Endodontics Flashcards
Describe the infection involved in RCT
Pulp necrosis leading to the colonisation of the root canal system by bacteria, causing infection and bone resorption in the apical region.
Name contraindications for RCT
Insufficient periodontal support
Non-restorable teeth
Vertical root fracture
Poor condition of remaining teeth
At what point does a tooth have insufficient periodontal support for RCT?
Minimal bone support and grade III mobility
How does a tooth qualify as non-restorable and insufficient for RCT?
Extensive caries, root caries, massive resorptive defects, poor crown/root ratio
How does a tooth classify as non-strategic and a contraindication for RCT? short answer
No current or possible future function
What are some patient related potential RCT contraindications?
Age
Physical limitations
Patient financial status
Patient motivation and availability
How does age affect RCT complications?
Young patients - immature roots
Old patients - shallow pulp chambers, narrow root canals and systemic medical conditions
Name some abnormal canal configurations that are tooth related complications for RCT
Tortuous canals
Dens invaginatus
Severely curved canals
C-shaped canals
Taurodontism
Lingual developed groove
Abberant extra canals
What are tortuous canals?
Twisted, lengthy canals
What is dens invaginatus?
Developmental malformation in which there is an infolding of enamel into dentine
What is taurodontism?
Developmental disturbance of a tooth in which body is enlarged at the expense of the roots. Enlarged pulp chamber, apical displacement of pulpal floor and lack of constriction at CEJ.
What is internal root resorption?
Resorption that starts from the root canal and destroys the surrounding tooth structure.
What is external resorption and what can it occur in the aftermath of?
When the body’s own immune system dissolves the tooth root structure. Can occur following tooth infection, ortho or in presence of unerupted teeth.
What is hypercalcification?
Calcification of the chamber obscures the internal anatomy, can result in errors during preparation, can be caused by age or chronic inflammation/trauma
What crown to root ratio makes a tooth more susceptible to eccentric occlusal forces?
That exceeding 1:1
What is a general rule of thumb for Endo-perio lesions?
If it is more perio-heavy the tooth may still be vital but if it is more Endo-heavy the tooth may not be vital
Define a vital tooth
A tooth with a living pulp
Define a non-vital tooth
Tooth that has no access to blood flow, essentially dead
What are the three levels of difficulty on the AAE Endo case difficulty assessment form?
Minimal, moderate or high difficulty
Name three dentist related RCT contraindications
Lack of knowledge and/or skills
Lack of devices and technology
Lack of time
Name some medically related complications to treatment
Cardiac disease - risk of IE
Bleeding disorders
Diabetes mellitus
Cancer treatment
Pregnancy
Is RCT classed as a bleeding risk?
Endo - ortho grade is unlikely to cause bleeding.
Periradicular surgery is high risk of post-operative bleeding complications
Important if carrying out SURGICAL Endo procedure
What is INR?
International normalised ratio
What INR level is unsafe for any procedure?
> 4.0
When should a patients INR be checked before a minor dental surgical procedure?
Ideally within 24hrs (for a patient with a stable INR 72hrs is acceptable)
At what INR level should a patient continue warfarin therapy without adjustment before treatment?
If the result is under 4.0 you should continue warfarin therapy
If the INR is <4.0 and the patient has other conditions the patient should be referred to special care department - what are the other conditions?
Liver impairment / alcoholism
Renal failure
Thrombocytopenia
Haemophilia
Taking cytotoxic medications
What are safe pain relief for a patient on warfarin?
Paracetamol or Dihydrocodeine
What are safe antibiotics for patients on warfarin?
Amoxicillin or clindamycin
What is thrombocytopenia?
Condition that occurs when the platelet count in the blood is too low, therefore, slower blood clotting. Bleeding risk
What is haemophilia?
Usually inherited bleeding disorder in which the blood does not clot properly.
What are cytotoxic medications?
Medications that kill cells, including cancer cells
What is a risk of patients on antiplatelet medication?
May have prolonged bleeding time
Should patients on antiplatelet drugs be advised to stop their medication before RCT?
No
What is a safe pain relief drug for a patient on antiplatelet medication?
Paracetamol
Describe the bone in MRONJ
Exposed, necrotic bone in the maxilla or mandible that has persisted >8 weeks following surgical procedure in a patient taking anti-resorptive and anti-angiogenic drugs
What are anti-angiogenic drugs?
A drug or substance that keeps new blood vessels from forming
What is the estimated incidence of MRONJ in cancer patients on anti-resorptive or anti-angiogenic drugs?
1% (1 in 100)
What is the estimated incidence of MRONJ in osteoporosis patients treated with anti-resorptive drugs?
0.01-0.1% (1-10 cases per 10,000)
What drugs are associated with MRONJ?
Bisphosphonates
RANKL inhibitor
Anti-angiogenic
Name some bisphosphonate drugs
Alendronic acid
Zoledronic acid
Risedronate sodium
Sodium clodronate
Name a RANKL inhibitor
Denosumab
Name an anti-angiogenic drug
Bevacizumab
Sunitinib
Aflibercept
What is a RANKL inhibitor?
Blocks interaction between RANKL and RANK thereby inhibiting the formation of osteoclasts and enhancing bone strength
Denosumab
How is Denosumab administered?
60mg every 6 months but subcutaneous injection in upper arm, upper thigh or abdomen
Where do bisphosphonates accumulate and what can this cause?
Accumulate at sites with high bone turnover I.e. jaws
This may reduce bone turnover and bone blood supply leading to MRONJ
What is Denosumab and what does it do?
A human antibody that inhibits osteoclastic function by inhibiting RANKL.
What patients taking medication are at low risk of MRONJ?
Osteoporosis patients or other non-malignant diseases of bone (Paget’s disease) with bisphosphonates for <5yrs that are NOT currently being treated with systemic glucocorticoids.
Treatment for osteoporosis or other non-malignant disease of bone with quarterly or yearly infusions of IV bisphosphonates for <5yrs who are not concurrently being treated with systemic glucocorticoids.
Patients treated for osteoporosis or other non-malignant disease of bone with Denosumab NOT being treated with systemic glucocorticoids
What drugs and time scales put a patient at higher risk of MRONJ?
Patients treated for osteoporosis or non-malignant disease of bone with oral bisphosphonates or quarterly/yearly infusions of IV bisphosphonates for >5yrs.
Treated for OP or non-m disease of bone with bisphosphonates or Denosumab for any length of time who are being concurrently treated with systemic glucocorticoids.
Patients being treated with anti-resorptive or anti-angiogenic drugs (or both) as part of management of cancer.
Patients with previous diagnosis of MRONJ
Is antibiotic prophylaxis recommended?
Not recommended routinely for patients undergoing dental procedures
When it is indicated it is necessary ONLY FOR INVASIVE PROCEDURES
When would antibiotic prophylaxis be indicated?
Only for invasive procedures
What is antibiotic prophylaxis?
Antibiotics to prevent infection, given as a precaution rather than to treat infection
Is placing a matrix band classed as an invasive dental procedure?
Yes
Is placing a subgingival rubber dam clamp an invasive dental procedure?
Yes
Is placing a subgingival restoration including fixed prosthodontics an invasive dental procedure?
Yes
Is Endodontic treatment before an apical stop recognised an invasive procedure?
Yes
Is placing a preformed metal crown an invasive dental procedure?
Yes
Is a full periodontal examination an invasive procedure?
Yes
Is root surface instrumentation/subgingival scaling an invasive procedure?
Yes
Is an infiltration or block local anaesthetic into non-infected soft tissues an invasive procedure?
No
Is a BPE a non-invasive dental procedure?
No
Is a supra-gingival scale and polish a non-invasive procedure?
No
Is placement of supra-gingival orthodontic bands and separators an invasive procedure?
No
Is removal of sutures an invasive procedure?
No
Are radiographs an invasive procedure?
No
Is the placement or adjustment of orthodontic or removable prosthodontic appliances an invasive procedure?
No
What patients are at increased risk of infective endocarditis?
Acquired valvular heart disease with stenosis or regurgitation
Hypertrophic cardiomyopathy
Previous IE
Structural congenital heart disease including surgically corrected or palliated structural conditions, but EXCLUDING isolated atrial septal defect, fully repaired ventricular septal defect or fully repaired patent ductus arteries us and closure devices that are endothelialised
Valve replacement
What subgroups require special consideration regarding antibiotic prophylaxis?
Prosthetic valve
Previous IE
Congenital heart disease
What is congenital heart disease?
General term for a range of birth defects that affect the way the heart works.
What is cyanotic congenital heart disease?
Involves heart defects that reduce the amount of oxygen delivered to the rest of your body
What is aortic stenosis?
Heart valvular disease - the aortic valve between lower left ventricle and the aorta is narrowed and doesn’t open fully
What is valve regurgitation?
