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Periodontics/Gum and bone loss in crown lengthening


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. Each time it came off it was recemented, but the last time on 24/12/2014 it was swallowed by mistake while eating.

This molar is very very short, only ~ 1 mm above the gum line. I have been thinking about having crown lengthening surgery before installing a new crown. I saw a periodontist and he said that he would have to remove 5 mm depth of (gum + bone) surrounding this tooth in this surgery. Without using any special instrument, I estimate that my lower jaw bone beneath this molar is about 1 inch (25 mm) high only.  

Is it common to remove 5 mm+ this much depth of (gum + bone) in crown lengthening to help restore a very short tooth ? This sounds like too much and terrifying to me.

What are the consequences of removing 5 mm+ of (gum + bone) ? Will the tooth be loosened ? Will the roots be exposed and difficult to clean and cause problems before the new crown is installed ? Will the adjacent tooth/teeth be affected (e.g. tooth loosened ? gum recession ?) Will the lower jaw be affected ? I think the new gum line of this tooth will be much lower than the gum line of the other teeth. Will there be  problems in occlusion and eating ?

Dorothy, you are asking some very good questions.  In the area you are describing, 5mm of bone is quite a lot.  If I could see a film I could give you a better assessment of whether or not doing a crown lengthening is a good idea.  Taking bone away will certainly have an impact on the surrounding teeth.  Given what you are describing there may be more wisdom in removing the tooth and replacing it with an implant.  Again, if I could see a x ray that would really help.

Good Luck
Dr. Siegelman


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Bryan M. Siegelman, DDS


I can answer any question relating to the diagnosis and treatment of periodontal disease. I can also answer questions relating to the placement and restoration of dental implants.


I have been practicing Perioodontics for the past 20 years. I limit my practice to periodontics and implant dentistry. I am a diplomate of the American Academy of Periodontology. I am in private practice in Pennsylvania and am on staff at the local hospital in my home town. My practice website is

American Academy of Periodontology, Academy of Osseointegration, American Dental Association, American College of Dentists, Pennsylvania Dental Association

I have a BS from Muhlenberg College, I did a general practice residency at St. Joeseph's Hospital and Medical Center in Paterson, NJ. I received my DDS degree and specialty certificate from the University of Maryland Dental School.

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