Periapical Bone Research Articles

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

To evaluate the influence of the early life stress (ELS) on the severity of the apical periodontitis (AP) in Wistar rats. 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 3h 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). 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). Early life stress is predictive of the severity of AP exacerbating the inflammatory process and increasing periapical bone resorption.

Selenium ameliorates inflammation by decreasing autophagic flux and mitogen-activated protein kinase signalling on experimentally induced rat periapical lesions.

To reveal the molecular mechanisms that targets mitogen-activated protein kinase (MAPK) signalling and the autophagic flux and to investigate the possible effects of the systemic administration of selenium (Se) on experimentally induced rat periapical lesions. Thirty adult Sprague-Dawley rats were divided equally into negative control, positive control and Se groups. In the positive control and Se groups, the pulp chambers of their mandibular first molars were exposed to the oral environment to induce periapical lesions The Se group received daily intraperitoneal injections of Se at a dose of 0.1mg kg-1 . After 28 days, the amount of bone destruction; severity of inflammation; penetration of microorganisms along the root canal; collagen degradation in periodontal ligament; interleukin (IL)-6, hypoxia-inducible factor-1 (HIF-1), cyclooxygenase-2 (COX-2) and caspase-3 expression; autophagic flux; and p38 MAPK signalling were evaluated using radiographic, histopathological, Gram staining, picrosirius red stain, immunohistochemical, quantitative real-time polymerase chain (qRT-PCR) and Western blot methods, respectively. These data were analysed through the Kruskal-Wallis and Dunnett's tests (p < .05). The area of radiographic periapical bone loss, histopathological scores, the area of periapical bone loss and the scores for the bacteria localisation, the intensity of immunohistochemical staining for IL-6, HIF-1, COX-2 and caspase-3 in the Se group was significantly less than those of the positive control group (p < .01). The mRNA expression levels of Beclin-1, Atg3, Atg5, Atg7 and Atg16L1 were lower in the Se group than in the positive control group (p < .01). The protein expressions of Beclin-1, Atg5 and LC3-II, the phosphorylation ratio of the p38 MAPK and the ratios of LC3II/LC3I were significantly higher (p < .05) in the positive control and Se groups. On the contrary, the expression of the p62/SQSTM1 protein was significantly lower (p < .05) in the positive control and Se groups than in the negative control group. The induction of periapical lesions in rats increased autophagic flux and activated p38 MAPK signal transduction processes. Se suppressed the inflammatory process, reduced bone destruction and both the autophagic flux and p38 MAPK activation.

The Changes in Size of Periapical Lesions after Root Canal Treatments Assessed by Digital Periapical Radiography and Cone-Beam Computed Tomography: A 2-Years Prospective Clinical Study.

Background and Objectives: There is limited information regarding comparison of long-term dynamics of periapical bone destruction estimated by digital periapical radiography (DPR) and by cone-beam computed tomography (CBCT). This study aimed to compare the radiographically assessed periapical changes of endodontically treated teeth over 2 years of follow-up and to analyse disagreements in periapical lesion size estimates around the same roots using DPR and CBCT. Materials and Methods: A total of 176 endodontically treated teeth, of 128 patients with apical periodontitis, were assessed by DPR and CBCT, at baseline and after 2 years. All periapical radiolucencies were categorised by severity (S0, S1, S2, S3) concerning their size. Descriptive statistics were used to report distribution of the radiolucencies at baseline and at follow-up, and their size transitions over 2 years. Site-specific comparison of the radiolucencies identified by two methods was performed using Z test and Pearson’s chi-square test. Results: majority of the detected radiolucencies were scored as S0: 65% and 68% at baseline; 89% and 83% at follow-up, by DPR and CBCT, respectively. Site-specific score comparison showed that disagreements comprised 18% and 20% of the total number of radiolucencies detected by DPR and CBCT, respectively. There were more disagreements between DPR and CBCT within categories S1 and S2 + S3 compared to S0: at baseline, they comprised 17–33% and after two years 62–95% of all detected radiolucencies within the category. 65% of non-matching score transitions over two years occurred between S0 and S1. The CBCT-based evaluation resulted in negative treatment outcomes for 10 more root canals than the DPR-based result. Conclusions: Most remarkable disagreement between DPR and CBCT recordings was observed within the radiolucency categories S2 and S3. However, the diagnostic accuracy of both radiographic methods was questionable as it resulted in a high proportion of non-matching S0-S1 lesion transitions over 2 years.

