`PRESENTED TO:

DR.NAEF & DR.BASEM ABU-QUBO'PREPARED BY:

MOHAMMAD SALAH QREA‘FIFTH YEAR DENTISTRY

2007\2008

Main menu MODERN ENDODONTICS

HISTORY OF ULTRASONICS

ULTRASOUND

ULTRASOUND PRODUCTION

MAGNETOSTRICTION

PEIZOELECTRIC PRINCIPLE

APPLICATIONS OF US

Modern endodontics!• The use of microscopes and ultrasonics

(US) in endodontics increases the quality of the treatment, and represent an important adjunct in the treatment of difficult cases.

History of the US • The use of ultrasonics (US) was first

introduced to dentistry for cavity preparations.

• In 1955 US was introduced for calculus removal.

• The concept of using US in endodontics was first introduced by Richman in 1957.

Ultrasound

• Ultrasound is sound energy with a frequency above the range of human hearing, which is 20 kHz. The range of frequencies employed in the original ultrasonic units was between 25 and 40 kHz.

Ultrasound production

• There are two basic methods of producing ultrasound:

• The first is Magnetostriction.

• The second is Piezoelectric.

Magnetostriction• Converts electromagnetic energy to

mechanical energy.

• A stack of magnetostrictive metal strips in a handpiece is subjected to a standing and alternating magnetic field, as a result of which vibrations are produced.

Piezoelectric principle

Crystals mechanical oscillation

Electrical charge

Magnetostriction .Vs. Piezoelectric

Category Magnetosriction Piezoelectric

Cycles/ sec.24 KHz40 KHz

Heat generationRequires cooling system

No heat generation

Lines of actionFigure of eight & elliptical.

Linear, back & forth.

Applications of US in Endodontics

Access Irrigation

Intracanal obstruction

Gutta Percha

MTA

Surgical endodontics

Root canal preparation

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Access Refinement, Finding Calcified Canals, and Removal

of Attached Pulp Stones

When do we use US for access?• Orifices occluded by secondary dentin or

in calcified dentin.

• A lack of a straight-line access leading to separation, perforation, and the inability to negotiate files to the radiographic terminus.

• In difficult-to-treat teeth such as molars.

• Calcified canals and pulp stones.

Advantages of US

• They do not rotate enhancing control, cutting, and safety.

• The most convenient tool for removing secondary dentin, while searching for hidden canals.

US tips• A troughing tip is a good choice for

removing calcified dentin over orifices.

• Bigger tips with a limited diamond coated extension should be used during the initial phase of removing calcification, interferences, materials, and secondary dentin, as they offer maximum cutting efficiency and enhance control while working in the pulp chamber

US tips• Thinner and longer tips that facilitate

working in deeper areas while maintaining clear vision, should be used in subsequent phase of finding canal orifices.

• The diamond-coated tips used in orthograde endodontic treatment have shown significantly greater cutting efficiency than either stainless steel tips or zirconium nitride coated tips, but they have a tendency to break.

• Thinner diamond-coated tips seem to make more aggressive cutting action, so that care should be exercised while searching for canal orifices.

US tips

BUC

(a) The BUC-1 is an example of diamond-coated spreader tip of medium length that can be used for gross dentin removal, moving access line angles, cutting a groove in the mesial access wall to drop into MB2 canals, and quickly and carefully unroofing pulp chambers.

(b) The BUC-3 is similar to the BUC-1 with a sharper tip and a water port for increased washing and cooling of the operative site. It is used for chasing canals or for digging around a post or carrier-based obturator with the objective to remove it.

(c) This diamond-coated pear tip is used to find canals, remove coronal obstructions or restorative materials, or remove calcifications,temporary and permanent cements, and posts. It creates a smooth, clean flat troughing groove that facilitates canal location.

(d) This diamond-coated ball tip provides fine cutting control when preparing a troughing groove and is less aggressive than the pear tip shown in c, yet it has the same clinical indications.

)e (A classic spreadertip with a diamond coating, which offers a side- as well as an end-cutting action. This is needed to flare the walls of a troughing groove in an axial direction.

