Effects of microplastics on the kidneys: a narrative review.

Microplastics (MPs) and nanoplastics are small synthetic organic polymer particles (<5 mm and <1 µm, respectively) that originate directly from plastic compounds or result from the degradation of plastic. These particles are a global concern because they are widely distributed in water, air, food, and soil, and recent scientific evidence has linked MPs to negative biological effects. Although these particles are difficult to detect in humans, MPs have been identified in different biological fluids and tissues, such as the placenta, lung, intestines, liver, blood, urine, and kidneys. Human exposure to MPs can occur by ingestion, inhalation, or dermal contact, potentially causing metabolic alterations. Data from experimental and clinical studies have revealed that the ability of MPs to promote inflammation, oxidative stress, and organ dysfunction and negatively affect clinical outcomes is associated with their accumulation in body fluids and tissues. Although evidence of the putative action of MPs in the human kidney is still scarce, there is growing interest in studying MPs in this organ. In addition, chronic kidney disease requires investigation because this condition is potentially prone to MP accumulation. The purpose of the present article is (i) to review the general aspects of MP generation, available analytic methods for identification, and the main known biological toxic effects; and (ii) to describe and critically analyze key experimental and clinical studies that support a role of MPs in kidney disease.

Leaching and cytotoxicity of bismuth oxide in ProRoot MTA - A laboratory investigation.

AIM: The present study examined the leaching and cytotoxicity of bismuth from ProRoot MTA and aimed to identify whether bismuth leaching was affected by the cement base and the immersion regime used. METHODOLOGY: The leaching profile of bismuth was examined from ProRoot MTA and compared with hydroxyapatite containing 20% bismuth oxide as well as hydroxyapatite and tricalcium silicate to investigate whether bismuth release changed depending on the cement base. Bismuth leaching was determined after 30 and 180 days of ageing immersed in Dulbecco's modified Eagle's medium (DMEM) using mass spectroscopy (ICP-MS). The media were either unchanged or regularly replenished. The pH, surface microstructure and phase changes of aged materials were assessed. Wistar rat femoral bone marrow stromal cells (BMSCs) and cutaneous fibroblasts were isolated, cultured and seeded for cell counting (trypan blue live/dead) after exposure to non-aged, 30- and 180-days-aged samples in regularly replenished DMEM. Aged DMEM in contact with materials was also used to culture BMSCs to investigate the effect of material leachates on the cells. Gene expression analysis was also carried out after direct exposure of cells to non-aged materials. Differences between groups were statistically tested at a significance level of 5%. RESULTS: All materials exhibited alterations after immersion in DMEM and this increased with longer exposure times. The bismuth leached from ProRoot MTA as detected by ICP-MS. Aged ProRoot MTA samples exhibited a black discolouration and surface calcium carbonate deposition. ProRoot MTA influenced cell counts after direct exposure and its 180-days leachates reduced BMSC viability. After direct BMSC contact with non-aged ProRoot MTA an upregulation of metallothionein (MT1 and MT2A) expression and down-regulation of collagen-1a (Col-1a) and bone sialoprotein (BSP) expression was identified. CONCLUSIONS: Bismuth leaching was observed throughout 180-days observation period from all materials containing bismuth oxide. This negatively influenced cell viability and gene expression associated with bismuth exposure. This is the first study to report that metallothionein gene expression was influenced by exposure to ProRoot MTA.

