PRIASE 2021 guidelines for reporting animal studies in Endodontology: a consensus-based development

Gut microbiota dysbiosis links chronic apical periodontitis to liver fibrosis in nonalcoholic fatty liver disease: Insights from a mouse model

AIM

In this study, we investigated the systemic implications of chronic apical periodontitis (CAP). CAP may contribute to the nonalcoholic fatty liver disease (NAFLD) progression through the gut microbiota and its metabolites, which are related to the degree of fibrosis.

METHODOLOGY

Sixteen 7-week-old male apolipoprotein E knockout (apoE-/-) mice were randomly divided into two groups: the CAP and Con groups. A CAP model was established by sealing the first- and second-maxillary molars with bacterium-containing cotton balls. Apical lesions were evaluated by micro-CT. Histological evaluations of NAFLD were performed using second harmonic generation/two-photon excitation fluorescence (SHG/TPEF) assays. Additionally, we comprehensively analyzed the gut microbiota using 16S rRNA gene sequencing and explored metabolic profiles by liquid chromatography-mass spectrometry (LC-MS). Immunofluorescence analysis was used to examine the impact of CAP on tight junction proteins and mucin expression. Transcriptome assays have elucidated gene expression alterations in liver tissues.

RESULTS

Micro-CT scans revealed an evident periapical bone loss in the CAP group, and the total collagen percentage was increased (Con, 0.0361 ± 0.00510%, CAP, 0.0589 ± 0.00731%, p < .05). 16S rRNA sequencing revealed reduced diversity and distinct taxonomic enrichment in the CAP group. Metabolomic assessments revealed that differentially enriched metabolites, including D-galactosamine, were enriched and that 16-hydroxyhexadecanoic acid and 3-methylindole were depleted in the CAP group. Immunofluorescence analyses revealed disruptions in tight junction proteins and mucin production, indicating intestinal barrier integrity disruption. Liver transcriptome analysis revealed upregulation of Lpin-1 expression in the CAP group.

CONCLUSION

This study provides comprehensive evidence of the systemic effects of CAP on liver fibrosis in NAFLD patients by elucidating alterations in the gut microbiota composition and metabolism.

Inflammatory response to bioceramic and epoxy resin-based endodontic sealers implanted in mice subcutaneous tissue: An in vivo study

To evaluate the inflammatory tissue response to BioRoot™ RCS (BR) and AH Plus Jet (AHPJ) sealers implanted in mice subcutaneous tissue. It was hypothesized that the inflammatory tissue response to BR would be milder than to AHPJ. An in vivo study was carried out using isogenic mice. The sealers were implanted during standardized surgical procedures. The inflammatory response was evaluated by microscopic analysis and von Kossa reaction in the reactionary tissue around the specimens after 7, 21, and 63 days. For comparisons, a zinc oxide and eugenol sealer (ZOE) was used as a positive control, in addition to a negative control without a sealer (n = 10 per group/period). All statistical analyses considered a significance level of 5%. All endodontic sealers triggered an inflammatory tissue response after 7 days. BR had a higher inflammatory cell count and a thicker fibrous capsule when compared with AHPJ, but both were less inflammatory than ZOE (p < .001). After 21 days, BR continued to trigger an intense inflammatory tissue response, higher in both microscopic parameters compared to AHPJ, and a thicker fibrous capsule than ZOE (p < .001). After 63 days, the inflammatory tissue response decreased in BR, matching the fibrous capsule thickness with AHPJ and ZOE. BR promoted intense calcium precipitation in all study periods. After 63 days, AHPJ and BR sealers were more biocompatible to subcutaneous mice tissue, but AHPJ present better early inflammatory response, as well as BR showed potential bioactivity. RESEARCH HIGHLIGHTS: The inflammatory tissue response triggered by a bioceramic endodontic sealer (BR) was not milder than that triggered by an epoxy-resin based endodontic sealer (AHPJ) during the first 3 weeks, considering the microscopic analysis of the reactionary tissue.

PRIDASE 2024 guidelines for reporting diagnostic accuracy studies in endodontics: Explanation and elaboration

The Preferred Reporting Items for Diagnostic Accuracy Studies in Endodontics (PRIDASE) 2024 guidelines are based on the Standards for Reporting of Diagnostic Accuracy Studies (STARD) 2015 guidelines and the Clinical and Laboratory Images in Publications (CLIP) principles, with the addition of items specifically related to endodontics. The use of the PRIDASE 2024 guidelines by authors and their application by journals during the peer review process will reduce the possibility of bias and enhance the quality of future diagnostic accuracy studies. The PRIDASE 2024 guidelines consist of a checklist containing 11 domains and 66 individual items. The purpose of the current document is to provide an explanation for each item on the PRIDASE 2024 checklist, along with examples from the literature to help readers understand their importance and offer advice to those developing manuscripts. A link to the PRIDASE 2024 explanation and elaboration document is available on the Preferred Reporting Items for study Designs in Endodontology (PRIDE) website (https://pride-endodonticguidelines.org/pridase/) and on the International Endodontic Journal website (https://onlinelibrary.wiley.com/page/journal/13652591/homepage/pride-guidelines.htm).

27-Hydroxycholesterol contributes to hypercholesterolemia-associated aggravation of apical periodontitis in ovariectomized rats and raloxifene counteracts its action

AIM

The influence of hypercholesterolemia on the development of apical periodontitis (AP) is inconclusive. Recent studies revealed that cholesterol metabolite 27-hydoxycholesterol (27HC) can affect cellular responses to bacterial infections and oestrogen status and raloxifene may influence its action. Herein, we aimed to examine the impact of 27HC on production of inflammatory mediators by macrophages and the regulatory function of raloxifene. The contribution of 27HC to AP development and the therapeutic effect of raloxifene were evaluated in a rat model.

METHODS

Murine macrophages J774 cells were used. The expression of inducible nitric oxide synthase (iNOS) was examined by Western blot. The concentrations of C-C motif chemokine ligand (CCL) 2 and 27HC were assessed by enzyme-linked immunosorbent assay. Colorimetric assay was used to evaluate cholesterol levels. Experimental AP was induced in ovariectomized (OVX) or un-operated rats receiving high-fat/high-cholesterol diet (HFHCD) or normal diet (ND). Micro-computed tomography and immunohistochemistry were employed to evaluate disease severity and the therapeutic effect of raloxifene.

RESULTS

Cholesterol enhanced 27HC production in macrophages. 27HC induced iNOS and CCL2 synthesis by macrophages and estradiol suppressed the responses. In our animal model of AP, HFHCD plus OVX significantly augmented serum and lesion tissue levels of 27HC (p < .05 versus the ND group). Lesion size, infiltration of CD68+ cells, and iNOS+ monocytes were increased in parallel with 27HC accumulation. Raloxifene inhibited pro-inflammatory effects of 27HC on macrophages and suppressed AP progression in HFHCD/OVX rats (p < .05 versus the vehicle control group).

CONCLUSIONS

Our results suggested that 27HC contributes to AP aggravation associated with hypercholesterolemia. Oestrogen deficiency may both enhance 27HC production and exacerbate its downstream action.

Mitochondrial biogenesis disorder and oxidative damage promote refractory apical periodontitis in rat and human

AIM

To elucidate whether mitochondrial biogenesis disorder and damage from oxidative stress promote refractory apical periodontitis (RAP) in rat and human.

METHODOLOGY

Twenty Enterococcus faecalis-induced RAPs were established in the maxillary first molars of male Wistar rats. Concurrently, 12 periapical lesion specimens from patients presenting with RAP were obtained by apicoectomy. Radiographic examination and histologic analysis were conducted to evaluate periapical bone tissue destruction and morphological changes. The expression of key regulators of mitochondrial biogenesis, PGC-1α and Nrf2, were detected by immunohistochemistry and double immunofluorescence staining, Western blot and real-time PCR were also assayed. Mitochondrial ROS (mtROS) was identified by MitoSOX staining. Mitochondrial function was detected by the quantification of ATP production, mitochondrial DNA (mtDNA) copy number and activities of mitochondrial respiratory chain complexes. Furthermore, mitochondrial oxidative stress was evaluated by the determination of 3-nitrotyrosine (3-NT), 4-hydroxy-2-nonenal (4-HNE) and 8-hydroxy-deoxyguanosine (8-OHdG) expression levels, as well as malondialdehyde (MDA) expression and antioxidant capacity. Student's t-test was performed to determine significance between the groups; p < .05 was considered significant.

RESULTS

In the maxilla, significantly more bone resorption, greater number of periapical apoptotic cells and Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells were observed in the RAP group compared with the control group (p < .01). PGC-1α and Nrf2 were significantly reduced in rat and human RAP lesions compared to the control group (p < .01) at both the mRNA and protein levels. Double immunofluorescence analysis of PGC-1α or Nrf2 with TOMM20 also indicated that mitochondrial biogenesis was impaired in RAP group (p < .01). Additionally, mitochondrial dysfunction was observed in RAP group, as reflected by increased mtROS, decreased ATP production, reduced mtDNA copy number and complexes of the mitochondrial respiratory chain. Finally, the expression levels of mitochondrial oxidative stress markers, 3-NT, 4-HNE and 8-OHdG, were significantly increased in the RAP group (p < .01). Consistent with this, systemic oxidative damage was also present in the progression of RAP, including increased MDA expression and decreased antioxidant activity (p < .01).

CONCLUSIONS

Mitochondrial biogenesis disorder and damage from oxidative stress contribute to the development of RAP.

Biological evaluation of novel phosphorylated pullulan-based calcium hydroxide formulations as direct pulp capping materials: An in vivo study on a rat model

AIM

Calcium hydroxide (CH) has been considered as a direct pulp capping materials (DPC) for the last decades despite having some limitations. Phosphorylate pullulan (PPL) incorporated with CH (CHPPL) is a novel biomaterial that was introduced as a promising DPC material. Thus, the aim of the study was to evaluate the inflammatory response and mineralized tissue formation (MTF) ability of PPL-based CH formulations on rat molars after DPC.

METHODOLOGY

This study consisted of six groups: CH with 1% PPL (CHPPL-1); 3% PPL (CHPPL-3); 5% PPL (CHPPL-5); Dycal and NEX MTA Cement (N-MTA) as the positive control, and no capping materials (NC). One hundred twenty maxillary first molar cavities were prepared on Wistar rats. After capping, all the cavities were restored with 4-META/MMA-TBB resin and pulpal responses were evaluated at days 1, 7, and 28. Kruskal-Wallis followed by Mann-Whitney U-test was performed with a significance level of 0.05. Immunohistochemical expression of IL-6, Nestin, and DMP-1 was observed.

