A three-dimensional cell culture approach to investigate cytotoxic effects and production of inflammatory mediators by epoxy resin-based and calcium silicate-based endodontic sealer.

OBJECTIVES: The aim of the present study was to assess the cytocompatibility of epoxy resin-based AH Plus Jet (Dentsply De Trey, Konstanz, Germany), Sealer Plus (MK Life, Porto Alegre, Brazil), calcium silicate-based Bio-C Sealer (Angelus, Londrina, PR, Brazil), Sealer Plus BC (MK Life) and AH Plus BC (Dentsply) through a tridimensional (3D) culture model of human osteoblast-like cells. METHODS: Spheroids of MG-63 cells were produced and exposed to fresh root canal sealers extracts by 24 h, and the cytotoxicity was assessed by the Lactate Dehydrogenase assay (LDH). The distribution of dead cells within the microtissue was assessed by fluorescence microscopy, and morphological effects were investigated by histological analysis. The secreted inflammatory mediators were detected in cell supernatants through flow luminometry (XMap Luminex). RESULTS: Cells incubated with AH Plus Jet, AH Plus BC, Sealer Plus BC and Bio-C Sealer extracts showed high rates of cell viability, while the Sealer Plus induced a significant reduction of cell viability, causing reduction on the spheroid structure. Sealer Plus and Seaker Plus BC caused alterations on 3D microtissue morphology. The AH Plus BC extract was associated with the downregulation of secretion of pro-inflammatory cytokines IL-5, IL-7, IP-10 and RANTES. CONCLUSIONS: The new AH Plus BC calcium silicate-based endodontic sealer did not reduce cell viability in vitro, while led to the downregulation of pro-inflammatory cytokines. CLINICAL SIGNIFICANCE: Choosing the appropriate endodontic sealer is a crucial step. AH Plus BC demonstrated high cell viability and downregulation of pro-inflammatory cytokines, appearing reliable for clinical use, while Sealer Plus presented lower cytocompatibility.

Evaluation of Inflammatory Response to Endodontic Sealers in a Bone Defect Animal Model.

AIM: The aim of this study was to evaluate the inflammatory response to MTA Fillapex, AH Plus, and Pulp Canal Sealer Extensive Work Time (EWT), in a murine bone defect grafting model. MATERIALS AND METHODS: Bilateral mandibular critical defects were produced in 45 Wistar rats with a trephine bur#2 and filled with the endodontic sealers. After 7, 14, and 28 days, the rats were euthanized and their jaws were histologically prepared. RESULTS: For the 7-day group, no statistical significance was observed among all studied groups (p > 0.05), and high levels of inflammatory infiltrate were detected. After 14 and 28 days, Pulp Canal Sealer EWT showed statistically lower inflammatory response in comparison to other sealers (p < 0.05) except for the control group (no sealers). CONCLUSION: Pulp Canal Sealer EWT presented the lowest levels of inflammatory response. The critical defect grafting model was an effective method to detect differences among differences on the biological response to endodontic sealers. CLINICAL SIGNIFICANCE: Knowing the biocompatibility of endodontics sealers that will be used in filling the root canal.

Is There a Relationship between Laser Therapy and Root Canal Cracks Formation? A Systematic Review.

Introduction: Crack formation has become an important issue for endodontists, as it can be decisive for the long-term prognosis of the endodontically treated tooth. Since the applicability of laser in endodontics has become frequent, this systematic review aimed to evaluate the association between laser therapy and the formation of cracks in the dentinal structure of the root canal. Materials and Methods: A search was performed in PubMed, Scopus, Web of Science, and Virtual Health Library, as well as in the gray literature, on September 24, 2021. Studies that evaluated the formation of cracks in human root dentin due to different types of lasers were included. The risk of bias was assessed following the modified version of the Consolidated Standards of Reporting Trials (CONSORT) checklist tool. A meta-analysis was performed to evaluate (i) the total number of crack incidences; (ii) complete crack formation; (iii) incomplete crack formation; (iv) intra-dentinal crack formation between ultrasonic tips and laser use. The mean difference was calculated with a 95% confidence interval in a fixed-effect model, the heterogeneity was tested using the I2 index with level of significance of 5%. Results: Of the 22 studies included in this review, 15 have shown that lasers can form cracks in root dentin, including those that performed baseline assessment of samples. The meta-analysis confirmed no difference in crack formation between ultrasonic tips and laser devices. Conclusions: Laser therapy has been gaining prominence in endodontics and that irradiation can form and propagate cracks in the dentinal structure of the root canal assessed by in vitro studies. This is a critical concern for endodontists as it affects the strength and longevity of the tooth. Future research is encouraged to seek the standardization of good methodological practices and achieve establishing parameters to minimize harmful effects of laser on dentin.

