Post retention: The effect of sequence of post-space preparation, cementation time, and different sealers

Many endodontic sealers contain constituents that have been shown to inhibi t the polymerization of resin cements. This may be important when prefabric ated posts are cemented at the same appointment as root canal obturation. T his study evaluated the effects of cementing posts with a resin cement imme diately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space pr eparation was also assessed as a critical variable. One hundred twenty extr acted canines were randomly divided into eight experimental groups. The var iables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. Al l teeth received a stainless steel #6 Parapost XP cemented with a resin cem ent, Panavia 21. Each experimental group underwent tensile testing for rete ntion using an Instron universal testing machine. For both sealers posts ce mented in teeth in which the canal was obturated before post-space preparat ion and thus had sealer-contaminated dentin removed by the space preparatio n procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sea ler used and time of cementation had no specific effect on retention. Achie ving a clean, "freshened" dentinal surface during mechanical post-space pre paration seems to be a critical variable for post retention when a resin ce ment is used.