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.

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 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.

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.

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

Abstract 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.

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.

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.

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.

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.

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.

Effects of Bismuth Exposure on the Human Kidney-A Systematic Review.

The effects of bismuth toxicity on the kidney-the main organ responsible for blood filtration-were systematically reviewed. This review was motivated by availability of several sources of bismuth in contact with humans including environmental, medications, dental materials, and cosmetics, potentially leading to kidney filtration of this chemical. No previous studies have systematically reviewed the literature considering this association. A total of 22 studies with a total of 46 individuals met the inclusion criteria, 19 being case reports with only one patient enrolled. The included studies publication dates ranged from 1961 to 2021 and the countries of publication were the United States of America, United Kingdom, Germany, Turkey, Switzerland, and Canada. Bismuth sources affecting the kidneys were uniquely reported as from medical purposes and mostly associated to overdoses with several symptoms, apparently with dose-dependent consequences. Patient history of renal impairment seemed to affect the outcome of the case. Several therapies were conducted following bismuth intoxication, and few studies performed renal biopsies describing its histological findings. It is crucial to reconsider the nephrotoxicity of bismuth compounds, mainly in patients with previous history of renal impairment.

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.

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

Abstract 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.

Resumo Os cimentos endodônticos obturadores à base de silicato de cálcio foram desenvolvidos em formas pó/líquido ou pré-misturadas prontas para o uso. Foi realizada a avaliação das propriedades físico-químicas de um protótipo pó/líquido MTApex Sealer (Ultradent) em comparação com um material pronto para uso EndoSequence BC Sealer (Brasseler). O cimento obturador pasta/pasta à base de resina epóxi AH Plus (Dentsply) serviu de controle para as comparações. Os cimentos foram avaliados (n = 6) quanto a: tempo de presa (em ambientes secos e úmidos), escoamento e radiopacidade, seguindo a norma ISO-6876/2012; como também o pH. A superfície do material e a caracterização química foram realizadas utilizando a microscopia eletrônica de varredura (MEV) e espectrometria dispersiva de energia (EDS). ANOVA, Shapiro-Wilk, Levene e análise post-hoc com correção de Bonferroni foram realizadas com nível de significância de 5%. O MTApex Sealer exibiu um escoamento mais alto e o EndoSequence BC Sealer teve um tempo de presa significativamente mais longo em ambiente seco em comparação com o ambiente úmido; entretanto, para MTApex Sealer e AH Plus, nenhuma mudança significativa ocorreu quando umidade adicional foi fornecida. Todos os materiais excederam 7 mm de Al de radiopacidade e mostraram uma alcalinidade decrescente ao longo dos 21 dias de análise. A avaliação MEV/EDS resultou em picos de cálcio, silício e respectivo radiopacificador. O protótipo de pó/líquido MTApex Sealer teve o maior escoamento e tempo de presa semelhante em ambientes secos e úmidos; ao contrário, o EndoSequence BC Sealer foi influenciado de maneira crucial pela umidade externa. Isso sugere que a configuração dos materiais em pó/líquido parece ser mais previsível.

Influence of working length and anatomical complexities on the apical root canal filling: a nano-CT study

Abstract The present study aimed to compare the filled volume by gutta-percha and sealer in the apical region of the main canal and ramifications, after instrumentation at two different working lengths using nano-computed tomography (nano-CT). Twenty-two premolars with apical ramifications were selected after micro-computed tomography evaluation and were randomly divided into groups for further endodontic instrumentation at two different working lengths: G1 - Root canals shaped 1 mm short of the apical foramen (n=11), and G2 - Root canals shaped at the apical foramen (n=11). After completing root treatment, nano-CT images were acquired, and the filled volume by gutta-percha and sealer in the main canal apical 0-4 mm and 0-1 mm ranges, and apical ramifications were objectively measured by an operator specialized in both radiology and endodontics, blinded for both groups. The Mann-Whitney test was applied to compare both groups regarding the filling of the main canal apical ranges and apical ramifications with a significance level of 5% (α ≤ 0.05). It was observed that root canals shaped at the apical foramen had a larger volume of the main canal filled than root canals shaped 1 mm short of the apical foramen, at both apical ranges (0-4 and 0-1 mm) (p<0.05). Regarding the filling of the apical ramifications, there was no significant difference between groups (p>0.05). In conclusion, the root canals shaped at apical foramen exhibited increased filling volume of the main canal in the apical region. However, neither of both working lengths influenced filling of the apical ramifications.

