[In vitro evaluation of the effectiveness of XP-endo Finisher file on smear layer removal after root canal instrumentation]

Abstract

Objective: This study aimed to evaluate the effectiveness of XP-endo Finisher (XPF) file and passive ultrasonic irrigation (PUI) in the smear layer removal of the root canal.

Methods: A total of 60 human single-rooted premolars were selected and decoronated to standardize their canal length to 16 mm. Tooth samples were prepared using a S3 rotary system to prepare root canal with the file size of 3S and then randomly divided into 6 groups according to the final irrigation protocol, as follows: XPF 3 mL of 3% NaOCl for 1 min (group A); XPF 3 mL of 3% NaOCl for 1 min, followed by 4 mL of 17% ethylene diamine tetraacetic acid (EDTA) for 1 min (group B); PUI of 3 mL of 3% NaOCl for 1 min (group C); PUI of 3 mL of 3% NaOCl for 1 min, followed by 4 mL of 17% EDTA for 1 min (group D); 3 mL of 3% NaOCl for 1 min by using a syringe and a 30 G side-vented needle (group E); and 3 mL of 3% NaOCl for 1 min by using a syringe and a 30 G side-vented needle, followed by 4 mL of 17% EDTA for 1 min (group F). After the completion of the root canal preparation, the teeth were split into two longitudinally. The mean numbers of the visible open dentinal tubules in the apical and middle thirds of the root canals were evaluated via scanning electron microscope.

Results: The whole surfaces of the root canals in groups A, C, and E were covered by a smear layer. Groups A and C possessed significantly higher number of visible open dentinal tubules than in group E (P<0.05), with statistically insignificant difference between groups A and C (P>0.05). The apical third of the samples in groups B and D and in the middle thirds of canals in group F exhibited a small amount of smear layer, and the dentinal tubules were open or semi-open. The root canal surfaces in the apical third of the samples in group F were covered by a smear layer, and the dentinal tubules were sealed or semisealed. The smear layers in the middle third of the samples in groups B and D were removed, and the dentinal tubules were more visibly open than those of the four other groups (P<0.05). The difference between groups B and D were statistically insignificant (P>0.05).

Conclusions: The difference between XPF and PUI in terms of the smear layer removal of the root canals was insignificant. Hence, XPF, as a new irrigation agitation technique, can aid in improving smear layer removal.

Keywords: XP-endo Finisher file; passive ultrasonic irrigation; smear layer.

图 1. 牙本质小管开口数量的计算方法

Fig 1 The evaluation method of the number of open dentinal tubules

图 2. 6组根尖区和根中区根管壁形态 SEM × 500

Fig 2 The morphology of the middle 1/3 and apical 1/3 dentinal areas of 6 groups SEM × 500 A1：A组根尖区；A2：A组根中区；B1：B组根尖区；B2：B组根中区；C1：C组根尖区；C2：C组根中区；D1：D组根尖区；D2：D组根中区；E1：E组根尖区；E2：E组根中区；F1：F组根尖区；F2：F组根中区。