Histomicrobiologic aspects of the root canal system and periapical lesions in dogs' teeth after rotary instrumentation and intracanal dressing with Ca(OH)2 pastes

The Essential Role of 17-Octadecynoic Acid in the Pathogenesis of Periapical Abscesses

INTRODUCTION

Periapical abscesses are 1 of the most frequent pathologic lesions in the alveolar bone. Recently, we have identified 17-octadecynoic acid (17-ODYA) as the highest unique metabolite in periapical abscesses. Therefore, the aim of this study was to investigate the immunologic and pathophysiological roles of this metabolite in the initiation and development of periapical abscesses.

METHODS

Periodontal ligament fibroblasts and peripheral blood mononuclear cells were treated with 17-ODYA. Gene expression analysis and interleukin (IL)-8 release were determined using quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Macrophage polarization and cytokine release were also determined using flow cytometry and Luminex bioassay (R&D Systems, Minneapolis, MN), respectively.

RESULTS

In periodontal ligament fibroblasts, 17-ODYA caused significant (P < .0001) up-regulation of IL-1α, IL-1β, IL-6, matrix metalloproteinase-1, and monocyte chemoattractant protein-1 at 10 μmol/L after 6 days of treatment and up-regulation of platelet-derived growth factor alpha and vascular endothelial growth factor alpha at all tested concentrations after 2 days of treatment. In peripheral blood mononuclear cells, 17-ODYA significantly increased the expression of IL-1α, IL-1β, IL-6, matrix metalloproteinase-1, and monocyte chemoattractant protein-1 at 10 μmol/L (P < .0001) and vascular endothelial growth factor alpha and platelet-derived growth factor alpha at 1 μmol/L 17-ODYA (P < .0001). 17-ODYA polarized macrophages toward a proinflammatory phenotype (M1) and suppressed the release of pro- and anti-inflammatory cytokines. 17-ODYA significantly enhanced the release of IL-8.

CONCLUSIONS

This study was the first to identify the pathologic role of 17-ODYA in the development of periapical abscesses. The results of this study are important in shedding light on the pathogenesis of periapical abscesses in relation to microbial metabolites.

Comparative Metabolomics Reveals the Microenvironment of Common T-Helper Cells and Differential Immune Cells Linked to Unique Periapical Lesions

Periapical abscesses, radicular cysts, and periapical granulomas are the most frequently identified pathological lesions in the alveolar bone. While little is known about the initiation and progression of these conditions, the metabolic environment and the related immunological behaviors were examined for the first time to model the development of each pathological condition. Metabolites were extracted from each lesion and profiled using gas chromatography-mass spectrometry in comparison with healthy pulp tissue. The metabolites were clustered and linked to their related immune cell fractions. Clusters I and J in the periapical abscess upregulated the expression of MMP-9, IL-8, CYP4F3, and VEGF, while clusters L and M were related to lipophagy and apoptosis in radicular cyst, and cluster P in periapical granuloma, which contains L-(+)-lactic acid and ethylene glycol, was related to granuloma formation. Oleic acid, 17-octadecynoic acid, 1-nonadecene, and L-(+)-lactic acid were significantly the highest unique metabolites in healthy pulp tissue, periapical abscess, radicular cyst, and periapical granuloma, respectively. The correlated enriched metabolic pathways were identified, and the related active genes were predicted. Glutamatergic synapse (16–20),-hydroxyeicosatetraenoic acids, lipophagy, and retinoid X receptor coupled with vitamin D receptor were the most significantly enriched pathways in healthy control, abscess, cyst, and granuloma, respectively. Compared with the healthy control, significant upregulation in the gene expression of CYP4F3, VEGF, IL-8, TLR2 (P < 0.0001), and MMP-9 (P < 0.001) was found in the abscesses. While IL-12A was significantly upregulated in cysts (P < 0.01), IL-17A represents the highest significantly upregulated gene in granulomas (P < 0.0001). From the predicted active genes, CIBERSORT suggested the presence of natural killer cells, dendritic cells, pro-inflammatory M1 macrophages, and anti-inflammatory M2 macrophages in different proportions. In addition, the single nucleotide polymorphisms related to IL-10, IL-12A, and IL-17D genes were shown to be associated with periapical lesions and other oral lesions. Collectively, the unique metabolism and related immune response shape up an environment that initiates and maintains the existence and progression of these oral lesions, suggesting an important role in diagnosis and effective targeted therapy.

