Conclusion and Final Remarks

Treatment must have a goal and the path to that goal must be based upon the best scientific evidence available. What then are the goals of root canal treatment? The principle goal is the control of infection, be it the elimination of microorganisms from an infected root canal system or the prevention of root canal infection in a tooth that has been successfully treated. The prospects for maintaining the health of the tissues surrounding a treated tooth are also influenced by the nature and quality of the procedures used in restoring the tooth to function. The challenges facing the clinician in achieving these goals however are often hampered by the form (biofilm) and pervasive nature of root canal infection, the complex anatomy in which it exists, and the limitations of the technology currently available to the clinician who routinely addresses these issues. Mainstream endodontic treatment is still based upon the use of metal instruments to clean and shape the principle canals of the root canal sys-

B. Basrani, DDS, MSc, RCDC (F), PhD Associate Professor, Director M.Sc. Endodontics

Program, Faculty of Dentistry, University of Toronto, 348C-124 Edward Street, Toronto, ON M5G1G6, Canada e-mail: Bettina.Basrani@dentistry.utoronto.ca

tem and the disinfecting agents used to address infection that is left behind in the main canal and present in areas unreachable by the cleaning and shaping instruments.

The effectiveness of root canal cleaning and shaping has been improved over the years through the introduction of different instrument shapes and the use of more versatile metals and alloys that were not available in the past. It has been an exciting time in endodontics as new instruments, new alloys, and new modalities of instrumentation came on market to allow preparation of canals that at one time were considered untreatable because of their anatomy. Unfortunately, while the selection of teeth for treatment broadened, the prognosis for success subsequent to their treatment remained the same. Studies have repeatedly shown that even when using state-of-the-art instruments, motors, and devices, biofilm still remains on the walls of the main areas of the root canal and in the irregularities and complex pathways of its anatomy. It is as obvious today as it was many years ago that means other than the mechanical preparation of the root canal system are necessary to reduce and hopefully eliminate a microbial presence or, as stated in terms of our treatment goals, to eliminate the presence of microorganisms.

Over the years various agents and combination of agents have been used to augment disinfection of the root canal. Interestingly, sodium hypochlorite first introduced over a half century ago has remained the most effective and consequently the most widely used. Despite its effectiveness however, microorganisms still remain, be they in significantly reduced concentrations after use. This is not to say that other agents have not been introduced to augment mechanical preparation of the root canal and it is not surprising that some are currently in use. Chlorhexidine, MTAD, and other proprietary solutions, for example, have been used and are still being used as an adjunct in treatment. The same might be said for interappointment dressings. None however have proven themselves to be more effective or yield a more favorable treatment outcome to than sodium hypochlorite when used alone. The fact that microorganisms continue to persist in the root canal after treatment indicates that while we have been able to successfully treat many more types of teeth, we have not been successful in achieving the intended treatment goal of routine and predictable root canal sterility.

This has not remained unaddressed. As this textbook goes to press, new and exciting methods of root canal irrigation and disinfection are being developed for use in endodontic treatment. These vary from new methods in the delivery of NaOCl, and new methods of NaOCl activation, to improve its anti-biofilm activity and to extend its antimicrobial action to otherwise unreachable areas of the root canal. Innovative researches using lasers and photoactivated nanoparticles for root canal disinfection are also being tried and have also shown some measure of promise. So what does the future hold for the next generation of endodontic clinicians? Will these new methods be simply a variation of the current approach to root canal irrigation with NaOCl, or will they be a vastly different technology that does not rely on NaOCl. Will the treatment outcome be the same, or will it show significant improvement? Only time will tell. Another question remains as to whether these new technologies can be readily incorporated into endodontic practice with the same ease and expense as are the methods of root canal irrigation being used today. As an optimist,

I have every expectation that something better than what we currently use will become available and that, with its or their introduction, our ability to eliminate microorganisms from the root canal will improve. Ultimately we will move closer to achieving our goal and ultimately we will witness a rise in treatment outcome.

Dr. Shimon Friedman, in a lecture delivered at the 2014 American Association of Endodontists’ annual meeting, said that when new technologies come on the market, they fall into 2 categories:

(1) those that claim to facilitate treatment (with no impact on outcome) and (2) those that claim to improve the outcome of treatment for the patients. The 1st category includes the use of apex locators, microscopes, motor-driven endodontic instruments, etc. These improvements make our work as endodontists easier and more predictable. The 2nd category includes the use of MTA for sealing of perforations or in inducing apexification, where clinical evidence has shown that the prognosis of treatment has improved. All these devices, instruments, and materials that either improve our comfort as practitioners or improve the outcome for patients can be incorporated to the clinical practice without delay.

