Description
In this collection we will review many important informations for dental students
Study Set Content:
Endodontics
Course Review
Enoch Ng, DDS 2014
Endo Diagnosis
-
Endodontic objective – absence of apical periodontitis (clinically, radiographically, histologically)
o
Prevention and treatment
-
Endodontic disease – from microorganisms from trauma, caries, and periodontal disease
o
Progression – pulpitis, periodontitis, abscess
-
Endodontic triad – debridement, sterilization, obturation
-
Diagnosis – art of distinguishing one disease from another
SOAP – subjective findings, objective findings, assessment (diagnosis), plan
-
Medical history
o
Bisphosphonates
o
Allergies – latex, medications
o
Uncontrolled diabetes
o
Infectious diseases
o
Infective endocarditis prophylaxis
o
Medications – immunosuppressives, corticosteroids, anticoagulants
-
Dental history
-
Chief complaint
o
Pain, swelling, loose tooth, broken tooth, discolored tooth
o
“Quotation marks” very useful in the record
-
History of present illness
o
Inception – when did problem/discomfort begin? Have you ever noticed it before?
o
Frequency and course – how often does this discomfort occur? Are the episodes more or less frequent
or about the same as when they first started?
o
Intensity – is the discomfort mild, moderate, severe? Patient’s verbal rating of pain from 0-10?
o
Quality – sharp, bright, dull, throbbing?
o
Location
McCarthy’s conclusions – patients experiencing periradicular pain (89%) can localize
painful tooth significantly more often than patients with pulpal pain w/o periradicular
symptoms (30%). Posteriors harder to localize than anteriors.
Can you point to the tooth that hurts/area you feel is swollen?
Were you ever able to tell which tooth was hurting?
Can you tell if discomfort is upper/lower or right/left side?
Does the discomfort start in one place and spread to another?
o
Provoking factors – do heat/cold, biting or chewing cause discomfort?
o
Duration – does discomfort linger when caused?
o
Spontaneity – does the discomfort ever occur all by itself?
o
Attenuating factors – does anything make the discomfort better/worse?
Hot/cold liquids
Sitting up/laying down, bending over
Analgesics
Endodontics
Course Review
Enoch Ng, DDS 2014
Diagnostic Procedures – order doesn’t matter, consistency does
-
Radiographic examination – state of pulp tissue, even if necrotic, cannot be determined radiographically
o
Caries
o
Past vital pulp therapy – direct and indirect pulp caps
o
Extensive restorations
o
Previous RCT – pulpotomy, pulpectomy, nonsurgical RCT, surgical RCT
o
Root canal calcifications – calcified canals, pulp canal obliteration (calcific metamorphosis), pulp stones
o
Lesions of endodontic origins
o
Internal (circular, continuous) vs external (non-uniform, irregular) resorption
-
Clinical examination
o
Visual Extraoral
Swellings, Lymph node exam, Sinus tracts
o
Visual Intraoral
Hard tissues – caries, discoloration, fractures, cracked teeth, vertical root fractures, occlusion
Soft tissues – swellings, sinus tracts, periodontal status
o
Diagnostic tests – (S = positive, NS = negative)
Percussion – apical inflammation
Test by digital (finger), then instrument handle
Horizontal and vertical vectors
Palpation – apical inflammation, swelling
Periodontal probings
I – furcation not open
II – can feel furcation, can’t go through it
III – can go through furcation
IV – can see through furcation
Vitality tests – electric pulp test, temperature tests
o
Aδ – sharp pain, low threshold, EPT and cold test
Not fully formed until 5y after tooth eruption
o
C – dull pain, high threshold, heat tests
True nociceptive nerves, resistant to necrosis
EPT – set rate no higher than 4, test on “normal” tooth first
Thermal tests – differentiate between reversible and irreversible pulpitis
Cold tests – test response (S, NS) and lingering (L, NL)
Lingers for ??? considered irreversible
o
Ice stick – 0
o
C, Not for full coverage teeth
Melting ice on adjacent areas may give false positive
o
Endo ice – -26.2
o
C, Tests 3-4 teeth per application
Spray for 3s from 5.0mm distance, shake off excess
Hot tests
o
Burlew wheel, Hot gutta-percha, Hot ball burnisher
Problems with these 3
Temperature can be raised 20
o
in 20s
Increases >20
o
can cause pulpal damage
Temperature no greater than 140
0
F to prevent irreversible pulpal injury
o
Elements/system B – system of choice for “hot” testing
Endodontics
Course Review
Enoch Ng, DDS 2014
Mobility
Transillumination
Sinus tracts
Record presence or absence
Trace with sterile 30 or 35 0.02 tapered gutta percha point
o
Can radiograph to ID associated tooth/areas
Selective anesthesia – very helpful when attempting to rule out an arch/referred pain
Anesthetize primary source of pain
o
Block vs infiltration
o
Mandibular vs maxillary anesthesia
Do NOT use PDL injection to ID source of pain
Direct dentinal stimulation
Used ONLY when all other test procedures have yielded equivocal results
-
Additional considerations
o
Referred pain
Pain in anterior from anterior tooth? Pain in posterior from posterior tooth?