Prevalence of unculturable bacteria in the periapical abscess: A systematic review and meta-analysis

OBJECTIVE

To assess the prevalence of unculturable bacteria in periapical abscess, radicular cyst, and periapical granuloma.

METHODS

PubMed, Scopus, Science Direct, and Ovid databases were systematically searched from January 1990 to May 2020. All the included studies were cross-sectional design. The risk of bias was assessed using Joanna Briggs Institute check-list. Heterogeneity was described using meta-regression and mixed-effects model for lesion, country, and sequence technique moderators. Funnel plot and unweighted Egger's regression test were used to estimate the publication bias. Microbiome data on diversity, abundance, and frequency of unculturable bacteria in the periapical lesions were reviewed, analysed, and the principal component analysis (PCA) was performed.

RESULTS

A total of 13 studies out of 14,780, were selected for the final analysis. These studies focused on the prevalence of unculturable bacteria in periapical abscesses and related lesions. Approximately 13% (95% CI: 7-23%) of the cumulative number of bacteria derived from periapical abscesses was unculturable. Country moderator significantly (P = 0.05) affects the diversity summary proportion. While the pooled frequency of unculturable bacteria was 8%; 95% CI: 5, 14%, the estimate of the pooled abundance of unculturable bacteria was 5%; 95% CI: 2, 12% with a significant (P = 0.05) country moderator that affects the abundance summary proportion. Of the 62 unculturable bacteria, 35 were subjected to PCA and Peptostreptococcus sp. oral clone CK035 was the most abundant species in periapical abscesses. Hybridization techniques were found to be the most reliable molecular methods in detecting the abundance and frequency of unculturable bacteria.

CONCLUSION

The significant prevalence of unculturable bacteria in the periapical abscess, suggests that they are likely to play, a yet unknown, critical role in the pathogenesis and progression of the disease. Further research remains to be done to confirm their specific contributions in the virulence and disease progression.

Quaternary ammonium silane, calcium and phosphorus-loaded PLGA submicron particles against Enterococcus faecalis infection of teeth: An in vitro and in vivo study

Refractory root canal infection of human teeth is the primary cause of dental treatment failure. Enterococcus faecalis is the major cause of refractory root canal infection. In the present study, poly(D,L-lactic-co-glycolide) (PLGA) submicron particles were used as carriers to deliver an antimicrobial quaternary ammonium silane (code-named K21) as well as calcium and phosphorus elements. The release profiles, antibacterial ability against E. faecalis, extent of infiltration into dentinal tubules, biocompatibility and in vitro mineralization potential of the particles were investigated. In addition, the antimicrobial effects of the particles against E. faecalis infection were evaluated in vivo in the teeth of beagle dogs. The encapsulated components were released from the PLGA particles in a sustained-release manner. The particles also displayed good biocompatibility, in vitro mineralization ability and antibacterial activity against E. faecalis. The particles could be driven into dentinal tubules of dentin slices by ultrasonic activation and inhibited E. faecalis colonization. In the root canals of beagle dogs, PLGA submicron particles loaded with K21, calcium and phosphorus demonstrated strong preventive effects against E. faecalis infection. The system may be developed into a new intracanal disinfectant for root canal treatment.

Pattern of Disinfection of Root Canal Dentin by Alternated Acid-Base Irrigating Regimen

Objective

To quantify Enterococcus faecalis density in root canal dentin after chemomechanical preparation (CMP) using alternated irrigating regimen.