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

OBJECTIVES: To evaluate the biocompatibility, physical and chemical properties of three pre-mixed calcium silicate-based sealers and an epoxy resin-based material were assessed. Pre-mixed sealers supposedly obtain water from the root canal moist to hydrate and set. MATERIALS AND METHODS: Polyethylene tubes were filled with the materials Bio-C Sealer Ion+, Bio-C Sealer, EndoSequence BC Sealer and AH Plus Jet, or left empty and surgically implanted in the subcutaneous tissue of Wistar rats. The animals were euthanised and the tubes and tissue were removed for histological analysis and scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS). Materials' surface chemical characterisation was assessed using Raman spectroscopy and SEM/EDS. Flow, setting time (in two conditions), solubility, radiopacity and pH were also analysed. ANOVA and Bonferroni correction were performed for comparisons (P < 0.05). RESULTS: Inflammatory response observed in the tissues subsided from 7 to 30 days. Tungsten migration could be detected in the surrounding tissue following AH Plus Jet implantation. All calcium silicate-based sealers exhibited zirconium oxide (radiopacifier) and tricalcium silicate peaks before and after implantation. All materials exhibited flow values above 17 mm. An approximately tenfold difference was observed between the plaster- and metal-mould setting times of the calcium silicate cements indicating its sensitivity to moist variations and solubility above 8% was also observed for these materials. CONCLUSIONS: Pre-mixed materials exhibited variable setting time and solubility with a decreasing inflammatory response. CLINICAL RELEVANCE: The variable moist-dependant setting time with high solubility poses a concern for the clinical use of these pre-mixed sealers.

Microbiological profile of root canals indicated for endodontic retreatment due to secondary endodontic infections or for prosthetic reasons.

OBJECTIVE: The objective of this study was to evaluate the microbiological profile of root canals indicated for endodontic retreatment due to secondary endodontic infections evidenced by the presence of chronic apical periodontitis (G1) or for prosthetic reasons, without clinical and radiographic signs of endodontic reinfection (G2). METHODS: Microbiological samples were collected from thirty teeth (N=30) out of which 15 were indicated for retreatment due to the presence of chronic apical periodontitis (G1) and 15 were indicated exclusively for prosthetic reasons (G2). Samples were collected from root canals before (S1), after chemomechanical preparation (S2), and after 30 days of intracanal medication composed of calcium hydroxide and 2% chlorhexidine gel (S3). The molecular analysis was performed using Nested-PCR for the detection of 17 bacterial species. The efficacy of each stage of the retreatment in reducing the microbial load was verified by counting colony-forming units (CFU). The statistical analysis considered a significance level of 5%. RESULTS: The results showed that bacteria were detected in 100% of the cases in S1, in both groups, by Nested PCR. The most frequently found species in S1 in both groups were Enterococcus faecalis, Fusobacterium nucleatum, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Parvimonas micra. The microbial load of G1 was higher than G2 in the initial samples (S1). Endodontic retreatment was effective in reducing the microbial load in G1 and G2. Statistically significant associations were found between specific bacteria and clinical signs and symptoms. CONCLUSION: It was concluded that the microbial community present in the root canal of teeth indicated for endodontic retreatment is mixed and heterogeneous. G1 and G2 differ in the number of species per case and microbial load. CLINICAL RELEVANCE: Endodontic retreatment was effective in reducing the microbial load. Statistically significant associations were found between specific bacteria and clinical signs and symptoms.

In vitro physicochemical characterization of five root canal sealers and their influence on an ex vivo oral multi-species biofilm community.

AIM: To evaluate the physicochemical properties of five root canal sealers and assess their effect on an ex vivo dental plaque-derived polymicrobial community. METHODOLOGY: Dental plaque-derived microbial communities were exposed to the sealers (AH Plus [AHP], GuttaFlow Bioseal [GFB], Endoseal MTA [ESM], Bio-C sealer [BCS] and BioRoot RCS [BRR]) for 3, 6 and 18 h. The sealers' effect on the biofilm biomass and metabolic activity was quantified using crystal violet (CV) staining and MTT assay, respectively. Biofilm community composition and morphology were assessed by denaturing gradient gel electrophoresis (DGGE), 16S rRNA sequencing and scanning electron microscopy. The ISO6876:2012 specifications were followed to determine the setting time, radiopacity, flowability and solubility. Obturated acrylic teeth were used to assess the sealers' effect on pH. Surface chemical characterization was performed using SEM with coupled energy-dispersive spectroscopy. Data normality was assessed using the Shapiro-Wilk test. One-way anova and Tukey's tests were used to analyze data from setting time, radiopacity, flowability and solubility. Two-way anova and Dunnett's tests were used for the data analysis from CV, MTT and pH. 16S rRNA sequencing data were analyzed for alpha (Shannon index and Chao analysis) and beta diversity (Bray-Curtis dissimilarities). Differences in community composition were evaluated by analysis of similarity (p < .05). RESULTS: The sealers significantly influenced microbial community composition and morphology. All sealers complied with ISO6876:2012 requirements for setting time, radiopacity and flowability. Although only AHP effectively reduced the biofilm biomass, all sealers, except BRR, reduced biofilm metabolic activity. CONCLUSION: Despite adequate physical properties, none of the sealers tested prevented biofilm growth. Significant changes in community composition were observed. If observed in vivo, these changes could affect intracanal microbial survival, pathogenicity and treatment outcomes.

