Predictably Restoring Endodontically Treated Teeth

Predictably Restoring

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ABSTRACT

Endodontically treated teeth can be restored with a wide range of techniques of varying complexity. This paper presents a straightforward technique for the restoration of endodontically treated teeth that meet certain standards. Criteria are provided for the utilization of crowns, composite resins, cast gold post cores, amalgam or composite build-ups, and passive, parallel, small diameter stainless steel posts to restore these teeth. Consideration is given to ferrule design and its importance in achieving success. MeSH Key Words: dental restoration, permanent/methods; patient care planning; post and core technique; tooth, non-vital/therapy © J Can Dent Assoc 1998; 64:782-7 This article has been peer reviewed.

preceding paper1 provided the occlusal demands and other from the luting agent. It doesn’t criteria to help identify a loads such as FPDs or RPDs must absorb water and has a coefficient Apredictably restorable endo- be made prior to restoration. of thermal expansion (CTE) very dontically treated tooth. The crite- close to that of dentin. Typical CTE ria for an endodontically treated Choices in Build-up Materials for gold3 is 14 x 10-6; the CTE of tooth requiring a post is that the Any endodontically treated dentin4 is 10.6 x 10-6. Cast gold minimum length of remaining solid tooth will require a build-up, build-ups require a post for reten- tooth equal the sum of the biologic which may be as simple as closing tion and a substantial degree of width (2.5 mm), the ferrule length the access and pulp chamber on coronal destruction to be used. (2 mm), the apical seal (4 mm) and an intact anterior. The optimal Where applicable, this is the the post length, or 8.5 mm + post build-up material will have ade- build-up material of choice. quate strength, be biocompatible, length (Fig. 1). For teeth not requir- Amalgam exhibit a high level of resistance to ing a post, the requirements are for Amalgam offers strength. Its bacterial leakage, and be insolu- biologic width + ferrule length, or coefficient of thermal expansion is ble and dimensionally stable in 4.5 mm of supra-bony solid tooth. almost double that of dentin the presence of oral fluids. Bullard Solid tooth refers to dentin that is a (about 22 x 10-6, versus 10.6 x 10-6), and others2 showed that a coeffi- minimum of 1 mm thick after prep- and it is relatively stable in the aration. In addition, consideration cient of thermal expansion close presence of water. It offers a high- of the functional loads on a tooth is to that of the tooth reduces leak- level resistance to leakage once it essential. Single abutments sup- age, which is important. This has been in place for a period of porting precision attachment paper considers the four materials time due to the sealing effects of Journal removable partial dentures (RPDs), commonly utilized today for its corrosion products. Initial leak- distal extension RPDs or cantilever build-ups: cast gold, amalgam, age has been shown to be signifi- December composite, and glass ionomer. 1998 fixed partial dentures (FPDs) that cantly lower with dispersed phase Vol. 64 are endodontically treated or likely Cast Gold alloys than with spherical5 alloys. No. 11 to become so in the future should Cast gold offers strength. Its Bonding of amalgams is an option, be avoided. Careful assessment of resistance to leakage is derived and has the potential to strengthen

782 Canadian Dental Association Filename: mclean.qxd English 3/C

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbb aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab shrinkage results in stresses on the aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab Table I aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab bonding systems that may con- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab tribute to long-term bond failure. aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab On anterior teeth where a crown is aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab Coefficient of aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab not required and enamel margins aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab Tensile Young’s Thermal offer the promise of long-term Strength Modulus Expansion resistance to leakage, composite is MPa GPa x10-6 °C an excellent choice. With the poor Cast Gold Type IV3 701 to 786 69 to 110 14 long-term prognosis for dentin bonding agents and the corre- Amalgam 17 18 2 65.7 38 to 60 22 sponding risk of leakage, relying Composite Biscore12/Ticore11 55/35 13/18.5 25/35 on composite build-up materials 19 19 2 for leakage control seems