Type of valvular disease where the valve between the atrium and ventricle does not close properly, allowing blood to flow backward across the valve
What is hypertrophic cardiomyopathy?
Disease in which the heart muscle cells enlarge and the heart muscle becomes thickened. The heart chambers reduce in size, cannot hold the same volume of blood, cannot relax properly, may stiffen, so flow of blood may be obstructed.
What is an atrial septal defect?
Birth defect of the heart in which there is a hole in the septum that divides the upper atria of the heart
What is a patent ductus arteriosus?
A persistent opening between the two major blood vessels leading from the heart (aorta and pulmonary artery).
Who may require anaphylactic prophylaxis?
Special consideration sub-group - contact their cardiology consultant
If AP is indicated - when should AP be taken?
60mins before procedure
What drug is usually used for AP (no allergy to penicillin) and in what dose?
Amoxicillin, 3g oral powder sachet 60mins prior to treatment (adult)
Child : amoxicillin oral suspension, 250mg/5ml or 3g oral powder sachet
6ths-17yrs : 50mg/kg max dose. 3g
What is an appropriate AP oral regimen for patients who are allergic to penicillin? and what dose?
Clindamycin capsules (300mg)
Give 2 capsules (600mg) 60 mins before procedure - adults
children - 20mg/kg up to 600mg
For a patient who has received a course of antibiotics for infection within the last 6 weeks what could we prescribe for AP?
Select a drug from a different antibiotic class
In a patient with history of MI what should you ask and how might it impact treatment?
When MI was and if within 6 months then any routine treatment and use of adrenaline-containing LA should be avoided.
In a patient with angina, what should you ask?
If they have a prescribed GTN Spray, how stable is angina, how often GTN is used, patient should have GTN with them
What are the characteristics of Type IV latex allergy and what is their endodontic relevance?
Allergic contact dermatitis
Use latex free rubber dam
Safe to use GP cones
What are the characteristics of Type I latex allergy and what are their endodontic relevance?
Anaphylactic reaction
requires latex-free room
latex-free rubber dam, no latex/rubber containing materials
observe closely and be prepared to manage anaphylactic reaction
How can tuberculosis mimic periapical disease?
involvement of lymph nodes and lymphoma may mimic node enlargement due to dental problem
How can iron deficiency anaemia, pernicious anaemia or leukaemia mimic periapical disease?
paraesthesia of the soft tissues
How can sickle cell anaemia mimic periapical disease?
bone pain which mimics odontogenic pain and loss of trabecular bone pattern which mimics a lesion
How can multiple myeloma mimic periapical disease?
unexplained mobility of teeth
How can radiation to the jaws mimic periapical disease?
increased tooth sensitivity, osteoradionecrosis and incomplete root development may mimic “old” resorption
How can trigeminal neuralgia mimic periapical disease?
referred pain from cardiac angina
How can acute sinusitis mimic periapical disease?
toothache (teeth sensitive to cold and percussion)
What is apical periodontitis?
an inflammatory disease of microbial aetiology caused by infection of the root canal system which results in bone resorption around the roots
What is an apical lesion?
apical lesions represent a protective activity of the host response to prevent pathogenic bacteria in root canals from spreading to adjacent bone and throughout the body
What is the “price tag” of the protection supplied by an apical lesion?
destruction of the surrounding apical bone
Does dentinal exposure represent a significant route of infect?
No, except when dentine thickness is reduced or permeability increased
Do host defences function in a necrotic pulp?
No
How does a vital pulp offer protection?
Outward movement of dentinal fluid
tubular contents (blocking mechanism)
tertiary dentine
host defence molecules
What three things can cause pulpal inflammation?
Microorganisms
mechanical trauma
chemical irritation
What two components cause apical periodontitis?
necrotic pulp plus microbial infection
The pulp becomes inflamed when bacteria are within what distance of it?
0.5mm
What is the diameter of the dentinal tubules at their largest near the pulp?
2.5micro m
What is the microbial diameter in endodontic infection?
0.2-0.7 micro m
Name three chronic inflammatory cells
Macrophages, lymphocytes, plasma cells
Name 5 mechanical injuries that can create routes for root canal infection
traumatic incident
iatrogenic damage during procedure
excessive ortho procedures
sub-gingival scaling
attrition/abrasion
What is an impact injury trauma to the crown and how can this cause root canal infection?
Crown remains intact, microcracks present allowing bacteria to reach pulp, blood flow damaged
How can a route for root canal infection be created during crown/bridge preparation?
accidental exposure
inadequate water spray
overdrying of exposed dentine
inadequate isolation from saliva
failure to seal and protect tubules
Once a pulp has been exposed what are the two main subsequent processes
1) remains inflamed for a long time
2) undergoes necrosis slowly or rapidly
Whether the pulp undergoes necrosis or just stays inflamed for a long time can depend on what factors?
bacterial virulence
inflammatory response
host resistance
amount of circulation
lymphatic drainage
Name four inflammatory mediators
histamine
bradykinin
arachidonic acid
neuropeptides
Name three types of immunocompetent cells
T and B lymphocytes
Macrophages
Dendritic cells
Explain the coronal region of the tooth in regards to its suitability for survival of microbes
higher oxygen tension
nutrients from oral cavity
higher bacterial counts
microorganisms more accessible to treatment
Explain the apical region of the tooth in regards to its suitability for survival of microbes
lower oxygen tension
nutrients from periradicular tissues eg. proteins and glycoproteins
lower bacterial counts
bacteria less accessible for treatment
What substances provide nutrients for endodontic microbes?
proteins and glycoproteins
degradation of pulpal tissue
exudate
Name two types of black pigmented bacteria present in primary cases of endodontic infection
prevotella, porphyromonas
Is enterococci found in a higher percentage of primary endo cases or root filled teeth?
Root filled teeth - 29-77%
Primary cases - 5%
What is a biofilm?
A sessile multi-cellular microbial community characterised by cells that are firmly attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substances (EPS)
What percentage of an endodontic biofilm is composed of matrix?
85%
What is an endodontic matrix composed of?
extracellular polymeric substances
What kind of mediated infection is endodontic disease?
A biofilm-mediated infection
What is an isthmus?
A small, ribbon-shaped communication between two root canals that contains pulp or pulpally derived tissue
When is root canal treatment indicated in teeth?
where the dental pulp is irreversibly damaged (irreversible pulpitis, pulpal necrosis) and periapical disease.
What are the symptoms of a reversible pulpitis?
Pain - short and sharp, not spontaneous
stimulus - cold, sweet sometimes hot
no significant radiographic changes
What are the causes of reversible pulpitis?
caries into dentine, fractures, restorative procedures, trauma
When does irreversible pulpitis occur?
if the inflammatory process of a reversible pulpitis continues
Explain the symptoms of a symptomatic irreversible pulpitis
sharp pain on thermal stimulus which lingers
pulp allodynia
spontaneous pain
pain relieved by cold
referred pain
accentuated by postural changes
Explain the symptoms of a symptomatic irreversible pulpitis
sharp pain on thermal stimulus which lingers
pulp allodynia
spontaneous pain
pain relieved by cold
referred pain
accentuated by postural changes
What is pulpal allodynia?
episodes of diffuse, dull and throbbing tooth pain that develops when returning to an indoor room temperature after being exposed for a long period to cold weather
Explain the symptoms of an asymptomatic irreversible pulpitis
no clinical symptoms
usually respond normally to sensitivity testing
may have had deep caries or trauma that would likely result in exposure following removal
Is a tooth with irreversible pulpitis TTP?
No, as inflammation has not yet reached the periapical tissues
What is pulpal necrosis?
Breakdown of pulpal tissue allowing bacteria to colonise the root canal system
What happens to venules and lymphatics of the pulp during pulpal necrosis?
They collapse under the increased tissue pressure
What is liquefaction necrosis?
type of necrosis which results in a transformation of the tissue into a liquid viscous mass
What type of pulpitis causes liquefaction necrosis?
irreversible pulpitis
What is ischaemic necrosis?
trauma on the tooth causes damage to the blood vessels entering the pulp so that the whole intrapulpal circulation is permanently stopped
What can cause ischaemic necrosis of the tooth?
Trauma
Does pulpal necrosis show symptoms?
usually asymptomatic unless inflammation has reached the periapical tissues.
How does a necrotic pulp respond to sensibility testing?
No response
During periapical pathology, what do epithelial cells in the PDL do?
Proliferate to form a granuloma or cyst
What are the periapical tissues like in a reversible or irreversible pulpitis?