Iatrogenic Extrusion of Calcium Silicate Cements on Teeth Associated with Large Periapical Lesion: A Case Report with 12-Month Follow-up

Traumatic dental injuries can result in pulp necrosis and apical periodontitis, impairing root development. When this condition is left untreated, it causes inflammation in the tissues at the apex, which may lead to significant damage of the periapical alveolar bone. Tooth with open apex may have a risk of iatrogenic error of extrusion material during the stage of root canal obturation. Objective: This case report discussed the bone healing of large periapical lesion of an iatrogenic extrusion of calcium silicate cement in an open apex maxillary left central incisor. Case report: A 35-year-old female patient presented with a main complaint of a discoloured upper front tooth that was affecting with her appearance. Clinical examination showed her left maxillary central incisor was diagnosed with pulp necrosis and symptomatic apical periodontitis. Periapical radiograph revealed the tooth has an open apex and large periapical lesion. After chemomechanical disinfection, an apical plug was placed with bioceramic material. Periapical radiographs taken postoperatively demonstrated the extrusion of bioceramic material into the periapical lesion. After a year, the tooth does not exhibit any symptoms, and periapical radiographs showed that the periapical region has totally healed. Conclusion: Extruded bioceramic material has no detrimental impact on periapical tissue healing, as evidenced by 12-month follow-up observations.

Revisiting the role of IL-1 signaling in the development of apical periodontitis.

Apical periodontitis (AP) develops as a result of an immune response to pulpal bacterial infection, and various cytokines are involved in the pathogenesis of AP, with Interleukin (IL)-1 being considered a key cytokine. The role of IL-1 in the pathogenesis of AP has been well studied. It is known that IL-1 expression in periapical lesions correlates closely with the development of AP. IL-1 is a potent bone-resorptive cytokine that induces osteoclast formation and activation. Hence, inhibiting its signaling with IL-1 receptor antagonist (IL-1RA) results in a reduction in periapical lesion size. On the other hand, IL-1 is also a central cytokine that combats bacterial infection by activating innate immune responses. Therefore, a complete loss of IL-1 signaling leads to a failure to limit bacterial dissemination and consequently exacerbates AP. In vivo, IL-1 expression is tightly regulated and its signaling is modulated to optimize the immune response. Obesity causes systemic low-grade chronic inflammation and increases the risk of cardiovascular, renal, and other disorders. In experimentally induced AP, obesity significantly increases periapical bone loss, albeit the underlying mechanism remains unclear. Recent technological innovations have enabled more comprehensive and detailed analyses than previously, leading to new insights into the role of IL-1RA in regulating IL-1 signaling, and modulating apical lesion progression in obesity. In this review, we provide a brief overview of the function of IL-1 in AP development, with special emphasis on the latest findings in normal weight and obese states.

