CHELATING AGENTS IN ENDODONTICSKANWALPREET DHALIWAL

CONTENTSINTRODUCTIONHISTORYUSESPREPARATIONS AVAILABLEMECHANISM OF ACTIONEFFECT OF ROOT STRUCTUREROLE OF IRRIGANTSROLE OF SMEAR LAYER

WORKING TIMEBIOCOMPATABILITYANTIBACTERIAL ACTIVITYEFFECT ON OBTURATIONBLEACHING EFFECTCONCLUSIONRECOMMENDATIONS

INTRODUCTIONCHELATE----- CHELE----- CRAB CLAW

Stable complexes metal ions with organic substances --- ring shaped bonds.

Stability of bond:

Chelator: more than one free pair of electrons

Central metal ion: less electrons (Grossman et al 1988)

Action of ChelatorAbility to bind and inactivate metal ions.

Used for excretion of dangerous ions in metal poisoning or copper metabolism disturbances.( Zeeck et al 1992)

HISTORY1951 first reports of demineralizing effects of EDTA on dental hard tissues Hahn & Reygadas.Phenolorphonic acids, reverse aqua regia, caustic elements used.1957 NYGAARD OSTBY endodontics 15% EDTA(pH 7.3)1963- EDTAC (0.84g cetavlon- detergent)-Goldberg.1969- RC- PREP- Stewart et al paste type chelator.

USESAdjuncts endodontic therapyRemoval of smear layerIncreased importance- rotary NiTi instruments.

Chelator preparations:Liquid typePaste type

Liquid type:Calcinase:Lege artis, Dettenhausen, Germany.17% sodium EDTASodium hydroxide stabilizerPurified water.

REDTA:Roth international, USA17% EDTA0.84g cetyl tri methyl ammonium bromide cetrimide9.25 ml- 5 M NaOH100ml distilled water

EDTAC & DTPAC:

EDTA 15%, diethyl triamine penta acetic acid

pH 8

0.75g cetyl tri methyl ammonium bromide 100ml

EDTA- TFormula & Acao farmacia, Brazil17% EDTA Sodium lauryl ether sulphate ( Tergentol)

EGTASigma, USA

Ethylene glycol bis- N,N,N,Ntetra acetic acid (beta amino ethyl ether)Binds to calcium ions more specifically than EDTA.

CDTA:1% solution cyclohexane 1,2- diaminetetraacetic acid

Experimental solution

Largal UltraSeptodont, France

15%EDTA as disodium salt0.75% CetrimideSodium hydroxidepH 7.4

SalvizolRavens Germany

5% aminoquinaldinum diacetatePropylene glycolpH 6.6

DecalVeikko Auer, Finland5.3% oxyl-acetate4.6%ammonium oxyl acetate0.06% cetyltrimethyl ammonium bromidepH 3.4Acid component and chelator

Tubulicid plus Dental therapeutics, Sweden

1.5g amphoteric-2(38%)0.5g benzalkonichloride3g disodium EDTA dihydratePhosphate buffer solution100g distilled water50% citric acid

Hyapaque5%NaOCl17% EDTAHyapaque:- high contrast injectable dye diatrizoate meglumine sodium iodine water soluble pH 6.7 7.7Ruddles solution

Paste typeCalcinase slideLege artis, Germany

15% sodium EDTA58 64% waterNo peroxides, preservatives- self preservingpH 8-9

RC Prep:Premier dental, USA

10% urea peroxide15% EDTAGlycolAqueous ointment base

Glyde fileDetrey Dentsply, Germany

15% EDTA10% urea peroxide

Filecare EDTA:VDW antaeous, Germany15% EDTA , 10% urea peroxide

File EZEUltra dent, USA19% EDTA

Chelator preparations:Liquid typeCalcinaseREDTAEDTAC&DTPACEGTACDTALargal ultraSalvizolDecalTublicid plusPaste typeCalcinase slideRC PrepGlyde fileFile care EDTAFile EZE.

Advantages of pastes:Can be easily mixed with water, easy to rinse out of canal.Thixotrophic- firm at room temp.Easily adheres to instrument and root canal walls.

Mechanism of actionPRINCIPLE:Concept of constant solubility product of dentin by EDTA and its sodium salt.( Nygaard & Ostby) Tooth dentin + EDTA precipitate saturated salt solution( constant conc.) solids ions

Phosphate + calcium (soluble in water, part of dentin)

Calcium, phosphate + 2 Na EDTA calcium ions

Further dissolution of calcium ions continues.

Action is self limiting:When all the ions are bound , demin stops.EDTAH-3 + Ca 2+ EDTACa 2- +HEDTAH 3- + H EDTAH22-Deprotonation of EDTA occurs as the pH falls and reaction decreases.Demin continues till all the ions get bound.Nygaard & Ostby

Acc. To Paterson:Action is not self limiting:Continues till all the chelators form complexes with calcium at pH 4-5.

Effect of root structure demineralization in coronal and middle third. demineralization in apical portion.

