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  Cracked tooth

How Does the Pulpal Floor of a Molar Tooth Develop?
Shintaro Kondo1) and Hajime Hanamura1)
1) Department of Anatomy, School of Dentistry, Aichi-Gakuin University
(Received July 28, 2009)
(Accepted September 7, 2009)

Development of the pulpal floor was reviewed from both macroscopic and microscopic perspectives,
and relations between individual variation in tooth roots and their development are considered.
It has been thought that the pulpal floor of a molar tooth is formed as a continuation of the
coronal dentine in rodents. In humans, the interradicular dentine develops from a separate
mineralization center or centers (subpulpal lobe), and only later does it unite with the coronal
dentine. The subpulpal lobe appears in the tooth germ of some mammals other than humans,
but it is absent in mice. The molars of Suncus have a large pulpal floor, and are useful as a
model of the development of the bifurcation area. The calcified process of the pulpal floor in
Suncus is divided into two stages: (1) the primary subpulpal lobe appears, and (2) a secondary
subpulpal lobe forms aggregated by the small calcified centers. The number of secondary subpulpal
lobes determines the root number. The connecting line among the subpulpal lobes on the completed
tooth becomes a ridge (interradicular crista) on the external surface, and a groove (isthmus)
on the internal surface. The pattern of the interradicular crista seems to depend on the number
of roots. We addressed the following three macroscopic variants and these developments;
(1) three-rooted mandibular molar, (2)enamel projection, and (3) gutter-shaped root.
These structures relate to developmental events.

Key words
pulpal floor/ subpulpal lobe/ interradicular crista/ multi-rooted tooth/ gutter-shaped root
The opinions within this web page are not ours. Authors have been credited
for the individual posts where they are. - photographs courtesy: Mark , John A Khadamy

From: Mark Dreyer
Sent: Monday, August 07, 2006 11:59 PM
Subject: [roots] Crack

First case of the day.  Crack stopped shy of the pulpal floor, 
so we went for it. - Mark

cracked tooth

Hi Mark, This is a cracked tooth I have been treating for almost 6 months now.  
After listening to Carr, Schwartz and other pretty smart guys, I am taking a more 
cautious approach to these cases.   I think given the predictability of dental 
implants, especially in the posterior mandible, we need to leave no stone
unturned in these cracked tooth cases.

cracked tooth

The pics show the fracture, which is a bit of an odd one, running down the lingual 
surface of the tooth to the ML canal. I have been staring at this thing every month 
since February (preop) and nothing has changed. There was never a probing defect 
in this tooth.  He has been symptom free for over five months.  While this
is no guarantee of success, we did due diligence and then some.  Pic4 is 1 month, 
pic5 is 4 months with evidence of healing, and pic6 is the final from today.

We finished the case today without anesthetic at the patients request.  You can 
grumble about the mesials being short, but they are actually about .25mm long.  
He could feel them just a little bit when I was fitting cones.  There were three 
distals, with two of them merging.  I thought there was an MM initially, but after 
troughing (pic3)--nothing.  The tooth was restored with a bonded amalgam, and 
remains out of occlusion.  We recommended a crown ASAP, and my recommendation 
would be for full coverage gold. - John A Khademy

Are you still using that intraoral camera thing for your photos? if so, which one are you using? Those are great shots, and i need something for my 2nd office. - Gary Hi Gary, I am using both the intraoral camera, and a Sony DCR-PC100 (DV camera) with a memory stick on the scope. The images are low resolution compared to Carlos' and others', but in print form you can't tell. The intraoral camera is cheap and really easy to use and give that "fisheyed" view of the whole chamber as opposed to the "confusing to some" mirror shots required by a scope mounted cam. The above pics are intraoral camera pics. - John A Khademy What beautiful dentistry !!!!!!! I am sure you used a bonded temporary, adjusted the tooth out of occlusion, and told the patient not to bite on it. The patient could be offered a gold crown or temporary Plastic crown from the beginning. - Dr. Danny O'Keefe
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