Noncontact 3D evaluation of surface topography of reciprocating instruments after retreatment procedures.

This study evaluated the Reciproc R25 and Pro-R 25 instruments in unused condition, after one and a second use in endodontic retreatment employing a noncontact 3D light interferometer profiler, scanning electron microscopy (SEM) and cyclic fatigue tests. Twenty single-root teeth were instrumented with Reciproc R25 and filled with gutta-percha and sealer. A 3D profiler with a 20x objective using the Mx™ software was used to evaluate the cutting blade surfaces of Reciproc R25 and Pro-R 25 (n=5 per group) in unused condition, after the first and second uses in retreatment procedures. After retreatment, SEM was used to evaluate the topographic features of the used instruments. Cyclic fatigue tests were performed to compare new to used instruments. One-way ANOVA followed by Tukey test was used to compare the tested instruments before and after the first and second uses. Student t-test was used to compare the different instruments and for cyclic fatigue evaluation. No significant differences were observed in the cutting blade surfaces of Reciproc and Pro-R before and after one and two uses (p>0.05). Reciproc without use showed higher Sa and Sq when compared to Pro-R without use (p<0.05). No differences were observed between Reciproc and Pro-R after one and two uses (p>0.05). New and unused Reciproc showed longer time to fracture than Pro-R instruments (p<0.05), and only Pro-R showed differences between new and used instruments (p<0.05). Retreatment procedures with Reciproc and Pro-R did not change the surface topography of instruments. Reciproc had greater resistance to cyclic fatigue compared with Pro-R.

Cytocompatibility and antimicrobial activity of a novel endodontic irrigant combining citric acid and chlorhexidine.

OBJECTIVES: This study aimed to evaluate the antibacterial ability and cytocompatibility of a new irrigant solution for endodontic treatment composed of 10% citric acid (CA) and 1% chlorhexidine (CHX). METHODS: Thirty-five extracted single-canal human teeth were selected and de-crowned. Canal systems (n = 7/group) were infected with Enterococcus faecalis for 4 weeks and subject to irrigation with 1% CHX; 10% CA; irrigating solution 10% CA associated with 1% CHX (CACHX); 2.5% NaOCl or sterile water (control). Microbiological samples were collected immediately and 18 h after irrigation (enriched samples). The canals were filled with culture medium post irrigation to verify the bacterial presence/absence qualitatively and quantitatively through colony counting (log10 CFU/mL). A multiparametric assay was performed after exposure of human periodontal ligament fibroblasts (HPdLF) to the test solutions. The Kruskal-Wallis test with Dunn´s post-test and Fisher's exact test were employed at the 95% confidence level to compare differences among groups. RESULTS: All tested solutions were cytocompatible with human periodontal ligament fibroblasts. No difference was observed on antibacterial activity between 1% CHX, 10% CA, CACHX and 2.5% NaOCl (p > 0.05). Eighteen hours after irrigation, CACHX samples were the only that did not present E. faecalis in the root canal system. CONCLUSIONS: The demonstrated good in vitro biocompatibility and elimination of E. faecalis suggest a potential use of 10% CA associated with 1% CHX as a solution for microbiological control during endodontic treatment. CLINICAL RELEVANCE: Irrigants play an essential role during endodontic therapy. This irrigating solution, based on the association of 10% citric acid with 1% chlorhexidine, seems viable for clinical procedures.

Prognosis of Regenerative Endodontic Procedures in Mature Teeth: A Systematic Review and Meta-Analysis of Clinical and Radiographic Parameters.

