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ePaper created 2016-05-18, 11:28:18 | version 1.38.0
canal disinfection review | 19 roots 2 2016 Additional disinfection systems In addition to the above-mentioned systems thatwereabletoactivatetheendodonticirrigants and to improve their cleaning capability, end- odontic research is oriented toward the identifi- cation of alternative solutions that could further refine disinfection and assist in the destruction of biofilms and the elimination of micro-organisms. For this purpose, different substances and tech- nologies have been investigated over time with different results. Photoactivated disinfection A new method recently introduced in endo dontics is photoactivated disinfection. This tech- nique is based on the principle that the photo- sensitizing molecules (photosensitizer, PS) have the ability to bind to the membranes of the bac- teria. The PS is activated with a specific wave- length and produces free oxygen, which causes the rupture of the bacterial cell wall on which the PS is associated, determining a bactericidal ac- tion.34 Extensive laboratory studies have shown that the two components do not produce any ef- fect on bacteria or on normal tissue when used independently of each other; it is only the com- bination of PS and light that exert the effect on the bacteria.34 An endodontic system called light-activated disinfection (LAD) has been developed based on a combination of a PS and a special light source. The PS attacks the membranes of micro-organ- isms and binds to their surface, absorbs energy from light and then releases this energy in the form of oxygen, which is transformed into highly reactive forms that effectively destroy micro- organisms. LAD is effective not only against bac- teria,butalsoagainstothermicro-organisms,in- cluding viruses, fungi and protozoa. The PSs have far less affinity for the cells of the body; there- fore, toxicity tests carried out did not report ad- verse effects of this treatment. Clinically, after root canal preparation, the PS is introduced into the canal to working length with an endodontic needle and is left insitu for 60 s to allow the solu- tion to come into contact with the bacteria and spread through any structures, such as biofilms. The specific endodontic tip is then inserted into therootcanaluptothedepththatcanbereached andirradiationisperformedfor30 sineachcanal (Fig. 4). This technique has proven to be effective in laboratory studies at eliminating high concen- trationsofbacteriapresentinartificiallyinfected root canals.35 Care should be taken to ensure maximum penetration of the PS, since it is im- portant that it come into direct contact with the bacteria, otherwise the effect of photosensitivity will not occur. In addition, LAD appears to be ef- fective not only against the bacteria in suspen- sion, but also against biofilm.5 Research is now directed toward evaluating the possibility of in- creasing the antibiofilm effectiveness of LAD, combiningthebenefitsofphotodynamictherapy with those of bioactive glasses and nanoparti- cles, which will be described later. Currently LAD is not considered as an alternative, but rather as a possible supplement to standard protocols of root canal disinfection already in use.5 Laser One of the main disadvantages of the current endodontic irrigants is that their bactericidal effect is limited primarily to the main root canal. Fig.3:Apical negative-pressure irrigation system used to enhance debridement. Fig.3 22016