endo sheet # 6-SAJA AL-3jarmah

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Mandibular molars
"Root anatomy and access cavity"
This sheet will contain the doc comments about what previously written in the handout so plz refer to it while studying.. 
Note: talking about the lab, the drop- in issue will be managed as we work on molars so don’t panic 
*First lower molar: in addition 2 the handout
- we said that it has 2 roots ;mesial and distal,and 3-4 canals . MB and ML in the mesial root and( DB and DL) in the distal root.
* Mesial root has 2 walls ; mesial and distal .
- distal wall is thin and concave one , which has a thin cementum and dentine that means the canal is not located in the bulk of the root it is more distally ; so while working on this tooth don’t take from the distal wall as much u take from the mesial wall cause this will lead to a perforation .
- Number of canals in the mesial root: refer 2 the percentages and memorize them well 
Important exam questions :
*according to vertucci ,what is the percentage 2 find 2 orifices in the mesial root of the lower first ?
-- pay attention to ()
59% -8%=51%+28%= 79%
59% : is the percentage to find 2 canals
8% : is the percentage to find one orifice which will divide later on 2 give 2 canals ; so that we do the omission thing .
28% : is the percentage to find 2 orifices that will end up in one canal later

*according to Gulabivala , what is the percentage to find 2 orifices ?
50% - 6%=44%+29%= 73%
50% : is the percentage to find 2 canals_2 orifices_
6% : is the percentage to find one orifice which will divide later on 2 give 2 canals
29% : the percentage to find 2 orifices that will end up in one canal later

** if we are working on a tooth that has 2 orifices which will join later 2 form one canal ; we do cleaning and shaping and obtain a certain work length then placing the restoration , on the later procedure we will notice that while doing the first orifice we are dealing with the work length that we have previously obtained but then ,working on the second orifice , we will find a shorter work length or a blockage that is an indication that we are working on one canal that formed by joining of 2 orifices .
-Note : blockage maybe due to other factors .

**Access cavity of the lower first is close to the upper one .
-note: choose ur burs according to whatever u see appropriate .
p.8(in the handout) pictures:
1) we can see 2 mesial orifices and one oval distal orifice.
2) access cavity procedure : a) diamond round bur perpendicular 2 the occlusal table ,,directed toward the largest canal ,distal canal until drop-in felt .
b) un roofing using a round bur to remove enamel and dentine .
c) smoothening of the walls and finishing carried by fissure bur .

p.9 :
first two pictures we can see 5 canals ,2 distal ( DB,DL) and 3 mesial ( MB,ML,MM)
MM:middle or minor mesial (1-15%)

*Lower second molar
Note: the two mesial canals are closer to each other than that of the lower first so don’t go away far laterally .
*Number of the canal on the distal root:
*-according to vertucci what is the percentage to find a single orifice?
(95%+1%)-3%= 93%

*P.12 pic:
Rectangular in shape access cavity , because we have 2 orifices each one is oval in shape not round so we will obtain rectangular shape.

*Lower third molar
As the upper third molar ,,needs careful examination of root morphology before treatment is essential .

**Teeth with C-shaped root canal system:
We will find a single ribbon-shaped orifice instead of finding a certain number of orifices.
-the filling is the hardest part while dealing with such teeth so u have 2 recommend a specialist for ur patient 
Good luck
Corrections r welcomed
Sun 24-10-2010
SAJA AL-3jarmah