Relationship between apical periodontitis and atherosclerosis in rats: lipid profile and histological study

Lifestyle, caries, and apical periodontitis: Results from a university-based cross-sectional study

AIM

Lifestyle factors significantly influence the development of inflammatory diseases, and emerging evidence suggests they may also impact oral health. However, no studies have explored their role in apical periodontitis (AP) amongst adults. This study aimed to assess the association between adherence to the Mediterranean diet (MD), physical activity, perceived stress, and sleep quality with the periapical and caries status in a university-based cohort.

METHODOLOGY

A total of 149 periodontally healthy patients were included in the study. Clinical assessments and radiographic examinations [Orthopantomography (opt) and periapical radiographs] were conducted to evaluate the periapical status. Data on their periapical index (PAI) score and the decayed, missing and filled teeth (DMFT) index were recorded. Validated questionnaires were used to investigate patient's lifestyles. A final logistic regression model was performed for the multivariable analysis to evaluate the predictive ability of adherence to Mediterranean lifestyle on the presence of AP; other local, systemic and environmental factors were included as independent factors in the model.

RESULTS

Significant associations were observed between AP and high/low adherence to the MD (p = .00), high/low-moderate physical activity (p = .00), high/low sleep quality (p = .00) and high/low perceived stress (p = .00). The final multivariable regression model showed that low adherence to MD (OR = 3.68; 95% confidence interval [CI]: 1.24-10.83; p = . 01) and reduced sleep quality (OR = 3.04; 95% CI: 1.42-6.50; p = .00) were identified as potential risk factors for AP development. On the other hand, the DMFT index showed no significant association with lifestyle factors (OR = 1.0; CI: 1.01-1.14; p = .02) but was correlated with the development of AP (OR = 1.07; CI: 1.01-1.14; p = .02).

CONCLUSION

Results from the present study suggest a potential association between low adherence to MD and reduced sleep quality with the development of AP. Individuals with low adherence to MD and inadequate sleep quality faced respectively 4-fold and 3-fold increased odds of developing periapical lesions. Further research is essential to elucidate the causal mechanisms underlying these associations and to determine whether lifestyle adjustments could improve endodontic success rate.

Metabolic syndrome and its effect on immune cells in apical periodontitis- a narrative review

OBJECTIVES

Apical periodontitis (AP) is an inflammatory immune response in periapical tissues caused by microbial infections. Failure of root canal treatment or delayed healing is often due to intracanal or extra-radicular bacteria. However, beyond microbial factors, the patient's systemic health can significantly influence the progression and healing of AP. Metabolic syndrome is a risk factor and it is characterized by a cluster of interconnected metabolic risk factors, including abdominal obesity, hyperlipidemia, hypertension, and hyperglycemia.

MATERIALS AND METHODS

A comprehensive literature review was conducted on apical periodontitis and metabolic syndrome, and their impact on the roles of different immune cell populations.

RESULTS

Both AP and metabolic syndrome are inflammatory diseases that involve complex and interwoven immune responses. The affected immune cells are categorized into the innate (neutrophils, macrophages, and dendritic cells) and adaptive immune systems (T cells and B cells).

CONCLUSIONS

Metabolic diseases and AP are closely correlated, possibly intertwined in a two-way relationship driven by a shared dysregulated immune response.

CLINICAL RELEVANCE

Understanding the pathophysiology and immune mechanisms underlying the two-way relationship between metabolic syndrome and AP can help improve treatment outcomes and enhance the overall well-being of patients with endodontic disease complicated by metabolic syndrome.

Mono-species bacteria-induced chronic apical periodontitis triggers the aortic inflammatory response via modulation of systemic inflammation and lipid metabolism