Normal
What are some possible causes of transient periapical periodontitis?
chemicals used in RCT
occlusal trauma
RCT over-instrumentation
What are the symptoms of symptomatic periapical periodontitis?
discomfort on chewing/biting
sensitivity to percussion
sensibility testing will depend if pulp is irreversibly inflamed or necrotic
radiographically periapical changes present
What radiographic changes are present in periapical periodontitis?
Loss of lamina dura and widening of PDL
Periapical radiolucency
What is the cause of an acute periapical abscess?
bacteria have progressed into periapical tissues and the patient’s immune system cannot defend against the infection
What are the symptoms of an acute periapical abscess?
rapid onset
pus formation
systemic involvement
pain - very TTP
mobility of tooth
swelling - depending on location
What does the term “phoenix abscess” refer to?
relates to the sudden exacerbation of a previously symptomless periradicular lesion
What would the radiographic appearance of a tooth with an acute periapical abscess be like?
PDL may be normal, slightly widened or have a distinct radiolucency if an acute flare up of a chronic lesion
What are the treatment options for an acute periapical abscess?
emergency - drainage via incision or through root canal
Then RCT or extraction
When does an asymptomatic periapical periodontitis occur?
when bacterial products from a necrotic or pulpless tooth slowly ingress the periapical tissues
What is a chronic periapical abscess?
an inflammatory reaction to pulpal infection and necrosis characterised by a gradual onset, little or no discomfort and intermittent discharge through an associated sinus
What are the symptoms of a chronic periapical abscess?
Usually asymptomatic
non-responsive to percussion, palpation and sensibility tests
sinus tract usually on buccal/labial sulcus
What will a chronic periapical abscess appear like radiographically?
radiolucent area on bone
What is the difference between reversible pulpitis and dentine hypersensitivity?
Reversible pulpitis has a specific causative factor present eg caries, defective restoration etc whereas dentine hypersensitivity does not.
What symptoms are present in dentine hypersensitivity?
Sharp, transient pain
cannot be attributed to other dental cause eg. caries, defective filling
What types of stimuli can cause pain in dentine hypersensitivity?
thermal, chemical, osmotic, tactile or physical
What causes the A delta fibres to be activated in dentine hypersensitivity?
fluid movement in the dentinal tubules
What causes dental hypersensitivity?
Tooth surface loss
gingival recession
What is focal sclerosing osteomyelitis (condensing osteitis)?
periapical lesion that involves reactive osteogenesis evoked by chronic inflammation of the dental pulp
Radiographically, what does a tooth with sclerosing osteomyelitis look like?
increased radiodensity and opacity around one or more roots
What are the symptoms of a cracked tooth?
Sharp, shooting pain on biting hard objects
may be worse on release of pressure
sensitivity to thermal changes
Name the 5 types of tooth cracks in order of least to most damaging
Craze lines
Fractured cusp
Cracked tooth
Split tooth
Vertical fracture
Where are craze lines detected and how are they visualised?
affect only enamel on the cross-marginal ridges and buccal, lingual surfaces
diagnosed by transillumination
What is a fractured cusp?
A complete or incomplete fracture initiated from the crown
How is a fractured cusp restored?
By removing the cusp and restoring, only RCT if crack affects pulp
What is a cracked tooth?
an incomplete fracture initiated in the crown and extending subgingivally, usually in the M-D aspect
What is a split tooth?
Complete fracture initiated from the crown and extending subgingivally, usually in the M-D aspect. More centred occlusally and extends to apex
What is a vertical root fracture?
complete or incomplete fracture initiated from the root at any level, usually B-L aspect.
What are the symptoms of a periodontal abscess?
rapid onset
spontaneous pain
TTP
swelling
pus formation
deep perio pocket
sensibility testing normal
Name two clinical periapical tests
percussion
palpation
Name two clinical periodontal tests
BPE
Mobility
What are the two main causes of “intense pain”?
Irreversible pulpitis
Acute periapical abscess
What is the maximum dose of paracetamol?
4g in 24hrs for a 70kg person
(8 x 500mg tablets)
How often must a medical history form be updated?
every 2 years
If there is a swelling of the tonsils or pharynx, what space has been affected and what is the origin or linked IO swelling?
Parapharyngeal space
severe swelling of both upper and lower molars
If there has been a swelling of the posterior cheek, what space is this and what might the origin be?
Buccal space
buccal roots of upper premolars and molars and lower premolars and first molars.
For the buccal space to be involved in a swelling, where must the roots of the teeth be?
the apices of the upper teeth must lie below the attachment of the buccinator to the maxilla and for the lower teeth, above the buccinator attachment to the mandible
If there has been loss of definition to the nasolabial fold, what space has been affected by swelling and what may be the origin or linked IO swelling?
Canine space
upper canine or very long central incisor, swelling on labial aspect
If there has been swelling in the submandibular area, what space has been affected and where might the origin be?
Sublingual space
usually lower 7s and 8s, infection exits on lingual side and apices must be above the mylohyoid attachment
swelling is bilateral
If there is swelling of the submental area what space has been affected and what might be the origin?
Submental space
lower incisors
If there is a swelling of the chin what space has been affected and what might be the origin?
labial aspect of lower incisors (area)
lower incisors (origin)
Which teeth can spread infection into the anterior part of the palate space?
Upper 2s - over 50% of 2s have apex in palatal or distal position
or palatal root of 4s
What can pass infection into the posterior palate space?
palatal root of molars
What does palpation determine?
If inflammation has extended periapically
What is the most accurate determinant of pulp vitality?
Vascular supply NOT innervation
What kind of image does a cone beam CT produce?
3D scan maxillo-facial skeleton at low radiation , captures cylindrical or spherical volume of data
The radiation exposure of a CBCT is equivalent to how many PA radiographs?
2-3
Following RCT, when is a follow up visit necessary?
at least 1 year after treatment and then further follow up for up to 4 years
Name 4 prognostic factors in root canal treatment
1) pre-operative absence of periapical radiolucency
2) root canal filling with no voids
3) RCF extending within 2mm of apex
4) satisfactory coronal seal
What percentage of primary treatments without periradicular periodontitis are successful?
92%
What percentage of primary treatments with periradicular periodontitis are successful?
74%
What percentage of the surface area of the mouth do teeth make up?
20%
Is rubber dam legally necessary for endodontics?
Yes
What thickness are each of the following rubber dam sheets? - thin, medium, heavy, extra heavy, super heavy
0.15mm, 0.2, 0.25, 0.3, 0.35
Name 5 clamp designs
Winged
wingless
passive
active
anterior
What are the benefits of a winged clamp and when do you place the sheet on it?
Additional soft tissue retraction
clamp placed with sheet attached
When placing a wingless rubber dam clamp, when is the sheet placed?
After the clamp has been applied
Describe the way a passive clamp engages the tooth
4 points of contact have a flat approach to the crown, not aggressive
suits intact crowns of molars and premolars
When is an active clamp used and what is a disadvantage of it?
if a tooth is badly broken down, partially erupted or has no undercut.
Aggressive - may traumatise tissues
What is a disadvantage of an anterior clamp?
Very aggressive
uses teeth with minimal coronal tooth structure and retracts gingival tissues
What is an oro-shield?
tissue napkin for patient’s face between skin and rubber dam
What is a wedget and when are they used?
elastic cord used when placing rubber dam as emergency without clamp OR if placing a clamp on one side of the arch and wish to stabilise the sheet on the other side
What material may be paced in spaces around teeth to prevent saliva percolating up past the rubber dam?
Caulking material or rubber dam liquid
How is rubber dam liquid set to ensure a fluid tight seal?
Light curing
Before placing rubber dam, what mouthwash may you get your patient to use and for how long?
1% hydrogen peroxide or 0.2% iodoporidone for 30 seconds
What affects whether you use an active or passive clamp?
Tooth structure
broken down - active
What must you always do before placing a clamp?
Floss it so it is easily retrievable from the mouth
What method can be used to place rubber dam on the anteriors without using an aggressive clamp?
Punch a series of 8 holes and place a clamp on the premolartooth, stretch rubber dam from premolar to premolar
Explain the split dam technique
clamps placed on teeth mesial and distal to the tooth requiring treatment.
3 holes made and joined together, dam stretched over the 3 teeth, requires extra protection from leakage by using CW rolls and saliva ejectors.
When would a split dam technique be necessary
broken down teeth or bridgework
Where is the root apex of a maxillary lateral incisor placed?
Palatally
What is the longest tooth in the mouth?
Maxillary canine
How many roots and canals does a maxillary 1st premolar typically have?
2 roots and 2 canals
If there is an extra root canals present in an upper first premolar, where is it likely to be found?
Buccal root
How many roots and canals does an upper second premolar typically have?
1 root and 1 canal
How many roots does an upper 1st molar have?
3 roots
Of the 3 roots in an upper 1st molar, which is the longest?