Comparative analysis of bacterial content, levels of lipopolysaccharides and lipoteichoic acid in symptomatic and asymptomatic endodontic infections at different stages of endodontic treatment.

OBJECTIVES: This study aimed to detect the presence of specific bacteria and to evaluate the levels of lipopolysaccharides (LPS) and lipoteichoic acid (LTA) in symptomatic necrotic root canals associated with acute apical abscess (symptomatic group - GI). It also aimed to compare the findings with those presented by asymptomatic necrotic root canals (asymptomatic group - GII) in the different stages of the endodontic treatment. MATERIALS AND METHODS: Microbiological samples were collected from 20 root canals, including purulent collection from acute apical abscesses, before and after chemo-mechanical preparation (CMP) preparation (CMP) with chlorhexidine gel 2% and after 30 days of intracanal medication (ICM) with (Ca[OH]2) + chlorhexidine. The culture method was used to evaluate the efficacy of CMP and ICM. Nested PCR was used to detect the presence of 17 specific bacteria. Levels of LPS were measured by using limulus amebocyte lysate, whereas enzyme-linked immunosorbent assay was used for the quantification of LTA. RESULTS: CMP was effective in reducing the microbial load in both groups (P < 0.05). LPS levels were higher in GI than in GII (P < 0.05). There was a significant reduction in the LPS levels after CMP and ICM (P < 0.05) in GI and GII. LTA levels were significantly reduced in GI after ICM and in GII after CMP and ICM (both P < 0.05). Fusobacterium nucleatum and Enterococcus faecalis were frequently identified in both groups, alone or in combination with each other. CONCLUSION: Different species were detected in all stages of the endodontic treatment. CMP was able to reduce bacterial content and the levels of LPS, but not of LTA in the symptomatic group. High levels of LPS were correlated with spontaneous pain and pain to percussion in the symptomatic group. CLINICAL RELEVANCE: This clinical study showed that chemo-mechanical preparation was able to reduce bacterial load and levels of LPS, but not of LTA in the symptomatic group. Elevated levels of LPS were correlated with the presence of symptomatology.

The association of inadequate lip coverage and malocclusion with dental trauma in Brazilian children and adolescents - A systematic review and meta-analysis.

BACKGROUND/AIM: Dental trauma (DT) occurs frequently in children and adolescents. Therefore, understanding the factors associated with its occurrence in these age groups is important to establish specific preventive measures. The aim of this study was to investigate the relationships of lip coverage, overjet, and open bite to dental trauma in Brazilian children and adolescents. MATERIAL AND METHODS: The review protocol was registered in the PROSPERO database (CRD42020156290) and the bibliographic search was performed in nine electronic databases until July 2020. The studies included were observational, performed in Brazil, with healthy children and adolescents (0-19 years old), and without the restriction of date or language. Two reviewers assessed the individual risk of bias of the eligible studies with a standardized checklist. The meta-analyses were stratified by dentition stage and age range using fixed or random effects, odds ratio (OR) as the effect measure, and 95% confidence interval. The heterogeneity across studies was assessed with the I² test and the GRADE approach assessed the certainty of evidence. RESULTS: The search presented 2493 initial results, from which 55 met the eligibility criteria and were included. Most studies (67%) presented a low risk of bias and were published between 2000 and 2019. Children and adolescents with inadequate lip coverage are 1.86-2.36 times more likely to suffer from DT, while those with increased overjet are 1.94-3.11 times more likely. Children with primary dentitions and anterior open bites are 1.76 (95% CI: 1.20-2.59) times more likely to suffer from DT. The certainty of evidence varied from very low to moderate. CONCLUSIONS: Inadequate lip coverage, increased overjet, and anterior open bite are associated with the occurrence of dental trauma in Brazilian children and adolescents.

