Nonmetallic Prefabricated Dowels: A Review of Compositions, Properties, Laboratory, and Clinical Test Results Nadim Z. Baba, DMD, MSD,1 Gary Golden, DDS,2 & Charles J. Goodacre, DDS, MSD3 1 2 3 Associate Professor, Department of Restorative Dentistry, Loma Linda University, School of Dentistry, Loma Linda, CA Assistant Professor, Department of Restorative Dentistry, Loma Linda University, School of Dentistry, Loma Linda, CA Professor and Dean, Department of Restorative Dentistry, Loma Linda University, School of Dentistry, Loma Linda, CA Keywords Nonmetallic prefabricated dowels; nonmetallic prefabricated posts; restoration of endodontically treated teeth; composition; properties; laboratory results; clinical results. Correspondence Nadim Z. Baba, Loma Linda University, School of Dentistry, Department of Restorative Dentistry, 11092 Anderson St., Loma Linda, CA 92350. E-mail: nbaba@llu.edu Accepted July 16, 2008 doi: 10.1111/j.1532-849X.2009.00464.x Abstract Purpose: Prefabricated dowels have become popular, and a wide variety of systems are available. Recently, in response to a need for tooth-colored dowels, several nonmetallic dowels such as carbon-fiber epoxy resin, zirconia, glass fiber-reinforced epoxy resin, and ultra-high polyethelene fiber-reinforced dowels are available. With a plethora of different materials and systems currently available for use, an overview of the scientific literature on nonmetallic dowels is indicated. This article reviews the current literature dealing with the compositions, properties, and laboratory and clinical test results of nonmetallic prefabricated dowels. Methods: A comprehensive review of the literature was completed seeking evidence for the treatment of teeth with nonmetallic prefabricated dowels. A search of English language peer-reviewed literature was undertaken using MEDLINE and PubMed with a focus on clinical research articles published between 1996 and 2007. A hand search of relevant dental journals was also completed. Results: The literature demonstrates that in vitro investigations demonstrated favorable physical and mechanical properties of these dowels; however, clinically, there has been a wide range of reported failure percentages. Conclusion: Since there is considerable variation in reported failure percentages, longer-term studies are needed that present data regarding all types of complications that have been identified in the literature. Using a dowel to restore a tooth whose natural crown is missing is not a recent dental treatment. In the Tokugawa era (1603 to 1867), the Japanese used wooden dental restorations designed to function like the modern dowel crown.1 Pierre Fauchard in his book, The Surgeon-Dentist, or, Treatise on the Teeth, published in 1728, described a technique by which a silver post was used to retain a natural tooth crown or an ivory crown to a root.2 In 1876, The Richmond Porcelain and Gold Collar Crown was introduced and was modified through the years to become a one-piece dowel and crown.3,4 Root fractures and other difficulties encountered with these early treatments led to the development of cast dowels that continue to be used today. Although modern endodontic, prosthodontic, and periodontal therapies have allowed patients to retain severely compromised teeth for longer periods of time, the restoration of these teeth remains a challenge. Despite a number of innovations and decades of research on dowels, failures still can occur when endodontically treated teeth are restored. Studies indicate that the most common dowel complications are post loosening and root fracture;5-12 however, the overall clinical failure rate of dowels remains relatively low. Combined data from eight studies indicated that dowels had an average absolute rate of failure of 9% (7% to 14% range).7-11,13-17 Prefabricated dowels have become popular, and a wide variety of systems are available. Recently, in response to a need for tooth-colored dowels, several nonmetallic dowels such as carbon-fiber epoxy resin, zirconia, glass fiber-reinforced epoxy resin, and ultra-high polyethelene fiber-reinforced dowels have become available. The purpose of this article is to provide a synopsis of the available literature regarding these new nonmetallic prefabricated dowels, including their compositions, properties, laboratory test results, and clinical outcomes. Methods A comprehensive review of the literature was completed seeking evidence for the treatment of teeth with nonmetallic c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  527 Baba et al Nonmetallic Prefabricated Dowels prefabricated dowels. A search of English language peerreviewed literature was undertaken using MEDLINE and PubMed with a focus on clinical research articles published between 1996 and 2007. A hand search of relevant dental journals was also completed. Keywords included the following: carbon fiber-reinforced epoxy resin dowels, carbon fiber-reinforced epoxy resin posts, glass fiber-reinforced epoxy resin dowels, glass fiber-reinforced epoxy resin posts, polyethylene fiberreinforced dowels, polyethylene fiber-reinforced posts, zirconia dowels, zirconia posts, along with combinations of the term composition, physical properties, mechanical properties, laboratory studies, and clinical studies. Available abstracts were reviewed, and full-text articles of selected abstracts obtained online or via the interlibrary loan program at Loma Linda University Library. Results Carbon fiber-reinforced epoxy resin dowels Composition and properties The carbon fiber-reinforced epoxy resin dowel system (CF) was developed in France in 1988 by Duret and Renaud18-20 and first introduced in Europe in the early 1990s.21-23 The matrix for this dowel is an epoxy resin reinforced with unidirectional carbon fibers parallel to the long axis of the dowel. The fibers are 8 µm in diameter, and uniformly embedded in the epoxy resin matrix. By weight, the fibers comprise 64% of the dowel and are stretched before injection of the resin matrix to maximize the physical properties of