Resumo O presente estudo teve como objetivo comparar o volume preenchido por guta-percha e cimento na região apical do canal principal e ramificações, após instrumentação em dois comprimentos de trabalho diferentes, por meio de nano tomografia computadorizada (nano-TC). Vinte e dois pré-molares com ramificações apicais foram selecionados após avaliação por micro-tomografia computadorizada e foram divididos aleatoriamente em grupos para posterior instrumentação endodôntica em dois comprimentos de trabalho diferentes: G1 - Canais radiculares instrumentados 1 mm aquém do forame apical (n = 11) e G2 - Canais radiculares instrumentados até o forame apical (n = 11). Após a obturação dos canais radiculares, imagens de nano-CT foram adquiridas, e o volume preenchido por guta-percha e cimento nas faixas apicais de 0-4 mm e 0-1 mm do canal principal, e ramificações apicais, foram avaliadas objetivamente por um especialista em radiologia e endodontia, cego para ambos os grupos. O teste de Mann-Whitney foi aplicado para comparar os dois grupos quanto ao preenchimento das faixas apicais do canal principal e ramificações com nível de significância de 5% (α ≤ 0,05). Observou-se que canais radiculares instrumentados até o forame apical apresentaram maior volume do canal principal preenchido do que canais radiculares instrumentados 1 mm aquém do forame apical, em ambas as faixas apicais (0-4 e 0-1 mm) (p <0,05) Em relação ao preenchimento das ramificações apicais, não houve diferença significativa entre os grupos (p> 0,05). Em conclusão, os canais radiculares instrumentados até o forame apical mostraram um maior volume de preenchimento na região apical do canal principal. No entanto, os dois diferentes comprimentos de trabalho não influenciaram o preenchimento das ramificações apicais.

Can strontium replace calcium in bioactive materials for dental applications?

The substitution of calcium with strontium in bioactive materials has been promising but there has been some concern over the material instability and possible toxicity. The aim of this research was the synthesis and characterization of calcium and strontium substituted bioactive materials and assessment of interactions with local tissues and peripheral elemental migration in an animal model. A bioactive glass, hydroxyapatite and hydraulic calcium silicate with 50% or 100% calcium substitution with strontium were developed and the set materials were characterized immediately after setting and after 30 and 180-days in solution. Following subcutaneous implantation, the local (tissue histology, elemental migration) and systemic effects (elemental deposition after organ digestion) were assessed. The strontium-replaced silicate cements resulted in the synthesis of partially substituted phases and strontium leaching at all-time points. The strontium silicate implanted in the animal model could not be retrieved in over half of the specimens showing the high rate of material digestion. Tissue histology showed that all materials caused inflammation after 30 days of implantation however this subsided and angiogenesis occurred after 180 days. Strontium was not detected in the local tissues or the peripheral organs while all calcium containing materials caused calcium deposition in the kidneys. The tricalcium silicate caused elemental migration of calcium and silicon in the local tissues shown by the elemental mapping but no deposition of calcium was identified in the peripheral organs verified by the assessment of the digested tissues. Strontium can substitute calcium in bioactive materials without adverse local or systemic effects.

Influence of working length and anatomical complexities on the apical root canal filling: a nano-CT study.

The present study aimed to compare the filled volume by gutta-percha and sealer in the apical region of the main canal and ramifications, after instrumentation at two different working lengths using nano-computed tomography (nano-CT). Twenty-two premolars with apical ramifications were selected after micro-computed tomography evaluation and were randomly divided into groups for further endodontic instrumentation at two different working lengths: G1 - Root canals shaped 1 mm short of the apical foramen (n=11), and G2 - Root canals shaped at the apical foramen (n=11). After completing root treatment, nano-CT images were acquired, and the filled volume by gutta-percha and sealer in the main canal apical 0-4 mm and 0-1 mm ranges, and apical ramifications were objectively measured by an operator specialized in both radiology and endodontics, blinded for both groups. The Mann-Whitney test was applied to compare both groups regarding the filling of the main canal apical ranges and apical ramifications with a significance level of 5% (α ≤ 0.05). It was observed that root canals shaped at the apical foramen had a larger volume of the main canal filled than root canals shaped 1 mm short of the apical foramen, at both apical ranges (0-4 and 0-1 mm) (p<0.05). Regarding the filling of the apical ramifications, there was no significant difference between groups (p>0.05). In conclusion, the root canals shaped at apical foramen exhibited increased filling volume of the main canal in the apical region. However, neither of both working lengths influenced filling of the apical ramifications.

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.