RESULTS

At day 1, CHPPL-1, N-MTA, and Dycal exhibited no to mild inflammation, whilst CHPPL-3, CHPPL-5, and NC showed mild to moderate inflammation, and the results were significantly different (p < .05). At day 7, mild to moderate inflammation was observed in CHPPL-1, N-MTA, and Dycal, whereas CHPPL-3, CHPPL-5, and NC exhibited moderate to severe inflammation. Significant differences were observed between CHPPL-1 and N-MTA with NC (p < .05), CHPPL-1 and CHPPL-3 with CHPPL-5 and Dycal (p < .05), and CHPPL-3 with N-MTA (p < .05). A thin layer of mineralized tissue formation (MTF) was observed in all groups. At day 28, CHPPL-1, Dycal, and N-MTA showed no to mild inflammation, whilst CHPPL-3, CHPPL-5, and NC exhibited mild to severe inflammation, and statistically significant difference was detected (p < .05). CHPPL-1, Dycal, and N-MTA exhibited continuous MTF, whilst CHPPL-3, CHPPL-5, and NC had thicker and interrupted MTF. Significant differences were observed between CHPPL-1, CHPPL-3, and N-MTA with NC group (p < .05). Variable expressions of IL-6, Nestin, and DMP-1 indicated differences in the materials' impact on odontoblast-like cell formation and tissue mineralization.

CONCLUSIONS

These findings suggest that CHPPL-1 has the potential to minimize pulpal inflammation and promote MTF and had similar efficacy as MTA cement.

Autophagy regulates bone loss via the RANKL/RANK/OPG axis in an experimental rat apical periodontitis model

AIM

Autophagy is involved in human apical periodontitis (AP). However, it is not clear whether autophagy is protective or destructive in bone loss via the receptor activator of nuclear factor-κB ligand (RANKL)/RANK/osteoprotegerin (OPG) axis. This study aimed to investigate the involvement of autophagy via the RANKL/RANK/OPG axis during the development of AP in an experimental rat model.

METHODOLOGY

Twenty-four female Sprague-Dawley rats were divided into control, experimental AP (EAP) + saline, and EAP + 3-methyladenine (An autophagy inhibitor, 3-MA) groups. The control group did not receive any treatment. The EAP + saline group and the EAP + 3-MA group received intraperitoneal injections of saline and 3-MA, respectively, starting 1 week after the pulp was exposed. Specimens were collected for microcomputed tomography (micro-CT) scanning, histological processing, and immunostaining to examine the expression of light chain 3 beta (LC3B), RANK, RANKL, and OPG. Data were analysed using one-way analysis of variance (p < .05).

RESULTS

Micro-CT showed greater bone loss in the EAP + 3-MA group than in the EAP + saline group, indicated by an elevated trabecular space (Tb.Sp) (p < .05). Inflammatory cell infiltration was observed in the EAP + saline and EAP + 3-MA groups. Compared with EAP + saline group, the EAP + 3-MA group showed weaker expression of LC3B (p < .01) and OPG (p < .05), more intense expression of RANK (p < .01) and RANKL (p < .01), and a higher RANKL/OPG ratio (p < .05).

CONCLUSION

Autophagy may exert a protective effect against AP by regulating the RANKL/RANK/OPG axis, thereby inhibiting excessive bone loss.

Antibiofilm effect of different concentrations of silver nanoparticles combined with calcium hydroxide against Enterococcus faecalis biofilm: An ex vivo study

This study aimed to evaluate the antibiofilm activity of different concentrations of silver nanoparticles (AgNPs) in combination with calcium hydroxide [Ca(OH)2] against Enterococcus faecalis biofilm. On an E. faecalis biofilm on dentin discs, the following medicaments were applied for 7 days (n = 13/group): 0.005% AgNPs+Ca(OH)2, 0.01% AgNPs+Ca(OH)2, 0.02% AgNPs + Ca(OH)2, Ca(OH)2 and saline/control. Specimens were stained with LIVE/DEAD® BacLight™ dye and analysed with confocal laser scanning microscopy. Proportion of dead bacteria was calculated and analysed. There was a significant reduction in E. faecalis biofilm in all medicament groups (43.5%, 49.1%, 69.1%, 48.7%) respectively, compared with control group (2.54%) (p < 0.001). The 0.02% AgNPs + Ca(OH)2 group demonstrated the most significantly superior antibiofilm effect, with no significant difference between remaining groups. In conclusion, combining 0.02% AgNPs enhanced the antibiofilm effect of Ca(OH)2 on E. faecalis biofilm compared with lower AgNPs concentrations.

Effects of melatonin against experimentally induced apical periodontitis in rats

Apical periodontitis is an inflammatory condition resulting from microbial invasion in the root canal system, causing periapical tissue destruction and bone resorption. This study investigated melatonin's effects, known for its antioxidant and anti-inflammatory properties, on experimentally induced apical periodontitis in rats. Three groups of rats were studied: control, apical periodontitis and apical periodontitis with melatonin treatment. Proinflammatory cytokines and enzyme levels in blood serum were measured, and micro-CT analysis assessed bone resorption. Results showed significantly elevated cytokines and enzyme levels in the apical periodontitis group compared to the control. However, in the melatonin-treated group, these levels were significantly reduced (p < 0.01-0.001). Micro-CT analysis indicated decreased periapical resorption cavity volume and surface area with melatonin treatment. This suggests that systemic melatonin administration can mitigate inflammation and reduce bone resorption in experimentally induced apical periodontitis in rats, potentially holding promise for human endodontic disease treatment pending further research.

PRIDASE 2024 guidelines for reporting diagnostic accuracy studies in endodontics: A consensus-based development

Studies investigating the accuracy of diagnostic tests should provide data on how effectively they identify or exclude disease in order to inform clinicians responsible for managing patients. This consensus-based project was undertaken to develop reporting guidelines for authors submitting manuscripts, which describe studies that have evaluated the accuracy of diagnostic tests in endodontics. These guidelines are known as the Preferred Reporting Items for Diagnostic Accuracy Studies in Endodontics (PRIDASE) 2024 guidelines. A nine-member steering committee created an initial checklist by integrating and modifying items from the Standards for Reporting of Diagnostic Accuracy (STARD) 2015 checklist and the Clinical and Laboratory Images in Publications (CLIP) principles, as well as adding a number of new items specific to the specialty of endodontics. Thereafter, the steering committee formed the PRIDASE Delphi Group (PDG) and the PRIDASE Online Meeting Group (POMG) in order to collect expert feedback on the preliminary draft checklist. Members of the Delphi group engaged in an online Delphi process to reach consensus on the clarity and suitability of the items in the checklist. The online meeting group then held an in-depth discussion on the online Delphi-generated items via the Zoom platform on 20 October 2023. According to the feedback obtained, the steering committee revised the PRIDASE checklist, which was then piloted by several authors when preparing manuscripts describing diagnostic accuracy studies in endodontics. Feedback from this process resulted in the final version of the PRIDASE 2024 checklist, which has 11 sections and 66 items. Authors are encouraged to use the PRIDASE 2024 guidelines when developing manuscripts on diagnostic accuracy in endodontics in order to improve the quality of reporting in this area. Editors of relevant journals will be invited to include these guidelines in their instructions to authors.

Resolvin D2-induced reparative dentin and pulp stem cells after pulpotomy in a rat model

Introduction

Vital pulp therapy (VPT) is performed to preserve dental pulp. However, the biocompatibility of the existing materials is of concern. Therefore, novel materials that can induce pulp healing without adverse effects need to be developed. Resolvin D2 (RvD2), one of specialized pro-resolving mediators, can resolve inflammation and promote the healing of periapical lesions. Therefore, RvD2 may be suitable for use in VPT. In the present study, we evaluated the efficacy of RvD2 against VPT using in vivo and in vitro models.

Methods

First molars of eight-week-old male Sprague-Dawley rats were used for pulpotomy. They were then divided into three treatment groups: RvD2, phosphate-buffered saline, and calcium hydroxide groups. Treatment results were assessed using radiological, histological, and immunohistochemical (GPR18, TNF-α, Ki67, VEGF, TGF-β, CD44, CD90, and TRPA1) analyses. Dental pulp-derived cells were treated with RvD2 in vitro and analyzed using cell-proliferation and cell-migration assays, real-time PCR (Gpr18, Tnf-α, Il-1β, Tgf-β, Vegf, Nanog, and Trpa1), ELISA (VEGF and TGF-β), immunocytochemistry (TRPA1), and flow cytometry (dental pulp stem cells: DPSCs).

Results

The formation of calcified tissue in the pulp was observed in the RvD2 and calcium hydroxide groups. RvD2 inhibited inflammation in dental pulp cells. RvD2 promoted cell proliferation and migration and the expression of TGF-β and VEGF in vitro and in vivo. RvD2 increased the number of DPSCs. In addition, RvD2 suppressed TRPA1 expression as a pain receptor.

Conclusion

RvD2 induced the formation of reparative dentin, anti-inflammatory effects, and decreased pain, along with the proliferation of DPSCs via the expression of VEGF and TGF-β, on the pulp surface in pulpotomy models.

Systemic administration of propranolol reduces bone resorption and inflammation in apical periodontitis of chronically stressed rats

AIM

To evaluate the effect of systemic administration of propranolol on the severity of apical periodontitis (AP) in chronically stressed rats.

METHODOLOGY

Twenty-four 70-day-old male Wistar rats (Rattus norvegicus, albinus) were distributed into three groups (n = 8): rats with AP without stressful conditions (AP-Control), rats with AP and submitted to a chronic unpredictable stress (CUS) protocol (AP + S) and rats with AP and submitted to a CUS protocol treated with propranolol (AP + S + PRO). Stress procedures were applied daily until the end of the experiment. After 3 weeks of CUS, AP was induced in all groups by exposing the pulpal tissue of mandibular and maxillary first molars to the oral environment. Propranolol treatment was administered orally once a day for the entire period of the experiment. Rats were sacrificed at 42 days, and the blood was collected for stress biomarkers serum dosage by multiplex assay. Mandibles were removed and submitted to microtomography and histopathological analyses. Periapical tissue surrounding the upper first molar was homogenized and subjected to RT-PCR analysis to evaluate the mRNA expression of RANKL, TRAP and OPG. Parametric data were assessed using one-way ANOVA followed by Tukey's test while the nonparametric data were analysed by the Kruskal-Wallis followed by Dunn's test. Significance level was set at 5% (p < .05) for all assessed parameters.

