National medical university of LVIV department of therapeutic dentistry

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Control questions to|by| practical lesson


  1. What instruments are used for tooth cavity opening?

  2. What are the steps of the tooth cavity opening?

  3. How the roof of the pulp chamber is removed?

  4. What are the demands for the access cavity shape?

  5. Enumerate medications for pulp devitalization?

  6. Discribe the way of placement of pulp devitalization agents.

Situation tasks and test control
1. Localization of the access cavity on the occlusial surface concerning another surface:

a. А

b. В

c. С
2. Root canal orifice should be localized with help of:

A. condenser with a small working part

B. endodontic File No15

C. small ball round-shaped drill

D. endodontic probe
3. The most frequent clinical mistake in the lower incisor pulp chamber opening is:

A. lingual perforation

B. labial perforation

C. incisor is broken

D. lateral perforation
4. MB root of the 1-st upper molar:

A. it has only 1 canal

B. in the majority of cases it has 2 canals

C. has the second peep-hole, which is located towards the DB canal entrance

D. has the second peep-hole, which is situated towards the palatal canal entrance
5. What canal is the most lower in molar canal?

A. MB canal

B. ML canal

C. DB canal

D. DL canal
6. The sufficient access cavity opening:

A. allows to clean the cavity completely

B. makes the root canal instrumentation easier

C. the risk of a crown discoloration is the less possible

D. all are correct
7. What is the main purpose of access forming in the pulpectomy?

A. to widen the cavity including the pulp chamber

B. To make a coronal pulp amputation

C. To localize the orifice and provide straight access to the root canal

D. to widen the cavity including the pulp chamber and localize peep-holes
8. What is the aim of using the rubber dam?

A. Well visible working site

B. Aseptic

C. To protect a patient from endodontic tools and materials aspiration

D. everything is correct
9. Not aesthetic but endodontically correct access can be used for:

A. upper incisors

B. upper canines

C. lower incisors

D. lower premolars
10. The shapes of the central and lateral upper incisors access cavities most often are:

a. similar due to the likeness of their crowns and roots

b. triangle, and located in the incisor in the direction of the enamel tubercle paracervical on the palatal tooth surface

c. triangle and oval

d. execute with a fissure-staight drill
11. The 1-st upper molar mesio-buccal root can include:

a. usually 1 root canal

b. in most cases 2 root canals

c. has the second root canal peep-hole, which is located towards the MD peep-hole

d. has the second root canal peep-hole, which is located towards the P root canal peep-hole

12. The second upper molar morphologically differs from the second upper molar in:

a. divergent buccal roots

b. there are no parallel root canals

c. three roots, which are located with each other

D. the right-angled shape of the tooth cavity bottom

13. The narrow access preparation:

a. provides a good access to all root canals

b. makes impossible the root canal access with a straight line

c. allows a good pulp chamber cleaning

D. provides a good visualization of the possible additional root canals
14. In what cases the percentage of revealing the incisors with two apical openings is possible:

a. 1%

b. 10%

c. 20%

D. 30%
15. In what cases the percentage of revealing the МВ2 root canal in the first upper molar is possible:

a. 10%

b. 40%

c. more than 90 %

d. 60%
16. How can it be confirmed that the second canal is available?

a. To make an additional x-ray film in mesial or distal horizontal angle

b. To change the access forming

c. To make the the x-ray angle larger in vertical plain

d. to make an additional intra-oral x-ray of teeth and jaw in occlusion
17. Why is it recommended to estimate the working length, cleaning and forming of the canal during the first (one) visit?

a. to prevent aggravation in the course of treatment

b. to limit the number of visits

с. to create the apical barrier

D. to provide the optimal space for the intracanal medication

Reference literature

  1. Clincal endodontics: a textbook /Leif Tronstad.– 3rd rev. ed.– New Yourk, 2009.– 249 p.

  2. Stephen Cohen, Richard C. Burns. Pathways of the pulp. Eighth edition.– Mosby, 2002.– 1031 p.

  3. Fan B, Wu M-K, Wesselink PR. Leakage along warm gutta-percha fillings in the apical canals of curved roots. Endod Dent Traumatol 2000;16:29-33.

