Marwa Mahmoud Bedier

Irrigants     
   and           Intracanal   
Medication

Infection control in human body

Successful elimination of opportunistic infections in most parts of the body requires only host defense mechanism and occasionally, systemic antibiotic or manipulative treatment.

Elimination of endodontic infections, however follows a different pathway due to special anatomical challenges.

The sequence of events are host defense, systemic antibiotics (in special indications), instrumentation and irrigation, intracanal medications, permanent root filling and coronal restoration.

Root canal disinfection by chemical means

Desired functions of irrigating solutions

Washing action (helps remove debris)

 Reduce instrument friction during preparation (lubricant)

 Facilitate dentin removal (lubricant)

 Dissolve inorganic tissue (dentin)

 Penetrate to canal periphery

 Dissolve organic matter (dentin collagen, pulp tissue, biofilm)

 Kill bacteria and yeasts (also in biofilm)

 Do not irritate or damage vital periapical tissue, no 

      caustic or cytotoxic effects

 Do not weaken tooth structure

 

A  sessile multicellular microbial community characterized by cells that are firmly attached to a surface enmeshed in self produced matrix of extracellular polymeric matrix.

 Characteristics of a Biofilm:

     1.Protection Against Environmental Stresses As:

2. Traps Nutrients And Metabolic Cooperatives For Bacterial Cell Beneficiary.

3. Compartmentalization, So that Different Species With Different Growth Requirements Can Survive.

 4. Allows the Horizontal Gene Pooling.

 5. Resist penetration of antimicrobial  agents

Biofilm can be removed or eliminated through the following methods:

mechanical removal by instruments (effective only in some areas of the root canal); dissolution by hypochlorite; and detachment by ultrasonic energy.

      Other chemical means,

      such as chlorhexidine, can kill biofilm bacteria if allowed long contact time. However, as they lack tissue-dissolving ability, the dead microbial biomass stays in the canal if not removed mechanically or dissolved by hypochlorite.

Any remaining organic matter, microbes, or vital or necrotic tissue jeopardizes the integrity of the seal of the root filling. Therefore the goal of the treatment is not only to kill the microbes in the root canal but also to remove them as completely as possible.

:Types 0f irrigants

It is the most popular irrigating solution.

It ionizes in water into Na+ and the hypochlorite ion, ocl-, establishing an equilibrium with hypochlorous acid (HOCl).

 At acidic and neutral pH, chlorine exists predominantly as HOCl, whereas at high pH of 9 and above, ocl predominates.

 Hypochlorous acid is responsible for the antibacterial activity; the OCl ion is less effective than the undissolved HOCl.

Hypochloric acid disrupts several vital functions of the microbial cell, resulting in cell death

Naocl is used in concentrations varying from 0.5 to 7%.

It is a potent antibacterial agent and effectively dissolve pulpal remnants and organic component of dentin

It is used both unbuffered solution at pH 11 and buffered with bicarbonate pH 9 as 0.5 %  (Dakin’s solution) or 1% (Spangberge and Haapasalo 2002)

Zehnder et al ., 2002 reported that buffering had little effect on tissue dissolution

Radcliffe et al., 2004 found that 5.25% was efficient in killing Enterococci in 2 min of direct contact, 10 sec  of 0.5% for deactivation of Actinomyces organisms and 1 min of 6% for candida

Vianna et al., 2004 reported that gram-negative anaerobic rods; Porphyromonas gingivalis, Porphyromonas endodontlis and Provetlla intermidia, often isolated from apical peridontitis  were killed within 15 sec with o.5- 5% conc of Naocl.

Mohamadi et al., 2011 studied the antibacterial activity of new modified Naocl- based endodontic irritant

     (Hypoclean) and it showed no bacterial growth after treatment. 

Dentin Erosion

One of the goals of endodontic treatment is to protect the tooth structure so that the physical procedures and chemical treatments do not cause weakening of the dentin/root.

 

A few studies have shown that long-term exposure to high concentrations of hypochlorite can lead to considerable reduction in the flexural strength and elastic modus of dentin. Mareending et al.,2007.

 Niu W et al., 2002 found that short-term irrigation with hypochlorite after EDTA or CA at the end of chemomechanical preparation causes strong erosion of the canal-wall surface dentin.

Cleaning of Uninstrumented Parts of the Root-canal System

Irrigation is most feasible in the instrumented areas because the irrigation needle can follow the smooth path created by the instruments. Cleaning and removing of necrotic tissue, debris, and biofilms from untouched areas rely completely on chemical means and sufficient use of sodium hypochlorite is the key factor in obtaining the desired results in these areas

Combination Products

Neutral EDTA17% , have optimal working time 15 minutes( self-limiting decalcification).

It  showed higher degree of decalcification of dentin surfaces than RC-prep(gel) which composed of EDTA+urea peroxide

Detergents(centrimide) have been added to some EDTA preparations (eg, SmearClear) to lower their surface tension and to improve their penetration in the root canal.

Citric acid

     Organic acid demineralize intertubular dentin make tubular opening larger than that of EDTA

Smear layer management

Smear layer composed of dentin shaving, cell debris and pulp remnants.

It is removed by the action of chelating agent and Naocl.

