37457245 Advanced Endodontics

Advanced Endodontics

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John S Rhodes qualified from Kings College London in 1990, where he was awarded theClaudius Ash prize in conservation and the Jose Souyave endodontic prize. He continued hispostgraduate education at Guys Hospital London, where he achieved a distinction in theEndodontic MSc. He is registered on the GDC specialist list in endodontics and now runs a busyendodontic referral practice in Poole, Dorset.

John S Rhodes lectures widely in the UK and provides numerous postgraduate endodonticcourses. He has published research papers in several refereed journals and is co-author of theendodontic textbook Endodontics: Problem-Solving in Clinical Practice.

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Advanced EndodonticsClinical Retreatment and Surgery

John S Rhodes BDS(LOND) MSC MFGDP(UK) MRD RCS(ED)Specialist in endodonticsThe Endodontic PracticePoole, UK

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2006 Taylor & Francis, an imprint of the Taylor & Francis GroupTaylor & Francis Group is the Academic Division of Informa plc

First published in the United Kingdom in 2006 by Taylor & Francis, an imprint of the Taylor & FrancisGroup, 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN

Tel: 44 (0)20 7017 6000Fax: 44 (0)20 7017 6699E-mail: [email protected]: www.tandf.co.uk/medicine

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Although every effort has been made to ensure that drug doses and other information are presented accu-rately in this publication, the ultimate responsibility rests with the prescribing physician. Neither the pub-lishers nor the authors can be held responsible for errors or for any consequences arising from the use ofinformation contained herein. For detailed prescribing information or instructions on the use of any prod-uct or procedure discussed herein, please consult the prescribing information or instructional materialissued by the manufacturer.

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CONTENTS

Acknowledgements viPreface viiDedication viii

1 Rationale for endodontic retreatment 1

2 Decision making and treatment planning 23

3 Dismantling coronal restorations 45

4 Removal of pastes, gutta percha and hard cements 67

5 Removal of silver points and separated instruments 89

6 Perforation repair and renegotiating the root canal system following dismantling 113

7 Irrigation and medication 129

8 Introduction to surgical endodontics 147

9 Pain control, haemostasis and flap design 163

10 Surgical procedures 177

Index 201

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ACKNOWLEDGEMENTS

I wish to thank the following for kind permission to reproduce figures:Dr CP Sproat: Figure 8:15Dr J Aquilina: Figures 6:18 and 6:19Mr DA Oultram (Optident UK): Figures 7:09, 7:10Mr S Bonsor, Mr G Pearson and Mr J Williams: Figures 7:11, 7:12, 7:13

I would like to acknowledge the contributions of the following people and companies whoprovided equipment for photography: Neil Conduit of QED, Douglas Pitman of DP Medical,David Mason of J&S Davis, Dentsply UK, Henry Schien UK, Optident and Denfotex; the staff atThe Endodontic Practice who agreed to be photographed for illustrative material; my parents, whohelped edit the many drafts; and my wife Sarah and family, who supported me patiently whileI compiled this book.

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PREFACE

This book is intended for the general practitioner with a special interest in endodontics, studentsundergoing specialist training and specialists alike.

Endodontic retreatment poses many practical challenges. Advances in scientific knowledgeand the integration of operating microscopes into endodontic practice have seen the possibilitiesfor predictable endodontic treatment and retreatment expand dramatically.

Advanced Endodontics: Clinical Retreatment and Surgery describes many of the techniques andmethods available for practitioners who wish to undertake the planning and treatment of complexendodontic retreatment.

The pages are copiously illustrated with high-quality photographs and case reports which areused to demonstrate practical non-surgical and surgical techniques. The text is referenced toprovide a comprehensive but discreet source of scientific evidence, principles and further reading.

Knowledge and theory are important in managing complex endodontic retreatment cases, butcannot be a substitute for essential practical and clinical experience. These skills need to belearned and practiced. Novices should always start with the simplest cases and never proceedbeyond their confidence or skill level. Numerous practical courses are available for instruction onretreatment techniques and attendance on them can only be encouraged.

John S Rhodes

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DEDICATION

This book is dedicated to my endodontic mentors:

Professor Tom Pitt Ford

and

Dr Chris Stock

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INTRODUCTION

Patients increasingly expect to retain their nat-ural dentition and are often reluctant to haveteeth extracted. Endodontic retreatment orsurgery may offer the patient a second chanceto save a root-treated tooth that would other-wise be destined for extraction.

The success rate for root canal treatmentcarried out with currently accepted principlesshould be high. Indeed, published figures ofbetween 70 and 95% have been quoted instudies using samples derived from teachinghospitals.1 However, there is marked variationin the ability of operators to achieve successfulresults. Some studies using data collectedfrom general practice have shown relativelylow success rates for root canal treatment. Anassessment into the standard of root canaltreatment in England and Wales for example,showed that 97% of molar root canal treat-ment and 84% of canine and incisor root canaltreatment had technical difficulties,2 whereasin Scotland over 58% of root filled teethshowed signs of periapical radiolucency.3Similar radiographic results have been foundin studies from the USA4 and Holland.5 Theprevalence of endodontically treated teethshowing periradicular radiolucency inScandinavia has consistently been reported tobe between 25 and 35%.6 Obviously, there is acontradiction between what is achievable andwhat is actually achieved. So why does pri-mary endodontic treatment fail?

Endodontic failure comprises: biological failings (infection) cysts root fracture incorrect diagnosis and primary treatment foreign body reactions healing with scar neuropathic problems economic constraints.

BIOLOGICAL FAILINGS

The most common reason for failure ofroot treatment is microbial infection. Micro-organisms and their byproducts have beenisolated from the root canal system and theexternal surface of the root in failed cases. Theymay have persisted following a previousattempt at root canal treatment or gained accessthrough coronal microleakage.

Intraradicular Infection

It is well documented in clinical studies thatteeth with technically deficient root fillings aremore likely to be associated with periapical radi-olucencies. If a root filling is of poor quality, theroot canal system may not have been effectivelydisinfected or could have become reinfectedthrough coronal microleakage (Figures 1.1, 1.2).

The apical portion of the root canal sys-tem can contain bacteria and necrotic tissue

1 RATIONALE FOR ENDODONTICRETREATMENT

CONTENTS Introduction Biological Failings Cysts Cracked Teeth and Fractures Incorrect Diagnosis and Treatment Foreign Body Reactions Healing with Scar Neuropathic Problems Economic Constraints Conclusion References

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substrate even following chemomechan-ical preparation.7,8 If the resultant microbialecosystem is amenable to bacterial survival,a lesion may not heal and root canal treat-ment would be deemed to have failed(Figure 1.3).

The radiographic appearance of a root canalfilling does not give an indication of biologicalstatus and, consequently, a satisfactory radi-ographic result could be failing biologically.9A clinical example would be the misuse of car-rier-based obturating materials where thecanal system may appear to have been wellobturated radiographically, but has not beenadequately instrumented or disinfected.Usually, all that remains in the canal is theradio-opaque plastic carrier. Root canal retreat-ment in this instance should have a goodchance of success as the failure is basicallytechnical and a good aseptic technique has notbeen used (Figures 1.4, 1.5).

Rather more complex and difficult to treatwould be a situation in which an excellentaseptic technique and high standard of skillhas been achieved but the case has failed(Figures 1.6, 1.7).

If the root canal filling fails to provide acomplete seal, seepage of tissue fluidscould theoretically provide a substrate for

ADVANCED ENDODONTICS: CLINICAL RETREATMENT AND SURGERY2

bacterial growth. Studies have reported theoccurrence of viable bacteria in root-treatedteeth with persistent periradicular lesions.10,11To be viable in such conditions, the bacteriahave to survive periods of starvation ornutrient depletion. Bacterial regulatorysystems under the control of determinedgenes are automatically transcripted underadverse conditions. For instance, underconditions of nitrogen starvation, some bac-teria are able to scavenge minute traces ofammonia as a nitrogen source. Facultativebacteria may be able to activate alternativemetabolic pathways and survive in low con-centrations of molecular oxygen by switch-ing from aerobic to anaerobic respiration.Under low concentrations of glucose, somebacteria can activate genes that induceenzyme synthesis to allow the utilizationof various alternative organic carbon sources.

Figure 1.1

This radiograph shows a chronic periapical lesion associ-ated with the maxillary left first premolar. The tooth hasbeen restored with a post and core and is an abutment fora bridge. There is little root filling material present and theroot canal would undoubtedly be infected.

Figure 1.2

In this case the maxillary right first molar has been rootfilled. The root filling material is short in the mesiobuccaland palatal roots but there is little evidence of periapicalpathology. The distobuccal canal has a fractured stainlesssteel instrument in it. The root canal must be infected, asthere is a periapical radiolucency present. The root canalsystem may have become reinfected by coronalmicroleakage following root canal treatment because thefile provided a poor seal. Alternatively, infected materialmay not have been removed or could have been carriedalong the entire length of the root canal prior to theinstrument failing. Sufficient numbers of bacteria are nowpresent to cause persistence of the lesion.

