Temperature-driven carboxylic acid production from waste activated sludge and food waste: Co-fermentation performance and microbial dynamics.

This work aims to improve the continuous co-fermentation of waste activated sludge (WAS) and food waste (FW) by investigating the long-term impact of temperature on fermentation performance and the underpinning microbial community. Acidogenic co-fermentation of WAS and FW (70:30 % VS-basis) to produce volatile fatty acids (VFA) was studied in continuous fermenters at different temperatures (25, 35, 45, 55 °C) at an organic loading rate of 11 gVS/(L·d) and a hydraulic retention time of 3.5 days. Two batches of WAS (A and B) were collected from the same wastewater treatment plant at different periods to understand the impact of the WAS microbioota on the fermenters' microbial communities. Solubilisation yield was higher at 45 °C (575 ± 68 mgCOD/gVS) followed by 55 °C (508 ± 45 mgCOD/gVS). Fermentation yield was higher at 55 °C (425 ± 28 mgCOD/gVS) followed by 35 °C (327 ± 17 mgCOD/gVS). Temperature also had a noticeable impact on the VFA profile. At 55 °C, acetic (40 %) and butyric (40 %) acid dominated, while acetic (37 %), butyric acid (31 %), and propionic acid (17 %) dominated at 35 °C. At 45 °C, an accumulation of caproic acid was detected which did not occur at other temperatures. Each temperature had a distinct microbial community, where the WAS microbiota played an important role. The biomass mass-balance showed the highest growth of microorganisms (51 %) at 35 °C and WAS_B, where a consumption of acetic acid was observed. Therefore, at 35 °C, there is a higher risk of acetic acid consumption probably due to the proliferation of methanogens imported from WAS.

Endodontic variables in patients with SARS-CoV-2 infection (COVID-19) in relation to the severity of the disease.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is the cause of the ongoing coronavirus disease 2019 (COVID-19) pandemic. It has been hypothesized oral health may be related to the severity and complications of COVID-19. The aim of this study was to analyze the prevalence of apical periodontitis and the frequency of root canal treatment in a sample of patients with SARS-CoV-2 infection (COVID-19), correlating them with the severity of the disease. MATERIAL AND METHODS: This retrospective study was conducted following the Strengthening Reporting Observational Studies in Epidemiology (STROBE) guidelines. The study examined 280 patients with positive real time PCR COVID-19 test whose treatment was performed in our hospital. Fifty-two patients aged 52.3 ± 17.3 years, including 30 males and 22 females, who had an orthopantomography in their clinical record, performed in the last 2 years, were included. Patients with SARS-CoV-2 infection were grouped as mild or moderate (MM) and severe or critical (SC) illness groups, according to the NIH COVID-19 Treatment Guidelines (Wu & McGoogan 2020). Radiographic records were analyzed and apical periodontitis (AP) was diagnosed as radiolucent periapical lesions (RPLs), using the periapical index score (PAI). Student's t test, χ2 test and multivariate logistic regression were used in the statistical analysis. RESULTS: The number of carious teeth was significantly higher in the SC group (3.4 ± 4.1), which showed more than twice as many teeth with carious lesions than the MM group (1.4 ± 1.8) (p = 0.02). Multivariate regression analysis showed association between the number of carious teeth and the severity of SARS-CoV-2 disease (OR = 1.5; 95% CI = 1.1-2.1; p = 0.017). Endodontic status (OR = 7.12; 95% CI = 1.2-40.9; p = 0.027) also correlated with the disease severity. CONCLUSIONS: The results suggest that the oral health status of COVID-19 patients correlated with the severity of the SARS-CoV-2 virus infection. Significant association has been found between the severity of COVID-19 disease and the presence of a greater number of teeth with caries lesions, as well as with endodontic status.

Inflammatory profile of apical periodontitis associated with liver fibrosis in rats: histological and immunohistochemical analysis.