3D printed scaffold for repairing bone defects in apical periodontitis

ObjectivesTo investigate the feasibility of the 3D printed scaffold for periapical bone defects.MethodsIn this study, antimicrobial peptide KSL-W-loaded PLGA sustainable-release microspheres (KSL-W@PLGA) were firstly prepared followed by assessing the drug release behavior and bacteriostatic ability against Enterococcus faecalis and Porphyromonas gingivalis. After that, we demonstrated that KSL-W@PLGA/collagen (COL)/silk fibroin (SF)/nano-hydroxyapatite (nHA) (COL/SF/nHA) scaffold via 3D-printing technique exhibited significantly good biocompatibility and osteoconductive property. The scaffold was characterized as to pore size, porosity, water absorption expansion rate and mechanical properties. Moreover, MC3T3-E1 cells were seeded into sterile scaffold materials and investigated by CCK-8, SEM and HE staining. In the animal experiment section, we constructed bone defect models of the mandible and evaluated its effect on bone formation. The Japanese white rabbits were killed at 1 and 2 months after surgery, the cone beam computerized tomography (CBCT) and micro-CT scanning, as well as HE and Masson staining analysis were performed on the samples of the operation area, respectively. Data analysis was done using ANOVA and LSD tests. (α = 0.05).ResultsWe observed that the KSL-W@PLGA sustainable-release microspheres prepared in the experiment were uniform in morphology and could gradually release the antimicrobial peptide (KSL-W), which had a long-term antibacterial effect for at least up to 10 days. HE staining and SEM showed that the scaffold had good biocompatibility, which was conducive to the adhesion and proliferation of MC3T3-E1 cells. The porosity and water absorption of the scaffold were (81.96 ± 1.83)% and (458.29 ± 29.79)%, respectively. Histological and radiographic studies showed that the bone healing efficacy of the scaffold was satisfactory.ConclusionsThe KSL-W@PLGA/COL/SF/nHA scaffold possessed good biocompatibility and bone repairing ability, and had potential applications in repairing infected bone defects.Clinical significance The 3D printed scaffold not only has an antibacterial effect, but can also promote bone tissue formation, which provides an alternative therapy option in apical periodontitis.

Buccal plate thickness as a predictor for endodontic microsurgery outcomes: A retrospective cohort study

The aim of the study was to determine the relationship between preoperative buccal plate thickness (BPT) and radiographic healing at the osteotomy site after endodontic microsurgery (EMS) with and without guided tissue regeneration (GTR) using cone beam computed tomography (CBCT) imaging. The retrospective sample of 143 individuals who had EMS with pre- and postoperative CBCT scans availablewere divided into 2 groups: group 1 (GTR) and group 2 (no GTR), which were further divided into teeth where BPT was >1.0 mm or ≤1.0 mm. Bone healing was assessed by subjective evaluation of bone formation attheresected root surface (I1), periapical bone formation (I2), cortical plate formation (I3), and a derived index (Author2-Author1 Indices) (I4), calculated by a composite score of I1 and I2. There was no significant impact on surgical healing with the use of GTR when BPT is >1.0 mm. The GTR had a significant impact on surgical healing when the BPT was ≤1.0 mm. This study supported the use of CBCT to evaluate three-dimensional healing after EMS. The Author2-Author1 index was found to be a clinically relevant method for assessing healing. To improve healing rate, the EMS cases with a preoperative BPT of ≤1.0 mm may benefit from GTR.

Impact of systemic health on treatment outcomes in endodontics.

The healing of periapical lesions after root canal treatment (RCT) is not the result of the curative action of the treatment. The process of healing begins with inflammation, and is resolved by the clearance of the immunogen that induces the immune response. Then, the periapical tissue itself carries out the healing of the periapical lesion, by repair or by a combination of repair and regeneration, depending on the host's reparative response working properly. The ultimate objective of RCT is to achieve wound healing by removing the source of bacterial antigens and toxins, allowing chronic inflammatory tissue to become reparative tissue. Some systemic conditions increase the susceptibility of the host to infection or impair the tissue reparative response, maintaining the inflammatory process and periapical bone resorption after RCT. This can cause the failure of RCT and even the need for extraction of the affected tooth. To analyse the scientific literature on the possible influence of systemic conditions on the treatment outcomes in endodontics, as well as to discuss the biological mechanisms that may be involved. The search was carried out in PubMed, SCOPUS and EMBASE. The inclusion criteria established were original scientific articles reporting data about some systemic condition in relation to treatment outcomes in endodontics, including clinical studies and studies carried out in animal models. Systemic factors (age, nutrition, stress, hormones, smoking habits), and systemic diseases, such as diabetes, cardiovascular diseases, osteoporosis, HIV infection, inflammatory bowel disease, and others, can influence or interfere in the repair of periapical tissues after RCT. Some of these systemic diseases can alter bone turnover and fibroblast function, preventing or delaying periapical wound healing. Others can alter the microvasculature, reducing nutrients and oxygen supply to periapical tissues. As a result, these systemic conditions can decrease the success rate of RCT and provoke incomplete wound healing (typically granulomatous tissue formation) in the periapical region. The results of this narrative review show worse success rate of RCT, with higher percentage of postoperative radiolucent periapical lesions and higher proportion of non-retained teeth (RFT), associated with several systemic conditions, such as smoking habits and diabetes.