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RATIONALE FOR ENDODONTIC RETREATMENT

The availability of nutrients within the rootcanal system and the ability to survive in amore hostile environment dictate whetherthe remaining microorganisms will die orremain viable.

Bacterial infection is the major cause ofpersistent periapical inflammation followingroot canal treatment. However, there aretechnical failings that may predispose the rootcanal system to inadequate disinfection: poor aseptic technique incorrect irrigant

3

Extraradicular

Lateral canal

Voids between root fillingand canal wall

Apical delta

Dentine of rootwall

Compacted infecteddentine chips

Voids in fillingmaterial

Lateral fins

Figure 1.3

Potential sites of micro-bial infection in thefailed root-filled tooth.

Figure 1.4

A Thermafil root filling has been placed in this mandibu-lar second molar. The filling is short in the distal canal,but the mesial canals look reasonably well obturated. Atell-tale sign on the radiograph that this is not the case isbunching of gutta percha in the access cavity. The obtu-rating material has been stripped off the carrier as it wasinserted. Only the carrier remains in the root canal.

Figure 1.5

The previous case retreated. The distal canal has beenrenegotiated and instrumented. All the canals have beenobturated using gutta percha and sealer.

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inability to prepare the canal to length missed canals procedural errors poor obturation poor restoration and coronal microleakage resistant bacteria.

Poor Aseptic Technique

Surveys carried out amongst general dentalpractitioners show that the majority of rootcanal treatment is carried out without a rubberdam.12,13 Practitioners that do not use a rubberdam concomitantly tend not to use biologi-cally active irrigants. The combined effectcould have a significant bearing on thelikelihood of success, but to date there are no

published data proving that the use of arubber dam increases success rates.

The use of a rubber dam is consideredmandatory for root canal treatment by dentalteachers and endodontic specialists for manygood reasons.

The benefits of using a rubber dam for rootcanal treatment include:

prevention of microbial contamination the safe use of sodium hypochlorite airway protection retraction of the soft tissues unimpeded vision, which is useful with

magnification quicker and more pleasant treatment reduction of microbial aerosol allows the operative field to be dried.


Figure 1.6

The root canal of this maxillary left central incisor wouldappear to have been shaped and disinfected adequately. Alateral canal has subsequently been obturated. The toothwas unfortunately still symptomatic following root canaltreatment and there was tenderness over the apex. Rootcanal retreatment in this instance is going to be complexas the previous attempt is good.

Figure 1.7

Root canal retreatment completed. Following removal ofthe existing root filling material and disinfection, consid-erably more complex anatomy has been cleaned and obtu-rated in the apical region. It was not possible to removeextruded material from beyond the terminus of the lateralcanal.

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Incorrect Irrigants

The modern rationale for root canal treatmentinvolves a chemomechanical approach. Bacteriaare removed mechanically with instruments butalso killed using irrigants which penetrate thecomplex internal anatomy of the root canalsystem (Figures 1.8, 1.9).

The primary irrigant in endodontictreatment should have both proteolytic andbacterial killing properties. In this respect, asolution of at least 1% sodium hypochloritesolution is recommended.14

Irrigants such as chlorhexidine and iodine inpotassium iodide have also been advocated asadjuncts to sodium hypochlorite. Both haveantibacterial properties but do not aid the disso-lution of organic material. Irrigants such as localanaesthetic or saline have no biologically activeproperties and will not aid the dissolution oforganic material or killing of bacteria. Irrigantchoice has a minimal effect on root canal treat-ment outcome when analysed statistically.

Inability to Prepare to Length

Failure to achieve patency during preparationcan result in inadequate penetration ofirrigants. This could result in persistent

infection and endodontic failure. The apical3 mm of a root canal contains the highest per-centage of lateral canals and deltas. There is anargument that if mechanical preparation, andconsequently irrigant penetration, are 23 mmshort of the constriction, the hypotheticallength of canal that has not been disinfectedcould be as great as 67 mm (Figure 1.10).

Outdated filing techniques such as thestepback method15 can be fraught with instru-mentation errors. Zips and elbows are notuncommon, as stiff stainless steel files used ina linear fashion tend to straighten the canals(Figure 1.11).

These in turn are easily blocked withdentine chips that could potentially beinfected. Modern preparation techniques androtary nickeltitanium instruments are usedwith a crown-down approach.16,17 The coronalaspect of the canal is prepared first, allowingmuch better access to the apical part.The development of nickeltitanium fileswith tapers greater than standard handfiles has eliminated the need to step back. Thisspeeds up preparation and reduces thenumber of instruments that are required.These developments have improved the

5

Figure 1.8

This is a cross-section of a root canal that has beenmechanically prepared using nickeltitanium rotaryinstruments. It is quite obvious where material has beenremoved. The areas that are untouched by the files willhave to be cleaned using irrigants and medicaments.

Figure 1.9

Nickeltitanium rotary instruments have been usedto prepare the mesial root canals of a mandibular molar.The majority of the root canal in this instance has beenmachined mechanically and therefore some cleaning willhave occurred during this process. It is not uncommonto find an isthmus joining the two canals in the apicalthird of the mesial root of mandibular molars. Thiswould obviously have to be cleaned using irrigants andmedicaments.

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ability to prepare canal systems predictably,while preventing blockage.

Missed Canals

A missed canal could harbour persistentbacteria. Aberrant or unusual anatomymust therefore be considered in retreatmentcases. If a root-filled tooth appears satisfactoryfrom a radiographic perspective but is still

symptomatic, a missed canal could be sus-pected. Maxillary first molars contain twocanals in the mesiobuccal root in approxi-mately 78% of teeth.18 Mandibular incisorshave two canals in over 40% of cases19 andmandibular first molars frequently containfour canals. The clinician must be aware ofnormal root canal anatomy before re-entering aroot canal-treated tooth and be prepared foradded complexity in retreatment cases(Figures 1.121.14).20


Figure 1.10

Inability to prepare to length.

b

ae

d c

Root filling material23 mm short of constriction (a)

Uninstrumented andpoorly disinfected canal spaceae could be 67 mm

Stiff instrument

Compacted dentine chipscould be harbouring bacteria

File attempts to straightenand transports canal

Zipping

Figure 1.11

File attempts to straighten and transportscanal.

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Procedural Errors

Procedural errors occurring during primaryroot canal treatment of an infected tooth maypredispose the treatment to failure by makingit more difficult to effectively disinfect theentire root canal system.21 Inadequate disin-fection may therefore reduce the prognosis of

initial root treatment and procedural errorsdecrease the chance of successful retreatmentif necessitated.

Ledges are effectively an internal trans-portation of the canal and can be caused by afile working against compacted dentine chips.This infected material may harbour bacteriathat could result in persistent inflammation(Figure 1.15).

Another problem often encountered inretreatment cases is apical transportation.Canals exhibiting apical transportation tend tobe under-filled. There may be voids betweenthe filling material and the canal walls inwhich bacteria could persist. Perforations canresult in endodontic failure when they becomeinfected or allow microleakage.22 In the abovesituations conventional retreatment is nor-mally recommended, as the principal aim is toeliminate bacteria and related irritants fromthe root canal system (Figures 1.161.18).23

Poor Obturation

The aim of obturation and restoration of theendodontically treated tooth is to achieve acomplete seal from the apex to the oral cavity.This prevents the ingress of bacteria by coro-nal leakage or the persistence of bacterialcolonies bathed in nutrients from tissue fluid

7

Figure 1.12

The maxillary left second molar was root treated and thefinal result was reasonable. Careful analysis of theradiograph shows that there is likely to be a secondmesiobuccal canal that has not been prepared. The toothwas still symptomatic.

Figure 1.13

Under microscopic magnification, a view of the pulp floorreveals the position of a second mesiobuccal canal(indicated by a blue arrow).

Figure 1.14

The second mesiobuccal canal is indeed a separate entityand has been shaped, cleaned and obturated.

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in the apical region. Modern obturationtechniques using thermoplasticized gutta per-cha aim to obliterate more of the complex rootcanal system than single cone or silverpoint techniques, which are now consideredobsolete (Figures 1.191.21).

It has been claimed that the success rate ofroot canal treatment is decreased in cases of

over-filling.24 Initially, the toxicity of root canalfilling material was considered to be impor-tant in this respect,25 but most of the materialsused in root canal obturation are eitherbiocompatible or only show cytotoxicity while


Figure 1.16

Apical transportation can occur when the root canal isover-prepared. In this case the palatal root canal of amaxillary molar has been over-prepared with nickeltitanium rotary instruments. Constantly passing theinstrument beyond the apical constriction has resulted instraightening of the terminal part of the root canal and atear adjacent to the gutta percha.

Figure 1.17

There are often many obstacles for the clinician to over-come in order to achieve adequate disinfection of the rootcanal system. In this case the maxillary first molar hasfractured instruments in both mesiobuccal and distobuc-cal canals. The material in the mesiobuccal canal will bemore complicated to retrieve than the distobuccal canal. Itshould be relatively simple to remove compacted guttapercha from the palatal canal.