Physicochemical, antimicrobial, and biological properties of White-MTAFlow.

OBJECTIVES: To evaluate a new material containing tantalum oxide as an alternative radiopacifier, and a water-based gel for hydration, in comparison with two calcium silicate-based cement: ProRoot MTA and Biodentine. MATERIALS AND METHODS: ProRoot MTA (Dentsply), Biodentine (Septodont), and a new hydraulic calcium silicate cement White-MTAFlow (Ultradent) (in 'thin' consistency) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The interaction with dentin was also assessed using SEM and EDS. Physical and chemical properties radiopacity, setting time, linear flow, volumetric central filling, and lateral flow, pH, and volume change were investigated together with the color luminosity (L) and color change (ΔE). The agar diffusion and direct contact antimicrobial activity, and methylthiazolyldiphenyl-tetrazolium-bromide (MTT) cytotoxicity using human fibroblast cells were also evaluated. Data were statistically analyzed at a 5% significance level. RESULTS: All materials were composed of tricalcium and dicalcium silicate but had different radiopacifiers, and calcium hydroxide (portlandite) deposition was detected in XRD analysis. White-MTAFlow exhibited radiopacity values in accordance with ISO standard, and the longest setting time. The water-based gel provided the highest linear flow, a comparable cavity central filling, and the highest groove-lateral flow in the volumetric flow analysis. White-MTAFlow exhibited an alkalinity reduction, and Biodentine, a progressive increase of pH values after 28 days. However, similar volume loss for White-MTAFlow was assessed in comparison to Biodentine after the 28-day immersion. White-MTAFlow showed the highest L value (91.5), and ProRoot MTA the lowest (78.1) due to dentin staining caused by bismuth migration. None of the materials exhibited inhibition halos against the tested bacteria, and similar turbidity values were obtained after 48 h in direct contact with E. faecalis, indicating an upregulation to bacterial growth. White-MTAFlow showed MTT cytocompatibility similarly to the control group. CONCLUSIONS: White-MTAFlow in 'thin' consistency presents comparable physicochemical, biological, and antimicrobial properties to ProRoot MTA and Biodentine, and does not cause color alteration in dentin. CLINICAL RELEVANCE: White-MTAFlow is a suitable material for use as reparative endodontic cement. Further studies considering its biocompatibility are necessary.

Evaluation of the presence of microorganisms from root canal of teeth submitted to retreatment due to prosthetic reasons and without evidence of apical periodontitis.

AIM: The objective of this study was to evaluate the presence of microorganisms in the root canals (RC) of teeth submitted to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis. MATERIAL AND METHODS: Twenty teeth referred to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis were included in this study. Gutta-percha (GP) was collected from each third of the RC. After GP removal, microbial samples were also collected from the full extension of RC using paper points and files. The samples were cultivated in Fastidious Anaerobe Agar and the colony-forming units (CFU/mL) were counted. They were also semi-quantitatively analyzed by checkerboard DNA-DNA hybridization using 40 DNA bacterial probes. RESULTS: Microorganisms were found in all samples. The coronal third of GP was more contaminated than the apical third (p ≤ 0.05). There was prevalence of Enterococcus hirae and Enterococcus faecalis in all RC thirds and also in the samples collected from the full extension of RCs. CONCLUSION: Microorganisms were found in all cases referred to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis. Enterococcus was the genus most frequently detected. CLINICAL SIGNIFICANCE: An endodontic retreatment should be considered before replacing a prosthesis.

Physical, chemical, and biological properties of white MTA with additions of AlF3.