Cardiovascular disease (CVD) is the leading cause of death worldwide and has been confirmed to be associated with a common oral bacterial infection-chronic apical periodontitis (CAP). However, the detailed mechanisms remain controversial. CAP can potentially alter systemic inflammation, lipid metabolism, and gut microbiota, all of which contribute to the progression of the aortic inflammatory response. This study aimed to explore the differential effects between E. faecalis and P. gingivalis-CAP on the aortic inflammatory response, which focused on changes in systemic inflammation, lipid metabolism, and gut microbiota, to explore potential mechanisms linking oral disease to CVD. Our result showed P. gingivalis-CAP could activate more serious aortic inflammatory cytokine mRNA expression (TNF-α, MCP-1, and ICAM-1) than E. faecalis-CAP by promoting higher serum inflammation (TNF-α, IL-6, IL-1α, and MCP-1) and lipid (LDL-C and TC) level. Simultaneously, there was no significant change in gut microbiota between them. Furthermore, all serum inflammatory cytokines showed substantial correlations with aortic inflammatory cytokine mRNA expression, and certain serum lipid indicators showed significant correlations, but only two gut microorganisms (Ruminococcaceae and Prevotellaceae) showed significant correlations. The combined results suggest that CAP might activate the aortic inflammatory response in association with changes in the three potential mechanisms. However, the promotion of gut microbiota might be relatively weak. Using experimental CAP induced by specific bacteria, in which bacteria are sequestered in the medullary cavity, avoids the direct influence of blood or intestinal pathways, and provides new perspectives for studying the mechanism of CVD associated with oral disease. Overall, these findings suggest that CAP may exacerbate systemic inflammation and serum lipid levels in patients with CVD, highlighting the importance of educating such patients on oral hygiene.

Increase Toll-like receptors 2 and 4 in apical periodontitis of rats with chronic liver disease

The aim of this study was to evaluate the influence of liver fibrosis (LF) on the expression of Toll-like receptors (TLR) 2 and 4 in apical periodontitis (AP) in Wistar rats. Forty Wistar rats were allocated in the following groups (n = 10): C-control; AP-apical periodontitis; LF-liver fibrosis; AP + LF-rats with AP and LF. LF and AP were induced by established methodologies. Histological, bacteriological, and immunohistochemical analyses were performed according to pre-established scores. For comparisons between AP and AP + LF groups, the Mann-Whitney test was used (P < .05). The livers of the LF and AP + LF groups showed generalized portal inflammatory infiltrate and collagen fibers confirming the presence of LF. Histopathological analysis in the maxilla of the AP + LF group showed areas of necrosis comprising the entire dental pulp and periapical tissue surrounded by a more intense inflammatory infiltrate than observed in the AP group (P = 0.032). A significant number of specimens in the AP + LF group showed microorganisms beyond the apical foramen adhered to the extraradicular biofilm, demonstrating greater invasion compared to the AP group (P = .008). Immunohistochemical analysis showed a large number of cells immunoreactive for TLR2 and TLR4 in the AP + LF group, compared to the AP group (P < 0.05). Liver fibrosis favors the inflammation and contamination of microorganisms in apical periodontitis and triggers the expression of TLR2 and TLR4, modulating innate immunity response in periapical lesions.

Biochemical, pathohistological, radiographic and cardiological analysis reveals the possible association between apical periodontitis and cardiac function in diabetic rats

OBJECTIVE

To evaluate the possible effects of apical periodontitis (AP) on cardiac function, structure, and oxidative stress (OS) in rats with diabetes mellitus type 2 (T2DM).

DESIGN

Forty-eight (Wistar albino, male) rats were randomized into four groups: control healthy (CTRL), normoglycemic with AP (AP), T2DM, and T2DM with AP (T2DM+AP). T2DM was induced by streptozotocin and a high-fat diet. AP was induced by pulp exposure to the oral environment for 4 weeks and analyzed radiographically. In the blood samples insulin and glucose were established. In vivo, cardiac function was evaluated by echocardiography. Ex vivo cardiac function was assessed by the Langendorff technique. Heart tissue was analyzed pathophysiologically. OS was determined in cardiac tissue homogenate and coronary venous effluent, spectrophotometrically.

RESULTS

Impaired glycoregulation was observed in the T2DM+AP group compared to the T2DM, AP, and CTRL groups. The T2DM+AP group was associated with disturbed echocardiography and cardiodynamic parameters. The levels of superoxide anion radical, nitrite, and index of lipid peroxidation were significantly increased, while the superoxide dismutase and catalase were significantly decreased in the T2DM+AP group compared to T2DM, AP, and CTRL groups. The radiographic AP area was significantly larger in the T2DM+AP compared to the AP group.

CONCLUSION

AP was associated with increased glucose levels, impaired cardiac function, structure, and OS in diabetic rats. Diabetes was related to an increased radiographic AP area. The study may be a starting point for further research to clarify the effects of AP on cardiac function in various models of systemic diseases.