)f (A fine spreader tip indicated for troughing and removal of broken instruments.

)g (An extra-fine spreader tip used for extremely fine and deep troughing or removal of aseparated instrument in the middle or apical third of the canal.

)h (A spreader tip designed for multiple uses such as instrument or silver point removal, troughing , removal of calcifications, provisionals, cements, buildup materials, etc.

SINE

Figure 1. The orifice of the second mesio-buccal canal (MB2) in an upper firstmolar was located (a) and enlarged (b). Dentine spur at the orifice was effectivelyeliminated with the use of a diamond-coated ultrasonic tip, thus permittingeasy location of the orifice of the canal.

Removal of intracanal obstructions

Intracanal obstruction

• Separated Instruments.

• Root Canal Posts.

• Silver Points and Fractured Metallic Posts.

• Removing of the rotary instruments.

Management of broken instruments• Surgical approach.• Orthograde:• (a) attempt to remove the instrument; • (b) attempt to bypass the instrument; • And (c) prepare and obturate to the fractured

segment.• In many cases the removal of fragments is

hopeless, and cause several complication:

include excessive loss of root canal dentin, ledging, perforation, and extrusion of the fractured instrument fragment through the apex

• For example: “staging platform” using Gates Glidden drills (size 3 or 4) , cause weakening of the root wall and may cause perforation.

• Recently, it has been shown that preparation of staging platforms was best accomplished with the use of modified Light Speed files .

• The inability to see the instrument with direct vision and the difficulty of creating a staging platform, as well as the use of US in curved roots, has contributed to a lack of success in removing fractured instruments.

Gates Glidden bur modified by cutting it at the maximum diameterviewed from an apical (a) and lateral direction (b). This permits the preparationof a platform at the extruded portion of the fragment to be removed.

NiTi rotary instrument separated in the distobuccal canal of an upper first molar

The fragment was removed using ultrasonic tips, and the root canals were successfully negotiated to the apex

cleaned, shaped, and filled tooth

Root Canal Posts

• US reduce the amount of tooth structure loss.

• The preservation of maximum root structure requires the use of specific ultrasonic tips.

• There are some challenges.

Challenges

• fiber-reinforced composite posts cemented with adhesive systems.

• Esthetic white posts.

Removing of posts• Removal is done in a dry field using a

continuous stream of air with direct vision of the ultrasonic tip and the coronal portion of the post.

• It is important that the entire composite material that was used in the luting procedure be removed.

)i (Vibrator tip specifically designed for post removal.

• Adhesive material.

• “Gray streaks” evidence.

• Composite resin cements causes a change in the effectiveness of US as an aid in post removal.

• No water…better US!!! (resin cements).

• As the mod. Of elasticity increase the effectiveness of the US increase." stainless steel”.

How to remove?

• Removal of restorative materials and luting cement around the post, followed by application of the tip of an ultrasonic instrument to the post.

• This method of post removal minimizes loss of tooth structure and decreases the risk of tooth damage.

• The tip should not be too thin, because small-diameter ultrasonic instruments are weak and more predisposed to breakage, On the other hand, the tip should not be too large, because it must be kept in intimate contact with the post.

• Adequate water-spray cooling.

• In prefabricated posts it is easy to separate the coronal portion.

• Clinically, after removing all circumferential restorative materials, the majority of posts can be safely and successfully removed within approximately 10 minutes.

Preoperative image (a) and radiograph (b)

The metal-ceramic crown was sectioned (c) and removed (d),

The gold cast posts were separated to facilitate their removal (e, f).

The three posts were removed (g) by vibrating with an ultrasonic tip to disrupt the cement seal

This clinical image revealed two perforations in the mesial root canal (h).

Perforations were repaired using gray MTA compacted with an ultrasonic tip (i). Root canals were filled with gutta-percha and sealer (l).

Post-endodontic pre-prosthetic restoration was performed using a fiber-reinforced post in the distal canal and a dual-cure resin composite buildup material (n).

Silver Points and Fractured Metallic Posts

• Exposing the coronal part of the obstacle by cutting an estimated 2.0-mm around the obstacle with a fine diamond bur.