Palatal root
How many root canals are there in an upper first molar and where are they placed?
4
MB1, MB2, D, P
How many roots are there on a maxillary second molar?
3 roots
How many root canals are there in a maxillary second molar and where are they placed?
3 canals (4 less frequent)
MB, D, P
How many root canals are there in a mandibular central incisor usually and how often are there more than this found?
1 root canal
42% 2 root canals
How many root canals are there in a mandibular lateral incisor usually and how often are there more than this found?
1 root canal
42% 2 root canals
How many roots and root canals does a mandibular canine typically have?
1 root and 1 canal
How many roots and root canals does a mandibular 1st premolar typically have?
1 root and 1 canal
How many roots and root canals does a mandibular second premolar have?
1 root and 1 canal
Which mandibular premolar most commonly branches into two canals?
first premolar
How many roots and root canals does a mandibular first molar typically have?
2 roots, 3 canals
Where are the root canals placed in a mandibular first molar?
MB, ML, D
What percentage of mandibular first molars have 4 canals instead of 3?
33%
How many roots and root canals does a mandibular second molar typically have?
2 roots, 3 canals
Where are the root canals placed in a mandibular second molar?
MB, ML, D
Which bur is used to cut the initial outline form of the access cavity?
Small round diamond
How deep should the initial outline form of the access cavity be cut?
1mm deep
Which bur is then used to deepen the initial outline form towards the pulp chamber, eventually penetrating it?
Long fissure diamond
At what angle do you cut into the access cavity to the midpoint before changing direction to head for the pulp?
45 degrees to the palatal surface
What kind of bur would be used to gain access through a metal crown?
Tungsten carbide bur
What combination of burs would be used to gain access through a metal ceramic crown?
Diamond bur to cut porcelain and then tungsten carbide once metal exposed
What kind of bur would be used to gain access through a ceramic crown (zirconium or lithium disilicate)?
Specialised burs as zirconium is extremely hard
Komet ZR Diamond or SS White Great White Z
What is a non-end cutting high speed bur used for?
Used after completion of access to flare, flatten and finish axial walls
What is a non-cutting high speed bur made of?
Diamond or tungsten carbide
What shape is the access cavity for a maxillary central and lateral incisor?
Triangular
What shape is the access cavity for a maxillary or mandibular canine?
Ovoid
What is the fissure bur used to remove in the cutting of the access cavity?
Roof of the pulp chamber and the palatal shelf
What must be removed to ensure straight line access to the root canal?
Palatal shelf
What shape is the access cavity for a premolar?
Ovoid
Where is the pulp chamber placed in a mandibular first premolar?
Under the buccal cusp
What does the cleaning and disinfection of the root canal system aim to remove?
Organic pulp debris, microorganisms and toxins
What shape are we aiming for in when shaping in endodontic treatment?
A continuously tapering funnel shape
What can be used to measure the length of files?
Endoblock
Where should dirty files be placed during RCT?
Endopot
What two materials are root canal instruments made of?
Stainless steel
Nickel titanium
What type of files are made of stainless steel and what are they used for?
Hand files - for initial negotiation
What type of files are made of nickel titanium and what are they used for?
rotary files - used to shape the canal
If curved canals are instrumented as if they are straight, what happens?
Ledging occurs
What are four drawbacks of conventional hand stainless steel preparation?
mishaps - ledges, blockage, zipping
debris extrusion
time consuming
less predictable shapes in curved canals
Describe the movements of files in the balanced force technique
1) passive clockwise rotation of 60 degrees - engages dentine
2) anti-clockwise rotation with apical pressure of 120 degrees - cutting stroke
3) remove file with another 60 degree clockwise rotation then clean - clear debris
The balanced force technique requires canals of what apical diameter?
diameter more than size 50 (F5)
When is a balanced force technique used?
when a canal is too wide to be shaped by a ProTaper sequence
Are files pre-curved in the balanced force technique?
No
Can instrumentation alone eradicate endodontic infection or lead to healing of a lesion?
no
Can NiTi files be used in the slow speed handpiece?
Never
List 4 advantages of rotary NiTi instrumentation
1) less canal transportation
2) less debris extrusion
3) faster than hand preparation
4) more predictable results
What does the word torque describe?
Forces that move in a rotational manner
How does the taper of a file affect the torque required?
smaller, less tapered files require less torque
more tapered files require more torque
When will an instrument fail by torsion?
When the ultimate shear strength is exceeded
What is an example of an issue which can cause the ultimate shear strength to be exceeded causing instrument fracture?
when the tip or other part of instrument binds to the canal wall, whereas the handpiece continues to rotate
What causes flexural fracture/cyclical fracture?
continuous rotation in curved canals
instrument subjected to tension and compression cycles at point of maximum flexure
What does the risk of cyclical fracture increase with?
Time
Is flexural or cyclical fracture influenced by the operator?
No
Is removal of a broken file in the apical third practical?
No, not without risk of damage
When can you attempt the removal of a broken file?
Only when it is within the middle/coronal third and straight line access is possible
How does the timing of instrument fracture affect the treatment outcome?
The earlier in the instrumentation procedure it occurred, the greater the likelihood of inadequate cleaning
What should initially be attempted following instrument fracture?
attempt to bypass the fragment by careful use of hand instruments
What are the three file lengths available in ProTaper gold sequence?
21mm, 25mm and 31mm
Name the three ProTaper Gold shaping files
SX, S1, S2
Name the five ProTaper Gold finishing files
F1, F2, F3, F4, F5
What is a benefit of ProTaper Gold over ProTaper Universal?
Much more flexible
What is the variable taper concept?
Taper of the file changes along its length and is different for each file in the sequence
What are two main advantages of a variable taper?
each file preferentially cuts a certain part of the canal
much less likely to have the file stick in the canal and fracture
How long are the normal ProTaper file handles?
11mm
What is the tooth length or “estimated working length”?
Length from incisal edge to radiographic apex
In which teeth must you remove pulp horns in access cavity preparation?
Central incisors
What do we use to irrigate canals?
Sodium hypochlorite
What kind of probe do we use to locate canals?
DG16 (endodontic probe)
What ProTaper Gold file do we use to create the coronal flare?
SX
What is Glyde?
A paste lubricant
What size of SS flexofile can be used to negotiate the canal initially?
Size 10 (or drop to 08 or 06 if too tight)
When is the only time paste lubricants can be used?
Only with stainless steel files during glide path
What can glyde NEVER be used with?
Rotary files
The working length should be as close as possible to what?
CDJ - usually the apical constriction
How do electronic apex locators work?
By using the body to complete an electrical circuit - measures the electrical impedance between the lip and the file in the mouth
When using Electronic apex locators, what is the known impedance value?
The impedance between the lip and the PDL
Where is an acceptable working length radiographically?
within 2mm of the radiographic apex
What radiographic technique is used to capture the working length radiograph?
Paralleling technique
What is apical patency?
the ability to pass a small flexofile passively through the apical constriction without widening it
Why is the glide path so important?
creates and confirms a smooth reproducible path of adequate diameter before introducing rotary files
What is the endodontic glide path?
a pre-existing part of the original anatomy - natural space once occupied by the dental pulp
How do you prepare the glide path?
locate the canal orifice
follow canal to apical constriction with size 10 flexofile
record WL and confirm patency
use short push pull strokes until size 10 is super loose in canal
How deep is the coronal flare?
2-3mm
What do we use to enhance the glide path once it has been negotiated with the size 10 flexofile?
Proglider
What is the ProGlider and what is it made from?
Rotary file
Made of M wire NiTi
At what settings and in what motion is the proglider used?
300rpm
2 Ncm (torque)
in short in and out motions
What must we always to do canals when using rotary files?
ensure they are wet using sodium hypochlorite irrigant as lubricant
Can you stop or start a rotary instrument in the canal?
No
Name 4 factors that may prevent passive movement of a file
1) insufficient glide path
2) build-up of debris in canal
3) build-up of debris on flutes of file
4) complicated root anatomy
What settings are used for shaping files?
300rpm
4Ncm
What is apical preparation carried out to determine?
the diameter of the canal at the apical constriction to finish canal preparation to this size - apical gauging
List the diameters of the F1, F2, F3, F4 and F5 files
0.2mm
0.25mm
0.3mm
0.4mm
0.5mm
Explain the process of finishing the root canal
use F1 to WL
gauge with size 20 flexofile - if snug at length and debris on apical portion then prep is complete.
if not - continue to F2 to WL and repeat apical gauging up to F5 if needed
If the diameter at the AC is more than size 50, how would you complete apical preparation?
use flexofiles using the balanced force technique
What is used to irrigate during final irrigation?
3ml sodium hypochlorite
3ml citric acid
3ml sodium hypochlorite
Following final irrigation what is done?
