EP1042943A1

EP1042943A1 - An irrigating medium for root canals

Info

Publication number: EP1042943A1
Application number: EP98965457A
Authority: EP
Inventors: Jacobus Theodorus Marais
Original assignee: Radical Waters IP Pty Ltd
Current assignee: Radical Waters IP Pty Ltd
Priority date: 1997-12-30
Filing date: 1998-12-24
Publication date: 2000-10-11
Also published as: JP2002500055A; AU2091899A; WO1999034652A1; EP1042943A4

Abstract

The use of antiseptics in root canal treatment so as to reduce the proliferation of bacteria and other microorganisms remaining i n the root canal after obturation.

Description

TITLE :

AN IRRIGATING MEDIUM FOR ROOT CANALS

INTRODUCTION AND BACKGROUND TO THE INVENTION

This invention relates to the use of antiseptics in root canal treatment so as

to reduce the proliferation of bacteria and other micro-organisms remaining

in the root canal after obturation.

Sodium hypochlorite is universally used as an antiseptic for root canal

irrigation, its principal functions in root canal treatment being microbicidai,

dissolving organic material and lubrication. However, a disadvantage of

sodium hypochlorite is that it is highly toxic to human tissues and cells in

concentrated form and potentially even fatal at the concentrations at which

it is at its most effective as an irrigating medium.

OBJECT OF THE INVENTION

It is accordingly an object of this invention to provide a novel, relatively

inexpensive and safe irrigating medium for root canals.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided the use of an

aqueous solution in the preparation of an irrigating medium for use in the

treatment of root canals, the aqueous solution being characterised in that

it is electro-chemicaily activated. The eiectro-chemically activated aqueous

solution may consist of an aqueous anion-containing and/or an aqueous cation-containing solution. The aqueous anion-containing solution and/or

aqueous cation-containing solution may be prepared by means of

electrolysis of an aqueous solution of a salt. The salt may be sodium

chloride. In particular, it may be non-iodated sodium chloride or potassium

chloride.

The anion-containing and the associated cation-containing solution may be

produced by an electro-chemical reactor or so-called electrolysis machine.

The anion-containing solution is referred to hereinafter for brevity as the

"anolyte solution" and the cation-containing solution is referred to

hereinafter for brevity as the "catholyte solution" . The anolyte solution and

the catholyte solution are preferably provided from an electro-chemical

reactor comprising a through-flow, electro-chemical cell having two co-axial

electrodes with a co-axial diaphragm between them so as to separate an

annular inter-electrode space into cathodic and anodic chambers.

The anolyte solution may be produced from a 10% aqueous NaCI solution,

electrolysed in the anodic chamber to produce activated or excited aqueous

solutions containing numerous free radicals, the anolyte solution having an

extremely high redox potential of up to about + 1 170 mV and a pH value

of about 2-7. These activated radical species may be labile and after about

96 hours the various radical species may disappear with no residues being produced.

The anolyte solution may include activated radical species such as CIO;

CIO^" ; HCIO; OH^" ; HO₂ ^' ; H₂O₂ ; 0₃ ; HO' ; S₂O₃ ^2" and CI₂O₆ ²\

The activated radical species have been found to have a synergistic anti¬

bacterial and/or anti-viral effect which is generally stronger than that of

chemical bactericides and has been found to be particularly effective against

viral organisms, spore and cyst forming bacteria including Gram positive and

Gram negative bacteria such as Enterococcus faecalis and Pseudomonas

aeruginosa.

The catholyte solution generally may have a pH of up to about 7-13 and a

redox potential of about -980 mV. The catholyte solution may include

activated radical species such as NaOH; KOH; Ca(OH)₂ ; Mg (OH)₂ ; HO^' ;

H₃O₂ - ; HO₂ ^" ; H₂O₂ ^" ; O₂ ^" ; OH^' ; O₂ ²\

It is believed that the activated oxidising radical species or free radicals

present in the anolyte solution act synergistically as a biocidal and virucidal

agent at a bacterial cellular level, while the activated reducing radical

species or free radicals present in the catholyte solution act synergistically

as a cleaning agent to dissolve organic material or biofilm protecting or covering micro-organisms and with the micro-organisms themselves.