RESULTS

Micro-CT revealed statistically significant differences in bone resorption which was greater in the AP + S group (p < .05), but no differences were observed between the Control and AP + S + PRO groups (p > .05). The AP + S + PRO group had a lower intensity and extent of inflammatory infiltrate compared to the AP + S group with smaller areas of bone loss (p < 0.05). The gene expression of RANKL and TRAP was significantly higher in the stressed group AP + S compared to the control group (p < .05), and a significantly higher OPG expression was observed in AP + S + PRO compared to the AP + S group (p < .05).

CONCLUSIONS

Oral administration of propranolol had a significant effect on the AP severity in stressed rats, suggesting an anti-inflammatory effect and a protective role on bone resorption of AP in stressed animals. Further research is necessary to fully comprehend the underlying mechanisms.

Effects of mineral trioxide aggregate and methyl sulfonyl methane on pulp exposure via RUNX2 and RANKL pathways

The aim of this study was to determine the therapeutic effects of mineral trioxide aggregate (MTA) and methyl sulfonyl methane (MSM) on pulp damage due to pulp exposure through the RUNX2 and RANKL pathways. Seventy-two male Sprague-Dawley rats aged 4-6 months and weighing 250-300 g were divided into healthy, control, MTA, and MSM groups. After experimental applications, all rats at 2, 4, and 8 weeks were killed anesthetically with xylazine hydrochloride (Rompun, Bayer) 30 mg/kg and ketamine hydrochloride (Ketalar, Pfizer) 50 mg/kg injections (i.p.). We observed that necrotic odontoblasts, edema, inflammation, and vascular congestion findings were reduced from week 2 to week 8 in the MSM treatment group after pulp capping compared to the control group and MTA group. Similarly, we found a decrease in RUNX2 and RANKL levels in the MSM application group compared to the control and MTA groups (p < 0.05). MSM material has shown therapeutic effects on pulp capping treatment-induced pulp injury via increased RUNX2 ve RANKL expression.

Biocompatibility and bioactive potential of NeoPUTTY calcium silicate-based cement: An in vivo study in rats

AIM

To evaluate the inflammatory reaction and the ability to induce mineralization activity of a new repair material, NeoPUTTY (NPutty; NuSmile, USA), in comparison with Bio-C Repair (BC; Angelus, Brazil) and MTA Repair HP (MTA HP; Angelus, Brazil).

METHODOLOGY

Polyethylene tubes were filled with materials or kept empty (control group, CG) and implanted in subcutaneous tissue of rats for 7, 15, 30, and 60 days (n = 6/group). Capsule thickness, number of inflammatory cells (ICs), fibroblasts, collagen content, and von Kossa analysis were performed. Unstained sections were evaluated under polarized light and by immunohistochemistry for osteocalcin (OCN). Data were submitted to two-way anova followed by Tukey's test (p ≤ .05), except for OCN. OCN data were submitted to Kruskal-Wallis and Dunn and Friedman post hoc tests followed by the Nemenyi test at a significance level of 5%.

RESULTS

At 7, 15, and 30 days, thick capsules containing numerous ICs were seen around the materials. At 60 days, a moderate inflammatory reaction was observed for NPutty, BC while MTA HP presented thin capsules with moderate inflammatory cells. In all periods, NPutty specimens contained the highest values of ICs (p < .05). From 7 to 60 days, the number of ICs reduced significantly while an increase in the number of fibroblasts and birefringent collagen content was observed. At 7 and 15 days, no significant difference was observed in the immunoexpression of OCN (p > .05). At 30 and 60 days, NPutty showed the lowest values of OCN (p < .05). At 60 days, a similar immunoexpression was observed for BC and MTA HP (p > .05). In all time intervals, capsules around NPutty, BC, and MTA HP showed von Kossa-positive and birefringent structures.

CONCLUSIONS

Despite the greater inflammatory reaction promoted by NeoPutty than BC and MTA HP, the reduction in the thickness of capsules, the increase in the number of fibroblasts, and the reduction in the number of ICs indicate that this bioceramic material is biocompatible Furthermore, NeoPutty presents the ability to induce mineralization activity.

Final irrigation with bioglass solution in regenerative endodontic procedure induces tissue formation inside the root canals, collagen maturation, proliferation cell and presence of osteocalcin

AIM

To evaluate the influence of an experimental solution of cobalt-doped F18 bioactive glass (F18Co) on tissue repair following regenerative endodontic procedure (REP) in rat molars.

METHODOLOGY

The F18Co solution was prepared at a ratio of 1:5 F18Co powder to distilled water. The right or left upper first molars of 12 Wistar rats were used, where the pulps were exposed, removed, and irrigated with 2.5% sodium hypochlorite (NaOCl), followed by 17% ethylenediaminetetraacetic acid (EDTA) (5 min each). Subsequently, the molars were divided into two groups (n = 6): REP-SS and REP-F18Co, where they received a final irrigation (5 min) with saline solution (SS) or F18Co solution, respectively. Then, intracanal bleeding was induced, and the tooth was sealed. Untreated molars were used as controls (n = 3). At 21 days, the rats were euthanized, and the specimens were processed for analysis of mineralized tissue and soft tissue formation inside the root canal using haematoxylin-eosin. The presence and maturation of collagen were evaluated by Masson's trichrome and picrosirius red staining. Immunolabelling analyses of proliferating cell nuclear antigen (PCNA) and osteocalcin (OCN) were performed. The data were submitted to the Mann-Whitney U-test (p < .05).

RESULTS

There was a similar formation of mineralized tissue in thickness and length in REP-SS and REP-F18Co groups (p > .05). Regarding the presence of newly formed soft tissue, most specimens of the REP-F18Co had tissue formation up to the cervical third of the canal, whilst the REP-SS specimens showed formation up to the middle third (p < .05), and there was higher maturation of collagen in REP-F18Co (p < .05). The number of PCNA-positive cells found in the apical third of the root canal was significantly higher in the F18Co group, as well as the OCN immunolabelling, which was severe in most specimens of REP-F18Co, and low in most specimens of REP-SS.

CONCLUSION

The final irrigation with F18Co bioactive glass solution in REP did not influence mineralized tissue formation but induced soft tissue formation inside the root canals, with higher collagen maturation, and an increase in PCNA-positive cells and OCN immunolabelling.

The effects of NLRP3 inflammasome inhibition or knockout in experimental apical periodontitis induced in mice

OBJECTIVE

To evaluate the effects of NLRP3 inflammasome inhibition or knockout in experimental apical periodontitis (AP) induced in mice.

METHODS

The experimental AP was induced by pulpal exposure. To evaluate NLRP3-specific inhibitor medication (MCC950), WT mice received intraperitoneal injections, while the control received PBS (n = 10). In addition, to evaluate NLRP3 knockout, 35 wild-type (WT) and 35 NLRP3-/- mice were divided into a control group (without pulpal exposure, n = 5) and three experimental groups: after 2, 14 and 42 days after pulpal exposure (n = 10). Microscopic and molecular analyzes were carried out using a significance level of 5%.

RESULTS

Exposure to MCC950 did not affect the periapical lesion size after 14 days (P = 0.584). However, exposed mice had a lower expression of IL-1β, IL-18 and caspase-1 (P = 0.010, 0.016 and 0.002, respectively). Moreover, NLRP3-/- mice showed a smaller periapical lesion after 14 and 42 days (P = 0.023 and 0.031, respectively), as well as a lower expression of IL-1β after 42 days (P < 0.001), of IL-18 and caspase-1 after 14 (P < 0.001 and 0.035, respectively) and 42 days (P = 0.002 and 0.002, respectively). NLRP3-/- mice also showed a lower mRNA for Il-1β, Il-18 and Casp1 after 2 (P = 0.002, 0.036 and 0.001, respectively) and 14 days (P = 0.002, 0.002 and 0.001, respectively).

CONCLUSIONS

NLRP3 inflammasome inhibition or knockout can attenuate the inflammatory events that result in the periapical lesion (AP) formation after pulpal exposure in mice.

CLINICAL RELEVANCE

The NLRP3 inflammasome may be a therapeutic target for AP, and new approaches may verify the impact of its inhibition (through intracanal medications or filling materials) on the bone repair process and treatment success.

Rev-erbα attenuates refractory periapical periodontitis via M1 polarization: An in vitro and in vivo study

AIM

Rev-erbα has been reported to regulate the healing of inflammatory lesions through its effect on the immune system in a variety of inflammatory disease. Moreover, the balance of macrophages polarization plays a crucial role in immune response and inflammatory progression. However, in refractory periapical periodontitis (RAP), the role of Rev-erbα in inflammatory response and bone resorption by regulating macrophage polarization remains unclarified. The aims of the present study were to investigate the expression of Rev-erbα in experimental RAP and to explore the relationship between Rev-erbα and macrophage polarization through the application of its pharmacological agonist SR9009 into the in vivo and in vitro experiments.

METHODOLOGY

Enterococcus faecalis-induced RAP models were established in SD rats. Histological staining and micro-computed tomography scanning were used to evaluate osteoclastogenesis and alveolar bone resorption. The expression of Rev-erbα and macrophage polarization were detected in the periapical tissues from rats by immunofluorescence, flow cytometry, and western blots. Furthermore, immunohistochemical staining and enzyme-linked immunosorbent assay were performed to explore the relationship between Rev-erbα and inflammatory cytokines related to macrophage polarization.

RESULT

Compared to healthy periapical tissue, the expression of Rev-erbα was significantly down-regulated in macrophages from inflammatory periapical area, especially in Enterococcus faecalis-induced periapical lesions, with obvious type-1 macrophage (M1)-like dominance and the production of pro-inflammatory cytokines. In addition, Rev-erbα activation by SR9009 could induce type-2 macrophage (M2)-like polarization in periapical tissue and THP1 cell line, followed by increased secretion of anti-inflammatory cytokines IL-10 and TGF-β. Furthermore, intracanal application of SR9009 reduced the lesion size and promoted the repair of RAP by decreasing the number of osteoclasts and enhancing the formation of mineralized tissue in periapical inflammatory lesions.

