Restoration of vertically fractured teeth by adhesion and replantation

概要

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A vertically-fractured tooth may be restored by adhesion of the fractured fragments with resin cement. We did an in vitro investigation of the factors influencing the prognosis of restored vertically-fractured teeth. The two fragments of each tooth were bonded together with resin cement, and the micro-tensile bond strength was measured after trimming them to a dumbbell shape. A metal post was placed in the root canal of each tooth the force applied to the post that was necessary to fracture the tooth was measured. In another test, the two fragments of the fractured root were bonded together with resin cement, and either a metal or a resin post was placed in the canal. We then measured the force applied to the post that was necessary to break the bond of the adhered fragments. We found that when a fractured root is bonded with resin cement, the bond strength weakens as the cement layer becomes thicker. The methyl methacrylate (MMA) resins Super Bond C & B and Multi bond II acted as a buffer and prevented refracture when stress parallel with the tooth axis was exerted on the post. No difference was observed in the risk of refracture among post materials when they are not bonded to the tooth. The resistance of roots reconstructed by adhesion to stress parallel with the tooth axis less than 25% that of the intact root.