Figure 1.15

Ledges.

Ledging on outer curveof mesial canals commonlycaused by misuse ofGatesGlidden burs

Infecteddentine chips

Ledge

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The presence of infected dentine or cemen-tum chips in the periradicular lesion has been associated with impaired healing(Figures 1.22, 1.23).29

Poor Coronal Restoration

It would appear that the coronal seal couldhave an important bearing on the success ofroot-filled teeth.30 Having thoroughly cleanedthe root canal system, the coronal restorationhelps to prevent ingress of bacteria into theinternal environment and assists in providinga total seal. Good root canal treatment withgood coronal restoration achieves the best

9

setting.26 Paraformaldehyde-containing mate-rials, however, are considered to be signifi-cantly cytotoxic. It is highly improbable thatmost of the contemporary endodontic materi-als are able to induce inflammation in theabsence of a concomitant endodontic infec-tion. This is probably why a high success ratecan be achieved for root canal treatment inteeth without periapical lesions even in casesof over-filling.27,28 Infection is the most likelycause of failure when root canals are over-filled, and therefore emphasis on the need toprevent and control endodontic infectionefficiently is paramount. Often the apicalseal is inadequate in over-filled root canals.Percolation of tissue fluids could pro-vide nutrients for residual microorganisms to proliferate and reach sufficient numbers toinduce or perpetuate inflammation. Over-instrumentation often precedes over-fillingand in teeth with infected necrotic pulps thiscauses displacement of infected dentine ordebris into the periradicular tissues. In thissituation, microorganisms are physically protected from the host defence mechanismsand can sometimes survive extraradicularly.

Figure 1.18

Root canal retreatment completed. All the separated frag-ments of instrument were successfully removed. Thecanals were located, renegotiated, shaped, cleaned andobturated with gutta percha and sealer. An adhesiveNayyar core has been constructed in amalgam. Themesiobuccal root has two separate canals that join in theapical third.

Figure 1.19

In this case, the root canals of the maxillary secondpremolar and first and second molars have been under-prepared and under-filled. In most canals a single coneobturation technique has been utilized. Despite this, it isinteresting to note that there is virtually no indication ofperiapical pathology. Perhaps the root canal treatmentwas carried out while the teeth were still vital and the rootcanals were not infected. The restorations on these teethare destined for replacement and it is therefore necessaryto carry out root canal retreatment. In this instance,because of the lack of periapical pathology and obvioustechnical failings of the previous treatment, a good prog-nosis should be expected. The distobuccal root of the max-illary left first molar has been resected and an amalgamroot end filling placed. The root tip is still present and justvisible on the radiograph. The root canal will obviouslyneed to be sealed with conventional restorative materialto prevent coronal leakage.

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showed no discernible periapical pathologyin the majority of 39 roots of 32 teeth exposedto caries or the oral environment for over3 months. Indeed, some root fillings had beenwithout restoration for several years.33

The quality of the coronal seal should how-ever be addressed, as leaking restorations andrecurrent caries may compromise the effec-tiveness of cleaning and shaping by allowingmicroleakage.34 It is also important to achievean effective seal with a rubber dam to preventsalivary contamination and reinfection duringroot canal preparation (Figures 1.241.29).

Resistant Bacteria

The microbiological flora in failing root-treatedteeth has been considered to be different fromthat of an untreated canal.35,36 Untreated


outcome, whereas poor root canal treatmentand a poor coronal seal may lead to failure.31,32Root canals that are well prepared and filledmay be able to resist bacterial penetrationeven upon frank and long-standing exposurefor longer than anticipated. A recent study

Figure 1.21

The case has been obturated using a vertically compactedgutta percha technique. The finished preparations are ade-quately tapered and the root canal space well sealed withcompacted gutta percha and sealer.

Figure 1.22

Root canal treatment has been attempted on bothabutments of this three-unit bridge. The mesial abutmentshows fractured instruments in the coronal part of theroot canal, which should be relatively simple to removeduring root canal retreatment. The distal abutment showsa grossly over-extended root filling in the palatal rootcanal with associated periapical radiolucency. The buccalcanals are under-prepared and under-filled. It is likelythat the palatal root canal was over-prepared andthat infected material has been carried through the apexinto the periapical tissues. Root canal retreatment shouldbe perfectly feasible but it is sometimes technically chal-lenging to retrieve over-extended filling materials andthere is always the possibility of persistent extraradicularbacteria.

Figure 1.20

Filling material has been removed from the three teethand a diagnostic working length radiograph shows thecanals have been successfully renegotiated. Patency hasbeen achieved in all of them.

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infected canals usually contain a mixed infec-tion in which Gram-negative anaerobic rodspredominate. Data from culture-based studiesindicate that failed root-treated canals may onlyhave 12 species of generally Gram-positivebacteria. It is worth noting that it is extremelychallenging to successfully culture bacteriataken from canals during root canal retreat-ment. In a study by Sundqvist et al, Enterococcus

11

Figure 1.23

Retreatment of the previous case. The fractured instru-ments were simply removed from the mesial abutmentunder microscopic magnification and the root canalsretreated. In the distal abutment the buccal canals havebeen correctly shaped and now have a tapered form.Over-extended material in the palatal canal has beenretrieved and the palatal canal re-prepared and disinfec-ted. All the canals in the distal abutment have been obtu-rated using a vertically compacted gutta percha techniqueand the case now appears to be adequately sealed.

Figure 1.24

The coronal restoration in this mandibular left first molaris leaking as a result of caries under the distal margin.There is little root filling material in the distal canal and alarge periapical area can be seen around it. The mesialcanals have been obturated using a silver point techniqueand there is also a periapical radiolucency present. Thecoronal restoration is leaking and will need to be removedprior to root canal retreatment.

Figure 1.25

The crown was simply elevated using a Couplands chiseland the core material dismantled. The superficial layerswere removed using a tungsten carbide bur.

Figure 1.26

The remaining material was removed with ultrasonicsand this revealed carious dentine and a very messy pulpfloor. There had been considerable coronal leakage.

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techniques have revealed the presence ofbacteria in the canals of root-filled teeth withperiapical pathology that are rarely revealed inculture studies and have a much greater biodi-versity than previously thought.37

Yeast-like microorganisms have also beenisolated from teeth with failing root fillings38which suggests that they may be therapy-resistant. Candida species have been shown tobe resistant to the most commonly deployedintracanal medicaments in some instances.39Therefore, the microflora associated with fail-ing endodontically treated teeth may beextremely resistant and difficult to eradicateduring retreatment. Alternative intracanalmedicaments and irrigants may be required toenhance the elimination of resistant bacteria inpreviously root-treated canals. Inadequate pri-mary treatment may therefore have a negativeeffect on the prognosis of retreatment.

Extraradicular Infection

It has been suggested that bacterial colonies onthe external root surface may be associated withfailure. Typically, failure occurs in these casesdespite a high standard of primary endodontictreatment. Bacteria such as Actinomyces israeliiand Propionibacterium propionicum have been


faecalis was isolated in 38% of failing canals.Increased proportions of E. faecalis in teeth lack-ing adequate seal during treatment havebeen reported,34 supporting the suggestion thatE. faecalis enters the canal during treatment.Strains of E. faecalis have shown resistance tointracanal medicaments such as calciumhydroxide and may be present as a monoinfec-tion. More recently, DNA-based identification

Figure 1.28

A postoperative radiograph of the tooth showed the rootcanals obturated with a vertically compacted gutta perchatechnique and the coronal substance sealed with an adhe-sive Nayyar core and temporary acrylic crown.

Figure 1.29

Six months postoperatively there was good evidence ofbony healing and the prognosis for successful root canalretreatment looks high.

Figure 1.27

Carious dentine was removed and the root canalsreshaped and disinfected.

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isolated from such infections.4043 Bacterialcolonies arranged in biofilms can evade hostdefences and antimicrobial agents more effec-tively than planktonic cells. A biofilm can bedefined as a microbial population that isattached to an organic or inorganic substrateand surrounded by microbial extracellularproducts forming an intermicrobial matrix.44Bacterial biofilms adjacent to the apical foramenand bacterial colonies located inside periapicalgranulomas have been reported in teeth thathave not responded to root canal treatment.45Extraradicular colonies of bacteria are not erad-icated by conventional disinfection regimes andtherefore, a surgical approach in combinationwith conventional root canal treatment is oftenrequired. It is important to note that when con-sidering retreatment of such a case, conven-tional disinfection of the root canal is usuallyindicated as an initial approach prior to surgery.Periradicular biofilms only occur in a small pro-portion of cases46 and are consequently onlyresponsible for a low percentage of failed cases.The placement of endodontic medicaments intothe periradicular tissues in order to eliminatemicroorganisms and to decompose periradicu-lar biofilms is not to be recommended. This isbecause most are cytotoxic and the antimicro-bial effects can also be neutralized by tissuefluid.

CYSTS

The differential diagnosis of a periapicallesion that is greater than 1 cm in diameterwith well-defined margins will include thepossibility of a radicular cyst.