CONCLUSIONS

Rev-erbα played an essential role in the pathogenesis of RAP through its effect on macrophage polarization. Targeting Rev-erbα might be a promising and prospective therapy method for the prevention and management of RAP.

Effect of intra-alveolar delivery of Frondoside A on inflammatory response of delayed tooth replantation

BACKGROUND/AIM

Frondoside A is a sea cucumber extract which is well known for its anti-inflammatory and immunomodulatory properties. The purpose of this study was to evaluate the effect of Frondoside A application in the alveolar socket on inflammatory responses after delayed replantation in rat teeth.

MATERIALS AND METHODS

Human periodontal ligament cells were cultured and exposed to Frondoside A. Cell-counting kit-8 assay was performed to evaluate the cell viability and nitric oxide assay was performed to assess the anti-inflammatory effect of Frondoside A. Molars were extracted from 32 Sprague-Dawley rats and randomly divided into control and Frondoside A groups. After 30 min of extra-oral dry time, molars were replanted. In the Frondoside A group, Frondoside A solution was applied in the alveolar socket before replantation. The animals were sacrificed after 28 days and histologically and immunohistochemically evaluated.

RESULTS

0.5 μM Frondoside A showed higher cellular viability at 6 h and lower production of nitric oxide compared with other Frondoside A solutions (p < .05). The Frondoside A group demonstrated lower inflammatory resorption scores in both middle 1/3 and apical 1/3 of root compared to the control group (p < .05). The Frondoside A group showed lower levels of expression in both cathepsin K and CD45 compared with the control group (p < .05).

CONCLUSIONS

Within the limits of this study, intra-alveolar delivery of Frondoside A alleviates inflammatory root resorption in delayed replantation of rat teeth.

Hard tissue formation in pulpotomized primary teeth in dogs with nanomaterials MCM-48 and MCM-48/hydroxyapatite: an in vivo animal study

BACKGROUND

This animal study sought to evaluate two novel nanomaterials for pulpotomy of primary teeth and assess the short-term pulpal response and hard tissue formation in dogs. The results were compared with mineral trioxide aggregate (MTA).

METHODS

This in vivo animal study on dogs evaluated 48 primary premolar teeth of 4 mongrel female dogs the age of 6-8 weeks, randomly divided into four groups (n = 12). The teeth underwent complete pulpotomy under general anesthesia. The pulp tissue was capped with MCM-48, MCM-48/Hydroxyapatite (HA), MTA (positive control), and gutta-percha (negative control), and the teeth were restored with intermediate restorative material (IRM) paste and amalgam. After 4-6 weeks, the teeth were extracted and histologically analyzed to assess the pulpal response to the pulpotomy agent.

RESULTS

The data were analyzed using the Kruskal‒Wallis, Fisher's exact, Spearman's, and Mann‒Whitney tests. The four groups were not significantly different regarding the severity of inflammation (P = 0.53), extent of inflammation (P = 0.72), necrosis (P = 0.361), severity of edema (P = 0.52), extent of edema (P = 0.06), or connective tissue formation (P = 0.064). A significant correlation was noted between the severity and extent of inflammation (r = 0.954, P < 0.001). The four groups were significantly different regarding the frequency of bone formation (P = 0.012), extent of connective tissue formation (P = 0.047), severity of congestion (P = 0.02), and extent of congestion (P = 0.01). No bone formation was noted in the gutta-percha group. The type of newly formed bone was not significantly different among the three experimental groups (P = 0.320).

CONCLUSION

MCM-48 and MCM-48/HA are bioactive nanomaterials that may serve as alternatives for pulpotomy of primary teeth due to their ability to induce hard tissue formation. The MCM-48 and MCM-48/HA mesoporous silica nanomaterials have the potential to induce osteogenesis and tertiary (reparative) dentin formation.

TLR2 agonist prevents the progression of periapical lesions in mice by reducing osteoclast activity and regulating the frequency of Tregs

AIM

To evaluate the role of regulatory T lymphocytes (Tregs) in the presence or absence of the synthetic ligand Pam3Cys during the progression of periapical lesion in wild-type (WT) and toll-like receptor 2 knockout (TLR2KO) mice.

METHODOLOGY

A total of 130 C57BL/6 male WT and TLR2KO mice were allocated into control (n = 5) and experimental (periapical lesion induction) (n = 10) groups. In specific groups (WT+Pam3cys and TLR2KO+Pam3cys), the synthetic ligand Pam3cys was administered intraperitoneally every 7 days, according to the experimental period (14, 21 and 42 days). At the end of those periods, the animals were euthanized, and the mandible and the spleen were submitted to histotechnical processing. Mandible histological sections were analysed by haematoxylin and eosin, TRAP histoenzymology and immunohistochemistry (FOXP3, RANK, RANKL and OPG). Spleen sections were analysed by immunohistochemistry (FOXP3).

RESULTS

The inflammatory infiltrate and bone resorption were more intense in the TLR2KO group compared to the WT group. The animals that received the Pam3cys had smaller periapical lesions when compared to the animals that did not receive the ligand (p < .05). TLR2KO animals showed a significant increase in the number of osteoclasts when compared to TLR2KO+Pam3cys group (p < .05). At 21 days, the WT+Pam3cys group had a lower number of osteoclasts when compared to the WT animals (p = .02). FOXP3 expression was more intense in the WT+Pam3cys groups when compared to the WT animals in the 42 days (p = .03). In the spleen analysis, the WT+Pam3cys group also had a higher expression of FOXP3 when compared to the WT animals at 14 and 42 days (p = .02). Concerning RANKL, there was a reduction in staining in the KOTLR2+Pam3cys groups at 21 and 42 days (p = .03) and a higher binding ratio between RANK/RANKL in animals that did not receive the ligand.

CONCLUSION

Administration of the Pam3cys increased the proliferation of Tregs, showed by FOXP3 expression and prevented the progression of the periapical lesion in WT mice. On the other hand, in the TLR2KO animals, Treg expression was lower with larger areas of periapical lesions. Finally, systemic administration of the Pam3cys in KO animals was able to limit the deleterious effects of the absence of the TLR2 receptor.

Effects of N-acetyl-L-cysteine against apical periodontitis in rats with adriamycin-induced cardiomyopathy and nephropathy

AIM

This study aimed to investigate the potential protective effects of N-acetyl-L-cysteine (NAC) against apical periodontitis (AP) in rats with adriamycin (ADR)-induced kidney and heart diseases.

METHODOLOGY

Fourty-eight Wistar albino rats were divided into six groups: (1) Control group, (2) ADR group (1 mg/kg/day ip for 10 days), (3) AP Group (1st mandibular molar tooth), (4) AP + ADR Group, (5) AP + NAC group (150 mg/kg/day ip), and (6) AP + ADR + NAC group. After 3 weeks, the rats were decapitated and blood and tissue samples (heart, kidney, and jaw) were collected. Tissue samples were evaluated by biochemical (inflammatory cytokines and hemodynamic parameters) and radiological analyses. One-way anova with Tukey post hoc tests was used to compare data, considering p < .05 as statistically significant.

RESULTS

The serum levels of TNF-α, IL-1β, BUN, Creatinine, CK, and LDH were elevated in the test groups compared with the control group, and treatment with NAC reduced these levels (p < .05). Heart and kidney tissue analysis showed a higher heart-to-body weight ratio (HW/BW) and kidney-to-body weight ratio (KW/BW) in the test groups compared with the control group (p < .05). No significant differences in HW/BW and KW/BW were found between the control and AP + NAC groups. Volumetric apical bone resorption analysis showed an increase in periapical radiolucencies in AP-induced groups indicating apical periodontitis. NAC treatment reduced the total area and volume of resorption cavities (p < .05).

CONCLUSIONS

The results suggest that NAC's antioxidant and anti-inflammatory effects can reduce adriamycin-mediated heart and kidney damage and may have a positive effect on apical periodontitis in individuals with nephropathy and cardiomyopathy.

Chronic alcohol and nicotine consumption as catalyst for systemic inflammatory storm and bone destruction in apical periodontitis

AIM

To assess the periapical alveolar bone pattern and the serum levels of proinflammatory cytokines, biochemical markers and metabolites in rats subjected to chronic alcohol and nicotine consumption and induced apical periodontitis.

METHODOLOGY

Twenty-eight male Wistar rats were divided into four groups: Control, Alcohol, Nicotine and Alcohol+Nicotine. The alcohol groups were exposed to self-administration of a 25% alcohol solution, while the other groups were given only filtered water. The nicotine groups received daily intraperitoneal injections of a nicotine solution (0.19 μL of nicotine/mL), whereas the other groups received saline solution. Periapical lesions were induced by exposing the pulps of the left mandibular first molars for 28 days. After euthanasia, the mandibles were removed and the percentage bone volume, bone mineral density, trabecular thickness, trabecular separation and trabecular number of the periapical bone were measured using micro-computed tomography images. Serum samples were collected for analysis of proinflammatory cytokines (IL-1β, IL-4, IL-6 and TNF-α), biochemical and metabolomic analysis. Statistical analysis was performed with a significance level of 5%. Nonparametric data were analysed using the Kruskal-Wallis test followed by Dunn's test, while one-way anova followed by Tukey's test was performed for parametric data.

RESULTS

The groups exposed to alcohol or nicotine consumption exhibited an altered bone pattern indicating lower bone density and higher levels of IL-1β, IL-6 and TNF-α compared to the Control group (p < .05). Significant differences were observed among the groups in the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase, cholesterol, triglycerides, urea, creatinine, albumin, uric acid, bilirubin and calcium. Metabolomic analysis revealed significant differences in glycine, phosphocholine, lysine, lactate, valine, pyruvate and lipids (CH2 CH2 CO), n(CH2 ) and n(CH3 ). Most of these parameters were even more altered in the simultaneous consumption of both substances compared to single consumption.

CONCLUSION

Alcohol and nicotine chronic consumption altered several metabolic markers, impaired liver and kidney function, increased the production of systemic proinflammatory mediators and harmed the periapical bone microarchitecture in the presence of apical periodontitis. The simultaneous consumption of alcohol and nicotine intensified these detrimental effects.

A scoping review on efficacy and safety of medicinal plants used for the treatment of diarrhea in sub-Saharan Africa

BACKGROUND

In sub-Saharan Africa (SSA), significant morbidity and mortality have been linked to diarrhea, which is frequently caused by microorganisms. A rise in antimicrobial-resistant pathogens has reignited the search for alternative therapies. This scoping review aims to map the literature on medicinal plants in relation to their anti-diarrheal potential from SSA.