Radiographic predictors for MRONJ in oncologic patients undergoing tooth extraction

Tooth extraction is a risk factor for the development of osteonecrosis of the jaw following treatment with antiresorptive drugs (ARDs), but not all extraction sites develop this pathology. Therefore, we aimed to identify local radiographic predictors of Medication-Related Osteonecrosis of the Jaw (MRONJ) in panoramic images of oncologic patients undergoing tooth extraction. Based on a retrospective longitudinal cohort study design, patients were included if undergoing one or more tooth extraction, with at least one administration of ARDs, and presence of pre- and post-operative panoramic radiographs. After data collection, blinded and independent observations were performed. Eleven distinct imaging-related parameters were assessed preoperatively and five postoperatively, at each extraction site. A case–control and subgroup analysis assessing MRONJ development was performed. Significance level is set to 0.05 (5%). A total of 77 oncologic patients were selected, undergoing 218 tooth extractions, from which 63 teeth (29%) in 39 patients (51%) developed MRONJ. Results showed that patients developed significantly more MRONJ with longer ARD treatment (p = 0.057), teeth with absent and incomplete endodontic fillings with caries, widened periodontal ligament space and/or periapical lesions (p = 0.005), and sclerotic and heterogenous bone patterns (p = 0.005). In conclusion, tooth extraction sites presenting with infections and bone sclerosis are at higher risk to develop MRONJ.

Effectiveness of revitalization in treating apical periodontitis: A systematic review and meta-analysis.

Revitalization procedures primarily aim to eliminate clinical symptoms and heal periapical lesions. The objective of the study was to elucidate the effectiveness of revitalization in treating apical periodontitis in necrotic mature and immature permanent teeth based on the following PICO question: In patients with permanent immature or mature teeth and pulp necrosis with or without signs of apical periodontitis (P) what is the effectiveness of revitalization (I) in comparison with calcium hydroxide apexification, apical plug and root canal treatment (C) in terms of tooth survival, pain, tenderness, swelling, need for medication (analgesics and antibiotics), radiographic evidence of reduction of apical lesion size, radiographic evidence of normal periodontal ligament space, radiographic evidence of increased root thickness and length (not for mature teeth), tooth function (fracture and restoration longevity), need for further intervention, adverse effects (including exacerbation, restoration integrity, allergy and discolouration), oral health-related quality of life (OHRQoL), presence of sinus tract and response to sensibility testing (O). (T)=Defined as a minimum of 1year and maximum of as long as possible for all outcome measures, except 'pain, tenderness, swelling, need for medication (analgesics)', which is a minimum of 7 days and maximum of 3months and OHRQoL which is minimum of 6months and a maximum of as long as possible. Three databases (PubMed, Embase and Cochrane Library) were searched for human, experimental and observational studies in English, complemented with hand search, until 31/10/2021. Studies recruiting teeth with pulp necrosis (with/without apical periodontitis), with minimum 10 teeth/arm at the end of the study and with a follow-up of at least 1year, were included. Records without an abstract and a full text were excluded. The qualitative analysis of the included (non-) randomized controlled clinical trials was performed with the Revised Cochrane risk-of-bias tools (RoB 2 and ROBINS-I). Meta-analysis for survival and success (including a subgroup analysis for mature/immature permanent teeth) was performed using the Mantel-Haenszel method. The certainty of evidence was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation). From the 365 identified records, five met the inclusion criteria. The 12 months survival rate was 100% for all (im)mature permanent teeth in all groups (3 studies). The success rate at 12 months was 100% for immature permanent teeth for I and C (1 study), however, reduced to 92% and 80% for mature teeth in I and C respectively (1 study, p > .05). The risk of bias for the most critical outcome (survival) was high for two studies and low for one. For the critical outcome success, all assessed studies were highly biased. Meta-analyses provided pooled relative risk with no statistically significant difference between I and C for both survival (RR=1.00, 95%CI=0.96-1.04, p=1.00) and success (RR=1.06; 95%CI=0.83-1.35, p=.66). The evidence level for survival was kept 'low' and for success was downgraded to 'very low' due to inconsistency and imprecision. The survival and success rates were favourable in all included studies and for all groups; however, these outcomes are not reliable due to the low certainty level. Clinically, the most reported adverse event was tooth discolouration, hence the application of bismuth oxide containing calcium silicate cements should be avoided in revitalization. Radiographically, caution is needed when assessing periapical bone healing and further root development with periapical radiographs, due to multifactorial inaccuracies of this imaging technique. Methodological and assessment concerns need to be addressed in future clinical trials. Long-term results are necessary for studies reporting revitalization of mature permanent teeth, as they seem to be experimental so far. No robust evidence was discovered to support that revitalization is effective to treat apical periodontitis in (im)mature permanent teeth. The success and survival rates of revitalized and fully pulpectomized (im)mature permanent teeth did not differ significantly. Prospero: CRD42021262466.