Radicular cysts are categorized as: apical pocket cysts, in which the epithelial-

lined sac is in communication with the rootcanal system of the tooth (Figures 1.30, 1.31)

apical true cysts, in which the lesion is com-pletely enclosed by the epithelial lining andhas no communication with the root canalsystem of the tooth (Figure 1.32).

As the pocket cyst is in communication with theroot canal, healing should occur in most casesfollowing thorough non-surgical root canaltreatment.47 A true cyst is self-sustaining and

will therefore be unlikely to resolve. In this case,a surgical approach would be required. It isimportant to note that when consideringretreatment of such a case, conventional disin-fection of the root canal is normally indicated asan initial approach prior to surgery.

13

Figure 1.30

Apical pocket cyst.

Epithelial-lined cystic cavity is in communicationwith the root canal system

Figure 1.31

A radicular cyst was located at the apex of this maxillarycentral incisor. It may well have been a pocket cyst, as theroot tip was located within the tissue lining.

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CRACKED TEETH AND FRACTURES

There is a difference between a cracked toothand a vertically fractured tooth. The latterinvolves movement of the two or more frag-ments and radiological signs of bone loss asso-ciated with the root defect. The long-termprognosis for repair of fractured teeth is poorand extraction is usually the only treatmentoption.

Careful assessment of the tooth using anoperating microscope or loupes and an indica-tor dye help the clinician evaluate the degreeof severity before embarking on root canalretreatment.

Treatment will depend on the severity of thecrack. If exposed to the oral cavity, a crack willundoubtedly contain bacteria, which may leadto reinfection of the root-filled canal or inflam-mation alongside the fracture line in the peri-odontal ligament.

Cracks that run across the pulp chamberfloor may have become infected with bacteriaand are therefore more difficult for theclinician to manage. Some teeth will not be

saveable. In others, it may be possible to sealthe pulp floor and place a cusp coveragerestoration to prolong the life of a tooth forseveral years.

Teeth requiring endodontic treatment maybenefit from the placement of a band to preventfracture. Following root canal treatment a fullcoverage crown or cusp coverage restoration isnormally recommended to protect the toothfrom subsequent fracture (Figures 1.331.44).


Figure 1.33

This root-filled tooth has unfortunately failed as a resultof vertical root fracture.

Figure 1.34

Good illumination and magnification are essential inorder to highlight cracks in teeth. This tooth had a micro-crack running down the buccal wall and extending intoone of the mesial root canals. Sometimes cracks can behighlighted by staining.

Figure 1.32

Apical true cyst.

Epithelial lining has no communication with root canal

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INCORRECT DIAGNOSIS ANDTREATMENT

Diagnosis should follow a methodical andlogical progression. Special tests should be

applied to ascertain whether or not a pulp isnecrotic. Haste in attaining a diagnosis canlead to treatment of the wrong tooth(Figures 1.451.47).

FOREIGN BODY REACTIONS

Rarely, failure may occur because of non-microbial factors. Foreign body reactionsagainst cholesterol crystals derived from

15

Figure 1.35

A serious crack running from the mesial to distal of thismandibular molar has unfortunately resulted in verticalroot fracture. The tooth will not be saveable.

Figure 1.36

The maxillary second molar requires root canal retreat-ment. It has been root filled using a silver point technique.Both points are very short of the root apices and themesiobuccal canal has not been prepared, cleaned orobturated.

Figure 1.37

The superficial core material was removed using a dia-mond bur to reveal the heads of the silver points.

Figure 1.38

The remaining core material was then removed withultrasonics, which left the silver points intact so theycould be grasped with Stieglitz forceps and gentlyremoved.

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stable polysaccharide of plant cell walls isneither digested by man nor degraded by thedefence cells. As a result, cellulose can remainin the tissues for long periods and elicit a for-eign body reaction. Fragments of paper pointscan be dislodged or pushed beyond theapex. Leaving a tooth in open drainage is also


disintegrating host cells have been implicatedin failure.48 Extrinsic factors may also be thecause of endodontic failure. Some root fillingmaterials contain insoluble substances, e.g.talc-contaminated gutta percha cones. Thesecan evoke foreign body reactions when pro-truding into the periradicular tissues and causefailure.49 The cellulose component of paperpoints, cotton wool and some vegetablesmay also cause persistent inflammation.50 This

Figure 1.40

After cleaning the pulp floor and removing carious den-tine, a crack was visible. The crack line extended from themesial edge across the pulp floor and down into theorifice of a root canal. This tooth was unfortunately notsaveable.

Figure 1.41

The mandibular first molar pulp has been extirpated, but thetooth still remains symptomatic. Careful analysis of the radi-ograph shows a periapical radiolucency that extends aroundboth roots. This is often an indication of root fracture.

Figure 1.42

The periapical radiolucency highlighted with dots showsthe area tracking around the lateral borders of the root.

Figure 1.39

The silver point root fillings are removed intact.

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ill-advised as the root canal can become packedwith food debris, small particles of whichcan eventually be forced into the periapicaltissues.

Complications arising from such situationsare often very difficult to treat. It is generallynot possible to retrieve such material dur-ing non-surgical root canal retreatment and,therefore, if a tooth is symptomatic followingan orthograde approach, surgery may beindicated.

17

Figure 1.43

Plain orthodontic bands are an excellent means of stabi-lizing a fractured tooth and may prevent its demise dur-ing root canal treatment.

Figure 1.44

The band can be cemented to the tooth during treatment.If the tooth is severely broken down it will make rubberdam placement easier.

Figure 1.45

The maxillary right lateral incisor has an amalgamfilling in the palatal surface and may well have beenroot treated. There is a large palatal swelling thatappears to be located adjacent to the tooth. The centralincisor and canine are not restored. It would appearquite likely that an infected root canal in the lateralincisor has resulted in the formation of an acute abscess.Before embarking on root canal retreatment it is essen-tial to take a good periapical radiograph and carry outsensitivity testing of the adjacent teeth to confirm thediagnosis. Teeth can become non-vital as a result oftrauma. Even though the coronal tooth substance mayappear normal and the teeth do not have any restora-tions in place, the root canal can become infected at alater date via microcracks.

Figure 1.46

Complex root canal retreatment has been completed by anendodontist in the maxillary left first molar but the patientis in pain and is convinced that this tooth is the cause. Hotsensitivity testing reveals that the second molar is irre-versibly pulpitic and requires root canal treatment.

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HEALING WITH SCAR

Healing with scar or fibrous healing is not nor-mally considered failure. It most commonlyoccurs following surgical endodontics, espe-cially when the buccal and lingual plates havebeen perforated by an existing lesion. Theresult is an irregular resolution of the previousradiolucent area.

NEUROPATHIC PROBLEMS

Neuropathic pain is defined by theInternational Association for the Study of Pain(IASP) as pain initiated or caused by a pri-mary lesion or dysfunction in the nervoussystem. Causal factors include injury, infectionand surgery.

Commonly the term atypical facial painhas been used to compartmentalize medicallyunexplained chronic facial pain. Phantomtooth pain (PTP) can occur following dental orsurgical procedures such as root canal treat-ment, root end surgery or exodontias.51 Otherfacial trauma or surgical procedures may havepreceded the onset of PTP, the condition beingcharacterized primarily by persistent pain. Noamount of additional root canal treatment,

root end surgery or exodontia will alleviatethe problem.

Marbach et al reported continued pain formore than 1 month following root canal treat-ment in 7% of individuals. Of this sample,36% showed signs of PTP. Tooth pain prior toroot canal treatment appeared to be a risk fac-tor for PTP.52 The diagnostic criteria for PTPare as follows: the pain is in the face or described as

toothache the pain is described as a constant deep, dull

ache (some patients have a sharp pain thatoverlays the ache)

a brief pain-free period is reported uponwaking and there are no refractory periods

pain develops (or continues) within 1 monthof endodontic treatment, tooth extraction,trauma or medical procedure on the face

there is an area of hyperalgesia overlyingthe area of treatment either on the face orintraorally

sleep is undisturbed no radiographic or laboratory tests suggest

other sources of pain.

A differential diagnosis would include trigem-inal neuralgia, postherpetic neuralgia, acuteherpes zoster and myofascial pain. Althoughthere are no randomized controlled clinicaltrials for PTP, the anticonvulsant gabapentinhas been successful for the treatment of phan-tom limb pain and is probably the drug ofchoice in the treatment of PTP.53 Other drugsinclude tricyclic antidepressants, which mayhave an analgesic effect, nerve block anaesthe-sia and topical drugs such as capsaicin andclonidine.

The clinician should always be wary whenthere are no signs of endodontic pathology buta patient is convinced that a tooth requiresroot canal treatment, especially if multipletreatments have already been completed withno relief of symptoms.

ECONOMIC CONSTRAINTS

Poor remuneration and the time constraintsexperienced by practitioners are often citedas the reason for poor-quality root canal


Figure 1.47

Following simple root canal treatment the patient issymptom-free. Root canal retreatment of the first molarwould have been extremely difficult and would not haveresolved the problem.