Methodology

Root canals (RC) were contaminated with E. faecalis (ATCC 19433) for 3 weeks and evident biofilms were obtained. After initial sampling (S1), the CMP was aided by irrigants: saline solution (control; n=12), a conventional regimen (CR) (group 1; n=12) using 5.25% NaOCl and a final rinse with 17% EDTA, and an alternating regimen (AR) of intercalated use of NaOCl and EDTA (group 2, n=12), followed by a second sampling (S2). After 2 weeks, S3 was obtained. Two roots were analyzed by scanning electron microscopy. Each root was divided into cervical, mild, and apical segments and sampling of the superficial (n=90) and deep (n=90) dentin layers was obtained using Gates-Glidden burs. The E. faecalis density (CFU/mg) in log₁₀ was categorized as residual (0 > 0.2), moderate (0.2 ≥ 0.5), or elevated (> 0.5). The prevalence of positive samples in BHI and BHI-A was analyzed by Pearson's chi-square test. The data were normalized by a log₁₀ transformation of CFU and were analyzed by one-way ANOVA and Tukey's tests.

Results

Biofilms were observed only in the control root canal walls. Topographically, the controls and CR showed similar distributions of E. faecalis in the dentin. Microbiologically positive root canals harbored much E. faecalis in the adjacent dentin (p < 0.05). Irrigating saline provided moderate density of E. faecalis in the dentin while CR and AR resulted in a residual density of microorganisms (p < 0.05).

Conclusions

The Enterococcus faecalis density in dentin was influenced by the irrigating regimen and the microbiological status of the root canal. The CMP aided by the alternating regimen interfered with the recolonization of the root canal and topographic distribution of Enterococcus in root dentin.

Periapical lesions of the jaws: a review of 104 cases in ibadan

BACKGROUND

Periapical lesions (PLs) occur as a result of pulpal inflammation and may rarely be seen in the absence of pulpal diseases. They are the most common pathological lesions affecting the alveolar bone.

OBJECTIVE

This study aims to describe the clinicopathological features of PLs of the jaws with emphasis on the two most common types.

METHODS

Histopathology records of PLs diagnosed from January 1990 to December 2012 at the Department of Oral Pathology, University College Hospital Ibadan, were examined and categorized into periapical cysts (PCs); periapical granuloma (PGs) and others. Clinical data and histopathological features of these PLs were reviewed and analyzed.

RESULTS

One hundred and four lesions met the criteria for this study and consisted of PGs with 71 (68.3%) cases and PCs with 31 (29.8%) cases and one case each of apical scar and pleomorphic adenoma. Age range of cases was 9 to 80 years (mean=35.6 ± 15.8years) with a peak at age group of 20-29 years. Females were more frequently affected with 51.9% of cases. PLs were most frequently diagnosed in the anterior maxillary region with 58 (56.9%) cases, while the most frequently involved tooth was the left maxillary central incisor with 23 (22.1%) cases.

CONCLUSION

Findings in this study are consistent with those of previous studies. It is important for all periapical pathological specimens to be submitted for histological examination to establish an accurate diagnosis and aid in the identification of sinister lesions that may present in the Periradicular region of teeth.

In vitro antimicrobial activity of auxiliary chemical substances and natural extracts on Candida albicans and Enterococcus faecalis in root canals

OBJECTIVE

The aim of this study was to evaluate the antimicrobial activity of auxiliary chemical substances and natural extracts on Candida albicans and Enterococcus faecalis inoculated in root canals.

MATERIAL AND METHODS

Seventy-two human tooth roots were contaminated with C. albicans and E. faecalis for 21 days. The groups were divided according to the auxiliary chemical substance into: G1) 2.5% sodium hypochlorite (NaOCl), G2) 2% chlorhexidine gel (CHX), G3) castor oil, G4) glycolic Aloe vera extract, G5) glycolic ginger extract, and G6) sterile saline (control). The samples of the root canal were collected at different intervals: confirmation collection, at 21 days after contamination; 1st collection, after instrumentation; and 2nd collection, seven days after instrumentation. Microbiological samples were grown in culture medium and incubated at 37°C for 48 hours.

