Preparation Prerequisites for Effective Irrigation of Apical Root Canal: A Critical Review

Comparative Analysis of AH Plus Bond Strength to Root Canal Dentin and Adhesive Interface Quality after Calcium Hydroxide Removal using Different Irrigation Protocols

INTRODUCTION

To evaluate the push-out bond strength (POBS) of AH Plus sealer to root dentin and the adhesive interface quality after calcium hydroxide (Ca(OH)2) intracanal dressing removal with different final irrigation protocols.

METHOD

After root canal instrumentation and irrigation, 40 root canals were filled with Ca(OH)2 and sealed. After 14 days, the specimens were randomly distributed according to the irrigation protocols for Ca(OH)2 removal (n = 10): GH2O (control) - distilled water; GNaOCl - 1% NaOCl; GEDTA - 17% EDTA; GEDTA + NaOCl - 17% EDTA + 1% NaOCl. The root canals were filled with AH Plus sealer and gutta-percha. After 7 days, the roots were sectioned into dentin slices and submitted to POBS test and analysis of the adhesive interface under scanning electron microscope. The POBS data were statistically evaluated (analysis of variance and Tukey test). The Kruskal-Wallis and Mann-Whitney tests were used to analyze the adhesive interface (α = 0.05).

RESULTS

GH2O, GNaOCl, and GEDTA + NaOCl had similar POBS values, with higher values on the apical third, in comparison with other thirds (P < .05). A homogeneous and free-of-gaps adhesive interface was observed for GH2O, GNaOCl, and GEDTA + NaOCl, with difference between GH2O and GEDTA (P < .05). GH2O and GEDTA + NaOCl presented higher sealer tags formation (P < .05).

CONCLUSION

The final rinse with EDTA for Ca(OH)2 dressing removal had a negative effect on the POBS of the filling material to root dentin. The use of EDTA followed by NaOCl had results similar to the distilled water, providing uniform and free-of-gaps adhesive interface, and a higher number of sealer tags.

Effect of the Irrigation Agitation Technique on Postoperative Pain in Teeth With Symptomatic Irreversible Pulpitis

Introduction Irrigation of the root canal system is a vital step in endodontic treatment aimed at disinfecting the canal. The efficacy of irrigation can be improved by various irrigation agitation methods. One such novel method of interest is the manual dynamic agitation (MDA) technique. However, the effect of MDA on postoperative pain as compared to needle irrigation (NI) with sodium hypochlorite has been scarcely explored. This study aimed to compare the effects of NI and MDA techniques on postoperative pain in teeth with symptomatic irreversible pulpitis. Materials and methods This quasi-experimental study was conducted at the Department of Operative and Paediatric Dentistry, Fauji Foundation Dental Hospital, over four months after gaining ethical approval. One hundred and sixty-eight participants diagnosed with symptomatic irreversible pulpitis were enrolled in the study through the purposive sampling technique. The participants were divided into two groups based on the irrigation technique used: Group A (NI) and Group B (MDA). Postoperative pain was recorded after six hours, 24 hours, 48 hours, and seven days using the 0-100mm visual analog scale (VAS). The VAS scores were compared using an independent sample t-test. Results Out of 168 participants, 48.2% were in Group A and 51.2% in Group B. The study found that VAS pain scores for Group B (MDA) were significantly lower at six hours, 24 hours, 48 hours, and seven days as compared to Group A (NI), with a p-value less than 0.001. Conclusion This study shows that the MDA technique leads to decreased postoperative pain both immediately after endodontic treatment and a week later as compared to the NI technique. Hence, the use of MDA can aid in controlling postendodontic pain and, therefore, ensure smoother recovery and increased patient satisfaction.

