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Orthodontics/lower jaw position at rest

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Question
Dear Sir,
When jaw is in relax position, does the lower jaw more forward/backward/same compared when i bite? when i bite  my anterior teeth have slightly overjet so my edge of lower teeth do not touch the back of my upper anterior teeth. The problem is there are so many times when i slept on bus,train in sit down position, my lower jaw will upward a little and hit the edge of my two upper central incisors.It seems that the lower jaw sometimes are more forward in the rest position. Anyway, i have minor open bite. my two upper central incisor almost do not overlap my lower teeth (0mm)and the two laterals have open bite about (1-2mm). Is this an abnormal rest position?

Answer

Hello Ely,

The issue you describe can be affected by many factors. Traditionally many dentists have viewed the bite using terms like centric occlusion and centric relation. In recent years there have been disputes whether such terms should be interpreted in an absolute sense.

Do realize that the lower jaw is connected to the skull via a joint called the temporo-mandibular  joint.  This is more or less a ball and socket type set up with the difference that the lower jaw not only can rotate within the socket but also gently  glide out of and then back into the "socket". The anatomical nature of the "ball" as well as the " socket", and the little disc or meniscus separating the two can impact the way the jaw opens up.

In addition, the teeth, particularly the canines can also often affect how the upper and lower jaws eventually meet and "occlude". When orthodontists check the bite of a patient they must be careful to do it both in the upright as well as horizontal position, as the two may differ.

In your situation, the bite relationship seems to be dictated by the skeletal architecture you have, and you also mention the fact that you feel you have a minor "open bite". To answer your question, when a person opens their mouth the lower ja tends to firs open and rotate down and then sightly forwards. If you were to mark the lower tip of the chin and watch yourself in profile, you might see a tear-drop shaped open and closing pathway or orbit defined. This path of opening and closing, viewed wither in profile or from the front, can experience deviations as noted due to the anatomy of the ball and socket area (condyle and glenoid fossa), the disc ( meniscus), the dental occlusion due to canine guidance or lack thereof, and many more factors.

So the final answer to your question is that the opening and closing pathway can vary, but generally is open, down, and forward, and then the opposite s you close your mouth. I hope this has been helpful Ely.

Paul Supan,  DDS, MA, MPH
http://www.Leesburgbraces.com  

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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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