Endo Basics Review Flashcards
Which Weine class has one single canal with one foramen?
Type I
Which Weine class has two canals converging to one foramen?
Type II
Which Weine class has 2 canals and two foramina?
Type III
Which Weine class has one canal dividing into 2 canals with 2 separate foramina?
Type IV
Maxillary Central Incisor (# roots, # canals, chamber outline, average length)
1 root
1 canal
Triangular pulp, 3 horns
22.5mm
What is the key to remember with respect to the pulp chamber and the external tooth morphology?
The pulp chamber forms the tooth so the shape of the pulp chamber mimics the shape of the tooth
What is common in maxillary central incisors that must be removed to allow access to the lingual wall of the root cavity?
Lingual shoulder
What is the difference in root canal shape of a maxillary central incisor between a young tooth and an older tooth?
Young maxillary central incisors have a triangular-shaped pulp chamber wherease the older ones will have an oval shape
Maxillary Lateral Incisor (# roots, # canals, chamber outline, average length)
Single root
Single canal
Compressed triangle, 2 horns
22 mm
Maxillary Canine (# roots, # canals, chamber outline, average length)
Single root
Single canal
Oval pulp NO PULP HORNS
26.5mm
What is common about all anterior maxillary teeth?
Lingual shoulder must be removed
What is not evident radiographically on maxillary canines and what does it require?
Facial curvature of root apex; must do tactile exploration with small file prior to inserting larger files
What is the character of mandibular incisor root canal that splits into 2 canals, but exits foramen at one common foramen?
2 canals in 20-40%
Usually reunite and exit at 1 common foramen
What Weine class is a mandibular incisor root canal that splits into 2 canals, but exits foramen at one common foramen?
Type II
In a mandibular incisor with 2 root canals, where does the division of canals usually occur?
Coronal to the middle third
Where is a mandibular incisor pulp chamber and root canal wider: labiolingually or mesiodistally?
Labiolingual (opposite of maxillary incisors)
What is the access outline of mandibular incisor and what does it depend on?
Oval to triangular depending on the prominence of mesial and distal pulp horns
What is the average length of the mandibular incisor?
20.7 mm
What commonly covers the 2nd canal in a mandibular incisor?
Lingual shoulder
In what patient would you have a more triangular access due to more prominent mesial and distal pulp horns?
Younger
What is the clinic technique to ensure removing lingual shoulder to expose the common (20-40%) 2nd canal in a mandibular incisor?
Extend access prep well into cingulum gingivally
Mandibular canine characteristics (# roots, access outline, average length).
Smaller overall dimensions than maxillary canine
2 roots and 2 canals not uncommon
14% have 2 canals at orifice and 6% have 2 canals at apex
Oval access, wide BL, narrow MD
25.6 mm
Maxillary premolars have how many roots and which is most common?
1,2, or 3 roots
Common = 2 roots with 2 canals
Where are the pulp horns and where is the pulp chamber wider in a maxillary 1st premolar?
- BL pulp horns
2. Wider BL than MD
What is the external access form for a maxillary 1st premolar?
Oval, wide BL, narrow MD, centered between cusp tips
What is a morphologic consideration with a maxillary 1st premolar for the preparation?
Mesial root concavity, if you overextend mesially you could perforate the root
What are 2 places the maxillary 1st premolar is prone to fractures?
MD root fractures
Fractures at base of cusp, particularly buccal cusp
What is required restoratively after root canal therapy to prevent cuspal and/or crown/root fracture of a maxillary 1st premolar?
Full occlusal coverage to prevent cusp or crown/root fracture
What is present in the lingual aspect of the buccal root at the level of the furcation?
Prominent dentin depression
Maxillary 2nd premolar has how many roots most of the time?
One
What is the majority root canal morphology for a maxillary 2nd premolar?
75% 1 canal at apex
What is the 2nd most common root canal morphology for a maxillary 2nd premolar?
24% 2 canals at apex
The maxillary 2nd premolar has how many pulp horns and which is the larger of them?
B and L pulp horns, the buccal is larger
What is the access outline for maxillary 2nd premolars?
Oval, wider BL than MD
What is the average length of a maxillary 2nd premolar?