OBJECTIVES: Addition of aluminum fluoride (AlF3) to MTA was tested to inhibit dental discoloration. MATERIALS AND METHODS: MTA Angelus with 0, 5, 15, and 45% AlF3 were tested. The set cements were characterized using scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. Radiopacity and setting time were analyzed according to ANSI/ADA 57 and ASTM C266-08. Volume change was evaluated using volumetric micro-CT analysis. The pH and calcium ion release were assessed after 3 and 24 h and 28 days. Dental discoloration in contact with the cements was assessed after 24 h and 28 and 90 days of contact with bovine and human dentine. Tissue reaction to subcutaneous implantation in rats was examined after 30 and 60 days. RESULTS: AlF3 altered the microstructure of MTA. The addition of 5% AlF3 did not significantly alter the radiopacity, setting time, and volume change (p > 0.05). pH and calcium ion release significantly increased with addition of AlF3 (p > 0.05). All the tested proportions of AlF3 prevented the dental darkening verified for MTA Angelus in bovine and human teeth. AlF3 did not interfere in inflammatory response of MTA in all periods of analysis; otherwise, lower amounts showed less intense inflammatory infiltrate. CLINICAL RELEVANCE: AlF3 prevents destabilization of bismuth oxide and consequent tooth darkening, frequently verified in clinical practice when using white MTA. CONCLUSIONS: The use of 5% of AlF3 in combination to MTA resulted in a cement that did not result in dental discoloration and did not affect significantly physical, chemical, and biological properties.

Doxycycline and Autogenous Bone in Repair of Critical-Size Defects.

PURPOSE: The association of doxycycline (DOX) and autogenous bone on repair of critical-size defects was evaluated. MATERIALS AND METHODS: Fifty albino rats were divided into 5 groups (n = 10). A 5-mm diameter defect was treated with: control (CO)-blood clot; DOX in Natrosol (NAT)-10% gel; NAT-gel; particulate autogenous bone (PAB); and PAB + DOX - PAB associated with 10% DOX gel. The animals were euthanized at 4 and 8 weeks postoperatively. Histomorphometric analysis was performed to assess the percentage of new bone in the defect area. Statistical analysis of the results was performed using analysis of variance and the Tukey test (P < 0.05). RESULTS: The results showed that new bone formation was limited to the margins of the defect. At 4 and 8 weeks, the group PAB + DOX showed higher bone formation (38.59% and 47.86%, respectively), with statistical difference in comparison with the CO (19.52%) at 4 weeks and CO (18.80%), DOX (22.05%), and NAT (15.89%) at 8 weeks (P < 0.05). CONCLUSIONS: The association of 10% DOX with autogenous bone significantly improved bone healing in critical-size defects.

Dental discoloration caused by bismuth oxide in MTA in the presence of sodium hypochlorite.

OBJECTIVES: The aim of this research was to analyse the dental discolouration caused by mineral trioxide aggregate (MTA) induced by bismuth oxide and also assess the colour stability of other dental cements. MATERIALS AND METHODS: Bismuth oxide, calcium tungstate and zirconium oxide were placed in contact with sodium hypochlorite for 24 h after which they were dried and photographed. Phase analyses were performed by X-ray diffraction (XRD) of radiopacifiers before and after immersion in sodium hypochlorite. Furthermore, teeth previously immersed in water or sodium hypochlorite were filled with MTA Angelus, Portland cement (PC), PC with 20 % zirconium oxide, PC with 20 % calcium tungstate and Biodentine. Teeth were immersed for 28 days in Hank's balanced salt solution after which they were sectioned and characterized using scanning electron microscopy (SEM) with energy-dispersive mapping and stereomicroscopy. RESULTS: Bismuth oxide in contact with sodium hypochlorite exhibited a change in colour from light yellow to dark brown. XRD analysis demonstrated peaks for radiopacifier and sodium chloride in samples immersed in sodium hypochlorite. The SEM images of the dentine to material interface showed alteration in material microstructure for MTA Angelus and Biodentine with depletion in calcium content in the material. The energy-dispersive maps showed migration of radiopacifier and silicon in dentine. CONCLUSIONS: MTA Angelus in contact with a tooth previously immersed in sodium hypochlorite resulted in colour alteration at the cement/dentine interface. CLINICAL RELEVANCE: MTA Angelus should not be used after irrigation with sodium hypochlorite as this will result in tooth discoloration.