risky and Glass Ionomer 12.4 9.4 14 unpredictable. On posterior teeth 20 21 4 Dentin 59.6 10.2 10.6 where composite is used as a build-up material, maintaining at least 2 mm between crown mar- time and cost to bond, and unan- gins and the build-up should swered questions as to the effects reduce leakage. The absorption of on long-term leakage, amalgam water with composites is a poten- bonding is contraindicated for tial concern due to the generation build-ups. On posterior teeth with of internal stresses, but it is difficult enough pulp chamber depth to to assess the clinical significance obviate the need for a post of this concern. In addition, it has (2 to 4 mm), amalgam is the mate- been shown that the mechanical rial of choice. Where a post is properties of composites degrade required to retain the build-up, with thermocycling and exposure amalgam is cheaper and faster to water.14 Kovarik and others15 than a cast gold core and often showed significantly shorter less destructive of tooth structure. fatigue life for composite build-up Composite supported crowns than for those Composite apparently offers with amalgam build-ups. While adequate strength clinically, its composites are fast and conve- Fig. 1: Minimum dimensions for a pre- ultimate strength being somewhat nient to use, in most instances they dicably restorable tooth. lower than that of amalgam. Its are inferior to amalgam and gold. resistance to leakage is almost Glass Ionomer the tooth and reduce leakage. totally dependent on the luting Glass ionomer filling materials 6 Christensen recommends that agent, and the ability of dentin offer a low level of leakage,16,2 a rel- bonding of amalgam restorations bonding agents to prevent leakage atively weak dentin bond and a low be routine; however, with root- over the long term is unproven. level of mechanical strength treated teeth, sensitivity is not an Burrow and others10 showed a (Table I). They offer the appeal of issue and the additional strength degradation of dentin bond fluoride release to reduce decay obtained is apparently transient. strength in vitro over three years potential, but there is minimal evi- Santos and Meiers7 found no sig- almost to the level of an unbonded dence that this has any clinical significant strengthening of teeth restoration. If this is typical clini- nificance. Kovarik and others15 with amalgam bond after thermo- cally, then the long-term ability of fatigue-tested crowns with amal- cycling, and Bonilla and White8 dentin adhesives to reduce leakage gam, composite and glass ionomer found short-term increases in cannot be relied on, which means cores, and found that amalgam was strength that disappeared after composite build-ups must rely on significantly stronger than compos- 500-day storage or load cycling. mechanical retention as do amal- ite and that glass ionomer had inad- As apparently the bond of amalgam build-ups. The coefficient of equate strength as a core build-up. gam to dentin will ultimately thermal expansion for most mod- Because of its weak mechanical degrade, there is concern about ern self-polymerising composite properties, glass ionomer has little increased leakage after bond fail- build-up materials is significantly to offer as a build-up material and ure. The bonded surface of the higher than that of tooth; examples should be reserved for limited amalgam may be more corrosion include Ticore11 by EDS at 34 x applications such as blocking out Journal resistant than an unbonded amal- 10-6, and BisCore12 by Bisco at 25 minor undercuts. -6 December gam, leading to the risk of x 10 . In addition, composites Ranking of Build-up Materials 1998 increased leakage on a long-term show significant setting shrinkage. When a post is required and Vol. 64 basis.9 Given the short-term Sakaguchi and others13 showed there is sufficient coronal destruc- No. 11 nature of the bond, the additional 0.2% post gel contraction. This tion to allow cast gold without sig-

Canadian Dental Association 783 Filename: mclean.qxd English 2/C

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In situ- closing the access with a compos- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab ations where a build-up can be ite resin. Once distal to the cuspid, aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab retained without a post, or where placement of a cast restoration that aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab a post is needed but the place- shoes the cusps improves the odds ment of a cast gold core build-up of success.24 Placement of a crown would require significant removal on an anterior tooth is indicated of additional tooth structure, when there is extensive coronal amalgam would be the material of destruction or the