It has been found that the efficacy of the use of the anolyte and/or

catholyte solution in the preparation of an irrigating medium for use in the

treatment of root canals depends upon the concentration of the anolyte

and/or the catholyte solutions, as measured by the oxidation-reduction

potential (ORP) or redox potential of the anolyte and/or the catholyte

solution, the exposure time, i.e. the contact time between the root canal

and the anolyte and/or the catholyte solutions and the temperature during

application. Anolyte has been found to be more effective at lower than at

higher temperatures.

According to a second aspect of the invention there is provided an irrigating

medium for irrigating root canals, the irrigating medium comprising an

aqueous solution being substantially as hereinbefore defined.

According to a third aspect of the invention there is provided a method for

irrigating root canals including the step of applying an clectro-chemically

activated aqueous solution to a root canal, substantially as hereinbefore

defined. DETAILED DESCRIPTION OF THE INVENTION

The method of irrigating root canals may include the steps of first applying

catholyte solution to the root canal, aimed at removing organic biofilm and

debris covering the inner walls of the root canal, and thereafter applying

anolyte solution to the root canal, aimed at disinfecting the inner walls of

the root canal and inner tubes in a tooth.

A preferred embodiment of the invention wili now be described by means

of two non-limiting examples.

. Example No. 1

20 single rooted teeth were collected from the Department of Oral

and Maxiilofacial Surgery of the Faculty of Dentistry of the University

of Pretoria, South Africa, immediately after extraction from patients'

mouths.

1 .1 Testwork

The extracted teeth were rinsed under running potable water

and stored in specimen bottles filled with distilled water for 24

hours. The pulp chambers of the teeth were then accessed by

the use of fissure burs in turbine handpieces and round burs in

contra-angle handpieces. A number 1 5 K-type root canal file was then introduced into

each root canal to establish the patency of the canal. The

exact length of each canal was determined by inserting a file

into the root canal until its tip just appeared through the apical

foramen. A siiicono rubber stop pre-fitted to the shaft of the

file was then adjusted to a coronal reference point, an intact

part of the tooth.

The file was then withdrawn and the length from file tip to

silicone stop was noted. An individual working length for each

tooth was calculated by subtracting 1 mm from the measured

length. The coronal thirds of all canals were pre-flared using

Gates Glidden burs in a contra-angle handpiece. At this stage,

the 20 teeth were randomly divided into two groups, namely

Group A and Group B, for irrigation with the conventional

sodium hypochlorite and the electro-chemically activated

solution (STEDS) in accordance with the present invention

respectively, each group consisting of 10 teeth. Group A (sodium hypochlorite) :

The root canals of Group A were prepared, using a series of K-

type files (size 1 5-60) manually and by irrigating with a 2,5%

solution of sodium hypochlorite, with an ultrasonic unit such

as a so-called Cavi-Endo (Dentsply) unit. Irrigation was

performed after the use of every size fiie for at least 10

seconds, using the same ultrasonic unit.

After the canal was prepared to a size 60, a final flush of

irrigation was carried out for a minimum of 30 seconds. A

minimum of 150 ml of 2,5% sodium hypochlorite was used in

the irrigating process of each tcoth.

Group B (Electro-chemically Activated Solution "STEDS")

STEDS was produced from a specially manufactured electro¬

chemical reactor, comprising a through flow, electro-chemical

cell having two co-axial cylindrical electrodes with a co-axial

diaphragm between them so as to separate an annular inter-

electrode space into cathodic and anodic chambers. The

STEDS produced included two separate solutions, namely

catholyte and anolyte solutions. The anolyte solution had a pH

of about 7.4 and a redox potential of about + 1 170 mV. The catholyte solution had a pH of about 9,5 and a redox potential

of about -980mV. These solutions were used to irrigate the

canals in Group B. Root canals were prepared using the same

size and types of files and the same manual techniques as in

Group A. Initially the catholyte solution was used to irrigate

the canals using the same ultrasonic unit as group B. After the

use of each size file, the canal was irrigated with anolyte

solution for at least 10 seconds.