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treatment.13 Providing high-quality endodontictreatment is time-consuming. Attempting toachieve the desired goals too fast results in basicbiological treatment aims not being met. This inturn will undoubtedly result in endodonticfailure. Interestingly, the method of remunera-tion does not appear to make a great differenceto the quality of root canal treatment whenmeasured in a global context.

CONCLUSION

The main reasons for failure of primary rootcanal treatment are biological. Therefore, therationale for retreatment has to be based onthe sound biological objectives of eliminationand future exclusion of infection from the rootcanal system.

The importance of careful and skilled tech-nique when completing primary treatment ofteeth with periapical periodontitis, and henceinfected root canals, is highlighted. Iatrogenicproblems causing inadequate cleaning of theroot canal during primary treatment may leadto persistent infection and further difficulty ifretreatment is required.

Adequate disinfection of the root canal sys-tem should allow the balance to tip in favourof periapical healing and success. To achievethis, existing materials, blockages and iatro-genic difficulties will have to be removed andovercome.

REFERENCES

1. Sjrgren U, Hagglund B, Sundqvist G,Wing K. Factors affecting the long-termresults of endodontic treatment. Journal ofEndodontics 1990; 16: 498504.

2. Dummer PM. The quality of root canaltreatment in the general dental services.Journal of the Dental Practice Board Englandand Wales 1998; 19: 810.

3. Saunders WP, Saunders EM, Sadiq J,Cruickshank E. Technical standard of rootcanal treatment in an adult Scottish sub-population. British Dental Journal 1997;182: 382386.

4. Buckley M, Spangberg L. The prevalenceand technical standard of endodontictreatment in an American sub-population.Oral Surgery, Oral Medicine, Oral Pathology1995; 79: 92100.

5. De Cleen M, Schuurs A, Wesselink P,Wu MK. Periapical status and prevalenceof endodontic treatment in an adult Dutchpopulation. International EndodonticJournal 1993; 26: 112119.

6. Eckerbom M, Anderson JE, Magnasson T.Frequency and technical standard ofendodontic treatment in a Swedish popu-lation. Endodontics and Dental Traumatology1987; 3: 245248.

7. Lin LM, Pascon EA, Skribner J, Gaengler P,Langeland K. Clinical, radiographic, andtreatment failures. Oral Surgery, OralMedicine, Oral Pathology, Oral Radiology andEndodontics 1991; 71: 603611.

8. Siqueira JF Jr, Arajo MCP, Filho PFG,Fraga RC, Saboia Dantas CJ. Histologicalevaluation of the effectiveness of fiveinstrumentation techniques for cleaningthe apical third of root canals. Journal ofEndodontics 1997; 23: 499502.

9. Kersten HW, Wesselink PR, Thoden VanVelzen SK. The diagnostic reliability of thebuccal radiograph after root canal filling.International Endodontic Journal 1987; 20:2024.

10. Sundqvist G, Figdor D, Persson S,Sjgren U. Microbiologic analysis of teethwith failed endodontic treatment and theoutcome of conservative re-treatment. OralSurgery, Oral Medicine, Oral Pathology, OralRadiology and Endodontics 1998; 85: 8693.

11. Molander A, Reit C, Dahln G, Kvist T.Microbiological status of root-filled teethwith apical periodontitis. InternationalEndodontic Journal 1998; 31: 17.

12. Marshall K, Page J. The use of rubber damin the UK, a survey. British Dental Journal1990; 169: 286291.

13. Stewardson DA. Endodontic standards ingeneral dental practice A survey inBirmingham, UK, Part 2. European Journalof Prosthodontics and Restorative Dentistry2001; 9: 113116.

14. Bystrom A, Sundqvist G. The antibacter-ial action of sodium hypochlorite andEDTA in 60 cases of endodontic therapy.

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International Endodontic Journal 1985;18: 3540.

15. Mullaney TP. Instrumentation of finelycurved canals. Dental Clinics of NorthAmerica 1979; 23: 575585.

16. Goerig AC, Michelich RJ, Schultz HH.Instrumentation of root canals in molarteeth using the step-down technique.Journal of Endodontics 1982; 8: 550554.

17. Buchanan LS. The standardized-taper rootcanal preparation Part 1 Concepts forvariably tapered shaping instruments.International Endodontic Journal 2000; 33:516529.

18. Al Shalabi RM, Omer OE, Glennon J. Rootcanal anatomy of maxillary first and sec-ond permanent molars. InternationalEndodontic Journal 2000; 33: 405414.

19. Benjamin KA, Dowson J. Incidence of tworoot canals in human mandibular incisorteeth. Oral Surgery, Oral Medicine, OralPathology, Oral Radiology and Endodontics1974; 38: 122126.

20. Pitt Ford TR, Rhodes JS, Pitt Ford HE.Endodontics problem solving in clinicalpractice. London: Martin Dunitz; 2002.

21. Sequeira JF. Aetiology of root canal treat-ment failure: why well-treated teeth canfail. International Endodontic Journal 2001;34: 110.

22. Lee SJ, Monsef M, Torabinejad M. Sealingability of a mineral trioxide aggregate forrepair of lateral root perforations. Journalof Endodontics 1993; 19: 541544.

23. Firas Daoudi M. Microscopic manage-ment of endodontic procedural errors:perforation repair. Dental Update 2001; 28:176180.

24. Strindberg LZ. The dependence of theresults of pulp therapy on certain factors.Acta Odontologica Scandinavica 1956; 14:1175.

25. Muruzbal M, Erasquin J, Devoto FCH. Astudy of periapical overfilling in rootcanal treatment in the molar of rat.Archives of Oral Biology 1966; 11: 373383.

26. Barbosa SV, Araki K, Spangberg LSW.Cytotoxicity of some modified root canalsealers and their leachable components.Oral Surgery, Oral Medicine, Oral Pathology,Oral Radiology and Endodontics 1993; 75:357361.

27. Lin LM, Skribner JE, Gaengler P. Factorsassociated with endodontic treatmentfailures. Journal of Endodontics 1992; 18:625627.

28. Sjgren U, Figdor D, Persson S,Sundqvist G. Influence of infection atthe time of root filling on the outcomeof endodontic treatment of teeth with api-cal periodontitis. International EndodonticJournal 1997; 30: 297306.

29. Yusuf H. The significance of the presenceof foreign material periapically as a causeof failure of root treatment. Oral Surgery,Oral Medicine, Oral Pathology, OralRadiology and Endodontics 1982; 54:566574.

30. Saunders WP, Saunders EM. Coronal leak-age as a cause of failure in root canal ther-apy: a review. Endodontics and DentalTraumatology 1994; 10: 105108.

31. Ray HA, Trope M. Periapical status ofendodontically treated teeth in relation tothe technical quality of the root filling andthe coronal restoration. InternationalEndodontic Journal 1995; 28: 1218.

32. Kirkevang LL, rstavik D, Hrsted-Bindslev P, Wenzel A. Periapical statusand quality of root fillings in a Danishpopulation. International EndodonticJournal 2000; 33: 509511.

33. Ricucci D, Bergenholtz G. Bacterial statusin root-filled teeth exposed to the oralenvironment by loss of restoration andfracture or caries a histobacteriologicalstudy of treated cases. InternationalEndodontic Journal 2003; 36: 787802.

34. Siren EK, Haapsalo MPP, Ranta K.Microbiological findings and clinicaltreatment procedures in endodontic casesselected for microbiological investigation.International Endodontic Journal 1997; 30:9195.

35. Molander A, Reit C, Dahlen G.Microbiological status of root-filled teethwith apical periodontitis. InternationalEndodontic Journal 1998; 31: 17.

36. Sundqvist G, Figdor D, Persson S.Microbiologic analysis of teeth with failedendodontic treatment and the outcome ofconservative re-treatment. Oral Surgery,Oral Medicine, Oral Pathology, OralRadiology and Endodontics 1998; 85: 8693.


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37. Hommez GMG, Verhelst R, Claeys G,Vaneechotte M, De Moor RJG.Investigation of the effect of the coronalrestoration on the composition of the rootcanal microflora in teeth with apical peri-odontitis by means of T-RFLP analysis.International Endodontic Journal 2004; 37:819827.

38. Nair PNR, Sjogren U, Kahnberg KE.Intraradicular bacteria and fungi in root-filled, asymptomatic human teeth withtherapy-resistant periapical lesions: along-term light and electron microscopicfollow-up study. Journal of Endodontics1990; 16: 580588.

39. Waltimo TMT, Orstavik D, Sirn EK,Haapasalo MPP. In vitro susceptibility ofCandida albicans to four disinfectants andtheir combinations. InternationalEndodontic Journal 1999; 32: 4249.

40. Sundqvist G, Reuterving CO. Isolation ofActinomyces israelii from periapical lesion.Journal of Endodontics 1980; 6: 602606.

