Smear layer removal by passive ultrasonic irrigation and 2 new mechanical methods for activation of the chelating solution

Impact of different agitation methods on smear layer cleaning of mesial canals with accentuated curvature

Objectives

This study evaluated the impact of different methods of irrigant agitation on smear layer removal in the apical third of curved mesial canals of 3 dimensionally (D) printed mandibular molars.

Materials and Methods

Sixty 3D-printed mandibular second molars were used, presenting a 70° curvature and a Vertucci type II configuration in the mesial root. A round cavity was cut 2 mm from the apex using a trephine of 2 mm in diameter, 60 bovine dentin disks were made, and a smear layer was formed. The dentin disks had the adaptation checked in the apical third of the teeth with wax. The dentin disks were evaluated in environmental scanning electron microscope before and after the following irrigant agitation methods: G1(PIK Ultrasonic Tip), G2 (Passive Ultrasonic Irrigation with Irrisonic- PUI), G3 (Easy Clean), G4 (HBW Ultrasonic Tip), G5 (Ultramint X Ultrasonic tip), and G6 (conventional irrigation-CI) (n = 10). All groups were irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid.

Results

All dentin disks were 100% covered by the smear layer before treatment, and all groups significantly reduced the percentage of the smear layer after treatment. After the irrigation protocols, the Ultra-X group showed the lowest coverage percentage, statistically differing from the conventional, PIK, and HBW groups (p < 0.05). There was no significant difference among Ultramint X, PUI-Irrisonic, and Easy Clean (p > 0.05). None of the agitation methods could remove the smear layer altogether.

Conclusions

Ultramint X resulted in the most significant number of completely clean specimens.

Cleaning and disinfection of the root canal system provided by four active supplementary irrigation methods

This in vitro study evaluated the bacterial reduction provided by the EndoActivator (EA), Easy Clean (EC), passive ultrasonic irrigation (PUI), and XP-Endo Finisher. Eight-four mesial roots of mandibular first molars were instrumented, inoculated with Enterococcus faecalis, and divided into four groups (n. 20). Bacterial reduction in the main canals and dentinal tubules were respectively determined by MTT assays and Live/Dead BackLight technique through confocal laser scanning microscopy (CLSM) at 50, 100, and 150 µm in-depth (n. 10 per group). Statistical analyses were conducted following a significance level of 95% (P < 0.05). A significant statistical difference was just identified between XPF and EC in the main canals. In the dentinal tubules from the main root canals, at 100 and 150 µm in-depths, significant statistical differences were only observed between XPF and EC (P = 0.027) for the former and between XPF and EC (P = 0.011) and XPF and PUI (P = 0.021) for the latter. In the dentinal tubules from the isthmus, at 100 µm in-depth, statistically relevant differences did occur between XPF and EC (P = 0.038) and EC and EA (P = 0.029). At 150 µm in-depth, these differences were only significant by comparing XPF and PUI (P = 0.025) and XPF and EC (P = 0.036). Although no irrigation method could thoroughly disinfect the RCS, bacterial reduction indexes were generally better after using XPF.

Influence of agitation methods of irrigants after methylene blue-mediated PDT on the bonding interface of a fiber post cementation system

BACKGROUND

This study evaluated the effects of final agitation methods of irrigants to remove methylene blue and sodium hypochlorite residues after PDT-assisted endodontic treatment on the bond strength of fiber posts cemented with etch-and-rinse adhesive and conventional resin cement.

METHODS

Ninety bovine teeth were endodontically treated. In sequence, post space preparation followed by methylene blue-mediated PDT and sodium hypochlorite (NaOCl) irrigation were performed. Six final irrigations protocols for dye and NaOCl removal were performed prior to cementation with etch-and-rinse adhesive (Adper Scocthbond Multipurpose) and conventional dual resin cement (RelyX ARC): Conventional endodontic irrigation (CEI), passive ultrasonic irrigation (PUI), mechanical agitation with XP Endo Finisher (XPF), XP Clean (XPC) or Easy Clean (ECL) and distilled water (NCO - control). After fiber post cementation, push-out bond strength test was performed at different thirds of the post space. Failure mode was also analyzed. ANOVA and Tukey's post-hoc test was used for data analysis (α=5%).

RESULTS

PUI, XPF e XPC protocols showed the highest bond strength values with no difference among them (p > 0.05), although they were similar to NCO, regardless of the post space third. CEI e ECL showed similar bond strength values, regardless of the third (p > 0.05). Adhesive failure was the most incident for CEI and ECL, while mixed and cohesive failures were predominant in PUI, XPF, XPC and NCO groups.

CONCLUSIONS

Mechanical agitation of distilled water with XPF, XPC and PUI after methylene blue-mediated PDT and irrigation with 2.5% sodium hypochlorite promoted bond strength of the resin cementation system in post space dentin comparable to control group.