AIM: To investigate the effects of liver fibrosis (LF) on the pro-inflammatory mediators and periapical bone resorption of apical periodontitis (AP) in rats. METHODOLOGY: Forty male Wistar rats were distributed into four groups: C - control, AP - rats with AP, LF - rats with LF, AP + LF - rats with AP and LF. LF was induced by carbon tetrachloride administration for 8 weeks and surgical bile duct ligation for 4 weeks; AP was induced in the teeth of rats by dental pulp exposure to the oral environment for 30 days. Jaws and livers were removed after euthanasia. Haematoxylin and Eosin (H&E) and Picrosirius Red (PSR) staining were used to confirm fibrosis in the livers. The jaws were analysed using H&E staining, immunohistochemical assays of interleukin (IL)-1ß, IL-6 and tumour necrosis factor-alpha (TNF-α). Student's t-test and Mann-Whitney's U-test were used for statistical analysis (P < 0.05). RESULTS: Inflammatory infiltrate was moderate in the AP group and severe in the AP + LF group (P < 0.05). Periapical bone resorption was significantly larger in the AP + LF group compared with the AP group (P < 0.05). IL-1ß, IL-6 and TNF-α levels were significantly higher in AP + LF group when compared to the AP group (P < 0.05). CONCLUSION: More intense inflammatory infiltrate, greater amounts of pro-inflammatory cytokines and increased periapical bone resorption were observed in the presence of liver fibrosis in rats with exposed pulps.

Prevalence of endodontic infection in patients with Crohn´s disease and ulcerative colitis.

BACKGROUND: Previous studies have linked apical periodontitis (AP) to inflammatory bowel disease (IBD). The aim of this study was to compare the prevalence of AP and root canal treatment (RCT) in patients with ulcerative colitis (UC) and Crohn´s disease (CD). MATERIAL AND METHODS: A cross-sectional study, including 28 patients with Crohn´s disease and 26 with ulcerative colitis, was conducted. AP was diagnosed as radiolucent periapical lesions (RPLs), using the periapical index score (PAI). Student's t test, 2 test and multivariate logistic regression were used in the statistical analysis. RESULTS: Multivariate logistic regression run with age, gender, number of teeth, number of RFT, periodontal disease and the type of IBD as covariates, taking as dependent variable and outcome "periapical status" (0 = no tooth with RPL; 1 = at least one tooth with RPL), showed that both UC and CD patients had the prevalence apical periodontitis (OR = 1.03; C.I. 95% = 0.25 - 4.31; p = 0.97). The multivariate analysis, including all the above covariates, shows that both in UC and CD patients the prevalence of RCT was similar (OR = 0.76; C.I. 95% = 0.17 - 7.31; p = 0.73). Periapical status was significantly associated with endodontic status (OR = 42.72; C.I. 95% = 3.87 - 472.15; p = 0.002), regardless of IBD type. CONCLUSIONS: The results of the present study show similar frequency of AP and RFT in both UC and CD patients. The type of IBD does not appear to affect the prevalence of radiographically detectable periapical lesions or the prevalence of root canal treatment.

Evaluation of undergraduate Endodontic teaching in dental schools within Spain.

AIM: To evaluate the current situation of undergraduate endodontic teaching in Spanish dental schools. METHODOLOGY: An online version, translated into Spanish, of a survey conducted in the UK (Int Endod J 52, 2019, 1077) was sent via email to the undergraduate endodontic programme leads in all 23 Spanish dental schools. RESULTS: The response rate was 96%. In 95% of dental schools, endodontics is taught in the fourth year. Students treat simple root canal treatment cases in 100% of schools and only in 40% treat moderate cases. In 65% of schools, students are supervised by full-time professors who are specialists in Endodontics, significantly more frequently in private dental schools (P = 0.002). Spanish dental schools use both rotary and reciprocating instrumentation systems during endodontic training, with consistency on methods of working length determination, use of silicate-based endodontic cements, irrigating solutions, inter-visit medicaments and canal filling techniques. No type of magnification is used in 90% of dental schools, and only 25% use ultrasonic instruments. Private dental schools have a significantly better staff: student ratio during clinical practice (P = 0.041), spend significantly more hours in clinical training (P = 0.04) and have significantly greater number of clinical areas specifically dedicated to Endodontics (P = 0.010). CONCLUSIONS: Undergraduate endodontic teaching in Spanish dental schools follows the key recommendations of the ESE Undergraduate Curriculum Guidelines (Int Endod J 46, 2013, 1105), being, in most respects, comparable to that carried out in the UK (Int Endod J 52, 2019, 1077). The use of magnification and ultrasonic instruments needs to be increased. Private schools reported better results than public schools in some of the variables that were analysed.

A simple novel approach for detecting blood-brain barrier permeability using GPCR internalization.