METHODS

Studies published from 1990 until April 2022 on medicinal plants used for the treatment of diarrhea from each country in SSA were searched on Scopus, Web of Science, Science Direct and PubMed. The selection of articles was based on the availability of data on the in vitro and/or in vivo, ethnobotanical, and cross-sectional studies on the efficacy of medicinal plants against diarrhea. A total of 67 articles (ethnobotanical (n = 40); in vitro (n = 11), in vivo (n = 7), cross-sectional (n = 3), in vitro and in vivo (n = 2) and ethnobotanical and in vitro (n = 2), were considered for the descriptive analysis, which addressed study characteristics, herbal intervention information, phytochemistry, outcome measures, and toxicity findings.

RESULTS

A total of 587 different plant species (from 123 families) used for diarrhea treatment were identified. Most studies were conducted on plants from the Fabaceae family. The plants with the strongest antimicrobial activity were Indigofera daleoides and Punica granatum. Chromatographic methods were used to isolate six pure compounds from ethyl acetate extract of Hydnora johannis, and spectroscopic methods were used to determine their structures. The majority of anti-diarrheal plants were from South Africa (23.9%), Ethiopia (16.4%), and Uganda (9%). This study highlights the value of traditional remedies in treating common human diseases such as diarrhea in SSA.

CONCLUSION

Baseline knowledge gaps were identified in various parts of SSA. It is therefore recommended that future ethnobotanical studies document the knowledge held by other countries in SSA that have so far received less attention. Additionally, we recommend that future studies conduct phytochemical investigations, particularly on the widely used medicinal plants for the treatment of diarrheal illnesses, which can serve as a foundation for future research into the development of contemporary drugs.

Effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats

OBJECTIVE

To evaluate the effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats.

METHODOLOGY

In total, 32 male Wistar rats were divided into four groups (n = 8): AP-induced apical periodontitis; S-cigarette smoke inhalation; APS-induced AP and cigarette smoke inhalation; and C (control)-neither AP nor cigarette smoke inhalation. To induce cigarette smoke inhalation, the animals were kept in a chamber filled with tobacco smoke for 8 min thrice a day for 50 days. AP was induced 20 days after inhalation initiation by exposing their coronary pulp to their oral environment for 30 days. After animals were euthanized, their right hemimaxillae were removed for histopathological, semi-quantitative and immunohistochemical (F4/80, CD206 and iNOS) analyses.

RESULTS

Quantitative data showed a moderate number of inflammatory infiltrates in AP and an intense number in APS (p < .05). Comparing F4/80+ cells showed no statistically significant differences among groups, but we found more CD206+ cells in AP than in C and S (p > .05). INOS+ immunostaining showed a significant increase in AP and APS, when compared with C and S (p < .05). APS had more iNOS+ cells than AP (p < .05).

CONCLUSION

Cigarette smoke inhalation worsened AP, leading to a predominantly pro- inflammatory profile in our experimental model.

The N6-methyladenosine demethylase FTO is required for odontoblast differentiation in vitro and dentine formation in mice by promoting RUNX2 exon 5 inclusion through RBM4

AIM

Fat mass and obesity-associated (FTO) protein, the first discovered N6-methyladenine (m6A) demethylase, played positive roles in bone formation. In this study, the aim was to investigate the function and potential mechanism of Fto in dentine formation.

METHODOLOGY

In vivo model, postnatal 12-day (PN12), 4-week-old (4 wk), 6-week-old (6 wk) healthy male C57BL/6J were randomly divided into Fto knockout (Fto-/- ) mice and wild-type (WT) littermates according to their genotypes, with 3-5 mice in each group. The mandibles of Fto-/- mice and WT control littermates were isolated for analysis by micro-computed tomography (micro-CT), 3-dimensional reconstruction and Haematoxylin-eosin (HE) staining. In vitro, mouse dental papilla cells (mDPCs) and human dental stem pulp cells (hDPSCs) were cultured with odontogenetic medium to evaluate differentiation capacity; expression levels of odontoblastic related genes were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). The inclusion levels of Runt-related transcription factor 2 (RUNX2) exon 5 in mDPCs and hDPSCs were detected by semiquantitative real-time polymerase chain reaction (RT-PCR). The RNA binding motif protein 4 (RBM4) m6A site was verified through m6A methylated RNA immunoprecipitation (MeRIP) and the stability of RBM4 mRNA influenced by FTO knockdown was measured by mRNA stability assay. Differences with p values < .05 were regarded as statistically significant.

RESULTS

We discovered that Fto-/- mice showed significant dentine formation defects characterized by widened pulp cavity, enlarged pulp-tooth volume ratio, thinned dentine and pre-dentine layer of root (p < .05). Fto-/- mDPCs and FTO-silencing hDPSCs not only exhibited insufficient mineralization ability and decreased expression levels of odontoblastic mineralization related genes (p < .05), but showed significantly reduced Runx2 exon 5 inclusion level (p < .05). FTO knockdown increased the m6A level of RBM4 and destabilized the mRNA of RBM4, thus contributing to the reduced RBM4 expression level. Moreover, Rbm4 overexpression in Fto-/- mDPCs can partly restore Runx2 exon 5 inclusion level and the differentiation ability disrupted by Fto knockout.

CONCLUSION

Thus, within the limitations of this study, the data suggest that FTO promotes odontoblastic differentiation during dentine formation by stabilizing RBM4 mRNA to promote RUNX2 exon 5 inclusion.

Critical analysis of the reporting quality of animal studies within Endodontics using the Preferred Reporting Items for Animal Studies in Endodontics (PRIASE) 2021 quality standard checklist

AIM

To critically evaluate the reporting quality of a random sample of animal studies within the field of endodontics against the Preferred Reporting Items for Animal Studies in Endodontics (PRIASE) 2021 checklist and to investigate the association between the quality of reporting and several characteristics of the selected studies.

METHODOLOGY

Fifty animal studies related to endodontics were randomly selected from the PubMed database with publication dates from January 2017 to December 2021. For each study, a score of '1' was given when the item of the PRIASE 2021 checklist was fully reported, whereas a score of '0' was given when an item was not reported; when the item was inadequately or partially reported, a score of '0.5' was given. Based on the overall scores allocated to each manuscript, they were allocated into three categories of reporting quality: low, moderate and high. Associations between study characteristics and reporting quality scores were also analysed. Descriptive statistics and Fisher's exact tests were used to describe the data and determine associations. The probability value of .05 was selected as the level of statistical significance.

RESULTS

Based on the overall scores, four (8%) and 46 (92%) of the animal studies evaluated were categorized as 'High' and 'Moderate' reporting quality, respectively. A number of items were adequately reported in all studies related to background (Item 4a), relevance of methods/results (7a) and interpretation of images (11e), whereas only one item related to changes in protocol (6d) was not reported in any. No associations were confirmed between reporting quality scores and number of authors, origin of the corresponding author, journal of publication (endodontic specialty vs. non- specialty), impact factor or year of publication.

CONCLUSIONS

Animal studies published in the specialty of endodontics were mostly of 'moderate' quality in terms of the quality of reporting. Adherence to the PRIASE 2021 guidelines will enhance the reporting of animal studies in the expectation that all future publications will be high quality.

Inflammatory response and odontogenic differentiation of inflamed dental pulp treated with different pulp capping materials: An in vivo study

AIM

Previous studies have evaluated the pulpal responses to calcium silicate cements (CSCs) on normal dental pulp, but investigations on the effects of CSCs on inflamed pulp are limited. This study aimed to test the inflammatory response and odontogenic differentiation of inflamed rat dental pulp after direct pulp capping with CSCs.

METHODOLOGY

Wistar rat molars pulps were exposed for 48 h to induce inflammation and then capped with ProRoot MTA (Dentsply), Biodentine (Septodont), RetroMTA (Bio MTA) and Dycal (Dentsply Caulk). The degree of pulpal inflammation and hard tissue formation was evaluated by histological analysis. Immunofluorescence staining for interleukin (IL)-6, osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2) was also performed.

RESULTS

After 4 weeks, complete recovery from inflammation was evident in 22%, 37.5%, 10% and none of the ProRoot MTA, Biodentine, RetroMTA and Dycal samples, respectively. Heavy hard tissue deposition as a continuous hard tissue bridge was observed in 77.8%, 75%, 70% and 60% of the ProRoot MTA, Biodentine, RetroMTA and Dycal samples, respectively. IL-6, OCN and RUNX2 were detected in all materials, mainly adjacent to areas of inflammation and reparative dentine formation. At one, two and 4 weeks, significant differences were not observed between the inflammation and hard tissue formation scores of the four material groups (p > .05).

CONCLUSIONS

In this study, pulpal inflammation was still present in most specimens at 4 weeks after pulp capping and a significant number of samples showed incomplete and discontinuous dentine bridge formation. The results of this study suggest that initial inflammatory conditions of the pulp may risk the prognosis of teeth treated with CSCs.

Nano eggshell-based slurry as a direct pulp-capping material: In vitro characterization and histopathological assessment in an experimental animal model

AIM

Pulp vitality is essential for tooth integrity. Following pulp exposure, choosing a suitable pulp-capping material is crucial to maintain pulp vitality. However, the reparative dentine bridge created by calcium hydroxide (Ca(OH)2 ) is generally porous and incomplete. The aim of the current study is to assess the in vitro and in vivo bioactivities of nano eggshell-based slurry (NES), using NES as a direct pulp-capping material, compared with Ca(OH)2 in rabbit animal model.

METHODOLOGY

Nano eggshell powder (NE) was characterized for particle morphology, chemical composition and ion release. In vitro bioactivity was tested by immersion in simulated body fluid (SBF) for 7 days. For histopathological evaluation, 36 adult New Zealand rabbits (72 pulp exposures) were divided into nine groups (n = 8) according to the pulp-capping material (NES, Ca(OH)2 and no capping as negative control group) and the animals were sacrificed after 7, 14 or 28 days. The pulps of the two lower central incisors were exposed and then directly capped by Ca(OH)2 or NES or left untreated. The cavities were then sealed with glass ionomer cement. Teeth were collected for histopathological evaluation using an optical microscope. Pulp haemorrhage, inflammation, fibrosis and calcific bridge formation were assessed. Results were statistically analysed using anova and Tukey's tests.

