Australian Dental Journal

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1 Australian Dental Journal The official journal of the Australian Dental Association Australian Dental Journal 2011; 56:(1 Suppl): doi: /j x Current perspectives on post systems: a literature review C Goracci,* M Ferrari* *Department of Dental Materials and Fixed Prosthodontics of Siena, Tuscan School of Dental Medicine, University of Florence and Siena, Italy. ABSTRACT This literature review summarizes the most recent and reliable evidence on post systems. A search was limited to review articles published over the last 10 years in dental journals with an impact factor. Papers cited in the initially retrieved review articles were also included if significant. Preservation of tooth tissue, presence of a ferrule effect, and adhesion are regarded as the most effective conditions for long-term success of post-endodontic restorations. Adhesively luted fibre-reinforced composite post restorations have demonstrated satisfactory survival rates over relatively long follow-up periods. The clinical effectiveness of such restorations has been mainly ascribed to the more biomimetic behaviour of fibre-reinforced composite posts that reduces the risk of vertical root fractures. The most common type of failure when using fibre posts is post debonding and it is generally agreed that achieving stable adhesion to intraradicular dentine is more challenging than to coronal dentine. Several factors related to endodontic treatment, root canal shape, post space preparation, post translucency, adhesive cement handling and curing may have an influence on the outcome of the luting procedure. The most reliable results in fibre post cementation are obtained by etch-and-rinse adhesives in combination with dual-cure resin cements. The use of self-adhesive resin cements has also been proposed. Simplification is an obvious advantage of these new materials. However, the durability of their bond still needs to be verified with long-term clinical studies. Several techniques for pre-treating the fibre-reinforced composite post surface have been tested with the aim of improving the bond strength at the post-core and post-cement interfaces. Silicoating followed by silanization currently appears to be the most effective and convenient method for this purpose. In conclusion, the available evidence validates the use of fibre posts as an alternative to metal posts and preferably to other tooth-coloured posts, such as zirconia dowels, in the restoration of endodontically treated teeth. Longer term clinical trials are expected to further strengthen this evidence. Keywords: Adhesive, cement, fibre-reinforced composite, post, root dentine. Abbreviations and acronyms: FEA = finite element analysis; FRC = fibre-reinforced composite. INTRODUCTION The primary purpose of a post is to retain the coronal restoration in an endodontically treated tooth that has suffered an extensive loss of crown structure. 1 Numerous techniques and materials have been proposed for the restoration of endodontically treated teeth. 2 Metallic prefabricated and cast posts have been utilized for decades. More recently, in response to the request for tooth-coloured posts, several non-metallic dowels have been marketed. Among them, epoxy resin posts reinforced with carbon fibres, epoxy or methacrylate resin posts reinforced with quartz or glass fibres, zirconia posts, and polyethylene fibre-reinforced posts can be distinguished. 3 The objective of this literature review was to summarize the most recent and reliable evidence on post systems. An electronic search of pertinent, English language, peer-reviewed literature was conducted in the MEDLINE database, accessed through PubMed. The following query terms were entered: non-metal post, non metal post, prefabricated post, fiber post, zirconia post, polyethylene fiber post, post-endodontic restoration*, restor* of endodontically treated teeth. The search was limited to review articles published over the last 10 years in dental journals with an impact factor. Papers cited in the initially retrieved review articles were also included if significant. Additionally, the websites of relevant dental journals were explored in the search for in press papers. REVIEW According to the conclusions of a recent review by Dietschi et al., 4 in the restoration of endodontically treated teeth the approach has evolved from a totally empirical level to the current application of biomechanical concepts to guide the decision-making process. ª 2011 Australian Dental Association 77

