Endodontics Materials Flashcards
1
Q
Name the 8 functions of endodontic irrigants?
A
Lubricate files to facilitate passage into canalWet canal walls and flush debrisContain any dentinal shavings in suspension so facilitating their removal from canals (prevents apical impaction of debris)Facilitate dissolution of organic materRemove smear layerAid cleaning of area inaccessible to mechanical cleansing methodsDisinfect RCSNeutralise endotoxins
2
Q
Name the 2 groups of endodontic irrigants?
A
Clean and expose bacterial contaminatesUsed to disinfect RCS
3
Q
Name 2 irrigants for cleaning?
A
EDTACitric acid
4
Q
What is the definition of citric acid?
A
Chelating agentRemoves calcified tissue and detach biofilms from root canal walls10-50%
5
Q
What is the definition of EDTA?
A
Synthetic aa or Na salt of EDTAethylenediamine tetra-acetic acidDemineralise and soften root canal wall dentine by 20-50umNeither cidal or staticKill bacteria by starving from metal ions (chelates metal ions)Non-toxicNon-corrosiveNot effective against smear layer alone15-17%Never mix with NaOCl
6
Q
Name a commercial product of EDTA?
A
ENdo-Solution EDTA Cerkamed dental-medical
7
Q
What is the function of EDTA gel?
A
Coat endodontic filesLubricate and removes smear layer making canal prep easier and fasterIncreased viscosity is better for holding debris in suspension
8
Q
What is the definition of EDTA gel?
A
Contains carbamide or urea peroxide causing effervesceElevator action helps to remove debrisBubbles when in contact with NaOClOxygen kills anaerobic bacteria
9
Q
Name a commercially available EDTA gel?
A
Glyde File PrepDentsply MailleferEDTA + carbamide peroxide
10
Q
When should you not use chelating materials?
A
Initially to negotiate canals as a false can may be cut iatrogenically
11
Q
How should you use chelating materials within the root canals?
A
Thoroughly washed from RCS as retention will continue softening the dentineAre self-limitingChelating + disinfecting irrigantProvides a cleaner surface
12
Q
Name 4 types of irrigants for disinfection?
A
NaOClIodine potassium iodineChlorhexidineOther potent phenolic disinfecting agentsHigh bactericidal concentrations close to toxic dose
13
Q
What is the definition of NaOCl?
A
Potent organic tissue solvent that is proteolytic and dissolves necrotic organic materialReleases free CL which has bactericidal effectsCl breaks peptide bonds dissolving proteins into aasAas degraded by hydrolysis by chloramine molChloramines are antibacterialOxidising and hydrolysing agentpH> 11No effect on smear layer (Ca)High pH denatures proteinsHydroxyl ions damage bacterial lipid and membranes + DNA
14
Q
Explain how to use NaOCl?
A
Breaks down components during useMust be replaced as i loses its efficacyDwell time of at least 30 minsBiofilm must be disrupted to reach bacteriaCanal must be flushed long after canal prep has ceased for this disinfectant to be effective
15
Q
What are the components of the NaOCl solution?
A
No diff between 0.5-5% solutions for antibacterial effectsBut efficiency of weak solutions decreases rapidlyHigh conc disinfecting process is faster, untoward damage can occur, as it is more toxicMore effective if solution is warmed, as more Cl is released
16
Q
What are the characteristics of NaOCl?
A
High surface tension than water, so does not wet canal wellWalls are not fully covered and the full biofilm may not by disruptedHigher conc = thicker solNot effective at killing all microorganismsEnterococcus faecalis can’t be killed
17
Q
When using NaOCl, what should you be wary about?
A
Bleaching clothesUnpleasant tasteIrritant to eyes, skin and oral mucosaBleaching will lighten any stained tooth tissue
18
Q
Name 2 commercially available NaOCl?
A
Parcan Sol (Septodont) 3%Chlorax (CerKamed Dental-Medical) 2% or 5.25%
19
Q
Why is Chlorhexidine digluconate better than NaOCl?
A
Kills microorganisms that NAOCl can’tSafer
20
Q
Explain how chlorhexidine digluconate works?
A
Binds to hydroxyapatite on the root canal wallsUsed as final soakGood substantivity of about 12 hrs after application
21
Q
What reaction occurs between Chlorhexidine digluconate and NaOCl?
