Materials Science Cement Distribution and Bond Strength in Cemented Posts

Abstract

Rods of lucite were drilled to receive a No. 5 parapost to a depth of 4 mm and 7 mm. Posts were fitted and cemented either by coating the post with cement or by placing the cement in the prepared hole with a lentulo spiral in a low-speed hand-piece and then inserting the pre-coated post. Photographs were taken to determine the distribution of the cement. The lentulo spiral distributed the cement along the entire length of the preparation, but coating alone did not distribute the cement evenly. The tensile strength with these two methods of post cementation was also compared in four groups of extracted teeth. In Groups IA and IIA, the post preparation was rinsed with 2 ml of 5.25% NaOCl and dried with paper points and blasts of air. In Group IA, the post was coated with zinc phosphate cement and seated. In Group IIA, the cement was placed into the post space with a lentulo spiral in a slowly rotating hand-piece; the post was then coated and seated. In Groups IB and IIB, the post preparation was rinsed with 1 ml of 17% Na2 EDTA followed by 1 ml of 5.25% NaOCl to remove the smeared layer at the dentin-cement interface. The posts were then cemented as in IA and IIA. Under the conditions of this experiment, the following conclusions can be drawn: Placing cement into the preparation with a lentulo spiral increased the tensile strength and the overall cement distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Post and core systems, refinements to tooth preparation and cementation

“…Cementation techniques include placing cement lute over the post and/or placing it in the post hole with a lentulo-spiral, paper point or an endodontic explorer. The most successful method was to place the cement into the post hole with a lentulo-spiral and coating the post before inserting 28,29 with a gentle pumping action to allow adequate venting of the post coronally. 30 If the cement is applied to the post alone a reduction in retention is observed.…”

Root canal posts — some prosthodontic aspects

“…Generally speaking, for rool canal posts mechanical failures will occur in the luting cement. The origin of such failures is generally to be found either in an improper handling of the cement (13,14) or in the factors dealt with in section I. They will therefore not be further diseussed here.…”

Cast post and core foundation for the badly broken down molar tooth

“…8 Indeed, as the posts are divergent, much shorter ones should provide adequate retention. Goldman et al 9 found posts cemented into properly conditioned post holes, where the smear layer has been removed, exhibit much higher retention, especially when the luting cement is introduced by a Lentulo spiral. The best method for removing the smear layer in their study was rinsing with 17 per cent ethylenediamine tetra acetic acid (EDTA) followed by 5.2 per cent sodium hypochlorite.…”