Week 1: Access and root canal location Flashcards
Which teeth fail the most following RCT?
- Upper first molars
- Lower incisors
- Lower canines
- Lower first premolars
- Lower first molars
- C shaped molars
Which canal is often missed in upper first molars
The second canal in the media buccal cusp (MB2)
So the end up only finding 3 not 4
Why might RCT usually fail in lower incisors?
As in 30-40% of them there’s lingual canal that is missed or can be inaccessible
Why might RCT in lower canines fail?
- Lingual canal is missed or inaccessible
2. The canals are usually longer and so it can be harder to prepare and obturate
Why might RCT in lower first premolars fail?
Difficult to locate lingual canal so can be missed
Why might RCT in lower first molars fail?
Distal roots usually can two canals and the second canal is usually missed
What is the average length of an upper first molar?
22mm
How many canals and roots are there in an upper first molar?
99% have 3 roots
Generally 4 canals
How many foramina are there in an upper first molar?
60% have 3
40% have 4
What is the average length of a lower incisors?
22mm
How many canals and roots are there in a lower incisor?
98% have 1 root
40% have 2 canals
Which canal is hardest to find in a lower incisor?
The 2nd lingual canal
How many foramina are there in a lower incisor?
90% have 1 foramen
10% have 2
What is the average length os a lower canine?
27.5mm
How may roots and canals are there in a lower canine?
95% have 1 root
Usually have 1 canal but 20% have 2
What is the average length of a lower first premolar?
23MM
How many roots and canals are there in a lower first premolar
80% have 1 root
75% have 1 canal, 24% have 2 canals and 1% has 3 canals
In a lower first premolar with 2 canals which canal is often missed?
The canal that is lingually placed
What is the average length of a lower first molar?
22mm
How may ROOTS are there in a lower first molar?
95% have 2 roots
5% have 3 roots
In the mesial root of a lower first molar how many CANALS are there?
12% have 1 canal
87% have 2 canals
1% have 3 canals
In the distal root of a lower first molar how many CANALS are there?
70% have 1 canal
30% have 2 canals
In the mesial root of a lower first molar how many FORAMINA are there?
60% have 2 foramina
In the distal root of a lower first molar how many FORAMINA are there?
85% have only 1 foramen
What are c shaped molars?
Single ribbon shaped canal with a 180 degree arc starting at messy lingual angle, sweeping around the buccal to end at the distastes aspect of the pulp chamber
Name the different laws we can use to help us find all the canals in a tooth
- Law of symmetry I
- Law of symmetry II
- Law of colour change
- Law of orificle location I
- Law of orificle location II
- Law of orificle location III
Which tooth is the only exception to both the law of symmetry?
Maxillary molars as their canals are halfway from a line drawing in a mesial distal direction through the pulp chamber floor
How do we use the law of symmetry 1 to ensure we have located all the canals?
We draw a line that bisects the tooth mesial to distal and we assume that any canal we find on one side we will find in the same place on the other side
How do we use the law of symmetry 2 to ensure we have located all the canals?
We draw a line that bisects the tooth mesio distally then perpendicular to this line we drawn another that separates the tooth bucco lingually
We assume that all teeth are symmetrically so if you find a canal in on one side of the tooth its mirror image will be there on the other side
All teeth are S________
Symmetrical!!!!!
What does the law of colour change state?
That the colour of the pulp chamber floor is always darker than the walls
State the law of orificle location I
The orificles of the root canals are always located at the junction of the walls and the floor
State the law of orificle location II
The orificles of the root canals are locates at the angles in the floor wall junction
State the law of orificle location III
The orificles of the root canals are located at the terminus of the rot developmental fusion lines
To be able to use the law of orificles III what must you have
Good magnification
How big should the access cavity be?
The base of the access cavity needs to be no bigger than the footprint of the pulp chamber
Why should we try and make the access cavity as conservative as possible (while still being able to see the entire pulp floor)
So that we can conserve dentine