Antibacterial and dissolution ability of sodium hypochlorite in different pHs on multi-species biofilms.

OBJECTIVES: The aim of this study was to investigate whether variation in pH of sodium hypochlorite (NaOCl) increased its antibacterial and dissolution ability on polymicrobial biofilms formed in situ. MATERIALS AND METHODS: Fifty-six dentin blocks (eight/group) were intraorally infected for 48 h and incubated in BHI for 48 h to standardize the biofilm growth. The specimens were irrigated with 1 and 2.5% NaOCl with pH levels of 5, 7, and 12 for 20 min. The control group was irrigated with distilled water. The cell viability and the bacterial volume were measured at the pre- and post-irrigation procedures. Five random areas of each sample were chosen and analyzed with confocal laser scanning microscopy (CLSM). Statistical analysis was performed using the non-parametric Kruskal-Wallis and Dunn's tests (p < 0.05). RESULTS: All the experimental solutions were able to decrease the biomass (p < 0.05) except for the 1% NaOCl-pH 5 group. The antibacterial ability of the NaOCl was dependent on the concentration and acidification of the solution. CONCLUSIONS: The acidification of NaOCl improves its antibacterial ability, but the dissolution effect of the irrigant is decreased. CLINICAL RELEVANCE: Bacteria and their products are the main factors in development of apical periodontitis. The pH reduction in the NaOCl could enhance the reduction or elimination of the root canal bacterial colonies in comparison with the unaltered solution.

Development of nanobiosilicate, tricalcium phosphate and chlorhexidine materials for biomineralization with crystallographic similarity to hydroxyapatite and biomodified collagen.

OBJECTIVES: The aim of this work is to test experimental cements, doped with a silicate based bioactive nanoparticle (NanoBiosilicate). Methods, we synthesized a glass nanoparticle by Sol-Gel Stöber method, used to be incorporated in a dental material for endodontic uses. MATERIALS AND METHODS: We assess the mineralizing properties and biocompatibility. Besides the crystallography characterization of the resultant new crystals. Results, After analysis, and comparison with commercial materials, the material tested was similar in mechanical properties required by ISO, The ion release was effective after 2 hr. of setting and the novel material was cell compatible accepted by ISO. RESULTS: We found new formed Calcium Phosphate peaks in the spectroscopic analysis (FTIR), remarkably the crystals formed were comparable to hydroxyapatite when analyzed with a Selected Area Electron Diffractometer, with rings of 2.84 Å for 002, and the 2.77 Å is also visible for 210. The 6.83 Å and 6.88 Å, for respective 222 and 004. The incorporation of Chlorhexidine was not detrimental for this property, Significance, the features mentioned represented a progress in biomineralization field that was associated to an improved mineral structure formation with increased crystallographic similarity to natural hydroxyapatite. When chlorhexidine was added a favorable biomodification of the remaining collagen in dentinal walls and antimicrobial activity potential were also observed.

Effect of EDTA Activation on Blood Clot Structure in Regenerative Endodontics: A Scanning Electron Microscopy Study.