the dowel.18,24,25 The dowel is reported to absorb applied stresses and distribute these stresses along the entire channel.26 The bulk of the carbon fiber is made from polyacrylonitrile by heating it in air at 200◦ C to 250◦ C and then in an inert atmosphere at 1200◦ C. This process removes hydrogen, nitrogen, and oxygen, leaving a chain of carbon atoms and forming carbon fibers.27 The carbon fiber-reinforced dowel has been reported to exhibit high fatigue strength, high tensile strength, and a modulus of elasticity similar to dentin.21,24,28-30 The dowel was originally radiolucent; however, a radiopaque dowel is now available. Radiopacity is produced by placing traces of barium sulfate and/or silicate inside the post. Mannocci et al31 radiographically examined five types of fiber dowels. They found that only two of the five dowels had uniform radiopacity. Finger et al32 examined the radiopacity of seven fiberreinforced resin dowels and found CF posts had an acceptable radiopacity. The dowel is also available in different shapes: double cylindrical with conical stabilization floors or conical shapes (Fig 1). The surface texture of the dowel may be smooth or serrated. Studies have indicated that serrations increase mechanical retention although the smooth-sided dowel also bonds well to adhesive dental resin.30,33 The surface of the dowel has a roughness of 5 to10 µm to enhance mechanical adhesion of autopolymerizing luting materials, and the dowel appears to be biocompatible based on cytotoxicity tests.29,34 528 Figure 1 Carbon fiber-reinforced epoxy resin dowels. Laboratory test results Physical property tests of CF dowels have produced contrasting results; some studies found them to be stronger than metal dowels,25,28 whereas other studies determined their strength was comparable25,28 or inferior35-37 to metal dowels. The fracture resistance of extracted teeth restored with CF dowels has been extensively evaluated. Several studies28,35,37,38-41 indicate CF dowels are less likely to cause root fracture than metal dowels; however, two studies42,43 found no significant difference in tooth fracture resistance, and one study38 reported a significantly higher fracture threshold for cast metal dowels. Multiple studies42,44-47 determined there was a decrease in the strength properties of CF dowels after thermal cycling and cyclic loading. Additionally, contact of CF dowels with oral fluids reduced their flexural strength values.34,46,47 A proposed advantage of fractured CF dowels is their purported ease of removal.37,48-52 A removal kit has been suggested48-51 for dowel removal with a recommendation that it be a single-use item.49 Clinical outcomes Twelve studies have clinically evaluated CF dowels with a wide range of failure percentage being reported (Table 1). Failure rates have ranged from zero after a mean postplacement c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  Baba et al Nonmetallic Prefabricated Dowels Table 1 Clinical studies for carbon fiber-reinforced epoxy resin dowels (CF) Lead author Study length Dowels placed CF dowels placed % of clinical failure 173 236 200 1304 173 236 100 1055 1.73% 0% 5% 2.8% Wennström J, 1996 Fredriksson M, 1998 Ferrari M, 200057 Ferrari M, 200056 3 to 4 yrs 2 to 3 yrs (mean 2.7) 1 to 4 yrs (mean 3.8) 1 to 6 yrs (mean 3.8) Glazer B, 2000 6 months to 4 yrs (mean 2.3) 59 59 7.7% Mannocci F, 2002 King PA, 2003 Hedlund SO, 2003 Tidehag P, 2004 Mannocci F, 2005 Segerstrom S, 2006 1 to 3 yrs 1 to 8 yrs (mean 7.3) 1 to 4.9 yrs (mean 2.3) 5 to 9 yrs (mean 7.2) 1 to 5 yrs 1 month to 10 yrs (mean 6.7) 117 27 65 642 219 99 117 16 65 642 110 99 6.5% 28.5% 3% 10% 10% 35% Ferrari M, 2007 7 to 11 yrs 985 775 7.2% time of 2.7 years53 to a high of 35% after a mean postplacement time of 6.7 years.54 Other reported failure rates were: 1.73% after 3 to 4 years,22 3% after a mean time of 2.3 years,55 2.8% after a mean time of 3.8 years,56 5% after a mean time of 3.8 years,57 7.2% after 7 to 11 years,58 7.7% after a mean time of 2.3 years,59 10% after a mean time of 7.2 years,60 10% after 1 to 5 years,61 6.5% after 1 to 3 years,62 and 28.5% after a mean time of 7.3 years.63 The types of failures have been dowel loosening, periapical pathology, root fracture, crown debonding, secondary caries, periodontitis, dowel fracture, tooth extraction for unspecified reasons, and unknown reasons for failures. Dowel loosening was reported in seven of the 12 studies,55,56,59,60,62,63 whereas there was no reported loosening in five studies.22,53,57,58,61 Of the studies that reported dowel loosening, only five54,55,59,62,63 quantified the number of dowels that loosened. In these five studies, the following dowel loosening data were provided: 1 of 59 dowels loosened,59 2 of 65 dowels loosened,59 3 of 99 dowels loosened,54 4 of 27 dowels loosened,63 and 3 of 117 dowels loosened.62 Periapical pathology was reported in five54,55,57-59 of the 12 studies with 2 of 100,35 2 of 59,59 10 of 99,54 and 10 of 77558 failures occurring via this means. One study56 indicated periapical pathology was encountered, but the number of failures produced from this source was not identified. Root fracture occurred in three of the studies22,54,58 where 2 of 173,22 14 of 99,54 and 14 of 77558 roots fractured. Crown debonding was reported in three studies,58-60 and dowel fracture was reported in one study.22 Glass fiber-reinforced epoxy resin dowels Composition and properties The glass fiber-reinforced epoxy resin dowel (GF) is made of glass or silica fibers (white or translucent). Glass fiber dow- Types of failure 2 root fractures, 1 dowel fracture 5 extracted teeth as a result of dubious treatment 3 excluded (noncompliance), 2 periapical pathology 30 failures (dowel debonding and periapical pathology) number for each type of failure not specified 2 periapical pathology, 1 dowel debonding, 1 crown debonding 3 dowel debonding, 4 marginal gap formation 4 dowel debonding 2 dowel debonding dowel debonding crown debonding 10 secondary caries 3 dowel debonding, 14 root fractures, 10 periapical