2 Amalgam had the lowest failure rate, Amalgam, resin composite, and glass ionomer in combination with a prefabricated postAmalgam had the lowest failure rate,Glass ionomer core buildup materials caused the greatest number of failuresR. E. Kovarik, L. C. Breeding, and W. F. Caughman, “Fatigue life of three core materials under simulated chewing conditions,” The Journal of Prosthetic Dentistry, vol. 68, no. 4, pp. 584–590, 1992
3 Some studies supported the use of amalgam dowels in the root canals Tamse compared 49 mesial roots extracted due to vertical fractures with 52 mesial mandibular roots without fractures,and found that 67.3% of the vertically fractured roots had an amalgam dowel in the coronal part (1-2mm) of the root.
4 In another study, endodontically treated teeth not crowned after obturation were lost 6 times more often than teeth crowned after obturationS. A. Aquilino and D. J. Caplan, “Relationship between crown placement and the survival of endodontically treated teeth,” The Journal of Prosthetic Dentistry, vol. 87, no. 3, pp. 256–263, 2002.
5 A 10-year prospective clinical trial, showed 94% survival rate of metal post-and-cores with a crown G. Heydecke andM. C. Peters, “The restoration of endodontically treated, single-rooted teeth with cast or direct posts and cores: a systematic review,” The Journal of Prosthetic Dentistry, vol. 87, no. 4, pp. 380–386, 2002.
6 Another 17-year controlled prospective study showed that the type of core restorations under the crowns had no effect on the survival rate of 307 endodontically treated teethW. A. Fokkinga, C. M. Kreulen, E. M. Bronkhorst, and N. H. J. Creugers, “Up to 17-year controlled clinical study on postand- cores and covering crowns,” Journal of Dentistry, vol. 35, no. 10, pp. 778–786, 2007.
7 Post-coreThe use of posts does not reinforce endodontically treated teeth and some reports even show that teeth which were restored without a post and core are less susceptible to fracture than teeth with post and coreA. Smidt and E. Venezia, “Techniques for immediate core buildup of endodontically treated teeth,” Quintessence International, vol. 34, no. 4, pp. 258–268, 2003
8 Post-coreIts success relies on the success of the entire system and vice versa.For anterior restorations, consider using a ceramic or light-colored fiber post made of quartz, silicone or glass fibers.
9 Post ShapePosts come in three basic shapes: parallel, tapered, and parallel-tapered
10 Parallel Parallel posts are more retentive than tapered ones. They seem less likely to cause root fractures, distributing stresses evenly along their length.However, parallel posts require removal of more tooth structure than tapered ones and, therefore, may not be suitable for roots with thin walls.
11 TaperedTapered posts allow for minimal dentin removal since most roots themselves are tapered.The stresses absorbed by these posts are concentrated in the apexCreating a wedging effect and increasing the risk of vertical root fracture.Because of this increased risk when tapered posts fail, they are more likely to leave the tooth unrestorable.
12 Parallel-taperedAdvantages of both designs with few reported disadvantages.This post has a parallel shaft, tapering at the apical end.This mix achieves retention associated with parallel sides, while allowing tooth preservation at the apex.
13 Length and DiameterPost retention improves with increases in post length, rather than diameter.An increase in post length with a minimum diameter preserves tooth structure and reduces shear stresses and risk of fracture.
15 Diameter is important for strength and resistance to post fracture Sequential use of post twist drills, starting with narrowest and working up to the desired post diameter, can be useful in minimizing tooth loss during post-space preparation.[
16 The groove is normally located where the root is bulkiest, usually on its lingual aspect. Rotational resistance in an extensively damaged tooth can be obtained by preparing a small groove in the root canal. This must be in the path of placement of the post and core.
17 Influence of post and cores on light transmission through all-ceramic crowns Some ceramic systems are semi-translucent (IPS Empress®, Ivoclar Vivadent)Others are semi-opaque (In-Ceram®, Vident, Brea, CA).A traditional metal post (gold or titanium) results in poor esthetics because of the lack of light transmission.
18 . Metallic posts also create a light blue/gray appearance at the gingival margin, possibly as a result of shadows.
