Endodontics (including DM) Flashcards
Roots and canals: maxillary first molar
4 canals (93% JOE 1999) – TWO MB canals.
Roots and canals: Maxillary second molar 56.9%
3 roots, 3 canals
Roots and canals: Maxillary second molar 22.7%
3 roots, 4 canals
Roots and canals: Maxillary second molar 9%
3 roots, 3 canals ( initially but MB and DB combine)
Roots and canals: Maxillary second molar 6.9%
2 roots, 2 canals
Roots and canals: Maxillary second molar 3.1%
1 root, 1 canal
Roots and canals: Maxillary second molar 1.4%
4 roots, 4 canals (2 sit palatally)
Roots and canals: Mandibular first molar - distal root 70%
70% = 1 canal
Roots and canals: Mandibular first molar - distal root 15%
15% = 2 canals (joining)
Roots and canals: Mandibular first molar - distal root 5%
5% = 2 canals
Roots and canals: Mandibular first molar - mesial root 59%
59% = 2 canals
Roots and canals: Mandibular first molar - mesial root 28%
28% =2 canals (joining with single foramen)
Roots and canals: Mandibular first molar - mesial root 12%
12% = 1 canal
Roots and canals: Mandibular first molar - mesial root 1%
1% = 3 canals
Roots and canals: Mandibular second molar - mesial root 38%
38% = 2 canals (joining)
Roots and canals: Mandibular second molar - mesial root 35%
35% = 2 canals
Roots and canals: Mandibular second molar - mesial root 27%
27% = 1 canal
Roots and canals: Mandibular second molar - distal root 92%
92% = 1 canal
Roots and canals: Mandibular second molar - distal root 5%
5% = 2 canals
Roots and canals: Mandibular second molar - distal root 3%
3% = 2 canals (joining)
How many failed RCTs are as a result of missed canals?
42%
Upper premolars number of canals?
Usually has 2 but can sometimes have 3
Maxillary first molar roots
Maxillary second molar roots
Maxillary premolars roots
Mandibular first molars roots
Mandibular premolar roots
Infection: primary endo/secondary perio lesion
Infection: primary perio/secondary endo lesion
Infection: true combined lesion
Distance from buccal cusp to roof of pulp chamber?
6mm
Height of pulp chamber
Distance from plural floor to furcation
Accessory canals in first mandibular molars: 23%?
23% have a lateral canal from the coronal third of a major root canal to the furcation region
Accessory canals in first mandibular molars: 13%?
13% have a single furcation canal extends from the pulp chamber to the intraradicular region
Accessory canals in first mandibular molars: 10%?
10% have both lateral and furcation canals
REMEMBER? Accessory canals in first mandibular molars
Side, middle, double
Ferrule effect
o we WANT the ferrule effect
o 1.5-2mm of dentine
o “tube” of dentine
o Supportive help tooth bear occlusal load
Posts?
Not desirable (only for when there is barely any tooth left)
Success % of RCTs if the obturation is within the normal 0-2mm area
94%
Success % of RCTs if the obturation is too short
68%
Success % of RCTs if the obturation is too long
76%
Hulsmann criteria
For irrigant extrusion - HULSM acronym!
H - haemorrhage
U - undeniable symptoms (acute pain, swelling, redness)
L - loss of sensation (numbness, weakness of facial nerve)
S - secondary infection, sinusitis, cellulitis
M - massive face (swelling) infraorbital region or mouth angle
Antibiotics dosage: amoxicillin
500mg x 3 (for 5 days)
Antibiotics dosage: penoxymethylpenicillin
1 x 250mg 4 times daily (increase to 500mg for severe infections) – 5 days
Antibiotics dosage: metronidazole
1 x 400mg capsules 3 times daily – 5 days
Traditionally used sealers in RCTs
Calcium hydroxide materials
Zinc oxide eugenol materials
Glass ionomer cements
New advancements in sealers in RCTs
Bioactive calcium silicate cement Mineral Trioxide Aggregate (MTA) - are being favoured now e.g. biodentine due to their biocompatibility and they don’t shrink on setting, they also utilise the moisture in the canal by being hydrophilic - this helps them set.