pathology, 5 periodontitis, 3 unknown diagnosis 11 crown debonding, 14 root fractures, 10 periapical pathology, 5 periodontitis, 3 unknown diagnosis els can be made of different types of glasses: electrical glass, high-strength glass, or quartz fibers.39,64 The commonly used fibers are silica-based (50% to 70% SiO 2 ), in addition to other oxides.65 The GF dowel is available in different shapes: cylindrical, cylindroconical, or conical (Fig 2). An in vitro assessment of several GF dowel systems indicated that parallel-sided GF dowels are more retentive than tapered GF dowels.66 The composition of the glass fibers in the matrix tends to play an important role in the strength of the dowel. Newman et al45 compared the fracture resistance of two GF dowels containing different weight percentages of glass fibers. They found that the higher content of glass fibers in the dowel contributed to the greater strength displayed by the tested dowel. Laboratory test results The flexural strength of GF dowels is not related to the type of glass fiber used. One study67 evaluated the flexural strength of carbon-fiber, quartz-fiber, and glass-fiber dowels. It was found that the dowels behaved similarly because of the same concentration and type of the epoxy resin used to join the fibers together. The yield strength of GF, titanium, and zirconia dowels was also evaluated in vitro.68 The yield strength was significantly higher for the zirconia and titanium dowels when compared with GF dowels. Two studies69,70 indicated that the tensile bond strength between the composite resin core material and the GF dowel is less than that developed with a titanium dowel. Other studies62,71 indicated there was a good adhesive bond between the GF dowel and composite resin cements. The bonding of the core to the dowel can be improved by treating the dowel with airborne-particle abrasion.72 Similar results were obtained by treating the surface of the dowel with hydrogen peroxide and silane or hydrofluoric acid and silane.73,74 c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  529 Baba et al Nonmetallic Prefabricated Dowels Figure 2 Designs and shapes of available glass fiber-reinforced epoxy resin dowels. Similar to CF dowels, GF dowels have been shown in multiple studies45,75-77 to be less likely to cause fracture of the root at failure; however, studies40,78-81 have discussed the importance of the presence of a ferrule effect in achieving a high success rate. Clinical outcomes Eight studies have clinically evaluated GF dowels, and a wide range of failure percentages have been reported (Table 2). Failure rates have ranged from zero after a mean postplacement time of 2.3 years82 to a high of 11.4% after 1 to 2 years.83 Other reported failure rates were: 1.7% after 2.5 years,77 4% after 2.5 years,84 4.4% after a mean time of 3.8 years,56 6.2% after 2 years,81 7.4% after 2 years,85 and 11% after 7 to 11 years.58 The types of failures have been dowel loosening, periapical pathology, root fracture, crown debonding, dowel fracture, core failure, restoration fracture, and unknown reasons for failures. Dowel loosening was reported in six of the eight studies,56,58,77,81,83,85 whereas there was no reported loosening in two studies.82,84 Of the studies that reported dowel loosening, only five58,77,81,83,85 quantified the number of dowels that loosened. In these five studies, the following dowel loosening data were provided: 5 of 210 dowels loosened,58 2 of 205 dowels loosened,77 7 of 225 dowels loosened,81 2 of 105 dowels loosened,83 and 7 of 162 dowels loosened.85 Periapical pathology was reported in five56,58,81,84,85 of the eight studies with 11 of 210,58 7 of 225,81 4 of 100,84 and 5 of 16285 failures occurring this way. One study56 Table 2 Clinical studies for glass fiber-reinforced epoxy resin dowels (GF) Lead author Study length Dowels placed GF dowels placed % of clinical failure Ferrari M, 2000 1 to 6 yrs (mean 3.8) 1304 249 4.4% Malferrari S, 2003 Monticelli F, 2003 Naumann M, 2005 2.5 yrs 2 yrs 1 to 2 yrs 205 225 105 205 225 105 1.7% 6.2% 11.4% Grandini S, 2005 Naumann M, 2007 Cagidiaco MC, 2007 Ferrari M, 2007 2.5 yrs 2 to 3 yrs (mean 2.3) 2 yrs 7to 11 yrs 100 87 162 985 100 41 162 210 4% 0% 7.4% 11% 530 Types of failure 11 failures (dowel debonding and periapical pathology) number for each type of failure not specified 2 dowel debonding, 1 fractured restoration 8 dowel debonding, 6 periapical pathology 2 dowel debonding, 1 root fracture, 7 dowel fracture, 1 core failure, 1 other 4 periapical pathology, 5 partial loss of restoration No failures 7 dowel debonding, 5 periapical pathology 5 dowel debonding, 6 crown debonding, 11 periapical pathology, 1 root fracture c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  Baba et al Nonmetallic Prefabricated Dowels Table 3 Clinical studies for polyethylene fiber-reinforced dowels (PF) Lead author Study length Turker SB, 2007 1 to 6 yrs (mean 2.9) Dowels placed % of clinical failure 42 2.4% Types of failure 1 dowel debonding tooth structure.45 These results may be attributed to the manufacturer’s recommendations not to enlarge the root canals, not to remove undercuts present in the root canal, and form a 1.5to 2-mm crown ferrule. The presence of a large volume of core material and a sufficient dentin bonding area coronally seems to greatly affect the mean load-to-failure value of PF posts.45 Eskitascioglu et al89 evaluated two dowel systems using a fracture strength test and a finite element analysis. They found that stress accumulated along the cervical region of the tooth and along the buccal bone. Minimum stress was recorded within the PF dowel system. They suggested that the PF dowel could be advantageous for the restoration of teeth with apical resection. The use of PF dowels to restore endodontically treated teeth appears to be a promising alternative to stainless steel and zirconia dowels with respect to microleakage.90 Usumez et al90 compared in vitro the microleakage of three esthetic, adhesively luted dowel systems with a conventional