Apical Periodontitis and Systemic Health: A Bibliometric Analysis of the Top 100 Most-cited Publications

INTRODUCTION

Bibliometric analysis quantitatively measures the impact of scientific articles within their respective fields, with citation counts being a key indicator of influence. This study aimed to identify the top 100 most-cited articles related to apical periodontitis and systemic health, analyzing their main characteristics.

METHODS

The top 100 most-cited articles were identified using Web of Science. Data on publication year, citations, title, authors, institutions, countries, journal impact factor, study design, keywords, and open access status were extracted. VOSviewer software analyzed author and keyword networks, while Power BI evaluated international collaborations, study design, and citations. Poisson regression was performed in R software (P < .05).

RESULTS

We reviewed 1,141 studies and selected the top 100 most-cited articles, totaling 4,744 citations (4,005 excluding self-citations), with an average of 47.44 citations per article. The most-cited article, a 2015 review by Segura-Egea JJ, had 187 citations. The highest publication activity was in 2017 and 2019 (n = 13). Leading institutions were the University of Sevilla and São Paulo State University. Europe accounted for 41% of publications and 2,251 citations, followed by Latin America and the United States. Cross-sectional studies were the most common (18%), with systemic diseases, particularly coronary heart disease and diabetes mellitus, as dominant topics. Most articles (69%) were published in journals with an impact factor above 3, with the Journal of Endodontics leading in number of articles.

CONCLUSIONS

This bibliometric review highlights the increasing research interest in the relationship between apical periodontitis and systemic health, with most contributions coming from Europe and Latin America.

Correlation Between Proinflammatory Cytokine Expression and Clinical Data in Apical Granuloma

INTRODUCTION

This study was intended to evaluate the expression of inflammatory cytokines commonly secreted by CD4+ T cells (IL-2, IL-5, IL-17, TGF-β, TNF-α, and IFN-γ) in apical granulomas and correlate with the clinical conditions and time elapsed since root canal treatment.

METHODS

Eighteen biopsy specimens obtained by periradicular surgery of teeth with post-treatment apical periodontitis and diagnosed as apical granuloma were available from the oral pathology laboratory. Silanized slides containing paraffin sections were used for immunohistochemical reactions. Images were analyzed by using an optical microscopy and each slide was subdivided into 5 fields at high magnification.

RESULTS

IFN-γ and TGF-β were the cytokines with the highest expression levels. There were statistically significant differences when comparing IL-2 and IFN-γ (P < .05), and IL-2 and TGF-β (P < .05). Comparison between the detected cytokines and clinical data and time of treatment demonstrated significant correlation (P < .05) between lower expression of IL-2 and the presence of painful symptoms, absence of sinus tract, and treatments performed more than 4 years before. It was also possible to observe a significant correlation between lower expression of IL-5 and treatments performed less than 4 years before (P < .05).

CONCLUSION

IFN-γ and TGF-β were highly expressed in apical granulomas. However, only IL-2 and IL-5 levels were associated with clinical data and time since previous root canal treatment.

Experimental apical periodontitis alters salivary biochemical composition and induces local redox state disturbances in the salivary glands of male rats

OBJECTIVES

The objective was to evaluate the effects of experimental apical periodontitis on the inflammatory, functional, biochemical, and redox parameters of the parotid and submandibular glands in rats.

MATERIALS AND METHODS

Twenty 12-week-old male Wistar rats were randomly divided into two groups (n = 10): a control group and apical periodontitis group. After 28 days, the saliva was collected for salivary flow rate and biochemistry composition. Both glands were sampled for quantification of the tumor necrosis factor-alpha (TNF-α) and biochemical analyses of redox state.

RESULTS

TNF-α concentrations were higher in both salivary glands adjacent to the periapical lesions in animals with apical periodontitis and also compared to the control group. The apical periodontitis group increased the salivary amylase, chloride, potassium, calcium, and phosphate. The total oxidant capacity increased in the parotid gland adjacent to the periapical lesions in the same rat and compared to the control group. Conversely, the total antioxidant capacity of the parotid glands on both sides in the apical periodontitis group was lower than that in the control group. Furthermore, glutathione peroxidase activity increased in the submandibular gland adjacent to the apical periodontitis group compared to the control group.

CONCLUSIONS

Experimental apical periodontitis alters salivary biochemical composition, in addition to increasing inflammatory marker and inducing local disturbances in the redox state in the parotid and submandibular glands of male rats.