Pain rarely referred across midline
Anterior teeth do NOT refer mandibular pain to maxillary, or vice versa
Posterior teeth CAN refer mandibular pain to maxillary, and vice versa
o
Maxillary sinusitis
Medical history – history of sinusitis, recent cold or flu
History of present illness – postural component
o
Cracked teeth
Erratic pain on mastication
Patient has trouble explaining complaint, radiographically inconclusive
Sometimes cold sensitive, NOT percussion sensitive
Long history of pain, treatment failed to resolve symptoms
o
Bradontalgia – tooth change from change in atmospheric pressure
Terminology – refer to diagnostic terminology handout
o
Apical – by the apex
o
Periapical – around apical portion of the rooth
o
Periradicular – surrounding the root
-
2 part diagnosis – pulpal and apical
Endodontics
Course Review
Enoch Ng, DDS 2014
Access Cavity Prep
Rubber Dam
-
Rubber dam required for all endo cases – standard of care
o
Protection of patient
o
Creates aseptic environment, infection control
o
Enhances vision, makes treatment more efficient
o
Retracts tissue, soft tissues are protected from laceration chemical agents and medicaments
o
Irrigation solutions confined to the operating field
o
Protects patient from swallowing aspirating instruments and/or materials
o
Generally, medium weight non-latex type
-
Rubber Dam Retainers
o
Anterior –#9 or #212
o
Premolars - # 0 or 2
o
Molars - # 14, 14A, 56
-
Dam Placement
o
Evaluate ability to isolate – oraseal caulking can be used to seal, prevent saliva from getting into access
o
Periodontal support
o
Restorability, caries, defective restorations/leaking margins
o
Crown lengthening
o
Cost/tx plan, consent
Access Prep
-
Objectives
o
Remove all caries, conserve tooth structure
o
Completely unroof pulp chamber, remove all coronal pulp tissue
o
Local all root canal orifices
o
Achieve straight line access to apical constriction or initial curvature of canal
o
Establish restorative margins to minimize marginal leakage of restored tooth
o
Consider multiple tooth isolation – short clinical crown, retainers not in way of radiographs, etc
-
Other Considerations
o
Until RD is in place, broaches and files CANNOT be used
o
All unsupported tooth/restorative structure must be removed
o
Radiographs may include off angle bitewings and Pas
Estimated access length
Endodontics
Course Review
Enoch Ng, DDS 2014
-
Laws of Symmetry
o
Law of Centrality – floor of pulp chamber always at center of tooth at level of CEJ
o
Law of Concentricity – external root surface anatomy reflects internal pulp chamber anatomy
o
Law of the CEJ – distance of external surface of clinical crown vs wall of pulp chamber is the same
throughout the circumference of tooth at level of CEJ
o
CEJ – most consistent repeatable landmark for locating pulp chamber
o
1
st
Law of Symmetry – except for Mx molars, canal orifices are equidistant from line drawn mesio/disto
across center of pulp chamber floor
o
2
nd
Law of Symmetry – except for Mx molars, canal orifices lie on line perpendicular to above line
o
Law of Color Change – pulp chamber floor always DARKER than the walls
o
1
st
Law of the Orifice – orifices of the canals ALWAYS located at junction of walls and the floor
o
2
nd
Law of the Orifice – orifices of the canals ALWAYS located at the angles in the floor-wall junction
o
3
rd
Law of the Orifice – orifices of the canals ALWAYS located at terminus of roots developmental fusion
lines
-
Access Preparation
o
Use a #2, 4, or 6 friction grip round bur
o
Endo Z bur (tapered safe ended bur)
o
Sharp endo explorer
o
Magnification
o
Long shanked low speed burs
o
Ultrasonics, transillumination, dye staining, irrigation and interim radiographs
Accessing Teeth
-
Mx Incisors – always 1 root 1 canal
o
Young patients = triangular, older patients = ovoid
-
Mx canines – always 1 root 1 canal
o
Ovoid
o
In middle 1/3 of lingual surface
-
Mx Premolars
o
Outline form ovoid facial/lingual
o
Mesial concavity at CEJ
o
When 2 canals are present, under B and L cusps
-
Mx Molars
o
Outline form triangular in mesial ½ of tooth
Base = facial, apex = lingual
o
Oblique ridge left intact (usually)
o
MB canal slightly distal to MB cusp tip, broad B/L, may have MB2 canal
MB2 canal 1-3mm lingual to MB1, slightly mesial to line drawn from MB1 to PC