This work aimed to investigate the use of Regenerative Endodontic Procedures (REP) on the treatment of pulp necrosis in mature teeth through systematic review and meta-analysis of evidence on clinical and radiographic parameters before and after REP. A search was performed in different databases on 9 September 2020, including seven clinical studies and randomized controlled trials (RCT). The methodological quality was assessed using Revised Cochrane risk-of-bias (RoB 2) and Before-and-After tools. Meta-analyses were performed to evaluate the success incidences regarding the reduction of periapical lesion and recovery of sensitivity. The certainty of the evidence was assessed using GRADE. Meta-analysis showed a high overall success of 0.95 (0.92, 0.98) I2 = 6%, with high periapical lesion reduction at 12 months (0.93 (0.86, 0.96) I2 = 37%) and by the end of follow-up (0.91 (0.83, 0.96) I2 = 13%). Lower incidences of positive sensitivity response were identified for the electrical (0.58 (0.46, 0.70) I2 = 51%) and cold tests (0.70 (0.54, 0.84) I2 = 68%). The calculated levels of REP success were similar to those reported for immature teeth. With a very low certainty of evidence, the meta-analysis showed a high incidence of REP's success for mature teeth with necrotic pulp evidenced by periapical lesion reduction and moderate positive responses to sensitivity tests.

The influence of medication on salivary flow of the elderly: preliminary study.

OBJECTIVE: This study was to evaluate the influence of medications on unstimulated and stimulated salivary flow in elderly men and women. BACKGROUND: Several diseases and conditions are associated with decreasing salivary flow. Medications can be risk factors for hyposalivation due to the effect particular drug categories. METHODS: Seventy-five elderly of both gender (sixty years old or over) from the Geriatric Dental Clinic at the Federal Fluminense University Dental School, were interviewed about their health status and chronic use of medication. After the interview, unstimulated and stimulated saliva were collected from each subject. The collection time was five minutes, and the flow rate was calculated as ml/min. RESULTS: The mean unstimulated salivary flow was 0.25 ml/min for women and 0.30 ml/min for men, while the mean for stimulated salivary flow was 1.23 ml/min for women and 1.31 ml/min for men, without both differences being non-significant (p > 0.05). The difference between the mean production of unstimulated and stimulated salivary flow was statistically significant, regardless of gender (p < 0.01). A significant reduction of stimulated salivary flow was observed with the usage of cardiovascular agents (p < 0.05). CONCLUSION: Drugs used in cardiovascular disease influence the flow of stimulated saliva.

Structural Analysis of NiTi Endodontic Instruments: A Systematic Review.

Introduction: Irregularities and defects on NiTi endodontic instruments originating from the manufacturing process can lead to the structural collapse and fracture of these instruments during treatment. To assess the cause of instrument wear and fracture, as well as increasing fracture incidence, destructive and non-destructive methods have been used for the analysis of surfaces and internal structures of new and used NiTi instruments. The aim of this systematic review was to undertake a detailed analysis of the methods used to evaluate the surface and internal microstructure of endodontic instruments. Methods and Materials: The scientific literature was comprehensively and systematically searched in the MEDLINE (PubMed), Web of Science, Cochrane Library, Scopus, and LILACS/BBO databases for studies published up to June 9, 2019. The eligibility criteria was based on the PICO (Patient, Intervention, Comparison, and Outcome) strategy with the question "What is the best method for structural analysis of endodontic files?" Two aspects were considered for inclusion in this study: (i) endodontic instruments and (ii) methods for structural analysis of NiTi instruments. . The systematic review was performed according to the PRISMA statement. Results: Based on the inclusion criteria, 94 articles were selected. The results showed that although specific methods have been used for qualitative and/or quantitative structural analysis of NiTi instruments, no study addressed both the surface and internal structure of the instruments at the same time. According to this review, the need to compare the methodologies used in the selected articles has been identified; however, each type of method used has its own limitation on the analysis of both the surface and the internal structure of the instruments. Conclusions: The comparison between the different types of methodologies used in the studies revealed the reliability and the limitations of the methods employed for structural analysis of endodontic instruments; thus assisting us in determining their validity.

Association of DNA sequence-independent genetic regulatory mechanisms with apical periodontitis: A scoping review.