Effect of an Extremely Low-Frequency Electromagnetic Field on the Concentration of Salivary Immunoglobulin A.

Extremely Low-Frequency Electromagnetic Field (ELF MF) therapy is effective in the treatment of injury, inflammation and postoperative complications. Its clinical applications relate to bone unification, pain reduction, soft tissue oedema and the decrease of electric potentials in the oral cavity. It enhances regeneration of periapical bone lesions. It is obvious that cells (leukocytes, platelets, keratinocytes, osteoblasts) and proteins (fibrin, collagen, elastin and growth factors) exhibit alterations when exposed to an Extremely Low-Frequency Electromagnetic Field. The aim of the study was to evaluate the effect of an Extremely Low-Frequency Electromagnetic Field (ELF MF) on the parotid gland on the concentration of salivary immunoglobulin A. The study group consisted of 24 patients, aged 14–16, who underwent ELF MF on the parotid gland region. The control group comprised 25 matching persons. The IgA concentration in saliva samples was established using radial immunodiffusion. Following ELF MF, a statistically significant increase in the concentration of secretory immunoglobulin A was found in the study group, whereas in the control group, no statistically significant differences were noted. It can be concluded that an Extremely Low-Frequency Electromagnetic Field increases the activity of the immune system of the parotid gland.

Chronic systemic corticosteroid therapy influences the development of pulp necrosis and experimental apical periodontitis, exacerbating the inflammatory process and bone resorption in rats.

The main aim of the study was to evaluate the inflammatory response and development of apical periodontitis in rats chronically treated with glucocorticoids. Male Wistar rats (Rattus novergicus) were randomly divided into two groups: the experimental group, which was treated with prednisone (5mg/kg/day) and a control group, which was administered saline solution for 30days before induction of apical periodontitis, continuing until the day of euthanasia days 0, 7, 14 and 28 after injury induction. The mandibles were subjected to histological evaluation to determine the size of the lesion, was also performed for the presence and absence of pulp necrosis, bone resorption and micro abscesses, and histomorphometric analyses were performed based on the number of polymorphonuclear cells and mononuclear cells. Histochemical analysis was also performed to assess the percentage of collagen fibres and their typification, in addition to immunohistochemistry for the inflammatory markers interleukin IL-1β, IL-6, TNF-α and TRAP. Despite after 7days, there was no differences between groups, a significant increase in the root pulp necrosis (p=.001), micro-abscesses (p=.026) and the size of the apical lesion on the 14th day of treatment with prednisone (p=.008). On the same day, there was also an increase in the number of polymorphonuclear cells (p=.042) and cells immunostained for IL-1β (p=.006), IL-6 (p<.001) and TRAP (p=.002) in animals treated with prednisone. The numbers of mononuclear cells also increase in 28days (p=.025) and TNF-α ± increases in the prednisone group on the 7th day (p=.041). The prednisone group also showed a decrease in collagen after 14 (both type I [p=.041] and type III [p=.046]) and 28 type III (p=.002) days after the coronary opening. The glucocorticoids modified the development of experimental apical periodontitis induced in rats, causing an early increase in periapical bone resorption and pulp necrosis. These effects are associated with alterations in cytokine levels, in the inflammatory response and in collagen deposition, in the 14th day after injury induction.

