Ultrasonic preparation and obturation of root‐end cavities

Abstract

This study evaluated the preparation of root-end cavities using an ultrasonically activated file, and the obturation of such cavities. In the first part, the root canals of 40 extracted teeth were prepared to size 40 and irrigated with NaOCl and EDTA. The root ends were resected and the teeth inoculated with Enterococcus faecalis, incubated for 10 days and divided into four groups: control; saline; irrigation; hand instrumentation performed via a retrograde approach up to size 50 using saline irrigant; ultrasonic instrumentation with prebent size 40 K-flex file inserted into a Piezon Master using saline irrigant. The teeth were fixed, sectioned longitudinally and viewed under scanning electron microscopy. Bacterial and smear layer scores were obtained at 1, 3, and 5 mm from the resected end. The bacterial scores for control and saline groups were similar; the scores for each instrumentation group were significantly lower than the control group (P<0.001). In addition, there were significantly fewer bacteria in the ultrasonic group compared with the hand instrument group (P<0.001). The smear layer scores for control and saline groups were similar, and significantly lower than in either instrumentation group (P<0.001). In the second part, root-end cavities were ultrasonically prepared in 20 extracted teeth. Ten cavities were filled with amalgam, and 10 with thermoplasticized gutta-percha and Grossman's sealer. After 24-h storage, the root ends were immersed in dye for 48 h. Cross-sectional slices of the obturated part of the root were evaluated using both light and confocal microscopy for dye leakage along the interface of filling material and dentine. There were no statistical differences between the leakage of amalgam and gutta-percha root-end fillings, nor between the two methods of microscopy.

Short‐term tissue response to potential root‐end filling materials in infected root canals

“…Wuchenich et al (1994) showed that root-end cavities prepared using ultrasonic tips were deeper, had parallel walls and followed the long axis of the root canal system compared with those prepared by burs. In another study, when retrograde instrumentation was carried out on teeth using an ultrasonically-activated file, it was reported that at the root end, there was a significant reduction in the quantity of bacteria, which had previously been inoculated (Sultan & Pitt Ford 1995). It may be argued that if ultrasound had been used, the results of this study might have been better.…”

Ultrasonics in Endodontics: A Review of the Literature

“…The cleaning effect and the cutting ability of ultrasonic retrotips have been described as satisfactory by many authors (222,223,233,237,249,250). Furthermore, US produced less smear layer in a retro-end cavity compared to a slow-speed handpiece (214,221,(233)(234)(235)251).…”

Evaluation of root‐end cavity preparation using ultrasonic retrotips

“…Ultrasonic retrotips have been developed as an alternative to the low‐speed handpiece for root‐end cavity preparation. Many reports have been written on the properties of ultrasonic retrotips (Gorman et al . 1995, Sultan & Pitt Ford 1995, Frank et al .…”