OBJECTIVE: Different studies in the last decade have proposed that gene expression alterations that are independent of the DNA sequence may also play an important role in periapical disease. The present study aimed to assess the available evidence supporting a relationship between these alterations and apical periodontitis through a scoping review. DESIGN: Specific strategies were developed for different databases (MEDLINE via PubMed, Cochrane Library, Scopus, Web of Science, and Virtual Health Library) and a search performed by March 1st, 2019. The evidence sources were selected according to the eligibility criteria and underwent a critical appraisal of methodological quality. RESULTS: The initial search retrieved 212 references, with eight eligible articles after the removal of replicates and application of exclusion criteria. Five studies identified altered DNA methylation on inflammatory response genes (FOXP3, CXCL3, FADD, MMP2, MMP9, IFNG, IL4, IL12) on AP patients. Three others identified the alterations on the expression of several microRNAs (miR-29b, 106b, 125b, 143, 146a, 155, 198) during AP. No evidence was identified regarding mechanisms of histone methylation, or of epigenetic heritability or stability. CONCLUSIONS: There is available evidence for the involvement of different genetic regulatory mechanisms independent of changes in DNA sequence in the development or severity of apical periodontitis. However, due to methodological limitations, further research must be performed before novel therapies and diagnostic tools for AP may arise from these data.

In vitro cytotoxicity of dental adhesives: A systematic review.

OBJECTIVES: The increased demand for esthetics and minimally invasive tooth restorations resulted in a rapid development of adhesive dentistry. However, much controversy remains about the safe use and cytotoxic effects of different groups of dental adhesives. The present study performed a systematic review to identify the answer to the following question: are self-etch adhesives more cytotoxic than those employing the etch-and-rinse system? METHODS: This systematic review was performed in accordance with the PRISMA statement; a quality assessment for in vitro studies was conducted using the ToxRTool. Specific search strategies were developed and performed in the electronic databases MEDLINE via PubMed, Cochrane Library, Scopus, Web of Science, and LILACS/BBO. After removal of duplicated studies and application of the exclusion criteria, ten eligible articles were selected and submitted to a qualitative descriptive analysis comparing both groups of dental adhesives. Most in vitro test systems employed pulp cells or gingival fibroblasts. RESULTS: The methodologies presented great variability regarding the exposure to the test materials. Only four studies assessed the role of the degree of conversion of the materials in their toxicity, with conflicting results. SIGNIFICANCE: While the lack of methodological standardization among the studies still hinders the establishment of a relationship between type of dental adhesive and toxicity, studies employing dentin barrier systems indicate greater cytotoxicity for etch-and-rinse adhesives.

Noncontact three-dimensional evaluation of surface alterations and wear in NiTi endodontic instruments.

The aim of this study was to undertake a qualitative and quantitative assessment of nanoscale alterations and wear on the surfaces of nickel-titanium (NiTi) endodontic instruments, before and after use, through a high-resolution, noncontact, three-dimensional optical profiler, and to verify the accuracy of the evaluation method. Cutting blade surfaces of two different brands of NiTi endodontic instruments, Reciproc R25 (n = 5) and WaveOne Primary (n = 5), were examined and compared before and after two uses in simulated root canals made in clear resin blocks. The analyses were performed on three-dimensional images which were obtained from surface areas measuring 211 × 211 µm, located 3 mm from their tips. The quantitative evaluation of the samples was conducted before and after the first and second usage, by the recordings of three amplitude parameters. The data were subjected to statistical analysis at a 5% level of significance. The results revealed statistically significant increases in the surface wear of both instruments groups after the second use. The presence of irregularities was found on the surface topography of all the instruments, before and after use. Regardless of the evaluation stage, most of the defects were observed in the WaveOne instruments. The three-dimensional technique was suitable and effective for the accurate investigation of the same surfaces of the instruments in different periods of time.

Noncontact 3D evaluation of surface topography of reciprocating instruments after retreatment procedures

Abstract This study evaluated the Reciproc R25 and Pro-R 25 instruments in unused condition, after one and a second use in endodontic retreatment employing a noncontact 3D light interferometer profiler, scanning electron microscopy (SEM) and cyclic fatigue tests. Twenty single-root teeth were instrumented with Reciproc R25 and filled with gutta-percha and sealer. A 3D profiler with a 20x objective using the Mx™ software was used to evaluate the cutting blade surfaces of Reciproc R25 and Pro-R 25 (n=5 per group) in unused condition, after the first and second uses in retreatment procedures. After retreatment, SEM was used to evaluate the topographic features of the used instruments. Cyclic fatigue tests were performed to compare new to used instruments. One-way ANOVA followed by Tukey test was used to compare the tested instruments before and after the first and second uses. Student t-test was used to compare the different instruments and for cyclic fatigue evaluation. No significant differences were observed in the cutting blade surfaces of Reciproc and Pro-R before and after one and two uses (p>0.05). Reciproc without use showed higher Sa and Sq when compared to Pro-R without use (p<0.05). No differences were observed between Reciproc and Pro-R after one and two uses (p>0.05). New and unused Reciproc showed longer time to fracture than Pro-R instruments (p<0.05), and only Pro-R showed differences between new and used instruments (p<0.05). Retreatment procedures with Reciproc and Pro-R did not change the surface topography of instruments. Reciproc had greater resistance to cyclic fatigue compared with Pro-R.