Canals dried with paper points and dressed
What are the canals dressed with following final irrigation and drying?
Non-setting calcium hydroxide, cotton wool/sponge, coltosol or glass ionomer
What is coltosol?
temporary, eugenol-free filling material
Once a temporary dressing has been applied, what measurements must be recorded in the patients notes for the next appointment?
Working length
reference point for each canal
Apical size (F1-F5)
What is non-setting calcium hydroxide?
an inter-appointment medicament
Name two types of non-setting calcium hydroxide
Ultracal
Hypocal
What corticosteroid is contained in odontopaste?
Triamcinolone
What antibiotic is contained in odontopaste?
Clindamycin hydrochloride
What is the benefit of the corticosteroid, triamcinolone, in odontopaste?
anti-inflammatory causing rapid pain relief
inhibits clastic cells - may manage inflammatory bone resorption
What is the benefit of the antibiotic clindamycin in odontopaste?
Antimicrobial action (limited)
What is odontopaste?
zinc-oxide based endodontic dressing used to reduce pain, as well as to maintain a bacteria-free environment within the root canal
When would you use odontopaste?
In the management of symptomatic irreversible pulpitis or as a pulpotomy agent
What does odontopaste have an anti-inflammatory action on?
remaining pulp tissue and periapical tissues by diffusion through apical foramen
Comment on the antibacterial action of odontopaste
It is short-lived and does not penetrate into the dentinal tubules
How long should odontopaste be used to resolve inflammation?
4-6 weeks
When can odontopaste be used as an intracanal medicament?
when mixed 50/50 with calcium hydroxide
Why is odontopaste contraindicated in pregnant women?
has been shown to have teratogenic effects
Odontopaste should not be used on patients with which allergies?
Clindamycin or lincomycin
Describe the stages involved in emergency pulpotomy
1) LA
2) Rubber dam
3) open pulp chamber completely
4) wash with sodium hypochlorite
5) amputate coronal stump with high speed
6) wash and dry with CW
7) seal odontopaste/ledermix into chamber on a small piece of CW
How should you test that a tooth is adequately anaesthetised for RCT?
Cold - if they do not feel cold then it is anaesthetised
How can an inflamed pulp affect local anaesthetic?
Inflamed pulp means high H+ concn and low pH, which can cause either a slow onset or failure of LA
Anaesthetic exists in what two forms
it is a salt
uncharged state or charged state
What channels does LA act to block?
reversibly block sodium channels - hold them closed
To pass through the axon membrane and act upon the sodium channels, what state must LA molecules be in?
only UNCHARGED portion of LA can pass through the axon membrane
Once the uncharged LA portion has passed to the aqueous inside of the nerve, what happens to allow it to have effect?
it will re-equilibriate once inside the nerve and the CHARGED portion will bind to the sodium channel and take effect
In what state must LA be in to act on the sodium channels inside the nerve and successfully close the channels?
CHARGED
Why does the high concentration of H+ ions in an inflamed or infected pulp affect LA?
Low pH means lots of H+ ions. The abundance of H+ ions favours more charged LA, so when LA is injected there is less uncharged LA to pass across the axon membrane into the nerve, therefore less LA to re-equilibriate inside the nerve and less charged ions inside to act upon sodium channels.
What affect can inflammation have on nerves, tissue pressure and blood flow?
hyper-algesia - sensitises nerves which can make them more resistant to LA
increases tissue pressure
increases blood flow
What is the gold standard block anaesthesia?
2% lidocaine and 1:80,000 adrenaline
What bespoke anaesthesia can be used as a plain drug without vasoconstrictor or preservative?
3% mepivacaine
What is another vasoconstrictor used in LA other than adrenaline?
Felypressin
Where does felypressin act?
Venous side of the vascular bed
Why is articaine said to have a low toxicity?
low toxicity due to rapid metabolism in the plasma and liver, high protein binding
What is an intraligamentary injection and how does it work?
injecting under pressure between the tooth and bone. Anaesthetic diffuses out of PDL through porous bone of socket into cancellous bone and diffuses to apex.
What is calciject?
computer controlled anaesthesia - controls dose, pressure etc
What is intraosseous anaesthesia?
infiltrate the area if injection intraosseously by perforating bone and passing the needle through the hole into cancellous or trabecular bone to overcome the thick cortical plate
What are three factors determining the type of microbial species present in different areas?
availability of nutrients
oxygen level
local pH
What are two commonly used root canal irrigants that remove the smear layer?
Citric acid
EDTA - 17% ethylenediamine tetraacetic acid
What are two commonly used root canal irrigants that are antimicrobial?
sodium hypochlorite
2% Chlorhexidine
What is a large benefit of irrigating using sodium hypochlorite?
It is antimicrobial AND is capable of dissolving necrotic (organic) tissue
What is a good rule of thumb for necessary volume of irrigant used?
20ml per canal
What are three disadvantages of using sodium hypochlorite irrigant?
unpleasant taste
high toxicity
does not remove smear layer alone
What affect would sodium hypochlorite infiltrating tissues beyond the root apex have?
extreme pain, burning sensation
swelling, 2nd infection
ecchymosis, haematoma
In the event of a sodium hypochlorite incident, what would you tell the patient and how is it managed?
focus on minimising swelling, controlling pain and preventing secondary infection
analgesics
external compression with cold packs replaced with warm compresses for several days
antibiotics and/or OS referral in some cases
What is the endodontic smear layer?
layer that covers the instrumented walls containing inorganic and organic substances, microorganisms and necrotic material
Why must the smear layer be removed?
It protects the microbes in the dentinal tubules from effects of disinfectants and prevents complete adaptation of obturation materials to canal surfaces
Which two acids are examples of chelating agents that can remove the smear layer?
17% EDTA - ethylenediamine tetraacetic acid
40% Citric acid
How does EDTA work to remove the smear layer?
reacts with calcium ions in dentine. to form soluble calcium chelates
works with NaOCl which dissolves organic components
What kind of syringe is used for irrigation?
3ml Luer Lock syringe
What does a calcium hydroxide medicament do?
Kills bacteria and inactivates endotoxin
reduces inflammation
helps eliminate apical exudate
controls inflammatory root resorption
prevents contamination between appointments
Name three ways CaOH acts in an antibacterial way
1) damages bacterial cytoplasmic membrane by chemical injury
2) protein denaturation
3) damage to DNA
What is a weeping canal?
canal from which constant clear or reddish exudation is appeared
How is a weeping canal managed?
Use CaOH to dress the canal - calcifying potential, high pH, may cauterise residual chronically inflamed pulp
How do you place a temporary filling?
place a small piece of CW over canal orifice
place small piece of coltosol over it
temporise with GI
remove rubber dam and check occlusion
How does obturation eliminate leakage?
reduces coronal leakage and bacterial contamination
seals apex from periapical tissue fluids
entombs remaining irritants in canal
What type of seal do we need during obturation?
Fluid tight or bacteria tight seal
Why is it preferred for a vital pulp to be fully prepped and obturated in one visit?
When there is a vital pulp as bacterial contamination is minimal and therefore this prevents contamination via leakage between visits
When can canal prep and obturation be completed in one visit?
no significant symptoms
no significant clinical signs - must NOT be TTP
canal must be clean and dry - no blood, exudate or pus
Is a necrotic pulp or a periapical radiolucency on a radiograph a contraindication to single visit treatment?
No
When must a patient be treated over multiple appointments?
presence of acute signs/symptoms/swelling
persistent exudate in canal
anatomical difficulties
technical difficulties
patient or dentist tired/lost patience
What is an advantage of a multiple appointment treatment?
Allows medication with an antibacterial dressing
How far from the radiographic apex does the apical constriction lie?
0.5-1mm
When placing GP cones and sealer what do we aim for volume wise?
Maximum GP and minimum sealer
Name 4 obturation techniques
1) cold lateral compaction
2) warm vertical compaction
3) continuous wave condensation
4) carrier based systems
What is the composition of gutta percha?
19-22% gutta percha
59-75% zinc oxide
10% radiopacifiers
5% plasticisers
What size of finger spreader is used in cold lateral compaction with gutta percha cones?
Size B finger spreader
Explain the steps involved in cold lateral compaction obturation
1) LA
2) Rubber dam
3) swab tooth with alcohol
4) remove dressing and CW
5) irrigate with citric acid to remove CaOH dressing then with sodium hypochlorite
6) take a cone-fit radiograph
7) dry canal wit paper points
8) mix sealer and have finger spreader ready
9) coat master apical cone in sealer and insert to correct WL
10) insert spreader and leave in place for 10-15secs with light lateral pressure
11) remove spreader with slight rotation and place accessory cone coated in sealer quickly into channel
12) repeat until no further accessory cones fit
13) cut off excess GP cones with headed instrument
14) compact coronal GP vertically using endodontic plugger
What is used to seal the pulpal floor to prevent coronal leakage?
resin modified GI
Smart dentine replacement (SDR)
How long is a the working blade and where does it start and stop?
