Orthodontics/Lip Biting

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Question
Hello:

I have had braces on my teeth on two separate occasions. After I had the braces removed after the second time, I have from time to time been biting by lower lip while eating on the left side in the same place.  What would cause this situation of biting my lip in the same place while eating?

I do not have x-rays or any pictures to send so that you can better understand my situation.  

I thank you for your reply.

Answer
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Hi Kenneth,

Your question is very interesting because I actually have the same problem. At the most unexpected times, I seem to sometimes mash down on my lower lip. It is always in the same place, namely on my lower left. Just as human finger prints and the human dentition are unique, there seem to be no set patterns why some people bite their lips. You wrote:

“  … I have from time to time been biting by lower lip while eating on the left side in the same place.  What would cause this situation of biting my lip in the same place while eating?  “  

Let’s look at a few associated issues.

The upper and lower front teeth are called incisors because they are used to incise or cut into food, much like a pair of scissors  whereby the blades strike each other thereby cutting a piece of paper for example. The incisors normally would function to say bite into an apple, but in your case, they accidentally sometimes bite down on your  lip. The degree of “overjet”, that is the horizontal gap between the upper and lower front  incisor teeth may play a role. In an ideal bite the upper and lower jaw close and the incisors gently touch and glide past one another, much like the blades if a pair of scissors. The upper incisors come down and over the lower incisors, covering them like a roof shingle overlapping the shingle beneath it.

The degree of coverage is ideally is about 10 – 20% of the vertical length of the lower incisor. Beyond this range, the bite relationship begins to transgress onto a condition known as a deep anterior vertical overbite. This is a vertical manifestation not to be confused with the horizontal relationship I described earlier and designated as an “overjet”. Remember “overbite” is vertical; “overjet” is horizontal. In some people, the horizontal upper and lower front incisors may not be so ideal.

A person who when biting down has a 3-5 mm horizontal gap between the upper and lower front teeth, may have a similar or even larger horizontal space when they slightly open their mouth. In dentistry this is sometimes called the “rest position” vs. the “centric occlusion” position when a person bites down. The field of “occlusion” ( bite relationship of the teeth) is a complex one, and is beyond the scope of this reply. The main point I wish to make is simply that if a person has a slight horizontal gap or overjet, the lower lip may also have a passive position whereby it closely rests against the outside surfaces of the lower teeth. So, when chewing food or sometimes just biting down on the teeth, a person with a dental  overjet and a relatively mobile lower lip may experience the biting problem you describe.

Now, having said that, I have also had orthodontics myself, do not have a horizontal gap at all among my upper and lower incisor teeth, yet on occasion bite down on my lip as well. In my case I simply have come to the conclusion that it just happens to be the way I apparently move my lips when chewing.  There is a muscle called the orbicularis oris which surrounds the mouth and it has a great deal of influence on the lips. Practically speaking there is nothing I am able to do to prevent the occasional mashing down on my lips when eating.

Kenneth, there have been occasion when NOT eating that I have bitten down on my lip. In this situation there is one remedy which I have personally found to be helpful. I have a lower clear retainer which I wear to help keep my teeth in alignment. I will be wearing this long term.  I have never bitten my lip while wearing the retainer. I believe it functions, in part, to reflect the lower lip a little away from the teeth and therefore the edges of the incisors when they meet.  I also believe that the retainer obviously keeps the teeth from fully biting down, because my lower clear retainer covers all the lower teeth back to and including the second molars.  By so doing, it prevents the incisors from completely occluding or touching. I suppose if I purposely attempted to curl my lower lip inwards while biting down I could manage to bite down on my lower lip, but it would take an effort.

Some patients I know have a dysfunctional lip habit during which they curl their lower lip in one direction or another. These patients have a nervous habit of licking or gently biting down with their upper teeth onto their lower lip. Breaking such a nervous pattern can be difficult, and again a lower clear retainer may be of help.

So Kenneth, what is the bottom line.

1)   Ask yourself if you have a habit of pursing, licking, or biting your lower lip, and if so what you can do to modify this pattern.
2)   Consider asking your dentist to fabricate a thin clear lower retainer for your lower teeth. It should span from the lower left to the lower right farthest rear molar thereby covering all the teeth.
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3)   If lip dryness is causing you to lick your lips consider a lip balm or ointment such as Blistex to relieve the problem.

Ken, thank you for writing on a question that actually strikes personally to home.  Also for readers, again please allow 7 days for a reply, because I often consult with other colleagues about many of the questions I receive. By waiting you get the benefit of several professionals chiming in via my responses. In your case Ken, I also asked a Dermatologist, and two Family Dentists.  

Ken, I would appreciate a follow up note to see if using a retainer has helped. Please stay in touch and let me know how all this works out.

Paul Supan, DDS, MA, MPH
Board Certified Orthodontist

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

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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.

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Available upon Request.

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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.

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

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