Comparison of the time required for removal of intraradicular cast posts using two Brazilian ultrasound devices

Abstract

The aim of this in vitro study was to compare the time required for removal of intraradicular cast posts cemented with zinc phosphate (ZF) or glass ionomer cement (GIC), using two Brazilian ultrasound devices (BUD). Seventy two human inferior premolars with single root canals were sectioned transversally at the cementoenamel junction. In each specimen, the root canal was endodontically treated, the post space was prepared to a depth of 9 mm and the canal was molded to obtain a post impression. After the casting procedures, the posts were randomly distributed into 2 groups (n = 36) according to the luting material used: G1 - ZF and G2 - GIC. The tooth and luted post set was then embedded in an acrylic resin block. The groups were then divided into 3 subgroups (n = 12) according to the ultrasound device used: A - Enac (Osada Electric, Japan), used as a control group; B - Profi II Ceramic (Dabi Atlante, Brazil) and C - Jet Sonic Satelec (Gnatus, Brazil). The posts were submitted to the vibration process with maximum power set on all surrounding surfaces. Time of application was recorded with a chronometer until complete post dislodgment, and the data were analyzed by the ANOVA test (p < 0.05). The averages required for post removal in G1 and G2 were respectively 41.42 and 92.03 seconds, with significant statistical difference (p = 0.001). No statistical difference was observed among the three ultrasound devices (p = 0.088), and the BUD presented a performance similar to that of the international gold standard device (Enac). Moreover, the type of luting agent had a greater influence on the time required for post removal than the origin of the ultrasonic unit.

Comparison of Different Ultrasonic Tip Angulations on Time Required for Cast Post Removal

“…Although in vitro tests are not always able to reproduce in vivo conditions, they can offer comparative values that may guide clinical procedures. 18 When an ultrasonic device is used for post removal, the vibration is transferred to the cement line by the post. Thus, the vibration is expected to cause the cement to fracture and facilitate the post removal procedure.…”

“…19 Several factors may interfere in the ultrasonic efficiency, such as the type of luting agent, length, form, diameter and type of post and post adaptation to the root canal walls. 8,17,18,20,21 The efficacy of ultrasound is related to the intensity and movement of the vibration, the manner in which the tip is applied on the core and the type of tip used. …”

“…26 The results of the present study showed that all the cast posts were successfully removed in a short time interval (mean time up to 2 minutes). Variations from 2 to 16 minutes 15,16,18,27,28 in vibration time necessary to dislodge the posts can be attributed to experimental design differences. 17 In the present study, an effort was made to maximize the energy transfer from the instrument tip to the post, evaluating the angle and the position of the tip in relation to the post, according other authors.…”

“…17 Several studies have reported that the type of luting agent can have an influence on the ultrasonic efficiency for post removal. 8,16,18 Zinc phosphate cement was used in this study, because it is the main material used to lute cast posts and cores with a satisfactory performance. 11,29 In this study, all the cast posts were removed in short periods of time.…”

Influence of ultrasound, with and without water spray cooling, on removal of posts cemented with resin or glass ionomer cements: An in-vitro study

“…Several authors have suggested the use of ultrasound alone or in combination with other techniques to make this procedure safer. [3–7]…”