41. Nair PNR. Periapical actinomycosis.Journal of Endodontics 1984; 12: 567570.

42. Sjgren U, Happonen RP, Kahnberg KE,Sundqvist G. Survival of Arachnia propi-onica in periapical tissue. InternationalEndodontic Journal 1988; 21: 277282.

43. Sakellariou PL. Periapical actinomycosis:report of a case and review of the litera-ture. Endodontics and Dental Traumatology1996; 12: 151154.

44. Costerton JW, Lewandowski Z, Debeer D,Caldwell D, Korber D, James G. Biofilms:the customized microniche. Journal ofBacteriology 1994; 176: 21372147.

45. Tronstad L, Barnett F, Cervone F. Periapicalbacterial plaque in teeth refractory to

endodontic treatment. Endodontics andDental Traumatology 1990; 6: 7377.

46. Siqueira Jf Jr, Lopes HP. Bacteria on theapical root surfaces of untreated teethwith periradicular lesions: a scanningelectron microscopy study. InternationalEndodontic Journal 2001 34: 617627.

47. Nair PNR, Sjgren U, Figdor D, Sundqvist G.Persistent periapical radiolucencies of root-filled human teeth, failed endodontic treat-ments, and periapical scars. Oral Surgery,Oral Medicine, Oral Pathology, Oral Radiologyand Endodontics 1999; 87: 617627.

48. Nair PNR, Sjgren U, Sundqvist G.Cholesterol crystals as an etiological factorin non-resolving chronic inflammation: anexperimental study in guinea pigs. EuropeanJournal of Oral Science 1998; 106: 644650.

49. Nair PNR, Sjgren U, Krey G, Sundqvist G.Therapy-resistant foreign body giant cellgranuloma at the periapex of a root-filledhuman tooth. Journal of Endodontics 1990;16: 589595.

50. Simon JHS, Chimenti RA, Mintz CA.Clinical significance of the pulse granu-loma. Journal of Endodontics 1982; 6:116119.

51. Marbach JJ, Raphael KG. Phantom toothpain: a new look at an old dilemma. PainMedicine 2000; 1: 6877.

52. Marbach JJ, Hulbrock J, Hohn C, Segal AG.Incidence of phantom tooth pain: an atyp-ical facial neuralgia. Oral Surgery, OralMedicine, Oral Pathology 1982; 53: 190193.

53. Rowbotham M, Harden N, Stacey B,Bernstein P, Magnus-Miller L. Gabapentinfor the treatment of postherpetic neural-gia: a randomized controlled trial. JAMA1998; 280: 18371842.

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INTRODUCTION

Although outcomes of endodontic treatmenthave been of interest for many years, thereis an apparent disparity between the successrates reported by cross-sectional studies(3160%) and those of longitudinal studies(8595%). Much of the published data havebeen gleaned from retrospective, non-randomized cohorts. Ideally such studieswould be conducted prospectively and thefactor of interest randomized. For ethical andpractical reasons, this is generally not possi-ble. There are several possible explanations forthe discrepancy in outcomes, such as variationbetween studies in terms of sample size,definition of success, treatment procedures,recall rate, length of observation period andradiographic interpretation. In this respect,the conclusions drawn from original historicaldata may be biased. More recently, meta-analysis and systematic reviews have beenused to assimilate the data provided by multi-ple studies and will hopefully improve thebody of evidence available for clinical use.

WHAT IS SUCCESS?

Patient Viewpoint

A patient may consider success as relief fromacute symptoms, perhaps the resolution ofswelling or absence of tenderness. Patientswill probably be unaware of a chronic lesionthat may, with little warning (and usually at

the most inconvenient time), transform froma dormant state into an acute problem(Figures 2.12.3).

The Clinical Viewpoint

Traditionally, success has been determined bylack of any symptoms and a normal radiologi-cal presentation, while any visible or radiolog-ical signs of disease indicate failure. It was theresearch published by Strindberg in 19561 thatincorporated a system of criteria for assess-ment of success and failure based on the pres-ence or absence of periapical rarefaction

2 DECISION MAKING AND TREATMENT PLANNING

CONTENTS Introduction What is success? Clinical Guidelines of the EuropeanSociety of Endodontics Decision Making Decision Making and Treatment PlanningProcess Decision-making Factors Affecting Outcome Treatment Planning Conclusion References

Figure 2.1

The patient may consider success as relief from acutesymptoms such as gross swelling.

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(Table 2.1). Strindberg considered that thepresence of periapical radiolucency after aperiod of 4 years following root canal treat-ment would indicate signs of biological failure.It is interesting to note however, that completehealing sometimes took up to 10 years.

Clinical evaluation of the patient will deter-mine whether there are any signs of disease,such as swelling, sinus tracts, tenderness onbiting and mobility. The presenting symptomsare also gauged, but as a subjective assess-ment; the absence of symptoms does notnecessarily mean absence of disease. Sinceclinical symptoms tend to occur infrequently,biological evaluation nearly always has to relyon radiographic findings.

Histological Viewpoint

Histological assessment of an endodonticallytreated tooth may offer the ultimate standardfor determining success or failure. But it wouldobviously not be feasible or ethical in the clini-cal environment to take surgical block sectionsof all root-treated teeth for microscopic analysis.


Radiographic findings

Success The contours width and structureof the periodontal margin werenormal

The periodontal contours werewidened mainly around anexisting filling

Uncertain Technically unsatisfactory orambiguous control radiographsthat for some reason could not berepeated

The tooth was extracted prior to3-year follow-up

Failure A decrease in the size of periapicalrarefaction

An unchanged periradicularrarefaction

An appearance of a newrarefaction or increase inprevious rarefaction

Table 2.1 Strindberg criteria for success andfailure

Figure 2.2

In this case the maxillary left first premolar has chronicperiapical periodontitis associated with it. An attemptat root canal treatment has been made but the rootcanals are extremely fine and have not been successfullynegotiated. It is likely that following access cavitypreparation coronal leakage has resulted in completemicrobial colonization of the root canal system. Thepatient is symptom-free. The patient is made aware ofthe risk of acute exacerbation should the tooth not betreated. The prognosis for a non-surgical approachshould be good. Root-end surgery would not beappropriate due to the infected root canals.

Figure 2.3

The completed root canal retreatment. Sclerosed rootcanals can normally be located under high magnifica-tion with a microscope and, once located, carefulpreparation will enable them to be enlarged, irrigatedand then sealed.

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DECISION MAKING AND TREATMENT PLANNING

The question for any clinician is whethera situation that may appear healthy (andsymptom-free) on a macroscopic scale couldshow signs of inflammation and failure at acellular or microscopic level.

CLINICAL GUIDELINES OF THEEUROPEAN SOCIETY OF ENDODONTICS

The European Society of EndodonticsGuidelines indicate that root-filled teeth shouldbe reviewed radiographically at 1 year andthen subsequently as required for up to 4 yearsto assess whether treatment has been success-ful.2 Success would be indicated by relief fromsymptoms, healing of sinus tracts and reductionor complete resolution of periapical radio-lucency. If a root-filled tooth is functional,clinically symptomless and has no evidence ofdisease radiographically, then treatment can beconsidered a success (Table 2.2).

Reit and co-workers systematically studiedthe decision-making process with regard toretreatment. They suggest that patients shouldbe assessed for outcome of treatment 1 yearpostoperatively and, if in doubt, recalled3 years later.3

DECISION MAKING

The decision-making process for endodonticretreatment can be complex. This is perhapshighlighted by the substantial variation thathas been recorded amongst clinicians inthe management of endodontically treatedteeth with symptom-free periapical lesions.4,5Unfortunately, much of the decision-makingprocess appears to lend itself to rather heuris-tic principles, as subjective influences affecttreatment planning decisions. Various aspectsof the endodontic retreatment decision-makingprocess have been explored.6,7 Factors con-tributing to differences in decision-makingprocesses amongst groups of cliniciansinclude the dentist, the patient, cost, environ-mental resources, clinical experience, trainingand speciality.

It has been hypothesized that cliniciansview the disease process as a health scalecontinuum and that variation in instigatingintervention can be considered to result fromindividuals having differing cut-off pointsalong the scale. This was developed as thepraxis concept theory, which proposed thatdentists perceive periapical lesions of varyingsizes as different stages on a continuous healthscale based on their radiographic appearance.8

25

Clinical Radiological

Success There is no tenderness to palpation Contours, width and structure of periodontalor percussion ligament space are normal

Normal mobility and function The periodontal ligament contours areNo sinus tract or periodontal defect widened around excess filling materialNo signs of inflammationNo pain or discomfort

Mixed Sporadic or vague symptoms that are The periapical area has not changed in sizemost often not reproducible The periodontal ligament space does not look

Feeling of pressure or tightness completely normalSlight discomfort when chewing orpressing on tooth with finger or tongue

Failure Persistent symptoms The periapical area has not changed in size or Recurrent sinus tract swelling or pain has enlargedPain on percussion or palpation The appearance of new periapical or lateralMobility or function that is not normal radiolucency

Maximum review time 4 years

Table 2.2 Diagnosis of success and failure

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It has also been suggested that variation intreatment decisions stems essentially from twomain sources, perceptual variation and judge-mental variation.9 Perceptual variation mayaffect the actual process of diagnosis.Judgemental variation relates to the applica-tion of treatment once it has been establishedthat disease is present. The judgement of den-tists is affected by various factors such as theirown individual treatment threshold and theirattitudes to risk, as well as patient andenvironmental factors. It has been postulatedthat guidelines could be compiled for plan-ning root canal retreatment in an attempt toreduce operator variation. Some authors how-ever, consider that variation is not necessarilyundesirable10 and that failure to adhere tostrict guidelines may increase the risk oflitigation. In addition, there is a danger thatdidactic guidelines could stifle innovation andenterprise, which are vital to the continuingdevelopment of the knowledge base.