2 C Goracci and M Ferrari Primarily, preservation of tooth tissue, presence of a ferrule effect, and adhesion are regarded as the most effective conditions for long-term success of the restorative procedure. 1,4 6 Specifically, contemporary adhesively luted fibre-reinforced composite (FRC) post restorations have manifested satisfactory survival rates over relatively long follow-up periods. 4,7,8 The clinical effectiveness of such restorations has been mainly ascribed to the more biomimetic behaviour of FRC posts. 4,9,10 Specifically, in the presence of the less rigid fibre posts, root fractures are very rare, and restorable failures, such as post debonding, are more likely to occur. 4,8,9,11 13 Owing to a greater similarity in elastic properties with dentine, FRC posts allow for a relatively uniform stress distribution to the tooth and the surrounding tissues, thus yielding a protective effect against root fracture. 3,4,8,9 Conversely, titanium, stainless steel and zirconia have elastic moduli (110 GPa, 200 GPa, 300 GPa, respectively) well above that of dentine (18 GPa). In the presence of rigid posts, stress is transmitted internally and concentrates towards the apical level, thus increasing the risk for vertical root fracture, that represents a catastrophic failure. 4,6,9,11,13 A visualization of stress distribution within the restored teeth has been provided by several finite element analysis (FEA) studies. Among them, the analyses using three-dimensional (3-D) models are considered more reliable. Three-dimensional FEA simulations have pointed out the relevance of preserving the ferrule effect, 14 and using restorative materials with elastic properties similar to dentine, such as resin composites, 15 for a more favourable performance of the restored teeth under stress. 4 Conversely, no evidence was found that posts can actually reinforce the roots. 4 These findings are in agreement with the results of static fracture resistance tests, as well as of fatigue studies. 4,16,17 Static fracture resistance tests mimic stresses such as those transmitted in trauma, to abutments of removable dentures, or when removing a temporary crown. However, failures in the oral cavity more commonly occur due to functional loads or parafunctional forces repeated over a long period of time. Such stress conditions are more reliably simulated in fatigue tests. 4 Besides laboratory test outcomes, results from randomized controlled clinical trials, both prospective and retrospective, provide evidence to support the use of FRC posts for the restoration of endodontically treated teeth. 4,7,8,18 In addition to the favourable biomechanical behaviour, other advantageous properties of fibre posts have contributed to their rapid diffusion among clinicians. Fibre posts simplify the post-endodontic restoration procedure in comparison with the use of cast posts, by eliminating the laboratory step. Additionally, fibre posts are relatively easy to remove by boring through the middle of the post with an ultrasonic or a rotary instrument, in case endodontic retreatment is needed. 19,20 Moreover, quartz or glass fibre posts offer the most favourable optical properties for reproducing the natural aspect of the restored tooth. 21 FRC post composition FRC posts are made of carbon, quartz or glass fibres, embedded in a matrix of epoxy or methacrylate resin (Table 1, Fig 1). 3 Fibres are oriented parallel to the post longitudinal axis and their diameter ranges between 6 and 15 lm. Fibre density, i.e. the number of fibres per mm 2 of post cross-sectional surface, varies between 25 and 35, depending on the post type. Therefore, in a tranverse section of the post 30 50% of the area is occupied by fibres. 21 The adhesion between quartz or glass fibres and resin matrix is enhanced by fibre silanization prior to embedding. A strong interfacial bond enables load transfer from the matrix to the fibres and is essential for an effective use of the reinforcement properties. 22 FRC post shape FRC posts are available in different shapes: cylindrical, cylindroconical, conical, double-tapered (Table 1, Fig 2). There are indications in the literature that parallel-sided posts are more retentive than tapered dowels. 1,3 Double-tapered posts better adapt to the shape of the endodontically treated canal, thus limiting the amount of dentine tissue to be removed in post space preparation. 9 Some marketed posts exhibit a coronal head or serrations for retentive purposes (Fig 2). Oval-shaped glass fibre posts were recently introduced for better adaptation into ovoid-shaped canals (Fig 3A and 3B). 23,24 For ovoid-shaped canals, the use of an ultrasonic oval-shaped tip has been suggested for a more conservative post space preparation (Fig 3A). 25 Adhesive luting of fibre posts Several clinical studies have pointed out that the most frequent failure mode of fibre post retained restorations is post debonding. 4,8 Since fibre posts are passively retained into the root canal, the effectiveness of the adhesive cement and the luting procedure plays a relevant role in the overall clinical performance of the restorations. Nevertheless, achieving stable adhesion to intraradicular dentine, particularly at the apical level, remains a clinical challenge, due to the negative influence of several intervening factors. 26 Among them, endodontic irrigants, such as sodium hypochlorite, EDTA, hydrogen peroxide, RC Prep, as well as calcium hydroxide and eugenol of medicaments and sealers 78 ª 2011 Australian Dental Association