dowel system. They found that the PF dowels and the GF dowels exhibited less microleakage compared to zirconia dowels. R Figure 3 (A) Polyethylene fiber-reinforced dowel, Ribbond - THM. (B) Close-up of polyethylene fiber-reinforced dowel material. indicated periapical pathology was encountered, but the number of failures produced from this source was not identified. Root fracture occurred in two of the studies,58,83 where 1 of 21058 and 1 of 10583 dowels fractured. Crown debonding was reported in one study58 and dowel fracture in one study.83 Polyethylene fiber-reinforced dowels Composition, properties, and laboratory test results Polyethylene fiber-reinforced dowels (PF) are made of ultrahigh molecular weight polyethylene-woven fiber ribbon (Ribbond, Ribbond Inc, Seattle, WA). It is not a dowel in the traditional sense; it is a polyethylene-woven fiber ribbon coated with a dentin bonding agent and packed into the canal, where it is then light polymerized in position.86-88 The Ribbond material has a three-dimensional (3D) structure due either to a leno weave or a triaxial architectural design (Fig 3A, B). These designs are composed of a great number of nodal intersections that prevent crack propagation and provide mechanical retention for the composite resin cement. When PF dowels were compared with metal dowels in the laboratory, the fiber-reinforced dowels reduced the incidence of vertical root fracture. The addition of a small-size prefabricated dowel to the PF dowel increased the strength of the dowel complex; however, the strength of the PF dowel did not approach that of a cast metal dowel.86 When compared to other fiber-reinforced composite dowel systems, the PF dowels were also found to protect the remaining Clinical outcomes One study91 has clinically evaluated PF dowels (Table 3). The failure rate was reported to be 2.4% after a mean time of 2.9 years. In this study 1 of 42 dowels loosened. Dowel loosening was reported to be the only cause of failure of the PF dowel. Zirconia dowels Composition and properties The trend toward the use of all-ceramic crowns has encouraged manufacturers to explore the development of all-ceramic dowels.92-95 A tooth-colored ceramic avoids the discoloration of tooth structure that can occur with metal dowels and produces optical properties comparable to all-ceramic crowns.96-99 One type of all-ceramic dowel is the zirconia dowel, composed of zirconium oxide (ZrO 2 ), an inert material used for a range of applications. Its high fracture toughness, high flexural strength, and excellent resistance to corrosion encouraged orthopedists to use it at articulation surfaces.100 Studies have suggested that zirconia specimens transplanted in animals were very stable after long-term aging, and there was no apparent degradation of the specimens.100,101-104 Zirconia (tetragonal zirconium polycrystals, TZP) exhibits phase transformation. Low-temperature degradation of TZP is known to occur as a result of spontaneous phase transformation of tetragonal zirconia to monoclinic phase during aging at 130◦ C to 300◦ C, possibly within a water environment. It has been reported that this degradation leads to a decrease in strength due to the formation of microcracks accompanying the c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  531 Baba et al Nonmetallic Prefabricated Dowels Laboratory test results Figure 4 Available shapes of zirconia dowels. phase transformation. To inhibit this phase transformation, certain oxides (magnesium, yttrium, or calcium oxide) are added to fully or partially stabilize the tetragonal phase of zirconia at room temperature. This mechanism is known as transformation toughening.95,101,105-107 The type of zirconia used for dental dowels is composed of TZP with 3% mol yttrium oxide (Y 2 O 3 ) and is called Y-TZP (Yttrium-stabilized tetragonal polycrystalline zirconia).95,108 Y-TZP is composed of a dense fine-grained structure (0.5 µm average diameter) that provides the dowel with toughness and a smooth surface.106,108,109 The dowel is extremely radiopaque and biocompatible, possesses high flexural strength and fracture toughness, and may act similar to steel.101-105,110-119 In addition, the dowel has low solubility116 and is not affected by thermocycling.44 The dowel is available in a cylindroconical shape (Fig 4). The zirconia dowel has a smooth surface configuration with no grooves, serrations, or roughness to enhance mechanical retention. As a result, the zirconia dowel does not bond well to composite resins and may not provide the best support for a brittle all-ceramic crown.69,120-123 Dietshi et al122 found that these dowels also have poor resin-bonding capabilities to dentin after dynamic loading and thermocycling due to the rigidity of the dowel. In a cyclic loading test performed in a wet environment, Mannocci et al123 found that the survival rate of zirconia dowels compared to fiber dowels was significantly lower. In vitro studies69,59,124,125 indicate that the smooth surface configuration of untreated zirconia dowels leads to failure at the cement/post interface. The vast majority of the cement remained in the root and was not attached to the zirconia dowels. Wegner and Kern126 evaluated the bond strength of composite resin cement to zirconia dowels. They found that the long-term bond strength of the composite resin cement to zirconia dowels is weak. Several studies126-129 found that acid etching and silanization of zirconia dowels does not improve the strength of the resin bond to the zirconia-based material because of little or no silica content in the dowel; however, tribochemical silica coating was found to increase the bond strength of composite resin to the zirconia dowel.130,131 Oblak et al132 compared the fracture resistance of prefabricated zirconia dowels after different surface treatments. They found that airborne-particle-abraded dowels exhibited significantly higher resistance to fracture than those ground with a diamond instrument. The use of heat-pressed glass instead of composite resin to form the