Vertical root fracture diagnosis in endodontically treated teeth

Annotation. Timely diagnosis of vertical root fractures is a big challenge to dentists, because there are no specific clinical signs, symptoms and X-ray features. The aim of the research is to study clinical cases of vertical root fractures in endodontically treated teeth and to carry out analysis the methods of their diagnosis, clinical features and radiological characteristics. In patients aged 40-65 years, 34 clinical cases of vertical root fracture are considered. The main and additional methods of patients’ examination are analyzed. The statistical calculation of the obtained results is performed by the method of variation statistics with the determination of the Student’s t-test using computer programs Microsoft® Excel 2017 and “Statistica 6.1”. Clinical symptoms and abnormal findings during examination were recorded but not subjected to statistical analysis. Clinical examination revealed periodontal swelling or abscess in 6 patients, isolated narrow and deep periodontal pocket in 24 patients, low localized fistula in 9 patients. Radiological results: only in 6 clinical cases a vertical fracture line was observed on intraoral X-ray images; in 30 cases the destruction of bone tissue in the periapical area, mainly in the halo-type radiolucency was determined; in 4 cases no pathological changes in periapical bone tissue were revealed. Vertical root fracture was confirmed by muco-periosteal flap detachment in all cases. It has been established that a number of signs, namely: isolated deep narrow periodontal pocket; coronally located fistula; characteristic bone destruction (J-shaped or “halo” radiolucency) on the radiograph indicate the likelihood of vertical root fracture. Signs of fenestration of the bone adjacent to the fractured root and visualization of the fracture line after mucoperiosteal flap surgery are pathognomonic.

Correlation between Transforming Growth Factor-β and Periapical Lesions in Patients with Chronic Apical Periodontitis.

Objective To examine the expression of transforming growth factor-β (TGF-β) in the periapical granulation tissue and serum of patients with chronic apical periodontitis and to conduct immunohistochemical analysis so as to explore the relationship between TGF-β and the degree of periapical lesions. Methods Periapical granulation tissues of 20 cases of chronic apical periodontitis were collected as the experimental group. Healthy gingival tissues without eruption of third molars of 5 cases were collected as the control group. Immunohistochemistry, enzyme-linked immunosorbent assay, and real-time PCR (RT-PCR) were utilized to determine the expression of TGF-β mRNA and protein, and the difference in the expression of TGF-β was compared between groups. In the experimental group, oral CBCT was taken to measure the periapical bone resorption area. Spearman's correlation method was applied to analyze the correlation between TGF-β protein and gene expression levels and periapical bone resorption area. Results Immunohistochemistry and enzyme-linked immunosorbent assay demonstrated that the expression of TGF-β protein in chronic apical periodontitis tissue and serum was higher than that in the controls (P < 0.05). RT-PCR revealed that the expression of TGF-β mRNA was higher in chronic apical periodontitis tissue than that of the controls (P < 0.05). Spearman's correlation analysis showed that in the experimental group, the mRNA expression of TGF-β was positively correlated with the periapical bone resorption area (P < 0.01), and the protein expression level was not correlated with the periapical bone resorption area (P < 0.05). Conclusion The increased expression of TGF-β in the periapical granulation tissue and serum of patients with chronic apical periodontitis has a certain correlation with the progression of periapical periodontitis. The correlation between TGF-β at the mRNA level and the degree of early stage disease as well as the high expression of TGF-β in inflammatory cells in immunohistochemistry have confirmed that TGF-β promotes bone resorption in early periapical periodontitis, and its mechanism of action deserves further investigation.