Ultimately the decision whether to retreat ornot is made between a clinician and thepatient following presentation of all the fac-tors on both sides. Theoretical and practicalknowledge of the clinican as well as the peros-nal and moral values of both parties are alltaken into account. Every situation will beunique and therefore the eventual outcomewill reflect this. Variation in prescriptionwithin normal boundaries and ethical practiceshould perhaps not be perceived as a problem.

If root canal treatment has failed, there areusually five possible treatment options: review or do nothing root canal retreatment root end surgery extraction referral.

Review or do Nothing

There may be occasions where a conservativeapproach is appropriate. The balance of factorsto consider in a case of failed root canal treat-ment, where review is considered, include anassessment of the risk of future disease againstthe risk of leaving untreated disease. One ofthe most difficult decisions is whether toretreat a root-filled tooth that requires a crownwhen it shows no evidence of a defective core

or periapical disease and is symptom-free buthas a technically deficient root canal filling(e.g. inappropriate filling material or the rootfilling is short). It is sometimes very difficult tojudge how much improvement can be gainedby retreatment when difficulties are expectedin carrying out the treatment (e.g. negotiatinga ledge).

The natural history of periapical lesions inroot-filled teeth is not well known andinformation from many studies is inconclu-sive.1,1113 It is difficult to predict the impact ofretreatment in the population as a whole butroot canal infection as a systemic healthhazard is considered to be a low risk for themedically uncompromised individual. As aconsequence, refraining from active treatmentcan be a legitimate treatment modality.14,15 Themajority of treated cases that develop apicalperiodontitis will do so within 1 year.16 Failureafter 1 year is infrequent and therefore obser-vation at this time will, in the majority ofcases, give a good indication of outcome(Figures 2.42.7).


Figure 2.4

The mandibular left first molar has recently been rootfilled. Four root canals were located, shaped, cleaned andobturated. The root filling is of good quality and there areno radiographic signs of periapical pathology. The patientis still experiencing mild symptoms of discomfort on bit-ing. In this case reviewing the situation would be appro-priate as the previous treatment has only just beencompleted. Transient inflammation following initial rootcanal treatment could be causing the patients symptoms.It is probably worth checking that the tooth is not inhyper-occlusion (which is unlikely in this case).

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Review may be considered when: the tooth is symptom-free there is no systemic risk by no intervention there are no signs of inflammation or

infection the tooth does not require a new restoration root canal treatment has only recently been

completed and the outcome is uncertain.

Root Canal Retreatment

Root canal retreatment is often the preferredmeans of treating a failed root canal procedure,especially when the failure is due to a technicaldeficiency.

The existing root filling is removed and theinfected root canal disinfected using irrigantsand medicaments. Root canal retreatment isoften much more complicated than initialtreatment as restorations may need to bedismantled in order to gain access to the canalsystem. It is important to assess whether thetooth is restorable prior to embarking on

prolonged and often expensive treatment. Ifa tooth is unrestorable, then it should beextracted and a suitable replacement provided(Figure 2.8).

The risks encountered during retreatmentmust be considered. These include possibleweakening of the existing tooth substance,damage to existing coronal restoration,difficulties in removing posts or existing rootfillings and the challenge of negotiatingiatrogenic difficulties. These risks arepresented to the patient, included in thedecision-making process and accepted byboth parties before embarking on treatment.An element of personal preference may alsohave an effect on the decision-makingprocess because of factors such as knowledge,experience and even dental school policy(Figure 2.9).

27

Figure 2.5

Although root canal retreatment was carried out on themaxillary right first molar, the maxillary right secondmolar was placed under review. The root filling is grosslyover-extended in the distobuccal canal and a dated silverpoint technique has been used to obturate the canals.There is little radiological evidence of periapical pathol-ogy. The tooth is symptom-free and the coronal restorationis reasonable. A new restoration is not intended as part ofthe overall treatment plan and it would therefore be quiteappropriate to place the tooth under review. Root canalretreatment of such a root filling would be challenging.

Figure 2.6

Root canal treatment of this mandibular left first molarwas completed approximately 6 months previously. Theroot filling is slightly short in all root canals. However, afair attempt has been made to shape the canals and hope-fully disinfect them. A periapical area on the distal roothas decreased slightly in size and the tooth is symptom-free. In this situation, it would be reasonable to review thetooth for a further 6 months. If healing does not appear tobe occurring at 1 year, then root canal retreatment wouldprobably be undertaken. A cusp coverage restorationshould be provided when healing is evident.

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Root canal retreatment is normally indicatedwhen: conventional root canal treatment has failed there are signs of inflammation or infection

associated with a root-filled tooth there are persistent symptoms from a root-

filled tooth, or the presence of a sinus tract,swelling or pain

a root-filled tooth has failed for technicalreasons

there is systemic risk if no intervention ismade

the tooth is restorable the tooth has evidence of periapical radio-

lucency and requires a new restoration the existing root filling is technically deficient

and a new restoration is required the patient conserts to retreatment.

Root End Surgery

A surgical approach is normally reserved forcases in which apparently good-quality root


Figure 2.7

The teeth in the maxillary right quadrant have beenrestored using splinted crowns. The canine and pre-molar teeth have been root filled and post cores cemented.The patient is symptom-free and there are no abnormalclinical signs. Radiographically, the root fillings lookgood but there is a periapical radiolucency associatedwith the second premolar. Non-surgical retreatmentwould be highly complex and risk irreversible damageto the new bridgework. A surgical approach may beappropriate if healing does not occur. As root canaltreatment was only recently completed, this case will bereviewed.

Figure 2.9

Root canal retreatment of these maxillary central incisorsin a young adult should be relatively simple as the singlecone root filings can be easily removed. It is important totry and retain such teeth if an alternative such as animplant solution is to be considered in the long term.

Figure 2.8

The lateral incisor teeth have been root filled and inthe maxillary right lateral incisor an amalgam rootend filling has been placed. Post crown restorationswould have a guarded prognosis as the root length isshort, and the patient is completely edentulous in theposterior segments. It would be appropriate in thiscase to consider alternative treatment options such asan overdenture or perhaps an implant-supportedprosthesis.

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were well cemented in an already weakenedroot, resulting in a high risk of fracture onremoval

root canal treatment or non-surgical retreat-ment has been unsuccessful

as an adjunct to root canal retreatment,perhaps in perforation repair or to removeextruded material

when root or tooth resection is required when a biopsy is required for investigation and exploration, e.g. in

a case of root fracture patient preference, following assessment of

risk.

Extraction

If a tooth is unrestorable or the prognosis forroot canal retreatment is poor, extraction is theonly option. As the prognosis for modern rootcanal retreatment has become clearer, fewerteeth have been placed in this category(Figure 2.12).

29

canal treatment or retreatment has beenunsuccessful. This is because the placement ofa root-end filling in a tooth with an infectedroot canal will undoubtedly lead to failure. Amodern surgical approach is technicallydemanding (Figures 2.10, 2.11).

Root end surgery may be considered when: it is impractical to carry out conventional root

canal retreatment, e.g. if a very large post

Figure 2.10

In some situations root end surgery may be considered incombination with root canal retreatment. In this case alarge radicular cyst was present above the maxillary leftcentral and lateral incisors. Root canal retreatment wascompleted prior to surgery.

Figure 2.11

The radicular cyst was removed surgically.

Figure 2.12

The post that has been cemented in this lateral incisorperforates the root wall. The root canal and perforation siteare infected and there is direct communication with the oralcavity via a periodontal pocket. A better long-term progno-sis may be offered by extracting the tooth and replacing itwith a bridge or implant-supported restoration.

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Extraction may be the treatment of choice: when the tooth or root is fractured and is not

saveable if an alternative, such as removable or fixed

bridgework or an implant-based solution,would offer a better prognosis

when the patient elects not to have retreat-ment when all options have been explained

when root canal retreatment is unlikely to besuccessful.

Referral

There are specialist practitioners who haveadditional expertise in the retreatment ofendodontic failures. Surgical and non-surgicalprocedures are often technically demandingand the results achieved dependent on operatorskill. Complicated cases may be preferentiallyreferred to a specialist or highly experiencedcolleague.

Referral may be appropriate when: the clinician is unable to make a diagnosis access is limited root canal treatment has failed retreatment has failed complexity of treatment is greater than the

clinicians expertise surgical endodontic treatment is required patients present with complex medical

histories combined multidisciplinary problems patient requests referral.