AIMS: Impairment of blood-brain barrier (BBB) is involved in numerous neurological diseases from developmental to aging stages. Reliable imaging of increased BBB permeability is therefore crucial for basic research and preclinical studies. Today, the analysis of extravasation of exogenous dyes is the principal method to study BBB leakage. However, these procedures are challenging to apply in pups and embryos and may appear difficult to interpret. Here we introduce a novel approach based on agonist-induced internalization of a neuronal G protein-coupled receptor widely distributed in the mammalian brain, the somatostatin receptor type 2 (SST2). METHODS: The clinically approved SST2 agonist octreotide (1 kDa), when injected intraperitoneally does not cross an intact BBB. At sites of BBB permeability, however, OCT extravasates and induces SST2 internalization from the neuronal membrane into perinuclear compartments. This allows an unambiguous localization of increased BBB permeability by classical immunohistochemical procedures using specific antibodies against the receptor. RESULTS: We first validated our approach in sensory circumventricular organs which display permissive vascular permeability. Through SST2 internalization, we next monitored BBB opening induced by magnetic resonance imaging-guided focused ultrasound in murine cerebral cortex. Finally, we proved that after intraperitoneal agonist injection in pregnant mice, SST2 receptor internalization permits analysis of BBB integrity in embryos during brain development. CONCLUSIONS: This approach provides an alternative and simple manner to assess BBB dysfunction and development in different physiological and pathological conditions.

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

AIM: To investigate the relationship between apical periodontitis and atherosclerosis in rats by lipid profile and carotid artery intima tunic measurement, and histological and histometric evaluation of periapical lesions. METHODOLOGY: Forty male Wistar rats were allocated into four groups: control (C), with apical periodontitis (AP), with atherosclerosis (AT) and with AP and AT (AP + AT). Atherosclerosis was induced using a high-lipid diet associated with a surgical ligature in the carotid artery and a super dosage of vitamin D3 . AP was induced via pulp exposure to the oral environment. At 45 and 75 days, serum levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured. The maxillary and mandibular jaws and carotid artery were collected and processed for histological analysis. The Kruskal-Wallis or Mann-Whitney test was performed for nonparametric data, and the Tukey's or Student's t-test was performed for parametric data (P < 0.05). RESULTS: In nonatherosclerotic animals, the induction of apical periodontitis increased TG levels significantly, from 63.1 ± 11.4 mg dL-1 in group C to 88.2 ± 7.9 mg dL-1 in the AP group (P < 0.05). The induction of AP was associated with a trend for higher TC and LDL-C levels in atherosclerotic animals (P > 0.05); however, it only significantly increased TG levels, from 93.2 ± 18.0 mg dL-1 in AT group to 121.9 ± 14.5 mg dL-1 in the AP + AT group (P < 0.05). Animals in the AP + AT group had a 36.5% increase in the thickness of the carotid intima tunic when compared with the AT group (P < 0.05). The intensity of the inflammatory infiltrate was significantly larger in the AP + AT group when compared with AP group (P < 0.05). The AP + AT group exhibited significantly greater alveolar bone loss, with a periapical lesion size of 206.4 ± 56.3 × 104 µm2 , compared with 151.4 ± 49.1 × 104 µm2 in the AP group (P < 0.05). CONCLUSION: Apical periodontitis influenced triglyceride levels, increasing them even in the absence of atherosclerosis, and influenced the increase in the thickness of the carotid artery intima tunic in the presence of atherosclerosis. Atherosclerosis intensified the inflammatory reaction and increased bone resorption in periapical lesions.

Cardiovascular diseases and apical periodontitis: association not always implies causality.

BACKGROUND: Several studies published in the last two decades have found an association between the prevalence of apical periodontitis (AP) or root canal treatment (RCT) and cardiovascular diseases (CVDs). However, the demonstration of association does not prove by itself the existence of a cause-effect relationship. Two diseases can appear as statistically related without any of them directly affecting the values of the other, resulting in a non-causal relationship. The aim of this narrative review is to summarize the current state of knowledge regarding the association between AP and CVDs, analysing it according to the Hill's causality criteria. MATERIALS AND METHODS: Epidemiological studies carried out on the association between CVDs and AP or RCT published in English until 8 December 2019 were identified. Forty-four articles were selected and its results were analysed. RESULTS: Numerous cross-sectional epidemiological studies have found significant relationship between CVDs and AP. The odds ratio values range 1.6 - 5.4. However, other studies have not found significant association. Respect to RCT, some studies found correlation, but others found no association or even found that RCT is a protective factor against CVDs. CONCLUSIONS: The results are inconsistent and a causal relationship between CVDS and endodontic disease cannot be stablished. The risk factors common to both diseases can act as confounding factors, biasing the results. To reach definitive conclusions about the type of association (causal or non-causal) between both diseases, longitudinal epidemiological studies must be carried out to establish the temporal relationship and the dose-response gradient.