CLINICAL RELEVANCE

Apical periodontitis could exacerbate the decline in oral health by triggering dysfunction in the salivary glands.

The possible role of Gremlin1 in inflammatory apical periodontitis

OBJECTIVE

In this study, we investigated the involvement of Gremlin1 on the pathological process of apical periodontitis and detect the underlying mechanisms preliminarily.

METHODS

Clinical healthy and inflamed periapical specimens were collected. Then, apical periodontitis (AP) animal models were established by consistent pulp exposure. In addition, AAV-shGremlin1 was injected into inflamed periapical lesions to inhibit the expression of Gremlin1. Alveolar bone loss was measured by Micro-CT. Furthermore, immunohistochemical or immunofluorescence staining of Gremlin1, phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β were performed.

RESULTS

The expression of Gremlin1 is markedly increased in periapical lesions not only in clinic samples but also in animal models. Moreover, in rats' AP model, we uncovered that the Gremlin1 protein expression levels in apical lesions is positively correlated with those of IL-1β. Besides, the blockade of Gremlin1 in periapical lesions could substantially suppress the alveolar bone loss and restrains the inflammatory status by impacting the activation levels of phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β.

CONCLUSIONS

Taken together, these results illustrated that Gremlin1 acts as a crucial mediator and possibly serves as a potential diagnostic marker for periapical periodontitis. Discovery of new factors involved in the pathophysiology of periapical periodontitis could contribute to the development of novel therapeutic treatment for the disease.

Ferroptosis of macrophages facilitates bone loss in apical periodontitis via NRF2/FSP1/ROS pathway

Apical periodontitis (AP) is an infectious disease that causes periapical tissue inflammation and bone destruction. Ferroptosis, a novel type of regulated cell death, is closely associated with inflammatory diseases and the regulation of bone homeostasis. However, the exact involvement of ferroptosis in the bone loss of AP is not fully understood. In this study, human periapical tissues were collected, and a mouse model was established to investigate the role of ferroptosis in AP. Colocalization staining revealed that ferroptosis in macrophages contributes to the inflammatory bone loss associated with AP. A cell model was constructed using RAW 264.7 cells stimulated with LPS to further explore the mechanism underlying ferroptosis in macrophages upon inflammatory conditions, which exhibited ferroptotic characteristics. Moreover, downregulation of NRF2 was observed in ferroptotic macrophages, while overexpression of NRF2 upregulated the level of FSP1, leading to a reduction in reactive oxygen species (ROS) in macrophages. Additionally, ferroptotic macrophages released TNF-α, which activated the p38 MAPK signaling pathway and further increased ROS accumulation in macrophages. In vitro co-culture experiments demonstrated that the osteogenic ability of mouse bone marrow stromal cells (BMSCs) was suppressed with the stimulation of TNF-α from ferroptotic macrophages. These findings suggest that the TNF-α autocrine-paracrine loop in ferroptotic macrophages can inhibit osteogenesis in BMSCs through the NRF2/FSP1/ROS signaling pathway, leading to bone loss in AP. This study highlights the potential therapeutic value of targeting ferroptosis in the treatment of inflammatory bone diseases.

Modulatory influence of melatonin on apical periodontitis in Wistar rats fed a high-fat diet

OBJECTIVE

This study aimed to evaluate the influence of high-fat diet (HFD) and melatonin (MEL) treatment on the progression of inflammation and alveolar bone resorption (ABR) in rats with AP.

DESIGN

Forty male Wistar rats were divided into four groups: apical periodontitis (AP), HFDAP, APMEL and HFDAPMEL. The animals were fed an HFD or standard diet for 107 days. On the 7th day, the rats were subjected to AP, and after 70 days, the rats in the MEL groups were treated with MEL for 30 days. Post treatment, the animals were euthanized, and their jaws were retrieved for evaluation of bone resorption, intensity of the inflammatory response, and immunohistochemical analysis including tartrate-resistant acid phosphatase (TRAP) and interleukin-1β (IL-1β) levels and tumor necrosis factor (TNF)-α expression.

RESULTS

The APMEL group showed reduction in the inflammatory infiltrate and IL-1β expression relation to HFDAP, while the TNF-α levels did not differ among the groups. The HFDAP group showed an increase in the ABR. MEL reduced the TRAP levels in the APMEL and HFDAPMEL groups.