Controversery:

It will plug the dentinal tubules prevent the egress of bacteria

Its presence will affect the disinfection and increase microleakage

Zand et al.,2010 compared the effect of Naocl gel and solution in the removal of the smear layer from root canal walls and it was concluded that the use of the gel can be as effective as the solution along with EDTA in removal of the smear layer.

it is a broad spectrum antimicrobial agent against gram negative and gram positive

It has a cationic molecular component that attach to negatively charged cell membrane causing cell lysis (Gomes et al.,2007)

It permeates the cell wall or outer membrane (gram- negative cell) and attack inner membrane of the yeast plasma membrane (Haapasalo 2002)

2%  is used based on its substantively and long lasting antimicrobial effect which arise from its binding to hydroxyapatite(adsorb)

 Ercan et al 2006. reported that 2%gell CHX more effective than CaoH+2”%CHX or CaoH alone against E. fecalis and C. albicana after 7 15 30 days

Recently, a few studies of the antibacterial activity of a chlorhexidine product with surface-active agents (CHX-Plus) compared with regular CHX, both with 2% concentrations. The studies have shown superior killing of biofilm bacteria by the combination product.

CHX has no tissue-dissolving activity and there have been efforts to combine CHX with hypochlorite solutions.

However, CHX and NaoCl are not soluble in each other; a brownish-orange precipitate is formed when they are mixed. the precipitate prevents the clinical use of the mixture.( toxic+ interfere with seal)

Atomic absorption spectrophotometry has indicated that the precipitate contains iron, which may be the reason for the orange development.

Presence of parachloroaniline, which may have mutagenic potential, has also been demonstrated in the precipitate.

Its effervescence action capable of removing loose debris and release of nascent oxygen works against anaerobic bacteria.

Heling and chandler 1998 found strong synergism between H202 and CHX in disinfection of infected dentin.

Iodine potassium iodide

Halogen: Iodine act as an oxidizing agent

It  penetrates rapidly into the microorganism and cause cell death by attacking proteins, nucleotide and other key molecules of the cell.

Combination of IKI with CHX may be able to kill CaoH resistance bacteria.

Siren et al., 2004 found that combination of CaoH with IkI or CHX in infected bovine dentin block were effective in dentin disinfection

      
 and Tetraclean MTAD

New development in Root canal disinfection

Heal ozone

    Tri atomic oxygen in gaseous or aqueous phase

    Antimicrobial activity

    Destruct cell wall.

Electrochemically activated water(superoxidized water/ oxidative potential)

     Saline electrolyzed to form hypochlorus acid and free chlorine (sterilox)

Aquantine endodontic cleanser

Garcia 2010, Aquatine EC appears to be the first hypochlorous acid approved to be a possible alternative to the use of NaoCl as an intracanal irrigant.

Natural fruit juice

chamomile hydroalcoholic extract and tea tree oil

 Endo-PTC cream acts as a lubricant and thus reduces friction between the instrument and the root canal wall.

This cream is a mixture of Tween 80 detergent, urea peroxide and carbowax as a lubricant.

yamazaki 2010, The use of 0.5% sodium hypochlorite in association with Endo-PTC cream was shown to be more effective in dentin cleaning from root canal walls than was 1% sodium hypochlorite

Jung et al 2008,  studied the disinfection of  immature teeth with triple antibiotic paste( ciprofloxacin- metronidazole-minocycline)  for revascularization of necrotic pulp .

    
   Physical means of      canal cleaning        and disinfection

Ultrasonically activated files have the potential to prepare and debride the canal.

Passive us irrigation (PUI): irrigation is not combined with simultaneous ultrasonic instrumentation.

Ultrasonic instrumentation(UI): is less effective in removing pulp tissue or smear layer, this may be due to reduction of acoustic streaming and cavitation.

Sonically activated irrigation:

EndoActivator

Vibringe

Negative and postive pressure irrigation:

RinsEndo

The system is based on a pressure-suction mechanism

with approximately 100 cycles per minute.

Desai et al 2009, reported that the risk of over irrigation was comparable with manual and RinsEndo irrigation, but higher than with EndoActivator or the EndoVac system.

Safety irrigator

Combined irrigation/evacuation system

Intracanal ultrviolet illuminator

Reduce E.Fecalis

Supplement after Naocl

Laser
Types of Laser Irradiation

 The carbon-dioxide laser,

 The Nd:YAG laser,( neodymium: yttrium aluminum garnet)

 The Argon laser,

 The Excimer laser,

 The Holmium:YAG laser,

 The Diode laser,

 more recently, The Erbium:YAG laser.

Bergman et al 2006,  defined  the role of laser as a disinfection by using Nd;YAG laser , they concluded that it is not an alternative but a supplement to the existing protocol of canal disinfection.

There are some limitation of intra-canal use such as the emittion of the laser energy from the optical fiber verticaly thus it is impossible to obtain uniform coverage of the canal in addition to the thermal damage to the periapical tissue.

Stabholz et al 2003,  used of new endodontic tip with ER;YAG laser to deliver the beam through a hollow tube that allow lateral emission of radiation

         PhotodynamicDisinfection or light activated therapy 

Pagonis et al 2010,studied the effects of poly(lacticco-glycolic acid) (PLGA) nanoparticles loaded with the photosensitizer methylene blue (MB) and light against Enterococcus faecalis.

The utilization of PLGA nanoparticles encapsulated with photoactive drugs may be a promising adjunct in antimicrobial endodontic treatment.

Non instrumentation  technique

Lussi et al 1993, introduced minimally invassive approach  for removal of the canal content and disinfection without using file.

 

Cleaning provided by oscillation of irrigation solution and reduced pressure

 

It differ from the recently introduced active irrigation system , as the still rely on mechanical shaping prior to irrigation while  in NIT canal is not enlarged.