Endodontics. Definition. Clinical and anatomical structure of teeth’ cavities and root canals of teeth. Endodontic instruments. Basic endodontic procedures: tooth cavity disclosure, amputation, extirpation of the pulp. Methods of medicament and instrumental treatment of root canals ("Step-Back", "Crown-down" techniques). Medications. Mistakes and complications in root canal treatment.

Lecturer: Levkiv MarianaDepartment of Therapeutic DentistryTSMU

Anatomy of tooth cavityParts of a pulp cavity. The pulp cavity of this mandibular second molar is made up of a coronal pulp chamber with pulp horns and two root (pulp) canals.

Anatomy of root canal

• Anatomy of apical part of the root

anatomical apical hole (apical foramen) - a place of transition the dentin into cement;

physiological hole (apical constriction) - the border between pulp and periodontium, placed 1 mm away from the X-ray hole;

X-ray hole.

Topographical and anatomical features of teeth cavities of different group of teeth.

Access preparations into pulp chambers showing orifices to canals. Ideally shaped openings provide access into the pulp chamber for endodontic treatment. Pulp canal orifices on the floor of each pulp chamber correspond with the number and location of pulp canals in each tooth.

Anterior - Anterior - TriangularTriangular

Canines - Canines - ovoidovoid

Premolar - RoundPremolar - Round

Molar - Molar - RhomboidRhomboid

Endodontic instrumentsAccording to ISO endodontic instruments are classified:

Hand instruments: files(K and H), barbed broaches,

spreader and plugger (vertical and lateral gutta

percha condensors ).

Rotary instruments: H-files and K-reamers for slow handpiece, lentulo spiral filler/rotary paste

filler.

Rotary instruments: Gates Glidden drills, Peeso reamer drills.

Pins: gutta percha pins, silver

• But its more convenient to use classification by Curson(1996) that is based on clinical usage of endodontic instruments.

Curson’s classification is as follows:

• - diagnostic instruments: root needles(Miller needles)

• - instruments for removing the soft teeth’ tissues: barbed broaches

• - instruments for passing, enlargement and shaping the root canals : (K-reamers, K- files, H-files)

The main endodontic instruments and their use

Barbed broaches•Functions and precautions

•• Finger instruments

•• Disposed of in the sharps’ container

••Used to remove the intact pulp

•• ‘Barbs’ on the broach snag the pulp

• to facilitate removal

•• They need to be used cautiously as

•they can bind and break in the canal

•Varieties•Available in different sizes and widths

• Gates Glidden drills• Function, features and precautions• •To enlarge the coronal third of the canal during endodontic treatment• • Small flame-shaped cutting instrument used in the conventional handpiece• • Different sizes – coded by rings or coloured bands on shank• •Are slightly flexible and will follow the canal shape but can perforate the canal if used too deeply• • Dispose of in sharps’ container• • Should be used only in the straight sections of • the canal

• Peeso reamer drillsFunction, features and precautions• •To remove gutta percha during post preparation• • Small flame-shaped cutting instrument used in the conventional handpiece• • Different sizes – coded by rings or coloured bands on shank• • Peeso reamers are not flexible or adaptable, if not used with care can perforate canal• • Dispose of in sharps’ container

• NiTi (Nickel titanium) rotary instruments• Function, features and directions for use

• • Used to clean and shape the canals

• • Used with endodontic handpiece and motor

• • NiTi is flexible and instruments follow the

• canal outline very well

• • Several varieties of systems with different

• sequences of instruments are used

• • Important to follow the manufacturer’s

• recommended speeds and instructions for use

• Varieties

• Different lengths: 21mm and 25mm

• Reamers Rarely used or indicated. Disadvantages of reamers include their inflexibility with size, which ⇑can result in a wider canal being cut apically. Have now been replaced by files.

• Files These are used either with a longitudinal

rasping or a rotary action (e.g. clockwise direction).

• The main types of file available are:

• K-type-file. Made by twisting a square metal blank. • K-flex file. Similar to K-file but made by twisting a

rhomboid shape blank alternating blades with acute and obtuse angles. More flexible than K-file but becomes blunt more quickly.

• Hedstroem file.

A. K - style file.

B. K - style reamer.

C. K - flex file.

Hedstroem file. Made by machining a continuous groove into a metal blank. More aggressive than K-file. Must never be used with a rotary action as liable to fracture.