CONCLUSIONS

while MEL could reduce TRAP levels in the APMEL and HFDAPMEL groups, the reduction in the HFDAPMEL group was smaller than that in the APMEL group, demonstrating that the interaction between AP and HFD decreased the anti-resorptive effects of MEL.

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.

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.

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.

Chronic apical periodontitis exacerbates atherosclerosis in apolipoprotein E-deficient mice and leads to changes in the diversity of gut microbiota

Aim

To investigate the impact of chronic apical periodontitis (CAP) on atherosclerosis and gut microbiota by establishing a Porphyromonas gingivalis (P. gingivalis)‐induced CAP in an apolipoprotein E‐deficient (apoE^−/−) mice model.

Methodology

Twenty‐eight male apoE^−/− mice were divided into two groups with 14 in each: CAP group and control group. In the CAP group, sterile cotton wool containing 10⁸ colony‐forming units of P. gingivalis was placed into the pulp chamber after pulp exposure followed by coronal resin filling in bilateral maxillary first and second molars. The mice were fed with a chow diet to induce atherosclerosis. Animals were euthanized 16 weeks after the operation, and the periapical lesions of bilateral maxillary first and second molars were assessed by micro‐CT. After collection of aortic arches, atherosclerotic lesions were measured by Oil Red O staining. Serum levels of high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C), total cholesterol (TC), and triglycerides (TG) were measured. Stools were collected to detect alterations in gut microbiota by 16S rRNA gene sequencing. Independent samples t‐test was used to calculate the difference between the two groups.

Results

CAP was observed in 98.2% of molars. A significant increase in atherosclerotic plaque formation in the aortic arches was found in the CAP groups (CAP: 2.001% ± 0.27%, control: 0.927% ± 0.22%, p = .005). No significant difference was observed between sevum level of HDL‐C (CAP: 2.295 ± 0.31 mmol/L, Control: 3.037 ± 0.55 mmol/L, p = .264) or LDL‐C (CAP: 17.066 ± 3.95 mmol/L, Control: 10.948 ± 1.69 mmol/L, p = .177) in CAP group and Control group. There were no significant differences in TG (CAP: 1.076 ± 0.08 mmol/L, control: 1.034 ± 0.13 mmol/L, p = .794) or TC (CAP: 6.372 ± 0.98 mmol/L, control: 6.679 ± 0.75 mmol/L, p = .72) levels between the two groups (p > .05). The alpha diversity was elevated in the CAP group. In terms of beta diversity, the CAP and control groups were clearly distinguished by the microbial community.

Conclusion

In a mouse experimental model, pulp infection with P. gingivalis ‐induced CAP, thus aggravating the development of atherosclerosis. Meanwhile, CAP increased alpha diversity and altered the beta diversity of the gut microbiota.

Effect of butyrate, a bacterial by-product, on the viability and ICAM-1 expression/production of human vascular endothelial cells: Role in infectious pulpal/periapical diseases

AIM

To investigate the effects of butyric acid (BA), a metabolic product generated by pulp and root canal pathogens, on the viability and intercellular adhesion molecule-1 (ICAM-1) production of endothelial cells, which are crucial to angiogenesis and pulpal/periapical wound healing.

METHODOLOGY

Endothelial cells were exposed to butyrate with/without inhibitors. Cell viability, apoptosis and reactive oxygen species (ROS) were evaluated using an MTT assay, PI/annexin V and DCF fluorescence flow cytometry respectively. RNA and protein expression was determined using a polymerase chain reaction assay and Western blotting or immunofluorescent staining. Soluble ICAM-1 (sICAM-1) was measured using an enzyme-linked immunosorbent assay. The quantitative results were expressed as mean ± standard error (SE) of the mean. The data were analysed using a paired Student's t-test where necessary. A p-value ≤0.05 was considered to indicate a statistically significant difference between groups.

RESULTS

Butyrate (>4 mM) inhibited cell viability and induced cellular apoptosis and necrosis. It inhibited cyclin B1 but stimulated p21 and p27 expression. Butyrate stimulated ROS production and hemeoxygenase-1 (HO-1) expression as well as activated the Ac-H3, p-ATM, p-ATR, p-Chk1, p-Chk2, p-p38 and p-Akt expression of endothelial cells. Butyrate stimulated ICAM-1 mRNA/protein expression and significant sICAM-1 production (p < .05). Superoxide dismutase, 5z-7oxozeaenol, SB203580 and compound C (p <  .05), but not ZnPP, CGK733, AZD7762 or LY294002, attenuated butyrate cytotoxicity to endothelial cells. Notably, little effect on butyrate-stimulated sICAM-1 secretion was found. Valproic acid, phenylbutyrate and trichostatin (three histone deacetylase inhibitors) significantly induced sICAM-1 production (p < .05).