  4. Glosson CR, Haller RH, Brent Dove S, del Rio CE. Comparison of root canal preparations using NiTihand, NiTi engine-driven and K-flex endodontic instruments. J Endod 1995;21:146-51.

  5. Molven O, Halse A, Grung B. Surgical management of endodontic failures: indications and treatment results. Int Dent J 1991;41:33-42.

  6. Seltzer and Bender’s. Dental pulp // Quintessence Publishing, 2002.

Practical lesson No 35
Theme: Endodontic instruments. Classification. Types. Indications for use.

Short description of a theme
Endodontics is the branch of dentistry that is con­cerned with the morphology, physiology, and pathology of human dental pulp and periradicular tis­sues.Its study and practice encompass the biology of normal pulp and the etiology, diagnosis, prevention, and treatment of diseases and injuries of the pulp and associated periradicular conditions.

The scope of endodontics includes, but is not lim­ited to, the differential diagnosis and treatment of oral pain of pulpal and/or periradicular origin; vital pulp therapy, including pulp capping and pulpotomy; non-surgical treatment of root canal systems and the obtu­ration of these systems; selective surgical removal of pathological tissues resulting from pulpal pathosis; re­pair procedures related to surgical removal of patho­logical tissues; intentional replantation and replanta­tion of avulsed teeth; root-end resection, hemisection, and root resection; root-end obturation; bleaching of discolored teeth; retreatment of teeth previously treated endodontically; and treatment with posts and/or cores for coronal restorations.

The success of basic nonsurgical endodontic treat­ment is highly dependent on the triad of access cavity preparation, proper cleaning and shaping of the root canals, and the quality of the obturation of the root canal system. The long-term prognosis is determined by the quality and integrity of the coronal seal, ie, post-core-permanent restoration. It is therefore im­perative that further ingress of oral fluids (microleak-age), through restorative and endodontic materials, be kept to a minimum.

The second component of the endodontic triad in­volves cleaning and shaping of the canals. Removal of the coronal portion of the pulp is usually performed with a metallic spoon excavator or a rotary bur on a slow-speed handpiece. For the initial debridement of the canals, root canal broaches or rotary orifice-shap­ing instruments can be used. Manufactured in a num­ber of sizes, the root canal broach is a very narrow, flexible, round stainless steel instrument with barbs along its shaft. Prone to breakage, the broach must be used passively in the canal and should not engage dentin. It is designed to removed gross amounts of pul-pal tissue in large canals by locking remnants of pulp with its sharp barbs. Broaches can also be used to re­move cotton products that have been placed in the chamber between appointments.

Newer to the marketplace are rotary orifice shapers, which are made of flexible nickel-titanium. These vari­ably tapered instruments are used in special controlled-speed, high-torque handpieces. Their use in the canal is typically limited to the coronal half of the canal. Because of their larger tapers, they facilitate straight-line access to the root apex by removing restrictive coronal dentin early in the cleaning and shaping process.

Gates-Glidden instruments are commonly used to enlarge canal orifices and shape the coronal portion of the canal. Used in a slow-speed handpiece, they consist of flexible, stainless steel, noncutting shafts with flame-shaped burs at their tips. They are available in a variety of lengths and sizes.

Specially designed hand instruments known as files and reamers are necessary for biomechanical instru­mentation of the various anatomical forms of root canals. K-files are tapered metallic instru­ments made from rectangular, triangular, or rhom-boidal cross-sectional wires. They are available in stainless steel or nickel-titanium and are manufactured by twisting or grinding the metal blank. Various cut­ting angles on the wires are created to plane or scrape the walls of the canal. Depending on the file design and canal size and curvature, these files may be used in a push-pull, twisting, watch-winding, or circumferen­tial motion. The nature of the metal (nickel-titanium being five times more flexible than stainless steel), the size of the instrument, and the cross-sectional configu­ration determine the relative flexibility of each instru­ment. In order to accommodate different root lengths, these instruments are manufactured in lengths ranging from 21 to 31 mm. Moveable silicone rubber stops on the instruments can be adjusted to cor­respond to the exact length of each canal. Many newer file designs incorporate a noncutting tip, which can be used instead of a cutting tip to help guide the file. Cutting tips can create deviations in canal anatomy during instrumentation. Examples of K-type files include Flex-R files (Miltex) (triangular cross section), FlexoFiles (Dentsply) (triangular cross sec­tion), and K-Flex files (Kerr Analytic) (rhomboidal cross section).