RESULTS

Nano eggshell particles were spherical with a 20 nm diameter and were composed mainly of calcite. Statistical analysis showed that there was a significant increase in the release of all investigated ions between days 1 and 28, except for copper. NES group showed a significantly higher release of all elements as compared to Ca(OH)2 . Environmental scanning electron microscope micrographs of NES incubated for 7 days in SBF showed the formation of HAp with a Ca/P ratio (1.686). For histopathological evaluation, the difference between groups was statistically significant. At day 28, 75% of the pulps of the Ca(OH)2 group showed mild calcific bridge in comparison with 100% moderate calcific bridge in the NES group. The NES group showed significantly less inflammation at days 7 and 28, and higher fibrosis at day 7 compared with Ca(OH)2 .

CONCLUSIONS

Nano eggshell-based slurry represents a promising novel direct pulp-capping material with favourable pulp tissue response.

Inflammatory profile of apical periodontitis exacerbated by cigarette smoke inhalation: Histological and immunohistochemical analysis in rats

AIM

The aim of this study was to evaluate the effects of cigarette smoke inhalation (CSI) on inflammation, pro-inflammatory mediators and haematological parameters in rats with induced apical periodontitis (AP).

METHODOLOGY

Thirty-two 3-month-old male Wistar rats were divided into four experimental groups (n = 8): C-Control; S-rats with CSI; AP-rats with AP; and SAP-rats with CSI + AP. Animals in groups S and SAP inhaled cigarette smoke by remaining inside a smoking chamber for 8 min, three times daily, for 50 days. After 20 days of smoke inhalation, animals in AP and SAP groups had the pulps of the lower right first molar exposed to oral environment for 30 days to induce AP. In these subsequent 30 days, animals in group S and SAP continued with CSI. On Day 50, animals were euthanized and mandibles were histologically processed to assess inflammatory infiltrate, immunohistochemical interleukins (IL-1β, IL-6 and TNF-α), and blood samples collected for laboratory analysis. The Mann-Whitney test was performed for non-parametric data and the pairwise analyses of Student's t-test for parametric data, with a significance level of p < .050.

RESULTS

Inflammatory infiltrate was moderate in AP group and more severe in the SAP (p = .010). The interleukins IL-6, IL-1β and TNF-α were higher in SAP group (p < .001) when compared to the AP group. A greater number of red blood cells (p = .010), haemoglobin (p = .007) and neutrophils (p = .014) were observed in the SAP group in comparison with the AP group.

CONCLUSION

Cigarette smoke inhalation induced a more severe inflammatory infiltrate, with increased levels of pro-inflammatory cytokines and changes in haematological parameters in rats with induced AP. Thus, CSI aggravated AP, exacerbating the inflammatory response.

Biocompatibility analysis in subcutaneous tissue and physico-chemical analysis of pre-mixed calcium silicate–based sealers

OBJECTIVES

To evaluate the biocompatibility, physical and chemical properties of three pre-mixed calcium silicate-based sealers and an epoxy resin-based material were assessed. Pre-mixed sealers supposedly obtain water from the root canal moist to hydrate and set.

MATERIALS AND METHODS

Polyethylene tubes were filled with the materials Bio-C Sealer Ion+, Bio-C Sealer, EndoSequence BC Sealer and AH Plus Jet, or left empty and surgically implanted in the subcutaneous tissue of Wistar rats. The animals were euthanised and the tubes and tissue were removed for histological analysis and scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS). Materials' surface chemical characterisation was assessed using Raman spectroscopy and SEM/EDS. Flow, setting time (in two conditions), solubility, radiopacity and pH were also analysed. ANOVA and Bonferroni correction were performed for comparisons (P < 0.05).

RESULTS

Inflammatory response observed in the tissues subsided from 7 to 30 days. Tungsten migration could be detected in the surrounding tissue following AH Plus Jet implantation. All calcium silicate-based sealers exhibited zirconium oxide (radiopacifier) and tricalcium silicate peaks before and after implantation. All materials exhibited flow values above 17 mm. An approximately tenfold difference was observed between the plaster- and metal-mould setting times of the calcium silicate cements indicating its sensitivity to moist variations and solubility above 8% was also observed for these materials.

CONCLUSIONS

Pre-mixed materials exhibited variable setting time and solubility with a decreasing inflammatory response.

CLINICAL RELEVANCE

The variable moist-dependant setting time with high solubility poses a concern for the clinical use of these pre-mixed sealers.

Cell Proliferation, Viability, Differentiation, and Apoptosis of Iron Oxide Labeled Stem Cells Transfected with Lipofectamine Assessed by MRI

To assess in vitro and in vivo tracking of iron oxide labeled stem cells transfected by lipofectamine using magnetic resonance imaging (MRI), rat dental pulp stem cells (DPSCs) were characterized, labeled with iron oxide nanoparticles, and then transfected with lipofectamine to facilitate the internalization of these nanoparticles. Cell proliferation, viability, differentiation, and apoptosis were investigated. Prussian blue staining and MRI were used to trace transfected labeled cells. DPSCs were a morphologically spindle shape, adherent to culture plates, and positive for adipogenic and osteogenic inductions. They expressed CD73 and CD90 markers and lacked CD34 and CD45. Iron oxide labeling and transfection with lipofectamine in DPSCs had no toxic impact on viability, proliferation, and differentiation, and did not induce any apoptosis. In vitro and in vivo internalization of iron oxide nanoparticles within DPSCs were confirmed by Prussian blue staining and MRI tracking. Prussian blue staining and MRI tracking in the absence of any toxic effects on cell viability, proliferation, differentiation, and apoptosis were safe and accurate to track DPSCs labeled with iron oxide and transfected with lipofectamine. MRI can be a useful imaging modality when treatment outcome is targeted.

Participation of fibroblast growth factor-1 and interleukin-10 in connective tissue repair following subcutaneous implantation of bioceramic materials in rats

AIM

To evaluate whether the bioceramic materials Bio-C Pulpo (Bio-C, Angelus) and mineral trioxide aggregate (MTA) Repair HP (MTA-HP, Angelus) induce fibroblast proliferation and release of interleukin-10 (IL-10), an anti-inflammatory cytokine, stimulating connective tissue remodelling. The tissue response of Bio-C and MTA-HP was compared with the White MTA (WMTA; Angelus) since studies have demonstrated that WMTA induces tissue repair.

METHODOLOGY

Bio-C, MTA-HP and WMTA were inserted into polyethylene tubes and implanted in the subcutaneous tissue of Holtzman rats for 7, 15, 30 and 60 days. As a control group (CG), empty tubes were implanted subcutaneously. The number of fibroblasts (FB), Ki-67-, fibroblast growth factor-1- (FGF-1) and IL-10-immunolabelled cells and collagen content in the capsules was obtained. The data were subjected to two-way anova followed by Tukey's test (p ≤ .05).

RESULTS

At 7 days, significant differences in the number of FB were not detected amongst Bio-C, MTA-HP and WMTA groups (p ˃ .05). The capsules of all groups exhibited a significant increase in the number of FB and content of collagen over time. From 7 to 60 days, a significant reduction in the number of FGF-1- and Ki-67-immunolabelled cells was seen in the capsules of all specimens. In all periods, no significant difference in the number of FGF-1-immunolabelled cells was detected between Bio-C and CG specimens. At 60 days, significant differences in the immunoexpression of FGF-1 were not observed amongst the groups. At 7 and 15 days, the highest immunoexpression for Ki-67 was present in Bio-C specimens whilst, after 30 and 60 days, no significant difference was observed amongst the bioceramic materials. At 7 days, few IL-10 immunolabelled cells were present in the capsules of all specimens whereas, at 60 days, a significant increase in the IL-10-immunostaining was present in all groups. At 60 days, the Bio-C, MTA-HP and WMTA groups showed a greater number of IL-10-immunolabelled cells than in the CG specimens (p < .0001).

CONCLUSIONS

Bio-C, MTA-HP and WMTA stimulate fibroblast proliferation, leading to the formation of collagen-rich capsules. FGF-1 and IL-10 may mediate the remodelling of capsules around Bio-C, MTA-HP and WMTA bioceramic materials.

PROBE 2023 guidelines for reporting observational studies in endodontics: Explanation and elaboration

Observational studies play a critical role in evaluating the prevalence and incidence of conditions or diseases in populations as well as in defining the benefits and potential hazards of health-related interventions. There are currently no reporting guidelines for observational studies in the field of Endodontics. The Preferred Reporting Items for study Designs in Endodontology (PRIDE) team has developed and published new reporting guidelines for observational-based studies called the 'Preferred Reporting items for OBservational studies in Endodontics (PROBE) 2023' guidelines. The PROBE 2023 guidelines were developed exclusively for the speciality of Endodontics by integrating and adapting the 'STrengthening the Reporting of OBservational studies in Epidemiology (STROBE)' checklist and the 'Clinical and Laboratory Images in Publications (CLIP)' principles. The recommendations of the Guidance for Developers of Health Research Reporting Guidelines were adhered to throughout the process of developing the guidelines. The purpose of this document is to serve as a guide for authors by providing an explanation for each of the items in the PROBE 2023 checklist along with relevant examples from the literature. The document also offers advice to authors on how they can address each item in their manuscript before submission to a journal. The PROBE 2023 checklist is freely accessible and downloadable from the PRIDE website (http://pride-endodonticguidelines.org/probe/).

Melatonin decreases plasma TNF-α and improves nonenzymatic antioxidant defence and insulin sensitivity in rats with apical periodontitis fed a high-fat diet

AIM

To analyse the effects of melatonin (ME) treatment on oxidative stress and insulin resistance (IR) in rats with apical periodontitis (AP) fed a high-fat diet (HFD).

METHODOLOGY

Eighty 60-day-old rats were divided into eight groups: control (CN), AP, HFD with AP (HFDAP), control with ME (CNME), AP with ME (APME), HFD with ME (HFDME) and HFD with AP+ME (HFDAPME). The animals from the HFD groups were fed a HFD throughout the experimental period. On day 7, the animals from the AP groups were subjected to experimental AP, and after 70 days, the ME groups were treated for 30 days. Glycaemia, insulinaemia, homeostatic model assessment for IR index, tumour necrosis factor-α (TNF-α), and interleukin-6 were analysed in plasma using biochemical tests and enzyme-linked immunosorbent assay. Thiobarbituric acid-reactive substances (TBARS), carbonyl protein (CP), superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione (GSH) and total antioxidant capacity (ferric reducing antioxidant power [FRAP]) were analysed in the gastrocnemius muscle.

