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Öğe Bond Strength Between Root Dentin and Three Glass-Fiber Post Systems(Mosby-Elsevier, 2006) Kalkan, Mustafa; Üşümez, Aslıhan; Öztürk, A. Nilgün; Belli, Sema; Eskitaşcıoğlu, GürcanStatement of problem. Glass-fiber posts were introduced for use after endodontic therapy instead of metal alloy and ceramic posts. There are several new types of glass-fiber post systems available, but little is known about how well these posts bond to the root surface. Purpose. The purpose of this in vitro study was to compare the bond strengths of 3 different types of glass-fiber post systerns-opaque, translucent, and electrical glass-in 3 different locations of prepared post spaces. Material and methods. Sixty human intact single-rooted extracted teeth were used. The root canals were prepared using a step-back technique and obturated with gutta-percha using lateral condensation. The roots were divided into 3 experimental groups and further divided into 2 subgroups according to testing time (n = 10). Roots were restored with 1 of the following post systems according to the manufacturer's instructions: opaque glass-fiber posts (Snowpost), translucent glass-fiber posts (FiberMaster), and electrical glass-fiber posts (Everstick). A self-etching primer (Clearfil Liner Bond) was applied to the walls of the post spaces, allowed to etch for 30 seconds, and gently air dried. A dual-polymerized bonding agent (Clearfil Liner Bond, Bond A and B) was then applied to the same walls. A dual-polymerizing resin luring agent (Panavia F) was mixed for 20 seconds and then placed in the post spaces using a lentulo spiral instrument. The roots were placed in light-protected cylinders; then the light source was placed directly on the flat cervical tooth surfaces and the cement was polymerized. Specimens were stored in light-proof boxes for 24 hours or 1 week after the polymerization procedure. Each root was cut horizontally, and six 1-mm-thick root segments (2 apical, 2 middle, and 2 cervical) were prepared. Using a push-out test, the bond strength between post and dentin was measured after 24 hours or I week using a universal testing machine. Statistical analysis was performed with 3-way ANOVA followed by independent t tests (alpha = .05) to detect differences between groups defined by the specific interacting variables. The different combinations of posts and luting material from the cervical segments were analyzed with SEM. Results. The 3-way ANOVA indicated that push-out test values varied significantly according to the post system used (opaque, electrical, and translucent) (P < .01); the root segments (cervical, middle, and apical) (P < .01), however, did not vary statistically according to the time of testing (24 hours and 1 week). Opaque and electrical glass-fiber posts showed higher bond strength values than translucent posts (P < .01). Push-out bond strength values of cervical segments were significantly higher than the middle and apical segments in translucent and electrical glass-fiber post groups (P < .01). In the opaque glass-fiber post group, there were no significant differences between cervical and middle segments. In SEM analysis, a distinct hybrid zone with long, numerous resin tags located between luting material and dentin was exhibited in all post systems. Conclusion. The opaque and electrical glass-fiber posts exhibited similar bond strengths, and translucent posts exhibited the lowest bond strength. The highest bond strength was observed in the cervical third of the post spaces for translucent and electrical glass-fiber post groups.Öğe Effect of Dentin Bonding and Ferrule Preparation on the Fracture Strength of Crowned Teeth Restored With Dowels and Amalgam Cores(Mosby-Elsevier, 2006) Aykent, Filiz; Kalkan, Mustafa; Yücel, Münir Tolga; Özyeşil, Atilla GökhanStatement of problem. It is necessary to obtain an adequate bond at the core/dentin junction where the majority of failures occur. The effect of recently developed dentin bonding agents on the fracture resistance of endodontically treated teeth at the amalgam core/dentin junction is unclear. Purpose. The Purpose of this study, was to evaluate the effects of 2 dentin bonding agents and a ferrule preparation on the fracture resistance of crowned mandibular premolars incorporating prefabricated dowel and silver amalgam cores. Material and methods. Sixty extracted mandibular second premolars were divided into 6 groups of 10 each. The coronal