A
Acid-base reaction seen with NaOCl forming an insoluble precipitate 4-chloroanilineStains dentineCarcinogenicDifficult to remove (can block canals)Can be overcome by irrigating with sterile waterCHX breaks down when heated to form PCA
22
Q
Name 2 commercially alleviable chlorhexidine digluconate products?
A
R4 (Septodont) 20% in denatured alcoholGluco-Chex 2.0% (Cerkamed Dental-Medical)
23
Q
Name 2 forms a chlorhexidine digluconate gel?
A
Hibiscrub (Regent Medical) 4%Gluco-Chex 2.0% Gel (Cerkamed Dental-Medical)
24
Q
What is the definition of Iodine Potassium Iodide?
A
Organic and releases iodineIodine is a potent antibacterial agent with broad spectrum actionBact/fung/tuberculo/vuru and sporicidalEffective for 2 daysPenetrate dentinal tubules
25
Explain how Iodine Potassium Iodide works?
Attacks proteins, nucleotides and FAs leading to cell deathLow tox, but patient allergic to iodine
26
What is the formulation of Iodine Potassium Iodide?
Irrigating sol 2% iodine in 4% aqueous potassium iodide such as Videne (Adams)
27
What is the definition of H202?
Degrades to form water and oxygen producing hydroxyl free radicalsEffective against bacteria, yeasts and viruses as it attack the proteins and DNANot reduce bacterial load in RCS significantlyOxygen may penetrate into periarticular tissues causing surgical emphysema due to effervesceNot used in contemporary endo
28
What is the definition of hypochlorous acid?
Less toxic than NaOClSimilar to NaOClDissociates in sol into hypochlorite ions but the reduced level of discolouration compared to NaOCl means that any adverse effects are reducedNaOCl is more efficient as more Cl is available between the sol of same conc
29
What is the definition of electronically activated water?
Sol of hypochlorous acidGenerated via process of electrolysis from water and NaCl by an electrochemical deviceSafer than other solution as if less irritant if extruded into he periradicular tissuesCidalpH 5-7Sterilox
30
Name and give characteristics of non-active irrigants?
Sterile waterLA solutionLubricate files and carries sward in solNo disinfectant propNot recommended for sole irrigant
31
What is the definition of a co-irrigant?
More than 1 irrigant to enhance effectUsually consist of an acid or chelating agent + NaOCldissolve smear and assist in biofilm destruction + disinfect
32
What is the definition of Ozone?
Sterilising of water suppliesSterilising agentEffective and toxic dose very closeGas delivered down a handpiece
33
Explain how the Ozone device works?
Area sealed from the surroundings and residual gas is drawn back to the generator and neutralised using a Pl filterDeliver ozone down fine tip directly into canal for very short time
34
Name 2 device names for Ozone?
Healozone CurOzoneProzone W%H
35
What is the definition of bacterial photodynamic therapy?
Impossible to consistently disinfect enter RCS due to:- anatomy- disinfectants are ineffective against some organismsCombo of photo-sensitiser and specific wavelength is effect against all oral microorganisms
36
What is the definition of a photo-sensitiser?
Different wavelengths of activationTolonium Cl (relative of toluidine blue O)Conc between 13-80 ug/mlLower surface tension so can wet and penetrate into the dentinal tubulesNo problem with extracanal extrusion
37
What is the definition of a light source?
Laser diode or LEDRed light at 635nm +/- 2nmLight exists photo-sensitiser molsMinimal heatLight delivered via a tapered endodontic tip
38
Explain the mechanism of action for Bacterial PDT?
Photo-sensitiser is preferentially taken up by rapidly dividing cells such as microorganismsChemical must be in contact or in very close proximity to bacteriaTaken up by the liposomes on cell wallsWhen light energy is applied photo-sensitisermolecule becomes excited and free oxygen radicalsproduced Singlet oxygen species is a protoplasmic poisonwhich causes oxidative injury to bacterial cell wall Leads to death of microorganismPhoto-sensitiser returns to its unexcited state -causes no further effect when light switched offNo collateral damage seen to any surroundingtissuesResistant strains cannot be build upBoth light and photo-sensitiser are ineffectivewhen used separately.Also viricidal and fungicidal
39
Name 2 commercially available bacterial PDT?
CumdentPACTCumdente Dental Concepts Laser diodePAD Plus Denfotex Research LED
40
What is the aim of root canal preparation?