RESULTS

(1) Association of AP and HDF exacerbated IR, and ME treatment improved this alteration; (2) AP and HFD and their association showed increased TNF-α, and ME reversed it; (3) TBARS increased in the AP and HFDAP groups, and ME reversed only in the group with the association of disease and diet; (4) CP increased in all HFD groups and improved in the ME groups; (5) GSH activity decreased in all experimental groups, and ME increased this parameter only in the CN and AP groups; (6) FRAP did not change between the groups, but ME treatment increased its activity in the AP and HFD groups; (7) ME increased SOD in the CN and AP groups.

CONCLUSION

Apical periodontitis and HFD promoted IR, and the association of AP with diet promoted IR exacerbation; this resistance might have been caused by an increase in TNF-α. AP promoted more intense changes in lipid oxidative damage than in protein oxidative damage. In non-enzymatic antioxidant defence, it was observed that both AP and HFD and their association promoted a decrease in GSH levels. Overall, ME treatment reversed changes such as oxidative stress and IR.

Biocompatibility and bioactive potential of an experimental tricalcium silicate-based cement in comparison with Bio-C repair and MTA Repair HP materials

AIM

To evaluate the tissue reaction of a tricalcium silicate-based repair material associated with 30% calcium tungstate (TCS + CaWO₄ ) in comparison to Bio-C Repair (Bio-C; Angelus) and to MTA Repair HP (MTA HP; Angelus).

METHODOLOGY

Polyethylene tubes filled with one of the materials or left empty (control group, CG) were implanted into the subcutaneous tissues of rats for 7, 15, 30 and 60 days (n = 32/group). The capsule thickness, number of inflammatory cells, collagen content, interleukin-6 (IL-6), osteocalcin (OCN), von Kossa reaction and analysis under polarized light were evaluated. The data were subjected to generalized linear models for repeated measures, except the OCN. OCN data were submitted to Kruskal-Wallis and Dunn's post hoc test and Friedman followed by Nemenyi's test at significance level of 5%.

RESULTS

At all time points, significant differences in the number of inflammatory cells were not observed between TCS + CaWO₄ and Bio-C, whereas, at 15, 30 and 60 days, no significant difference was detected between TCS + CaWO₄ and MTA HP. At all periods, significant differences were not detected in the number of fibroblasts in TCS + CaWO₄ versus MTA HP, and, at 60 days, no significant difference was demonstrated between these groups and CG. Significant differences in the immunoexpression of IL-6 were not detected amongst bioceramic materials at all periods. From 7 to 60 days, significant reduction in the number of inflammatory cells, number of IL-6-immunopositive cells and in the capsule thickness was accompanied by significant increase in the collagen in all groups. OCN-immunolabelled cells, von Kossa-positive structures and amorphous calcite deposits were observed around all materials, whereas, in the CG, these structures were not seen.

CONCLUSIONS

These findings indicate that the experimental material (TCS + CaWO₄ ) is biocompatible and has a bioactive potential, similar to the MTA HP and Bio-C Repair, and suggest its use as a root repair material.

Early life stress exacerbates bone resorption and inhibits anxiety-like behaviour induced by apical periodontitis in rats

AIM

To evaluate the influence of the early life stress (ELS) on the severity of the apical periodontitis (AP) in Wistar rats.

METHODOLOGY

Forty male Wistar rats were divided into four groups (n = 10): Control rats; AP-rats with AP; ELS-rats subject to ELS; AP + ELS-rats exposed to ELS and subject to AP. ELS was induced by maternal separation (MS) for a period of 3 h for 21 consecutive days. AP was induced via pulp exposure of the first and second right maxillary molars to the oral environment for 40 days. Three days before euthanasia, all rats underwent behavioural analysis to measure anxiety levels by elevated zero maze. Then, the rats were euthanized and the maxillas were removed to assess the occurrence and severity of AP. The periapical region was evaluated for the intensity of the inflammatory infiltrate and the extent of bone loss. The Mann-Whitney test was performed for nonparametric data, and the Tukey's or Student's t-test was performed for parametric data (p < .05).

RESULTS

The intensity of the inflammatory infiltrate was significantly larger in the AP + ELS group when compared with AP group (p < .05). The AP + ELS group exhibited significantly greater alveolar bone loss, with a periapical lesion size of 103.5 ± 29.88, compared with 72.3 ± 22.28 in the AP group (p < .05). Rats with AP displayed higher anxiety-like behaviour in relation to the control group (p < .05). However, exposure to ELS abolished the AP-induced increased anxiety-like 'behaviour' throughout, since that rats from AP + ELS group attended more the open arms than non-stressed rats with AP (p < .05).

CONCLUSION

Early life stress is predictive of the severity of AP exacerbating the inflammatory process and increasing periapical bone resorption.

The effects of gingival blood flow on pulpal blood flow detection using ultrasound Doppler flowmetry: animal study

Objectives

This study evaluated the effect of adjacent gingival blood flow on detection of pulpal blood flow (PBF) using ultrasound Doppler flowmetry (UDF) through animal study.

Materials and Methods

The study included 36 right and left maxillary the third incisors and canines in 9 experimental dogs. The study included 2 main steps: In the first step, the pulse sound level (PSL) was recorded on the cervical part of each tooth without flap elevation (Group 1), with flap elevation (Group 2), and after it was repositioned in place (Group 3). In the second step, the PSL was recorded on the cervical part of each tooth (Group 4), after pulpotomy (Group 5), after partial pulp extirpation (Group 6), after complete extirpation (Group 7), and after canal filling (Group 8). In Groups 5-8, the study was performed with and without flap elevation in the left and right teeth, respectively. The PSL was graded as follows: 0, inaudible; 1, heard faintly; and 2, heard well. The difference between each group was analyzed using Friedman's test with Wilcoxon signed-rank tests (α = 0.05).

Results

In step 1, the PSL results were Group 1 > 2 and 3. In step 2, there was no significant difference between the groups when the flap was not elevated, while PSL results were Group 4 > 5 ≥ 6 and 7 ≥ 8 when the flap was elevated.

Conclusions

PBF is affected by gingival blood flow when measured with UDF. UDF measurements require isolation of gingiva from the tooth.

Gut microbiota may mediate the impact of chronic apical periodontitis on atherosclerosis in apolipoprotein E-deficient mice

AIM

There are growing evidences linking chronic apical periodontitis (CAP) to atherosclerosis. Gut microbiota is found to be involved in the development of atherosclerosis. Recent studies have shown that CAP could change the diversity and composition of the gut microbiota. It was therefore, we hypothesized that gut microbiota and its metabolites could mediate the impact of CAP on atherosclerosis.

METHODOLOGY

Twenty-four 5-week-old lipoprotein E knockout (apoE^-/- ) mice were randomly divided into four groups: the CAP group, Con group, Co-CAP (cohoused with CAP) and Co-Con (cohoused with Con) group. In the CAP group, sterile cotton wool containing P. gingivalis was placed into the exposed pulp chamber, followed by coronal resin-based composite restoration of the bilateral maxillary first and second molars. In the Con group, a sham operation was performed. Biweekly, mice in the CAP group were anaesthetised to check the sealing of coronal access. Meanwhile, the animals in the Con group were anaesthetised. The cohousing approach was used to introduce gut microbiota from the CAP and Con groups into the Co-CAP and Co-Con groups, respectively. Alterations in the abundance and diversity of the gut microbiota were detected using 16S rRNA sequencing, Oil-red O staining was used to demonstrate the extent of lesions, and serum levels of trimethylamine N-oxide (TMAO), and immunohistochemistry of flavin-containing monooxygenase 3 (FMO3) in liver were used to assess TMAO-related metabolic alterations.

RESULTS

Alterations of alpha and beta diversity were shown both in the CAP and the Co-CAP groups. Moreover, the percentage of atherosclerotic lesion area increased in the CAP and Co-CAP groups (p < .05). Linear discriminant analysis effect size (LEfSe) at the family level found the increases of Lachnospiraceae and Ruminococcaceae (p < .05), which were positively correlated with serum TMAO levels (p < .05). In the redundancy analysis technique (RDA), serum levels of TMAO were positively associated with the atherosclerotic lesions. Co-occurrence analysis revealed that the relative abundances of Lachnospiraceae and Porphyromonadacae were positively correlated with both the percentage of lesion area and TMAO level (p < .05).

CONCLUSION

Thus, within the limitations of this study, the data suggest that the gut microbiota can mediate the effects of CAP on atherosclerosis.

A guide to open science practices for animal research

Translational biomedical research relies on animal experiments and provides the underlying proof of practice for clinical trials, which places an increased duty of care on translational researchers to derive the maximum possible output from every experiment performed. The implementation of open science practices has the potential to initiate a change in research culture that could improve the transparency and quality of translational research in general, as well as increasing the audience and scientific reach of published research. However, open science has become a buzzword in the scientific community that can often miss mark when it comes to practical implementation. In this Essay, we provide a guide to open science practices that can be applied throughout the research process, from study design, through data collection and analysis, to publication and dissemination, to help scientists improve the transparency and quality of their work. As open science practices continue to evolve, we also provide an online toolbox of resources that we will update continually.

Open science has become a buzzword in the scientific community that too often misses the practical application for individual researchers. This Essay, provides a guide to choosing the most appropriate tools to make animal research more transparent.

Comparison of EASYDO ACTIVATOR, passive ultrasonic, and needle irrigation techniques on the treatment of apical periodontitis: a study in rats

OBJECTIVES

To evaluate the long-term therapeutic effect of EASYDO ACTIVATOR, passive ultrasonic irrigation, and needle irrigation in experimental apical periodontitis in rats.

MATERIALS AND METHODS

Sprague-Dawley male rats were used to produce periapical lesions. The pulp chambers of the bilaterally first mandibular molars were exposed and left open for 21 days. The rats were divided into four groups according to different irrigation protocols. Seven days after irrigation, the mandibles were removed for micro-CT, histological, and immunohistochemical analysis. Serum levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were assessed by enzyme-linked immunosorbent assays (ELISA). Statistical data were analyzed by one-way analysis of variance (ANOVA) with LSD tests.

