Endo Flashcards
What are the four principle to endo ?
- Respect the integrity of the pulp and the periodontal tissues by avoiding mechanics, and chemical trauma
- Protect vital pulp
- Provide RCT tho eliminate any source of infection
- Follow up
What is endo?
Branch of dentistry that deals with the aetiology diagnosis prevention and management of diseases of the dental pulp and their sequelae
What are the stages to endo?
Diagnosis Access Canal prep Canal medicaments Obturation Follow up
What type of bacteria cause endo lesions?
Aerobic and anaerobic but becomes more anaerobic with time and more gram negative
What type of relationship exist between the bacteria?
Symbiotic
Name the bacteria involved in endo?
Streptococci
Prevotella oralis
Porphyromonas
How do Bactria gain access to the root?
Deep carious lesion
Anchoresis
Perio
Trauma
What is the mantra for endo?
Cleans
Shape
Obturate
What is the aim of endo?
Provide a 3D hermitic apical and coronal seal
What lesion may we see adjacent to the tooth to indicate pulp deAth?
Sinus
What must we take before beginning endo?
Medical dental and social history
Full pain diagnosis
X-ray
What must you look at on the pre op X-ray?
- Large restoration or caries, previous pulp cap,
- pupal reaction, narrow canals, chamber, internal resorption
Pulp chamber: position of roof and floor and how much reparative dentine
Root canals: number of roots and canals, how much calcification, pulp,stones? And canal curvature
Any previous root filling, Periapical radiolucency
What is the apical war zone?
PMN
Macrophages
B and T cells
Plasma cells
What are the inflam mediators involved?
CLN
Complement
Lysozymes
Neuropeptides
What is the perical lesions caused by?
PLC
Prostaglandins
Leukotrienes
Cytokines
What must you assess with regards to the tooth that you are going to Do RCT on?
Look: Colour Caries Presence of sinus Erythema over apex
Touch:
Mobility
TTP
Tender to palpation
Invasive :
Vitality
Local perio
Radiograph to show pulp morphology
What is the first stage of endo once the assememt has been done? And what can you use for this?
Access
High speed burs for initial access and them slow speed eg tapered fissure/endo Z/Blunt ended/ or round burs
What is special about some of the ways the access burs are made?
They have long shanks and some have blunt ends (non cutting tip)
What is the diagnosis for the pulp following investigations?
Healthy
Reversible pulpitis
Irreversible pulpitis
Necrotic pulp
What are the requirements of the pre op radiograph?
Treatment tooth centrally located with at least 3-4mm peri Radicular tissue available and taken with film holder to minimise distortion
Second film taken at 15/20 degrees horizontal parallax
What is the purpose of the access cavity?
Removes the entire roof of pulp
Allows debridement
Allows access to the canals with straight line
Allows placement of temporary cement between visits
Conserved tooth structure but still achieve goal s
What shape should the access cavity be?
Non undercut
What is the shape of the access cavity determined by?
Position and number of pulp horns
How manu pulp horns does an incisor have?
3
How many pulp norms does a canine have?
2
How Many pulp horns does a premolar have?
2
Ovoid
What shale is the access cavity for molars?
Triangular
What size magnification does an operating microscope use?
X16
What size magnification do loupes provide?
X2 to 4.5
What can be used to locate canals?
Knowledge of anatomy Information from radiographs Magnification technqiue Trans illumination with white light Canal probe Fine endo instruments eg 6,8 Dyes Ultrasonic
What access problems may you come across?
Crown in situ so loss of directional sense
Obstruction within canal eg pulp stones, post crown, fractured instrument
How do you acces?
- Check depth from reference point to roof of pulp chamber
- Use tapered fissure bur to create outline in dentine
- Continue in depth until pulp chamber reached
- Apply rubber dam
- Remove roof of pulp using slow speed long shank bur Refine the cavity and cut on the out stroke to flare access
- Clear debris from chamber with excavators
- Irrigate with sodium hypochlorite
- Locate orifices if canal and check straight line access
What is the advantage of rubber dam?
Protects oro pharynx
Protects soft tissue From caustic material
Retracts soft tissue and tongue and improved access
Maintains clean dry and aseptic working environment
What is the next stage following access?
Measure the working length
How can working lengths be measured?
Tables of average length
Apex locator
Radiographs
What is the average length for the maxillary incisors and premolars from average value tables? What is the disadvantage of this?
Central: 23.70 Lateral: 22.10 Canine: 27.30 Four: 22.30 Five: 22.30
Dis: makes huge assumptions
How does an apex locator work?
Measure electrical resistance between an instrument in a root and an electrode attached to the oral mucosa
It passes a direct current through the tissue
What is the average value of the resistance at the apical tissus?