Pain immediately after RCT not to worry about?
toxicity of some sealers on setting
Assessing success of obturation? COVP
C - coronal restoration adequate
O - obturation within 2mm of apex
V - voids absent
P - periapical lesion absent
What type of seal is necessary for a successful RCT?
Hermetic seal (Hermes could fly in the air) – sealed against the escape or entry of air.
Fluid tight or bacteria tight seal – more appropriate than hermetic seal as root canals are evaluated for leakage of fluid.
What situations could mean only 1 appointment needed for the RCT? ONE
o Only minor symptoms
o Not wet - blood/pus etc
o Everything goes (necrotic pulp/irreversible pulpitis etc)
What situations could mean only 1 appointment needed for the RCT? TWO
o Technically difficulties (anatomical complexities/patient or dentist is tired)
o Wet canal (persistent exudate in RC)
o Ouch – symptoms are acute
% composition GP cone
o 60 – zinc oxide
o 20 – gutta percha
o 10 – radioopacifiers
o 5 – plasticisers
o 5 - Other; waxes, colouring agents, antioxidants, and metallic salts.
Periapical diagnosis: Non TTP, no palpation findings
Normal radiographically
Normal periapical tissues
Periapical diagnosis: Tooth is TTP, +/- palpation findings
Loss of lamina dura, PDL widening radiographically
o Symptomatic periapical periodontitis (irreversible/necrotic pulp)
Periapical diagnosis: Non TTP, no palpation findings
Radiolucency around the apex of tooth radiographically
o Asymptomatic periapical periodontitis
Periapical diagnosis: VERY TTP, sinus/pus palpation findings
PDL maybe normal or slightly widened, distinct radiolucency where chronic lesion present.
* TREATMENT drainage!! Then RCT or extract.
Acute periapical abscess
Periapical diagnosis: Usually asymptomatic - Non TTP, sinus palpation findings
Radiolucent area on bone radiographically
o Chronic periapical abscess
Sodium hypochlorite
o antimicrobial
o can dissolve necrotic tissue
o No evidence suggests using NaOCl >1%.
o DDH we use 2%!!
o ~20ml of solution per canal.
o Disadvantages: unpleasant taste, highly toxic, inability to remove smear layer when used alone.
Management of Sodium hypochlorite extrusion
o Tell patient
o Help manage symptoms: analgesics, cold packs, antibiotics, refer to OS.
When irrigating where should your needle be bent?
- NEEDLE – place a bend 2-3mm short of the WL, to prevent going to far into the canal.
Citric acid function
- Citric acid (17% EDTA) – removal of smear layer
o Dissolves smear layer (particles are soluble in the acid).
Balanced force technique
- Balanced force technique – required for size 50 files diameter canals.
o Engaging: clockwise 60 degrees turn
o Cutting stroke: anticlockwise 120 degrees turn
o Removing: clockwise 60 degrees turn
Two ways a file can fracture in the canal
o Sheer/torsional fracture: an instrument will fail by torsion when the ultimate shear strength is exceeded – instrument has bound to the canal wall. Clinician’s fault.
o Flexural fracture/cyclical fatigue: instrument is subjected to tension and compression cycles at point of maximum flexure, continuous rotation in curved canals. Not clinicians fault.
Management of fractured endodontic instruments
o Locate (radiographically and by tactile sensation)
o Earlier is worse. Inadequate cleaning of area.
o Overcome (Bypass fractured instrument)
o Proceed? Consider symptoms and prognosis.
o Attempt removal? Is this feasible based on location.
o Radiolucency periradicularly = prognosis worse.
o Document and discuss with patient.
“LEOPARD”
Apical patency
the ability to pass a small Flexofile passively through the apical constriction without widening it (Buchanan 1989).