Resumo Este estudo avaliou os instrumentos Reciproc R25 e Pro-R 25 sem uso, após um primeiro e um segundo uso em retratamento endodôntico com perfilômetro 3D por interferometria de luz sem contato, microscópio eletrônico de varredura (MEV) e testes de fadiga cíclica. Vinte dentes unirradiculares foram instrumentados com Reciproc R25 e obturados com guta-percha e cimento endodôntico. Um perfilômetro 3D com uma objetiva 20x usando o software Mx ™ foi usado para avaliar as superfícies da lâmina de corte do Reciproc e Pro-R (n = 5 por grupo) na condição sem uso, após o primeiro e após um segundo uso em procedimentos de retratamento. Após retratamento, o MEV foi usado para avaliar as características topográficas dos instrumentos utilizados. Testes de fadiga cíclica foram realizados para comparar instrumentos novos com instrumentos usados. O teste One-way ANOVA seguido pelo teste de Tukey foi usado para comparar os instrumentos testados nos diferentes estágios. Para comparar os diferentes instrumentos e para avaliação de fadiga cílcica, foi utilizado o Student t-test. Não foram observadas diferenças estatisticamente significantes nas superfícies das lâminas de corte dos instrumentos Reciproc e Pro-R antes e após um e dois usos (p> 0,05). O Reciproc na condição sem uso apresentou maior Sa e Sq quando comparado ao Pro-R (p <0,05). Não foram observadas diferenças entre Reciproc e Pro-R após um e dois usos (p> 0,05). O Reciproc sem uso apresentou maior tempo de fratura do que os instrumentos Pro-R (p<0,05), e apenas o Pro-R apresentou diferenças entre instrumentos novos e usados (p<0,05). Os procedimentos de retratamento com Reciproc e Pro-R não alteraram a topografia da superfície dos instrumentos. Reciproc apresentou maior resistência à fadiga cíclica em comparação com o Pro-R.

Effect of Citric Acid and Ethylenediaminetetraacetic Acid on the Surface Morphology of Young and Old Root Dentin.

INTRODUCTION: The aim of this in vitro study was to evaluate the effect of 10% citric acid and 17% ethylenediaminetetraacetic acid (EDTA) irrigating solutions on the surface morphology of young and old root dentin by determining the number and diameter of dentinal tubules using scanning electron microscopy (SEM). METHODS AND MATERIALS: Fifty healthy human teeth collected from young (≤30 years) and old (≥60 years) individuals (n=25) were first prepared with a Largo bur #2 to produce smear layer on the root canal surface. Subsequently, the crowns and the root middle and apical thirds were sectioned and removed, and the cervical thirds were sectioned vertically in the buccal-lingual direction into two equal halves. The obtained samples were then immersed in 2.5% sodium hypochlorite for 30 min and randomly separated into two treatment groups for each age group. In each age group, ten samples were selected as controls and did not receive any type of treatment. The rest of the specimens were then rinsed, dried and treated for 4 min with 10% citric acid or 17% EDTA. The samples were then assessed with SEM regarding the number and diameter of dentinal tubules. All data were assessed using Student's t-test. The level of significance was set at 0.05. RESULTS: Regardless of the type of treatment, no significant differences were observed in the number of open tubules between the young and old root dentin (P>0.05). Nonetheless, the diameter of the tubules in the old root dentin was larger when 17% EDTA was used (P<0.05). Both, young and old root dentin did not differ with the 10% citric acid treatment (P>0.05). CONCLUSION: The results showed that 17% EDTA treatment induced a significant demineralization in old root dentin.

A comparison of two reciprocating instruments using bending stress and cyclic fatigue tests.