But what about the enhanced irrigation devices described in this chapter? Which category do they fall into? Unfortunately, there is not enough clinical evidence to currently support their use with a better outcome. Perhaps our current ways of measuring the outcome are not sensitive enough to measure the changes that may occur. Maybe the sample size is too small for the type of interventional research that is needed to show a difference, or maybe none of the irrigation enhanced modality is significantly better than sodium hypochlorite in a handheld syringe. Logic suggests that if these irrigation devices are making our irrigation procedure easier without causing harm to the patient, there is nothing wrong with incorporating into practice now. But if we are looking for an improvement in the outcome of treatment of apical periodontitis, we will have to wait for evidence derived from blinded and controlled from clinical studies.

Acknowledgement I would like to thank Dr. Calvin Torneck for his feedback in writing this chapter.

A

Accumulated debris, 66, 70, 71, 99, 138

Acoustic streaming, 176–179, 182, 187, 204, 230, 232 Activation, 35, 59, 60, 84, 85, 103, 109, 112, 150, 152,

153, 158, 175–180, 183, 186–191, 200, 208, 227–234, 243, 247, 278, 308, 314

Agitation, 46, 59, 60, 68, 75, 78, 84, 144, 151–154, 158, 164, 186–191, 204, 217, 232

Anatomical complexities, 25, 34, 99–100 ANP. See Apical negative pressure (ANP)

Antimicrobial, 2, 66, 100, 165, 222, 228, 238, 254, 269, 294, 306, 314

Antiseptic solutions, 101–103, 276

Apical negative pressure (ANP), 85, 112, 123, 129, 131, 133, 150–153, 157–169, 307

Apical periodontitis, 7, 10, 11, 46, 60, 71, 72, 77, 80, 81, 99, 105, 117, 132, 137, 144, 149, 165, 261, 262, 267, 268, 272–274, 277, 301, 309, 314

Apical size, 53, 88, 121, 140, 151, 181 Apical vapor lock, 58–59, 82, 133, 150, 186

B

Biofilm, 1, 34, 46, 66, 100, 117, 140, 151, 165, 175, 200, 224, 227, 237, 258, 268, 286, 313

C

Calcium hydroxide (Ca(OH)2), 7, 67, 73, 102, 167, 175, 180, 183, 185, 187, 189–191, 259, 261, 262, 269–278, 295, 301, 308, 309

Cavitation, 84, 109, 176–179, 182, 183, 187 Chemical debridement, 133, 168, 175, 302–303,

306, 308

Chlorhexidine gluconate (CHX), 67, 73, 78–80, 103–112, 256–258, 274, 276, 277, 296, 303, 307

Cytotoxicity, 118, 133, 167, 224, 259, 271, 292, 294

D

Debris removal, 16, 66, 163–165, 181–183, 185, 187, 189, 190, 233

Decalcifying agents, 105, 111, 295

Dental anatomy, 20

Dentin constituents, 99, 100

Dentin matrix, 73, 100, 166, 244, 258, 259, 277, 303–307

Dentin structure, 99, 100, 108

Dentistry, 126, 179, 222, 225, 228, 229, 231, 254, 269 Disinfection, 34, 47, 60, 66–68, 70–72, 75, 83, 85, 99,

100, 102, 104, 105, 111, 112, 133, 151, 153, 159, 173, 175, 176, 186, 187, 191, 208, 212, 227, 228, 230, 232, 233, 237–248, 254, 257, 262, 263, 268, 269, 271, 272, 274, 277, 285–296, 302, 307–310, 314

E

EDTA. See Ethylenediaminetetraacetic acid (EDTA) Endodontic debridement, 157–158

Endodontic irrigation, 68, 83, 84, 87, 99–112, 117–133, 151, 159, 167, 188

Endodontics, 2, 15, 45, 66, 99, 117, 137, 149, 157, 173, 200, 223, 228, 241, 254, 267, 285, 301, 313

Endodontic therapy, 17, 66, 132, 137–146, 183, 191, 242, 271–273, 286, 292, 302

Endodontic treatment, 7, 66, 71, 77, 84, 99, 105, 118, 121, 132, 133, 149, 157, 168, 169, 199–200, 207, 209, 223, 231, 242, 267, 268, 278, 285, 288, 289, 294–296, 302, 313, 314

EndoVac system, 133, 159–161, 163–169, 185 Ethylenediaminetetraacetic acid (EDTA), 73, 74, 78, 82,

105–112, 153, 163, 182, 187, 188, 190, 207–209, 233, 257–260, 263, 295–296, 302–309