INTRODUCTION: EDTA plays a crucial role in regenerative endodontic therapy (RET) because of its significant biological effects. However, EDTA is also recognized as the preferred anticoagulant for hematologic tests. Thus, this study aimed to assess the influence of different EDTA activation techniques on the morphology of blood clots after conditioning the root canal dentin. METHODS: Forty extracted human teeth were prepared to simulate immature teeth and divided into the following 5 groups: (1) saline solution (negative control), (2) EDTA 17% + saline solution (CNI), (3) CNI + ultrasonic activation, (4) CNI + Easy clean activation, and (5) CNI + XP-endo Finisher activation. After irrigation, the roots were cleaved, and the root canals were filled with human blood to clot formation. The morphology and density of erythrocytes, platelets, and the fibrin network were observed using a scanning electron microscope. The fibrin network density was classified using a 4-point scale. Data were analyzed using the Friedman test and the Kruskal-Wallis test with Bonferroni adjustment (α = 5%). RESULTS: All groups exhibited consistent blood clot morphology characterized by a high density of erythrocytes, platelets, and white blood cells throughout the entire length of the root canal. The negative control group showed statistically significant high scores of fibrin density compared with the CNI group in all root thirds (P < .05). However, there was no statistical difference in the scores for the fibrin network density between the groups irrigated with EDTA with and without activation (P > .05). CONCLUSIONS: EDTA may impair the fibrin network formation compared with the saline group. However, EDTA activation did not significantly change the effects on the blood clot in contact with the conditioned intraradicular dentin.

Prevalence and reasons for referrals to the Endodontics Specialty Clinic at the Piracicaba Dental School.

Dental referrals to the Endodontics Specialty Clinic (ESC) are routine owing to the complexity of endodontic treatments. To obtain a better prognosis for treatment, students/dentists must perceive their technical limits. This study sought to investigate the referrals of patients to the ESC from different clinics of the Piracicaba Dental School, State University of Campinas - SP, Brazil, and check: a) the demographic profile of patients and the most commonly affected tooth; b) the clinic with the largest number of referrals; c) the reasons for referrals; d) the complexity of the cases; e) and the difficulty in assessing the referred cases based on the classification provided by the American Association of Endodontists (AAE) and Souza-Filho. The study sample consisted of patients' electronic dental referral records from February 2015 to June 2019. A total of 1,707 patients were referred to the ESC during the study period, and 62.4% were female. Lower molars were the most frequently involved teeth (34.8%), and 60.7% of the cases were referred due to the presence of root curvature. The AAE classification showed prevalence of highly difficult cases (71.3%), whereas Souza-Filho classification demonstrated a high rate of class III cases (85.8%). This study highlights the difficulties encountered by undergraduate students before or during endodontic treatments, reinforcing the need for clear criteria for selecting cases appropriate for each education level, thus improving endodontic treatment prognosis.

Effect of antimicrobial photodynamic therapy on the reduction of bacteria and virulence factors in teeth with primary endodontic infection.

OBJECTIVE: To evaluate the effectiveness of supplemental photodynamic therapy for improving the bacterial removal and the levels of lipopolysaccharide (LPS) and lipoteichoic acid (LTA) by conducting a clinical trial. METHODOLOGY: Twenty-four root canals with pulp necrosis and periapical lesion were selected and randomly divided into conventional group using endodontic treatment with chemo-mechanical preparation (CMP) alone (n = 12) and a group using antimicrobial photodynamic therapy (aPDT) after CMP (n = 12). The samples were collected before and after CMP (conventional group) and after photodynamic therapy (aPDT group). A photosensitizer (0.005% methylene blue) was applied to the root canal for 3 minutes after CMP, whereas aPDT was performed by using a red laser with a power of 30Mw and energy density of 9J/cm2 for 90 s per root canal. Culture technique was performed to determine the bacterial colony forming units. LPS and LTA levels were quantified by using limulus amoebocyte lysate (LAL) assay and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: All samples showed growth of viable bacteria on Fastidious Anaerobe Agar (FAA), with an average of 5.19 × 105 CFU/ mL. CMP was effective in decreasing viable bacteria (p < 0.05), whereas there was a significant decrease (p < 0.05) in the samples treated with aPDT compared to those submitted to CMP. LPS and LTA were detected in all initial samples, with mean values of 20.561 EU/mL and 430.91 pg/mL, respectively. Both CMP and aPDT groups significantly decreased the levels of LPS and LTA (p < 0.05), with a statistical difference between the groups regarding aPDT (p < 0.05). CONCLUSION: Photodynamic therapy as an adjunct to CMP proved to be effective in improving root canal disinfection and reducing the LPS and LTA levels in teeth with primary endodontic infection.

