Salameh Ziad, Sorrentino Roberto, Ounsi Hani F, Goracci Cecilia, Tashkandi Esam, Tay Franklin R, Ferrari Marco
Department of Prosthetic Dental Sciences, King Saud University, Riyadh, Saudi Arabia.
J Endod. 2007 Jul;33(7):848-51. doi: 10.1016/j.joen.2007.01.017. Epub 2007 Mar 26.
Endodontically treated teeth are traditionally restored with a crown to prevent fracture. The aim of this study was to compare the fracture resistance and failure modes of endodontically treated maxillary premolars treated with or without a fiber post and restored with different types of crowns. Eighty human maxillary premolars were selected. After root canal treatment, the teeth were embedded in resin blocks and divided into four groups. Samples received MOD cavity preparations and were divided into two subgroups: with and without fiber posts and restored using porcelain fused to metal, lithium disilicate, fiber-reinforced composite, or zirconia crowns. The specimens were vertically loaded in the central fossa using a universal loading machine until failure, and the maximum breaking loads were recorded. Samples were perfused with Indian ink to highlight the fracture lines and the mode of failure that was classified as restorable or nonrestorable. Even without post, all crown designs resisted vertically applied forces beyond those that may be encountered in the mouth. Two-way analysis of variance revealed the use of a fiber post (p = 0.007) and the type of crown (p < 0.001) significantly affected the restorability of fractured teeth. The relationship between placing or not placing the post and the type of failure (restorable/nonrestorable) was found to be significant (chi(2) test, p = 0.002). Although post placement resulted in higher fracture resistance values, these were significant for Empress II crowns only. The results suggest that the posts could contribute to the reinforcement and strengthening of pulpless maxillary premolars. With respect to failure modes, placement of fiber posts improved the fracture from nonrestorable to restorable patterns. This study suggests that the placement of fiber posts is necessary to improve fracture resistance even under full-coverage crowns.
传统上，根管治疗后的牙齿会用牙冠修复以防止折断。本研究的目的是比较经根管治疗的上颌前磨牙在使用或不使用纤维桩并采用不同类型牙冠修复后的抗折性和失败模式。选取了80颗人类上颌前磨牙。根管治疗后，将牙齿嵌入树脂块中并分为四组。样本进行了MOD洞形预备，并分为两个亚组：有纤维桩和无纤维桩，分别使用金属烤瓷冠、二硅酸锂冠、纤维增强复合材料冠或氧化锆冠进行修复。使用万能加载机在中央窝垂直加载样本直至失败，并记录最大破坏载荷。样本用印度墨水灌注以突出骨折线和失败模式，失败模式分为可修复或不可修复。即使没有桩，所有牙冠设计都能抵抗垂直施加的力，超过口腔中可能遇到的力。双向方差分析显示，使用纤维桩（p = 0.007）和牙冠类型（p < 0.001）对折断牙齿的可修复性有显著影响。发现是否放置桩与失败类型（可修复/不可修复）之间的关系具有显著性（卡方检验，p = 0.002）。虽然放置桩导致更高的抗折性值，但仅对Empress II冠具有显著性。结果表明，桩可以有助于增强无髓上颌前磨牙的强度。关于失败模式，纤维桩的放置将骨折模式从不可修复改善为可修复。本研究表明，即使在全冠修复下，放置纤维桩对于提高抗折性也是必要的。