F

Flow, 34, 46, 74, 110, 127, 141, 152, 158, 175, 200, 228, 309

Fluid dynamics, 45–60, 66, 74, 85–88, 127, 128, 164, 232

Flushing techniques, 158

Foramen, 16, 22–24, 26, 30, 31, 51, 59, 85, 118, 119, 121, 124, 125, 127, 128, 138–140, 142–146, 152, 164, 166, 204, 206, 207, 228, 261, 286, 294, 295, 309

H

HEBP, 105, 108–109

I

Insertion depth, 52, 53, 56, 58, 150

Intracanal medication, 104, 254, 255, 262, 267–278, 295, 308, 309

Irrigant delivery, 35, 45, 50, 75, 85, 119, 127, 128, 130, 162, 164, 182

Irrigants, 34, 45, 66, 100, 118, 137, 149, 158, 173, 199, 230, 244, 254, 268, 295, 302

Irrigation, 10, 34, 45, 65, 99, 117, 140, 149, 157, 173, 199, 224, 227, 242, 254, 268, 287, 301, 314

Irrigation techniques, 35, 45, 70, 82, 158, 168, 190, 191, 228, 230, 307–308

Isthmus, 21, 25–28, 30, 34, 60, 66, 70–71, 85, 99, 100, 130, 142, 152, 158, 159, 162–164, 167, 173, 175, 181–185, 189, 190, 200, 204, 209, 212–215, 227, 230, 233, 234, 268, 269, 290, 291

L

Laser, 8–10, 69, 72, 80–82, 87, 112, 151, 186–188, 191, 227–234, 242, 243, 245–248, 256, 295, 314

M

Manual dynamic activation (MDA), 149–154 Master cone, 151–153, 200, 203

Maxillary sinus considerations, 120–121 Microbial control, 117–118, 165–166, 302

Micro-computed tomography (µCT), 23, 25, 26, 28, 69, 71, 291, 294

Minimally invasive, 200, 203–204

N

Nanoparticles, 100, 105, 243, 244, 246, 247, 314

Needle, 36, 45, 70, 118, 140, 150, 158, 173, 199, 229,

295, 309

O

Oval canals, 69, 199, 200, 204, 208, 211–214 Ozone, 183, 221–225

P

Patency file, 137–146, 151 Photodynamic therapy, 237–248

Photon induced photo-acoustic streaming (PIPS), 151, 187, 191, 227–234

PIPS PROTOCOL, 233–234

Q

QMiX, 110–112, 153

R

Refreshment, 46, 47, 51, 53–58, 109

Regenerative endodontic procedures (REPSs), 301–310 Retreatment, 19, 105, 214–216, 243, 267, 268, 277,

285–296

Root canal, 2, 15, 45, 66, 99, 117, 137, 149, 157, 173, 199, 223, 227, 237, 253, 267, 285, 302, 313

anatomy, 15–36, 66, 69, 140, 173 debridement, 152, 164, 177, 204, 227

irrigation, 35, 46, 47, 49–51, 53, 66, 74, 75, 86, 87, 89, 105, 111, 120, 150, 158, 168, 231, 232, 234, 295, 314

system, 16, 46, 66, 99, 117, 137, 149, 158, 173, 212, 227, 243, 253, 268, 285, 302, 313

treatment, 4, 19, 31, 45, 46, 55, 66, 77, 89, 112, 146, 158, 161, 163, 168, 177, 182, 199, 233, 241, 254, 267, 285–293, 313

S

Self-adjusting file (SAF), 82, 151, 199–217, 290, 292 Smear layer, 46, 71, 100, 144, 152, 163, 173, 208, 228,

255, 292

removal, 75, 103, 111, 112, 144, 152, 166, 181–183, 186, 188–190, 234, 258–260

Sodium hypochlorite (NaOCl), 11, 50, 66, 101, 118, 140, 149, 158, 174, 224, 229, 256, 269, 290, 302, 314

Sonic, 68, 70, 85, 109, 112, 151, 173–191, 200, 204, 233, 292, 295, 308

Syringe irrigation, 45–60, 86, 88, 167

T

Taper, 52, 53, 58, 60, 88, 112, 150, 152, 153, 159–161, 181, 189, 228

Treatment, 4, 19, 45, 66, 99, 118, 139, 149, 157, 177, 199, 222, 230, 238, 253, 267, 285, 301, 313

U

Ultrasonic, 35, 59, 68, 109, 141, 151, 158, 173, 200, 228, 278, 290, 308

V

Vapor lock, 58–59, 70, 82, 133, 150–153, 186, 232

W

Wall shear stress, 47, 50, 56–58, 86, 88, 152, 164