o
DB canal distal and slightly lingual to main MB canal, in line with buccal groove
o
P canal slightly distal to ML cusp tip, largest canal
-
Mn incisors – 25-40% have 2 canals
Facial easier to locate, generally more straight
Lingual often shielded by a lingual shelf
o
Outline form, shape, and access similar to Mx incisors
Endodontics
Course Review
Enoch Ng, DDS 2014
-
Mn canines – 30% have 2 canals
o
Ovoid
o
Middle 1/3 of lingual surface
-
Mn Premolars – 25% have 2 canals
o
Ovoid B/L
o
Buccal to central groove
-
Mn Molars – 30-40% chance 2
nd
canal in distal root
o
Rectangular
o
MB canal slightly distal to MB cusp tip
o
ML canal orifice in area of central groove, slightly distal compared to MB canal
Errors in Access
-
Inadequate preparation
-
Excess removal
Endodontics
Course Review
Enoch Ng, DDS 2014
Instruments and Materials
Medical Emergencies
o
Aging patient population
o
More medications
o
Dental pain/infection
-
Epi-pen = 0.3mg (Epi-pen Jr. = 0.15mg)
o
Check window for expiration
o
Take off blue cap
hold orange tip against thigh
syringe auto injects within 10s
-
Nitrates
o
Prime pump first – do NOT shake)
o
Spray under tongue – do NOT swallow, expectorate, or rinse for 5-10min
Can be used every 3-5min for first 15min
o
Don’t forget to check BP and call 911
-
Albuterolol
o
Shake well and take off cap
o
Tell patient to breathe out and take a deep breath as they inhale spray
o
Hold breath as long as possible
o
Repeat if needed
-
Low blood sugar
o
Glutose 15
use before patient is unconscious
o
Rip off tip and squeeze entire contents into mouth, then swallow
-
Other medications
o
Diphenhydramine (antihistamine)
o
Aspirin
Prescription Writing
-
Ancient prescriptions found in both Chinese and Egyptian writing
o
Fill in patients name
o
Requires date – controlled substance prescriptions have a time limit
o
Rx symbol (take though) – list drug and strength here (trade/generic name, __mg)
o
Disp – number of tablets patient should receive
o
Sig (mark thou) – directions for patient
o
Write in number of refills
o
Sign prescription and include phone number
o
Write DEA# (do NOT have this printed on prescription pads) for controlled substances
Endodontics
Course Review
Enoch Ng, DDS 2014
-
Common Abbreviations
ac – before meals
hs – at bedtime
pc – after eating
prn – when needed
stat – immediately
ut dict – as directed
po – by mouth
pr – rectally
c – with
s – without
qd – every day
qod – every other day
bid – twice daily
tid – 3x daily
qid – 4x daily
g/gm – gram
gr – grain
tbsp – tablespoon
tsp – teaspoon
cap – capsule
gtts – drops
o
Write clearly
o
Use metric and zeroes with decimals
o
Include reminder of intended purpose of medication with directions (ex:// for pain)
o
Do NOT use abbreviations
-
Narcotics
o
Schedule 1 – marijuana, heroin
o
Schedule 2 – Percodan, Tylox
o
Schedule 3 – Vicodin
o
Schedule 4 – valium, Darvocet N
o
Schedule 5 – anti-diarrhea meds, codeine containing cough syrups
Schedule 2 – most be written prescription (except emergencies) and only enough for 24h period
Must include written copy to dispenser, no refills allowed
Schedule 3-5 – 6month time limit, NMT 5 refills
-
Completing Prescriptions
o
Print from axiom, have instructor sign
o
If scheduled drug, BNDD number needed
Pulp and Periradicular Tissues
-
Dental Pulp – loose CT with unique features
o
Rigid, noncompliant environment
o
Lacks collateral circulation
-
Pulpal pathosis
o
Irritants – microbial, chemical, mechanical
-
Periradicular pathosis
o
Preceded by pulpal pathosis
o
Periradicular lesions result from bacteria and their byproducts
o
Apical periodontitis is BOTH protective and destructive
-
Nonsurgical Root Canal Treatment
o
Clean and shape root canal system
Debridement of root canal system
Enlarge and shape canals to facilitate obturation
Create apical seat to contain obturating material
o
Obturate root canal system
Create bacterial/fluid tight seal along length of root canal system from coronal to apex
Use gutta percha, sealer, definitive coronal seal
o
Maintain health/promote healing and repair of periradicular tissues
o
Alleviate symptoms/prevent future adverse clinical signs/symptoms
Endodontics
Course Review
Enoch Ng, DDS 2014
Examination
-
Etiology
o