3 Post systems Table 1. Chemical composition and shape of several marketed fibre posts Post Fibres Resin matrix Shape RelyX Fiber Post 3M ESPE, St Paul, MN, USA FRC Postec Plus Ivoclar-Vivadent, Schaan, Liechtenstein GC Fiber Post Tokyo, Japan DT Light Post Illusion RTD, Grenoble, France DT Light Post RTD Grenoble, France Macrolock Illusion Post RTD, Grenoble, France Radix Fiber Post Dentsply Maillefer, Ballaigues, Switzerland DT Light Safety Lock VDW, Munich, Germany Dentin Post X Komet, Lemgo, Germany Snowpost Abrasive Technology, Lewis Center, Ohio, USA Reforpost Angelus, Londrina, PR, Brasil FibreKleer Serrated Post Jeneric Pentron, Wallingford, CT, USA Composipost RTD, Grenoble, France Glass Resin Double tapered Glass UDMA, TEGDMA, Ytterbium trifluoride, highly dispersed silicon dioxide Tapered Glass Methacrylate Double tapered Quartz Epoxy Double tapered Quartz Epoxy Double tapered Quartz Epoxy Tapered, circumferential head grooves, spiral head serrations Zirconium enriched glass Epoxy Double tapered Pre-conditioned quartz Epoxy Double tapered Glass Epoxy Tapered with a retentive head Zirconia-rich glass Epoxy Cylindrical with long apical cone Glass Bis-GMA Serrated Glass Bis-GMA, UDMA, HDDMA Serrated Carbon Epoxy Two-stage parallel were found to negatively affect the adhesion of luting agents, by altering dentine structure or interfering with resin polymerization. 4,26 When preparing the post space, part of the dentine possibly altered by canal irrigants, medicaments, and sealers is obviously removed. However, rotary instruments, acting under the far from ideal irrigation possible inside the root canal, produce a thick secondary smear layer, including remnants of plasticized gutta-percha and sealer. Such contaminants hinder chemical interaction and penetration of the luting agent. Therefore, in order to enhance post retention, a careful debridement of the post space walls should be performed prior to cementation. 26 The use of ultrasonic instrumentation in association with EDTA has been suggested for this purpose. 27 As far as the utilization of eugenol-containing root canal sealers is concerned, the clinical indication emerging from several laboratory studies is to refrain from proceeding with post luting immediately after root canal obturation. Residues of unset sealer might indeed be displaced from the apical portion of the canal by (a) (b) Fig 1. (a) Low magnification scanning electron microscope image of the cross-section of a fibre post (x30). (b) A higher magnification of the same section shows diameter and density of reinforcing fibres embedded into the resin matrix (x1550; bar = 10 lm). (From: Ferrari M with Breschi L and Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media 2008, modified.) ª 2011 Australian Dental Association 79

4 C Goracci and M Ferrari (a) (b) (c) Fig 2. Marketed fibre posts exhibit various shapes and may differ largely in translucency. (a) Tapered with retentive coronal head. (b) Double tapered. (c) Serrated. paper points or microbrushes, and be spread over the post space walls, then interfering with cement polymerization. 28 Kurtz et al. verified that the eugenolbased sealer had no significant influence on post retention when adhesive cementation was performed one week after root filling. 29 With regard to luting agents, the current evidence indicates that the most reliable results in fibre post cementation are obtained by etch-and-rinse adhesives in combination with dual-cure resin cements. 4,26 It should, however, be pointed out that the achievement of a valid bond depends on the accuracy of each step in the adhesive handling procedure, that may become quite complex with three-step bonding systems. The limited access to the post space represents an additional complication. In this regard it is worth mentioning that, based on the outcome of bond strength tests and microscopic observations, the use of paper points in post space drying and microbrushes in adhesive application is advisable. 