core has been suggested.114,115,133 This approach may improve the physical properties of the all-ceramic dowel. When the mechanical properties of zirconia dowels were evaluated, it was reported that these dowels are very stiff and strong, with no plastic behavior.112,114 Pfeiffer et al68 found that the zirconia dowel had a significantly higher yield strength compared to titanium and GFR dowels. Several studies37,134,135 indicate that many commonly used dowels exhibit higher fracture resistance than zirconia dowels. In addition, if they fracture, the retained segment may not be retrievable, and the tooth would therefore not be restorable.39,135 Clinical outcomes Two studies136,137 have clinically evaluated zirconia dowels (Table 4). One study had no failures after a mean time of 2.4 years.134 In one study, the failure rate was reported to be 9% after a mean time of 4.8 years. Dowel loosening was reported to be the only cause of failure of the zirconia dowel. Table 4 Clinical studies for zirconia dowels Lead author Paul SJ, 2004 Nothdurft F, 2006 532 Study length 1 to 9 yrs (mean 4.8) 8 months to 3.6 yrs (mean 2.4) Dowels placed 145; Group 1: 79 direct composite, Group 2: 34 glass-ceramic core 30 % of clinical failure Types of failure Group 1: No failures Group 2: 9% 0% Group 2: dowel debonding No failures c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  Baba et al Conclusions Clinical practice trends have recently included nonmetallic prefabricated dowels such as carbon fiber-reinforced epoxy resin dowels, glass fiber-reinforced epoxy resin dowels, polyethylene fiber-reinforced dowels, and zirconia dowels. This literature review on in vitro investigations demonstrates favorable physical and mechanical properties of these dowels; however, clinically, there has been a wide range of reported failure percentages. Dowel loosening was reported in 16 of the 23 studies, making it the most commonly reported complication. Other complications (periapical pathology, root fracture, crown debonding, periodontitis, dowel fracture, and secondary caries) were reported less frequently than dowel loosening. A number of factors, such as the ferrule effect from the final restoration, humidity of the mouth, altering temperature changes, and fatigue loading, would likely play a role on the retentive strength of all prefabricated dowels in clinical service. Dowels with adequate ferrule substantially aid in preventing root fractures. It has been reported that a dowel does not strengthen a tooth, but it also does not weaken a tooth when there is a 2-mm ferrule.138 Since there is considerable variation in reported failure percentages, longer-term studies are needed to present data regarding all the types of complications identified in the literature. References 1. Ring ME: Dentistry: An Illustrated History. New York, NY, Abradale-Mosby, 1992 2. Evans G: A Practical Treatise on Artificial Crown-, Bridge-, and Porcelain-Work (ed 9). London, UK, Henry Kimpton, 1923, pp. 101 3. Hampson EL, Clark J: The post-retained crown. Dental Practice & Dent Rec 1958;8:130 4. Demas NC: Direct impression for cast Richmond crown using acetate crown forms. Dental Dig 1957;63:258 5. Goodacre CJ, Spolnik KJ: The prosthodontic management of endodontically treated teeth: a literature review. Part I. Success and failure data, treatment concepts. J Prosthodont 1994;3:243-250 6. Lewis R, Smith BG: A clinical survey of failed post retained crowns. Br Dent J 1988;165:95-97 7. Hatzikyriakos AH, Reisis GI, Tsingos N: A 3-year postoperative clinical evaluation of posts and cores beneath existing crowns. J Prosthet Dent 1992;67:454-458 8. Turner CH: The utilization of roots to carry post-retained crowns. J Oral Rehabil 1982;9:193-202 9. Bergman B, Lundquist P, Sjögren U, et al: Restorative and endodontic results after treatment with cast post and cores. J Prosthet Dent 1989;61:10-15 10. Mentink AG, Meeuwissen R, Käyser AF, et al: Survival rate and failure characteristics of the all metal post and core restoration. J Oral Rehabil 1993;20:455-461 11. Torbjörner A, Karlsson S, Ödman PA: Survival rate and failure characteristics for two post designs. J Prosthet Dent 1995;73:439-444 12. Turner CH: Post-retained crown failure: a survey. Dent Update 1982;9:221-229 13. Sorensen JA, Martinoff JF: Clinically significant factors in dowel design. J Prosthet Dent 1984;52:28-35 14. Creugers NH, Mentink AG, Käyser AF: An analysis of durability data on post and core restorations. J Dent 1993;21:281-284 Nonmetallic Prefabricated Dowels 15. Weine FS, Wax AH, Wenckus CS: Retrospective study of tapered, smooth post systems in place for 10 years or more. J Endod 1991;17:293-297 16. Roberts DH: The failure of retainers in bridge prostheses. An analysis of 2000 retainers. Br Dent J 1970;128:117-124 17. Wallerstedt D, Eliasson S, Sundström F: A follow-up study of screwpost-retained amalgam crowns. Swed Dent J 1984;8:165-170 18. Duret B, Renaud M, Duret F: Un nouveau concept de reconstitution corono-radiculaire: Le Composipost (1). Chir Dent Fr 1990;60:131-141 19. Duret B, Renaud M, Duret F: Un nouveau concept de reconstitution corono-radiculaire: Le Composipost (2). Chir Dent Fr 1990;60:69-77 20. Duret B, Renaud M, Duret F: Intérêt des matériaux à structure unidirectionnelle dans les reconstitutions corono-radiculaires. J Biomat Dent 1992;7:45-57 21. Rovatti L, Mason PN, Dallari A: New research on endodontic carbon-fiber posts. Minerva Stomatol 1994;43:557-563 22. Wennström J: The C-Post system. Compend Contin Educ Dent 1996;(Suppl 20):S80-S85 23. Trushkowsky RD: Coronoradicular rehabilitation with a carbon-fiber post. Compend Contin Educ Dent 1996;(Suppl. 