6.5kohms
How acurste are apec locates?
90%
What are the problems with apex locators?
Dentine debris can deflect from accuracy
Avoid use on wide canals and open apices
Remove excess fluid
Wet canals: absolutely ALmmachines only from pus, exudate, hyochlorote
Heavily restored teeth: all machines
Poor contact of lip electrode
What is the radiographic working length?
Measurement from fixed reference point kncisallt or occlusals to the radiographic Apex of the root minus 1mm
What is the working length?
Distance from a fixed reference point on the crown of a tooth to the terminus near the radiographic apex
What is the terminus?
Point where tooth naturally constricts where secondary cementum invaginates
Once you have got your working length what must you check?
Canal patency
How can we open the orifice of the canal?
Hedstrom
Gates glidden
SX protaper fils
How are Hedstrom files made?
They are machines from a round blank by cutting a spiral groove along the shank. This creates a sharp cutting blade to produce a file with an aggressive cutting action
What are the dis of Hedstrom?
Creates a lot of debris
Inflexible
How do you use gates gliddens?
Cut in out stoke
Start with largest one and work way down
What type of cutting tip do GG’s have?
Non cutting tip
How are GG’s manufactured?
So they fracture at the neck
What sizes of GG’s are there?
0.5 to1.5mm
How can you calculate the diameter of the GG?
In hundredths of mm
20(GG + 1) + 10
What is the process to orifice enlargement?
- Size 10k file passed to apical constriction 1mm from apex using watch winding to check canal patency
- Largest Hedstrom that passes 3mm into orifice is used with a rasping action cicrumfrentially around canal periphery and cut on out stroke
- Use progressively smaller hedstroms but DO NOT NEGOTIATE CURVE
What is the purpose of orifice enlargement?
Removes heavily infected material
Improves access to apical third
Improved irrigation
Reduces the effective curvature
How are the standards of some endo instruments monitored ?
ISO: international standards applied to endo files
What does ISO relate to?
Standardised sizing relating to diameter 1mm from tip of instrument and colour coded handles
Standard working length of 16mm
Standard taper of 2%
What length are the files made in?
21
25
31
How do you use K files?
- Small watch winding action at apex to create apical stop
- Two sizes larger then the first file that binds and this is you MAF
- Step back with progressively smaller files
- Recapitulate with MAF
When would the step back technqiue be used?
Large canals
Mostly anterior teeth
What instrumention techniques are thre?
Stepbac,
Modified Stepbac,
Crown down
How does the step back work?
Instrumentation of the canal starts at the terminus and works backwards to the coronal aspect
How does the modified step back work?
Coronal aspect is opened up first before creating terminal stop and flare backwards to first flare
How does the crown down technique work?
Instrumentation begins at the most coronal aspect towards the terminus
What are the filing techniques?
Balanced force Reaming Anti curvature Watch winding Longitindal circumferential
How do you instrument a curved canal with SS and NiTi files?
SS: watch winding and balanced force
NiTi: hand filing with balanced force and rotary filing
Outline the stages of modified step back
Access
Patency checked with 10k
EWL and CWL
Orifice enlargement using Hedstrom/GG
Create apical stop at CWL (MAF is 2 sizes up from first file that binds)
Watch winding with size 10 and 15 and blacked force with 20 above
Irrigate and recapitulate
Step back (second flare) 1mm shorter each time
What filing techniques can be used to create apical stop?
Balanced force and anti curvature
What are the advantages of the balanced force technique?
Superior shaping
File remains centrally within the canal
Less debris is pushed apically
What are the diasadvantes of the balanced force technique?
Needs copious irrigation and flute cleaning
What are the two phases to balanced force?
Power phase: engagement, this is when the place the file in canal until binds, advanced file by a clockwise rotation of 60 degrees
Control phase : cutting phase: apply apical pressure rotate file 120 degrees anticlockwise
What size k file do you use balanced force?
20+
What errors can arise in canal preparation?
Incomplete debridement Lateral perforation Apical perforation Blocked canals Ledging Apical zipping Elbow formation
How do apical zips arise?
Wrong rotation of the instrument
How do elbows form?
Inappropriate precurving
When is longitudinal circumferential filing used?
Large irregular shaped canals at the step back stage
What is the advantage of anti curvature filing?
Advantage: avoids strip perforation on inner curve or curved canal, uses a 3:1 filing ratio and need pre curved k files
Which is the disadvantage of anti curvature ?
Copious irrigation and recapitulate and careful of elbows
What are the ideal properties of root canal irritants?
Non irritant Bactericidal Dissolve organic material Remove in organic material, No staining to dentine Libricates instruments
What irrigants do we use in RCT?