30,31 With the intention to simplify the handling, the use of simplified adhesives has been proposed. However, when utilizing etch-and-rinse two-step and single-step self-etch adhesives, their incompatibility with self-cure and dual-cure cements must be taken into consideration, and the application of a co-initiator of chemical polymerization should be ensured. 32 The same trend toward simplification has led to the introduction of selfadhesive resin cements. These newer systems that do not contain a separate bonding agent have been readily accepted as alternative, easy-to-use materials for fibre post luting. However, self-adhesive cements, that rely on acidic monomers for simultaneous substrate demineralization and infiltration, achieve bond strengths to dentine inferior to those of etch-and-rinse luting agents. Both at coronal and intraradicular level, self-adhesive resin cements demonstrated a limited potential to demineralize and penetrate beyond the smear layer, and established a rather superficial interaction with dentine A clinically relevant issue, still under verification for self-adhesive resin cements, is the durability of their bond to tooth substrates. Bitter et al. reported only an incremental increase in the retentive strength of dowels luted with a self-adhesive resin cement after ageing of post-retained restorations through thermocycling. 36 Conversely, Mazzoni et al. found a significant reduction in retention and an increase in interfacial nanoleakage for posts luted with two self-adhesive cements after thermal cycles. 37 No significant change in retention and seal was observed for the etch-and-rinse luting agent tested as a control. Mazzitelli et al. reported that thermocycling did not affect the post retentive strength of two self-adhesive resin cements, while it increased the bond strength of another luting agent of the same category. 38 To sustain the concern about bond stability is the consideration that if self-adhesive resin cements do not completely shift to neutrality and hydrophobicity with curing, they would remain potentially exposed to hydrolytic degradation phenomena that, with time, could compromise their retentive and sealing ability. In order to clarify these aspects, long-term clinical investigations are desirable. Such evidence is in fact still largely missing, as selfadhesive resin cements have only been recently introduced into the market. 34,35 (a) (b) Fig 3. (a) The ultrasonic tip for post space preparation in ovoid canals and the oval posts indicated for such canals. (b) Scanning electron microscope image of the cross-section of an oval post (x40, bar 500 lm). (From: Ferrari M with Breschi L and Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media 2008, modified.) 80 ª 2011 Australian Dental Association

5 Post systems Concerning the curing mode of the cement, the use of light-cure materials is not advised in post luting, due to the difficulty in getting the light to fully penetrate the post space. 39 It was recently demonstrated that even in the presence of translucent posts (Fig 2), the amount of light reaching the apical third of the dowel space may not be sufficient to effectively cure the cement at that level. 40 In the same investigation it was demonstrated that light transmission was not only prevented in carbon fibre posts, but also significantly reduced in glass fibre posts marketed as being translucent, to the point that resin cement curing would be affected. 40 The disclosed variability in optical properties of the dowels should therefore be taken into due consideration. In such a scenario, dual-cure materials provide the most reliable option for achieving proper cement polymerization all along the dowel space. 4,40 Although purportedly able to polymerize even in the complete absence of light, dual-curing resins develop better mechanical properties if light-irradiated. Therefore, light-curing has been suggested also with dual-cure cements. 41,42 Nevertheless, the auto-cure mode would be advantageous for the purpose of curing stress relief. It should indeed be considered that the C-factor of a thin resin cement film polymerizing within the boundaries of the post space is adverse to stress dissipation. The cement curing stress is also affected by filler load. To gain a deeper insight into the current, market-driven trend toward the use of highly-filled resin composites also suitable for core build-up, a recent research paper assessed contraction stress, post push-out strength and interfacial nanoleakage expressed by experimental resins with different filler loads (10, 30, 50, 70 wt%). 