Evaluation of the effectiveness of GentleWave System and passive ultrasonic irrigation with minimally invasive and conventional instrumentation technique against Enterococcus faecalis lipoteichoic acid (LTA) in infected root canals

A promising approach utilising photothermal energy to disinfect the root canal system: An in vitro investigation

This study aimed to assess root canal disinfection through various irrigation protocols, including a novel photothermal system called 'LEAP'. Mandibular premolars were infected with Enterococcus faecalis and divided into five groups for different treatments: Group 1: standard needle irrigation; Group 2: passive ultrasonic irrigation; Group 3: GentleWave; Group 4: LEAP; and Group 5: Group 1 + Group 4. Microbial counts were measured before (S1) and after disinfection (S2) using colony-forming units (CFU) and confocal laser scanning microscopy (CLSM). Results revealed a significant reduction in bacterial counts for all groups (p < 0.05). While the percentage of dead bacteria near the canal wall (0-50 μm) did not differ significantly, at 50-150 μm, LEAP and SNI + LEAP exhibited significantly higher bacterial reduction than other groups (p < 0.05). The findings indicate that LEAP is comparable to existing irrigation devices in the main root canal and notably superior in tubular disinfection.

Efficacy of the GentleWave System in the removal of biofilm from the mesial roots of mandibular molars before and after minimal instrumentation: An ex vivo study

AIM

To compare the efficacy of Enterococcus faecalis biofilm removal using the GentleWave System (GWS) (Sonendo Inc, CA) on non-instrumented versus minimally instrumented root canal systems.

METHODOLOGY

Thirty-four mandibular molars were autoclaved and allocated to four groups: Negative control (n = 5); positive control (n = 5); Group 1: non-instrumentation + GWS (NI + GWS) (n = 12); and Group 2: minimal instrumentation + GWS (MI + GWS) (n = 12). Of 34 samples, 24 samples with Vertucci type 2 configuration within the mesial root of each sample were allocated to Groups 1 and 2 and then matched based on the working length and root canal configuration. After inoculation of samples with E. faecalis for 3 weeks, the GWS was used on Group 1 without any instrumentation and Group 2 after instrumentation of mesial canals until size 20/06v. CFU and SEM analysis were used.

RESULTS

Log10 (CFU/mL) from the positive control, and Group 1 and 2 were 7.41 ± 0.53, 3.41 ± 1.54, and 3.21 ± 1.54, respectively. Both groups showed a statistically significant difference in the reduction of viable E. faecalis cells compared to the positive control (Group 1 [p = .0001] and Group 2 [p < .0001]), whilst showing no significant difference between the two tested groups (p < .05).

CONCLUSION

The use of GWS on the non-instrumented root canal system could be an effective disinfection protocol in removing the biofilm without dentin debris formation.

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.

Comparison of conventional and contemporary root canal disinfection protocols against bacteria, lipoteichoic acid (LTA), and lipopolysaccharide (LPS)

This study devised a dual-species biofilm model to investigate bacteria, lipoteichoic acid (LTA), and lipopolysaccharide (LPS) simultaneously, and compared the efficacy of conventional and contemporary disinfection protocols. Seventy single-rooted mandibular premolars were included. Fourteen teeth were negative control, and 56 teeth were infected with 3-week-old E. faecalis and E. coli GFP biofilm. Fourteen/56 teeth were positive control, with seven teeth processed for CLSM analysis and seven teeth sampled with paper points (PPs) and cryogenically ground for bacterial, LTA, and LPS analyses. Forty-two teeth were randomly divided into three groups: GWS (GentleWave system) + MIT (minimally invasive technique), PUI (passive ultrasonic irrigation) + CIT (conventional instrumentation technique), and XP-EF (XP-endo Finisher) + CIT (All, n = 14). Samples were collected before (s1) and after disinfection (s2) with PPs and after cryogenically ground (s3). CFUs were counted, and LTA and LPS were quantified with LTA-ELISA and LAL assay, respectively. XP-EF was as effective as PUI (p > 0.05). GWS + MIT was the most effective disinfection protocol against bacteria, LTA, and LPS (p < 0.05). In conclusion, PUI, XP-EF, and GWS were highly effective against bacteria, LTA, and LPS, with GWS being the most effective.

Multispecies biofilm removal by a multisonic irrigation system in mandibular molars

AIM

The aim of the study was to assess biofilm removal efficacy of GentleWave System and passive ultrasonic irrigation (PUI).

METHODOLOGY

Twenty-two human mandibular molars with Vertucci's type II configuration in the mesial root were selected. Teeth were autoclaved, inoculated with dental plaque and incubated in a CDC biofilm reactor for two weeks. The mesial roots were instrumented up to 20.06 file (V-Taper) for the GentleWave group and up to 35.04 file (Vortex Blue) for PUI group. Irrigation was performed using GentleWave and PUI irrigation protocols (n = 11). Dentine debris on paper points samples were obtained for quantitative real-time polymerase chain reaction (qPCR) and 16S ribosomal RNA gene sequencing (next-generation aequencing-NGS). For qPCR, a non-parametric test (α = 0.05) was used. Next-generation sequencing data were analysed using mothur, with alpha diversity calculated as the Shannon and Chao1 indices and Bray-Curtis dissimilarities were used for beta diversity. Differences in alpha diversity and abundances of genera were evaluated using Kruskal-Wallis test. Differences in community composition were evaluated using analysis of similarity with Bonferroni correction for multiple comparisons.

RESULTS

Quantitative real-time polymerase chain reaction results showed that the reduction estimated in percentages for both groups was equivalent (p > .05). NGS analysis showed that both techniques promoted a significant reduction in reads and OTUs number (p < .05). Shannon alpha diversity and Chao1 index showed no differences between pre- or post-treatment samples for both groups (p > .05). Additionally, pre-treatment communities differed from post-treatment samples in both groups regarding bacterial taxa reduction (ANOSIM R = 0.50 and 0.55, p < .001).

CONCLUSIONS

Bacterial reduction in mesial roots of mandibular molars prepared to 35.04 with PUI was similar to those prepared to 20.06 with a multisonic irrigant activation system.