Ann Roy Australas Coll Dent Surg 1998;14:70-4

ENDODONTIC TREATMENT: WHAT CAN AND WHAT CAN'T BESAVED

David Figdor, MDSc, LDS, FRACDS(DipEndo)

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Dr Figdor is in Specialist Endodontic Practice in Melbourne. He is a Senior Fellow, School ofDental Science, University of Melbourne as a part-time lecturer and clinical teacher in endodontics.He is also a visiting scientist in the Department of Microbiology, Monash University, and haslectured widely locally, nationally and internationally. He has authored and co-authored numerouspapers and is the co-author of a chapter in a new textbook on endodontics.

ABSTRACTAlthough endodontic treatment is generally considered

to have a high success rate, not all teeth provide anopportunity for predictable salvage by endodontictherapy and subsequent restoration. New studies areyielding valuable information about factors that affectthe outcome of treatment, which enhances the ability ofthe clinician to make a more accurate preoperativeassessment and improve the quality and predictabilityof treatment.

Most teeth can be saved by endodontic treatment;however, some cases fail despite good treatment. Howcan we assess and predict the outcome of treatment?This paper reviews reasons for biological failure ofendodontic treatment and describes clinical factors thatinfluence whether you might treat, refer, or extract thetooth.

INTRODUCTIONMany clinicians are faced with daily dilemmas about

whether damaged teeth can be salvaged (Fig. 1). The aim ofthis paper is to review success rates, integrate newinformation about the limitations of endodontic treatment,and describe factors to consider in determining whether ageneral practitioner can reasonably treat the case.

It is critical that the essential role of microorganisms inthe development of the periapical lesion be understood.This is because infection is by far the prime cause ofendodontic disease and the outcome of endodontic treatment depends on control of this problem. We know fromanimal and human studies that bacteria are essential for thedevelopment of periapical disease."' Whether or not aninflammatory lesion at the root apex will resolve dependson our ability to remove microorganisms from the rootcanal during endodontic treatment. All of the scientific dataare consistent with empirical clinical experience, whichshows that if you control infection in the canal, periapicalhealing will follow.

Presented at the Fourteenth Convocation. Royal Australasian College ofDental Surueons. Adelaide. October 1998.

Even small numbers of bacteria that persist in the rootcanal at the time of root filling have a significant influenceon the outcome of treatment. In a recent study, theimportance of infection at the time of root filling on theprognosis for treatment was revealed.4 When bacteria couldbe recovered from the canal at the time of root filling, thesuccess rate was 26 per cent lower than for those teeth inwhich no bacteria were recovered at the time of root filling.'This implies that whenever bacteria are present, there isalways a risk that they may survive and continue to inflamethe periapical tissues.

So, the short answer to the question "What can be saved?'is that if you can remove bacteria from the root canalsystem, you have a good change of saving the tooth; butmany clinical cases are more complex than that.

SAVING TEETH - A CONTINUUMI would like to put to you the concept that 'What can and

what can't be saved' is actually a continuum (Fig. 2). Youmight imagine the problem as a walkway with one end onsafe, firm ground and the other end precariously balancedand unsupported. At one end of the walkway, represented bythat on secure ground, certain teeth can be saved with a veryhigh probability of success. At the other end, represented bythe precariously balanced part of the walkway, there aresome teeth that definitely cannot be saved.

The area of most interest and challenge is a grey zone,roughly in the middle. That is where difficult decisionsmust be made about whether or not the tooth can be saved.In a paradoxical way. the more you approach the centre andtry to define where the tooth is in this grey zone, the harderit is to determine or predict the outcome of treatment.

It seems reasonable to assume that the vast majority ofteeth fall into the category represented by the walkway onsecure ground, that is teeth that can be saved. What I shalladdress as we transverse the walkway are two main areas.Firstly, what are the limitations of our success rate from abiological point of view? Secondly, what clinical factorshelp you to determine whether you might treat, refer, orextract the tooth?