Remove as many microorganisms as possibleShape root canal to provide a uniform sized dead space to facilitate its subsequent obturation using stand sixed cones of plastic material and its adaptation to root canal walls to achieve a sealAvoid ledges, perforations zips and canal transportation
41
What are metal files used for?
Remove:- necrotic material from lumen of root canals- hard tissue from root canal walls- microorganisms that have penetrated dentinal tubuleFacilitate penetration of disinfecting agents so they reach the microorganisms in RCS
42
What force to files exert onto the RCS?
All files tend to straighten within a curved canal and exert a lateral force on the root canal wall
43
How can files be different?
ShapeTapersLengthCuttingNon-cutting tipsSade edgedColour/number coded
44
name 2 types of endodontic files?
Hand - composed of stainless steel or nickel-titaniumRotary - only nickel-titanium in a speed-reducing, torque controlled handpiece
45
Describe the anatomy of an endodontic file?
Both have cutting edges along the length of the fileHandle/attachment for drillSilicone stop
46
Explain how the cutting edge of the endodontic file cuts?
Cuts when its radial lands are in contact with canal wallLead angle determines cutting efficiencyRadial land areas required for conventional helically fluted files because they prevent the file from over-engagement in the canalLock of radial land areas reduces frictionFile may fracture if suddenly engagedRadial lands are important for files that have +ve rake anglesDesigned so that radial lands can't screw themselves into wallDebris directed towards coronal canal so not compacted apically
47
What is the definition of a rake angle?
Angle of action of the cutting blade us similar to a snow plough which is forces downwards towards surface of road
48
What is the definition of stainless steel files?
Alloy of iron, carbon and chromium + nickelForms an invisible passivation layer of chromium oxide on surface when exposed to airIf scratched, code later rapidly reforms preventing degradePrevents rusting in presence of water
49
How are stainless steel files manufactured?
Machine shaped directly from a stainless steel wireMachined into a blank of the desired shapeGreater # of twists greater the work hardening
50
What are the stainless steel file properties?
Do not bend easilyBend file prior to introductionBending instrument will further work harden the metal making it more brittle leading to fracture
51
What is the definition of a nickel-titanium files (NiTi)
500% more flexible than stainless steel and 3 times strongerCorrosion resistantHand and rotary instruments available
52
What are the 2 NiTi temperature dependent crystal structures?
Austenite - high temp or parent phase, cubic structureMartensite - low temp, monoclinic structure
53
What are the properties of NiTi alloy?
Superelasticity and shape memory effectOccur due to austenite to martensite transition induced by stress or temp (martensitic transformation)Under certain other condition other phase my be present (R-phase)
54
What is the definition and properties of austenite NiTi alloy?
Superelasticity due to austenite NiTiAustenite can be transformed to martensite by stress, termed stress-induced martensite transformationAllows complete recovery of deformation up to 8% strainStress-induced martensite state is not stable so retransformation back to austenite phase so spring back to original shapeLower elastic modulus than stains steelHigher torque values at fracture
55
What are the indications for Austenite NiTi files?
Shape straight or slightly curved canalsPathfinding instruments as compensation for the decreased torque resistance caused by small diameter filesProfile
56
What is the definition and properties of martensitic NiTi alloy?
Softer and more ductile than austeniticEasily deformed and exhibits shape memory effect when heatedPseudoplasticFatigue crack growth resistance is higher than stable austeniteHyflex
57
What are the properties of gold and blue heat-treated instruments?
Heat treat martensitic alloyBlue colour due to titanium oxide left after heatControlled memory effectEnhanced flexibility and cyclic fatigue resistance compared with conventional NiTi and M-WireGreater angle of rotation but lower torque at fracturePreferred un serve curved canalsPre-bendable to bypass ledges
58
Name 2 commercially available gold/blue heat treated instruments
Rotary system: ProTaper Gold (Dentsply Sirona)• Reciprocating motion: Reciproc Blue (VDW) &WaveOne Gold (Dentsply Sirona)
59
Explain the manufacturing process of NiTI endodontic instruments?
Conventional NiTi alloys are ground to make files opposed to twistedLead to defects n the surface so potentially causing decreased fracture resistance, cutting efficiency and corrosion resistanceElectropolishing sometime used to remove surface defects causing by grinding (improves above problems)
60
Explain how to choice between different endodontic files?