21.5 mm
What are 2 places where maxillary 2nd premolars are prone to fracture?
MD root fracture at the base of the cusp (particularly the buccal cusp)
What is required restoratively after endo treatment of maxillary 2nd premolars and why?
Full cusp coverage restoration to prevent cusp or crown / root fractures
What is the morphology of mandibular 1st premloar root canal systems?
2 pulp horns with large pointed B horn and small rounded lingual horn
The majority (74%) of mandibular 1st premolars have how many canals at the apex?
One
What is the second most common (24.5%) number of canals at the apex of a mandibular 1st premolar?
Two
What is the racial statistic in mandibular 1st premolars?
2 rooted mandibular 1st premolar 3 times higher incidence in African Americans
What is the average length of mandibular 1st premolars?
21.6mm
What is the character of the 2 canal mandibular 1st premolar?
Lingual canal diverges at sharp angle away from central canal. Fast break.
The crown morphology of a mandibular 1st premolar does what to files?
Lingual incline of crown deflects files buccally
The mandibular 2nd premolar normally has how many roots and how many root canals?
1 root, 1 canal (97.5%)
What is the racial statistic in mandibular 2nd premolars?
Three times higher incidence of 2 roote mandibular 2nd premolars in African Americans
What is the average length of mandibular 2nd premolars?
22.3mm
What is an opening created down the center of the tooth into the pulp chamber in order to enter the root canals space?
Endodontic access
Endodontic access openings are based on what?
Anatomy and morphology of individual tooth
What dictates the design of access cavity or preparation for endo?
Pulp chamber morphology
What determines the external surface of the tooth?
The internal pulp anatomy
What are 5 objective of endodontic access?
- Excavate caries
- Locate all canals
- Completely remove pulp chamber roof and all coronal pulp tissue
- Achieve straight line access
- Conserve tooth structure
When removing coronal pulp tissue during endodontic access, may vital tissue be left behind and only necrotic pulp tissue be remoed?
No. Remove ALL pulp tissue because remnants can harbor bacteria that can compromise success or discolor crown.
What causes crown discoloration after incomplete removal of coronal pulp tissue or even trauma to a tooth?
Build up of hemosiderin
Where does straight line access go?
Either to the apical foramen or to the initial curvature of the canal
What can commonly inhibit straight-line access with respect to the pulp chamber and access?
Lingual shoulder
What are 2 reasons why an endodontic access seeks to conserve tooth structure?
- Avoid weakening tooth
2. Maintain restorability
What are the requirements for endodontic access?
- Knowledge of tooth anatomy
- Clinical inspection of tooth
- Preop radiographs (PA, shift shot, BW)
When is a BW radiograph useful for endodontic treatment?
Visualize posterior teeth pulp chambers and their tilt/angulation
How is a BW good for determining restorability of a tooth prior to endodontic treatment?
Good indicator of bone levels, extent of caries or previous restorations
When must a rubber dam be placed?
Can be after access, but must be on before any file/instrument is placed into the canal space
What are the best burs to use for access?
Round #4 and Round #2
What bur is used once the pulp chamber is accessed and why?
Endo Z bur to go across chamber and make form without going deep, Z bur is a side cutting bur only
What is a Gates Glidden bur used for?
In a slow speed for opening coronal flare of canal space
What is an endodontic spoon excavator used for?
To remove pulp tissue and stones
What is an endodontic explorer used for?
To locate canals
For a maxillary central incisor, more prominent pulps horns means what?
The more triangular the access
What is the bur location and placement for initial access on maxillary incisors?
Perpendicular to the lingual surface in the middle 1/3 of the crown
What is the bur placement on a maxillary central incisor once the initial access outline is made?
Parallel to the long axis of the tooth
How do you unroof a chamber completely?
After penetrating the pulp chamber, catch the round bur under the lip of the dentin roof and remove un upstroke/withdrawal
What is a method to confirm complete roof removal?
Take the operative explorer and see if the tip catches when you withdraw it towards the occlusal on the M D and F walls
What is the term for the lingual shelf of dentin that extends from the cingulum to a point approximately 2mm apical to the orifice?
Lingual shoulder
What are 3 options for removing a lingual shelf?