need for occlusal choice. In teeth where simple clo- change, or for esthetic reasons. In sure of the access preparation is such situations, the mechanical all that is required and enamel and esthetic properties of porce- margins offer the potential for lain, porcelain on gold, or modified long-term resistance to leakage, resin crowns such as Vectris-rein- composite resin is the material of forced Targis crowns offer advan- choice. Glass ionomer is not suit- tages over large composites. able for build-ups. Considerable focus has been Fig. 2: Ferrule criteria and dimentions. How to Retain the Build-up placed on the potential for coronal leakage to cause the failure of oth- With the use of cast gold, a and Sorensen33 have shown the erwise acceptable endodontic post is mandatory for retention. importance of at least 1 mm of treatment. Torabinejad and oth- With amalgam or composite, the almost parallel wall preparation. 26 27,28 retentive options are pins, posts ers, Swanson and Madison, The study by Freeman and others 29 and mechanical undercuts such as and Khayat and others showed highlights the misconceptions as to offered by a pulp chamber. The that leakage will occur corono-api- what constitutes a ferrule. Given use of pins to retain build-ups car- cally along the obturated canal if the realities of intraoral tooth prepa- ries the risk of microfracture and the coronal access is not effectively ration, a minimum of 2 mm of introduces stress into the adjacent sealed. In a retrospective study, Ray preparation length on solid tooth is 30 dentin. Teeth that require pins or and Trope have shown that the recommended to ensure an ade- posts to retain build-ups have long-term success of a restoration quate length of parallel wall to already suffered significant coro- depends more on the quality of the achieve an effective ferrule (Fig. 2). nal destruction. Caputo21 recom- final restoration than on the quality When to Place a Post mends a minimum of 1 mm of of the endodontics. The impor- Posts have one purpose, to solid dentin to surround a pin, yet tance of the quality of the final retain a build-up on a tooth. There this thickness is rarely available to restoration and it’s ability to mini- is compelling evidence that they retain build-ups on root-treated mize leakage cannot be overstated. do not strengthen teeth.34-36 The teeth. The undercuts in pulp Ferrule Design chambers can be used to retain use of certain post designs can The importance of ferrule, its predispose them to catastrophic build-ups; Nayyar and others22 design and execution cannot be failure, as shown by Sorensen and and Kane and others23 have ignored. A recent in vitro study by Engelman.33 Based on this shown that pulp chamber depths Freeman and others31 compared premise, posts function primarily of 2 to 4 mm offer adequate reten- leakage under post-retained com- in tension. A relatively small diam- tion for an amalgam build-up posite cores and cast gold post eter post has ample strength in without pins or posts. The use of cores and the number of cycles tension to retain any crown. The slots or dovetails cut into dentin to until a strain gage detected move- rather loose adaptation of a small retain the amalgam has appeal but ment between the artificial crown diameter post in a canal does not requires the destruction of more and the root. Movement between reduce retention, as shown by tooth structure. There is also a risk crown and root was measured very 37 that these retentive devices will be Chan and others. Standlee and early in the experiment, on average 38 removed or weakened during others showed that post diame- after only a few hundred cycles. In crown preparation. ter was not a major factor in reten- the experimental design, tooth Posts offer the ability to retain tion and the parallel-sided para preparation “extended 1 mm apical the build-up and, if carefully post was more retentive than a to the core-tooth interface, thereby placed, remove little tooth struc- smooth-tapered dowel design. In providing a 1 mm ferrule on tooth situations where an artificial ture. They are also removable for 31 orthograde endodontic retreatment. structure.” In reality, when the crown breaks off and either shears Journal teeth were sectioned and the mar- off the post or dislodges it, there is The Choice of Final Restoration gins examined, there was little or at least the potential for retreat- December 1998 Crowns placed on anterior teeth no ferrule present. The cross-sec- ment. Utilization of larger posts Vol. 64 do not make teeth inherently tions effectively showed a cham- requires the removal of additional No. 11 stronger.24,25 In the absence of sig- fered or bevelled margin that was tooth structure and weakens the nificant coronal destruction, a far from parallel. Both Barkhordar32 tooth,39-41 increasing the risk of