Rotary systems are much more efficient thanhand techniques• Hand files sometimes preferred to negotiate verycurved root canals although newer rotaries maybe used these days• Engine driven NiTi endodontic instruments result in significantly less canal transportationscompared to stainless steel hand instruments• Selection of material of which file is made and itsmethod of construction is critical in determiningperformance of instrument
61
What factors do stainless steel endodontic files depend on?
Composition of materialGeometry of fileWay in which it is loaded
62
What are the contraindication for use of a stainless steel endodontic file?
Anticlockwise twisting as this increases twisting resulting in brittle fractureNaOCl and EDTA reduce cutting ability so files should be rinsedLong prep times prolong immersion of instruments in these solutions in the canal and start process of degrad
63
Name 3 ways a file may break?
Sharp curve - cyclic fatigueOveruse - flexural fatigueIn rotation while instruments is prevented from moving - torsional fatigue
64
What is the definition of torsional stress? how to reduce it?
Evert cutting action in the canalTorque controller so that the rotation of file is stopped prior to receiving excessive torque
65
Explain the decontamination process for endodontic files?
Debris retained on file after use is called swarf• May contain neural tissue with prions• Proteins that cannot be destroyed by the usualmethods of surgical disinfection• Theoretically associated with new-variantCreutzfeldt–Jakob disease ( nvCJD )• Endodontic files should therefore be considered assingle use• Incidence of instrument separation is decreased• Autoclaving can decrease the cutting ability of somefiles and may result in metal fatigue
66
What are the 2 parts for inter-visist temporisation?
Canal medicamentsTemporary dressings
67
Explain why inter-visit temporisation is necessary?
Signs/symptomsFurther opportunity to disinfect the RCS by placing a medicament with antimicrobial propCases which require root formation to complete
68
Name 6 types of inter-visit canal medicaments?
Steroid/antibiotic comboNon-setting CaOHChlorhexidinePhenol or derivativesHalogensFormaldehyde
69
Indications for steroid/antibiotic paste?
Irreversible pulpitisIntracanal dressing between appointments
70
Name 1 commercially available steroid/antibiotic paste and its constituents?
OdontoPaste (Australian Dental Manufacturing)LedermixConstituents:- Clindamycin hydrochloride 5%- triamcinolone acetonide 1%- CaOH
71
Explain how the steroid/antibiotic paste works?
Acts topical only killing bacteria adjacent to vital tissueSteroid suppresses any inflamm responsePermits bacteria at a distance from surface of lesion to proliferate - leads to death of pulp
72
Why can endodontic steroid paste be useful for irreversible pulpitis?
When sufficient analgesia can't be gained to fully extirpate vital tissueOnly effective when it is in contact with vital tissue so rational is debatable
73
What are the pros of using steroid/antibiotic paste + non-setting CaOH?
LedermixSynergisticPlaced separately - too viscousPlace steroid/antibiotic paste on a paper point to carry it into canal followed by syringing non-setting CaOH
74
Give a description of non-setting CaOH?
Intracanal medicamentsActive chemical provided as a slurry in a water baseMethylcellulose basedFacilitate removal of the products from the canalRadiopaquepH is 12
75
Explain how non-setting CaOH works?
Bactericidal:- slow acting antimicrobial agent has therapeutic effect after being in situ at least a day- effective disinfection in most cases of infected necrotic cases seen in a weekNeutralises acidic endotoxinsInhibits osteoclastic activity due to high pH - useful in cases of inflamm root resorptionHydrolyses lipid component of bacterial LPS - renders bacteria inactive and reduces toxic effect from debrisDenatures proteins in RCSMay activate CA-dependent adenosine triphosphate reaction assoc with hard tissue formation stimulation periradicular healing
76
Name the 6 indications for non-setting CaOH?
Inter-visit intracanal medicament - disinfect canal systemControls exudation in persistent infectionPartial pulpotomy - create a calcific barrier to maintain vitality of toothApexogenesis - continue root formation in vital toothApexification - induces apical closure of non-vital immature teeth- dressing replaced every 6 weeks until hard tissue barrier formsResorption - inhibits activity of osteoclasts die to high pH so arresting inflamm process
77
Name the 3 contraindication for non-setting CaOH?
Cause calcification of canal if left in situ > 6 monthIncreases risk of root fracture due to denaturing the collagen
78
What is the mode of delivery of non-setting CaOH?