16mm
begins at tip (D0) and extends along shaft terminating at D16
What is the diameter at D16?
D16 is 0.32mm greater than D0
D16 = D0 + (16 x 0.02)
What is the tip angle?
75 degrees +/- 15 degrees
What is the taper of conventional stainless steel instruments?
0.02 or 2%
meaning for every 1mm towards the shank, the diameter of the file increases by 0.02mm
In what increments do the diameter of stainless steel files increase sequentially?
by 0.05mm from size 10-60 (eg. 45, 50, 55, 60)
then by 0.1mm from 60-140 (eg. 120, 130,140)
The stainless steel hand files are iron alloys made with what amount of chromium?
minimum of 10.5% chromium
What shape of blocks are small stainless steel hand files manufactured from?
Square blocks - more resistant to torque fractures
What shape of blocks are large stainless steel hand files manufactured from?
Triangular blocks - improves cutting efficiency
What are barbed broaches used for?
Stainless steel file used for removing pulpal tissue in emergency pulp extripation
What is the non-aggressive tip of a flexofile called?
Batt tip
What motion can Hedstroem files be used in and why?
Up and down motion, they are very stiff
What is the metallurgy of NiTi?
56% Nickel
44% titanium
Explain the composition changes in NiTi when stress is applied
stress applied to austenite, causes martensite to form while at same time changing shape. Once stress is removed, the nitinol spontaneously returns to original shape
What is the unstressed form of NiTi?
Austenite
What is the stressed form of NiTi?
Martensite
Why can the inherent memory of NiTi sometimes be an issue in curved canals?
Due to the memory they will try to straighten which can lead to over-instrumentation, canal straightening or unfavourable stress leading to cyclical fatigue failure
What is EDTA?
Ethyldiamenetetraaectic acid
Chelating agent
What is carbamide peroxide and what is it found in?
Found in paste lubricants
it is an oxidising agent which emulsifies pulp remnants
What type of NiTi wire is made from a thermomechanical processing procedure?
M wire
What are the three crystalline phases of M wire?
1) deformed and microwrinned martensite
2) Premartensitic R-phase
3) Austenite
What are two large advantages of M wire?
Greater flexibility
Increased safety due to protection/ resistance against fracture
By how much is the resistance to cyclic fatigue increased by in M wire?
400%
What is the Proglider made from?
M-wire
What motion and settings is the Proglider used with?
In and out motion
300rpm, 2-5Ncm
What type of taper does the Proglider have?
2% progressive taper
Describe the concept of controlled memory files
new NiTi alloy subjected to. a thermomechanical process which allows it to demonstrate martensitic properties at room temperature, flexible with virtually no memory
What is a large advantage of controlled memory files?
They are martensitic and flexible so can adapt to curvatures or can be pre-curved but have virtually no memory
What are 4 advantages of NiTi over SS files
1) greater flexibility
2) greater cutting efficiency
3) better safety in use
4) more user friendly with simpler sequences
What is an advantage of large tapers?
greater taper allows for more effective disinfection of the RC system
What is the minimum taper a RC should be prepped to?
6%
What are four disadvantages of NiTi preparation?
1) instrument fracture
2) expense
3) access in posteriors difficult
4) unsuitable for complex canals
What is a common inter-appointment medicament?
Non-setting calcium hydroxide
What type of medicament do we NOT use for interappointment medicaments?
Phenolic compounds - highly toxic, possibly carcinogenic, not effective
What is the pH of calcium hydroxide?
pH 12.5-12.8, strong base
How does calcium hydroxide ionically dissociate on contact with aqueous fluid?
dissociates into Ca and OH ions
What are the effects of CaOH on tissues?
Induction of hard tissue deposition and anti-microbial effect
How does CaOH effect bacterial cells? 3 points
1) damages cytoplasmic membrane by chemical injury
2) protein denaturation
3) damage to DNA
How should CaOH be placed as an interappointment medicament?
canals dried with paper points
canal should be completely filled without extruding any excess
What is apexification?
the process of creating an environment within the root canal and peripheral tissues after pulp death that allows a calcified barrier to form across the open apex of an immature root
What barrier is formed from apexification?
osteo-cementum or other bone-like tissue
How can a horizontal root fracture be treated similarly to apexification?
the canal at the level of fracture is comparable to the apical foramen of an immature tooth so a barrier can be formed that allows the coronal portion to be obturated
Following a small iatrogenic perforation, what can be used to induce hard tissue barrier formation?
CaOH
What is the difference between internal and external resorption?
Internal is initiated within the pulp whereas external is initiated outside of the tooth
What surfaces and associated “blasts” protect the mineralised tissues?
pre-dentine and odontoblasts in the root canal
pre-cementum and cementoblasts on root surface
What happens if predentine and precementum become mineralised?
multinucleated cells colonise and internal resorption ensues
What is internal resorption a result of?
Chronic pulpitis - due to trauma, caries or iatrogenic procedures
If internal resorption is left untreated what will happen?
it will progress to perforate the root and pulp will become necrotic
Is internal resorption normally painful?
No, usually pain-free and only diagnosed during routine radiographs
What may be seen externally when there is internal resorption present in the pulp?
a pink spot - may be misdiagnosed as invasive cervical resorption but will have no surface defect
What is the treatment for internal resorption if it is not perforated?
extripate pulp, dress CaOH, dress with warm gutta percha
What is the treatment for internal resorption if it IS perforated?
defect must be sealed, surgically if accessible or intracanal using MTA (mineral trioxide aggregate)
What are the six types of external resorption?
1) surface resorption
2) inflammatory resorption
3) replacement resorption
4) pressure resorption
5) systemic resorption
6) idiopathic resorption
What are three treatment options for non-vital immature permanent incisor teeth?
1) Apexification
2) apical barrier
3) revascularisation
What is apexification?
method to induce a calcified barrier in a root with an open apex or the continued apical development of an incomplete root in teeth with necrotic pulp
What is done using the mineral trioxide aggregate method to provide an apical barrier?
MTA inserted to form a 4-5mm apical plug
radiograph taken to ensure correct level
remainder filled with warm GP at following appointment
What is the theory behind revascularisation?
in the absence of infection and presence of a suitable scaffold, ingrowth of tissue from the periapical region leads to revascularisation of the reticular pulp. As root development continues, dentinal walls thicken and apex closes
What is the procedure involved in revascularisation?
first visit - irrigation with NaClO, dressed with ciprofloxacin, methronidazole and minocycline for a week
2nd visit - confirm dry canal, size 40 flexofile used to irritate tissues causing bleeding, leave 15 mins to form clot and place MTA over clot, temporise with CW and coltosol
What are the two forms of gutta percha?
alpha and beta
What is the alpha form of gutta percha?
alpha phase when heated - tacky, soft, shrinks on cooling
What is the beta form of gutta percha?
solid mass that is compactable
What are three disadvantages of gutta percha?
1) lack of adhesion to dentine
2) when heated, shrinkage on cooling
3) cannot be heat sterilised - place cones in NaClO for 1 min
How can sealers cause some post-operative pain?
all exhibit toxicity when freshly mixed - reduces on setting
Name three examples of sealers
1) Zinc oxide eugenol
2) calcium hydroxide
3) epoxy resin
Give examples of two bioinert ceramics used in prosthodontics
1) Allumina
2) Zirconia
What is an example of a bioceramic used in endodontics as a root sealer or for pulp capping, pulpotomy, repair etc?
Calcium silicates
Do Bioceramic sealers shrink upon setting?
No, they expand slightly
Bioceramic sealers are hydrophilic, how does this affect RCT?
Means they utilise moisture within the canal to complete the setting reaction
Do calcium silicates shrink upon setting?
No, they are dimensionally stable and may even expand slightly
Are calcium silicates acidic at setting?
No, their pH at setting is 11-12 due to the hydration reaction forming CH and later dissociation into calcium and hydroxyl ions
What is a benefit of calcium silicates?
Antimicrobial properties
Name a first generation and second generation calcium silicate cement
1st - mineral trioxide aggregate
2nd -biodentine, bioaggregate
What is the setting time of mineral trioxide aggregate?
3hours
What is described as in ideal dentine replacement material?
Biodentine
How fast does biodentine set?
10-12 minutes
What does hydration of mineral trioxide aggregate produce?
a colloidal gel which solidifies into a hard structure with good marginal adaptation
What has a higher calcium ion level - biodentine or MTA?