CONCLUSION

Butyric acid inhibited proliferation, induced apoptosis, stimulated ROS and HO-1 production and increased ICAM-1 mRNA expression and protein synthesis in endothelial cells. Cell viability affected by BA was diminished by some inhibitors; however, the increased sICAM-1 secretion by BA was not affected by any of the tested inhibitors. These results facilitate understanding of the pathogenesis, prevention and treatment of pulpal/periapical diseases.

Impact of endodontic and periodontal diseases and treatments on the aorta and liver of obese and non-obese rats

AIM

To evaluate the impact of the presence and treatment of periodontal disease (PD) and apical periodontitis (AP) on the aorta and liver of obese and non-obese rats.

METHODOLOGY

One hundred and forty Wistar rats were divided into two groups, according to the diet administered: normal diet (-n), without obesity; and cafeteria diet (-c), with induced obesity. These groups were divided into seven subgroups according to the specific experimental protocols: naïve control (NC); AP; AP with treatment (APt); PD; PE with treatment (PDt); AP and PD (APPD); and AP and PD with treatment (APPDt). AP and PD lesions were induced for four weeks. Four weeks after treatments, the animals were euthanatized, and the aorta and liver were dissected for histological evaluation. For the comparison of the thickness of the aorta between groups, the Kruskal-Wallis test was used, followed by the Mann-Whitney test. For the analysis of other variables related to the aorta and liver outcomes, logistic regression was carried out.

RESULTS

Both PD and AP were associated with the development of histological alterations in the aortic arch, with no significant difference between obese and non-obese animals (p = .17). The aorta thickness was increased significantly (p < .05) with the combination of PD and AP in obese rats (APPDt-c group) compared with the other groups (NC-n, APt-n, APt-c and AP-c). The logistic regression models revealed that the untreated (OR = 7.78; 95%CI = 2.4-25) and treated (OR = 2.9; 95%CI = 1.0-8.4) groups were significantly more likely to have endothelial alterations compared with the control groups (p = .002). Obesity (OR = 16.5; 95%CI = 3.4-81.3) was the only predictor variable of liver steatosis (p < .001).

CONCLUSION

Histological alterations in the aortic arch of obese and non-obese rats were observed in the presence of periodontal disease and apical periodontitis. The combination of PD and AP increased the aorta thickness in obese rats. A reduction of vascular endothelial lesions was observed with the treatments of PD and AP.

Evolution of endodontic medicine: a critical narrative review of the interrelationship between endodontics and systemic pathological conditions

Endodontics has gained emphasis in the scientific community in recent years due to the increase in clinical and in animal models studies focused on endodontic medicine, which aims to evaluate the interrelationship between systemic and periapical tissues pathological conditions. These studies have shown that systemic changes can boost the pathogenesis of endodontic infection, favoring its development and progression. A contrary relationship is reported in numerous studies that affirm the potential of endodontic infection to trigger systemic damage and may lead to the worsening of pre-existing pathologies. Recently, the potential of filling materials to develop systemic changes such as neurological alterations had been evaluated, also showing that systemic diseases can negatively influence tissue responses to filling materials after endodontic treatment. Despite advances in endodontic medicine studies, there are still gaps in knowledge on the mechanisms of interactions between apical periodontitis (AP) and systemic diseases and much research to be done. In this sense, this critical narrative literature review aimed to show the evolution of studies in endodontic medicine to help the endodontist to know the role of systemic diseases in the pathogenesis of AP and the possible interference in the repair of periapical tissues after endodontic treatment, as well as to evidence the systemic complications that can be triggered or aggravated in the presence of endodontic infection.

Cardiac, biochemical and histopathological analysis reveals impaired heart function in hypertensive rats with apical periodontitis

AIM

To investigate the association between experimentally induced apical periodontitis (AP) and heart function in hypertensive rats.