Indigenous microbiota protects development of medication-related osteonecrosis induced by periapical disease in mice

Bacterial infection is a common finding in patients, who develop medication-related osteonecrosis of the jaw (MRONJ) by the long-term and/or high-dose use of anti-resorptive agents such as bisphosphonate (BPs). However, pathological role of bacteria in MRONJ development at the early stage remains controversial. Here, we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model. C57/BL6 female mice were treated with intragastric broad-spectrum antibiotics for 1 week. Zoledronic acid (ZOL) through intravenous injection and antibiotics in drinking water were administered for throughout the experiment. Pulp was exposed on the left maxillary first molar, then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to heal. All mice were harvested, and cecum, maxilla, and femurs were collected. ONJ development was assessed using μCT and histologic analyses. When antibiotic was treated in mice, these mice had no weight changes, but developed significantly enlarged ceca compared to the control group (CTL mice). Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics, which was confirmed by decreased osteoclasts and inflammation. ZOL treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone amount. Furthermore, antibiotics treatment could further exacerbate bone necrosis, with increased osteoclast number. Our findings suggest that the commensal microbiome may play protective role, rather than pathological role, in the early stages of MRONJ development.

Dental Pulp Regeneration Induced by Allogenic Mesenchymal Stromal Cell Transplantation in a Mature Tooth: A Case Report

IntroductionCellular therapy constitutes a new therapeutic alternative in regenerative endodontics. In this case report, we evaluated the capacity of allogeneic mesenchymal stromal cells (MSCs) to induce dental pulp and apical bone regeneration in a tooth previously endodontically treated. MethodsA healthy 55-year-old female patient consulting for swelling and a sinus tract associated with tooth #8 was referred for an endodontic evaluation. Previously, tooth #8 had undergone root canal treatment and apical resection and had no response to thermal or electric pulp testing. Radiographically, tooth #8 showed root canal treatment, a cut apex angle, and periapical radiolucency. The root canal was recleaned and shaped, and calcium hydroxide was used as an interappointment medication. Cryopreserved allogeneic bone marrow MSCs were thawed, expanded, incorporated into preclotted platelet-rich plasma, and implanted into the pulp cavity of tooth #8. The cervical part of the canal was sealed with bioceramic cement and a composite. ResultsAfter 14 months of MSC transplantation, tooth #8 showed sensitivity to cold and electric pulp tests. Radiographic and cone-beam computed tomographic imaging showed signs of increased periapical bone density, healing of the periapical lesion, and almost complete apical remodeling. ConclusionsThis case report shows periodontal bone formation, apex remodeling, and dental pulp regeneration induced by allogeneic MSC transplantation in a mature nonvital tooth. Allogeneic MSCs may constitute a first-line therapy in regenerative endodontics.

Effects of Anti–Receptor Activator of Nuclear Factor Kappa B Ligand Antibody and Zoledronic Acid on Periapical Lesion Development in Mice

IntroductionAntiresorptive drugs are widely used to treat osteoporosis and other systemic bone diseases, although their efficacy for local bone resorption after localized inflammation has not been fully elucidated. We examined the effects of an anti–receptor activator of nuclear factor kappa B ligand (RANKL) antibody and the bisphosphonate zoledronic acid (ZOL) on periapical lesion (PL) development in mice. MethodsDental pulp of lower first molars in mice was removed, with the exposed dental pulp chambers left open to the oral environment to induce apical periodontitis. An anti-RANKL antibody or ZOL was intraperitoneally injected once per week until postoperative day 21, and then micro–computed tomographic imaging and histologic analyses were performed. ResultsPL enlargement was inhibited by both the anti-RANKL antibody and ZOL in a dose-dependent manner, and a reduction of inflammatory cell infiltration in apical tissues inhibited periapical bone resorption. The anti-RANKL antibody decreased the number of osteoclasts in periapical tissues, whereas ZOL suppressed periapical bone resorption with osteoclast numbers maintained. Although the administration of each of the antiresorptive drugs increased femoral bone mass, femoral bone mineral density in the PL group was lower compared with the sham-operated group. ConclusionsThese results suggest that an antiresorptive drug administered systemically is distributed to areas of local inflammation in the jaw can prevent PL development.