Carious lesion causes bacterial infection, leading to periapical granuloma
-
Diagnosis and treatment plan
-
Case selection and referral
-
Treatment
-
Prognosis
Sinus Tracts
-
Is NOT a dental fistula
o
Fistula = communication between 2 internal organs/organ and body surface
o
Sinus tract = tract leading from area of inflammation to an epithelial surface
-
Fairly evenly distributed between Mx and Mn (of 758, 400 Mx and 358 Mn)
o
1600 teeth with PA lesions, 136 had sinus tracts (8.5%)
87.5% open to facial side
5.8% open to palatal
5.1% found extraorally
1.5% perforate Mn lingual sulcus
-
In Monkeys, need >100 days to form sinus tract
o
100-200days = 46% of openly exposed teeth develop sinus tracts (none epithelial lined)
o
>200 days = 4/7 sinus tracts lined by epithelium
-
Dentoalveolar sinus tract – usually route of drainage from inflammatory PA lesion
o
Follows path of least resistance through bone, periosteum, and mucosa
o
Usually close to source of drainage, but may be some distance as well
Radiography
-
Aids in diagnosis
-
Visualization of anatomy
-
Used for estimating working length
Rubber Dam
-
Potential leakage
o
Subgingival caries
o
Fractures
o
Defective restorations
o
Open margins
Endodontics
Course Review
Enoch Ng, DDS 2014
Hand Instruments
-
Endo explorer – long tapered tines at either a right or obtuse angle (facilitates locating canal orifice)
o
Very stuff, not for condensing gutta percha
o
Should not be heated
-
Spoon excavator – long shanked and used to remove caries, deep temporary cement, or coronal pulp tissue
o
Has both right and left hand orientated positions
o
Should not be heated
-
Hand files – usually 21mm, 25mm, or 31mm in length
o
Spiral cutting edge of instrument is 16mm long
Diameter increases by 0.02mm per running length mm
D
0
at tip, D
16
at end of spiral cutting edge
o
Tip angle = 75
o
+15
o
o
Color code – different files for each diameter
Each diameter increases by 0.05mm up to size 60
Each diameter increases by 0.10mm from size 60-140
o
K-files – designed with cutting, partial cutting, and non-cutting tips
Glides file through canal and aids in canal enlargement
o
Hedstrom – designed for cutting and enlarging canals
Cutting edge is inclined backwards
Ground from stainless steel wire
o
Gates Gliddens – designed for cleaning and enlarging coronal 1/3 of pulp canal
-
Finger ruler
-
Working length file – should end 1mm from root apex, just coronal to apical constriction
-
Irrigating agent – sodium hypochlorite (bleach)
o
Adjunctive equipment
o
Irrigating needle
o
Chelator and lubricant
Use of EDTA for extended periods may be detrimental to dentinal tubules
Evaluation of Canal Preparation
-
Cleaning
o
Glassy smooth walls
o
Elimination of intracanal debris
-
Shaping
o
Proper canal size/taper
o
Apical preparation determination
-
Drying
o
Canal is dried with paper points
Endodontics
Course Review
Enoch Ng, DDS 2014
Obturation
-
Standardized gutta percha
-
Finger spreaders
o
Size = medium fine, fine
o
Composition = stainless steel, nickel titanium
-
Sealers (ZOE)
o
Roth’s sealer
o
Grossman’s sealer
-
Master Cone Radiograph
o
Sealer
o
Master cone
o
Accessory cones
o
Corrected working length
-
Obturating machines
o
9-11 heated plugger
o
System B
220
o
F – making post space
250
o
F – searing at orifices
Can also be used for gutta percha removal
-
Cotton pellet – covers access prep
Restoration
-
Temporary – cavit/IRM double seal, glass inomer
-
Definitive – composite, amalgam
-
Final radiograph assessment
o
Obturation – length, density, taper, coronal termination
o
Thickness of temporary
o
Compare against recall radiographs
Summary
-
NSRCT – predictable procedure with appropriate diagnosis and treatment planning
-
Tooth retention from NSRCT preferred treatment for periodontally stable restorable teeth
-
Better to preserve natural dentition than extraction/implant
Endodontics
Course Review
Enoch Ng, DDS 2014
Cleaning and Shaping the Root Canal System
-
Debridement – removal of irritants (bacteria, tissue, etc) from canal system
-
Chemomechanical – instrumentation and irrigation
-
Cleaning – ideally instruments contact and plane walls to loosen debris
o
NaOCl – dissolved organic matter, destroys bacteria
o
Irrigants – flush loosened/suspended debris/sludge from canal space
Irrigation
-