RESULTS

The passive ultrasonic irrigation and EASYDO ACTIVATOR groups had the smallest apical lesions compared to the other groups (P < 0.05), while the needle irrigation group had smaller lesions than the control group (P < 0.05). The EASYDO ACTIVATOR group had less inflammation infiltration compared to the control and needle irrigation groups (P < 0.05). The control and needle irrigation groups had more TNF-α expression compared to the passive ultrasonic irrigation and EASYDO ACTIVATOR groups (P < 0.05). The lowest IL-6 expression was observed in the EASYDO ACTIVATOR group. The EASYDO ACTIVATOR group had the lowest serum level of TNF-α than other groups (P < 0.05). IL-6 expression was significantly lower in the EASYDO ACTIVATOR group in comparison with the control and needle irrigation groups (P < 0.05).

CONCLUSIONS

EASYDO ACTIVATOR can significantly reduce the apical lesions and decrease the inflammatory response around the periapical area.

CLINICAL RELEVANCE

EASYDO ACTIVATOR is recommended for clinical application.

Curcumin reduces inflammation in rat apical periodontitis

AIM

To evaluate the effect of systemic curcumin administration on the severity of apical periodontitis (AP).

METHODOLOGY

Forty male Wistar rats weighing 250-280g each, age 2.5 months, were distributed into four groups (n=10): control untreated rats (C), control rats treated with curcumin (CUR), rats with pulp exposure-induced apical periodontitis (AP), and rats with pulp exposure-induced apical periodontitis treated with curcumin (AP-CUR). Curcumin treatment was administered orally once daily for 15 days before pulp exposure and continued for 30 days after pulp exposure. The rats were sacrificed at 30 days, and the jaws were collected and reconstructed in a program specific for micro-CT. The jaws were processed for analysis of the inflammatory process using Haemotoxylin and Eosin staining and immunohistochemical assays for interleukin tumour necrosis factor alpha (TNF-α), interleukin (Il)-6, and Il-1β. Tartrate-resistant acid phosphatase (TRAP) and osteocalcin (OCN) staining were used to analyze the resorptive process on the bone surface of periapical area. Kruskal-Wallis with Dunn's test was performed for nonparametric data, and ANOVA with Tukey's test for parametric data, p < .05.

RESULTS

Micro-CT revealed no statistically significant differences in bone resorption between the AP and AP-CUR groups (p > .05). The levels of inflammatory cell infiltration and immunoreactivity for the proinflammatory cytokines TNF-α, Il-6, and Il-1β were significantly higher in the periapical lesions of the AP group than in the AP-CUR group (p < .05). The number of TRAP-positive multinucleated cells was higher in the AP group than in the AP-CUR group (p < .05). In OCN-positive cells, no differences were observed between the AP and AP-CUR groups (p > .05).

CONCLUSIONS

Oral supplementation with curcumin had a significant effect on the AP severity in rats, suggesting an anti-inflammatory effect of curcumin on AP development.

Laboratory study of tissue repair of resin-based endodontic sealers in critical surgical defects

Filling materials should be restricted to the root canal space. However, sometimes it is impossible to control the apical extrusion, in this case, the fate of the filling material and the result of the treatment will depend on its physicochemical properties and biocompatibility.

Influence of supplement administration of omega-3 on the subcutaneous tissue response of endodontic sealers in Wistar rats

AIM

Natural substances such as omega-3 have been used in the medical field due to their numerous properties and, in particular, modulating effect on the systemic and local inflammatory processes. Thus, this study evaluated the influence of omega-3 supplementation on the subcutaneous tissue response of endodontic sealers in Wistar Rats.

METHODOLOGY

Polyethylene tubes were implanted in the subcutaneous tissue of 48 animals (one empty for control and three filled with Sealapex, AH Plus or Endofill). The animals were treated with omega-3 (TO) or water (TW). Treatments started 15 days before implantation until euthanasia. After 5, 15 and 30 days (n = 8), animals were euthanized and polyethylene tubes and surrounding tissue were removed and processed for histological analysis. The inflammatory reaction was analysed by Haematoxylin and Eosin stain and immunolabelling for IL-6 and TNF-α. The collagen maturity was analysed by picrosirius red stain and calcium deposition by von Kossa stain and polarized light. Results were statistically analysed (p < .05).

RESULTS

Amongst TW sealer groups, Endofill evoked a more intense inflammatory infiltrate compared with AH Plus and control in the 30-day period (p = .009). However, in TO sealer groups, there was no difference amongst the sealers and control in all periods (p > .05). Comparing each sealer as a function of the supplementation with water or omega-3, there are differences for Endofill (p = .001) and Sealapex (p = .005) in the 30-day period, presenting lower inflammatory infiltrate in the animals treated with omega-3. A higher percentage of immature fibres was observed at 15 and 30 days in the TO group, compared with the TW group (p < .05). The deposition of calcium particles was observed only by Sealapex in all periods, despite the supplementation procedure.

CONCLUSIONS

Omega-3 supplementation influence the tissue reactions of endodontic sealers, modulating inflammation, the immunolabelling of IL-6 and TNF-α, the repair process and it does not interfere with calcium deposition.

Effect of systemic antibiotic therapy on pulp repair following extrusive luxation and avulsion in a murine model: A histomorphological study

BACKGROUND/AIM

The evidence for any benefit of systemic antibiotic therapy on pulp survival following extrusive luxation and avulsion is inconclusive. The aim of this study was to evaluate the effect of systemic antibiotic therapy with amoxycillin and tetracycline for 7 days on different aspects of dental pulp repair in a murine model.

MATERIAL AND METHODS

The right maxillary incisor of 180 4 to 8-week-old male Wistar rats underwent extrusive luxation or avulsion. The animals were then treated with saline solution (control), tetracycline, or amoxicillin administered intra-gastrically for 7 days, and euthanized at 7, 15, and 30 days post-operatively. The layer of odontoblast cells, reparative dentin deposition, Hertwig's epithelial root sheath, pulp necrosis, and periapical inflammatory infiltrate were histomorphologically analyzed and scored. Mann-Whitney, Kruskal-Wallis, and Dunn tests were used to compare mean scores for the different procedures, treatments, and times (p ≤ .05).

RESULTS

Significant differences were observed between luxated and avulsed teeth (p < .05). In luxated teeth, no differences were observed among treatments and times, except for more tertiary dentin deposition in the coronal third with the use of tetracycline compared with amoxicillin at 15 days (p < .05). In avulsed teeth, higher scores for the layer of odontoblast cells and lower scores for periapical inflammatory infiltrate at 7 days and pulp necrosis at 7 and 15 days were observed in the amoxicillin group compared to the saline and tetracycline groups (p < .05). At 30 days, however, no differences were observed among treatments.

CONCLUSIONS

The use of systemic antibiotic therapy with tetracycline or amoxicillin for 7 days did not contribute to pulp repair following extrusive luxation or avulsion in rats. However, the results warrant further research into the use of amoxicillin for a more extended period of time in cases of avulsion.

A critical analysis of research methods and experimental models to study pulpitis

Pulpitis is the inflammatory response of the dental pulp to a tooth insult, whether it is microbial, chemical, or physical in origin. It is traditionally referred to as reversible or irreversible, a classification for therapeutic purposes that determines the capability of the pulp to heal. Recently, new knowledge about dental pulp physiopathology led to orientate therapeutics towards more frequent preservation of pulp vitality. However, full adoption of these vital pulp therapies by dental practitioners will be achieved only following better understanding of cell and tissue mechanisms involved in pulpitis. The current narrative review aimed to discuss the contribution of the most significant experimental models developed to study pulpitis. Traditionally, in vitro two(2D)- or three(3D)-dimensional cell cultures or in vivo animal models were used to analyse the pulp response to pulpitis inducers at cell, tissue or organ level. In vitro 2D cell cultures were mainly used to decipher the specific roles of key actors of pulp inflammation such as bacterial by-products, pro-inflammatory cytokines, odontoblasts or pulp stem cells. However, these simple models did not reproduce the 3D organisation of the pulp tissue and, with rare exceptions, did not consider interactions between resident cell types. In vitro tissue/organ-based models were developed to better reflect the complexity of the pulp structure. Their major disadvantage is that they did not allow the analysis of blood supply and innervation participation. On the contrary, in vivo models have allowed researchers to identify key immune, vascular and nervous actors of pulpitis and to understand their function and interplay in the inflamed pulp. However, inflammation was mainly induced by iatrogenic dentine drilling associated with simple pulp exposure to the oral environment or stimulation by individual bacterial by-products for short periods. Clearly, these models did not reflect the long and progressive development of dental caries. Lastly, the substantial diversity of the existing models makes experimental data extrapolation to the clinical situation complicated. Therefore, improvement in the design and standardization of future models, for example by using novel molecular biomarkers, databased models and artificial intelligence, will be an essential step in building an incremental knowledge of pulpitis in the future.

Hsa-miRNA-143-3p regulates the odontogenic differentiation of human stem cells from the apical papilla by targeting NFIC

AIM

To evaluate the effects of hsa-miRNA-143-3p on the cytodifferentiation of human stem cells from the apical papilla (hSCAPs) and the post-transcriptional regulation of Nuclear factor I-C (NFIC).

METHODOLOGY

miRNA expression profiles in human immature permanent teeth and during hSCAP differentiation were examined. hSCAPs were treated with miR-143-3p overexpression or silencing viruses, and the proliferation and odontogenic and osteogenic differentiation of these stem cells, and the involvement of the NFIC pathway, were investigated. Luciferase reporter and NFIC mutant plasmids were used to confirm NFIC mRNA as a direct target of miR-143-3p. NFIC expression analysis in the miR-143-3p overexpressing hSCAPs was used to investigate whether miR-143-3p functioned by targeting NFIC. Student's t-test and chi-square tests were used for statistical analysis.

RESULTS

miR-143-3p expression was screened by microarray profiling and was found to be significantly reduced during hSCAP differentiation (p < .05). Overexpression of miR-143-3p inhibited the mineralization of hSCAPs significantly (p < .05) and downregulated the levels of odontogenic differentiation markers (NFIC [p < .05], DSP [p < .01] and KLF4 [p < .01]), whereas silencing of miR-143-3p had the opposite effect. The luciferase reporter gene detection and bioinformatic approaches identified NFIC mRNA as a potential target of miR-143-3p. NFIC overexpression reversed the inhibitory effect of miR-143-3p on the odontogenic differentiation of hSCAPs.

CONCLUSIONS

miR-143-3p maintained the stemness of hSCAPs and modulated their differentiation negatively by directly targeting NFIC. Thus, inhibition of this miRNA represents a potential strategy to promote the regeneration of damaged tooth roots.