20):S74-79 24. Viguie G, Malquarti G, Vincent B, et al: Epoxy/carbon composite resins in dentistry: mechanical properties related to fiber reinforcements. J Prosthet Dent 1994;72:245-249 25. Duret B, Duret F, Renaud M: Long-life physical property preservation and postendodontic rehabilitation with Composipost. Compend Contin Educ Dent 1996;(Suppl 20):S50-S60 26. Dallari A, Rovatti L: Six years of in vitro/in vivo experience with Composipost. Compend Contin Educ Dent 1996;(Suppl 20):S57-S63 27. Yazdanie N, Mahood M: Carbon fiber acrylic resin composite: an investigation of transverse strength. J Prosthet Dent 1985;54:543-547 28. King PA, Setchell DJ: An in vitro evaluation of a prototype CFRC prefabricated post developed for the restoration of pulpless teeth. J Oral Rehabil 1990;17:599-609 29. Malquarti G, Berruet RG, Bois D: Prosthetic use of carbon fiber-reinforced epoxy resin for esthetic crowns and fixed partial dentures. J Prosthet Dent 1990;63:251-257 30. Purton DE, Payne JA: Comparison of carbon fiber and stainless steel root canal posts. Quintessence Int 1996;27:93-97 31. Mannocci F, Sherriff M, Watson TF: Three-point bending test of fiber posts. J Endod 2001;27:758-761 32. Finger WJ, Ahlstrand WM: Fritz UB: radiopacity of fiber-reinforced resin posts. Am J Dent 2002;15:81-84 33. Love RM, Purton DG: The effect of serrations on carbon fiber posts-retention within the root canal, core retention, and post rigidity. Int J Prosthodont 1996;9:484-488 34. Torbjörner A, Karlsson S, Syverud M, et al: Carbon fiber reinforced root canal posts: mechanical and cytotoxic properties. Eur J Oral Sci 1996;104:605-611 35. Sidoli GE, King PA, Setchell DJ: An in vitro evaluation of carbon fiber-based post and core system. J Prosthet Dent 1997;78:5-9 36. Purton DG, Love RM: Rigidity and retention of carbon fiber versus stainless steel root canal posts. Int J Endod 1996;29:262-265 37. Cormier CJ, Burns DR, Moon P: In vitro comparison of the fracture resistance and failure mode of fiber, ceramic and conventional post systems at various stages of restoration. J Prosthodont 2001;10:16-36 c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  533 Baba et al Nonmetallic Prefabricated Dowels 38. Martinez-Insua A, da Silva L, Rilo B, et al: Comparison of the fracture resistance of pulpless teeth restored with a cast post and core or carbon-fiber post with a composite core. J Prosthet Dent 1998;80:527-532 39. Akkayan B: An in vitro study evaluating the effect of ferrule length on facture resistance of endodontically treated teeth restored with fiber-reinforced and zirconia dowel systems. Int J Prosthodont 2004;92:155-162 40. Dean JP, Jeansonne BG, Sarkar N: In vitro evaluation of a carbon fiber post. J Endod 1998;24:807-810 41. Fokkinga WA, Kreulen CM, Vallittu PK, et al: A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems. Int J Prosthodont 2004;17:476-482 42. Raygot CG, Chai J, Jameson DL: Fracture resistance and primary failure mode of endodontically treated restored with a carbon fiber-reinforced resin post system in vitro. Int J Prosthodont 2001;14:141-145 43. Isidor F, Odman P, Brøndum K: Intermittent loading of teeth restored using prefabricated carbon fiber posts. Int J Prosthodont 1996;9:131-136 44. Drummond JL, Bapna MS: Static and cyclic loading of fiber-reinforced dental resin. Dent Mater 2003;19:226-231 45. Newman MP, Yaman P, Dennison J, et al: Fracture resistance of endodontically treated teeth restored with composite posts. J Prosthet Dent 2003;89:360-367 46. Lassila LV, Tanner J, Le Bell AM, et al: Flexural properties of fiber reinforced root canal posts. Dent Mater 2004;20:29-36 47. McDonald AV, King PA, Setchell DJ: In vitro study to compare impact fracture resistance of intact root-treated teeth. Int Endod J 1990;23:304-312 48. Gesi A, Magnolfi S, Goracci C, et al: Comparison of two techniques for removing fiber posts. J Endod 2003;29:580-582 49. De Rijk WG: Removal of fiber posts from endodontically treated teeth. Am J Dent 2000;13(Spec No):19B-21B 50. Sakkal S: Carbon-fiber post removal technique. Compend Contin Educ Dent 1996;20:S86 51. Peters SB, Canby FL, Miller DA: Removal of a carbon fiber post system (Abstract). J Endod 1996;22:215 52. Abbott PV: Incidence of root fractures and methods used for post removal. Int Endod J 2002;35:63-67 53. Fredriksson M, Astback J, Pamenius M, et al: A retrospective study of 236 patients with teeth restored by carbon fiber-reinforced epoxy resin posts. J Prosthet Dent 1998;80:151-157 54. Segerstrom S, Astback J, Ekstrand KD: A retrospective long term study of teeth restored with prefabricated carbon fiber reinforced epoxy resin posts. Swed Dent J 2006;30:1-8 55. Hedlund SO, Johansson NG, Sjögren G: A retrospective study of pre-fabricated carbon fiber root canal posts. J Oral Rehabil 2003;30:1036-1040 56. Ferrari M, Vichi A, Mannocci F, et al: Retrospective study of the clinical performance of fiber posts. Am J Dent 2000;13(Spec No):9B-13B 57. Ferrari M, Vichi A, Garcia-Godoy F: Clinical evaluation of fiber-reinforced epoxy resin posts and cast post and cores. Am J Dent 2000;13(spec No):15B-18B 58. Ferrari M, Cagidiaco MC, Goracci C, et al: Long-term retrospective study of the clinical performance of fiber posts. Am J Dent 2007;20:287-291 59. Glazer B: Restoration of endodontically treated teeth with carbon fiber posts-a prospective study. J Can Dent Assoc 2000;66:613-618 534 60. Tidehag P, Lundström J, Larsson B, et al: A 7-year retrospective study of Composipost root canal posts (Abstract). J Dent Res 2004;83(Special Issue A) 61. Mannocci F, Qualtrough AJ, Worthington HV, et al: Randomized clinical comparison of endodontically treated teeth restored with amalgam or with fiber posts and resin composite: five-year results. Oper Dent 2005;30:9-15 62. Mannoci F, Bertelli E, Sherriff M, et al: Three-year clinical comparison of survival of endodontically treated teeth restored with either full cast coverage or with direct composite restoration. J Prosthet Dent 2002;88:297-301 63. King PA, Setchell DJ, Rees JS: Clinical evaluation of a carbon fiber reinforced endodontic post. J Oral Rehabil 2003;30:785-789 64. Murphy J: Reinforced Plastics Handbook. Oxford, UK, Elsevier, 1988 65. Chawla KK: Composite Materials: Science and Engineering (ed 2). New York, NY, Springer-Verlag, 1998 66. Teixeira ECN, Teixeira FB, Piasick JR, et al: An in vitro assessment of prefabricated fiber post systems. J Am Dent Assoc 2006;137:1006-1012 