Lubrication, flush debris from canal, disinfection, tissue dissolution, removes smear layer
-
NaOCl – oxidative action on sulfhydryl groups of bacterial by HOCl
o
Bactericidal - inhibits enzymes, disrupts metabolism, causes cell death
NaOCl + H
2
O
NaOH + HOCl
HOCl = active biocide, dissolves organic tissue
o
5.0% highly toxic compared to 0.5%
-
Technique – syringe with irrigating needle
o
Requires safety glasses – can damage tissue, ruin clothing
o
Rubber dam isolation with seal (oraseal)
o
Passive and slow injection of solution into canal
Never force needle into canal, closer to apex = greater risk of injury
o
Files can carry irrigating solution further into canals
Capillary action of smaller diameter canals causes solution retention
Excess solution aspirated away with needle
o
Frequent irrigation = less debris and less apical blockage
-
Ideal Irrigant
o
Provides lubrication during instrumentation
o
Flushes debris from canal, removes smear layer
o
Dissolves organics in fins and isthmi, bactericidal
o
Low cytotoxicity
Dry vs Wet Instrumentation
-
Dry instrumentation
o
Apical extrusion of material negligible
o
More difficult to instrument canals – easier to plug apex with debris
o
Instruments more likely to jam and separate
-
Wet instrumentation
o
Apical extrusion dependent on canal length and file size
o
Less difficult to instrument canals
o
No instrument separation
-
Tissue Dissolution
o
Solvent action limited by surface contact, volume, and exchange of solution
Amount of organic matter
Frequency and intensity of mechanical agitation (fluid flow)
Available surface area of free or enclosed tissue (larger surface area = faster dissolution)
Endodontics
Course Review
Enoch Ng, DDS 2014
Bleach Toxicity
-
Toxic effect is 10x greater than antimicrobial effect
-
NaOCl cytotoxic to all but heavily keratinized cells
o
Very caustic, nonspecific agent – serious consequences from apical passage of NaOCl
-
Apical passage of NaOCl
o
Excruciating pain for 2-5min
Immediate swelling with spread to surrounding CT
Profuse bleeding either interstitially or intraorally throughout root canal system
o
Severe pain replaced with constant discomfort
Potential for permanent paresthesia
-
Treatment
o
Alleviate swelling with cold packs, warm saline soaks for following days
o
Pain control with LA and analgesics
o
Rx antibiotics – prevent spread of primary infection, increase susceptibility of secondary infection
o
Reassure patient
Smear Layer
-
NaOCl does NOT remove smear layer
-
REDTA DOES remove smear layer leaving no debris behind
-
NaOCl and RCPrep (EDTA + 10% urea peroxide + Carbowax) – smeared surface with more superficial debris
Difficulties with Instrumentation (Case selection)
-
Pulpal space
o
Calcification
o
Chamber size and shape
o
Orifice size and shape
o
Canal size and shape – may be very complex
Canals may join, separate, and differ in length
Electronic Apical Locator may be helpful
o
Number of canals
-
Root morphology
o
Curvature
Dilacerations
Long roots
Recurvature
o
Length
Long
Short
-
Occlusal Access
o
Looking for MB2 on Mx molars
o
Large enough to:
Visualize pulpal floor
Illuminate pulpal floor
Visualize subpulpal groove map
Develop straight line access
o
Usually requires removal of dentin shelf on mesial wall
Endodontics
Course Review
Enoch Ng, DDS 2014
Cleaning and Shaping
-
Continuously tapered form that holds filling material within the canal
-
Maintains original anatomy and conserves root structure
-
Maintain position of apical foramen without over-enlarging
-
Shaping facilitates cleaning
o
Allows irrigant access
o
File shape, irrigant cleaning
-
Small file (scout access)
-
Straight line access – may require coronal flaring
-
Enlarge to size 20 for estimated working length (minimal file size)
-
Irrigate
Gates Gliddens
-
Side cutting
-
Used for straight portion of canal
-
Used serially and passively with successively smaller sizes at greater depths
-
Used to brush away restrictive dentin and provide straight line access
-
Irrigate after each GG use
-
Cutting head diameters
o
#2 – size 70
o
#3 – size 90
o
#4 – size 110
Shaping and Access
-
Coronally, prepare AWAY from the furcation
o
Be aware of danger zones
Mesial concavity of mesial root of Mn molars
Distal wall of MB root of Mx molars