RESULTS

The results were submitted to the Kruskal-Wallis and Dunn (5%) statistical tests. NaOCl and CHX completely eliminated the microorganisms of the root canals. Castor oil and ginger significantly reduced the number of CFU of the tested bacteria. Reduction of CFU/mL at the 1st and 2nd collections for groups G1, G2, G3 and G4 was greater in comparison to groups G5 and G6.

CONCLUSION

It was concluded that 2.5% sodium hypochlorite and 2% chlorhexidine gel were more effective in eliminating C. albicans and E. faecalis, followed by the castor oil and glycolic ginger extract. The Aloe vera extract showed no antimicrobial activity.

Cold plasma therapy of a tooth root canal infected with enterococcus faecalis biofilms in vitro

INTRODUCTION

Complete sterilization of an infected root canal is an important challenge in endodontic treatment. Traditional methods often cannot achieve high-efficiency sterilization because of the complexity of the root canal system. The objective of the study was to investigate in vitro the feasibility of using a cold plasma treatment of a root canal infected with Enterococcus faecalis biofilms.

METHODS

Seventy single-root teeth infected with E. faecalis biofilms were divided into 7 groups. Group 1 served as the negative control group (no treatment), and group 7 was the positive control group with teeth treated with calcium hydroxide intracanal medication for 7 days. Groups 2 to 6 included teeth treated by cold plasma for 2, 4, 6, 8, and 10 minutes, respectively. The disinfection of the E. faecalis biofilm was evaluated by colony-forming unit (CFU) counting. Scanning electron microscopy was used to evaluate the structural changes of the E. faecalis biofilm before and after plasma treatment. Confocal scanning laser microscopy was used to investigate the vitality of the microorganisms in the biofilm before and after plasma treatment.

RESULTS

A significant decrease in the number of CFUs was observed after prolonged cold plasma treatment (based on the statistical analysis of the teeth in groups 2-6). Compared with the positive control group, cold plasma treatment of 8 or 10 minutes (groups 5 and 6) had a significantly higher antimicrobial efficacy (P < .05). The scanning electron microscopic analysis showed that the bacteria membrane was ruptured, and the structure of the biofilm was fully destroyed by the plasma. Confocal scanning laser microscopic studies indicated that the plasma treatment induced E. faecalis death and destruction of the biofilm.

CONCLUSIONS

The cold plasma had a high efficiency in disinfecting the E. faecalis biofilms in in vitro dental root canal treatment.

Periapical repair in dog teeth: root canal adhesive filling by using the Resilon System

INTRODUCTION

New filling biomaterials with better physicochemical properties would create a favorable biologic environment for the healing of periapical tissues. The aim of this study was to evaluate periapical repair after biomechanical preparation and root filling with an adhesive system compared with the gold standard material (gutta-percha+sealer) in dog teeth.

METHODS

The pulp of 25 root canals was removed. The apical cementum layer was perforated, and the root canals were prepared up to size #60 K-file followed by step-back shaping with the #90 K-file and filled by the lateral condensation technique. In the experimental group (n=15), the Resilon System (Pentron Clinical Technologies, Wallingford, CT) was used. As a control material (n=10), gutta-percha cones and pulp canal sealer were used. After 60 days, the animals were killed, and 10 histologic parameters were evaluated. Differences among the groups were analyzed by using the Mann-Whitney and Fisher exact tests.

RESULTS

In radiographic and histologic evaluations, most fillings were slightly short of the apex. Progressive regenerative stages were observed; however, there was a reduced prevalence of biologic foraminal closure. No significant differences were observed between the 2 biomaterials with regard to any of the parameters evaluated (P>.05).

