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  • Scipioni et al and Chiapasco et al

    2018-11-15

    Scipioni et al. [21] and Chiapasco et al. [34] recommended that the periosteum should not be stripped off the labial plate in order not to affect the blood supply and to allow rapid revascularization of the expanded plate of bone. The periosteum has another function in treating the mal-fractures that might occur during the splitting procedure in which it prevents any cracked segment from dislodging and maintains the blood supply. Sub-periosteal reflection at the future sites of the bony cuts (tunneling), is a modification of the split thickness flap reflection, leaving the periosteum intact in the remainder of the bone plate, Some clinicians who perform the splitting technique with delayed implant placement prefer to do a full thickness flap prior to making the corticotomies (at the first surgery) and then perform a partial thickness flap during the second surgery for implant placement in order to reduce the bone resorption [35,36].
    Conclusion
    Introduction When fiber posts were first introduced they gained great popularity as their elastic modulus matches that of resin cements and dentin. This is considered to be advantageous for improving the performance of restorations and for decreasing the possibility of root fractures [1,2]. However, despite their cited advantages, the mismatch between the diameter of the post space and the prefabricated fiber post presented a clinical problem [3,4]. Prefabricated posts do not fit well into both non circular canals [5] and excessively flared canals resulting from carious extension, trauma, pulpal pathosis, or iatrogenic misadventure [3]. In such cases, if the post does not fit well, the layer of resin cement might be excessively thick, favoring the formation of air bubbles and hence predisposing to post debonding [6]. One of the proposed solutions for this problem is to reline the fiber post with resin composite [7]. Customizing the post increases its haspin inhibitor to the root walls and reduces the thickness of the resin cement layer [6]. Post retention depends on the intimate contact between the post and the root canal as well as on the bonding potential of the cement to the canal walls. Improving the contact between the post and the canal walls by relining may reduce the dependence on the bonding potential of the cement for retention [8]. It has been shown that cements with lower bonding potential but other favorable mechanical properties perform well in luting relined fiber posts [9]. Consequently; the main goal of fiber post relining was to reduce the thickness of the resin cement layer. Thin layers of cement present fewer defects as bubbles and voids than thick ones. The presence of these defects within the material act as crack raisers and decreases post retention [3,6]. Relining will therefore reduce the possibility of cohesive failures within the cement layer. In addition to relining, the cement type affects post retention. The use of cements with proper mechanical properties is essential for adequate post retention. Many types of cements were suggested to successfully lute fiber posts. Dual-cured resin cement generates higher bond strength to dentin than other cements [10]. However, its high polymerization shrinkage and the resulting stresses could impair the bonding to root dentin [11]. On the other hand self-adhesive resin cements appear to have low shrinkage because of their viscoelastic properties, leading to better intimate contact of the resin cement with the root canal walls and higher frictional resistance [12]. Moreover, when Bonfante et al. [13] studied the tensile bond strength of glass fiber posts luted with different cements, resin-modified glass ionomer cement exhibited lower bond strength values than resin cements. The authors attributed selective breeding to the fact that the mechanical properties of this cement are poorer compared with the resin cements [10]. The choice of resin cements that rely on the use of etch and rinse adhesives has been shown to achieve higher interfacial strengths in post spaces when compared with those utilizing mild self-etching adhesives or self-etching resin cement [14–16]. That was verified by Wang et al. [17] who studied bond strengths of an epoxy resin-based fiber post with four adhesive systems and concluded that the type of adhesive system and root region had a significant influence on the bond strengths of adhesively luted fiber posts. Total-etching technique achieved better bond strength than did the self-etching technique.