The size of the file is determined by the diameter of the shaft 1 mm from the tip and is recorded in millime­ters. For example, a No. 25 K-file measures 0.25 mm in diameter 1 mm from its tip. The standard taper for these instruments is a 0.02-mm increase for every 1 mm up the shaft from its tip (the length of the working blades). For instance, the width of a No. 25 K-file at 16 mm above its tip is 0.57 mm (0.25 mm + 16 x 0.02 mm). Most traditional instrument designs adhere to this standard of sizing and tapering.

Another type of file is the Hedstrom file. These files are long, thin, and tapered like K-files but are made from round cross-sectional wires. Generally made from stain­less steel or nickel-titanium, these aggressive files have cutting angles that are ground into the shaft and can only be used in a scraping or rasping motion as the file moves out of the canal. Rotation of Hedstrom files is con-traindicated because they tend to self-thread and have a strong predilection toward fracture when used in this manner. Like the K-files, Hedstroms are manufactured in uniform sizes, tapers, and lengths. They are used pri­marily for removal of bulk amounts of dentin.

Classical hand root canal reamers are long, tapered, stainless steel instruments made from rectangular, tri­angular, or rhomboidal cross-sectional wires. They cut only during twisting and have fewer cutting edges than a typical K-file. Their use has diminished over time due to their lack of efficiency and their tendency to de­viate from normal root canal anatomy during use. More tapered rotary reamers made of nickel-titanium have essentially replaced the stainless steel hand reamer. These instruments have radial land-cutting re­gions along their shafts and thus have been termed "U"-bladed in cross section. Like the orifice openers previously described, rotary reamers are used in a slow-speed, high-torque, gear-reduction, air-driven or elec­tric handpiece. Their tapers range from the standard 0.02-mm increase up to a 0.12-mm increase per mil­limeter. Examples include Profiles (Dentsply), GT Ro-taries (Dentsply), Quantec 2000 (Kerr Analytic), and Lightspeed (Lightspeed).

Control questions to|by| practical lesson |occupation|

    1. What tools can be used for the root canal primary covering? Why?

    2. What tools can be used for the root canal widening? Why?

    3. What tools can be used for the obliterated root canal primary covering? Why?

    4. What is the advantage in rotary Ni-Ti endodontic tools usage?

    5. What are the indications for the use of ultra sound in endodontics? What ultrasonic endodontic tools do you know?

    6. What endodontic tools for the lateral condensation do you know? What is the algorithm of their use?

    7. What endodontic tools for vertical (hot) condensation do you know? What is the algorithm of their use?

    8. What tools are more preferable for the root canal peep-holes widening? What is the advantage?

    9. What is the indication of the endodontic tools Golden medium series in the root canal treatment.

    10. The advantages of safety usage of endodontic system in the treatment of the crooked root canal.

    11. The modern rotary Ni-Ti endodontic tool. Composition. Advantages. Disadvantages. Indication for usage. The method of application.

    12. The modern endodontic handpieces and engines. Indication for usage. Advantages. Disadvantages..

    13. Manual Ni-Ti endodontic tools. Types. Indication for usage. Advantages. Disadvantages.

    14. List all of the materials necessary for the proper placement of a rubber dam on a tooth requiring en­dodontic therapy.

    15. Discuss the types and properties of the materials used in obturating a cleaned and properly shaped root canal.

    16. Discuss the various types of instruments that can be used to bioinechanically prepare the root canal.

Situation tasks and test control
1. What endodontic tool will be used primarily and secondarily in case of manual root canal preparation?

