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Dentistry/hyper protrusion of root canal molar

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Question
I had a root canal in my last lower right molar several years ago. Last November 2014 I had a gum boil cyst under that same tooth, but no pain. After the boil went away I noticed my tooth started to hyper protrude enough to throw my bite off of course. My dentist is at a loss so sent me to endo doc who felt the root canal was well done and couldn't figure out why this tooth is starting to protrude... in an effort to save the tooth we grinded it down to correct my bite.  Which lasted about 3 months before it protruded more and we had to grind it again. I have no pain or sign of gum disease or decay.

Do you have any idea what could be causing this ?? I have no pain or signs of infection and the boil hasn't returned.

Answer
Dear Mimi,
I am glad you have followed up with your question concerning your protrusion issue. Of course without a thorough clinical and new radiographic examination, it is difficult to fully diagnose your problem. However, based on your history  I am going to provide my detailed thoughts.

You still have infection in the bone as evidenced by the "gum boil" that has drained. This absolutely needs to be investigated further. When a "Gum Boil" appears, it is a sign of the opening of a pathway from an infected area in the bone around your tooth through the gum. It is called a fistula or in the upper jaw (maxillary jaw) a sinus tract.This is your bodies way of trying to drain out the pus and infection that has built up in the bone. It can be a sign of a root canal failure to heal, periodontal(gum) disease,or drainage from a micro crack on one of the roots.
When a "Gum Boil" appears, the opening can sometimes be tracked by the clinician inserting a piece of gutta percha (a thin piece of rubber root canal filling material). Many times a routine periapical xray can then identify the exact location of the infection and pathway of drainage from the tooth. However, once the "Gum Boil" heals over as it did in your case, tracking it is not possible, until it reappears. Many times it will again build up pressure, maybe even swell and then pop open and drain. When the pressure continues to build up, the tooth is pushed up in the socket and hyper protrudes. (This is what has happened in your case)
The correct treatment was to go to an endodontist and evaluate the root canal. However, since you have continued to have hyper protrusion of the tooth, this indicates an ongoing infection that has continued to develop around your tooth,and is raising the tooth up in the socket.This is why you continue to (occlude) bite on it. Therefore, the underlying cause needs to be identified and treated.
The best way to identify this problem is radiographically. You had this done previously and nothing was found.
Unfortunately, the standard 2 dimensional periapical xray is not always able to identify recurrent inflammation or bone infection especially in the posterior molar area.

Scientific documentation of this can be read on the internet by reading the Bender and Seltzer articles on Radiographic Interpretations of Intraboney Lesions published in the Journals of Oral Surgery, Oral Medicine and Oral Pathology and the J. of Endodontics. Basically they state that an infection can be very large in the posterior mandible (lower jaw) in the Cancellous Bone(soft bone), and because it doesn't penetrate the Cortical Plate (the hard bone which you can feel by pressing your fingers on either side of the bone around your molar teeth)it will  NOT be readily observed on routine dental periapical xrays(the type you had). If the infection doesn't penetrate this junction between the soft and hard bone it will be missed on xray even though a problem exists. The authors have even shown that a bone lesion the size of a golf ball will not be observed on routine 2 dimensional xrays.

Thus the correct treatment for you is to have a Cone Beam CT Scan which is a three dimensional radiographic evaluation of this molar tooth. This will identify the nature of your problem. Perhaps the root canal needs retreatment, or may need to have periapical surgery to solve your condition. Also, if you have a periodontal condition with this tooth, that will need to be addressed. CBCT Scans can also identify unusual root anatomy,additional canals, microcracks etc. These can all be evaluated before retreatment procedures are initiated.
I would suggest you contact a local dental school which has CBCT Scans, many Oral Surgeons, Periodontists and some Endodontist have these machines. However, the important consideration is not only obtaining a CBCT Scan, but having the xray read correctly. Many schools have American Board Certified Oral Maxillo-Facial Radiologists that routinely do this.
Good luck with your follow up, and hopefully you will be able to fully identify your condition and obtain proper treatment.  

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robert block

Expertise

I would prefer to answer questions related in my specialty of Endodontics( ROOT CANAL THERAPY) I am a Board Certified Endodontist with a special interest in advanced surgical endodontic procedures. I know root canals create a lot of apprehension in patients, and they usually have many questions about the procedure. I can address patient concerns either before or after their root canal treatment. I also have re-treated numerous patients who have had previous endodontic treatment. As a result of these clinical failures,and the increase in the use of dental implants, its important patients understand the alternatives of therapy. There are often many components to treatment that interrelate the disciplines of endodontics, periodontics and restorative dentistry.Patients frequently question the importance of considering all facets in a clinical regimen. Hopefully, I would be able to educate and contribute some information from the endodontic perspective.

Experience

Diplomate American Board of Endodontics, 35 years plus private practice experience. Formerly Professor and Chairman, Department of Endodontics at US dental school. Editorial journal reviewer for the endodontic section of The Journal of American Dental Association. Serve as a reviewer on several editorial boards.

Organizations
American Association of Endodontists, College of Diplomates, American Board of Endodontics

Publications
Over 150 publications, abstracts, case reports, chapters in textbooks. J. Dental Research, J. of Endodontics, J. of Oral Surgery Oral Medicine Oral Pathology,The NEXTDDS J.For example: The Single File Approach for Predictable Endodontic Canal Instrumentation:The Wave One, THE NEXTDDS J. 4-2:13-17 Fall 2014 Non Surgical Management of an Endodontic Failure Utilizing Contemporary Technology, www.THENEXTDDS 5-1:60-63 Spring 2015 Are You Still Using Formocresol? An Update, Tn. Dent. J. 89-4:14-19 Fall 2009 Management of Endodontic Failures, Oral Surg.vol.66:711-Dec.1988

Education/Credentials
BA. DePauw University, DDS. University of Michigan, MS. Medical College of Virginia, Virginia Commonwealth University, Gen. Practice Resident, University of Connecticut, Endodontic Resident Medical College of Virginia, Virginia Commonwealth University

Awards and Honors
Numerous Awards and Honors, Edward P. Hatton Award( Int. Assoc. of Dental Research), Endodontic Memorial Research Award ( American Association of Endodontics) Outstanding Endodontic Department Teaching Award (given by dental students)Fellow American Academy of Dental Science

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