Assessment of periapical reactive bone after the endodontic treatment by using fractal dimension analysis

Assessment of periapical reactive bone after the endodontic treatment by using fractal dimension analysis

Macrophage M1 polarization mediated via the IL-6/STAT3 pathway contributes to apical periodontitis induced by Porphyromonas gingivalis.

To investigate the involvement of IL-6/STAT3 signaling pathway activation in macrophage polarization and bone destruction related to apical periodontitis (AP) stimulated by Porphyromonas gingivalis. Macrophage polarization, IL-6/STAT3 expression, and the presence of P. gingivalis were detected in human AP tissues via RT-qPCR, western blotting, and immunohistochemistry staining. Murine bone marrow derived macrophages were isolated and cultured with P. gingivalis W83 in vitro, and levels of macrophage IL-6 expression, STAT3 phosphorylation, and macrophage polarization with or without the selective STAT3 phosphorylation inhibitor Stattic (5 μM) were detected via ELISA, western blotting, RT-qPCR, and flow cytometry, respectively. P. gingivalis-induced murine AP models were constructed, and bone destruction and macrophage polarization in the apical region were evaluated. Transwell co-culture systems were used to investigate the effects of macrophages infected with P. gingivalis on osteogenesis and osteoclastogenesis. P. gingivalis was detected in human AP tissues that highly expressed IL-6/STAT3, and the M1 subtype of macrophages was more abundant in these tissues. P. gingivalis infection induced IL-6 expression, STAT3 phosphorylation, and M1 polarization of macrophages, while 5 μM of Stattic partially abolished these activation effects. Systemic STAT3 blockade via oral administration of Stattic at a dose of 25 mg kg-1 alleviated murine periapical bone resorption and apical infiltration of M1 macrophages induced by P. gingivalis infection in vivo. Furthermore, macrophages infected with P. gingivalis promoted bone destruction via secretion of IL-6, TNF-α, and RANKL, which hinder pre-osteoblast expression of Runx2 and accelerate pre-osteoclast expression of NFAT2. The activation of IL-6/STAT3 signaling pathway is involved in mediating macrophages M1 polarization in the P. gingivalis induced apical inflammatory context and may also be intimately involved in the bone loss caused by P. gingivalis infection, directing the M1 macrophage infiltration during the progression of AP.

Efficacy of Oregano Essential Oil Extract in the Inhibition of Bacterial Lipopolysaccharide (LPS)-Induced Osteoclastogenesis Using RAW 264.7 Murine Macrophage Cell Line—An In-Vitro Study

Gram-negative, anaerobic bacterias are predominate in periapical infections. The bacterial lipopolysaccharide (LPS) initiates the process of inflammation and periapical bone resorption. Usage of various medicaments retards or inactivates the bacterial endotoxin (LPS). However, the results are not highly effective. In recent years, owing to antimicrobial resistance, the shift from conventional agents to herbal agents has been increased tremendously in research. Keeping this in mind, the present study was formulated to evaluate the efficacy of oregano essential oil in inhibiting bacterial LPS- induced osteoclastogenesis. Four different concentrations (0 ng/mL, 25 ng/mL, 50 ng/mL, and 100 ng/mL) of oregano essential oil extract were added into 96-well culture plate. Under light microscope, quantification of osteoclast cells was performed. One-way ANOVA with post-hoc Tukey test was carried out on SPSS v21. A significant reduction (p &lt; 0.001) in the osteoclast was observed in the experimental groups compared to no oregano essential oil extract (control). A dose-dependent significant reduction (p &lt; 0.001) in osteoclast formation was observed among the experimental groups, with lesser osteoclast seen in group IV with 100 ng/mL of oregano essential oil extract. Thus, it can be concluded that oregano essential oil extract can be utilized as a therapeutic agent that can target bacterial LPS-induced osteoclastogenesis. However, randomized controlled studies should be conducted to assess the potential use of this extract in the periapical bone resorption of endodontic origin.