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john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Sun Nov 20, 2005 2:53 pm    Post subject: Posts Reply with quote

Gen Dent. 2004 Mar-Apr;52(2):143-6.


Effect of no ferrule on failure of teeth restored with bonded posts and cores.

Ng CC, al-Bayat MI, Dumbrigue HB, Griggs JA, Wakefield CW.

Department of General Dentistry, Texas A&M University System Health Science Center, Baylor College of Dentistry, Dallas, USA.

This study investigated how the absence of a ferrule affected the failure load of teeth that had been restored with bonded fiber posts and resin cores. There was a significant difference (p < 0.001) between the ferrule and nonferrule groups' load to failure. For the ferrule group, root fracture was the predominant mode of failure; in the nonferrule group, debonding failures were predominant.
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john kanca



Joined: 14 May 2005
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PostPosted: Sun Nov 20, 2005 2:54 pm    Post subject: Reply with quote

J Prosthet Dent. 2005 Oct;94(4):321-9.


Finite element analysis of stresses in endodontically treated, dowel-restored teeth.

Asmussen E, Peutzfeldt A, Sahafi A.

Department of Dental Materials, Faculty of Health Sciences, School of Dentistry, University of Copenhagen, 20 Norre Alle, DK-2200 Copenhagen N, Denmark. ea@odont.ku.dk

STATEMENT OF PROBLEM: Endodontically-treated, dowel-restored teeth may experience fracture, but investigations of variables related to fracture are often inconclusive and occasionally contradictory. PURPOSE: The finite element method was used to analyze the stresses in dowel-restored teeth. The variables studied were material, shape, bonding, modulus of elasticity, diameter, and length of the dowel. MATERIAL AND METHODS: The model of the dowel-restored tooth involved dentin, ligament, cortical and trabecular bone, gingiva, and gutta-percha. The dowels were made of glass fiber, titanium, or zirconia and modeled as an approximation of the brands ParaPost Fiber White, ParaPost XH, and Cerapost, respectively. The dowel was cemented with zinc-phosphate cement or with bonded or nonbonded resin luting agents, and an approximation of the material properties of these 2 materials were used in the modeling. The restoration included a composite resin core and a gold crown. Other variables included taper versus parallel-sided posts, modulus of elasticity, diameter, and length of post. The model was axisymmetrical in 3 dimensions. A load of 100 N was applied to the crown at an angle of 45 degrees, and tensile, shear, and von Mises stresses were calculated. RESULTS: The generated stresses decreased with respect to the dowel material in the following order: glass fiber, titanium, and zirconia. Stresses were in general higher with tapered than with parallel-sided dowels. Stresses were reduced by bonding and with an increasing modulus of elasticity, increasing diameter, and increasing length of the dowel. CONCLUSIONS: Within the limitations of this study, it was found that all investigated dowel-related factors influenced the stress field generated in dowel-restored teeth.
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john kanca



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PostPosted: Sun Nov 20, 2005 4:40 pm    Post subject: Reply with quote

Clin Oral Investig. 2005 Jun;9(2):84-90. Epub 2005 Mar 4. Related Articles, Links


Resistance to cyclic loading of teeth restored with posts.

Sahafi A, Peutzfeldt A, Ravnholt G, Asmussen E, Gotfredsen K.

Department of Prosthetic Dentistry, School of Dentistry, University of Copenhagen, Norre Alle 20, DK-2200 , Copenhagen N, Denmark. ars@odont.ku.dk

This in vitro study evaluated the effect of presence of post, presence of core, and of shape, type, and surface treatment of posts on resistance to cyclic loading of crowned human teeth. For all teeth, crowns designed without ferrule were cast in sterling silver and luted with resin cement (Panavia F). Each tooth underwent cyclic loading of 600 N at two loads per second until failure. Teeth that had only been crowned showed significantly higher resistance to cyclic loading than teeth with cores or with post and cores. No significant differences were found between teeth restored with cores only or with post and cores, irrespective of surface-treatment of the posts. Teeth restored with parallel-sided cast post (ParaPost XP) and cores showed significantly higher resistance to cyclic loading than teeth with either tapered cast posts or untreated prefabricated posts of titanium alloy (ParaPost XH) or glass fiber composite (ParaPost Fiber White). No significant difference was found between teeth restored with parallel-sided cast post and cores and teeth restored with untreated prefabricated posts of zirconia (Cerapost). Surface treatment of posts significantly increased the resistance to cyclic loading compared with untreated posts. When posts are used, surface treatment is recommended.
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john kanca



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PostPosted: Sun Nov 20, 2005 4:42 pm    Post subject: Reply with quote

J Prosthet Dent. 2005 Jan;93(1):45-50. Related Articles, Links


Fatigue resistance of endodontically treated teeth restored with three dowel-and-core systems.