A. К-file No15

B. К-reamer No10

C. GT-file 35/12

D. Н-file No15
2. What endodontic tool is preferable as manual in full-round root canal preparation:

A. К-file

B. К-reamer

C. ProTaper

D. Н-file
3. When is the highest risk of endodontic tool fracture in the full-round root canal preparation?

A. manual

B. Rotary speed is 200 revolutions per minute

C. Rotary with a programmed round control

D. It is important
4. For what endodontic tool a full revolution is unacceptable?

A. К-file

B. К-reamer

C. С-file

D. Н-file
5. For what endodontic tool the «balance forces» method is the most dangerous?

A. К-file

B. К-reamer

C. GT-file

D. Н-file
6. Endodontic tool of size No 10 is marked:

A. red

B. violet

C. black

D. blue

E. white

7. Endodontic tool of size No 20 is marked:

A. red

B. blue

C. yellow

D. black

E. white

8. Endodontic tool of size No 15 is marked:

A. red

B. blue

C. black

D. violet

E. white

9. Endodontic tool of size No 25 is marked:

A. red

B. blue

C. black

D. violet

E. white

10. Endodontic tool of size No 30 is marked:

A. red

B. blue

C. black

D. violet

E. white

11. Endodontic tool of size No 35 is marked:

A. red

B. blue

C. black

D. green

E. white

12. Endodontic tool of size No 40 is marked:

A. red

B. blue

C. black

D. green

E. white

13. To perform the root canal probing it should be used:

A. Miller needle

B. Н-file No15

C. К-file No10

D. H-file No15
14. All of the following endodontic instruments are de­signed to remove dentin except which one:

A. K-file

B. reamer

C. broach

D. Hedstrom
15. The endodontic "triad" consists of which of the fol­lowing:

A. access, biomechanical instrumentation, and obturation

B. rubber dam placement, access, and obturation

C. biomechanical instrumentation, obturation, and restoration

D. access, obturation, and restoration
16. All of the following are true about Hedstrom files except which one:

A. they work best by rotation

B. they are made from a circular wire

C. they are man­ufactured in uniform sizes

D. they are made from either stainless steel or nickel titanium metal
17. Which of the following is a chelating agent, helping to loosen calcific obstructions in the root canal:

A. gutta-percha

B. Roth's 801

C. sodium hypochlo-rite

18. Which of the following instruments is used in the lateral condensation of gutta-percha:

A. plugger

B. spreader

C. explorer

D. broach

Reference literature

  1. Clincal endodontics: a textbook /Leif Tronstad.– 3rd rev. ed.– New Yourk, 2009.– 249 p.

  2. Stephen Cohen, Richard C. Burns. Pathways of the pulp. Eighth edition.– Mosby, 2002.– 1031 p.

  3. Fan B, Wu M-K, Wesselink PR. Leakage along warm gutta-percha fillings in the apical canals of curved roots. Endod Dent Traumatol 2000;16:29-33.

  4. Glosson CR, Haller RH, Brent Dove S, del Rio CE. Comparison of root canal preparations using NiTihand, NiTi engine-driven and K-flex endodontic instruments. J Endod 1995;21:146-51.

  5. Molven O, Halse A, Grung B. Surgical management of endodontic failures: indications and treatment results. Int Dent J 1991;41:33-42.

  6. Seltzer and Bender’s. Dental pulp // Quintessence Publishing, 2002.

Practical lesson No 36
Theme: Work with endodontic instruments. The use of medications for cleaning of the root canal. Methods of cleaning and widening of root canals.

Short description of a theme
Regulations concerning instruments designed to aid in root canal preparation are governed by the International Standards Organization. Instruments are numbered and colour coded.

The number of each instrument refers to the diameter, Dl, of the cutting blade at the tip of the shank. The number is taken from the diameter Dl in millimetres x 100 e.g. If the diameter at Dl is 0.25 mm the number of the instrument is 25. D2 is the diameter of the cutting blade furthest from the tip of the shank. The working part, which lies between Dl and D2, is tapered, the degree of taper depending on the type of instrument. Reamers and files have a taper of 0.02 mm per mm of working length.