Association between dental anxiety and intraoperative pain during root canal treatment: a cross-sectional study.

AIM: To investigate whether dental anxiety influences the intraoperative pain felt by patients during root canal treatment. METHODOLOGY: In a cross-sectional design, 180 patients (90 men and 90 women) were included. Pre-operative anxiety levels were assessed using the short-form Dental Anxiety Inventory (S-DAI). Pain during root canal treatment was evaluated using a 10-cm visual analogue scale (VAS) that ranked the level of pain between 'Absence of pain' and 'Unbearable pain'. The minimal sample size was determined using the software of the National Center for Advancing Translational Sciences (NIH, UK). Multivariate logistic regression analysis was used to identify relationships between variables. RESULTS: Mean pain level during root canal treatment was 2.2 ± 2.1. The mean anxiety S-DAI score was 27.2 ± 12.5. Fifty percent of men had mild anxiety levels, while in 70% of women anxiety was moderate or high (P = 0.017). Anxiety correlated positively with intraoperative pain (R = 0.406). Multivariate logistic regression analysis revealed that anxiety was significantly associated with intraoperative pain felt by patients (OR = 4.0; 95% C.I. = 1.7-9.3; P = 0.001). CONCLUSIONS: Anxious patients were more than twice as likely to feel moderate or intense intraoperative pain during root canal treatment. To know the patient´s degree of anxiety could help the dentist to decide whether to use anxiolytic premedication and/or supplemental local anaesthesia to assure better control of pain during root canal treatment.

Association between diabetes and the outcome of root canal treatment in adults: an umbrella review.

BACKGROUND: Diabetes mellitus is the most common metabolic disorder amongst dental patients. The association between the diabetes and the outcome of root canal treatment is unclear. AIM: To conduct an umbrella review to determine whether there is an association between diabetes and the outcome of root canal treatment. DATA SOURCE: The protocol of the review was developed and registered in the PROSPERO database (CRD42019141684). Four electronic databases (PubMed, EBSCHOhost, Cochrane and Scopus databases) were used to perform a literature search until July 2019. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: Systematic reviews with or without meta-analyses published in English assessing any outcomes of root canal treatment comparing diabetic and nondiabetic patients were included. Two reviewers were involved independently in study selection, data extraction and appraising the reviews that were included. Disagreements were resolved with the help of a third reviewer. STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of the reviews was assessed using the AMSTAR tool (A measurement tool to assess systematic reviews), with 11 items. Each AMSTAR item was given a score of 1 if the criterion was met, or 0 if the criterion was not met or the information was unclear. RESULTS: Four systematic reviews were included. The AMSTAR score for the reviews ranged from 5 to 7, out of a maximum score of 11, and all the systematic reviews were classified as 'medium' quality. LIMITATIONS: Only two systematic reviews included a meta-analysis. Only systematic reviews published in English were included. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS: Diabetes mellitus is associated with the outcome of root canal treatment and can be considered as a preoperative prognostic factor.

Endodontics and diabetes: association versus causation.

Endodontic Medicine has gained more attention and is becoming a more important issue in Endodontics. As an example, more than one hundred articles on this topic have been published in the last eight years. Several of these studies have found an association between endodontic variables, that is the prevalence of apical periodontitis, the prevalence of root canal treatment (RCT) and the outcome of RCT assessed as root filled teeth (RFT) with radiolucent periapical lesions (RPL) or non-retained RFT, and several systemic diseases, such as diabetes, cardiovascular disease, smoking habits, osteoporosis, inherited coagulopaties, biological medications, low birth weight or physical fitness. However, the demonstration of association does not prove by itself the existence of a cause-effect relationship. Two variables can be related statistically to each other without either variable directly affecting the values of the other thus resulting in a non-causal relationship. Causality is assumed when one variable is shown to contribute to the development of the other, and its removal is shown to reduce the frequency of disease. Therefore, once a significant statistical association has been found between two variables, it is necessary to exclude the presence of bias, which would imply that the association is artefactual, and to analyse if the causation criteria defined by Hill (Proceedings of the Royal Society of Medicine 1965; 58: 295-300) are fulfilled to establish a causal relationship. Only if they are satisfied, can it be concluded that the association is causal. The aim of this study was to analyse the difference between association and causation, applying the criteria of causality to the specific case of the association between endodontic disease and diabetes mellitus.