CONCLUSIONS

The Resilon System shows periapical biocompatibility equivalent to the gold standard material.

Antimicrobial activity of sodium hypochlorite associated with intracanal medication for Candida albicans and Enterococcus faecalis inoculated in root canals

Objective:

The purpose of this study was to evaluate the action of sodium hypochlorite (NaOCl) associated with an intracanal medication against Candida albicans and Enterococcus faecalis inoculated in root canals.

Material and Methods:

Thirty-six human single-rooted teeth with single root canals were used. The canals were contaminated with C. albicans and E. faecalis for 21 days and were then instrumented with 1% NaOCl. The roots were divided into 3 groups (n=12) according to the intracanal medication applied: calcium hydroxide paste, 2% chlorhexidine (CHX) gel, and 2% CHX gel associated with calcium hydroxide. The following collections were made from the root canals: a) initial sample (IS): 21 days after contamination (control), b) S1: after instrumentation, c) S2: 14 days after intracanal medication placement; S3: 7 days after intracanal medication removal. The results were analyzed statistically by the Kruskal-Wallis test at 5% significance level.

Results and Conclusions:

Both 1% NaOCl irrigation and the intracanal medications were effective in eliminating E. faecalis and C. albicans inoculated in root canals.

Endodontic re-treatment associated with the elimination of amalgam root-end filling through sinus tracts: a report of two cases

Two patients presented with complaints of recurrent drainage of purulent exudate from sinus tracts, inflammation and pain after endodontic re-treatment of the maxillary left (Case 1) and right (Case 2) lateral incisors. The periapical lesions persisted after apical curettage, apicectomy and root-end filling with silver amalgam. Radiographic examination exposed the poor quality of the endodontic treatments and the silver amalgam root-end fillings, which were associated with periapical radiolucent areas in both teeth. The sinus tract persisted after root canal cleaning and shaping, followed by a calcium hydroxide root canal dressing. The root-end fillings were periapically dislodged with endodontic K-files, and showed progressive displacement by sinus tracts up to elimination in the oral cavity. Follow ups of 42 and 65 months post procedure revealed clinical disappearance of the symptoms, sinus tracts and exudates, and radiographs revealed that the repair process of the periapical radiolucent areas was quite advanced.

Residual antibacterial activity of chlorhexidine digluconate and camphorated p-monochlorophenol in calcium hydroxide-based root canal dressings

The purpose of this study was to evaluate the residual antibacterial activity of several calcium hydroxide [Ca(OH)2]-based pastes, placed in root canals of dogs' teeth with induced chronic periapical lesions. Root canals were instrumented with the ProFile rotary system and filled with 4 pastes: G1 (n=16): Ca(OH)2 paste + anesthetic solution; G2 (n=20): Calen® paste + camphorated p-monochlorophenol (CMCP); G3 (n=18): Calen®; and G4 (n=18): Ca(OH)2 paste + 2% chlorhexidine digluconate. After 21 days, the pastes were removed with size 60 K-files and placed on Petri plates with agar inoculated with Micrococcus luteus ATCC 9341. Pastes that were not placed into root canals served as control. After pre-diffusion, incubation and optimization, the inhibition zones of bacterial growth were measured and analyzed by Mann-Whitney U test at 5% significance level. All pastes showed residual antibacterial activity. The control samples had larger halos (p<0.05). The mean residual antibacterial activity halos in G1, G2, G3 and G4 were 7.6; 10.4; 17.7 and 21.4 mm, respectively. The zones of bacterial growth of G4 were significantly larger than those of G1 and G2 (p<0.05). In conclusion, regardless of the vehicle and antiseptic, all Ca(OH)2-based pastes showed different degrees of measurable residual antibacterial activity. Furthermore, unlike CMCP, chlorhexidine increased significantly the antibacterial activity of Ca(OH)2.