Tapered diamond, carbide, gates glidden
What will occur if the lingual shoulder is not removed?
File deflected buccally and will not make contact with the lingual wall of the canal
A mandibular incisor access should be broad where?
FLwider, MD narrow
As a mandibular incisor pulp recedes, what does this do to the access outline?
Access becomes more ovoid while a younger patient with more prominent MD pulp horns will have a more triangular access outline
Mandibular incisors can have 2 canals what percentage of the time?
20-40%
What mandibular incisor character makes access difficult and perforation easy?
Narrow MD
MD concavities
Which canal will be easier to locate in a 2 canal mandibular incisor?
Facial. The lingual is covered by the lingual shoulder
What should you always do with the access prep on the mandibular incisor and why?
Extend towards the cingulum to look for the lingual canal
What bur is recommended for the lingual shelf removal on mandibular incisor and why?
Gates Glidden in slow speed because the crown is narrower MD
What can mandibular canines have that is uncommon in maxillary canines?
2 roots and 2 canals
Why is the canine access ovoid?
Absence of pulp horns
What is the crown morphology difference between a mandibular canine and maxillary canine?
Mandibular crown is longer and more slender than maxillary canine
How far should the incisal access of a canine be from the incisal edge to allow for streight line access?
2-3 mm from the incisal edge
What is a consideration in the access of mandibular canines?
2nd canal. Gingival extension penetrating cingulum to allow for exploration.
The BL access extension is normally wider on which tooth: Maxillary 1st premolar or Maxillary 2nd Premolar
Beneath B and L cusp tips equidistant from a line through MD of chamber
What is the position of the canals in a maxillary premolar?
Beneath B and L cusp tips equidistant from a line through MD of chamber
If 3 canals exist in a maxillary premolar, which root will most likely house the 2 canals?
Buccal
What is the outline access form and orientation for a maxillary premolar with 3 canals?
Triangular with the base at the facial (over B root) and the apex towards the lingual / palatl root
In a maxillary 1st premolar, where is the mesial concavity located?
At the level of the CEJ with thin tooth structure at mesial, causing a risk for lateral perforation
If the file deflects buccally or linguall in a maxillary 2nd premolar, what is this indicating?
There is a second canal, if not already located
If a large, centered, oivoid canal located in a maxillary 2nd premolar what does this indicate?
A single canal
Which mandibular premolar is prone to multiplpe canals?
Mandibular first premolar. Only the mandibular 2st premolar has the likelihood of 3 canals
What is an external orientation consideration for endo on a mandibular premolar?
Crown tilted lineally relative to root: mandibular 1st moreso than mand 2nd
Due to the lingual inclincation of the mandibular first premolar, where should the access prep be started?
Halfway up buccal cusp versus just buccal to central groove in mandibular 2nd premolar
What are the access laws?
- Law of Centrality
- Law of Concentricity
- 1st Law of Symmetry
- 2nd Law of Symmetry
- Law of Color Change
- 1st Law of Orifice Location
What does the law of centrality state?
Floor of pulp chambe ralways located in center of tooth at level of CEJ
What does the Law of Concentricity state?
Walls of pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ
The external root surface anatomy reflects what?
The internal pulp chamber anatomy (Law of Concentricity)
The first law of symmestry states what and what tooth is the exception?
Canal orifices line on a line perpendicular to a line drawn MD through the center of the pulp chamber floor EXCEPT MAXILLARY MOLARS
What does the Law of Color Change state?
The pulp chamber floor is always darker in color than the walls.
What does the 1st Law of Orifice Location state?
Orificies of root canals are always located at the junction of the floor and the walls
What are 4 errors in Access Cavity preparations?
- Failure to unroof pulp chamber
- Inforrect bur angulation during access
- Failure to measure estimated depth of access
- Incorrect tooth accessed
What is a problem resulting from failing to completely unroof a pulp chamber?
Leave the pulp horn and therefore leave the pulp tissue
What is a problem resulting from failing to correctly angle the bur during access?
- Miss the pulp chamber
2. Perforate tooth
What is a problem resulting from incorrectly measuring the estimated depth at access?
Extend beyond the pulpal floor and perforate
What is a method to avoid accessing the wrong tooth?
Always count and verify
