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ePaper created 2016-05-18, 11:28:18 | version 1.38.0
| review canal disinfection 16 roots 2 2016 New Technologies— to improve root canal disinfection Authors: Drs Gianluca Plotino, Nicola M. Grande & Prof. Gianluca Gambarini, Italy Introduction The major causative role of micro-organisms in thepathogenesisofpulpandperiapicaldiseaseshas clearly been demonstrated.1 The main aim of end- odontic therapy is to disinfect the entire root canal system,whichrequirestheeliminationofmicro-or- ganismsandmicrobialcomponentsandthepreven- tion of its reinfection during and after treatment. This goal is pursued through chemomechanical de- bridement, for which mechanical systems are used with irrigating solutions. Standard endodontic irrigation protocol Sodium hypochlorite Sodium hypochlorite (NaOCl) is the main end- odontic irrigant used, owing to its antibacterial properties and its ability to dissolve organic tissue.2 NaOCl is used during the instrumentation phase to increase its time of action within the canal as much aspossiblewithoutitbeingchemicallyalteredbythe presence of other substances.3 The effectiveness of this irrigant has been shown to depend on its con- centration, temperature, pH solution and storage conditions.3 Heated solutions (45–60 °C) and higher concentrations(5–6 %)havegreatertissue-dissolv- ingproperties.2 However,thegreatertheconcentra- tion, the more severe the potential reaction if some of the irrigant is inadvertently forced into the peri- apical tissue.4 In order to reduce this risk, the use of speciallydesignedendodonticneedlesandaninjec- tion technique without pressure is recommended.5 EDTA The main disadvantage of NaOCl is its inability to remove the smear layer. For this reason, combina- tionofNaOClwithEDTA(ethylenediaminetetraacetic) is recommended.2 EDTA has the ability to decom- pose the inorganic component of intracanal debris andisgenerallyusedinapercentageequalto17 %. EDTA appears to reduce the antibacterial and sol- vent activity of NaOCl; thus, these two liquids shouldnotbepresentinthecanalatsametime.6 For this reason, during mechanical preparation, abun- dantandfrequentrinsingwithNaOClisperformed, while the EDTA is used for 2 min at the end of the preparation phase to remove the inorganic debris and the smear layer from the canal walls com- pletely. Ultrasonic activation of NaOCl Theuseofultrasoundduringandattheendofthe rootcanalpreparationphaseisanindispensablestep in improving endodontic disinfection. The range of frequencies used in the ultrasonic unit is between 25 and 40 kHz.7 The effectiveness of ultrasound in irri- gationisdeterminedbyitsabilitytoproducecavita- tionandacousticstreaming.Cavitationisminimized and limited to the tip of the instrument used, while theeffectofacousticstreamingismoresignificant.7 Ultrasound creates bubbles of positive and neg- ative pressure in the molecules of the liquid with which it comes into contact. The bubbles become unstable,collapseandcauseanimplosionsimilarto a vacuum decompression. Exploding and implod- ing they release impact energy that is responsible for the detergent effect. It has been demonstrated that ultrasonic activation of NaOCl dramatically enhances its effectiveness in cleaning the root ca- nalspace,asultrasonicactivationgreatlyincreases the flow of liquid and improves both the solvent and antibacterial capacities and the removal effect oforganicandinorganicdebrisfromtheroot canal walls.7 22016