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ePaper created 2016-03-31, 16:35:38 | version 1.38.0
| literature review fibre post restorations 24 roots1 2016 Fibre posts and tooth reinforcement: Evidence in the literature Authors: Drs Leendert (Len) Boksman, Gary Glassman, Gildo Coelho Santos Jr. & Manfred Friedman, Canada 'Traditional thinkingthatapostisonlyplacedtore- tainacoreandservesnootherpurposemaynolonger be valid.'1 The preservation of dentine during access open- ing, shaping the canal, preparing the root for place- ment of a post, and during restoration with an onlay or full coverage preparation is critical to the clinical longevity and success of the final restoration.2 It is nowwellrecognisedthatexcessremovalofdentinal support, not only in the root, but also coronally, changes the flexural behaviour and resistance to failure, and that over-flaring the canal for straight line access to the canals weakens the dentinal com- plex.3–6 Dentine coronally must be maintained, not only to give support to the core build-up,7, 8 but also because clinical and invitro studies support the fact that survival of endodontically treated teeth re- stored with posts is directly proportional to the re- sidual coronal dentine that remains.9, 10 Post prepa- ration of the root canal space must not remove additional dentine, as this contributes to a reduced fracture toughness (Fig. 1). Ree et al. state that ‘no additionaldentinshouldberemovedbeyondwhatis necessary to complete the endodontic treatment’.11 If this concept is to be adhered to clinically, then of course the use of parallel sided posts must be elimi- natedfromourclinicalprotocol,asthesepostsusu- ally require removal of sound apical radicular den- tine, creating sharper internal line angles, resulting in a weakened root and a higher root fracture risk (Fig. 2).12 Moreover, the parallel post does not com- plementthetaperedshapeofthepreparedcanal,re- sulting in excess luting composite in the coronal as- pect of the canal, which can decrease bonding efficacyanddecreasedislocationresistance(Fig.3).13 If we adhere to the concept of minimal dentine re- movalintheroot,andifwerecognisethatmostroot canals are ovoid in shape, then a wholly different treatmentapproachthanwhatwehavebeentaught in the past is indicated. Boksman et al. have recom- mended utilising a tapered master quartz fibre post (Macro-Lock Post Illusion X-RO, RTD St. Egreve, France) with additional Fibercones (RTD St. Egreve, France)placedintotheirregularity(lateralspaces)of the canal (Figs. 4 & 5).14 This technique is similar to using a master gutta-percha point with accessory gutta-perchapoints,whichiswell-understood.Util- ising this approach provides several clinical advan- tages,15–19 including more anti-rotational resistance, decreased volume of composite or cement lateral to the post to decrease the C and S Factor constraints (volumetric shrinkage), better adhesion to the root canal walls resulting in decreased microleakage and increasingresistancetodislodgement,aswellasde- creased likelihood for lateral perforation. The com- bination of a post, or multiple posts, that transmit lightefficiently,withsufficientextendedlightcuring Fig.1: Especially in ovoid canals (which are the norm) post preparation can needlessly remove dentine and result in weakening the remaining tooth structure,while leaving lateral gutta percha which compromises bonding/cementation. Fig.1