I recently received the following question from a reader: ‘What’s your opinion on using a cotton pellet with formocresol? We are taking on two-session endodontics, which is what I tend to do generally. . .’
This is a multi-layered question and, while much has been written on the topic in general, the literature is not conclusive on formocresol and one/two visit treatment.
Before intra-canal medicaments become needed, it must be asked why and when would a two-visit treatment plan be preferable to a single visit?
One visit versus two is a clinical controversy and by no means one with a completely clear or simple answer. There are clear indications for one-visit treatments and when cases should be divided into two visits, but there are also examples where it is not entirely clear which is preferable.
In the opinion of the author, clear indications for single-visit treatments are:
1.Vital cases that can be cleaned, shaped and filled adequately to the minor constriction of the apical foramen and in which the apical foramen can be dried easily
2. Necrotic and partially necrotic cases where there is no pre-existing apical percussion, palpation sensitivity and/or swelling. Where the apical foramen can be dried and there has been no apical purulence or drainage of any kind. While this is simple as a single statement, the clinical reality is more complex. Inherent in being able to treat a tooth like this is the assumption that the tooth is enlarged apically to an ideal master apical diameter and that irrigation is copious, correct and the canal path is kept open and patent to the minor constriction.
Additionally, clear indications for two-visit treatments include the following:
1. Any case of complexity where more time is required
2. Where apical percussion sensitivity is present
3. Where palpation sensitivity is present
4. Where swelling is present
5. Where purulence has emerged from the canal, be that purulence frank pus, clear fluid or either mixed with haemorrhage
6. Any case that cannot be dried adequately for any reason.
Judgment calls emerge for one or two visit treatments where:
1. There is an apical lesion (of any appreciable size), the patient is asymptomatic, no apical palpation and percussion sensitivity is present and the tooth is clean and dry after instrumentation. There is literature justification to provide two-visit treatment in these cases because no irrigation or cleaning regimen at this time will sterilise canals predictably and kill all bacteria. It can be argued persuasively that all such cases would be cleaner if they were treated in two visits with a dressing of calcium hydroxide
2. There is literature to prove the contention that re-treatment cases are ideally treated in two visits with an interim dressing of calcium hydroxide but this proof is not absolutely conclusive. To be most conservative, there is no reservation in treating these cases in two visits with an intra-canal dressing of calcium hydroxide.
The anaesthesia challenge
For the general dentist in private practice, or those treating patients in an emergency facility where dental first aid or pain relief is provided, several clinical considerations should be discussed.
For vital teeth that are most often irreversibly inflamed, anaesthesia is usually a challenge. Obtaining this anaesthesia to bring the patient back again is frustrating for the patient and, in the opinion of the author, unnecessary. If the clinician is capable, has time and all the required equipment to finish the tooth, it is far more practical to complete the case. This makes the use of intra-canal medicaments unnecessary for this group of cases, a group that represents the largest number of clinical entities of this type.
The above not withstanding, if the clinician needs to treat such cases in two visits, managing these situations can be made far simpler by observing several simple steps. These include: placing a rubber dam after obtaining anaesthesia, straight-line access and canal location, and if the orifices are negotiable and open, use of an orifice opener such as the K3 shaper files (SybronEndo, Orange, CA, USA).
Remember that the vast majority of the pulp is contained in the chamber and the coronal third of the canals. To obtain access and use the shapers to clear the pulp from the coronal third, and possibly middle third of the canals, one insertion can go far towards predictably and easily removing enough of the inflamed pulp to relieve the patients’ pain.
The insertion of the orifice openers should be gentle, passive, never forced or taken to any arbitrary length and performed crown down, i.e. from larger tapers to smaller. The K3 shapers are available in .12, .10 and .08 tapers. For an average tooth, these would be used in decreasing taper sizes, which is inherently crown down.
Avoiding arbitrary visits
And finally, with regard to vital teeth that fit the description above for one-visit indication, the author believes the clinician should obtain the skills, time, equipment and experience to treat these cases in one visit or not do them. Arbitrarily taking two visits to treat a tooth that could be done in one visit is not profitable for the doctor and, more importantly, unfair to the patient.
For non-vital teeth, especially those with drainage, controversy exists as to whether those teeth should ever be left open to drain or if an intra-canal medicament should be placed. Some would argue that it is malpractice to ever leave a tooth open by intention, while others do it routinely, especially in the presence of purulent drainage. For teeth that are percussion and palpation sensitive with purulent drainage and swelling, the author will leave these teeth open but not for more than two-to-three days to relieve the immediate symptoms.
The author recognises that some clinicians will vehemently disagree with this position. Hopefully, this is a clinical controversy that will be decided definitively in dental literature in years to come. For non-vital teeth without drainage that are going to be treated in two visits, an intra-appointment dressing of calcium hydroxide is certainly indicated.
In summary, the question as to whether intra-canal medicaments are required is really more a discussion on the merits of one-visit treatment. Vital cases can be done in one visit, obviating the need for intra-canal medicaments. Necrotic cases, especially if there is swelling, percussion, palpation sensitivity and purulent drainage, should be handled in multiple visits with consideration given to the strategies outlined in this column. The author welcomes your questions and feedback.