomical finding, but not necessarily comment on the surgical or orthodontic treatment plans. The will be left to the two other dental specialists.
In terms of locating a dental radiologist, please go to the following link and contact the American Academy of Oral and Maxillofacial Radiology:

http://www.aaomr.org/general/?type=CONTACT

Their telephone contact number is:  (217) 529-6503

As I am sure you are aware, I am not an Oral and Maxillofacial Radiologist. In fact the American Association of Orthodontists in their malpractice continuing education programs specifically counsels Orthodontists to be careful about diagnosing advanced imagery such as 3D, cone beam, functional MRI, PET scans, etc.

You wrote:  “When I will get the 3-D scans, I would like to send them to you, if you agree. I do not know if these medical documents can be send using this Webster or by using personal email. I am very grateful for educating me as a patient. “

The suggested protocol is to refer these for reading and interpretation to a dental radiologist. I therefore would ask that any images taken be forwarded electronically to an oral radiologist for interpretation. Aura, you may wish to pre-check with your insurance plan to see if this can be covered. Usually diagnostic services are very generously covered by your medical or dental plan. Also, the radiology procedures can sometimes be filed as a medical procedure in case your dental coverage excludes such coverage.

I respect the fact that you are diligently doing all this preparation prior to committing to the procedures. I think you will serve as an excellent role model to others in similar situations. I hope the links and telephone numbers will help. As I stated in an earlier reply, the University of Iowa Dental School is one of America’s flagship dental colleges, and their Department of Orthodontics is absolutely top drawer.  I think that at this point you have quite a few resources at your disposal.

Aura, please stay in touch and let me know how all this works out. Also, please rate the feedback, as I did have some computer malfunctions in the past two weeks. Thank you.

Paul Supan, DDS, MA, MPH
Board Certified Orthodontist

Specialist in Orthodontics
Specialist in Dental Public Health
http://www.braces.com
http://www.leesburgbraces.com

Please allow a week for a reply. I am in full time Private Practice, lecture on occasion, and involved in many volunteer activities. I am therefore not always able to respond to questions straight away. Your understanding is appreciated.

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Paul Supan, DDS, MA, MPH

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First may I say please set your questions to Public so other readers can benefit from the response. Also, if you look at my comprehensive answers, they are not short 1 or 2 paragraph quickie replies that anyone can type out in < 5 minutes. Instead I often will ask other colleagues in other specialties for their advice in order to provide you the questioner with a more interdisciplinary perspective. This all takes time. I ask for readers to therefore allow 5-7 days. You will be rewarded with a very detailed response.

Because of the nature of Orthodontic questions, any pictures of the teeth and X-ray images would be very helpful. If you write to me and explain that you have crooked overlapping front teeth can be interpreted in many many ways, and my goal is to provide a specific response that meets your needs.

I hold double specialty credentials. I am Board Certified in Orthodontics and Board Eligible in Dental Public Health. I welcome questions regarding Braces, Invisible Braces, & Invisalign, as well as issues involving combination Cosmetic Dentistry and Orthodontic treatment. Orthodontics alone sometimes is not enough to achieve that perfect smile. Gingival (gum) re-contouring, tooth reshaping, bonding and other services are sometimes needed. I also have substantial experience in the areas of Infection Control and Sterilization in the Dental Environment. My personal websites braces.com and Leesburgbraces.com are non-commercial for information purposes only and may provide you with some background to more precisely frame your question for allexperts.com.

Please allow a week for a reply. I am in full time Private Practice, lecture on occasion, and am involved in many volunteer activities. I am therefore not always able to respond to questions straight away. Your understanding is appreciated.

Experience

Board Certified Orthodontist (ABO Diplomate) with over 25 years of Private Practice experience. Second Specialty Certificate in Dental Public Health with research experience at NIH, and Epidemiology Training & Research at Harvard, NIH, and the Centers for Disease Control (CDC) in Atlanta. Postgraduate Masters degree from the Harvard School of Public Health, as well as a Master of Arts Degree in Education.

Organizations
American Dental Association, American Association of Orthodontists, Academy of General Dentistry, College of Diplomates of the ABO, OSAP - Office Sterilization & Asepsis Procedures Organization, Others

Publications
Available upon Request.

Education/Credentials
BS College of William & Mary, DDS Medical College of Virginia, Masters of Public Health (MPH) Degree Harvard School of Public Health. Dental Public Health Specialty Certificate from NIH. Orthodontic Specialty Certificate from University of Rochester Eastman Dental Center. USPHS clinical research experience at NIH, and Epidemiology Training & Research at Harvard, NIH, and the Centers for Disease Control. Fellow of the Academy of General Dentistry (FAGD), and Fully Board Certified Diplomate of the American Board of Orthodontics. Board Eligible in Dental Public Health. Visiting Adjunct Associate Professor at the Meharry Medical College School of Dentistry, Nashville, Tennessee.

Awards and Honors
Available upon Request Please see my personal websites braces.com and Leesburgbraces.com for further personal background.

Past/Present Clients
Available upon Request

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