Past inside a tubeFine endodontic Needle (Navvi tip) attached to a Luer lock syringeDeliver paste into canalConsistency of paste must be as thick as possible to fill RCSCan be difficult to removeEffectively removed with citric acid or EDTA as alkaline CaOH reacts with acid
79
Name 1 commercial produce for non-setting CaOH?
UltraCal by Ultradent
80
What are the advantages of non-setting CaOH PLUS points over non-setting CaOH?
Greater release of CaOH and so more effectivePoints ready to use No mixingEasy to apply and removeNo smearing
81
Give a description of chlorhexidine?
Incorporated into gutta perchaActiv point (Roeko) is a 5% chlorhexidine diacetatePlaced in canal for 1-3 weeksConform to ISO specification for GP points for size and diameter which matches shape to that of root canalDrop of sterile water is sued to accelerate release of the chlorhexidineSame effects as a chlorhexidine irrigant
82
Give a description of phenol?
Effective antimicrobialsStrong antisepticsShort duration for effectProtoplasmic poison and works at an optimal conc of 1-2%
83
Give 3 examples of phenols?
Para-monochlorphenolThymolCresol
84
What did studies show about the use of phenols as disinfectants?
Not able to fully disinfect the RCS after 2 weeksDue to insufficient vapour released for effective antimicrobial action when the products placed on a cotton pellet in pulp chamber
85
Give 1 commercially available phenol product and its constituents?
Cresophene - SeptodontConstituents:- para-chlorophenol- dexamethasone with thymol and camphorHigh tox and carcinogenicObsolete in endodontic practice
86
Give a description of halogens?
AntimicrobialChlorine-containing products (chloramines)Iodine more popular such as iodine potassium iodideReleases vapours2% iodine prep quicker at reducing bacterial load than CaOHCan prevent E. faecalis growth within 1-2 hrs
87
Contraindications for iodine halogens?
Iodine hypersensitivity
88
Give a description of formaldehyde?
Caustinerf Forte - SeptodontToxicity of formaldehyde containing medicamentsNot justified
89
Give 7 key properties needed for a good coronal temporisation?
Coronal seal must be perfect - to prevent bacterial ingressFunctionAestheticsStrong to withstand occlusal loadsLow solubilityHigh wear resistanceLongevity
90
Name 5 materials used for inter-visit coronal temporisation?
GICZinc polycarboxylate cementReinforced zinc oxide eugenol cementZinc oxide containing puttiesSemi-permanent material - forming a core using a resin-mod glass ionomer cement, resin composite or amalgam
91
What to consider when placing a coronal termporisation material?
Need to consider final restorative material vizresin composite definitive restoration and useof a eugenol-containing cement
92
Name 2 types of coronal protection?
Tightly fitting copperOrthodontic band
93
What is the function of obturating material?
Prevents ingress of microorganisms by creating a seal at both coronal and apical ends, lateral canals and dentinal tubulesCompletely fills dead space removing all air which could expand or contract in a pressurised environment
94
Give a description of Gutta percha?
Consists of polyisoprene which comes from rubber treePolyisoprene has 2 isomeric forms:- cis = rubber- trans = GPTrans exists in 2 phases:- alpha phase is heated and used molten- beta are GP points or cones used at room temperatureMixed with other chemicals to enhance handling
95
Give a comparison between alpha and beta phase for trans polyisoprene?
Beta phase is formed when GP cooled quickly whereas alpha phase is formed if material is cooled slowlyAlpha form is denser and has better thermoplastic characteristics
96
Name the 4 constituents for GP and their functions?
Gutta perchaZinc Oxide - filler and antimicrobialResins - PlasticiserMetal sulphates - radiopacity
97
What are the physical properties of GP?
Highly biocompatibleMinimal tissue changesInertMinimal toxicityDimensionally stable and packableThermoplastic softening at 60-65C and melting at 100CStretchableAntibacterialRadiopaqueNo heat sterilisationOxidises on light exposure - degrades and becomes brittleLacks rigidityPoor adaptionShrinkage 2%
98
Explain how to sterilise GP?
Using NaOClDo not use acetone or alcohol to disinfect as it can be absorbed
99
What is the presentation of GP?
PointsConesSeveral different sizesDifferent tapers
100
What are the manufacturing tolerances for GP?
