ROEN0210

I 37 feature _ lecture review I roots2_2010 the disconnect that exists between the biological and technical aspects of endodontic training. Themicrobialaetiologyforapicalperiodontitisis well established. Classic work by Kakehashi et al.,1 Sundqvist2 and Moller et al.,3,4 amongst others, demonstrated the causal relationship between the presence of bacteria in the root canal and the de- velopment of apical periodontitis. The continued development of the disease appears dependent on the interaction between the host response and the root-canal microbiota; changes in either will have an effect on its progression. As microbial identifi- cation methods become increasingly sophisticated, it will hopefully be possible to identify more of the bacterial species present in what is a hugely diverse infection.Itisalsoimportanttoexploreandidentify those species associated with disease progression, clinical symptoms, treatment resistance and treat- ment failure. Identification methods that are more complex will be required, as even variations at sub- speciesstrainlevelcancomplicatethesituationand influence the development of apical periodontitis. Whilst identification of the microbiota will give insight into the development of the disease and its associatedsymptoms,thisisonlypartofthepicture. Thebiofilmconceptisnowwellrecognisedinendo- dontics; this means that in addition to identifying species present within an endodontic infection, it is also important to understand the way they may interact and communicate with other, whether the interaction is synergistic or antagonistic, the way nutritional needs are met and the way the biofilm community organises itself for optimum efficiency. Future treatment strategies need to be informed by research conducted into endodontic biofilms; unfortunately much current practice has been developed based on what now appears to be an outdated infection model. So, having discussed where we are with our knowledge of the microbiology and aetio-patho- genesisofapicalperiodontitis,theoriginalquestion still stands. Does a greater understanding of the biology of the disease by those who treat it offer a betterchanceofenhancedoutcomes,andifsohow? Havingestablishedaputativediseaseandmicro- bial model for apical periodontitis, we need to look at our treatment protocols to determine whether they are appropriate for the problems the science has identified. Whilst the technical aspects and dif- ficultiesofroot-canaltreatmentcannotbeignored, they need to be considered in conjunction with the biological imperatives, namely reducing the infec- tionwithintheroot-canalsystemdowntoalevelat which the balance between disease progression and repair is tipped in favour of repair. The highly complex nature of the root-canal system, and the widespread and diverse nature of the infection within it, makes it unlikely that complete disin- fection can take place. A study by Nair et al.5 de- monstrated that even in well-treated teeth biofilm Fig. 2b Figs. 2a & b_When high quality technical work is combined with a biological approach to treatment, healing is likely. A substantial reduction in the size of this lesion, over a nine-month period, occurred as a result of good isolation, thorough chemo-mechanicalcanalpreparation, incorporating active irrigation, and then well-condensed obturation to the apical terminus. Fig. 2a