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Periodontics/Rear Molar too short. Crown keeps coming off.


QUESTION: My lower L. molar at the back (#7) was badly damaged, had root canal treatment and filling and was then fitted with a crown in 2009. In 2012 this crown started to come off very often. My dentist said that my molar (height above gum line) was very short. Each time this crown came off it was recemented, but the last time on 24/12/2014 it disappeared while I was eating (I must have swallowed it by mistake). There is no LL tooth #8, and LL tooth #6 has a crown and has had no problem. Now, I am not using this molar (#7), and am using the teeth on the right side (LR tooth #6 missing) for eating.  

What options do I have ? Is crown lengthening on this LL molar (#7) viable ? Prognosis ? What are the risks ? Will crown lengthening loosen this molar and make it unable to perform its chewing function ? Will the exposed roots be difficult to clean and cause problems ? Will adjacent teeth be affected ? In case crown lengthening fails, is it not possible to insert an implant later ? Is forced extrusion viable and what are the risks ?

ANSWER: Unfortunately it is not possible for me to judge the prognosis of your last lower left molar without seeing x-rays and the situation in your mouth.

Whether crown lengthening is an option depends on many different things. The main issue is how the border of the bone is related to the point where the two roots of the tooth separate from each other (the furcation area). The bone level of the adjacent tooth (the first molar) also is an important factor. Other factors include the health of the remaining tooth, the shape and health of the gum tissue, how the inner structures of the cheek relate to the tooth, how well you are able to clean the tooth, what your overall periodontal situations is like, etc.

In my opinion, crown lengthening should not be done unless all these criteria are met.

If all these issues are fine, the crown lengthening is done properly, and after this a well-fitted, technically faultless crown is made, then the prognosis will be good. If this is the case, there are no risks, the tooth is not loosened by the procedure, you are able to clean the tooth and adjacent teeth are not affected.

Crown lengthening might fail if all the listed criteria are not taken into consideration. Then it is possible to insert an implant later.

Forced extrusion is a far more complicated and uncertain procedure and I do not recommend it since the tooth has two roots and is the last one in the row.

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

QUESTION: Thank you so much for a prompt reply. Sorry about my delay in responding.

I read on the internet that "removing bone from around a tooth can make it feel looser". What does this mean if the crown lengthening procedure does not loosen a tooth ? Is this a feeling that a person has after crown lengthening for the rest of his life ?Does one get this feeling with or without his tongue touching the crown-lengthened tooth ?  Does this feeling make a person uncomfortable ?

The healing of bone always makes it temporarily softer. Therefore, a tooth can feel looser after any kind of periodontal surgery. This is temporary and goes away as the bone heals.

Feelings are a very personal issue. Some people feel the slightest differences happening in the mouth, other people may have teeth pulled without much trouble. Some people feel uncomfortable very easily, other people feel good most of the time. I cannot guess what kind of person you might be and how much uncomfortable you might feel. In any case, when the wound and the bone heals, you will most probably get used to the new situation.


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Marketta Hormia, DDS, PhD


I am a periodontist living and working in Helsinki, the capital of Finland, where I have my private dental practice. I am an international member of the American Academy of Periodontology. I have a Ph.D degree and a long background in research and teaching at the University of Helsinki and at the University of Turku, Finland. I function as an adjunct Professor at these Universities. I have also worked as a visiting scientist at the Scripps Clinic and research Foundation, la Jolla, CA. I can answer any question in the fields of dentistry and periodontics.


Private practitioner in Helsinki, Finland over 20 years. Former researcher and teacher at two Finnish Universities.

The Finnish Society of Dentists, Division of Periodontology, American academy of Periodontology

Over 30 scientific research articles published in peer-reviewed international scientific journals (can be found on PubMed)

D.D.S., Ph.D, Specialist in Periodontology. Adjunct Professor.

Awards and Honors
Visiting Scientist at the Scripps Research Foundation, San Diego, California, 1992-1994. NIH grant

Past/Present Clients
Dental patients, national and international. All kinds of dental, oral and temporomandibular joint problems

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