In Vitro Dental Discoloration Provoked by Intracanal Calcium Silicate-based Dressing Used for Regenerative Endodontic Procedures: An One-year Spectrometric Analysis.

INTRODUCTION: Regenerative endodontic procedures provide conditions for the continuity of apical formation and increase of the dentin wall thickness, being a useful technique to resume root development of necrotic teeth with incomplete apex. This study aimed to evaluate the coronal discoloration promoted by a new intracanal calcium silicate-based dressing and compare it with other intracanal dressings used in regenerative endodontic procedures. METHODS: Sixty bovine incisors were prepared to simulate teeth with incomplete apexes and divided according to the intracanal dressing used: triple antibiotic paste-double antibiotic paste-DAP, calcium hydroxide associated with 2% chlorhexidine gel, calcium hydroxide associated with saline solution, and Bio-C Temp. As control, no dressing was performed. The intracanal dressings remained in the simulated root canal for 21 days. Luminosity (ΔL) and color difference (ΔEab and ΔE00) were evaluated using long-term (1 year) spectrophotometric analysis. The results were analyzed using the ANOVA test with Tukey post hoc with a significance of 5%. RESULTS: Triple antibiotic paste showed the highest values of ΔEab and ΔE00 and lowest values of ΔL (P < .05). Bio-C Temp showed higher ΔEab than the other groups from 6 months (P < .05), higher ΔE00 and lower ΔL after 1 year (P < .05). CONCLUSIONS: Bio-C Temp induced noticeable coronary discoloration after the 1-year analysis.

Clinical evaluation of culturable bacteria, endotoxins and lipoteichoic acid in teeth with vital normal pulp tissues.

The objective of this study was to investigate the presence of culturable bacteria, endotoxins (LPS) and lipoteichoic acid (LTA) levels in teeth with normal vital pulp (NVP) with intact crowns (IC) and those with coronal restoration (CR) limited to the enamel level. A total of 20 teeth indicated for endodontic treatment due to prosthetic reasons were selected. Samples were collected from the root canals. The levels of cultivable bacteria, LPS and LTA were assessed. Statistical analyses were performed at significance level set at 5%. None of the teeth presented microbial growth. In the IC group, the LPS levels were limited to the lowest concentration of LPS. On the contrary, higher LPS and LTA levels were detected in teeth with CR. It was concluded that teeth with NVP and IC were negative for bacteria, LPS and LTA; while teeth with CR were positive for bacterial virulence factors.

Physico-chemical properties of calcium silicate-based sealers in powder/liquid and ready-to-use forms.

Calcium silicate-based root canal sealers have been developed in powder/liquid or premixed ready-to-use forms. The evaluation of the physico-chemical properties of a prototype powder/liquid MTApex Sealer (Ultradent) in comparison to a ready-to-use material EndoSequence BC Sealer (Brasseler) was performed. The paste/paste epoxy resin-based AH Plus (Dentsply) served as control for comparisons. The sealers were evaluated (n = 6) regarding setting time (in dry and moist environments), flow and radiopacity, following the ISO-6876/2012 standard. Also, the pH was assessed. Material's surface and chemical characterization was evaluated using scanning-electron-microscopy (SEM) and energy-dispersive-spectrometry (EDS). Mixed ANOVA, Shapiro-Wilk, Levene, and post-hoc analysis with Bonferroni correction were performed at a significance level of 5%. MTApex Sealer exhibited the highest flow and EndoSequence BC Sealer had a significantly longer setting time in dry compared to the moist environment; however, for MTApex Sealer and AH Plus no significant changes occurred when additional moisture was provided. All materials exceeded 7 mm Al of radiopacity and showed a decreasing alkalinity over the 21 day-analysis. SEM/EDS evaluation resulted in peaks of calcium, silicon, and the respective radiopacifier. The prototype powder/liquid MTApex Sealer had the highest flow and similar setting time in both dry and moist environments; opposingly, EndoSequence BC Sealer was crucially influenced by external moisture. This suggests that the powder/liquid materials' setting seems to be more predictable.