67. Galhano GA, Valandro LF, de Melo RM, et al: Evaluation of the flexural strength of carbon fiber, quartz fiber, and glass fiber-based posts. J Endod 2005;31:209-211 68. Pfeiffer P, Schulz A, Nergiz I, et al: Yield strength of zirconia and glass fibre-reinforced posts. J Oral Rehabil 2006;33:70-74 69. Al-harbi F, Nathanson D: In vitro assessment of retention of four esthetic dowels to resin core foundation and teeth. J Prosthet Dent 2003;90:547-555 70. Coelho Santos G Jr, El-Mowafy O, Henrique Rubo J: Diametral tensile strength of a resin composite core with nonmetallic prefabricated posts: an in vitro study. J Prosthet Dent 2004;91:335-341 71. Le Bell AM, Lassila LVJ, Kangasniemi I, et al: Bonding of fibre-reinforced composite post to root canal dentin. J Dent 2005;33:533-539 72. Balbosh A, Kern M: Effect of surface treatment on retention of glass-fiber endodontic posts. J Prosthet Dent 2006;95:218-223 73. Vano M, Goracci C, Monticelli F, et al: The adhesion between fibre posts and composite resin core: the evaluation of microtensile bond strength following various surface chemical treatments to posts. Int Endod J 2006;39:31-39 74. Monticelli F, Toledano M, Tay FR, et al: Post-surface conditioning improves interfacial adhesion in post/core restorations. Dent Mater 2006;22:602-609 75. Stricker EJ, Göhring TN: Influence of different posts and cores on marginal adaptation, fracture resistance, and fracture mode of composite resin crowns on human mandibular premolars. An in vitro study. J Dent 2006;34:326-335 76. Hu S, Osada T, Shimizu T, et al: Resistance to cyclic fatigue and fracture of structurally compromised root restored with different post and core restorations. Dent Mater J 2005;24:225-231 77. Malferrari S, Monaco C, Scotti R: Clinical evaluation of teeth restored with quartz fiber-reinforced epoxy resin posts. Int J Prosthodont 2003;16:39-44 78. Naumann M, Preuss A, Rosentritt M: Effect of incomplete crown ferrules on load capacity of endodontically treated maxillary incisors restored with fiber posts, composite build-ups, and all ceramic crowns: an in vitro evaluation after chewing simulation. Acta Odontol Scand 2006;64:31-36 79. Ng CCH, Dumbrigue HB, Al-Bayat MI, et al: Influence of remaining coronal tooth structure location on the fracture resistance of restored endodontically treated anterior teeth. J Prosthet Dent 2006;95:290-296 c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  Baba et al 80. Naumann M, Preuss A, Frankenberger R: Reinforcement effect of adhesively luted fiber reinforced composite versus titanium posts. Dent Mater 2006;23:138-144 81. Monticelli F, Grandini S, Goracci C, et al: Clinical behavior of translucent-fiber posts: a 2-year prospective study. Int J Prosthodont 2003;16:593-596 82. Naumann M, Sterzenbach G, Franke A, et al: Randomized controlled clinical pilot trial of titanium vs glass fiber prefabricated posts: preliminary results after up to 3 years. Int J Prosthodont 2007;20:499-503 83. Naumann M, Blankenstein F, Dietrich T: Survival of glass fiber-reinforced composite post restorations after 2 years-an observational clinical study. J Dent 2005;33:305-312 84. Grandini S, Goracci C, Tay FR, et al: Clinical evaluation of the use of fiber posts and direct resin restorations for endodontically treated teeth. Int J Prosthodont 2005;18:399404 85. Cagidiaco MC, Radovic I, Simonetti M, et al: Clinical performance of fiber post restorations in endodontically treated teeth: 2-year results. Int J Prosthodont 2007;20:293-298 86. Sirimai S, Riis DN, Morgano SM: An in vitro study of the fracture resistance and the incidence of vertical root fracture of pulpless teeth restored with six post-and-core systems. J Prosthet Dent 1999;81:262-269 87. Deliperi S, Bardwell DN, Coiana C: Reconstruction of devital teeth using direct fiber-reinforced composite resins: a case report. J Adhes Dent 2005;7:165-171 88. Eskitascioglu G, Belli S: The use of bondable reinforcement fiber for post-and-core buildup in an endodontically treated tooth: a case report. Quintessence Int 2002;33:549-551 89. Eskitascioglu G, Belli S, Kalkan M: Evaluation of two post core systems using two different methods (fracture strength test and a finite element analysis). J Endod 2002;28:629-633 90. Usumez A, Cobankara FK, Ozturk N, et al: Microleakage of endodontically treated teeth with different dowel systems. J Prosthet Dent 2004;92:163-169 91. 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;20:55-56 92. Meyenberg KH, Lüthy H, Schärer P: Zirconia posts: a new all-ceramic concept for non-vital abutment teeth. J Esthet Dent 1995;7:73-80 93. Zalkind M, Hochman N: Esthetic considerations in restoring endodontically treated teeth with posts and cores. J Prosthet Dent 1998;79:702-705 94. Zalkind M, Hochman N: Direct core buildup using a preformed crown and prefabricated zirconium oxide post. J Prosthet Dent 1998;80:730-732 95. Ahmad I: Yttrium-partially stabilized zirconium dioxide posts: an approach to restoring coronally compromised teeth. Int J Periodontics Restorative Dent 1998;18:454-465 96. Sorensen JA, Mito WT: Rationale and clinical technique for esthetic restoration of endodontically treated teeth with Cosmopost and IPS Empress post system. QDT 1998;21:8190 97. Michalakis KX, Hirayama H, Sfolkos J, et al: Light transmission of posts and cores used for the anterior esthetic region. Int J Periodontics Restorative Dent 2004;24:462-469 98. Carossa S, Lombardo S, Pera P, et al: Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation. Int J Prosthodont 2001;14:9-14 99. Ottl P, Hahn L, Lauer HCh, et al: Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post Nonmetallic Prefabricated Dowels 100. 101. 102. 103. 104. 105. 106. 107. 108. 109. 110. 111. 112. 113. 114. 115. 116. 117. 118. 119. 