international magazine of oral implantology

I 27implants1_2011 special _ endo-implant algorithm I of endodontic failure.30 Until recently, in vitro testing (dyeleakage,fluidtransport,bacterialpenetration,glu- coseleakage)wasusedtoevaluatethesealingefficacy of endodontic filling materials and techniques by as- sessingthedegreeofpenetration/absorbanceofthese tracers.31–33 Unfortunately, leakage studies are limited static modelsthatdonotsimulatetheconditionsfoundinthe oral cavity (temperature changes, dietary influences, salivary flow). Given the historic dominance of invitro testing,theclinicianmustbecautiousinextrapolating study findings to the clinical situation, regardless of manufacturer’sclaims.34 Thisrelianceoninvalidtesting protocols diminishes the mono-block assertions ap- pliedtothenewgenerationofadhesiveobturatingma- terialsproposedasthereplacementmaterialforgutta- percha.35 Gutta-perchawasintroducedtodentistrybyEdwin Trumanin1847.36 Theconceptofthermo-labilevertical condensationofgutta-perchawasoriginallydescribed by Dr J. R. Blaney in 1927.37 The defining article on ob- turationremainsDrSchilder’sclassiconfillingtheroot- canal space in three dimensions, published 40 years later.38 Logically,onecannotphysicallyfilltherootcanalin two dimensions; however, one can fill the root-canal spacebadlyinthreedimensions.Thisdoesnotdisprove Dr Schilder’s exposition, but it does demonstrate that wordscaneasilybemisconstruedandalterperspective once they become, as Kipling said, “the most powerful drug of mankind”. Ironically, Schilder’s article came sevenyearspriortohistreatiseoncleaningandshaping the root-canal system, which even to this day remains theiconicstandard. TheWashingtonStudybyIngleindicatedthat58% of treatment failures were due to incomplete obtura- tion.39 Thecorollaryisobvious:teeththatarepoorlyob- turated are invariably poorly debrided and disinfected. Procedural errors such as loss of working length, canal/apical transportation, perforations, loss of co- ronalsealandverticalrootfractureshavebeenproven toaffecttheintegrityoftheapicalsealadversely.40,41 TheTorontoStudy that evaluated success and fail- ure of endodontic treatment at four to six years after completionoftreatmentfoundthatteethtreatedwith aflaredcanalpreparationandverticalcondensationof thermo-labile gutta-percha had a higher success rate whencomparedwithstep-backcanalpreparationand lateralcompaction.Highlightingtheverticalcondensa- tion of warm gutta-percha obturation technique as a factorinfluencingsuccessandfailuresimplyconfirmed aperspectiveevidenttomostendodontistsfromyears ofclinicalempiricism. Thereisanever-endingarrayofobturationmateri- als,deliverysystemsandsealersappearinginthemar- ketplace. Each is hallmarked by proprietary modifica- tionsandeachisheraldedasthemostsignificantiter- ation in obturation since the previous one; today, we practice with a sad truism—marketing inexorably di- rects science. However, gutta-percha in combination with a myriad of sealers and solvents remains the pri- mary endodontic obturating material. The dominant systems remain carrier-based obturation (Thermafil, Fig. 11_Numerous researchers have demonstrated that the concept of keeping the apical foramen as small as practical does not mean a size #20 or 25 file. This Schilderian concept should read as small as the apical morphology permits in order to ensure that the free flow of irrigant to the apical terminus enables more definitive cleaning of the apical segment of the root-canal space. Fig. 12_The artist/clinician recognises that negative space surrounding an object is equally important as the object itself. In the case of root-canal therapy, the positive space is alterable but must be created in balance with the encompassing negative space to ensure morphological integrity. Fig. 13_While there is no meta- analysis to elucidate this concern, the incidence of fracture of the mesial root of mandibular molars has been shown to have a significant correlation to cusp fracturing. Fig. 11 Fig. 13 Fig. 12