1. Cleaning and Shaping
Dr. Hadil Abdallah Altilbani

2. CLEANING
Debridement
Debridement is the removal of existing or potential irritants from the root canal system

3. The goal is elimination; in actual practice, there is usually only a significant reduction.
These irritants consist of the following, either singly or in combination:
Bacteria, bacterial byproducts, necrotic tissue, organic debris, vital tissue, salivary byproducts, hemorrhage, and other contaminants.

4. Technique
Ideally, instruments contact and plane all walls to loosen debris.

6. The chemical action of irrigants
Further dissolves organic remnants and destroys microorganisms.
Irrigants then flush the loosened and suspended debris from the canal space. Despite a practitioner's best efforts, remnants usually persist after the most careful chemomechanical preparation of the canal .

9. The use of irrigating solutions is an important part of effective chemomechanical preparation.
Antibacterial agent.
Tissue solvent.
Flush debris.
Lubricant.
Eliminate the smear layer.

10. The most common intracanal irrigant used is sodium hypochlorite.
It is inexpensive, readily available, and highly antimicrobial, and has valuable tissuedissolving properties.

11. Irrigation
This is sodium hypochlorite in a concentration of either 5.25 or 2.5%.
It acts as a medium to dissolve and flush organic debris and bacterial products out of the root canal system, as well as functioning as a lubricant and antibacterial agent.

13. “The effectiveness of low concentrations of NaOCl may be improved by using larger volumes of irrigant or by the presence of replenished irrigant in the canals for longer periods of time.”

14. The volume of solution used is probably more important than the concentration.

16. CLEANING So, realistically, the objectives are :
to reduce these irritants to a subsignificant level
to obturate so that the remnants are sequestered within the canal.

17. Limitations
The root canal system is a very difficult environment in which to operate.
To reemphasize an important concept, files must contact and plane the walls to debride effectively Such contact is often impossible owing to the design and physical properties of instruments and the irregularities of the pulp system.

19. SHAPING

20. Schilder' outlined the principles of shaping as follows:
To develop a continuously shaped conical form from apical to coronal.
The apical preparation should be as small as is practical and in its original position spatially.
In addition, removal of a uniform layer of dentin in all dimensions and all regions of the canal is also desirable.

22. Enlargement

23. The canal should be enlarged enough to permit adequate debridement as well as manipulation and control of obturating materials and instruments, but not so much that the chances of making procedural errors and needlessly weakening the root are increased.

26. Taper

27. Increase in diameter per unit length
Definition:
Increase in diameter per unit length

28. Generally, taper should be sufficient to permit deep penetration of spreaders or pluggers when obturating with gutta-percha. Excessive taper may result in unnecessary removal of dentin and weakening of the root.

30. Adequate shaping basically reflects adequacy of preparation for obturation.
That is, whether the technique is lateral or vertical condensation, the canal must be flared and enlarged to permit control and to achieve adequate depth for spreader or plugger insertion during obturation."

32. To test adequacy, selected obturating instruments are "tried-in" during canal shaping.
When taper is sufficient to permit spreader penetration deep into the canal (0 to 1 mm from the apical stop) with some space adjacent for gutta-percha, the flare is adequate With lateral condensation, the deeper the spreader penetrates during its initial insertion alongside the guttapercha, the better the apical seal."
With vertical condensation, sufficient flare is required to allow placement of pluggers within 3 to 5 mm of working length.

35. Cleaning and Shaping

36. Clinical Objetives: ¨ Pretreatment – ensure restorability
“Start with the end in mind”
¨ Pretreatment – ensure restorability
¨ Access for Success – remove the pulpal roof entirely, obtain straight line access, visualize all orifices without moving the mouth mirror, achieve axial walls with adequate taper and access the canals.
Ruddle C. Cleaning and shaping the root canal system. In Cohen S, Burns RC (eds).
Pathways of the pulp. 8th ed. St. Louis: CV Mosby Company, 2002:

37. Mechanical Objectives:
¨ Continuously tapering preparation from the chamber to the foramen.
¨ Maintain original anatomy, consider curvatures and root concavities.
¨ Maintain the position of the foramen.
¨ Keep the foramen as small as practical.

38. MASTER APICAL FILE
DETERMINATION

39. The master apical file (MAF) is by definition the largest file that binds slightly at the corrected working length.
The MAF is determined by passively placing successively larger files at the correct working length until a size is reached that slightly binds at the tip. This determination is made after straight-line access .

41. Canal Preparation Techniques

43. The Step-Back Technique
Telescopic or serial root canal preparation
It was first described by Clem" in 1969

44. In this technique apical portion is instrumented first and then progress toward coronal.

45. This instrumentation technique forms an apical stop and thereby avoids irritation of the periapical tissues by medicaments or filling material. Because there is very little canal enlargement and removal of dentin near the apex, the danger of perforation is reduced.

47. (the initial apical file (IAF).
After the access opening is made, the working length is determined on a measurement radiograph.
The first file that binds in the canal at the working length is considered
(the initial apical file (IAF).

50. At the beginning of instrumentation, the length of the canal and the size of the initial apical file (IAF) are determined on a radiograph.
Starting with the IAF, the root canal is enlarged to the working length through four file sizes.

51. K files are used exclusively in this preparation technique.
During this initial phase of preparation, no instrument sizes may be skipped or a blockage may be created.
K files are used exclusively in this preparation technique.

52. Master Apical File
The largest file that extends to working length is the Master Apical file (MAF)
For large canals – minimum MAF #
For small canals – minimum MAF #

53. Take a radiograph with MAF in place. This confirms:
Length
Placement

54. Step-back technique
After the root canal has been enlarged throughout its entire length to the size of
the apical master file
The subsequent files are each made 1 mm shorter than the previous file.

57. Irrigation Recapitulation
This is accomplished, after each successively larger file, by irrigating and then returning to a file smaller than the file which prepared the apical portion of the canal
Irrigation
is used between each file also to remove debris.
Failure to recapitulate will result in canal blockage. Frequently blockage can be difficult to clear and attempts to do so may result in a ledge or even perforation

58. Recapitulation-
The follow-up cleaning action of returning full length with a smaller sized instrument to remove the dentinal debris that forms as the body of the canal is being shaped with larger instruments.
……….returning frequently with the first instrument to break up and remove any chips or debris forming in
the apical curve.

59. The advantages of this technique are:
(1)less possibility of perforation or ledging,
(2)uniform enlargement of irregularly shaped canals,
(3)better debridement,
(4)savings in operator time, and
(5)obturation with gutta percha in severly curved canals, with the exaggerated taper permitting greater compressipon of the gutta percha in the apical portion of the canal.

60. Copious irrigation should accompany the filing, as should recapitulation with the smaller apical instrument, to ensure that the cavity is not clogged with debris.

64. Apical patency
A patency file is a small flexible instrument (08, 10) that will move passively through the terminus of a root canal without binding or enlarging the apical constricture.
The aim is to prevent apical blockage, which will, in turn, reduce the incidence of ledge formation and transportation of the root canal.
The use of a patency file also helps remove vital or necrotic pulpal remnants from the end of the canal.

65. Establishment of patency