Subjected to ISO standardsCones are made to a tolerance of +/- 0.05mmDifferent products are composed of different proportions of chemicals creating variations in brittleness and stiffness
101
Explain the cold obturation technique for GP?
GP + endodontic seal to fill root canalCold lateral condensation - GSCone which corresponds in size to canal prep is coated with a root canal prep and introduced into root canalthen pushed laterally to create space so that next cone can be placedOther accessory cones coated with seaer are then introduced into canal one at a timeContinue until root canal is fully obturatedAdjust GP cone with scalpel bladeUse liquid GP - allows material to flow into irregularities of RCSGuttaFlow - Roeko (GP + addition cross-linking poly(dimethyl siloxane)30um particle size - 0.2% shrinkage
102
Name the 8 chemical constituents for GuttaFlow and their functions?
GP powder - obturating componentZInc oxide - filler and radiopacityZirconium dioxide - filler and radiopacitySilicone oil - binder + consistencyParaffin ol - binder + consistencyColloidal silver - inhibit reinfectionHexachloroplatinic acid - catalystColouring agent - colour
103
Explain the technique for warm GP?
Used at high temperatures as pelletsConjugation with gun150-230CNarrower gauge = lower temperatureOnce at temp molten material can be expressed out of needle of gun into canalSecure apical stop before suing molten GP - to prevent extrusionGood for obturating anatomical irregularities
104
What are some present techniques to cut GP?
Heat used to cut GPHeating over bunsen burner:- naked flame- burning other objects- tempers steel of instrument = damageSYstem B sears GP cleanlyWire inside probe heats up quicklyEasy and sade
105
Name 4 other obturation systems?
Real Seal 1 :- good for latex sensitivityThermafil:- softened GP flow into RC
106
What obturation product is indicated for patients sensitive to latex?
Real Seal 1Polyester with barium sulphate and silicate as radiopaque fillerCore is resin based with a Resilon outer coatingNo rubber or rubber-based materialsSoluble in chloroform and my be removed like GP
107
Give a description of ENdoREZ?
EndoREZ:- hydrophilic- dual cured resin obturation system based on UDMA and triethylene glycol dimethacrylate- polymerisation similar to resin composite- base and catalyst presentation- takes 20 mins can be sped up by accelerator- filler for radiopacity- master + accessory then light cure
108
Give a description of SmartSeal?
Smartseal:- hydrophobic polymer, - swell when water absorbed, - hoop system prevents excess swelling- flexible- points and sealer
109
What are the shortcoming of Silver points?
DO not fully obturate canalRely on RC sealerProne to corrosionCorrosion products high tox and can leachPermeate dentinal tubulesDifficult to remove as they tend to fractureRigid so can't adapt to walls
110
What is the definition of an endodontic sealer?
Paste coated onto endodontic point prior to its insertion into RCPaste/paste presentationUsed sparinglyPrvenets extracanal extrusion and decreases amount of sealer needed
111
What is the function of the endodontic sealer?
- Lubricate and facilitate full placement of master point +/-accessory cones• Fills voids between obturation points• Fills and seals lateral canals and passes through lateral canalsto root surface - seen radiographically as a ‘puff’ on side of root• Provide a disinfectant action if they contain an active component
112
Name and describe the 4 physical properties all endodontic sealers must display?
Flow - determines ability to effectively fill voidsbetween master cone and accessory cones and anyaccessory canals may be obturated.• Film thickness - should be minimal as sealer is by farmost likely material to degrade• Solubility - most sealers are soluble and are absorbedto some extent when exposed to tissue fluid, keep toa minimum• Radiodensity - should also be radiopaque
113
Name 6 types of endodontic sealers?
Zinc oxide eugenolCalcium hydroxideEpoxy resinGICPoly(dimethyl siloxanes)Tricalcium silicate cements
114
Give a description of Zinc oxide eugenol endodontic sealers?
Good results with cold techniquesSmall particle size to enhance flowWeakPorousSusceptible to decomposition in tissue fluidsLose volume as eugenol and zinc oxide are releasedResins/rosins added to decrease dissolutionCan act as sensitising agentZinc oxide antimicrobial and cytotoxicOther added chemicals:- germicides - antiseptic- Canada balsam - increases adhesion to dentine- corticosteroids - suppress inflamm- paraformaldehyde - antimicrobial
115
Name the chemical composition of Zinc oxide eugenol endodontic sealer?
