Effect of post‐space treatment on retention of fiber posts in different root regions using two self‐etching systems

Fiber posts, in combination with resin cements, havebeen widely used to restore endodontically treated teeth.The retention of fiber posts in roots is dependent uponthe adhesion between the resin cement and the dentin, aswell as on the adhesion between the resin cement andposts. However, the adhesion between resin and dentin isconsidered to be a weak point in luting a fiber post (1, 2).Scanning electron microscopy (SEM) analysis (3) hasshown that dentin walls after post preparation are cov-ered by a heavy smear layer containing rough debris andremnants of gutta-percha and sealer, which may interferewith effective bonding to dentin. Therefore, post-spacetreatments that effectively remove the smear layer andimprove the retention of the fiber post are of clinicalinterest.Etching, chemical irrigation, and ultrasonic treatmenthave been reported to be effective in the removal of thesmear layer on endodontically treated dentin (4–8).Chemical irrigants, such as solutions of sodium hypo-chlorite (NaOCl), or EDTA in combination with NaOCl,have been used in previous studies to clean the post space(9–12). However, some studies have reported a negativeeffect of NaOCl irrigation on the adhesion of resincement to intraradicular dentin (13–16). NaOCl breaksdown into sodium chloride and oxygen. It is thought thatthe liberation of oxygen may inhibit the polymerizationof resinous bonding materials and interfere with resininfiltration into the demineralized dentin (13–16).Therefore, the effect of chemical irrigation on theretention of fiber posts remains uncertain. Bondstrengths of fiber posts to different root regions usingvarious luting systems have been investigated, and, ingeneral, the bond strength in the apical region of a postspace is relatively lower than in the coronal region (17,18). In view of the difficulties experienced regardingaccess of instruments and chemical solutions to theapical root region, it is desirable to evaluate the effect ofpost-space treatment on the retention of a fiber post indifferent root regions.Various total-etching or self-etching systems areavailable for bonding to intraradicular dentin. It is wellknown that a wet-bonding technique is essential for atotal-etching system to achieve optimal bond strength(19). However, control of surface wetness is difficult toachieve in the deep and narrow post space within a rootcanal. The use of self-etching systems has recently beenproposed for the cementation of fiber posts (11, 20).Because self-etching systems can be used on both wet anddry dentin, the problem associated with the moistapplication technique can be eliminated. Furthermore, it