-
Anticurvature techniques
o
Precurve files
o
Instrument with pressure towards curve and coronally
o
Balanced force hand instrumentation
-
Checking canals
o
CWL – usually #20 file, may be larger
o
MAF – largest file used at corrected working length
o
May want to use different files (K-files and hedstroms) to differentiate between canals in radiograph
-
Improving cleaning
o
Combining both hand instrumentation and rotary
-
Apical Foramen Resorption – natural constriction may be destroyed
Set working length shorter = 1.5mm
May be difficult to obtain apical seat
o
Apical stop – MAF and next smaller file do not go beyond working length
o
Apical seat – MAF does not go beyond working length, but next smaller file does.
Resistance with smaller file is felt
o
Open Apex – MAF goes beyond working length, no resistance is felt by smaller file
Endodontics
Course Review
Enoch Ng, DDS 2014
Step Back Preparation
-
Hand instruments – enlarge canal 3 file sizes larger than first file that bound at corrected working length
-
Each step back is 0.5mm shorter, but 1 file size larger
o
Irrigate, recapitulate, irrigate, work with next step back file
o
Recapitulation is always MAF size set to corrected working length
-
Access
instrumentation
o
ID canal orifices, scout coronal 2/3
rd
of canal with #10 file
o
Scout with Gates Gliddens and flare orifice – straight line access allows for file entry without deflection
#2 GG 6mm into orifice
#3 GG 3mm into orifice
-
Minimal file for estimated working length should be a #20
o
For >1mm difference between EWL and CWL, take a new radiograph
-
Enlarge to MAF (usually at least #35) at CWL
o
Step back preparation, 0.5mm steps
o
Irrigate and recapitulate between each step
-
Place MAF at corrected working length for MAF radiograph
Pre-Obturation Evaluation
-
Glassy smooth walls
-
Canal clean of dentin and irrigant
-
Spreader penetrates to 1mm from CWL
-
Canal shape reflects natural root shape
-
Accurate ID of apical foramen
Common Errors
-
Ledge formation
o
Caused from uncurved file short of CWL gouging dentin, creating ledge blocking file from getting to CWL
o
Corrected by bending file tip 45
o
to tease it past the ledge
-
Transportation of apical canal
o
Non-precurved file can straighten a curved canal, possibly causing an apical perforation
-
Strip perforation
Cervical portion of file straightens canal in multirooted teeth
Communication on furcal side of root
o
Prevented by good straight line access
Avoid furcation region of canal when filing
Use smaller file sizes in very curved canals
-
Separated instruments
o
Prevented via discarding worn instruments
o
Avoid binding instruments in canal
o
Always instrument wet/irrigate
-
Canal blockage
o
Prevented via copious irrigation/recapitulation, not instrumenting on dry canal, don’t force files down,
removing materials that may fall in and block canal (amalgam, IRM, etc), using files sequentially
o
Cleaned with a small file at CWL
-
Overinstrumentation (beyond apex)
o
Prevented via an accurate CWL before instrumentation with larger files
Endodontics
Course Review
Enoch Ng, DDS 2014
Radiography
-
Diagnosis/Case Selection Aid – # of roots/canals, curvatures, calcification, hard/soft tissue alterations
-
Treatment Process Aid – EWL/CWL, localize difficult to find canals, determine relative position buccolingually
-
Aid in evaluating patient’s response to treatment
Endodontic Radiographs
-
Periapicals – diagnostic radiographs, working radiographs, post-op radiographs
-
Bitewings (vertical) – RESTORATIVE ASSESSMENT, caries ID, location of pulp chamber, vertical defects
-
Pan, occlusal, CBCT – difficult diagnosis, presurgical treatment planning for assessment of vital structures
-
FMX – history of teeth (restorations, PA lesion progression, etc)
Diagnostic Radiographs
-
Evaluate difficulty of case (case selection)
o
Chamber and canal morphology
Calcified or obliterated chamber/canals, pulp stones
Internal root resorption
o
Root morphology
Length, curvature, recurvature
Number, fused roots, possible C-shaped roots
External root resorption
o
Crown, root, or alveolar fractures
o
Previous endo access/treatment
Perforations, separated files, blocked/ledged canals
o
Periodontal bone loss, periapical pathosis
o
Proximity of anatomic structures