784 Canadian Dental Association aaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbb aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab catastrophic failure and of having removal for retreatment (appar- small bicuspid teeth requiring a aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab a tooth that is unrestorable. ently valid), a modulus of elastic- post, the choice is a cast post core aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab ity (Young’s) close to natural design. When used, a cast post aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab Passive Metal Posts aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab tooth, which decreases the risk of core should utilize a high-strength aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab Passive metal posts include par- stress concentrations, and a high type IV gold alloy or a similar high- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab allel, tapered, and custom posts. level of retention because the post strength non-precious alloy. Pre- 42 Weine showed a 94% success bonds to the resin system used to formed posts with a direct build-up rate with smooth-tapered posts retain it in the root. Sidoli and work very well in posterior teeth over 10 years. In a study of 1,273 others25 showed in vivo crowns where there is room for sufficient teeth restored a minimum of one retained with composiposts failed bulk of build-up material. Canal 43 year, Sorensen and Martinoff under 63% of the load required to angulation is infrequently a prob- showed a 97% success rate for any break para-post retained crowns. lem. Preformed posts with an post crown restoration in which the Purton and Love47 showed amalgam build-up are often more post length equalled or exceeded bonded para-posts to have 168% conservative of tooth structure the crown length. Torbjorner and of the retention of carbon fibre than cast gold in posterior teeth. others44 reviewed almost 800 posts posts. The suggestion that a They are generally less expensive after four years, and parallel posts Young’s modulus close to tooth is and quicker to fabricate. showed half the failure rate of cus- an advantage is questionable With preformed posts, stainless tom-cast tapered posts. Post length when the coronal restoration will steel (SS) posts are stronger for any is key and ideally should extend be a rigid cast metal or ceramic given size than titanium posts and into the root past the crown margin crown. The increased flexibility in they are more radiopaque. This by an amount equal to the length of the coronal and radicular tooth radiopacity is an advantage, mak- the crown. Conservation of dentin structure resulting from these ing a post easier to identify clini- is critical in post placement and posts should cause increased, not cally. The Parapost system by dictates a post diameter that decreased, stress concentrations Whaledent is currently the only requires minimal canal instrumen- at the crown margins. Despite the passive, parallel, SS preformed tation. Parallel post designs offer preceding, Fredriksson48 and oth- post series on the market available increased retention over tapered ers showed an almost 100% suc- in small diameters. The system designs.37,38 cess rate in a retrospective study provides 0.9, 1, 1.14 and of 236 teeth restored with carbon 1.25 mm diameter posts in addi- Active Posts fibre posts for over two years. Car- tion to larger diameters. Active post designs rely on bon fibre posts may offer promise, some form of mechanical engage- but with conflicting evidence and Post Head Design ment of cutting flutes into dentin limited clinical trials, they cannot Where a preformed post is used to gain increased retention. One be recommended for routine use. to retain a composite or amalgam active post design, the Flexi-Post The clinical evidence is clear in build-up, the ability of the build-up by EDS, purports to provide the both in vivo and in vitro studies material to attach itself to the post retention of an active post while that adequately designed passive is important. Chang and Millstein49 avoiding the potential stress on the posts deliver highly predictable tested the retention of Paraposts root of a conventional solid active results. Passive, small diameter, and Unity posts by Whaledent, and post design. As pointed out by parallel post designs are pre- the Flexi-post by EDS with two 45 Manning and others, for the dictable and simple to use and are types of composite build-up as well Flexi-Post design, the change in the design of choice. as amalgam. They found that the diameter provided by the slot in amalgam core was significantly