• The tip of an ultrasonic unit is then applied to the side of the post fragment at full power with water irrigation, then can be removed by fine forceps.

• Large-diameter posts are more time consuming compared with narrow ones

Removing of the rotary in steps.

• A radiograph.• After straight-line access to all canals.• radicular access to the obstruction• If radicular access is limited, rotary nickel-

titanium or hand files are used to create sufficient space to safely introduce Gates Glidden drills into the canal orifice.

• These Gates Glidden drills are then used in a brush-like manner to create additional space and allow maximum visibility of the obstruction.

• Good visualization.

• Staging platform.

• then the use of US is indicated to remove dentin just around the fractured instrument, to loose it within the canal.

Increased Action of Irrigating Solutions

Irrigation • Mechanical + chemical.

• US can reach difficult anatomy, irrigant vibration, and cleaning of the canal space.

• US creates both cavitation and acoustic streaming.

• Antibacterial effects (shear stress).

• There is a synergistic effect between sodium hypochlorite (NaOCl) and US.( NaOCl loves heat)

Acoustic streaming around a file in free water (left) and a schematic drawing (right).

• Ultrasonic vibration can also be effective when touching the shank of a hand file inserted inside the canal. The hand file will transmit vibrations to the irrigant inside the canal, but a greater risk for touching dentinal walls exists.

• The use of a smooth wire during ultrasonic irrigation in vitro was as effective as a K-file in debris removal, and with EDTA it enhances the cleanliness of the canal.

Representative SEM photomicrographs.(2mm from the apex) Specimens with (A) smear score 0 and debris score 0, (B) smear score 1 and debris score 1, and (C) smear score 2 and debris score 2

17% EDTA+ ultrasonic Ultrasonic followed by NaOCl 1%

1% NaOCl for 1 min. followed by 1% NaOCl

Ultrasonic Condensation of Gutta-Percha

• Ultrasonically activated spreaders have been used to thermoplasticize gutta-percha in a warm lateral condensation technique.

• A more homogeneous mass, less voids, 3D obturation.

US & obturation

Obturation protocols • (a) Ultrasonic softening of the master cone

followed by cold lateral condensation .

• (b) One or two times of ultrasonic activation after completion of cold lateral condensation.

• (c) Ultrasonic activation after placement of each second accessory cone.

• (d) Ultrasonic activation after placement of each accessory cone.

Recommended Obturation technique

• Initial placement of a gutta-percha cone to the working length.

• Followed by lateral condensation of two or three accessory cones using a finger spreader.

• The ultrasonic spreader is then placed into the center of the gutta-percha mass 1 mm short of the working length and activated at intermediate power.

• After activation, the ultrasonic spreader is removed, and an additional accessory cone is placed, followed by energizing with the activated ultrasonic spreader.

• The spreader must be in a canal only 10 sec.

• Using a sealer with US gives the best results.

Root canals were filled with gutta-percha and sealer

Placement of Mineral Trioxide Aggregate (MTA)

MTA & US

• Placement of MTA with ultrasonic vibration and an endodontic condenser improved the flow, settling, and compaction of MTA, denser, with few voids.

Technique • The recommended placement method

consists of selecting a condenser tip, then picking up and placing the MTA with the ultrasonic tip, followed by activating the tip and slowly moving the MTA material down using a 1- to 2-mm vertical packing motion. Direct ultrasonic energy will vibrate and generate a wavelike motion, which facilitates moving and adapting the cement to the canal walls.

Perforations were repaired using gray MTA compacted with an ultrasonic tip

The coronal portions of the mesial canals were further filled with MTA to enhance the seal of the perforations

Apical to the canal curvature • Placing MTA with trimmed G.P. as plugger.

• A precurved 15 or 20 stainless steel file is then inserted into the material.

• This is followed by indirect ultrasound.

• This technique can be used also in:• Open and diverging apices, in perforations and

especially in perforations of the floor of the pulp chamber, and in root-end cavities.