Sinus, mandibular canal, mental nerve
o
Ease of exposing radiographs on patient
Small mouth, large tongue, shallow palate
-
The more info, the better
o
Case selection, anticipate anatomy, anticipate problems with isolation
o
Fast break – indicates broad root canal has split into 2 smaller roots
o
Bullseye – indicates root apex has curved either straight buccal or straight lingual
Radiolucent lesions of endodontic origin
-
Trace PDL from coronal to apex outlining root end
o
Intact lamina dura, uniform PDL
-
Normal
widened PDL
apical lesions
large lesions
o
Loss of lamina dura, hanging drop of water appearance, doesn’t shift from apex in off-angle radiograph
o
Destruction of cancellous bone may not be seen
Only seen on radiograph when cortical plate is affected
-
Pulpal pathosis may not be differentiated on radiograph
o
Vital and necrotic pulps cast the same image on radiographs
o
Tissue in pulp space looks the same regardless of if it is:
Normal
Reversibly/irreversibly inflamed
Necrotic
Endodontics
Course Review
Enoch Ng, DDS 2014
-
Apical diagnosis cannot be distinguished solely by radiographic interpretation
o
Metastatic cancer, periapical cemento-osseous dysplasia, periapical cyst/granuloma all look the same
Only PA cyst/granuloma requires RCT (should provide no response to testing)
-
Interpretation of radiographs often misleading
o
47-73% agree between observers
o
75-83% agree for the same observer seen at different times
Working Radiographs
-
Radiographs for monitoring treatment procedures
o
For orientation on access – use bitewings to gauge depth of the pulp
-
Displays relationship between endodontic instruments/materials to apical portion of root
o
If you need to change working length >1mm, take new radiograph
-
Locating canals – a root will always have a canal
o
Canals may be small and difficult/impossible to locate
o
If single canal, will be positioned in center of the root
o
If canal is skewed off center, another canal is usually present
-
Evaluating cleaning and shaping, obturation
o
MAF – largest file cleaned to, placed in canal for radiographic film
-
Evaluating healing
o
Restitution of normal tissue structures
o
Disease can persist in the absence of signs/symptoms – radiographs essential for evaluating apical
response to treatment
-
SLOB rule – the canal that is closer to the side of the radiograph corresponding to the same off angle shot is the
lingual canal, and vice versa
o
Still requires direct straight shot for comparison as off angle shots have distortion
-
Maxilla (SMM)
o
Anteriors – straight shot
o
Premolars – mesial shot 20
o
o
Molars – mesial shot 20
o
4 canal molar – mesial shot separates MB1 and MB2, straight and distal shots superimpose them
-
Mandible (DMD)
o
Incisors – distal 20
o
o
Canines and Premolars – mesial 20
o
o
Molars – distal 20
o
Endodontics
Course Review
Enoch Ng, DDS 2014
Radiographic Techniques
-
Paralleling technique
o
Best definition and reproducibility, least distortion
o
Object and film parallel and central beam passes through them perpendicularly
-
Angle bisecting technique
o
Harder to reproduce, some distortion, more superimposition of anatomic structures
o
Film placed directly against tooth without bending film
o
Central beam directed perpendicularly to imaginary line bisecting angle between tooth and film
-
Film holders
o
Diagnostic radiographs – XCP instruments
o
Treatment radiographs – hemostat
Film placement is easier
Hemostat aids in cone alignment
Film held securely in place, less likely to slip
Always place “dot” on film to coronal part of tooth (won’t impose over roots)
Endodontic Radiography Limitations
-
Radiographs give 2D shadows of 3D objects – require off angle radiographs to see 3
rd
dimension
o
Maxillary anteriors do NOT require off angle radiographs (only 1 canal)
o
Varying horizontal angulation allows for appreciation of 3
rd
dimension
-
Vertical angulation
o
Increasing causes foreshortening of images
o
Decreasing causes enlongation of images
Radiographic Sequence
-
2 diagnostic/pre-Op radiographs
o
1 straight on and 1 off angled (except Mx anteriors)
o
Bitewings should be taken if there is extensive decay/questionable restorability
-
1 working length radiograph
o
If adjustment needed is >1mm, take new radiograph
