PubMed · 295530
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J F Roulet. 1979. [Endodontic prophylaxis, pulp protection].. https://pubmed.ncbi.nlm.nih.gov/295530/
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This study measured the force required to displace four different endodontic posts (an experimental, Para-Post, Flexi-Post, and V Lock) when tensile, torsion, or compressive forces were applied. Extracted mandibular premolars were decoronated at the cementoenamel junction, the roots were divided into groups of similar size, and the pulpal tissue was removed. The canals were enlarged, cleaned, and filled with gutta percha. Post preparations were made, and the posts were cut and cemented into the post spaces with resin cement. The roots were notched with a separating disc and lowered into a metal tube filled with acrylic resin. Two Minim pins were placed into the coronal dentin paralleling the post. Composite resin cores were made around the coronal 4 mm of the posts and the two pins for 10 specimens from each group. The specimens were placed into a standardized fixture and a load applied until failure. The tensile load required to pull the experimental post and resin was significantly less than the load required to remove the threaded posts. Flexi-Posts provided the greatest resistance to torsion and tensile loading. The compressive load required to fracture the core over the V-Lock post was significantly greater than the other post systems.
This study was performed on a newly developed sealing cement, TS60, to evaluate its physical properties, namely sealing, setting time, compressive strength, solubility and ease of removal. It was compared with Temporary Stopping (GC Dental Industrial Corp., Tokyo, Japan), Eugedain (zinc oxide-eugenol based material, Showa Yakuhin Kako Co. Ltd, Tokyo, Japan) and Cavit-G (calcium sulphate based material, Espe Gmbh, Seefeld, Germany), which are typical commercially available sealing cements. The results of the study revealed that TS60 had excellent sealing properties, good compressive strength, low solubility, and was readily removable by heating and melting.
Stress relaxation of four temporary restoratives was studied. In the vicinity of ambient mouth temperature, the relaxation characteristics of an unmodified zinc oxide-eugenol cement were more favorable than those of IRM and Cavit. The plastic behavior of gutta-percha temporary stopping precluded assessment of its relaxation at temperatures in excess of 22 degrees C.