the post is minimal. The post com- Cast or Preformed Post more retentive than either compos- presses to an ellipse whose great- With a passive round post ite core. Their results show the est width is almost equal to the design as a starting point, the importance of the retentive features original diameter. Standlee and question is whether to use a cast built into a post head. When trim- Caputo46 showed Flexi-Posts gen- post core or a preformed post- ming preformed posts, it is essential erated significant stress levels retained amalgam or composite that this feature be retained. Use of comparable with other active post build-up. preformed posts without such fea- designs. While the additional A cast post design is indicated tures should be avoided. retention of an active post has where alignment of the proposed appeal, any active post design crown is significantly different Post Cements induces more stress into a root from the inclination of the canal, From the perspective of the abil- than a passive design. which is often the case with ante- ity to retrieve the post in the case of rior teeth. With most anterior, and fracture or for orthograde endodon- Journal Carbon Fibre Posts some bicuspid teeth, there is also tic retreatment, the use of a resin December There has been a lot of interest inadequate room for sufficient cement is contraindicated. In addi- 1998 in carbon fibre post systems, bulk of build-up material around tion, the ability of resin cements to Vol. 64 specifically the composipost. the post to provide a solid unit. provide long-term resistance to No. 11 These claims include ease of Thus for most anterior teeth and coronal leakage is dependent not

Canadian Dental Association 785 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbb aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab The author has no declared aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab only on the longevity of the dentin tion of compromised endodonti- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab financial interest in any company aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab bond but also on the bond to the cally treated teeth nor indicate aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab manufacturing the types of prod- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab post. Both are unproven. There is how to restore structural integrity aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab ucts mentioned in this article. aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab little or no evidence that the to existing crowns that have had aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab increased retention offered by an endodontic access placed these cements is a factor in clinical through them. Both areas need References success where adequate post research and guidelines to aid the 1. McLean AGR. Criteria for the pre- length can be obtained. In fact, clinician in restoring these teeth. dictably restorable endodontically Standlee and Caputo50 warn that Summary treated tooth. J Can Dent Assoc too much retention may predispose When restoring an endodonti- 1998; 64:652-6. a tooth to fracture. ZnPO4, and 2. Bullard RH, Leinfelder KF, Russell resin modified glass ionomer cally treated tooth, the first step is CM. Effect of coefficient of thermal cements such as vitremer luting, to assess the level of predictability involved in the restoration. If the expansion on microleakage. JADA offer adequate retention and resis- 1998; 116:871-4. tance to leakage and simplify post tooth meets the previously out- removal. Pure glass ionomer lined criteria, then the following 3. Proprietary data provided by Williams, Amherst, NY. cements should work as well but approach is recommended. are sensitive to moisture or the lack On anterior teeth with intact 4. Xu HC, Liu WY, Wang T. Mea- of it in a canal when setting. The crowns, simply closing the access surement of thermal expansion coef- use of resin cements should be with composite is as successful as ficient of human teeth. Aust Dent J reserved for cases outside of these placing a crown. Where significant 1989; 34:530-5. criteria where adequate post length coronal destruction has occurred, 5. Mahler DB, Bryant RW. and retention are not available. use a crown with a cast post core. Microleakage of amalgam alloys: An A crown is indicated on all update. JADA 1996; 127:1351-6. Post Hole Preparation endodontically treated posterior 6. Christensen GJ. Should you and It is possible to disturb the api- teeth. In preparing the tooth, par- can you afford to bond amalgams? cal seal during post-hole prepara- allel ferrule walls are essential and JADA 1994; 125:1381-2. should be a minimum of 2 mm tion. A 4 to 5 mm apical seal of 7. Santos AC, Meiers JC. Fracture gutta-percha is recommended long apico-coronally. In addition, resistance of premolars with MOD based on research by several the thickness of the remaining amalgam restorations lined with 51-53 51 52 authors. Mattison, Camp, dentin should be no less than amalgam bond. Oper Dent Suchina and Ludington,54 and 1 mm on the buccal and lingual 1994;19:2-6. 