Goto Y, Nicholls JI, Phillips KM, Junge T.

University of Washington, Seattle, WA, USA. ygoto@usc.edu

STATEMENT OF PROBLEM: The successful restoration of endodontically treated teeth is enhanced by a crown design employing the ferrule effect. However, it is unclear which dowel-and-core system most effectively supports successful treatment. PURPOSE: The purpose of this study was to compare the load fatigue resistance of 3 dowel-and-core systems. MATERIAL AND METHODS: Fifteen endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 1.5 mm incisal to the cemento-enamel junction (CEJ). At the level of the CEJ, specimens were then prepared for crowns with 1-mm complete shoulder finish lines and 1.5 mm of axial wall height. The prepared teeth were divided into 3 groups (n=5) and restored with 1 of the following dowel-and-core combinations: Group CG, cast gold dowels and cores; Group TA, titanium alloy dowels (ParaPost XH) with composite cores; or Group FR, fiber-reinforced resin dowels (ParaPost FiberWhite) with composite cores. A dentin bonding agent (OptiBond Solo) was placed prior to the composite cores. Dowel-and-core castings and titanium alloy dowels were cemented with zinc phosphate cement. The fiber-reinforced dowels were cemented with a resin cement (ParaPost Cement). The crowns for all specimens were cast with an incisal notch for applying the fatigue load. The independent variable measured was the number of load fatigue cycles required to cause luting cement failure. The data were subjected to 1-way analysis of variance and the Student-Newman-Keuls test for 3 subsets (alpha=.05). RESULTS: The mean value+/-standard deviation for the cycles to failure for each group was: Group CG: 11,897+/-4080 load cycles, Group TA: 24,384+/-8231 load cycles, and Group FR: 50,696+/-7063 load cycles. Significant differences were found between all groups ( P<.05). CONCLUSIONS: Fiber-reinforced resin dowels and bonded composite cores under fatigue loading provided significantly stronger crown retention than cast gold dowels and cores and titanium alloy dowels with composite cores under fatigue loading.
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john kanca



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PostPosted: Sun Nov 20, 2005 4:51 pm    Post subject: Reply with quote

Quintessence Int. 2003 Mar;34(3):199-201. Related Articles, Links


A comparison of the retention of tooth-colored posts.

Qualtrough AJ, Chandler NP, Purton DG.

Unit of Operative Dentistry and Endodontology, University Dental Hospital of Manchester, Manchester, United Kingdom. alison.qualtrough@man.ac.uk

OBJECTIVE: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using titanium posts as controls. METHOD AND MATERIALS: Sixty recently extracted single-rooted, caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of 10 for post preparation. Post space preparation was carried out according to the individual manufacturer's instructions. All posts were bonded using Panavia F. A 4-mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a cross-head speed of 5 mm/min were recorded. RESULTS: It was found that the parallel-sided Lightposts were significantly more retentive than all of the other posts. Parapost Fibrewhite posts were more retentive than tapered Lightposts and Snowposts. There was no significant difference between the retention of stainless steel Paraposts and any of the other groups. CONCLUSIONS: Serrated parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. When all groups were considered, post dimension appeared to influence retention, with parallel-sided posts being more retentive than tapered posts.
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john kanca



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PostPosted: Mon Nov 21, 2005 11:17 am    Post subject: Reply with quote

I am convinced that parallel-sided posts are the best choice. It seems to show that way consistently in the literature.
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Kirk Blanchard



Joined: 24 May 2005
Posts: 138
Location: Halifax Canada

PostPosted: Mon Nov 21, 2005 12:26 pm    Post subject: Reply with quote

I was introduced to a post a few years ago that seems to offer the best of both worlds. It's the Optipost. The design is a series of decreasing diameter cylinders. The logic is that this is a parallel sided system, yet the apical portion isn't as wide as the coronal. I've since stopped stocking the pre-fab posts, but I still use the prep-burs to make this shape for my cast post/cores.

The idea makes a lot of sense to me. Does the literature bear this out?

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john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Mon Nov 21, 2005 12:30 pm    Post subject: Reply with quote

I have not used it and I have seen nothing of it in the literature but it looks to me as though an awful lot of tooth structure is removed during its placement.
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Kirk Blanchard



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Location: Halifax Canada

PostPosted: Mon Nov 21, 2005 12:40 pm    Post subject: Reply with quote

There are different burs for different teeth. I never use the fat one pictured. I use one that was set for a bicuspid or a lateral incisor. There's much less dentin removed.
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