Colour coding. The International Standards Organization (ISO) recommends a colour coding system which has now been adopted by the majority of firms manufacturing hand instruments, six colours were chosen in ascending order of size from light to dark. These colours are repeated in each of the 3 groups. The table on the right shows the range of numbered instruments and their allotted colour coding.

Instrument lengths. There are four standard lengths manufactured 21 mm, 25 mm, 28 mm, and 31 mm measured from the instrument tip to the base of the handle. These lengths are adequate for the majority of teeth but occasionally longer than 31 mm may be required and these can be ordered specially.

Types of instrument. The various types of instrument in use are illustrated, including several of the more recent designs. Some instruments such as the smooth broach and rat tail files are rarely used and are not described.

Barbed broach. These instruments are designed to remove gross pulp tissue. They are made from soft steel and have barbs notched into the shank. They must only be used in the straight part of the canal. The size chosen should fit loosely into the canal to avoid breakage. Reamer. The reamer is produced by twisting a square or triangular tapered blank. A reamer will cut only when it is rotated due to the angle of the blade or flute.

K-File. The K-file received its name from the Kerr Manufacturing Co., who were the first to produce it. The K-file is constructed in the same way as a reamer except that there are 2% times the number of twists per unit length. The advantage of the file is that it may be used to -cut dentine by either a rotary movement or a filing action.

Flex-O-File2. A recent addition, the Flex-O-File is very similar to a K-file but is manufactured with a softer more flexible steel. It does not fracture easily and is so flexible that it is possible to tie a knot in the shank.

K-Flexfilel. Another recent addition to the range of hand instruments. It is similar to a K-file except that the shape of the cross section is a diamond. This means that the instrument is more flexible than a reamer or K-file and has a sharper blade. Hedstroemfile. The instruments are machined from a round tapered blank. A spiral groove is cut into the shank, producing a sharp blade. Because of the angle of the blade the hedstroem file should only be used with a filing action. If a rotary movement is used and the blades engage the dentine there is a danger of the instrument fracturing. Unifile. This relatively new instrument is almost identical in appearance to the hedstroem file, but it has two cutting blades instead of one. The grooves cut into the shank of the Unifile remain at the same depth throughout the working part. This increases the stiffness and resistance to fracture in the coronal and middle thirds of the instrument but allows greater flexibility in the apical portion which corresponds to the position of the curve in most roots.

Helifile. The method of manufacture of the Helifile is similar to the Hedstroem and Unifile except that in cross section there are 3 blades. The appearance of the instrument resembles a reamer rather than a Hedstroem file. Little information is available yet concerning their cutting ability or resistance to fracture.

Instrument Safety and Usage. An ever present danger during root canal preparation is the fracture of an instrument within the canal. This will be unlikely to occur if the following steps are taken.

1. Instruments should be inspected before they are inserted into the root canal. If there is any sign of the flutes becoming either unwound or overtwisted the instrument should be discarded. Instruments with a sharp bend in the shank should also be thrown away. There is no guide to the number of times an instrument should be used as this will depend upon a number of factors. Smaller instruments will be discarded more frequently than larger ones.

2. Never force an instrument into a canal. If an instrument feels tight in the canal short of the working length it should be removed and a smaller size used.

3. Reaming action. All instruments with the exception of the Hedstroem file may be used with a reaming action. The reaming action consists of a quarter to a half turn and withdrawal. An instrument should not be screwed into the canal as this invites fracture. The reaming action produces a rounder hole than filing but should not be used in curved canals as it will produce zipping in the apical portion of the canal.

4. Filing action is carried out by inserting the instrument to the marked depth and then withdrawing it while exerting even pressure on the wall of the canal. The instrument is withdrawn a few mm, reinserted and the movement repeated. The entire wall of the canal is filed by gradually working circumferentially in a clockwise direction.

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