Association between diabetes and nonretention of root filled teeth: a systematic review and meta-analysis.

Previous studies have found an association between the outcome of root canal treatment (RCT) and diabetic status. This systematic review and meta-analysis aimed to analyse the potential relationship between diabetes and the occurrence of extracted root filled teeth (RFT). The clinical PICO question was as follows: in adult patients with RFT, does the absence or presence of diabetes influence the prevalence of RFT extraction? The key words used in the systematic search were as follows: (Diabetes OR Diabetes Mellitus OR Hyperglycaemia OR Diabetic) AND (Endodontic OR Endodontics OR Endodontic Treatment OR Root Canal Treatment OR Root Canal Preparation OR Root Canal Therapy OR Root Filled Teeth OR Endodontically Treated Teeth) AND (Extraction OR Retention OR Survival OR Success OR Failure OR Outcome). The primary outcome variable was odds ratio (OR) for the frequency of extracted RFT in diabetics and healthy subjects. The method of DerSimonian-Laird with random effects was used to calculate the overall OR. Three hundred titles were identified, and three studies achieved the inclusion criteria. Data from 54 936 root canal treatments, 50 301 in nondiabetic control subjects and 4635 in diabetic patients, were analysed. The calculated overall odds ratio (OR = 2.44; 95% CI = 1.54-3.88; P = 0.0001) implies that diabetics had a significantly higher prevalence of extracted RFT than healthy nondiabetic subjects. The results of available studies indicate a significant relationship between DM and increased frequency of nonretained root filled teeth. Diabetes mellitus should be considered an important preoperative prognostic factor in root canal treatment.

Chemical risks associated with ready-to-eat vegetables: quantitative analysis to estimate formation and/or accumulation of disinfection byproducts during washing.

Fresh produce can become contaminated with disease-causing microorganisms and chemical contaminants at every step of the production and processing chain and in a variety of ways, including through contact with contaminated process water. Water quality is critical to prevent microbial and chemical risks in any of the postharvest and processing operations related to fresh and fresh-cut fruits and vegetables. The wash process requires high volumes of water, which are usually reduced by water reuse. To maintain the microbiological quality of the process water, intervention strategies are needed. Chemical disinfection is the most common method to maintain the microbial quality of process water. However, the use of chemicals leads to the formation/accumulation of disinfection byproducts (DBPs), which can be absorbed by the washed vegetables. This is the case of trihalomethanes (THMs) and chlorates. The presence of high concentrations of DBPs in vegetables has led to an intensive debate on current disinfection practices and how DBPs may enter the food supply chain, becoming a potential health risk for consumers. To assess the risk associated with the formation/accumulation of DBPs in process water, a quantitative analysis was done. Available data have been used to develop mathematical models to predict the formation/accumulation of DBPs (chlorates and THMs) in process water due to the use of chlorine-derived compounds. Preliminary models have been developed, but adjustments are still needed to refine them. The present study contributes more information related to the development of a mathematical model for the accumulation of chlorates and THMs in process water.

Effectiveness and clinical implications of the use of topical antibiotics in regenerative endodontic procedures: a review.

Regenerative endodontic procedures (REPs) are biologically based procedures planned to replace damaged tissues, including dentinee and root structures, as well as cells of the pulp-dentine complex. Effective sterilization of the root canal is essential in REPs, and antibiotics have been widely used to disinfect root canals. The aim of this paper was to review the scientific literature on (i) Effectiveness of antibiotics used in REPs against bacteria implicated in endodontic disease; (ii) Scientific evidence supporting the use of topical antibiotics in REPs; (iii) Clinical implications of the use of antibiotics in REPs and the possible side effects; (iv) Effect of antibiotics on dental pulp stem cells; and (v) Ongoing research on the use of antibiotics in REPs. Antibiotics used in REPs are effective against bacteria implicated in endodontic infections. Triple antibiotic pastes with minocycline attain complete disinfection of immature teeth with necrotic pulps, without affecting SCAP. Experimental studies carried out in dogs support the use of antibiotics in REPs. Clinical studies report high success rates of RET using antibiotics as intracanal dressings. However, tooth discolouration is an important side effect of the use of TAP. An antibiotic paste containing only metronidazole and ciprofloxacin could be a good alternative to the use of TAP. The use of antibiotic-containing scaffolds or clindamycin-modified triple antibiotic (metronidazole, ciprofloxacin and clindamycin) polymer could be a biologically safe antimicrobial drug delivery system in REPs.