Biodentine
What are the particle size of biodentine like in comparison to the particles in MTA?
smaller more uniform particle size in biodentine meaning they can end dentine tubules - higher push-out strength
In Vertucci’s canal configurations, which types have only one canal at the apex?
Type I, II and III
In Vertucci’s canal configurations, which types have two canals at the apex?
Type IV, V, VI and VII
In Vertucci’s canal configurations, which type has three canals at the apex?
Type VIII
What are the three distinct patterns in which accessory canals appear in mandibular first molars?
1) 13% - single furcation canal to interradicular region
2) 23% lateral canal from coronal third of major canal to furcation region
3) 10% both lateral and furcation canals
What is a rule of thumb for finding root canals?
You should not have to cross the oblique ridge, they are usually mesially placed
What is the distance from the pulpal floor to the furcation?
3mm
What is the pulp chamber height in a mandibular molar?
1.5mm
What is the pulp chamber height in a maxillary molar?
2mm
What is the height from the buccal cusp to the pulp chamber roof in both maxillary and mandibular molars?
6mm
What is the pulp chamber ceiling nearly always coincident with?
CEJ
How many root canals should you look for in all first molars?
4
What outline shape do we aim for with access cavities in maxillary molars?
Blunted triangle
Where should the blunted triangle cavity be positioned in a maxillary molar?
base towards buccal
apex towards palatal
orifice positioned at each angle
cavity entirely within mesial half
What outline shape do we aim for with access cavities in mandibular molars?
rhomboid shape to allow for exploration of 2nd distal canal
What type of memory do ProTaper gold instruments have?
Controlled memory
What cycles are used in ProTaper Gold instrument production to give them their properties?
multiple heating and cooling cycles - reaches optimal phase transformation from martensite to austenite
What instruments do you use in a brushing motion?
Shaping files - S1, S2
What irrigants are used in the final irrigation?
3ml NaClO
3ml citric acid
3ml NaClO
Once a temporary dressing has been removed, what is used to irrigate and to remove calcium hydroxide?
Citric acid
How do you obturate converging canals?
Seat one GP cone to full WL
Seat second as far as possible then remove it and measure its length
cut this length from the apical end and place in the canal
In oval shaped canals how much of the wall surface can be contacted by the instruments?
40%
Comment on the effectiveness of laminar flow of irrigants within root canals
will remove planktonic bacteria, only effective slightly beyond tip of needle.
Area of stagnation known as vapour lock effect
Comment on the effectivenss of turbulent flow of irrigants within root canals
acoustic streaming, cavitation
caused by agitation of irrigants, more likely to penetrate RCS and disrupt/remove biofilm
What is the frequency of cycles/second during ultrasonic disinfection of the RCS and what does this do?
25,000 cycles/second
acoustic streaming, cavitation and increase in temperature of irrigant shown to cause 80% less microbial growth
What is smart dentine replacement?
a flowable bulk filler that can be placed up to 4mm, self levels and minimises shrinkage stress
What is an endodontic emergency?
pain or swelling caused by various stages of inflammation or infection of the pulpal or periapical tissues
What is the maximum paracetamol dose in 24hrs?
4g
What is the maximum ibuprofen dose in 24hrs?
2.4g
What is the maximum diclofenac dose in 24hrs?
150mg
Which three analgesics can be prescribed for endodontic pain?
paracetamol
ibuprofen
diclofenac, co-codamol
What three antibiotics can be prescribed for dental infections in adults?
Amoxicillin
Phenoxymethylpenicillin
Metronidazole
What 5 day regimen would be given of paracetamol for endodontic pain? mild to mod pain
2x500mg tablets up to 4 times daily
What 5 day regimen would be given of ibuprofen for endodontic pain? mild to mod pain
2x200mg tablets up to 4 times daily preferably after food
For moderate to severe pain, how can analgesic dosages be changed?
1) paracetamol and ibuprofen together
2) increase ibuprofen to 3x200mg tablets up to 4 times daily
3) di-clofenac 1x50mg tablet 3x daily with paracetamol
What is a normal dosage of amoxicillin to be prescribed?
1x500mg capsule 3x daily
What is a normal dosage of phenoxymethylpenicillin to be prescribed?
1x250mg tablets 4x daily for 5 days
increased to 500mg for severe infection
What is a normal dosage of metronidazole to be prescribed?
1x400mg tablet 3x daily
How can dentine hypersensitivity be treated?
occlude dentinal tubules with agents - fluoride, varnishes, oxalates, adhesive systems, bioglass
disturb transmission of nerve impulses with agent - potassium nitrate
Do you prescribe antibiotics for advanced symptomatic pulpitis?
NO
What is vital pulp therapy for the treatment of IP?
complete removal of coronal pulp and application of biomaterial straight onto pulp tissue at level of orifices prior to the placement of a direct restoration
Once an acute apical abscess has been drained through the RC, what is done?
dress with CaOH and seal abscess
relieve occlusion
review in 24hours
When do we NOT prescribe antibiotics
irreversible pulpitis
symptomatic periapical periodontitis
draining sinus tracts (chronic abscess)
after endo surgery to prevent flare up
after incision for drainage of a local swelling (without cellulitis/fever/lymphadenopathy)
In what three instances would we prescribe antibiotics
1) when there is a diffuse swelling/cellulitis
2) drainage cannot be achieved
3) patient has systemic involvement
Is amoxicillin or phenoxymethylpenicillin the first port of call for an antibiotic?
Amoxicillin - effective at treating dental abscesses and better absorbed than phenoxymethylpenicillin
What kind of bacteria/microbes does phenoxymethylpenicillin act on?
facultative and strict anaerobes
gram positive facultative - streptococci, enterococci
anaerobes - porphyromonas, fusobacterium, actinomyces
Metronidazole is bactericidal against what kind of anaerobes?
Strict anaerobes
When is metronidazole often used?
When patients have a penicillin allergy
What affect can metronidazole have on patients taking warfarin?
anticoagulant effect of warfarin may be enhanced
In the incidence of LA failure due to inflammation, which LA can be used due to its low pKa value (acid strength)?
Mepivacaine (Scandonest 3%)
How can the effect of inflammation on blood flow reduce effectiveness of LA?
peripheral vasodilation induced by inflammatory mediators could reduce the concentration of LA by increasing the rate of systemic absorption
What effect can inflammation have on nociceptors?
inflammatory mediators can sensitise nociceptors or cause nerve sprouting, increasing the size of the receptive field.
Retreatment of teeth with apical periodontitis should ideally be done in how many appointments?
Not a single visit
What is cracked tooth syndrome?
incomplete fracture of the dentine in a vital posterior tooth that involves the dentine and occasionally extends into the pulp
What are three natural predisposing factors for tooth cracks?
1) lingual inclination of lingual cusps of mandibular molars
2) bruxism, clenching
3) extensive attrition, abrasion
What are two reasons older patients may have less moisture in teeth?
1) tubular sclerosis
2) secondary and reactionary dentine
What in the matrix of endodontically treated teeth is altered?
structure of collagen in matrix is altered - more immature cross links present which can cause decrease in tensile strength and increase in brittleness
What four areas should a preoperative evaluation assess?
1) endodontic
2) periodontal
3) restorative
4) aesthetic
What two areas make up the biologic width?
junctional epithelium and connective tissue
What are the supracrestal attached tissues?
previously biological width
band of soft tissue attachment from the alveolar bone to the coronal extent of the junctional epithelium
What is the average size of the biologic width/supracrestal attached tissues?
2-3mm
What is the function of a core and what do they replace?
a core material replaces missing coronal tooth structure prior to restoration with an indirect, extracoronal restoration and stabilises weakened parts of the tooth
When would you do a core build up without a post?
when there is more than 50% loss of the coronal tooth structure
What materials are contained in amalgam?
mixture of metals, consisting of liquid (elemental) mercury and a powdered alloy composed of silver, tin, and copper
Is amalgam slow or fast setting?
Slow setting - best left 24hrs before tooth prep
What is an advantage of amalgam cores and the fact amalgam is packable?
lessens likelihood of voids
What is a disadvantage of amalgam as a core material?
Not intrinsically adhesive - relies on mechanical retention
What can be utilised to achieve a bond between amalgam and the tooth cavity?
Amalgam bonding - self curing metal adhesives eg. resin cement, Panavia
What is composite resin composed of?
aromatic dimethacrylate (BisGMA), filler particles like quartz or silica
How quickly does composite resin set when used as a core?
immediately
Name two disadvantages of using composite resin as a core material
tooth coloured - hard to distinguish margin when placing crown
Moisture sensitive, polymerisation shrinkage
Is bulk placement recommended with conventional composites?
No
Why is bulk placement of conventional composites not recommended with cores?
get shrinkage - leakage
gap formation - caries, post op sensitivity
How can mechanical retention be gained for a core without a post?
pulp chamber in posterior teeth provdes natural undercut
Grooves or slots
pins
How can chemical retention be gained for cores wtihout posts?