43 The resins with greater filler content exhibited higher contraction stress, lower bond strength and more defective interfaces. Owing to the lower elastic modulus of the less filled resins, their curing resulted in a lower stress to the just established adhesive bond and seal. In consideration of the influence of filler load on resin composites mechanical properties, clinical studies are currently ongoing in order to verify whether lowfilled resins are adequate for the long-term clinical service of post-retained restorations. Zirconia posts High flexural strength, high fracture toughness, chemical stability, biocompatibility and favourable optical properties are advantageous characteristics of zirconia as a restorative material. However, when used for endodontic posts, zirconia has revealed some major limitations. In relation to its rigidity, 3,44 zirconia posts are more prone to cause root fractures than fibre posts. 44 Also, the surface of zirconia posts does not bond to resin composite materials. Even more importantly, the zirconia post falls short of the requirement to be easily removable in case endodontic retreatment is needed. It is in fact practically impossible to grind off a luted zirconia post. 1,3,44 Polyethylene fibres Ultra-high molecular weight polyethylene fibres coated with a dentine bonding agent are used to build-up endodontic posts and cores. 3,45,46 As the fibres adapt to the root canal, canal enlargement is not required according to the manufacturer. 46 The woven fibres have a modulus of elasticity similar to that of dentine, and are claimed to create a dentine-post-core mono-block allowing for a more favourable stress distribution along the root. 46 Only two clinical studies of polyethylene fibre posts are available. In the clinical trial by Turker et al., 46 1 out of 42 dowels debonded over a three-year follow-up period. During the same observation period, 1 out of 87 posts loosened in the prospective study by Ayna et al. 46 It should, however, be considered that in the latter investigation only anterior teeth in patients aged between 8 and 12 years were considered. Adhesion to fibre post surface Research has also been directed at enhancing the adhesion to post surface of the resin composite for cementation or core build-up. 48,49 Particularly in the presence of a post with epoxy resin matrix, the methacrylate-based resin of the cement or the abutment interacts with a highly cross-linked polymer with limited sites available for copolymerization. Chemical reactions are alternatively possible between the resin cement or core material and fibres exposed on the post surface. 31,48,49 Among the various treatments proposed to improve adhesion to the fibre post surface, silanization of quartz and glass fibre posts has been assessed in several laboratory studies, without providing any conclusive evidence. 48,49 While some tests reported a significant increment in cement bond strength following fibre post silanization, according to other investigations the procedure did not contribute any substantial clinical benefit. 31 Silane application would promote adhesion by increasing the post surface wettability, as well as by chemically bridging methacrylate groups of the resin and hydroxyl groups of quartz and glass fibres. Silanization is not effective on resin posts reinforced by carbon fibres that do not present a sufficient number of hydroxyl groups on their surface. 30 Adhesive application after post silanization does not significantly add to the bond strength of a core material to a fibre post with a methacrylate-based matrix. 30 Among the chairside procedures, post surface pre-treatment with 10% hydrogen peroxide for 20 minutes is a simple and effective method to enhance the fibre post-resin composite adhesion. 48,49 By removing a superficial layer of ª 2011 Australian Dental Association 81

6 C Goracci and M Ferrari epoxy resin, hydrogen peroxide exposes to silanization a larger surface area of fibres, without damaging them. Moreover, the spaces thus created between the fibres offer additional sites for micromechanical retention of the resin composite. 48,49 Post-resin composite adhesion is also promoted by tribochemical treatment of the post surface. Such a procedure involves silicoating of the substrate, followed by silanization, and can be performed either in the laboratory (Rocatec system), or at the chairside (Cojet system). 50 Epoxy resin posts industrially pre-treated with silicoating and silanization have also been marketed. Relatively high bond strengths of resin cements were measured on these posts. 50 Silicoating followed by silanization is the surface pre-treatment recommended to increase the bond strength of resin composites to zirconia posts. 3,44 Post radiopacity Fibre post composition has an influence on radiopacity. Glass fibre posts exhibit lower radiodensity than quartz fibre posts which in turn are more radiolucent than carbon fibre posts. The latter posts are anyway less radiopaque than metal or zirconia dowels. 