METHODOLOGY

Forty-eight normotensive Wistar albino and spontaneously hypertensive (SHR) rats were divided into four equal groups: control (C), normotensive with AP (AP), SHR and SHR with AP (SHR + AP). AP was induced on the first right mandibular molars by exposing the pulp chambers to the oral environment for four weeks and confirmed radiographically. Thereafter, the animals were sacrificed by cervical dislocation, whilst hearts were isolated and perfused according to the Langendorff technique gradually increasing coronary perfusion pressures 40-120 cmH₂ O. The hemimandibles were analysed radiographically (mm² and pixels) to verify the presence of AP. Biomarkers of cardiac oxidative stress (OS) were determined in coronary venous effluent and cardiac tissue homogenate. Cardiac tissue was analysed histopathologically for signs of heart damage (oedema, fibrosis and necrosis). All data were analysed by Kruskal-Wallis and one-way anova tests (p < .05).

RESULTS

The levels of the maximum left ventricular pressure development rate of the SHR + AP group were significantly increased compared to the AP and C groups, and of the SHR group compared with the C group (p < .05). The levels of the minimum left ventricular pressure development rate of the SHR + AP group were significantly decreased compared to the AP, SHR and C groups, and of the SHR group compared to the C group (p < .05). The radiographic AP area was significantly larger in the SHR + AP group than in the AP group (p < .01). The levels of superoxide anion were significantly higher in the SHR + AP group than in the AP, SHR and C groups (p < .05). The activities of superoxide dismutase in cardiac tissue homogenate were significantly lower in the SHR + AP and AP groups compared with the SHR and C groups (p < .05).

CONCLUSIONS

In rats, AP was associated with impaired cardiodynamics, disturbed cardiac OS, antioxidant defence and cardiac pathologic changes in hypertensive conditions. Hypertension was associated with an increase in the AP radiographic area. Further studies should confirm whether root canal treatment can have a cardioprotective effect and reduce cardiac OS in hypertensive conditions.

PRIASE 2021 guidelines for reporting animal studies in Endodontology: explanation and elaboration

Laws and ethics require that before conducting human clinical trials, a new material, device or drug may have to undergo testing in animals in order to minimize health risks to humans, unless suitable supporting grandfather data already exist. The Preferred Reporting Items for Animal Studies in Endodontology (PRIASE) 2021 guidelines were developed exclusively for the specialty of Endodontology by integrating and adapting the ARRIVE (Animals in Research: Reporting In Vivo Experiments) guidelines and the Clinical and Laboratory Images in Publications (CLIP) principles using a validated consensus-based methodology. Implementation of the PRIASE 2021 guidelines will reduce potential sources of bias and thus improve the quality, accuracy, reproducibility, completeness and transparency of reports describing animal studies in Endodontology. The PRIASE 2021 guidelines consist of a checklist with 11 domains and 43 individual items and a flowchart. The aim of the current document is to provide an explanation for each item in the PRIASE 2021 checklist and flowchart and is supplemented with examples from the literature in order for readers to understand their significance and to provide usage guidance. A link to the PRIASE 2021 explanation and elaboration document and PRIASE 2021 checklist and flowchart is available on the Preferred Reporting Items for study Designs in Endodontology (PRIDE) website (http://pride-endodonticguidelines.org/priase/).

Cardio-protective and Anti-atherosclerosis Effect of Crocetin on Vitamin D3 and HFD-induced Atherosclerosis in Rats

Cardiovascular disease (CVD) is a chronic disease and causes the highest rate of death globally. CVD-related deaths account for 80% of all deaths in low and middle-income countries, such as China. Crocetin (CT), a carotenoid phytoconstituent already confirm their anti-inflammatory and antioxidant effects in various diseases animal models. In the study, we make effort to access the cardio-protective effect of Crocetin against vitamin D3 and high fat induced atherosclerosis in rats and scrutinize the underlying mechanism. Sprague Dawley (SD) rats were used in this study and rats were divided into different groups and high fat diet and vitamin D was used for induction the atherosclerosis. The rats were received oral administration of crocetin (5, 10 and 15 mg/kg) and simvastatin (0.5 mg/kg) until 30 days. At the end of the experimental period, lipid, cardiac markers, anti-inflammatory, antioxidant, pro-inflammatory cytokines and atherogenic index were estimated. The mRNA expression of Intercellular adhesion molecule-1 (ICAM-1), Monocyte Chemoattractant Protein-1 (MCP-1) and vascular cell adhesion molecule 1 (VCAM-1) in aortic tissue of the atherosclerotic rats. Crocetin significantly reduced the aortic membrane thickness and platelet aggregation rates. Crocetin also dose-dependently reduced total cholesterol (TC), very low-density lipoprotein (VLDL), triacylglycerol (TG), low-density lipoprotein (LDL) and augmented the level of high-density lipoprotein (HDL) level. Additionally, Crocetin significantly (p < 0.001) abridged the level of malonaldehyde (MDA) and augmented the level of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione peroxidase (GPx). Furthermore, Crocetin significantly (p < 0.001) dose-dependently reduced the levels of pro-inflammatory cytokines and inflammatory mediators. Crocetin attenuated mRNA expression of VCAM-1, ICAM-1 and MCP-1. Crocetin had anti-atherosclerosis and cardio-protective effects on vitamin D3 and high fat induced atherosclerosis in rats through anti-inflammatory and antioxidant mechanisms.