• Endodontic K files. Also called: Root canal hand files• Function, features and precaution

• • Finger instrument

• • Colour coded by size. The 6 colours used most often are: size 15 (white); 20 (yellow); 25 (red); 30 (blue); 35 (green); 40 (black). Also available in size 6 (pink), 8 (grey) and 10 (purple)

• • Operator gradually increases the size of the

• file to smooth, shape and enlarge canal

• • The larger the number of the file, the larger

• the diameter of the working end

• • Disposed of in the sharps’ container

• Varieties

• • Different lengths: 21mm, 25mm and 30mm

• Lentulo spiral filler/rotary paste filler• Function and features• • Small flexible instrument used to place materials into

the canal• • Fits into the conventional handpiece• • Use with caution as it can be easily broken• • Different sizes available

Geometric symbols of endodontic instruments

Common terms and expressions used in endodontics

Pulpotomy (amputation)

Pulpectomy (extirpation)

Tooth cavity disclosure

The main purpose of root canal treatment is:

•removal of pulp;

•removal of infected dentine from the inner wall of the root canal;

•enlargement and shaping a root canal for its adequate filling.

The procedure of root canal treatment has such stages:

• - disclosure of the tooth cavity;

• - disclosure of the root canal orifices;

• - the root canal passing;

• - the root canal enlargement;

• - the root canal shaping.

Manipulations of root canal treatment (RCT) are carried out manually or with the help of rotary instruments by several treatment methods, the most widespread among them are:•apical-crown - envisage treatment from the apical hole to canal orifices with gradually increasing of instrument diameter( e.g. from №10 -№ 40)•crown-apical - envisage root canal treatment that starts from canal orifices to apical hole with a gradual decrease in instrument diameter(e.g. from №40 –№ 10)•hybrid method of treatment - have been developed out of the two methods.

Step-back technique The apical part of the root canal is prepared first and the canal is then flared from apex to crown. Blockage of canals may occur using this technique, and irrigation can be difficult.

Crown-down technique This (along with several others) prepares the coronal part of the canal before the apical part. This has advantages and is the preferred technique.

Balanced force technique This involves using blunt-tipped files with an anticlockwise rotation whilst applying an apically directed force. It requires practise to master but is particularly useful when preparing the apical part of severely curved canals.

(A) In the balanced force technique the file

is placed to working length and rotated

clockwise 90 degree with light pressure to

engage dentin.

(B) The file is then rotated

counterclockwise 120 degree while apical

pressure is maintained to cut and enlarge

the canal. Debris is removed with a final

clockwise rotation that loads the flutes

with loosened debris.

Anticurvature filing

• Advantages of orifice enlargement • • Effectively, the curvature in the coronal part of the root canal, ⇓

allowing straighter access for files to the apical region. It therefore reduces the likelihood of apical transportation (zipping).

• • It allows improved access for the flow of irrigant solution within the canal. • • It reduces the likelihood of apical extrusion of infected material as most of the canal debris is removed before apical instrumentation takes place. This is particularly important because the majority of bacteria in an infected root canal are located in the coronal region.

Drugs for chemical enlargement of root canals

Type of active ingredient The product, the manufacturing company

A solution of EDTA Largal ultra (“Septodont”) Edetat solution (“Pierre Roland”)Endofree (“Dencare”)

A solution of citric acid and propionic acid

Verifix (“Spad”)

Gels based on EDTA Canal+ (“Septodont”) HPU15 (“Spad”)RC-prep (“Premier”) Канал Глайд («Радуга-Р»)

Root canal treatment should include thorough mechanical debridement and medicatment treatment as well (antiseptic solutions), these two procedures should go together.Irrigants. Dilute sodium hypochlorite is generally considered to be the best irrigant as it is bacteriocidal and dissolves organic debris.

To be sufficiently enlarged;To have a conical shape (tapered);To have formed apical ledge;Do not contain a necrotic dentine;Do not have typical smell;To be clean and dry;Do not have a painful reaction to

percussion.

Prepared root canal for sealing, regardless of the method of instrumental treatment, must fulfill the following criteria as follows:

• Common errors in canal preparation

Elbow formation

Apical perforation

Strip perforation

Ledge formation

Apical transportation

Incomplete debridement

Lateral perforation

The stiff instrument tends to straighten within the curved root canal (1),

causing ledge formation (2), zipping (3) or perforation (4).