After preparation to a size 60, a final flush of irrigation was

carried out for a maximum of 30 seconds using catholyte

solution. A minimum of 100 ml anolyte and 50 ml catholyte

solutions were used for each tooth.

Immediately after the above preparation and irrigation

procedures had been carried out, the teeth were again stored

in distilled water for 24 hours. Each tooth was then dissected

with the aid of a microtome. Specimens of the root canal

walls of the middle third of the roots, measuring roughly 2

mm by 2 mm, were prepared. The specimens were handled

with locking forceps throughout, eliminating contamination by

human hand. The specimens were placed into a dust-free incubator and allowed to air-dry for 10 days.

The air-dried specimens were mounted with conductive

adhesive onto metal bases and coated with gold and viewed in

a scanning electron microscope at various magnifications. The

amount of remaining debris on the root canal walls were

compared by noting the debris on the surfaces of twenty

representative samples of each group.

Results

The remaining debris in Group B was negligible. Group A

exhibited small but noticeable amounts of debris on the

surface of a number of specimens. In group B, it was noticed

that the so-called smear layer, clearly present in all samples of

Group A, had been removed in large areas.

Under the conditions of this study, STEDS compared

favourably as an irrigating material with sodium hypochlorite.

It removed a large degree of debris from the surfaces of the

prepared root canal walls. Example 2

2.1 Test ork

69 extracted teeth, had their root canals prepared in the same

manner as in Example 1. The teeth were then sterilised by

means of an autoclave and were placed under aseptic

conditions in 200 ml of BHI (brain-heart infusion) liquid culture

medium together with 1 .0 ml of an overnight broth culture of

each of the following organisms: E. faecalis, P.aeruginosa and

S.mutans. The teeth were kept in this broth for 7 days in an

incubator at 37° C.

At the end of the 7 day period, the teeth were removed with

a pair of sterile forceps from the broth. The bioload was

expected to be extremely high by this time and colony counts

were performed on the broth by doing a series of 10-fold

dilutions in triplicate. Aliquots of these dilutions (100 μl) were

spotted on 10% blood agar plates and spread with a sterile

metal spreader over the surface of the plates. After overnight

incubation at 37°C, these plates were counted and the number

of colony-forming units (cfus) estimated.

The teeth were washed together in a sterile bottle with 100 ml of normal saline, repeated 4 times, with fresh saline being

added after the contaminated saline was discarded. This

reduced the bioburden to a level where the technologist

carrying out the procedure was unlikely to develop an infection

from spray aerosols.

The teeth were placed with the access cavity side facing

upwards in sterile micro titre trays. Prior to treatment, all the

teeth were "irrigated" down the access cavity with 50 ml

sterile water using a syringe, for 5 minutes, this being similar

to a manual irrigation procedure in the dental surgery. The

teeth were then held upside-down for a few seconds to allow

most of the water to drain off. The teeth were then divided

into different groups for the various treatments.

Three groups of 20 teeth each were created, with three

individual teeth serving as the catholyte control group and the

six other teeth for whole tooth studies.

In Group A (negative control) all the teeth's root canals were

irrigated with saline for 5 minutes, using a fine-needle

tuberculin syringe. 30 μi saline was then aspirated from the root canals, serially diluted and spread plated onto 10% blood

agar plates and incubated at 37°C for 24 hours.

In Group B, 20 teeth were similarly treated with sodium

hypoclorite for 5 and 10 minutes respectively. After 5 minutes

and again after 10 minutes, the canals were filled with saline,

and 30μl saline were then aspirated, diluted, plated, and

incubated.