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 mm in length, were tested. The bending resistance was evaluated through the results of a cantilever-bending test conducted using a universal testing machine. Static and dynamic cyclic fatigue testing was conducted using a custom-made device. For the static and dynamic tests, a cast Ni-Cr-Mo-Ti alloy metal block with an artificial canal measuring 1.77 mm in diameter and 20.00 mm in total length was used. A scanning electron microscope was used to determine the type of fracture. Statistical analyses were performed on the results. The WaveOne instrument was less flexible than the Reciproc (p < 0.05). The Reciproc instrument showed better resistance in the static and dynamic cyclic fatigue tests (p < 0.05). The transverse cross-section and geometry of the instruments were important factors in their resistance to bending and cyclic fracture. Both of the instruments showed ductile-type fracture characteristics. It can be concluded that the Reciproc 25-08 instrument was more resistant to static and dynamic cyclic fatigue than the WaveOne 25-08 instrument, while the WaveOne 25-08 instrument was less flexible. Bending and resistance to cyclic fracture were influenced by the instruments' geometries and transverse cross-sections. Both of the instruments showed ductile-type fracture characteristics.

Decalcifying effect of EDTA-T, 10% citric acid, and 17% EDTA on root canal dentin.

OBJECTIVE: An in vitro study was conducted to determine the efficacy of 17% EDTA plus 1.25% sodium lauryl ether sulfate (EDTA-T), 10% citric acid, and 17% EDTA with respect to Ca(++) extraction. STUDY DESIGN: The root canals of 90 extracted human canines were instrumented by using the step-back technique. The teeth were randomly divided into 9 groups of 10 teeth each according to the solution and time intervals involved (ie, 3, 10, and 15 minutes). The Ca(++) concentration of the solution was determined by using atomic absorption spectroscopy. RESULTS: At 3 minutes, there was no significant difference between Ca(++) extraction by 10% citric acid and 17% EDTA (P >.05). EDTA-T had the least efficacy for Ca(++) extraction (P <.05). At 10 minutes and 15 minutes, there were no significant differences between 10% citric acid and 17% EDTA or between EDTA-T and 17% EDTA (P >.05). However, 10% citric acid was significantly better than EDTA-T in terms of Ca(++) extraction (P <.05). CONCLUSION: Both 10% citric acid and 17% EDTA are good decalcifying agents when the step-back technique is used.

Effect of three different time periods of irrigation with EDTA-T, EDTA, and citric acid on smear layer removal.

OBJECTIVE: An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid on the removal of smear layer from root canal dentin after final irrigation for 3, 10, and 15 min. STUDY DESIGN: Root canals of 90 extracted human canines were divided into 9 groups of 10 teeth; each group received a final irrigation with one of the irrigants for the established time intervals. After irrigation, the teeth were split and prepared for SEM analysis to determine the number of open dentinal tubules. RESULTS: There were statistically significant better results (P <.05) when irrigation with 10% citric acid for 3 min was compared to 10 and 15 min, and when irrigation with EDTA for 3 min was compared to 15 min. In all cases, irrigation for 3 min presented the greatest number of open dentinal tubules. There were no significant differences (P>.05) for the 3 time intervals of irrigation for EDTA-T, although there were a greater number of open tubules at 3 min. CONCLUSION: These 3 irrigants were effective at the shortest time tested and did not demonstrate an improved effect with an increase in time.

Bond Strength Evaluation of Two Adhesive Systems in Fiberglass Posts Cementation

Objective: To compare the bond strength of three-step and self-etch adhesive systems with and without prior acid etching on bonding of fiberglass posts in root canals. Material and Methods: Experiments were conducted on roots of five upper molars without curvature and sectioned in a cervical-apical direction. With the aid of a highspeed turbine and diamond tips, cylindrical cavities 7 mm in depth and 1.4 mm in diameter were made in the dentine. The roots of the same tooth were used, where the retainers were cemented, thus generating three groups: Group A: Adper Scotchbond Multipurpose Plus (SBMP) + Rely X ARC; Group B: Single Bond Universal (SBU-1) + Rely X ARC, with acid etching prior to adhesive insertion; Group C: Single Bond Universal (SBU-2) + Rely X ARC. The samples were stored in a bacteriological incubator at 37ºC with 100% humidity for 48h and were subsequently cross-sectioned to obtain 3 dentine discs 1mm in thickness. Forty-five specimens were subjected to the push-out test. Results: Through the analysis of variance and Tukey's test, it was found that SBMP showed, with statistical significance (p<0.05), highest bond strength when compared with the SBU-1 and SBU-2 systems. The observed difference in the discs was located in the cervical portion. Conclusion: The three-step adhesive system had higher bond strength with the substrate than the self-etching adhesive only in the disc in the cervical portion; further, statistically, the prior application of phosphoric acid in SBU-1 did not affect its bond strength significantly.