Influence of a High-fat Diet in the Progression of Apical Periodontitis

INTRODUCTION

This study evaluated the effects of a high-fat diet (HFD) on the progression of apical periodontitis (AP) in rats.

METHODS

Eight-week old Wistar rats (N = 24) were included in this study. Half of the animals received an HFD and the other half a control diet (CD). AP lesions were induced 8 weeks later by creating pulp exposure of the mandibular left first molars. The animal's body mass was verified on a weekly basis. After 21 and 40 days, the animals were sacrificed. Blood was collected for biochemical tests, and the liver was removed for hepatic triglycerides analysis. The left hemimandibles were removed, radiographed, and then prepared for histologic evaluation. The right hemimandibles (region near molars) were removed for bone mineral density analysis by dual-energy X-ray absorptiometry.

RESULTS

Radiographs showed that AP lesions were significantly larger in the HFD group compared with the CD group (P < .05). Histologic analysis confirmed that the AP lesions were larger and revealed a more severe inflammatory infiltrate in the HFD group. Bone mineral density was reduced in the HFD group compared with the CD groups (P < .05). The HFD resulted in a significant increase in body mass (P < .05), liver mass (P < .05), relative liver mass (P < .05), and hepatic triglycerides (P < .05). The levels of triglycerides and very-low-density lipoprotein were significantly higher in the 40-day HFD group compared with the 21-day HFD and 21- and 40-day CD groups (P < .05).

CONCLUSIONS

Findings suggest that an HFD can influence the progression and severity of AP.

Relationship between Apical Periodontitis and Metabolic Syndrome and Cardiovascular Events: A Cross-Sectional Study

Aim: Both apical periodontitis (AP) and metabolic syndrome (MetS) are associated with atherosclerotic cardiovascular disease (ACVD), the main cause of cardiovascular events. The aim of this study was to investigate the prevalence of AP and the oral inflammatory burden in control subjects and patients suffering cardiovascular events, analyzing the possible association between AP and the oral inflammatory burden with MetS. Materials and Methods: Using a cross-sectional design, 83 patients suffering a cardiovascular event were recruited in the study group (SG), and 48 patients without cardiovascular events were included in the control group (CG). Periapical index (PAI) was used to diagnose AP, and total dental index (TDI) was used to assess the total oral inflammatory burden. Diagnosis of MetS was made by meeting three or more American Heart Association Scientific Statement components. Results: In the multivariate logistic regression analysis, the number of teeth with AP (OR = 2.3; 95% C.I. = 1.3–4.3; p = 0.006) and TDI scores (OR = 1.5; 95% C.I. = 1.2–1.9; p = 0.001), significantly correlated with cardiovascular events. MetS was strongly associated (OR = 18.0; 95% C.I. = 6.5–49.7; p = 0000) with cardiovascular events. Higher TDI scores were significantly associated with MetS (OR = 1.3; 95% C.I. = 1.1–1.6; p = 0.003. Neither the number of root-filled teeth (RFT) (OR = 0.9; 95% C.I. = 0.6–1.3; p = 0.61) nor the number of teeth with apical periodontitis (OR = 1.1; 95% C.I. = 0.8–1.7; p = 0.49) were associated with MetS. Conclusions: Apical periodontitis is significantly associated with cardiovascular events. Total oral inflammatory burden assessed by TDI, but not AP alone, is associated with MetS.