Four Years' Experience in the Diagnosis of Very Long-Chain Acyl-CoA Dehydrogenase Deficiency in Infants Detected in Three Spanish Newborn Screening Centers.

Identification of very long-chain acyl-CoA dehydrogenase deficiency is possible in the expanded newborn screening (NBS) due to the increase in tetradecenoylcarnitine (C14:1) and in the C14:1/C2, C14:1/C16, C14:1/C12:1 ratios detected in dried blood spots. Nevertheless, different confirmatory tests must be performed to confirm the final diagnosis. We have revised the NBS results and the results of the confirmatory tests (plasma acylcarnitine profiles, molecular findings, and lymphocytes VLCAD activity) for 36 cases detected in three Spanish NBS centers during 4 years, correlating these with the clinical outcome and treatment. Our aim was to distinguish unambiguously true cases from disease carriers in order to obtain useful diagnostic information for clinicians that can be applied in the follow-up of neonates identified by NBS.Increases in C14:1 and of the different ratios, the presence of two pathogenic mutations, and deficient enzyme activity in lymphocytes (<12% of the intra-assay control) identified 12 true-positive cases. These cases were given nutritional therapy and all of them are asymptomatic, except one. Seventeen individuals were considered disease carriers based on the mild increase in plasma C14:1, in conjunction with the presence of only one mutation and/or intermediate residual activity (18-57%). In addition, seven cases were classified as false positives, with normal biochemical parameters and no mutations in the exonic region of ACADVL. All these carriers and the false positive cases remained asymptomatic. The combined evaluation of the acylcarnitine profiles, genetic results, and residual enzyme activities have proven useful to definitively classify individuals with suspected VLCAD deficiency into true-positive cases and carriers, and to decide which cases need treatment.

European Society of Endodontology position statement: the use of antibiotics in endodontics.

This position statement represents a consensus of an expert committee convened by the European Society of Endodontology (ESE) on Antibiotics in Endodontics. The statement is based on current scientific evidence as well as the expertise of the committee. The goal is to provide dentists and other healthcare workers with evidence-based criteria for when to use antibiotics in the treatment of endodontic infections, traumatic injuries of the teeth, revascularization procedures in immature teeth with pulp necrosis, and in prophylaxis for medically compromised patients. It also highlights the role that dentists and others can play in preventing the overuse of antibiotics. A recent review article provides the basis for this position statement and more detailed background information (International Endodontic Journal, 2017, https://doi.org/10.1111/iej.12741). Given the dynamic nature of research in this area, this position statement will be updated at appropriate intervals.

Dental students' knowledge regarding the indications for antibiotics in the management of endodontic infections.

AIM: To determine the knowledge of undergraduate Spanish dental students regarding the indications of systemic antibiotics in the management of endodontic infections. METHODOLOGY: The final year dental students from four Spanish dental schools were requested to answer a one-page questionnaire on the indications for systemic antibiotics in the treatment of endodontic infections. One hundred and seventy-five students were asked to participate in this research. Data were analysed using descriptive statistics and chi-square test. RESULTS: One hundred and four students (93.7%) completed satisfactorily the survey and were included in the study. The average duration of antibiotic therapy was 7.0 ± 2.0 days. All respondents chose amoxicillin as the first-choice antibiotic in patients with no medical allergies, alone (47%) or associated with clavulanic acid (53%). The first drug of choice for patients with an allergy to penicillin was clindamycin 300 mg (99%). For cases of irreversible pulpitis, up to 63% of students would prescribe antibiotics. For the scenario of a necrotic pulp, symptomatic apical periodontitis and no swelling, 44% would prescribe antibiotics. Almost 40% of students would prescribe antibiotics for necrotic pulps with asymptomatic apical periodontitis and a sinus tract. CONCLUSIONS: It is necessary for the Spanish schools of dentistry to improve students' knowledge about antibiotics and their indications in endodontics. Interactive education analysing real endodontic cases using problem-based learning would help students acquire better skills in prescribing antibiotics in pulp-periapical pathosis.