Effect of Photodynamic Therapy on the Pushout Bond Strength of Resin-Based and Calcium Silicate-Based Endodontic Sealers

Introduction: This study aimed to assess the effect of photodynamic therapy (PDT) on the pushout bond strength (PBS) of resin-based and calcium silicate-based endodontic sealers. Methods: Forty single-canal teeth were assigned to four groups. After root canal preparation by the crown-down technique and smear layer removal, groups 1 and 2 served as the control group, and groups 3 and 4 underwent PDT by using a low-level diode laser as the light source and methylene blue as the photosensitizer (MB). The root canals in groups 1 and 3 were filled with AH26 sealer while the root canals in groups 2 and 4 were filled with Endoseal TCS. The samples were sectioned at 4, 8, and 12 mm from the apex tip (1mm thick slices). The PBS test was performed, and the mode of failure was determined in the coronal, middle, and apical thirds. The data were analyzed by the Kruskal-Wallis, Friedman, and Dunn tests. Results: No significant difference was noted in the PBS of resin-based and calcium silicate-based sealers in the apical, middle, or coronal thirds in the application of PDT (P>0.05). The PBS of AH26 was significantly higher than that of Endoseal TCS (P<0.05). Cohesive failure was the dominant mode of failure in the AH26 groups, while mixed failure was the dominant failure mode in the Endoseal TCS groups. Conclusion: PDT had no significant effect on the PBS of resin-based and calcium silicate-based sealers.

Comparison of the Effect of Three Irrigation Techniques and Root Canal Preparation Size on Sodium Hypochlorite Penetration into Root Canal Dentinal Tubules

Objective

This study aims to compare the effects of conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), and innovative sonic-powered irrigation (EDDY) on the penetration of sodium hypochlorite (NaOCl) solutions into root canal dentinal tubules at different levels of the root canal.

Materials and Methods

One hundred ninety-two extracted first mandibular premolars of 17- to 25-year-old patients were decoronated 13 mm from the root apices and separated into two groups according to apical preparation sizes (APS) 25 and 40. The root canals were dried with a paper point and stained in crystal violet for 72 hours. Each APS group was separated into three groups according to irrigation techniques, as follows: CSI, PUI, and EDDY. Roots were perpendicularly resected to the long axis at three levels (coronal, middle, and apical). Photomicrographs were taken of all three cross-sections of each tooth under a stereomicroscope. The depth of the bleached zone was measured with ImageJ software. The data were analyzed by Welch's analysis of variance and an independent t-test (p = 0.05).

Results

No penetration was found at the apical level in the CSI25, CSI40, and PUI25 groups. The EDDY25 and EDDY40 groups showed the most significant penetration at the middle and apical levels compared to the other groups (p < 0.05).

Conclusions

Within the limitations of this study, irrigation techniques and APS affect the penetration depth of NaOCl into the root canal dentinal tubules. In terms of irrigation techniques, the penetration was deepest when EDDY was used, followed by PUI and CSI. In terms of APS, NaOCl penetrated deeper into APS40 than APS25. The use of the EDDY irrigation technique in APS25 can improve the penetration of NaOCl into root canal dentinal tubules at the apical level.

[The influence of endodontic rinsing liquids activation methods on the root dentin structure and effectiveness of root canal cleaning]

The study was aimed to conduct a morphological assessment of the influence exerted by a certain method of activation of endodontic rinsing liquid on the root dentin structure and canal cleaning effectiveness in an ex vivo experiment. The study was performed on 20 single-rooted teeth removed due to complicated caries in people aged 25-44 years. A devised method of vacuum-jet irrigation was used to carry out the final antiseptic treatment and to activate a rinsing liquid in the group No. 1 (n=10), and an endodontic syringe with ultrasonic activation was used in the group No. 2 (n=10). Optical and scanning electron microscopy data were used to assess dentin histostructure, presence or absence of organic inclusions in the root canal lumens, quality of preparation and contour lines of their sides. An analysis of scans demonstrates that the vacuum-jet irrigation method effectively cleans the root canal lumen in the apical area in 90% of the cases, while irrigation with an endodontic syringe and ultrasound activation has been effective in 67% of the cases. The smear layer throughout the root canals in the samples of the group No. 1 was removed in 100% of the cases. At the same time, the smear layer in the canal apical area was not completely removed in either of the samples of the group No. 2. An analysis of photomicrographs of histotopographic cross sections of the dental roots in group No. 2 under consideration revealed numerous cavities in the circumpulpal dentin, which form nidi of destruction up to 10-15 mcr in diameter merging in the cervical and middle third of the root. At the same time, a typical structure of the circumpulpal dentin with a well-developed network of dentinal tubules and intact peritubular and intertubular matrix was observed throughout the dental roots in the samples of the group No. 1. These investigational studies allow us to conclude that vacuum-jet irrigation of root canals provides better cleaning, completely removes the smear layer and does not damage the root dentin structure.