portion of each tooth was removed at the cemento-enamel junction (CEJ) in the first 3 groups. In the other groups, teeth were sectioned 1 nun above the CEJ to create a ferrule. After root canal preparations, prefabricated dowels (ParaPost) were placed. The first group served as a control and was tested without application of bonding agents and without incorporation of a ferrule design. In the second and third groups, respectively, an autopolymerizing adhesive (Superbond D-Liner) and a dual-polymerizing adhesive (Panavia F) were applied to tooth surfaces before restorative procedures. For the fourth (ferrule) group, no bonding agent was applied, but a 1-mm ferrule preparation was used. In the fifth (ferrule+D-Liner) and sixth (ferrule+Panavia F) groups, respectively, autopolymerizing and dual-polymerizing bonding agents were used in conjunction with the ferrule preparation. After amalgam core fabrication, Ni-Cr full cast crowns for each group were prepared and cemented. All specimens were stored in water for I week and thermal cycled 1000 times between 5 degrees and 55 degrees C. A compressive shear load was applied at an angle of 135 degrees to the crown, and the maximum load at fracture (N) was recorded. The data were analyzed with 1-way ANOVA and Tukey Honestly Significant Difference tests (alpha=.05). Results. Significantly higher fracture strength values were demonstrated for the ferrule+Panavia F (652.5 N), ferrule+D-liner (649.1 N) and ferrule (592.4 N) groups, respectively, than for the other groups. The next highest fracture strength values were found for the D-Liner (485.0 N) and Panavia F (486.3 N) groups. The control group (376.6 N) demonstrated the lowest fracture strength in all test groups (P<.001). Conclusion. A ferrule preparation or a bonding agent designed for silver amalgam core-dentin bonding can each increase the fracture strength for teeth receiving cast crowns after endodontic therapy and dowel and amalgam core restorations.Öğe Evaluation of Two Post Core Systems Using Two Different Methods (Fracture Strength Test and a Finite Elemental Stress Analysis)(Lippincott Williams & Wilkins, 2002) Eskitaşcıoğlu, Gürcan; Belli, Sema; Kalkan, MustafaThe aim of this study was to compare a fiber composite laminate (FCL) post core and a conventional cast post core system by using two different methods. The first method was a conventional fracture strength test, and the second was a finite elemental stress-analysis method (FEM). For the conventional fracture strength test, 20 extracted, human upper, central incisors were used. The teeth were decoronated, treated endodontically, and restored with two post core systems. After embedding the samples in resin blocks, a loading force was applied to the teeth at a crosshead speed of 5 mm/min at an angle of 45 degrees to the long axis of the tooth. The data were recorded, and the results were compared by using the Mann-Whitney U test. There was no statistically significant difference between the two post systems (p > 0.05). For FEM analysis, a pseudo three-dimensional model of a maxillary central incisor, theoretically restored with either a cast post or an FCL, was used. The analysis was performed by using the structural analysis program (SAP90). FEM analysis showed that stress was accumulated within the cast post core system, and transmission of stress to supportive structures and the tooth was low. This is an advantage for tooth and supporting tissues. When the FCL post core system was evaluated by FEM, the results indicated that this system transferred stress to supportive structures and the tooth while stress accumulation within the post system was low. This is an advantage for the restoration but disadvantage for the supporting tissues.Öğe Replacing an anterior, metal-ceramic restoration with an all-ceramic resin-bonded fixed partial denture: A case report(QUINTESSENCE PUBLISHING CO INC, 2006) Ozyesil, Atilla Gokhan; Kalkan, MustafaSince the first resin-bonded fixed partial denture was described, this adhesive technique for splinting mobile teeth has developed into a conservative method for replacing missing teeth. Heat-pressed all-ceramic materials have been introduced for the fabrication of 3-unit fixed partial dentures in the anterior and premolar region. This clinical report describes the replacement of a conventional partial coverage metal-ceramic resin-bonded fixed partial denture with an all-ceramic resin-bonded fixed partial denture in the anterior maxillary area.