In Group C all teeth were first treated with catholyte for 5

minutes. After this time, the catholyte was rinsed off with

anolyte solution. The teeth were then treated with anolyte for

5 and 10 minutes respectively. At the end of these periods,

the same culturing procedure, using saline, was used to take

samples from the root canals.

Whole tooth studies were conducted on six of the teeth, as

mentioned above. Two of the teeth were stored in sodium

hypochlorite and cultures taken after 5 and 10 minutes. The

two remaining teeth were stored in the catholyte, rinsed with

- and stored in the anolyte. Cultures were taken after 5 and

10 minutes storage time. Results

2.2.1 Baseline counts

The broth was shown to contain 4.4 x 10¹⁰ cfus after 7 days'

incubation with frequent additions of fresh culture medium.

The average numbers of organisms present in the root canals

after treatment with saline only was 1 .4 x 10⁶ cfus. The

reason for this high count was that most of the organisms

remained behind as a biofilm. An unexpected finding was that

following catholyte treatment (with no anolyte), the count

went up to 2 x 10' cfus. This is presumably because

catholyte is known to act in a similar way to a detergent,

lifting the biofilm from the surface.

2.2.2 Test Products

AVERAGE NUMBER OF COLONY-FORMING UNITS IN ROOT CANALS

OBTAINED AFTER EXPOSURE

2.2.3 Whole Tooth Counts

When the teeth were treated with sodium hypochlorite only for 5

minutes, the average count was 4 x 10² cfus. The counts dropped

to zero when left for 10 minutes.

Using anolyte only (no catholyte pre-treatment) the average count

was 1.2 x 10⁵. However, when the teeth were exposed to catholyte,

irrigated and then treated with anolyte for 10 minutes, the count

dropped to zero.

This in vitro study shows that anolyte is highly effective in eradicating both piaπktonic and sessile organisms adherent to the

tooth surface.

It is important that catholyte be applied first and then the catholyte

and the loosened biofilm MUST be rinsed off for really effective

results with the anolyte treatment.

It will be appreciated that many variations in detail are possible without

departing from the scope and/or spirit of the invention as defined in the

claims hereinafter.

Claims

1 . Use of an aqueous solution in the preparation of an irrigating medium

for use in the treatment of root canals, the aqueous solution being

characterised in that it is electro-chemically activated.

2. The use as claimed in claim 1 , wherein the electro-chemicclly

activated aqueous solution includes an aqueous anion-containing and

an aqueous cation-containing solution.

3. The use as claimed in claim 2, wherein the aqueous anion-containing

solution and the aqueous cation-containing solution are prepared by

means of electrolysis of an aqueous solution of a salt.

4. The use as claimed in any one of the preceding claims wherein the

anion-containing and the cation-containing solution are produced by

an electro-chemical reactor comprising a through-flow, electro┬¼

chemical cell having two co-axial electrodes with a co-axial

diaphragm between them so as to separate an annular inter-electrode

space into cathodic and anodic chambers.

5. The use as claimed in any one of the preceding claims wherein the

i 6 anion-containing solution is produced from a 10% aqueous NaCI

solution, electrolysed to produce activated or excited radical cation

and radical anion species, the anion-containing solution having an

extremely high redox potential of up to about + 1 170 mV.

6. The use as claimed in claim 5 wherein the anion-containing solution

has a pH of about 2-7 and a redox potential of about -h 1 170 mV.

7. The use as claimed in claim 5 wherein the cation-containing solution

has a pH of up to about 7-13 and a redox potential of about -980

mV.

8. An irrigating medium for irrigating root canals, the irrigating medium

comprising an electro-chemically activated, aqueous saline solution.

9. A method for irrigating root canals including the step of applying an

electro-chemically activated, aqueous saline solution to a root canal

for irrigation purposes.

0. The method as claimed in claim 9 including the steps of first applying

cation-contai╧Çing solution to the root canal, aimed at removing

organic fiim and debris covering the inner walls of the root canal, and

thereafter applying an anion-containing solution to the root canal,

aimed at disinfecting the inner walls of the root canal and dentinal

tubules.