-
1 MAF radiograph
o
Has largest working length file used at corrected working length inside canal
-
1 Master Cone radiograph
o
If adjustment needed is >1mm, take new radiograph
-
1 Pre-sear radiograph
o
Check for dense fill and no voids
o
Last chance to make changes prior to sear off
-
2 Post-op radiographs
o
1 straight on and 1 off angled to evaluate treatment
-
For Mx anteriors, a 6 mount is used (only 1 pre-op and 1 post-op)
-
For all other teeth, an 8 mouth is used
-
Radiographs are mounted left to right before starting next row
o
Radiographs are mounted in descending order of list above
-
Date each individual radiograph
Endodontics
Course Review
Enoch Ng, DDS 2014
Obturation
-
Eliminates leakage from oral cavity or apical tissues into canal system
-
Seals within the cavity any irritants that are not removed during cleaning/shaping
Influence on prognosis
o
Poorly obturated teeth are usually poorly prepared
-
Absence of pre-treatment PA lesion
-
RCT without voids
-
Obturation within 2mm of apex
-
Adequate coronal restoration
When to Obturate
-
Asymptomatic patient
-
Temporary filling is intact
-
Canal is prepared properly
-
Canal is dry or can be dried
-
Prefer to obturate on a different day than instrumenting – allow for healing to asymptomatic state
Obturation length
-
Ideally at minor constriction (CDJ)
-
Usually 1mm from radiographic apex (based on studies relating major foramen to apex and minor constriction)
-
Extrusion of obturation material decreases healing prognosis and may result in patient discomfort
-
Obturation shorter than 2mm from apex may slow healing, likely from remnant infected tissue left in that 2mm
-
Overfill – total obturation of canal but excess material extrudes out beyond apical foramen
-
Overextension – canal is NOT adequately sealed and material extrudes beyond apical foramen
Inadequate obturation
-
Long obturation causes
o
Excessive instrumentation beyond apex
o
Excessive penetration of compacting instrument
o
Excessive force during obturation
o
Resorptive defect, perforation, strip perforation, zip
o
Master cone too small
-
Short obturation causes
o
Dentin chips
o
Ledged canal
o
Curved canal
o
Master cone too large
o
Improper 3D shaping of canal in apical to middle third
Endodontics
Course Review
Enoch Ng, DDS 2014
Obturation preparation
-
Smear layer – cutting debris of mineralized collagen, odontoblastic process remnants, pulp tissue, and bacteria
that is burnished over dentin surface
o
1-2um thick
o
Can penetrate up to 40um into dentin tubules
o
Can block penetration of sealer into tubules
-
Smear layer removal – irrigation
o
Irrigation with 17% EDTA (chelator) – removes inorganic part of smear layer
o
Irrigation with 3% NaOCl – removes organic part of smear layer
-
Drying the canal
o
Aspiration after irrigation
o
Paper points
Comes in Fine, Medium, Coarse or Tapered to fit final preparation
Let paper point sit in canal for a few seconds to wick moisture
Measure paper points to not induce bleeding or apical inflammation
Obturation materials
-
Ideal requirements
o
Easily introduced, easily removed
o
Liquid/semisolid and becomes solid, seals laterally and apically, does not shrink
o
Impervious to moisture, bacteriostatic, sterile/sterilizable
o
Does not stain tooth, doesn’t irritate apical tissues, radiopaque
-
Historical materials
o
Silver points
Non-adaptable to canal
Can corrode – releases toxic byproducts into apical tissues
Difficult to remove – post space or retreatment
o
Pastes
Quick to use
Lacks length control – difficult to avoid overfill
Unpredictable/inconsistent seal
Shrinkage of material
Some have paraformaldehyde and arsenic
-
Gutta Percha – trans-isomer of polyisoprene (rubber is cis-isomer)
o
Contains
Zinc oxide (59-75%)
Gutta percha (19-22%)
Waxes, antioxidants, coloring agents, metallic salts
-
Advantages
-
Plasticity, ease of manipulation and removal
-
Minimal toxicity
-
Radiopaque
-
Disadvantages
o
Lack of adhesion to dentin
o
Significant shrinkage on cooling
2 distinct crystalline states – alpha and beta
Heating of beta phase (37
o
C) causes structural change to alpha state (42-44
o
C) and then to
amorphous state (56-64
o
C), with significant shrinkage when returning to beta state
Compaction on cooling is necessary
