Root Canal Irrigants and Disinfectants

Question 1

Disinfectant of choice

Answer 1

Sodium hyperchlorite

and also 2% chlorohexidine

Question 2

Dentin surface modifier

Answer 2

17% EDTA

Ethylene Diamine Tetra- acetic acid

Question 3

Inter-appointment medicaments

Answer 3

1. calcium hydroxide
2. double/triple antibiotics
   - ciprofloxacin
   - metronidazole
   - minocycline

Question 4

Five main characteristics of an ideal irrigant

Answer 4

1. remove pathogens and debris
   - kill bacteria of all forms
   - fluid flush (hydodynamics)
   - dissolve organic and inorganic compounds
2. Facilitates instrumentation
   - accessibility
   - lubrication
3. low cytotoxicity
4. substantivity
5. minimal effects on the physical properties of dentin

Question 5

two main challenges in disinfection

Answer 5

1. complex anatomy
   - instrumentation limits
   - confined structure
2. bacterial characteristics
   - planktonic vs biofilm
   - dentinal tubule infection

Question 6

pH of the irrigant of choice and concentration?

Answer 6

pH of 11

ph of 9 is when reaction starts occuring

concentration is .5-5.25

Question 7

difference in lower and higher concentrations with sodium hyopchlorite use

Answer 7

lower concentrations of .5-1% is a sufficient to be bactericidal and dissolve necrotic tissue and does minimal effect to vital tissue

higher concentration 1- 5.25% is more efficient in action but significantly cytotoxic

these are the lower and higher ends

Question 8

what is full strength concentration of NaOCl?

Answer 8

5.25%

Question 9

NaOCl component in fatty acid saponification

Answer 9

Basic - sodium hydroxide + fatty acid –>

gives soap and glycerol
- which will also reduce the surface tension

Question 10

NaOCl component in amino acid neutralization reaction

Answer 10

the NaOH - sodium hydroxide can combine with the amino acids and neutralize –> you get salt and water

Question 11

NaOCl component in amino acid chloromination reaction

Answer 11

the acidic component (HOCl hypochlorous acid) combines with amino acids and gives –> chloramine and water

Question 12

three main mechanisms of NaOCl

Answer 12

1. fatty acid saponification reaction
2. amino acid neutralization reaction
3. amino acid chloramination reaction

Question 13

what mechanisms do you see the organic dissolution action observed?

Answer 13

in the saponification reaction when sodium hypochlorite degrades lipids and fatty acids resulting in the foramtion of soap and glycerol

Question 14

what to bacterial essential enzymatic sites account for?

Answer 14

they are related to the antimicrobial activity and promote irreversible inactivation by hydroxyl ions and the chlotamination reactoin

Question 15

importance of chlorine in the action of NaOCl?

Answer 15

it is strong oxidant that presents antimicrobial action inhibiting bacterial enzymes leading to an irreversible oxidation of SH groups (sulphydryl group) of essential bacterial enzymes

Question 16

is sodium hyperchlorite a selective agent?

Answer 16

no

- so need to be careful about concentration usages

Question 17

what is a major complication of sodium hyperchlorite?

Answer 17

immediate pain

edema

profuse interstitial bleeding with hemorrhage of the slon and mucosa (ecchymosis)

Question 18

sodium hypochlorite complication management

Answer 18

1. reassure patients
2. long lasting anesthetics for pain
3. clinical assessment
4. establish drainage
5. severe may eed surgical decompression to remove necrotic debris and facilitate drainage
6. cold compression initially for 1-2 days then warm compression

Question 19

for complication management do you need to perscribe antihistamine? corticosteroids?

Answer 19

antihistamine – only if sinus tract involved

corticosteroids is controversal

may need prophylatic antibiotics for prevention of secondary infection

Question 20

other irrigant of choice if contraindication with sodium hypochlorite? its major downfall?

Answer 20

2% chlorhexidine

it CANNOT DISSOLVE ORGANIC MATERIAL – so it can kill bacteria but will not dissolve its fragments and some of these may be left behind even after irrigation

Question 21

2% chlorhexidine complication

Answer 21

Carcinogenic and heamatotoxic PCA (ParaChloAniline) occurs when mixing ch lorohexidine with NaOCl or heating it

** the precipitation blocks dentinal tububles and compromises the seal of root canal seal

so need to replace NaOCl completely prior to chlorohexidine

Question 22

mechanism of 2% chlorhexidine? activity depends on?

Answer 22

cationic component attaches to negatively charged cell membrane areas and causes lysis

activity will depend on the pH and also the presence of organic matter as its activity is greatly REDUCED in the presence of organic material

Question 23

how to avoid PCA if need to use 2% chlorhexidine

Answer 23

1. replace NaOCl completely prior to chlorohexidine
2. avoid extensive ultrasonic agitation
3. avoid heating

Question 24

dentin surface modifier we use, characteristics, and mode of action

Answer 24

EDTA at 17 % which will remove the smear layer and demineralize dentin suface by 50 um
- CALCIUM CHELATING AGENT USED IN SMEAR LAYER REMOVAL

• has weak antimicrobial effect but less cytotoxic

Question 25

relationship between temperature and the NaOCl

Answer 25

at 45 degrees celcius - pulp was dissolved as effectively at this temp when used a 1% concentration as opposed to 20 degrees at a 5.25 % concentration

• so we see 100 fold increase in killing efficacy between NaOCl solutions at 20 degrees vs 45 degrees

Question 26

when is calcium hydroxide used?

Answer 26

this is the MEDICAMENT OF CHOICE (where as sodium hypochloride is the irrigation of choice)

most commonly used intra-canal inter-appointment dressing

Question 27

mechanism of calcium hydroxide

Answer 27

antimicrobial because –works based upon the HIGH PH of 12.5