51 Low radiodensity of polyethylene fibres may be a limitation of these reinforcing materials. CONCLUSIONS The available laboratory and clinical evidence validates the utilization of fibre posts as an alternative to metal posts and preferably to other tooth-colored posts, such as zirconia dowels, in post-retained restorations. Preservation of coronal dental tissue, the use of dowels with elastic properties similar to dentine, and effective post adhesion are the most critical factors for the successful clinical performance of restored endodontically treated teeth. While etch-and-rinse adhesives in combination with dual-cure resin cements ensure reliable results in fibre post cementation, the simplification allowed by self-adhesive resin cements is attractive to clinicians. Long-term clinical trials are expected to shed further light on the durability of the bond established by these easy-to-use luting agents. REFERENCES 1. Schwartz RS, Robbins JW. Post placement and restoration of endodontically treated teeth: a literature review. J Endod 2004;30: Theodosopoulou JN, Chochlidakis KM. A systematic review of dowel (post) and core materials. J Prosthodont 2009;18: Baba NZ, Golden G, Goodacre CJ. Nonmetallic prefabricate dowels: a review of compositions, properties, laboratory, and clinical test results. J Prosthodont 2009;18: Dietschi D, Duc O, Krejci I, Sadan A. Biomechanical considerations for the restoration of endodontically treated teeth: a systematic review of the literature. Part II (Evaluation of fatigue behavior, interfaces, and in vivo studies). Quintessence Int 2008;39: Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-core reconstructed teeth: a review. Int J Prosthodont 2001;14: Dietschi D, Duc O, Krejci I, Sadan A. Biomechanical considerations for the restoration of endodontically treated teeth: a systematic review of the literature. Part I. Composition and micro- and macrostructure alterations. Quintessence Int 2007;38: Bolla M, Muller-Bolla M, Borg C, Lupi-Pegurier L, Laplanche O, LeforestierE. Root canalposts for the restorationofroot filled teeth. Cochrane Database of Systematic Reviews 2007, Issue 1: Cagidiaco MC, Goracci C, Garcia-Godoy F, Ferrari M. Clinical studies of fiber posts: a literature review. Int J Prosthodont 2008;21: Cagidiaco MC, Goracci C, Garcia-Godoy F, Ferrari M Clinical trials of fiber posts: a literature review. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Ferrari M. Introduction. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Qualtrough AJ, Mannocci F. Tooth-colored post systems: a review. Oper Dent 2003;28: Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance of endodontically treated teeth restored with composite posts. J Prosthet Dent 2003;89: Fokkinga WA, Kreulen CM, Vallittu PK, Creugers NH. A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems. Int J Prosthodont 2004;17: Salameh Z. Mechanical behavior of endodontically treated teeth restored with fiber posts and full coverage restorations. Siena: University of Siena, PhD thesis. 15. Pierrisnard L, Bohin F, Renault P, Barquins M. Corono-radicular reconstruction of pulpless teeth: a mechanical study using finite element analysis. J Prosthet Dent 2002;88: Lanza A, Aversa R, Rengo S, Apicella D, Apicella A. A 3D FEA of cemented steel, glass and carbon posts in a maxillary incisor. Dent Mater 2005;21: al-hazaimeh N, Gutteridge DL. An in vitro study into the effect of the ferrule preparation on the fracture resistance of crowned teeth incorporating prefabricated post and composite core restorations. Int Endod J 2001;34: Naumann M, Preuss A, Frankenberger R. Reinforcement effect of adhesively luted fiber reinforced composite versus titanium posts. Dent Mater 2007;23: Frazer RQ, Kovarik RE, Chance KB, Mitchell RJ. Removal time of fiber posts versus titanium posts. Am J Dent 2008;21: Gesi A, Magnolfi S, Goracci C, Ferrari M. Comparison of two techniques for removing fiber posts. J Endod 2003;29: Vichi A, Ferrari M, Davidson CL. Influence of ceramic and cement thickness on the masking of various types of opaque posts. J Prosthet Dent 2000;83: Grandini S, Goracci C, Monticelli F, Ferrari M. Fatigue resistance and structural characteristics of fiber posts: threepoint bending test and SEM evaluation. Dent Mater 2005;21: Coniglio I, Garcia-Godoy F, Magni E, Carvalho CA, Ferrari M. Resin cement thickness in oval-shaped canals: oval vs. circular fiber posts in combination with different tips drills for post space preparation. Am J Dent 2009;22: ª 2011 Australian Dental Association

