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38 Cards in this Set

  • Front
  • Back
Access prep need to be:

no undercuts

smooth axial walls

all canals visible

funnel shaped

straight line access

safe irrigation

straighten out curves

disadvantages of traditional files

produce narrow canals

increasingly inflexible as they increase in size

canals are rarely an 02 taper

use a lot of instruments,

if continually rotated they will fracture

can easily create ledges

can push debris into the canal and cause blockages

very time consuming

NiTi File properties

super elastic metal

used in a continuous motion

have modified cutting edges to prevent binding in the canal

non cutting tips which allow the files to remain centred in the canal

have radial lands which prevents locking in the dentine

rake angle is usually negative or neutral

the grooves allows removal of debris

however do produce a thick smear layer

used for canal enlargement not negotiation

protaper file properties

triangular cross section, active cutting blades, blunt tip

shaper x file = 3.5-19% taper up to 9mm then 2% taper 10-14mm

shaper 1 file = 2-11% taper up to 14mm

shaper 2 file = 4-11.5% taper up to 14mm

contraindication for using rotary files

tight or sclerosed files,

very curved canals

s-shaped canals

apical hooks

canals with sharp elbows

if a glide path cannot be formed

advantages of NiTi files

less canal transportation


good deep shape

less debris extrusion


fewer files used

more predictable results

disadvantages of NiTi files

torsional and flexural failures and fractures

methods for determining working length

tactile feedback

paperpoint technique


electronic apex locator

Types of Apex



major apical constriction

minor apical constriction


problems with electronic apex locators

metallic restorations short circuit the system

perforation trigger a response

large canals can cause misreading

most common pathways for bacterial entry into the canal



exposed dentine

broken down restorations

reasons for placing an interim restoration

structural integrity

support for weakened cusps

coronal seal

rubber dam easy to apply

ideal cavity can be cut

no risk of leaking irrigants

a temp restoration will be better retained

more comfortable and functional for the patient

can be used as a core for an indirect restoration

why would you remove a crown before endo?

can thoroughly asses the underlying tissue

identify hidden pathology

better orientation

better coronal seal

main requirements of a temporary restoration

good coronal sela

easily removable

obvious difference between this and tooth tissue/interim restoration


why protect posterior teeth undergoing endo?

reduced tooth structure

access cavity

loss of marginal ridges

axial forces can flex cusps

non-axial forces are even more damaging

options for protecting posterior teeth

occlusal adjustment

cusp reduction and overlay

onlay/overlay indirect restoration

full crown

properties of irrigants

kills and removes bacteria

removes debris/nectrotic/inflamed tissue

removes dentine debris and smear layer

provides lubrication

obstacles in the way of irrigation

anatomical complexities

smear layer

fluid dynamics


resistant microbiota

smear layer consists of...

inorganic and organic substances,

odontoblast processes,


necrotic debris

it provides protection for bacteria

what kind of needle used to irrigate and why?

side venting size 27/30 gauge needle and luer lok syringe

stop locking into the canal and stops apical pressure

ideal characteristics of an endo irrigant

effective microbial action

non-irrigating to the periapical tissue

stable in solution

prolonged antimicrobial action

active in the presence of blood/proteins/serum

low surface tension

not interfere with periapical healing

not stain tooth tissue

not cause allergic reaction

completely remove smear layer

non toxic, non-antigenic, non-carcinogenic

no reaction with filling materials

easy to use


types of irrigant and strengths

NaOCl - 1.25%

EDTA - 17%

Chlorhexidine - 0.2-2%

Iodine potassium iodide - 2% iodine in 4% potassium iodide

hydrogen peroxide 3-5%

MTAD - 3% doxycycline, 4.25% citric acid

Photo activated disinfection

electronically activated water

NaOCl advantages and disadvantages


dissolves organic matter and biofilm, antimicrobial, affordable


minimally removes smear layer, reduces flexural strength of dentine, can cause allergies, toxic to vita tissues, corrodes metal instruments

EDTA Advantages and disadvantages

advantages: removes smear layer (use as penultimate rinse), non-toxic, eventually kills bacteria by starvation of metal ions

disadvantages: not bactericidal, overuse causes excessive removal of dentine

Chlorhexadine advantages and disadvantages

advantages: broad spectrum, cationic bibiguanide antiseptic, persistant activity, less toxic than NaOCl, no harmful effects to dentine

disadvantages: forms brown precipitate with NaOCl, no tissue dissolving effects, cannot remove smear layer, potential for allergic reaction

iodine potassium iodide advantages and disadvantages

advantages: broad antimicrobial spectrum, low toxicity, used in re-treatment

disadvantages: can stain dentine, not stable in presence of organic material, no tissue dissolving properties, unable to remove smear layer

hydrogen peroxide advantages and disadvantages

advantages: free radicals (OH*) destroy proteins, active against bacteria, yeasts, viruses

disadvantages : antimicrobial and tissue dissolving less than NaOCl, can release bubbles and cause emphysema, nolonger used as routine

MTAD advantages and disadvantages

Mixture of tetracycline, acid and detergent

advantages: borad spectrum antimicrobial, acid removed smear layer, no adverse effects on the tooth

disadvantages: less efficient on biofilm, more toxic than NaOCl, expensive, risk of bacterial resistance and tetracycline staining

reversible pulpitis signs and treatment

pain form hot, cold, sweet, short duration, doesn't linger, difficult to localise, no pa radiolucency, exaggerated response to vitality testing

treat the causative factor, tell them to take analgesics and pain will reduce

irreversible pulpitis signs and treatment

spontaneous pain that lasts for hours, triggered by heat, reliveed by cold, kept awake at night, ttp, pain radiates and can get worse

treatment: try and complete RCT

Hot pulps - alternatives to normal LA

regional anaesthesia, lignocaine and articaine, intraligamentary, intra pulpal, intraosseous, sedation

periapical periodontitis - signs and treatment

tender to percuss and palpate, swelling and reddening of the mucosa, to response to vitality testing, pain severe in function, can be constant or worsening, can be present for hours

treat by placing CaOH and bacteria tight seal and re-visiting

acute apical abscess - signs and treatment

swelling, pain on pressure, feeling of the tooth being elevated in the socket, mobility, lymphadenopathy, fever, malaise,

treat by drainage though incision, extraction or rct, give antibiotics at signs of spreading infection

cracked tooth - causes, signs, treatment

caused by mastication, bruxism, thermal cycling

signs - pain on chewing, sensitivity to hot and cold, difficult to locate pain, fracture line mesial to distal

treat with ortho band, replace restoration, rct if needed.

complicated crown fracture in permanent teeth treatment

pulp capping

partial pulpotomy


primary teeth pulp treatment

vital pulp = indirect pulp cap

no-vital tooth = pulpectomy

principles of electronic apex locators

2 or more currents are varying frequency are emitted, the impedence of the tissues surrounding the file is compared to the impedence of the buccal mucosa. when the values match then the file is deemed to be at the apex
why can it be difficult to anaesthetise in pulpitic cases

afferent nerve fibres from inflamed tissues have changing resting potentials, lowered excitability thresholds, difficult for la to prevent total nerve transmission, patients under stress have lowered pain threshold, accessory innervation