Dentin tubule orientation determines odontoblastic differentiation in vitro: A morphological study

Odontoblasts are post-mitotic cells responsible for maintenance of the dentin, and are therefore important for dental health. In some cases, irreversible pulpitis leads to necrosis and consequently death of odontoblasts. Regenerative endodontics (RE) uses the concept of tissue engineering to restore the root canals to a healthy state, allowing for continued development of the root and surrounding tissue. Human dental pulp stem cells (hDPSCs) have been successfully used in RE to restore odontoblast function. Surface microgeometry is one of the most important factors involved in the induction of differentiation of hDPSCs into odontoblast-like cells. Although different authors have demonstrated the importance of a dentin-like surface with accessible dentin tubules to induce differentiation of hDPSCs, the ultrastructural characteristics of the cells and the secreted extracellular matrix have not been studied in depth. Here, we used an acellular dentin scaffold containing dentin tubules in different spatial geometries, which regulated their accessibility to cells. hDPSCs were cultured on the scaffolds for up to 6 weeks. Systematic characterization of differentiated cells was performed using both optical (hematoxylin and eosin, Masson trichrome, and immunohistochemical determination of dentin sialoprotein [DSSP]) and transmission electron microscopy. The results presented here indicated that cells grown on the dentin surface containing accessible dentin tubules developed a characteristic odontoblastic phenotype, with cellular processes similar to native odontoblasts. The cell organization and characteristics of secreted extracellular matrix were also similar to those of native dentin tissue. Cells grown on non-accessible dentin tubule surfaces secreted a more abundant and dense extracellular matrix, and developed a different phenotype consisting of secretory flat cells organized in layers. Cells grown far from the scaffold, i.e., directly on the culture well surface, developed a secretory phenotype probably influenced by biochemical factors released by the dentin scaffold or differentiated cells. The results presented here support the use of hDPSCs to regenerate dentin and show the utility of scaffold microgeometry for determining the differentiation and secretory phenotype of cultured cells.

Microbiota in the apical root canal system of tooth with apical periodontitis

Background

Apical periodontitis (AP) is essentially an inflammatory disease of microbial etiology primarily caused by infection of the pulp and root canal system. Variation of the bacterial communities caused by AP, as well as their changes responding to dental therapy, are of utmost importance to understand the pathogensis of the apical periodontitis and establishing effective antimicrobial therapeutic strategies. This study aims to uncover the composition and diversity of microbiota associated to the root apex to identify the relevant bacteria highly involved in AP, with the consideration of root apex samples from the infected teeth (with/without root canal treatment), healthy teeth as well as the healthy oral.

Methods

Four groups of specimens are considered, the apical part of root from diseased teeth with and without root canal treatment, and wisdom teeth extracted to avoid being impacted (tooth healthy control), as well as an additional healthy oral control from biofilm of the buccal mucosa. DNA was extracted from these specimens and the microbiome was examined through focusing on the V3-V4 hypervariable region of the 16S rRNA gene using sequencing on Illumina MiSeq platform. Composition and diversity of the bacterial community were tested for individual samples, and between-group comparisons were done through differential analysis to identify the significant changes.

Results

We observed reduced community richness and diversity in microbiota samples from diseased teeth compared to healthy controls. Through differential analysis between AP teeth and healthy teeth, we identified 49 OTUs significantly down-regulated as well as 40 up-regulated OTUs for AP.

Conclusion

This study provides a global view of the microbial community of the AP associated cohorts, and revealed that AP involved not only bacteria accumulated with a high abundance, but also those significantly reduced ones due to microbial infection.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5474-y) contains supplementary material, which is available to authorized users.