Surgical Endodontics: Root-End Cavity Preparation and

Refinement and Placement of Root-End Obturation Material

Conventional root-end cavity preparation

• Using rotary burs in a microhandpiece is faced with several problems, such as a cavity preparation not being parallel to the canal, difficult access to the root end, and risk of lingual perforation of the root.

• Furthermore, the inability to prepare to a sufficient depth “retention”.

Ultrasonic and sonic retro-tips

• Better access to the root end.

• Ultrasonic retro-tips come in a variety of shapes and angles.

• Less smear layer, and more conservative.

• YAG lasers have been shown to produce significantly lower micro-leakage than ultrasonic preparations.

Diamond tips for surgical endodontics

• Satelec.

• Trinity.

• CVD. new

Designs of the tips• ↑angulation of retro-tips ↑the transverse

oscillation and ↓the longitudinal oscillation, putting the greatest strain at the bend of the instrument.

• Straighter design will restrict access and a thicker instrument prevents instrumentation of isthmuses.

• Preparation with smooth stainless steel tips produced fewer intra-dentin cracks than diamond-coated stainless steel tips and sonic diamond-coated tips.

Diamond-coated stainless steel ultrasonic surgical retro-tips.

Smooth stainless steel ultrasonic surgical retro-tips.

The KiS® microsurgical ultrasonic instruments by Spartan are designed for use in endodontic

microsurgery .

Procedure • It has also been suggested that root-end cavities

should be initiated with a diamond-coated retro-tip, using its better cutting ability to provide the main cavity.

• A smooth retro-tip to smooth and clean cavity walls.

• A condenser tip.• Ultrasonic tips can also be used to polish root

end material and apical surfaces.• Ultrasonic tips for refinement may be beneficial in

the elimination of extraradicular bacteria

The success

• Apical resorption after healing may eliminate the surface defects and contribute to the overall success of treatment, that may be removed by finishing resected.

• It is recommended that the ultrasonic unit be set at medium power and the cavities be prepared to a depth of 2.5-3 mm.

Root Canal Preparation

Canals preparation & US

• Several studies have shown that ultrasonically or sonically prepared teeth have significantly cleaner canals than teeth prepared by hand instruments.

• There is a relative inefficiency of US in debridment of the canals, so we can used it not as initial instrument but with handle files to give the best results.

In conclusion• As a result, access refinement, location of

calcified canals, and removal of separated instruments or posts have generated more predictable results. In addition, better action of irrigation solutions and condensation of gutta-percha have benefited from the use of US.

• Finally, integration of new technologies such as US, leading to improved techniques and use of materials, has changed the way endodontics is being practiced today.

REFERENCES• Gianluca Plotino, Ultrasonics in Endodontics: A Review of the

Literature, JOE — Volume 33, Number 2, February 2007, P (81-95).

• Ahmed Abdel Rahman Hashem, Ultrasonic Vibration: Temperature Rise on External Root Surface during Broken Instrument Removal, JOE—Volume 33, Number 9, September 2007, P (1070-1073).

• Keith Carver, In Vivo Antibacterial Efficacy of Ultrasound after Hand and Rotary Instrumentation in Human Mandibular Molars, JOE—Volume 33, Number 9, September 2007, P (1038-1043).

• John T. Dominici, Analysis of Heat Generation Using Ultrasonic Vibration for Post Removal, Journal of Endodontics: 31 Issue: 4, April, 2005, p (301-303).

• L. W. M. van der Sluis, Passive ultrasonic irrigation of the root canal: a

review of the literature, International Endodontic Journal, 40, 415–426, 2007.

• Yoshitsugu Terauchi, Evaluation of the Efficiency of a New File Removal System in Comparison With Two Conventional Systems, JOE — Volume 33, Number 5, May 2007.

• Ricardo A. Bernardes, Evaluation of Apical Cavity Preparation With a New Type of Ultrasonic Diamond Tip, JOE—Volume 33, Number 4, April 2007.

• Jeen-Nee Lui, Effect of EDTA with and without Surfactants or Ultrasonics on Removal of Smear Layer, JOE—Volume 33, Number 4, April 2007.

And ……………… THANK YOU