Evaluation of push out bond strength of fiber post after treating post space with 2 different techniques
Creators: name: Iswarya Raju
name: Sreedev Chundangaparambil Pushpahasan
name: Sebeena Mathew
Publisher: name: F1000Research
Year: 2017

description: Introduction: Endodontically treated teeth lose physiologic vascularization; thereby losing water and reduction of collagen cross-linking. Post-endodontic treatments with posts are essential for the retention of the coronal restoration, though they do not increase the mechanical properties of the roots. Fauchard introduced first wooden dowel post in 1746 since then variety of posts like metal, ceramic, fiber post has evolved. Fiber posts have gained popularity because of its esthetic appearance and Young’s modulus of elasticity similar to that of dental tissue. Affective adhesive bonding between post and root canal dentin improves the distribution of forces at dentin-post interface, eventually called as Tertiary monoblock. This eliminates the unfavorable vertical root fracture. Different types of fiber posts are available like epoxy resin posts reinforced with carbon fibers, epoxy resin or dimethacrylate posts reinforced with quartz or glass fibers, Zirconia posts and posts reinforced with polyethylene fibers. Moreover this resin-polymerized matrix makes them noncorrosive. Luting relies on hybrid layer formation into dentin, which depends on dentinal surface treatment. It improves resin tag formation between adhesive materials and intertubular dentin . <br><br>The major disadvantage of fiber post is debonding from post space. Mainly debonding takes place between luting material and dentin. This can be due to smear layer, affects of irrigant, cement residue, polymerization shrinkage, unfavorable C factor, type of dentin and presence of pulp tissue remnants.As now the adhesive cementation lies on resin dentin interdiffusion zone and resin tags <br><br>Chemical irrigants play a major role in successful debridement of root canals during shaping and cleaning procedures. Several factors affect the amount of debris on post space such as technique used in removal of gutta-percha, sealer and type of instrument used. Many irrigants are used to remove the heavy smear layer produced in the post space. Sodium hypochlorite (NaOCl) the `gold standard’ among irrigants has properties of dissolving the organic substances, neutralize the toxic substances. NaOCl on removing the organic substance leaves behind oxidized dentin, which inhibits the adhesion of resin cements to dentin by preventing polymerization. Ethylenediaminetetraaceticacid (EDTA) removes the inorganic components and produces wide opened dentinal tubules, which improves the adhesion of resin cement to the dentin.<br><br>Now a days use of laser for root canal debridement along with other chemical irrigants have proved to be effective. Among the laser systems diode laser has gained importance due to its compactness and low cost. Diode lasers have wavelength within the infrared range, have bactericidal properties and ability to remove smear layer. Commonly used diode laser wavelengths are 810 nm and 980 nm, which have flexible fibers making it suitable for endodontic use. <br><br>Literature search showed no studies comparing the effect of diode laser and hypochlorite, EDTA on post space. Hence push out bond strength of fiber post was planned to evaluate after treating the post space with diode laser and NaOCl, EDTA in the present study. Two hypothesis were tested there is significance in post space irrigation technique on bond strength of fiber post and use of diode laser would not enhance the bond strength.<br><br>Aim : The present short study aimed to evaluate the push out bond strength of the fiber post after treating the post space with Hypochlorite EDTA and Diode Laser .<br>Samples preparation :Total of 15 root canal treated decorated samples were taken ,post space prepared leaving 5mm at the apex , the samples were divided into 3 groups ,group 1 saline control ,group 2  post spaces were treated with sodium hypochlorite 5% and EDTA 17 % for 1 minute and  group 3 with diode laser of 890 nm in pulsed mode 1.5 watts for 1 minute .samples were dried and fiber posts were luted using dual cure cements.  Samples were cut horizontally and evaluated under universal testing machine with a cross head speed of 1 mm per minute . Then these samples were viewed under stereo microscope for finding the failure mode .Statastical analysis were done using  One way anova and Tukeys multiple variance test.<br><br>Result: NaOCl and EDTA  group showed better results than diode laser group . 73 % of mixed failures were observed <br>Discussion : The better result for EDTA group can be because of the ca chelation and it stays helps the monomer to penetrate into the dentinal tubules and hence high bond strength. Whereas Diode laser melts the dentinal tubules preventing resin tag formation .