DECISION MAKING AND TREATMENTPLANNING PROCESS

There are several phases that are involved ineventually arriving at a final treatment plan.First, the clinician should complete a thorough,methodical history and examination of thepatient, which includes any necessary radio-graphs and special tests. From the pooled infor-mation, a preliminary diagnosis can be made.The root filling will be confirmed as a success,failure or uncertain diagnosis. The cliniciannow balances the multitude of variables thatcontribute to the assessment of risk. The out-come will be one of the following options: further investigation problem not endodontic

in origin

review non-surgical retreatment root end surgery referral extraction.

Treatment planning can then be undertaken.(History, examination and special tests arecovered in detail in Chapter 1 of Endodontics:problem solving in clinical practice, TR Pitt Ford,JS Rhodes, HE Pitt Ford (eds). London: MartinDunitz; 2003.)

Clinical Assessment

With respect to root canal retreatment, severalfactors regarding previous treatment are ofinterest.

What Treatment Has Been Provided?

Sometimes root canal treatment may havealready been attempted several times. The rootcanals of teeth that have been left open to drainfor a considerable length of time are oftenpacked with food debris and may also becomesaturated with bacterial colonies. These caseswill be difficult to disinfect. Informationdivulged by the patient may highlight likelyproblems that could be incurred duringretreatment. However, patients can becomeconfused or uncertain about specific detailswhen extensive treatment has been carried out,and it is not uncommon in this situation to findthat the patient has forgotten that a particulartooth has even been root filled.

Why Was It Carried Out?

Was the patient in pain? Have the originalpresenting symptoms been improved orchanged as a result of the treatment?

When Was It Completed?

If the root filling has only recently beencompleted, then it may be too early to ascertainwhether it is failing. The timing of originaltreatment may give an indication of thetechniques and materials that have been used.The operator must remember that a singleradiograph gives a snap shot in time anddoes not provide any historical information.


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Who Carried Out the Previous Treatment?

If an experienced practitioner or specialisthas had difficulty gaining access to canals orinstrumenting to length, will furtherattempts improve things? Would it be moreappropriate to consider a surgical approach?(Figures 2.132.15).

Where Was It Carried Out?

The methodology and philosophy of treat-ment vary considerably between differentnations. It is not uncommon to find patientswho have travelled the globe and havereceived treatment in many different countries.Some root filling pastes used in formerEastern Block countries are notoriouslydifficult to remove.

Special Tests

Even though the clinician may suspect a par-ticular root-filled tooth to have failed, it isgood practice to confirm the diagnosis withspecial tests. Sensitivity testing of adjacentteeth and occasionally teeth from the oppos-ing arch may be required to clearly identifythe culprit. Combining the results of specialtests and radiographic reports will help com-pound the evidence. Primary root canal treat-ment is generally much easier to completethan retreatment, and misdiagnosis could beexpensive (Figures 2.162.18).

Radiological Examination

Standardized radiographs taken using a paral-leling device and developed to a high qualityare used to assess the quality of the previousroot filling. In particular they can be used to

31

Figure 2.13

Root canal retreatment of the maxillary left second pre-molar was completed by an endodontist. The tooth wassubsequently restored using a post core and crown. Thereis a small periapical area present and the tooth is occa-sionally symptomatic. The root filling and restoration areexcellent and therefore a surgical approach was consid-ered more appropriate in this case.

Figure 2.14

A view of the resected root end during surgery showing thewell-condensed gutta percha root filling, and a small pieceof separated instrument not visible on the radiograph.

Figure 2.15

The completed root end surgery. The patient is nowsymptom-free.

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check for the correct material and length, andif the material is well condensed. The perio-dontal ligament space can be traced aroundthe root. An increase in width, either laterallyor apically, may indicate the presence of alocalized inflammatory response. There maybe a defined radiolucency in close associationwith the root. The location, size and nature ofany radiolucencies are recorded.

It is sometimes helpful to take radiographsfrom different angles to ascertain whethercanals have been missed. It is also possible toidentify which root canal contains a fracturedinstrument (Figures 2.192.21).

A methodical and meticulous approach tothe assessment of radiographs allows thepractitioner to detect any conditions that arenot consistent with normal, healthy anatomy.In addition, the clinician should always becareful to try to avoid subjective variation.Strict scoring systems such as the periapicalindex (PAI),17 which enable some degree ofstandardization in scientific research, couldperhaps be adapted for use in clinical practicein ensuring quality control and for clinicalaudit (Figure 2.22).


Figure 2.16

In this case a patient presented complaining oftoothache in the maxillary right quadrant that appearedto be originating from the maxillary second premolar.A gutta percha point placed in a buccal sinus tractappeared to be pointing to the root-filled tooth.Sensitivity testing of the adjacent teeth revealed that themaxillary right first premolar was in fact non-vital andthere was evidence of periapical radiolucency aroundthe root tips.

Figure 2.17

A diagnostic root length estimation radiograph revealsthat the palatal root of the maxillary right first premolarextends over the apex of the maxillary right secondpremolar.

Figure 2.18

The case has been completed and, following shaping andcleaning, the sinus tract completely healed. Failure tocarry out sensitivity testing would not have revealed thetrue cause of the patients symptoms and retreatment ofthe maxillary right second premolar would not haveresolved matters.

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Previous radiographs are valuable for pro-viding comparisons and historical information.If a lesion has not decreased in size, root canaltreatment may not necessarily be considered tohave failed. Further review could be required,and this process may continue for up to 4 years.

DECISION-MAKING FACTORSAFFECTING OUTCOME

Periapical Periodontitis

The only factor that has consistently beenproven to influence the outcome of endodontictreatment is the presence of apical periodontitis.It has been shown that the success rate for rootcanal retreatment is approximately 1520%higher in teeth without periapical lesions thanin those with apical periodontitis (Table 2.3).

Following a sound biological approach toroot canal treatment, a success rate of 96% wasachieved for root canal treatment in teeth withno lesion, whereas the presence of apical perio-dontitis resulted in a reduced success rate of86%.21 In the same study, the success rate for

33

Figure 2.19

Taking a radiograph from an angle can help indicatewhether there are missed root canals. In this case theradiograph has been taken from a mesial aspect to showboth root canals in a maxillary premolar. The buccal canalhas been obturated to the full extent. However, the palatalcanal is under-prepared and under-filled.

Figure 2.20

A periapical radiograph of a root-filled maxillary firstpremolar shows excellent root filling.

Figure 2.21

By taking an angled view, the root canals can be separatedand visualized individually. The filling material is short inone canal and there is a fractured instrument tip present.

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root canal retreatment was shown to be 62%.In another study the presence of preoperativeperiapical radiolucency was shown to havea significant negative effect on the outcomeof root canal retreatment, although overallsuccess rates were high (91%).22

One can assume that the presence of aperiapical area normally indicates bacterialinfection of the root canal system. Retreatmentcases often present with apical periodontitisand may be more difficult to disinfect effec-tively both from a technical point of view andas a result of the types of bacteria present.There is no room for missed canals, iatrogenicerrors or complacency if a high success rate is

to be achieved when treating teeth with apicalperiodontitis.

Length of Instrumentation and Obturating Material

Healing was reported in 94% of root-filled teethwhere preparation and root filling ended within02 mm of the radiographic apex.19 Preparationsthat were shorter showed only 68% success.Another study showed that 55% of over-filledroots with defective seals were associated withapical periodontitis, whereas only 12% of root


Little change in bone mineral content. May be functional alteration such as increased mobility

Disorganization of bone texture but not mineral content

Loss of mineral and possiblyshot gun appearance to bone

Classic chronic periapical periodontitis

Similar to PAI 4 but signs of lesion expansion

PAI 1

PAI 2

PAI 3

PAI 4

PAI 5

Figure 2.22

Periapical index (PAI). Adapted with permission from rstavik et al.17

Author Date Apical periodontitis Cases observed Treatment success (%)

Molven and Halse18 1988 None 76 89Molven and Halse18 1989 Present 98 71Sjgren et al19 1990 None 173 98Sjgren et al19 1990 Present 94 62Friedman et al20 1995 None 42 100Friedman et al20 1995 Present 86 56 (uncertain 34;

failed 10)

Table 2.3 Treatment success following endodontic retreatment in teeth with and without apicalperiodontitis

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fillings that ended within 02 mm of theradiographic apex showed periapical radiolu-cency.23 The crux of the problem may bewhether or not an infected canal was presentbefore primary treatment (Figures 2.232.25).

As discussed previously, gutta percha isgenerally well tolerated by the tissues anddoes not initiate an inflammatory responseper se. However, over-filling often occursfollowing over-preparation which, in thepresence of an infected canal, may result inextrusion of infected debris and obturatingmaterial into the tissues. Likewise, under-filling,which may result from failing to instrumentthe canal completely, could result in bacteriaremaining in the root canal following treat-ment. Both situations could subsequently leadto induction or persistence of periapicalinflammati

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