55 wall areas, and optimally inter- Haddix and others reviewed a 8. Bonilla E, White SN. Fatigue of range of techniques for post hole proximally as well. resin-bonded amalgam restorations. preparation and the removal of For the build-up use amalgam, Oper Dent 1996; 21:122-6. and where inadequate pulp cham- gutta-percha. Mattison and others, 9. Meiers JC, Turner EW. Microleak- ber depth remains to retain the Camp and Todd, and Suchina and age of dentin/amalgam alloy bond- build-up, a preformed post should Ludington found little difference ing agents: Results after 1 year. Oper be placed. On some posterior between mechanical removal with Dent 1998; 23:30-3. Gates-Glidden burs and removal teeth such as small upper first bicuspids, cast gold post cores will 10. Burrow MF, Satoh M, Tagami J. with a hot plugger, while Haddix Dentin bond durability after three be preferable to amalgam where and others found that removal with years using a dentin bonding agent tooth size prevents adequate bulk a warm plugger produced the least with and without printing. Dent of build-up around the post. leakage. Gates-Glidden burs offer Mater 1996; 12:302-7. a simple and predictable method Where a post is needed, use a 11. Proprietary data provided by Es- for the removal of gutta-percha. small diameter, passive round post requiring a minimum of dentin sential Dental Systems. Discussion removal and use a post length that 12. Proprietary data provided by The restoration of anterior teeth extends into the root past the Bisco Dental. needs better criteria on which to crown margin by the length of the 13. Sakaguchi RL, Sasik CT, Bunczak base restorative decisions. Even crown. Cement the post with MA, Douglas WH. Strain gauge knowing when to place a crown ZnPO4 or a hybrid resin/glass method for measuring polymeriza- on an anterior tooth is very hard to ionomer cement, leaving an api- tion contraction of composite determine. The issue of leakage cal seal of 4 mm of gutta-percha. ■ restoratives. J Dent 1991; 19:312-6. with endodontically treated teeth 14. Arikawa H, Kuwahata H, Seki H, is of concern: how much leakage Kanie T, Fujii K, Inoue K. Deteriora- Journal is too much? Does the degradation Dr. Alex McLean is in private tion of mechanical properties of of dentin bonding agents over time general practice in Kamloops, composite resins. Dent Mater J December 1998 present a concern for clinically sig- British Columbia. 1995; 14:78-83. Vol. 64 nificant leakage under build-ups or Reprint requests to: Dr. Alex 15. Kovarik RE, Breeding LC, No. 11 along posts? This paper does not McLean, 201-418 St. Paul St., Caughman WF. Fatigue life of three provide guidelines for the restora- Kamloops, BC V2C 2J6. core materials under simulated

786 Canadian Dental Association aaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbb aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab chewing conditions. J Prosthet Dent 30. Ray HA, Trope M. Periapical sta- 43. Sorensen JA, Martinoff JT. Clini- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab 1992; 68:584-90. tus of endodontically treated teeth in cally significant factors in dowel aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab relation to the technical quality of the design. J Prosthet Dent 1984; 52:28- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab 16. Carlson TJ, Naguib EA, Cochran aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab root filling and the coronal restora- aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab 35. aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab MA, Lund MR. A comparison of aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab tion. Int Endod J 1995; 28:12-8. aaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbab glass ionomer cements used to 44. Torbjorner A, Karlsson S, repair cast restorations. Oper Dent 31. Freeman MA, Nicholls JI, Kydd Odman PA. Survival rate and failure 1990; 15:162-6. WL, Harrington GW. Leakage asso- characteristics for two post designs. 17. Craig RG. (1997) Restorative den- ciated with load fatigue-induced pre- J Prosthet Dent 1995; 73:439-44. liminary failure of full crowns placed tal materials. CV Mosby St. Louis. 