120. systems at monotonously increasing loads. J Oral Rehabil 2002;29:175-183 Cales B, Stefani Y, Lilley E: Long-term in vivo and in vitro aging of a zirconia ceramic used in orthopaedy. J Biomed Mat Res 1994;28:619-624 Christel P, Meunier A, Heller M, et al: Mechanical properties and short-term in vivo evaluation of yttrium-oxide-partially-stabilized zirconia. J Biomed Mater Res 1989;23:45-61 Ichikawa Y, Akagawa Y, Nikai H, et al: Tissue compatibility and stability of a new zirconia ceramic in vivo. J Prosthet Dent 1992;68:322-326 Purton DG, Love RM, Chandler NP: Rigidity and retention of ceramic root canal posts. Oper Dent 2000;25:223-227 Drouin JM, Cales B, Chevalier J, et al: Fatigue behavior of zirconia hip joint heads: experimental results and finite element analysis. J Biomed Mat Res 1997;34:149-155 Porter DL, Heuer AH: Mechanism of toughening partially stabilized zirconia ceramics (PSZ). J Am Ceram Soc 1977;60:183-184 Gubta TK, Lange FF, Bechtold JH: Effect of stress-induced phase transformation on the metastable tetragonal phase. J Mat Sci 1978;13:1464-1470 Guazzato M, Albakry M, Ringer SP, et al: Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental ceramics. Dent Mater 2004;20:449-456 Schweiger M, Frank M, Rheinburger V, et al: New sintered glass-ceramics based on apatite and zirconia endosseous implant in initial bone healing. J Prosthet Dent 1993;69:599604 Hulbert TK, Lange FF, Bechtold JH: Effect of stress-induced phase transformation on the metastable tetragonal phase. J Mat Sci 1978;13:1464-1470 Soares CJ, Mitsui FH, Neto FH, et al: Radiodensity evaluation of seven root post systems. Am J Dent 2005;18:57-60 Rosentritt M, Fürer C, Behr M, et al: Comparison of in vitro fracture strength of metallic and tooth-coloured posts and cores. J Oral Rehabil 2000;27:595-601 Asmussen E, Peutzfeldt A, Heitmann T: Stiffness, elastic limit, and strength of newer types of endodontic posts. J Dent 1999;27:275-278 Taira M, Nomura Y, Wakasa K, et al: Studies on fracture toughness of dental ceramics. J Oral Rehabil 1990;17:551563 Hochman N, Zalkind M: New all-ceramic indirect post-and-core system. J Prosthet Dent 1999;81:625-629 Dilmener FT, Sipahi C, Dalkiz M: Resistance of three new esthetic post-and-core systems to compressive loading. J Prosthet Dent 2006;95:130-136 Piconi C, Maccauro G: Zirconia as a ceramic biomaterial. Biomaterials 1999;20:1-25 Kakehashi Y, Luthy H, Naef R, et al: A new all-ceramic post and core system: clinical, technical, and in vitro results. Int J Periodontics Restorative Dent 1998;18:586-593 Koutayas SO, Kern M: All-ceramic posts and cores: the state of the art. Quintessence Int 1999;30:383-392 Heydecke G, Butz F, Hussein A, et al: Fracture strength after dynamic loading of endodontically treated teeth restored with different post-and-core systems. J Prosthet Dent 2002;87:438-445 Perdigao J, Geraldeli S, Lee IK: Push-out bond strength of tooth-colored posts bonded with different adhesive systems. Am J Dent 2004;17:422-426 c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536  535 Baba et al Nonmetallic Prefabricated Dowels 121. Cohen BI, Pagnillo MK, Newman I, et al: Retention of core material supported by three post head designs. J Prosthet Dent 2000;83:624-628 122. Dietschi D, Romelli M, Goretti A: Adaptation of adhesive posts and cores to dentin after fatigue testing. Int J Prosthodont 1997;10:498-507 123. Mannocci F, Ferrari M, Watson TF: Intermittent loading of teeth restored using quartz fiber, carbon-quartz fiber, and zirconium dioxide ceramic root canal posts. J Adhes Dent 1999;1:153-158 124. Baba NZ: The Effect of Eugenol and Non-Eugenol Endodontic Sealers on the Retention of Three Prefabricated Posts Cemented with a Resin Composite Cement (Thesis). Boston, MA, Boston University, 2000 125. Gernhardt CR, Bekes K, Schaller HG: Short-term retentive values of zirconium oxide posts cemented with glass ionomer and resin cement: an in vitro study and a case report. Quintessence Int 2005;36:593-601 126. Wegner SM, Kern M: Long-term resin bond strength to zirconia ceramic. J Adhes Dent 2000;2:139-147 127. Madani M, Chu FCS, McDonald AV, et al: Effects of surface treatments on shear bond strengths between a resin cement and an alumina core. J Prosthet Dent 2000;83:644-647 128. Blixt M, Adamczak E, Linden L, et al: Bonding to densely sintered alumina surfaces: effect of sandblasting and silica coating on shear bond strength of luting cements. Int J Prosthodont 2000;13:221-226 129. Ozcan M, Alkumru HN, Gemalmaz D: The effect of the surface treatment on the shear bond strength of luting cement to glass-infiltrated alumina ceramic. Int J Prosthodont 2001;14:335-339 536 View publication stats 130. Matinlinna JP, Lassila LV, Ozcan M, et al: An introduction to silanes and their clinical applications in dentistry. Int J Prosthodont 2004;17:155-164 131. Xible AA, de Jesus Tavares RR, de Araujo Cdos R, et al: Effect of silica coating and silanization on flexural and composite-resin bond strength of zirconia posts: an in vitro study. J Prosthet Dent 2006;95:224-229 132. Oblak C, Jevnikar P, Kosmac T, et al: Fracture resistance and reliability of new zirconia posts. J Prosthet Dent 2004;91:342-348 133. Butz F, Lennon AM, Heydecke G, et al: Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems: an in vitro study. Int J Prosthodont 2001;14:58-64 134. Mitsui FH, Marchi GM, Pimenta LA, et al: In vitro study of fracture resistance of bovine roots using different Intraradicular post systems. Quintessence Int 2004;35:612-616 135. Akkayan B, Gülmez T: Resistance to fracture of endodontically treated teeth restored with different post systems. J Prosthet Dent 2002;87:431-437 136. Nothdurft FP, Pospiech PR: Clinical evaluation of pulpless teeth restored with conventionally cemented zirconia posts: a pilot study. J Prosthet Dent 2006;95:311-314 137. Paul SJ, Werder P: Clinical success of zirconium oxide posts with resin composite or glass-ceramic cores in endodontically treated teeth: a 4-year retrospective study. Int J Prosthodont 2004;17:524-528 138. Tan PL, Aquilino SA, Gratton DG, et al: In vitro resistance of endodontically treated central incisors with varying ferrule heights and configurations. J Prosthet Dent 2005;93:331-336 c 2009 by The American College of Prosthodontists Journal of Prosthodontics 18 (2009) 527–536