Bonding of composite
Amalgam bonding of core
Does the fracture resistance of a Nayyar core depend on the material used?
No significant difference
What are 5 disadvantages of pins?
1) induce internal stresses
2) cause dentinal crazing
3) self shearing pins do not shear at full depth of pin hole
4) fracture resistance of core reduced
5) risk of perforation
If using pins, what three things should be done to lessen any risks?
1) use minimum number
2) coat in adhesive
3) avoid furcation area
When are posts required?
when there is a lack of coronal tooth structure to support a core
Do minimal palatal access restorations require a post?
no
Do posts reinforce pulpless teeth?
No they weaken them
Name four causes of post failure
1) perforation
2) root fracture
3) cement failure
4) coronal leakage
What appearance can pathology often present with radiographically following a root fracture?
J-shaped wrapped around root apex
When should the permanent restoration be placed following RCT?
as soon as possible following root canal treatment in the absence of symptoms
list four advantages of immediate post placement
1) familiarity with root canal morphology
2) less risk of post perforation
3) apical seal not disrupted
4) increased apical leakage after delayed post prep
What is used for the mechanical removal of GP before placing a post?
Gates gliddens burs in sequence
ProTaper D files
How must GP should be left apically prior to post placement?
4-5mm
How long should a post be?
As long as possible or at least 1:1 ratio with the crown of the tooth
What is the issue with short posts?
poor retention and transmit larger lateral forces so increased risk of root fracture
How big should the diameter of the post be?
no greater than 1/3 of the root
How is the ferrule effect provided?
by bracing of the remaining tooth structure by the indirect restoration NOT the remaining coronal tooth structure
What depth of ferrule is recommended labially and palatally?
1.5-2mm
What depth of ferrule is recommended mesially and distally?
1mm
Why are ferrules so important?
1) improves fracture resistance
2) reduce vertical fracture by 1/3
3) more important than core material and post
What can be done if there is insufficient coronal tooth structure for a ferrule?
1) orthodontically extrude tooth
2) crown lengthen
3) accept poorer prognosis
4) extract and replaced with bridge or implant
What are the two main types of post?
active or passive
What is an active post?
post which gains retention from root dentine by the use of threads
What is a passive post?
a post which relies on luting cement for retention
Name the eight types of posts
1) threaded
2) smooth sided
3) parallel sided
4) metal
5) serrated
6) cast
7) tapered
8) non-metal
place serrated, threaded and smooth posts in order of retention from most to least retentive
threaded > serrated > smooth
Which is more retentive, a parallel sided or tapered post?
parallel sided
What types of posts are considered active posts?
self threading
pre-tapped
What types of posts are considered passive posts?
cast posts
preformed, prefabricated posts
What type of post is a dentatus screw?
An active post - self threading
What is considered the least retentive post design with a high failure rate?
Cast post and cores - passive
smooth sided, tapered posts which conform to original taper of RC.
What do parallel sided serrated posts have to allow the escape of excess cement?
a vertical vent
What is an advantage of fibre posts regarding stresses?
The flex slightly under load and distribute stresses to the root dentine in a more favourable manner than metal posts
What does anisotropic mean and what is this word used to describe?
different physical properties when loaded from different directions.
fibre posts are anisotropic
What process allows for the formation of a superior resin tag formation?
removal of smear layer
etching, bonding using microbrush and application of adhesive resin cement
Adhesive resin composite can cause what issue and should not be used with what material?
make removal of posts difficult.
do not use as routine with metal posts - compromised retention could lead to surgery or extraction
What types of anterior teeth would be considered compromised?
1) non-vital, immature teeth
2) recurrent caries, pre-existing post
3) iatrogenic damage
4) internal resorption
5) developmental anomalies
6) loss of apical constriction
A contemporary technique of restoration forms an apical barrier using what before placing a quartz fibre post and composite core?
mineral trioxide aggregate (MTA)
What is the most accurate determinant of pulp vitality?
vascular supply, NOT pulpal innervation
What are we referring to when discussing pulp vitality?
blood supply
What are we referring to when discussing pulp sensibility?
nerve supply
Which nerve fibres result in acute sharp pain in teeth?
A delta fibres (90%) and A beta
Are A delta and A beta fibres myelinated?
yes
Do A delta and A beta fibres have a low or high threshold and how are they stimulated?
low threshold
stimulated by movement of dentinal fluid
What do A delta and A beta fibres innervate?
the dentine
What type of fibres innervate the main body of the pulp?
C fibres
What kind of threshold do C fibres have and are they myelinated?
high threshold
unmyelinated
What kind of pain does stimulation of C fibres of the pulp result in?
dull burning pain, poorly localised and can radiate
Can C fibres remain excitable after compromised blood flow to the pulp?
yes
Name four key uses of pulp testing
1) prior to operative procedures
2) diagnosis of pain
3) investigation of radiolucent areas
4) post-trauma assessment
Does a positive result to a sensibility test guarentee a healthy pulp?
No, not a quantitative test but helpful to identify diseased tooth.
What does a positive sensibility test indicate?
presence of some nerve fibres carrying sensory impulses
Name four examples of sensibility tests
1) thermal testing
2) electric pulp testing
3) test cavity preparation
4) local anaesthetic test
What does a normal response to a sensibility test indicate?
vital tooth or reversible pulpitis
What does an intense, prolonged response to a sensibility test indicate?
suggestive of irreversible pulpitis
What does no response to a sensibility test indicate?
necrotic pulp
false negative
What can cause a false negative sensibility test?
Calcified canal
immature apex
recent trauma
A response to cold usually indicates what?
a vital pulp, regardless of whether it is normal or compromised
An increased response to heat can be suggestive of what?
pulpal/periapical pathology that may require endodontic intervention
What does the application of a cold test cause?
contraction of dentinal fluid within the tubules, resulting in rapid outward flow causing hydrodynamic forces to act on A delta fibres leading to a sharp sensation
How can a cold test identify between reversible and irreversible pulpitis?
reversible -pain subsides on removal of stimulus
irreversible - pain lingers after removal of stimulus
What temperature is ethyl chloride?
-5 degrees C
What temperature is endofrost (propane/butane/isobutane)?
-50 degrees C
What temperature is dry ice (carbon dioxide snow)?
-78 degrees C
What fibres are stimulated when doing the heat test and what does this cause?
C fibres, dull pain of longer duration
What occurs in the pulp-dentine complex to produce a positive EPT?
an ionic shift in the dentinal fluid within the tubules causing local depolarisation and subsequent generation of an AP from an intact A delta nerve
When using the EPT on a molar tooth, where should the tip be placed?
MB cusp
What conducting medium is applied to the end of the EPT?
Prophy paste
Regarding an EPT, what can partial necrosis cause?
may get a positive result however only 1 root may contain vital nerve tissue
Why can teeth with acute alveolar abscess sometimes test positively with the EPT?
because the gaseous and liquefied elements within the pulp can transmit electric charges to periapical tissues (liquefaction necrosis)
In traumatic injuries, there can be temporary paraesthesia of the nerves, if vitality remains when should the pulp respond to EPT within normal limits?
30-60 days later
Why are sensibility tests not reliable on immature teeth?
contain fewer A delta fibres than mature teeth and myelinated nerves do not reach their maximum depth into the pulp until the apex has completed development
Describe the local anaesthetic sensibility test technique
using an infiltration anaesthetise tooth most posterior in suspected area. If pain persists move mesially and so on until pain disappears. If debating between upper and lower IANB can be given and cessation of pain indicates involvement of mandibular tooth.
What is sensitivity defined as?
the ability of a test to detect disease in patients who actually have the disease ie. ability to detect non-vital teeth
What is specificity defined as?
the ability of a test to detect the absence of disease. ie. ability to detect vital teeth
How is specificity calculated?
TN/TN+FP
How is sensitivity calculated?
TP/TP+FN
What is laser doppler flowmetry?
optical measuring method the detects presence of moving red blood cells within a tissue. Laser light can be transmitted to pulp by means of fibre optic probe placed against tooth surface.
What are the indications for use of laser doppler flowmetry?
pulp testing children
traumatised teeth
monitoring re-vascularisation of replanted teeth
differential diagnosis of periapical radiolucencies
Following trauma, what sensibility test would be recommended on an immature permanent tooth with an open apex?
Cold test
Following trauma, what sensibility test would be recommended on an immature permanent tooth with pulp canal mineralisation?
EPT
Following trauma, what sensibility test would be recommended on a mature permanent tooth with pulp canal mineralisation?
EPT
Following trauma, what sensibility test would be recommended on a mature permanent tooth with a patent canal space?
Cold, EPT, heat