7 Post systems 24. Coniglio I, Magni E, Cantoro A, Goracci C, Ferrari M. Push-out bond strength of circular and oval shaped fiber posts. Clin Oral Investig 2010 Jul 27 [Epub ahead of print]. 25. Coniglio I, Carvalho C, Magni E, Ferrari M. Post space debridement in oval-shaped canals: the use of a new ultrasonic tip with oval section. J Endod 2008;34: Breschi L, Mazzoni A, Ferrari M. Adhesion to intra-radicular dentin. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Coniglio I, Magni E, Goracci C, et al. Post space cleaning using a new nickel titanium endodontic drill combined with different cleaning regimens. J Endod 2008;34: Vano M, Cury AH, Goracci C, et al. The effect of immediate versus delayed cementation on the retention of different types of fiber posts in canals obturated using a eugenol sealer. J Endod 2006;32: Kurtz JS, Perdigão J, Geraldeli S, Hodges JS, Bowles WR. Bond strength of tooth-colored posts. Effect of sealer, dentin, adhesive, and root region. Am J Dent 2003;3:1A 6A. 30. Goracci C, Grandini S, Bossù M, Bertelli E, Ferrari M. Laboratory assessment of the retentive potential of adhesive posts: a review. J Dent 2007;35: Goracci C. Laboratory data and their clinical implications. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, Suh BI, Feng L, Pashley DH, Tay FR. Factors contributing to the incompatibility between simplified-step adhesives and chemicallycured or dual-cured composites. Part III. Effect of acidic resin monomers. J Adhes Dent 2003;5: Monticelli F, Osorio R, Mazzitelli C, Ferrari M, Toledano M. Limited decalcification diffusion of self-adhesive cements into dentin. J Dent Res 2008;87: Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M. Selfadhesive resin cements: a literature review. J Adhes Dent 2008;10: Radovic I, Vulicevic ZR. Self-adhesive cements. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Bitter K, Meyer-Lueckel H, Priehn K, Kanjuparambil JP, Neumann K, Kielbassa AM. Effects of luting agent and thermocycling on bond strengths to root canal dentine. Int Endod J 2006;39: Mazzoni A, Marchesi G, Cadenaro M, et al. Push-out stress for fibre posts luted using different adhesive strategies. Eur J Oral Sci 2009;117: Mazzitelli C, Monticelli C, Toledano M, Ferrari M, Osorio R. Effect of thermocycling on the bond strength of self-adhesive cements to fiber posts. Clin Oral Investig (in press). 39. Wu H, Hayash M, Okamurab K, et al. Effects of light penetration and smear layer removal on adhesion of post cores to root canal dentin by self-etching adhesives. Dent Mater 2009;25: Goracci C, Corciolani G, Vichi A, Ferrari M. Light-transmitting ability of marketed fiber posts. J Dent Res 2008;12: Caughman WF, Chan DCN, Rueggerberg FA. Curing potential of dual-polymerizable resin cements in simulated clinical situations. J Prosthet Dent 2001;85: Kumbuloglu O, Lassila LV, User A, Vallittu PK. A study of the physical and chemical properties of four resin composites luting cements. Int J Prosthodont 2004;17: Ferrari M, Carvalho CA, Goracci C, et al. Influence of luting material filler content on post cementation. J Dent Res 2009;88: Ozkurt Z, Işeri U, Kazazoğlu E. Zirconia ceramic post systems: a literature review and a case report. Dent Mater J 2010;29: Belli S, Eskitaşcioglu G. Biomechanical properties and clinical use of a polyethylene fiber post-core material. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Ayna B, Çelenk S, Atakul F, Uysal E. Three-year clinical evaluation of endodontically treated anterior teeth restored with a polyethylene fibre-reinforced composite. Aust Dent J 2009;54: Turker SB, Alkumru HN, Evren B. Prospective clinical trial of polyethelene fiber ribbon-reinforced, resin composite post-core build-up restorations. Int J Prosthodont 2007;20: Monticelli F, Osorio R, Sadek FT, Radovic I, Toledano M, Ferrari M. Surface treatments for improving bond strength to prefabricated fiber posts: a literature review. Oper Dent 2008;33: Monticelli F, Toledano M, Osorio R. The application of superficial treatment to improve bond strength to fiber posts. In: Ferrari M with Breschi L, Grandini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives. Wendywood: Modern Dentistry Media, 2008: Radovic I, Monticelli F, Cury AH, Bertelli E, Vulicevic ZR, Ferrari M. Coupling of composite resin cements to quartz fiber post: a comparison of industrial and chair-side treatments of the post surface. J Adhes Dent 2008;10: Soares CJ, Mitsui FH, Neto FH, Marchi GM, Martins LR. Radiodensity evaluation of seven root post systems. Am J Dent 2005;18: Address for correspondence: Dr Cecilia Goracci Department of Dental Materials and Fixed Prosthodontics University of Siena Policlinico Le Scotte viale Bracci Siena Italy cecilia.goracci@gmail.com ª 2011 Australian Dental Association 83