Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2017-06-21, 10:00:36 | version 1.38.0
| opinion root canal disinfection film”, which has a thin but robust layer of mucilage that adheres to a solid surface housing the community of microorganisms. They not only share resources, they also share information that promote each other’s sur- vival through RNA or DNA. As the majority of bacteria will be encapsulated in this layer, purely irrigating without disrupting this layer is inefficient. The word disrupting is a bit kind really—it needs to be destroyed to reveal all its contents and expose it to the bleach for chemical action. It is the methods of disruption of the canal biofilm that has seen a lot of development over the last 10 years or so. Much in the same way a pressure washer can clean that more quickly and efficiently than a sponge, energising the disinfectant results in improved cleanliness. Energising the irrigant This can take many forms. The simple and straight- forward form ensures appropriate exchange of the fluid and displacement into the recesses where air- locks may reside. This can be achieved through apply- ing a GP point into the prepared canal to displace and disperse. Ultrasonic irrigation transmits energy by an oscil- lating instrument. This results in two different phe- nomena. Cavitation is the growth and subsequent col- lapse of small gas bubbles due to a drop in pressure. Acoustic streaming is the bulk movement of fluid when pressure waves are projected, resulting in vortex motion around a fast moving oscillating instrument. This results in shear stresses to tear the biofilm apart. Keeping the canal clean Once irrigated and prepared, the clinician has a choice—to obturate or to dress. Some may argue that the canal is cleanest at the end of instrumentation and that for convenience, obturating in a one visit arrangement is the best option. As we know, not all bacteria are removed or killed during treatment. Dressing the canal with calcium hydroxide may con- tinue the process of eradication of the residual mi- croorganisms over a 2-week period. The choice be- tween the two schemes sometimes boils down to the presenting factors of the case. Where a tooth is diffi- cult to instrument, has a large lesion or is quite obvi- ously chronically infected with a history of pain, then dressing may be more of a consideration. If a tooth is treated in a de novo manner and treatment goals are achieved with no history of pain then a single visit treatment could be utilised. The goal of obturation is to seal the canal system to prevent any reinfection and entomb any bacteria not eradicated by chemomechanical debridement. If the obturation is through the apex, this can have signifi- cant implications. GP through the apex can carry bac- teria outwith of the canal and exacerbate symptoms. A foreign body reaction could also develop. We also have to remember that a beautiful obtu- ration of a canal achieved without rubber dam and utilising saline or local anaesthetic irrigation is sub- standard treatment. It can be difficult to assess the “quality” of treatment when a radiograph of a “failed” tooth is examined in this context. Indeed, an obtu- ration that is short of the radiographic apex having been treated under rubber dam and with copious amounts of irrigation is more likely to be successful than the previous scenario. Attributing too much significance to the radiographic appearance of the obturation is short-sighted. Indeed, Katebzadeh and colleagues in the late ‘90s witnessed healing in the absence of obturation where teeth where in- strumented and irrigated optimally under isolation. Sealants are also antibacterial and aide filling the voids between the GP and the canal system. One further option would be to provide a sub-seal to each of the canal orifices. This can be achieved by removal of 1 mm of GP and packing a good thick mix of IRM packed with a plugger. Covering the cusps The provision of a coronal restoration (if provided optimally) can improve the coronal seal while also structurally protecting the underlying tooth tissue. Due to endodontic treatment, resulting in reduction of tissue bulk and stiffness the risk of fracture in- creases. Where both mesial and distal margins have not been breached and the access cavity is confined to the occlusal surface, a crown restoration may not be required. Once a margin is breached the tooth is more likely to flex and result in cracks or fractures. A commonly asked question, “When should the crown be provided? Soon after the root canal treatment or when the treatment has proven to be successful?” If the success of endodontic treatment is significantly in doubt then this should be communicated to the patient and a well compacted direct restoration may be the best option, otherwise an onlay or if tooth tissue is significantly reduced, a crown should be provided soon after completion. Conclusion Bacteria are public enemy number one in dentistry. Disinfecting the root canal system by irrigating in combination with mechanical instrumentation is key to success in root canal therapy. Preventing further re-infection or persistence of residual bacteria after the formal stages of treatment through dressing initially and a quality coronal seal subsequently is as important as the root canal therapy._ Editorial note: Aws Alani is leading a two-year postgraduate diploma in operative dentistry at King’s College London Dental Institute www.restorativedentistry.org. More information is available online at www.kcl.ac.uk/study/ postgraduate/taught-courses/ operative-dentistry-pgdip.aspx. contact Aws Alani is a Consultant in Restorative Dentistry at Kings College Hospital in London, UK. He can be contacted at awsalani@hotmail.com. www.restorativedentistry.org 16 roots 2 2017