Apical portion: increased sclerosis(schroeder 1992)less NCP/ non collagenous matrix proteinsEDTA removes ca bound with NCP and NCP as suchEffect is amount of solution dependantApical portion- narrow canal- less sol less demin.

Role of irrigants:

NaOCl accelerates erosion of dentinal tubules( Niu 2002)Synergistic effect

As smear layer is removed, increased dentin permeation occurs leading to crystal formation in the d.t. which decreases the permeability. NaOCl removes these crystals.(mjor2002)Increased permeability- decreased microleakage- better obturation.

EDTA+ NaOCl+ ultrasonic (Goldberg, Yamada, Abbott, Baumgartner)Cleaning actionAntimicrobial actionEDTA: removes smear layer(Mc Comb& Smith)Causes dentinal tubule erosion(Torabinejad)Dissolution of peritubular dentin(Goldberg)

Na0Cl no effect on EDTAEDTA- decreases the effect of NaOCl( Cl decreases by 0.50 to 0.06%)(Graweher 2003)Therefore use the two solutions separately

Ultrasonic:(Abbott 1991)Decreases the effect of EDTA:Decrease the working timeHinder the reaction.Therefore use ultrasonics with NaOCl

Smear layerGround substance, pulpal remnants, odontoblast processes, irrigants, bacteria(infected teeth)

1.Removal of SL(Brannstrom, Bystrom, Sundvist:Increased bacterial multiplicationDecreased permeation of intracanal medicamentsDecreased adaptation of GP.2. Do not remove smear layer(diamond and carrel)Prevents bacterial invasion of dentinal tubulesNot a site of bacterial colonization

Working time of EDTA15min (Goldberg & Spielberg)14 hrs (MCCOMB ands Smith)No diff 15min/14hrs(Nicholsan)1-5 min (Yamada)1 min exposure removes smear layer10 min exposure increases peritubular and intertubular erosion, undesirable( Calt Serper)Therefore, no definite time recommended for optimal working.

Biocompatibility of chelating agentsNygaard& Ostby: 15% EDTA no periapical damage.Paterson 1963 no effect of EDTA but EDTAC causes increased periapical damage.Lindeman 1985 EDTA not capable of collagen destruction.Cao et al 1992 if dentin intact, no affect on pulp ( used for dentin conditioning)Koilaouzi et al 1999 severe irritation and cytotoxic.

Segura et al 1996 :Irreversible decalcification of periapical bone.Inhibits binding of vasoactive intestinal peptides)VIP) to macrophages thus altering their action:Increased inflammatory initiationDecreased phagocytic activityIncreases plasma extravasationIncreased mediator actionDecreased action potential of nervesEXTRUSION OF EDTA INTO PERIAPICAL TISSUES SHOULD BE AVOIDED.

ANTIBACTERIAL ACTIVITY OF EDTACauses chelation of cations from the outer membrane of bacterial cellsActivity present only till it has not formed bonds with other metal ionsZone of bacterial inhibition produced.Increased efficacy with NaOCl( Bystrom & Sundqvist)Smear layer removal a must.

Antibacterial activity of various products:REDTA:Salvizol- fungicidal, broad spectrum antimicrobial(Narwrath 1960)Decreases toxicityInhibits anaerobic growth.

RC Prep:Increased efficacy against gram negative bacteriaUrea peroxide: oxidizing antibacterial agent., retains activity in presence of blood.Decreased growth of porphyromonas gingivalis, strepto. Sobrinus, prevotella nigrescens.

94.4% decrease in bacterial growth without intracanal medicament. (Steinberg 1999)Antibacterial concentration:0.25%EDTA0.5% urea peroxide50% glycol

Effect of EDTA on quality of obturationIncreased accessory canal obturated(Villegas 2002)Best results: Obtura II, system BSealers:Best adhesive seal: sealer 26 (Dentsply)Ca(OH)2 sealers: only slight increase in adhesion.

Negative effect( Morris et al 2001)Decreased bond strength of resin cements to root treated with EDTA and NaOCl:EDTA leaves a chelated dentin layer at the dentin sealer interfaceResidual EDTA ongoing demineralization- increased apical leakageEDTA and ZOE sealers: no significant diff in leakage.

Bleaching effects:Release of oxygen from urea peroxide causes effervescence but no bleaching effect noted ( Mattis & Attin et al 2003)

ConclusionsUse of chelators recommended during C&S.Reduce the extent of smear layer produced.Effectiveness depends on the time

Effect decreases from coronal towards apex.Antibacterial effect is low, do not replace liquid EDTA as irrigants in place of NaOCl.No evidence of bleaching noted.

Recommendations:Before adding EDTA, dissolve the vital/ necrotic tissue with NaOCl.Chelator acts as a lubricant, reduces the incidence of file fracture, no definite clinical evidence.A final rinse of EDTA helps remove smear layer, increases adhesion of sealers.

Use for 1 to 5 min.Liquid EDTA can be introduced with pipette or cotton to identify entrance to calcified canals.Apical extrusion is to be avoided.Dont use to open a ledge or block in the canal( perforations)Do not use glass syringe to deliver EDTA.