A week is a long time in endodontics

The question really is: how was I asked to write an article on this subject? Well, I have a tendency to ‘tweet’, both into cyberspace and as my wife would have you know, at home. Most of the time these tweets fall on deaf ears, but this time I was contacted by someone who was listening to me for a change and the idea of this article was born.

What I really meant when I tweeted that, a week is a long time in endodontics, was: precisely that.  A week is often a long time in the career of an endodontist, as well as being a time frame where much can be achieved for our patients clinically.

In one week I had gone from my comfortable existence in London, England one of the greatest cities in the world. Where I had been living for the past 11 years and in which I had recently completed my specialist training. A city where I had been working as a specialist in private practice: with a loyal base of referring dentists.  Then travelled 10500 miles away to Sydney, Australia: in order to start a new life on the other side of the world. The idea of which for many of my colleagues in ‘Blighty’ was as daunting as the journey made by those first boats in the late 1700’s.

There were two things I first noticed when I arrived in Sydney from London: firstly the climate was a great deal warmer than in London, for the time of the year. Apparently I have lived through their coldest night in 61 years. I was quick to remind any New South Welshmen who moaned about the frost that although minus 5 degrees Celsius was cold, just last January we had a number of weeks where the mercury didn’t rise above freezing, even during the day.

The second thing that struck me about Australia was its diverse wildlife. In a week I had been transported from the constant whirr of police sirens outside my flat to being woken every morning by the squawk of a cockatoo. But aside from the benign differences Australia has a dangerous natural wild life. In fact they have 11 out of the 15 most venomous snakes in the world here, all of which can be found at a neighbourhood near you.  According to a local I spoke to one morning, if you are unlucky enough to be bitten by a Death Adder,” you only have enough time to fill in the paper work!” I have also been assured by a few friends that if you go to leafy suburbs in Sydney at some stage you will encounter the Sydney funnel web spider, the most dangerous spider in the world. Thankfully whilst the wildlife can be unpleasant, the locals were nothing but friendly and welcoming.

There are approximately 30-40 endodontists in New South Wales making it a very close knit community, compared to the one I was used to in London. As one endodontist put it, “we all get along quite well, over here.” In fact the stereotype of the outspoken Aussie gloating about their latest sporting achievement certainly does not apply in Sydney, or at least amongst the endodontic specialists.

The small number of endodontists in Sydney means that if you are lucky enough to have established a solid referral base it is a city where the sky is the limit. But if you are beginning your career it can take time. Most of the recently qualified specialists are eager to move as far away from the CBD as possible in a bid to attract referrals from local dentists, whose patients are sick and tired of taking the time consuming and expensive trip to the CBD. Sydney has some of the highest charges for parking in the world and much like London if a local wants to travel to the centre of town they avoid taking the car. Sydney recently ranked as the 15th most expensive city in the world and 10 years ago it didn’t even make the top 100. Testament to how things have changed over here in such short time.

As I previously stated in a week we can do a lot to help our patients suffering from endodontic disease. A patient can present at our surgery after not having slept for days, due to an acute episode of apical periodontitis and just a week later after our ‘magic’ treatment become totally free from pain. Similarly a chronic sinus tract can heal completely just one week after our endodontic treatment. We know it is the removal of the bacteria which halts the disease process, but there is a vast network of webs, fins and lateral canals within the root which harbours bacteria. This complex anatomy makes total sterilisation of the root canal system impossible. So why do we often get such quick resolution of endodontic disease if we don’t remove all the microorganisms? There are two answers to this question.

Firstly, the human body has a great capacity to heal. It has evolved over millions of years to recover in even the most adverse conditions. In endodontic disease this innate ability is made more likely when bacteria are absent from the root canal or when they are only present in low numbers. So it is likely that the patient’s ability to heal is an important factor in the success of endodontic treatment. However, unlike in periodontics there is little evidence relating the success of endodontic treatment to the patient’s general well being. 

The second part of the answer is that our use of antimicrobial irrigants and medicaments kill bacteria as well as change the environment inside the root canal. This makes bacterial survival more difficult, which in turn disrupts the disease process. It is this lowering of the bacterial count that then allows the body to heal. In a similar way that oral hygiene prevents periodontal disease and caries, even though the oral cavity is not sterilised.

Despite the fact we have the complex anatomy of the root canal system against us, we have a number of factors on our side. Importantly the survival of most bacteria relies on synergistic interactions with other species to obtain nutrients and to create an environment with the optimum PH and oxygen tension. These interactions between species are a critical factor in allowing bacteria to be able to establish themselves in the right environment, as well as in enough numbers to cause apical periodontitis. There are very few bacteria in the oral cavity that can cause endodontic disease without the need for other species.

When we open the root canal of a tooth we instantly change the oxygen tension and this will inevitably affect the community of bacteria inside. The scraping of the canal walls using endodontic files breaks up the bacterial biofilm (plaque) attached. This has two purposes, the first being the physical removal of bacteria from within the root canal and the second being the dispersion of the bacteria from the biofilm. By doing so we are removing the protective layer of the biofilm. The use of antimicrobial irrigants onto these ‘unprotected’ bacteria then causes lysis of the bacterial cell. Using irrigants to remove the smear layer allows the antibacterial irrigants to penetrate the dentinal tubules and the inaccessible lateral canals, which we cannot clean directly. When we dress the root canal with calcium hydroxide for a week it works in two ways. The calcium hydroxide breaks into calcium and hydroxyl ions and the hydroxyl free radical causes lysis of the bacterial cell directly and also raises the PH inside the root canal. This increase in the environmental PH prevents the bacterial enzymes from working and denatures the bacterial cells DNA.

At the end of the appointment the provision of a new restoration to replace the previously defective one, prevents salivary products and oxygen from reaching the bacteria and therefore cuts off their energy (food) supply. These changes in the environment then allow the body to heal which is something it does most effectively.

In endodontic surgery the idea is similar. By removing the root apex we are assuming that most of the bacteria are present in this region. Again this will remove a great number of bacteria as well as the complex anatomy which was difficult to disinfect previously. Placement of a retrograde restoration then prevents bacterial toxins escaping or inflammatory proteins from the periapical tissues reaching any bacteria still present within the root canal system.

A former undergraduate tutor of mine used to say,”When treatment is not going to plan Periodontists will always blame the patient, but Endodontists will always blame themselves. So if you find yourself in this situation just remember, a week is a long time in endodontics.