Micro/macro glide path
- MICRO glide path: established with hand instruments (size 08 and 10 k-files to WL)
- MACRO glide path: enhanced micro glide path with rotary instrument (Proglider)
Canal medication
Non-setting calcium hydroxide base (for inter-dental appointments) - anti-inflammatory.
Antibiotic/steriod paste for the canal
Odontopaste (zinc-oxide based).
Antimicrobial extra for the canal?
10min soak in Iodine-containing pastes
Bactericidal, fungicidal and virucidal and sporicidal.
Contra-indications: iodine hypersensitivity, pregnant and breast-feeding woman.
Crown Down Sequence
Crown Down Sequence – instrumentation technique for challenging anatomy:
o “Prepare from the crown all the way down”
o Focus on preparing the upper 1/3 of the canal and then work down to preparing the apical 1/3 of the canal.
o Prevents instrument binding or transportation during cleaning and shaping.
Pulp innervation fibres
90% A delta myelinated fibres, rest are A beta fibres and unmyelinated C fibres.
What material is better for direct pulp capping?
International endodontic journal 2021 = MTA (mineral trioxide aggregate) e.g. Biodentine are better for direct pulp capping than calcium hydroxide.
Reactionary dentinogenesis
Reactionary dentinogenesis: odontoblasts from pulp are recruited to lay down dentine as a result of a carious lesion.
Reparative dentinogenesis
Reparative dentinogenesis: pulp (odontoblast cells) is directly damaged and so odontoblast-like cell is used to make reparative dentine which is of poorer quality that the reactionary dentine.
Direct pulp capping classes
o Class I trauma or iatrogenic damage
o Class II infection
Pulpitis and the treatment you do for each
o Initial or mild pulpitis – indirect pulp capping
o Moderate pulpitis – coronal pulpotomy (partial/full)
o Severe pulpitis – coronal pulpotomy/RCT/Extraction
High risk of IE? VIC
o Valve prosthesis
o IE previously
o Congenital heart disease (cyanotic)
**some exclusions
Pulp becomes inflamed when bacteria is ___mm away
0.5mm
Clamp bow for maxillary teeth
facing down
Clamp bow for mandibular teeth
facing up
Partial pulpotomy = ___mm removed
2-3mm
Definition: Stress
Resistance force per unit area of a material against deformation when an external force is applied (mm2)
Definition: Tensile strength
Capacity of a material to withstand load trying to elongate the material.
Definition: yield strength
Stress the material can withstand without being deformed permanently.
Definiton: strain
o Change of original dimension when the material is under stress.
Defintion: elastic limit
o The greatest stress the elastic solid can withstand without being deformed permanently.
The elastic limit is the maximum stress that a material can undergo without experiencing permanent deformation. It is the highest stress a material can withstand and still return to its original shape when the applied stress is removed.
Definiton: plastic deformation
o Permanent deformation that pertains when the load is removed that exceeds a materials elastic limit.
Defintion: Plastic limit
o Breaking point of a material
Key properties of NiTi
o Super elasticity
o Shape memory
K files made from ?
Made from raw ss wire which is ground to 0.02 taper and shaped (triangle/square)
This is then twister in a COUNTER clockwise rotation to achieve the file.
Why is SS a good material in endo?
Stiffer than NiTi
Corrosion resistant (due to Cr and Ni)]
Memory shape
Memory shape means that you can heat the file to get it back to the curved shape it was once in (tailored to the canal).
High modulus of elasticity
A material with a high modulus of elasticity is stiff and resists deformation under applied stress.
It means the material requires a large amount of stress to produce a small amount of strain.
Examples of materials with high modulus of elasticity include metals like steel and ceramics.
Low Modulus of Elasticity:
A material with a low modulus of elasticity is more flexible and deforms easily under applied stress.
It means the material undergoes a significant amount of strain even with a relatively small amount of stress.
Examples of materials with low modulus of elasticity include rubber and some polymers.