Sterile saline
LA
Sodium hypochlorite
CHX
What percentage of sodium hyochlorote do we use?
0.5-5%
What are the advantages of sodium hypochlorite?
Antibacterial
Dissolves organic debris
Non irrigant to vital tissues
Which chelating agents do we use?
EDTA 15/17%
What is the effect of EDTA?
Breaks down inorganic debris
Lubrcates
Gets rid of smear layer when used with sodium hypochlorite
Effervescence with sodium hypochlorite
How does the crown down technique work?
We of
How does the crown down technqiue workB
Removes heavily infected material from the coronal pulp chamber and improves irrigation and reduced the effective curvature of the canals
Coronal and mid sections of the canal are opened first and then they only engage a small section of the canal
When are protaper files used ?
Small canals curved canals
What is the order for protaper files?
SX: Orange S1: purple S2: white F1: yellow ISO 20 F2: red ISO 25 F3: blue ISO 30
What is the cutting length of protwpers?
14mm
What is the maximum flute diameter for protwpers?
1.2mm
What are the advantages of protaoers?
Progressive taper design that improves flexibility and cutting efficiency
Fewer file changes needed
Engages smaller area of dentine this reduces torsional loads,mile fatigue, and potential for separation
Convex triangular surface which reduces contact between the file and the dentine
Greater cutting efficiency since balanced pitch and helical angles
Elasticity and shape memory
Progressive taper of 2-19%
T/F NiTi have two crystallographic phases?
T
Autensitic and martensitic
The phase change is stress induced
Which out of autensitic and martensitic is the daughter?
Martensitic
How much flexible is NiTI than SS files?
3-5
T/F there is decreased ledging and transportation with NiTi?
T
What is the sequence to protaper files?
- SX file clockwise and engage dentine until snug
- Disengage by rotating counterclockwise 45-90 with apical pressure e
- Rotate handle clockwise whilst simultaneously withdrawing to ensure removal of dentine
- Resstablish patency with size 10
- CWL and increase apical stop to size 15 and then 20 to create Glyde pathway
- S1
- S2
- Finishers
Which medicaments can be placed in the canal?
Chemical: beechwood creosol
Antibiotic/steroid
CaOH paste
Which antibiotic steroid paste formula is there?
1g Leadermix
30mg Demethylchlortetracycline (bacteriostatic)
10mg Triamcinalone acetonide
When should you use leadermix?
Actuatly inflamed vital pulp where Anlagesia for extirpation cannot be obtained
Insufficient time to embark on endo following pulpal exposure
What is usually the medicatment of choice?
CaOH
BP powder with 1:8 barium sulphate
Paste: hypocal and reogen
Life: catalyst paste only
What are the features of CaOH that make it ideal?
Hydroxide ion: pH12.5 which is bactericidal to wide group of organisms, effective solvent of organic debris, promotes hard tissue genesis, neutralises acids in areas of resorption, OH combines with lactic acid and stops action of dentinoclasts
Calcium ion needed to activate calcium dependant ATP reaction for hard tissue genesis from Krebs cycle
How do you place CaOH?
Spiral root filler
Hand file
Injection syringe
What are rh used ofnCaOH?
Pulp cap Internist medicatment Treatment of large Periapical lesions Root resorption Apexificatjon Root fracture and perforation
What are the common temp dressings?
Cotton wool and GIC or ZnO eugenol
What should the master GP relate to?
Master file
How can the master cone be too long?
Incorrectly calculated working length
GP too small and pushed through apex
How can the master GP be too short?
Incorrect working length
Filing debris has blocked terminus
Selected Master GP that is too long
What is the purpose of obturation?
To prevent microorganism from entering or re infecting the root canal
Prevent tissue fluids from percolating back into the root canal system and providing a culture medium for any residual bacteria
Obturation aims to provide?
A 3d coronal and hermetic seal to prevent microleakage
What is the smear layer?
Made from organic and inorganic debris and extends into tubules for 1-2 to 40 mincrons
May contain microorganism and creates an avenue for leakage microorganism
Acts as a substrate for microbial proliferation
How can you remove the smear layer?
17% EDTA with sodium hyochlorote
10-55% citric acid then sodium hypochlorite
Which materials we’re used for canal obturation?
Paste
Silver points
Cements
Amalgam
Which material are used now?
MTA
GP
What is the problem with silver points?
Single cone and relies heavily on sealer
What is GP made from ?
Transpolyisoprene
GP: 19-22%
ZnO: 59-75
Waxes, colouring agents and metal salts: 3%
What is the length of SX file?
19mm
What is the length of S1-F5?
21,25,31 mm