45. Manning KE, Yu DC, Yu HC, over three different post and core 18. Bryant RW, Mahler DB. Modu- systems. J Endod 1998; 24:26-32. Kwan EW. Factors to consider for lus of elasticity in bending of com- predictable post and core build-ups posites and amalgams. J Prosthet 32. Barkhordar RA, Radke R, Abbasi of endodontically treated teeth. Part J. Effect of metal collars on resis- Dent 1986; 56:243-8. II: Clinical application of basic con- tance of endodontically treated cepts. J Can Dent Assoc 1995; 19. Cohen BI, Pagnillo M, Musikant teeth to root fracture. J Prosthet Dent 61:696-707. BL, Deutsch AS, Cofrancesco G. 1989; 61:676-8. Comparison of the Young’s modulus 46. Standlee JP, Caputo AA. The 33. Sorensen JA, Engelman MJ. Fer- for six reinforced dental materials. retentive and stress distributing rule design and fracture resistance of Oral Health 1997; 87:47-8. properties of split threaded endodontically treated teeth. J Pros- 20. Huang TJ, Schilder H, Nathanson thet Dent 1990; 63:529-36. endodontic dowels. J Prosthet Dent D. Effects of moisture content and 1992; 68:436-42. 34. Guzy GE, Nicholls JI. In vitro endodontic treatment on some comparison of intact endodontically 47. Purton DG, Love RM. Rigidity mechanical properties of human treated teeth with and without endo- and retention of carbon fibre versus dentin. J Endod 1992; 18:209-15. post reinforcement. J Prosthet Dent stainless steel root canal posts. Int 21. Caputo AA, Standlee JP. Pins and 1979; 42:39-44. Endod J 1996; 29:262-5. posts – why, when and how. Dent 35. Assif D, Bitenski A, Pilo R, Oren 48. Fredriksson M, Astback J, Pame- Clin North Am 1976; 20:299-311. E. Effect of post design on resistance nius M, Arvidson K. A retrospective 22. Nayyar A, Walton RE, Leonard to fracture of endodontically treated study of 236 patients with teeth LA. An amalgam coronal-radicular teeth with complete crowns. J Pros- restored by carbon fibre reinforced dowel and core technique for thet Dent 1993; 69:36-40. epoxy resin posts. J Prosthet Dent endodontically treated posterior 36. Trope M, Maltz DO, Tronstad L. 1998; 80:151-7. teeth. J Prosthet Dent 1980; 43:511-5. Resistance to fracture of restored 49. Chang WC, Millstein PL. Effect 23. Kane JJ, Burgess JO, Summitt JB. endodontically treated teeth. Endod of design of prefabricated post heads Fracture resistance of amalgam coro- Dent Traumatol 1985; 1:108-11. on core materials. J Prosthet Dent nal-radicular restorations. J Prosthet 37. Chan FW, Harcourt JK, Brock- 1993; 69:475-82. Dent 1990; 63:607-13. hurst PJ. The effect of post adaptation 50. Standlee JP, Caputo AA. 24. Sorensen JA, Martinoff JT. Intra- in the root canal on retention of posts Endodontic dowel retention with coronal reinforcement and coronal cemented with various cements. resinous cements. J Prosthet Dent coverage: A study of endodontically 38. Standlee JP, Caputo AA, Hanson 1992; 68:913-7. treated teeth. J Prosthet Dent 1984; EC. Retention of endodontic dowels: 51:780-4. 51. Mattison GD, Delivanis PD, Effect of cement, dowel length, Thacker RW, Hassel KJ. Effect of post 25. Sidoli GE, King PA, Setchell DJ. diameter, and design. J Prosthet preparation on the apical seal. An in vitro evaluation of a carbon Dent 1978; 39:400-5. J Prosthet Dent 1984; 51:785-9. fibre-based post and core system. 39. Leary JM, Aquilino SA, Svare 52. Camp LR, Todd MJ. The effect of J Prosthet Dent 1997; 78:5-9. CW. An evaluation of post length dowel preparation on the apical seal 26. Torabinejad M, Ung B, Kettering within the elastic limits of dentin. of three common obturation tech- JD. In vitro bacterial penetration of J Prosthet Dent 1987; 57:277-81. coronally unsealed endodontically niques. J Prosthet Dent 1983; 40. Hunter AJ, Feiglin B, Williams JF. 50:664-6. treated teeth. J Endod 1990; 16:566-9. Effect of post placement on 27. Swanson K, Madison S. An evalu- endodontically treated teeth. J Pros- 53. Goodacre CJ, Spolnik KJ. The ation of coronal microleakage in thet Dent 1989; 62:166-72. prosthodontic management of endodontically treated teeth: A literature endodontically treated teeth. Part I: 41. Tjan AH, Whang SB. Resistance review. Part II: Maintaining the api- Time periods. J Endod 1987; 13:56-9. to root fracture on dowel channels cal seal. J Prosthodont 1995; 4:51-3. 28. Madison S, Swanson K. An evalua- with various thicknesses of buccal tion of coronal microleakage in dentin walls. J Prosthet Dent 1985; 54. Suchina JA, Ludington JR. endodontically treated teeth. Part II: 53:496-500. Dowel space preparation and the Journal Sealer types. J Endod 1987; 13:109-12. apical seal. J Endod 1985; 11:11-7. 42. Weine FS, Wax AH, Wenckus December 29. Khayat A, Lee SJ, Torabinejad M. CS. Retrospective study of tapered, 55. Haddix JE, Mattison GD, Shulman 1998 Human saliva penetration of coro- smooth post systems in place for 10 CA, Pink FE. 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