Noncontact three-dimensional evaluation of surface alterations and wear in NiTi endodontic instruments

Abstract The aim of this study was to undertake a qualitative and quantitative assessment of nanoscale alterations and wear on the surfaces of nickel-titanium (NiTi) endodontic instruments, before and after use, through a high-resolution, noncontact, three-dimensional optical profiler, and to verify the accuracy of the evaluation method. Cutting blade surfaces of two different brands of NiTi endodontic instruments, Reciproc R25 (n = 5) and WaveOne Primary (n = 5), were examined and compared before and after two uses in simulated root canals made in clear resin blocks. The analyses were performed on three-dimensional images which were obtained from surface areas measuring 211 × 211 µm, located 3 mm from their tips. The quantitative evaluation of the samples was conducted before and after the first and second usage, by the recordings of three amplitude parameters. The data were subjected to statistical analysis at a 5% level of significance. The results revealed statistically significant increases in the surface wear of both instruments groups after the second use. The presence of irregularities was found on the surface topography of all the instruments, before and after use. Regardless of the evaluation stage, most of the defects were observed in the WaveOne instruments. The three-dimensional technique was suitable and effective for the accurate investigation of the same surfaces of the instruments in different periods of time.

Evaluation of inflammatory response of EDTA, EDTA-T, and citric acid in animal model.

INTRODUCTION: The biocompatibility of chelating agents and organic acids have been explained by a variety of methods, and suggestions for use have been based more on clinical observations and physicochemical properties than on biological aspects. The present study aimed to evaluate the inflammatory response of 17% EDTA, 17% EDTA-T, and 10% citric acid in bony defect created in rat jaws. METHODS: Mandibular through and through critical size defects were created bilaterally in 60 rats. Fibrinol (Baldacchi SA, São Paulo, Brazil), a cube-shaped compound of absorbable bovine fibrin foam and sodium chloride, was used as a carrier of the substances. One side had received Fibrinol (control), whereas the opposite side had received Fibrinol soaked with each substance on the 1st, on the 7th, on the 14th, and on the 28th day (n=5 for each day). Hemijaws were prepared for light microscopy, and samples were stained with hematoxylin and eosin. Digitized images were analyzed with a morphometric software (ImageJ; National Institute of Mental Health, Bethesda, MD). to obtain the number of inflammatory cells per area. Comparisons were performed by using the Kruskal-Wallis test (p=0.05). RESULTS: For all days, 10% citric acid and 17% EDTA-T showed, respectively, the lowest and highest number of inflammatory cells per area. All tested substances and controls showed the highest inflammatory cell response on the 14th day. CONCLUSION: Among the tested substances, 10% citric acid proved to be the less aggressive tested solution at 14 days. At 28 days, all solutions were similar, but EDTA-T kept showing the higher number of inflammatory cells.

A comparison of two reciprocating instruments using bending stress and cyclic fatigue tests

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 mm in length, were tested. The bending resistance was evaluated through the results of a cantilever-bending test conducted using a universal testing machine. Static and dynamic cyclic fatigue testing was conducted using a custom-made device. For the static and dynamic tests, a cast Ni-Cr-Mo-Ti alloy metal block with an artificial canal measuring 1.77 mm in diameter and 20.00 mm in total length was used. A scanning electron microscope was used to determine the type of fracture. Statistical analyses were performed on the results. The WaveOne instrument was less flexible than the Reciproc (p < 0.05). The Reciproc instrument showed better resistance in the static and dynamic cyclic fatigue tests (p < 0.05). The transverse cross-section and geometry of the instruments were important factors in their resistance to bending and cyclic fracture. Both of the instruments showed ductile-type fracture characteristics. It can be concluded that the Reciproc 25-08 instrument was more resistant to static and dynamic cyclic fatigue than the WaveOne 25-08 instrument, while the WaveOne 25-08 instrument was less flexible. Bending and resistance to cyclic fracture were influenced by the instruments’ geometries and transverse cross-sections. Both of the instruments showed ductile-type fracture characteristics.