Powder:Zinc oxide - fillerSilver - radiopacityOleoresins - viscosityStaybelite resin - binderDithymoliodide - antisepticBismuth subcarbonate/subiodide/trioxide/sulphate - radiopacitySodium borate - fillerThymol iodide - antisepticOils and waxesLiquid:- eugenol - cement former- canada balsam - viscosity- polymerised resin - reinforcing agent
116
Give a description of CaOH endodontic sealers?
Dissociates into an ionic form and may confer anantimicrobial effect and promote healingsealer must dissolve so leaving voidsin obturated material Sealer is more solublePoor cohesive strength
117
Name the chemical components for CaOH endodontic sealers?
Base:- CaOH - cement- Zinc Oxide - cementActivator:- Barium sulphate - radio- Titanium dioxide - filler/colour- Zinc stearate - binder
118
Give a description of epoxy resin endodontic sealers?
Good flow and sealing abilityHigh dimensional stabilityLow shrinkageSufficient working timeAdhesion to other materials and dentineAntibacterial propertiesLess porous and have greater hardnessTheir lower solubility and greater film thickness mayprove problematic if the material needs to be removedSoluble in chloroform which facilitates removalleast toxic of allendodontic sealersAllergy
119
Name the chemical components for Epoxy resin-based endodontic sealer?
Base:- silver powder - radio- bismuth oxide - radio- hexamethylenetetramine - hardener- titanium oxide - colour/fillerCatalyst:- bisphenoldiglycidyl ether - cement former
120
Explain the setting reaction for epoxy resin endodontic sealer?
Addition polymerisation reaction in which epoxidesand amine react to form long chains• No residual monomer remains with no by-products• Diamines present in cement provide highdimensional stability• Exothermic reaction• Poly(addition) reaction is temperature dependentand takes a substantial amount of time• Extended working time provided c4 hours
121
Give a description of GIC endodontic sealers?
Modified GICs• Low toxicity and induce little tissue irritation• Cytotoxic but this and any inflammatory responsesdecrease with time• Adhere to dentine but may be less good at sealing• Physical properties are better than zinc oxideeugenol with less coronal leakage• Leach fluoride which is taken up by dentine• More susceptible to dissolution if exposed to liquidsbefore maturation is complete
122
What are the chemical constituents for polydimethylsiloxane endodontic sealers?
Polydimethylsiloxane - Active componentSilicon oil - BinderParaffin base oil - BinderPlatinum salt- CatalystZirconium dioxide - Filler
123
Give a description of polymethylsiloxane endodontic sealer?
Insoluble so not resorbed - contraindicated indeciduous teeth• Dimensionally stable although there is an initialslight expansion on setting• Thin film thickness and good flow characteristicsallows material to flow into tubules and fins• Excellent biocompatibility• Cannot bond to dentine• No antibacterial properties
124
Give 1 commercially available polydimethylsiloxane endodontic sealer
RoekoSealDifficult to use with heatedtechniques as heat willdecrease working time
125
Give the properties of tricalcium silicate based endodontic sealer?
Bioactive• Stimulates bone regeneration (hydroxyapatite formation)• Promotes periradicular healing• Mineralisation of dentine• Biocompatible• Adhesion to dentine and GP• pH 11 & CaOH2release – antimicrobial• Dimensionally stable
126
Give 1 commercially available tricalcium silicate based endodontic sealer?
Use with GP points• Any obturationtechnique• BioRoot™ RCS(Septodont)• 1 spoon to 5 drops• Working time c15 mins• Setting time <4 hours• 45µm film thickness
127
Give a desctiption of formaldehyde containing obturating pastses?
Paraformaldehyde decomposes to give itsmonomer which is a water soluble proteindenaturing agent• Highly toxic, genotoxic, mutagenic andcarcinogenic• Cause severe inflammatory reactions andnecrosis with direct tissue contact• Cause permanent injury if applied to neuraltissue on extrusion outwith root canal spaceMay be transported to other parts of the body• Allergenic which causes contact dermatitis andhas also caused type 1 anaphylaxis• Leaching occurs for a long time and results inchronic inflammation• Prevents or delays healing and masksinflammatory process
128
Give 1 commercially available ZOE containing obturating pastes?
TubliSeal EWT - SybroEndo - ZOE