19 Metal post Esthetic Corrosion reactions Taste Oral burning Oral pain Sensitization and other allergic reactionsHayashi Y, Nakamura S. Clinical application of energydispersive x-ray microanalysis for nondestructivelyconfirming dental metal allergens. Oral Surg Oral MedOral Pathol 1994; 77:
22 Radiopacity FRC Postec shows reduced radiopacity Used in conjunction with Variolink II provides additional x-ray identification
23 RemovalFRC Postec can be removed with a rotary instrument if retreatment is required
24 Zirconia posts Meyenberg Good chemical stability Mechanical strength High toughnessColor similar to that of natural teethAhmad I. Yttrium–partially stabilized zirconium dioxideposts: an approach to restoring coronally compromisednonvital teeth. Int J Periodontics Restor Dent 1998; 18:
25 Zirconia posts Nearly impossible to remove Removal of zirconia post by ultrasonic causes temperature rise of the post and on the root surface
26 Zirconia postCormier et al: fracture strength of zirconia post varied according to the different stages of tooth restoration.When the post alone was bonded into tooth, fracture strength was N;when the post was bonded into tooth with core buildup, fracture strength was N;with post and core buildup as well as full veneer restoration, fracture strength was NCormier 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:
27 The bond strengths of luting agents to zirconia posts were measured without bonding to any tooth structure, and it was shown that a dual-cured resin cement,Panavia (Kuraray, Osaka), produced better results than other cement typesSahmali S, Demirel F, Saygili G. Comparison of in vitro tensile bond strengths of luting cements to metallic and tooth-colored posts. Int J Periodontics Restor Dent 2004; 24:
28 The reviewed studies suggested that FRC and zirconia posts might be the preferred clinical choice for preventing coronal microleakageJung SH, Min KS, Chang HS, Park SD, Kwon SN, Bae JM. Microleakage and fracture patterns of teeth restored with different posts under dynamic loading. J Prosthet Dent 2007; 98:Reid LC, Kazemi RB, Meiers JC. Effect of fatigue testing on core integrity and post microleakage of teeth restore with different post systems. J Endod 2003; 29:Usumez A, Cobankara FK, Ozturk N, Eskitascioglu G, Belli S. Microleakage of endodontically treated teeth with different dowel systems. J Prosthet Dent 2004; 92:
29 zirconia posts showed the highest radiodensity level, followed by metallic posts, carbon fiber posts, glass fiber posts, and carbon fiber post covered with quartz fiber.
30 In a study by Dietschi et al. It was reported that the carbon fiber post presented the lowest marginal gap proportion (7.11%) compared to other post types whichpresented higher degrees of marginal gap formation:titanium post at 11%, zirconia post at 16.5%, andstainless steel post at 17.4%Dietschi D, Ardu S, Rossier-Gerber A, Krejci I. Adaptation of adhesive post and cores to dentin after in vitro occlusal loading: evaluation of post material influence. J Adhes Dent 2006; 8:
32 B) GatesGlidden drills A) a flame heated endo plugger,B) GatesGlidden drillsC) GPX drills
33 sixty-six extracted maxillary central Removed from CEJAh26Six teeth were used as positive and negative controlother sixty teeth were divided into 3 groups, each group containing 20 teethapical dye leakage in each group was measured by astereomicroscope
34 Minimal mean dye leakage was related to the hot plugger group Maximum mean leakage was observed in Gates glidden drill group
35 Kwan and Harrington (1981) and Madison and Zakariasen (1984) found that post space preparation with Gates Glidden drills immediately after obturation actually decreased the amount of apical leakage.
36 Flame-heated endo pluggers FastInexpensivedon‘t cause canal shape alterationsBurn potential for the dentist, dental assistant or the patientdid not cause any permanent damage to theperiodontium
37 Peeso reamers Very fast Creates parallel walls which provide optimal retention form for the postpossiblity of creating root perforation, canal transportation, overenlargement of the canalOnly in straight canals
38 The gates glidden drills are more conservative instruments compared with Peeso reamers drills
39 GPX match standardized endothontic file sizes # 25 #50. Slight frictional heat which softens the GP before removalFast and effectiveThe bur does not engage the dentin so canal shape remains unaltered and the frictional heat generated is minimal