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.Keywords: Citric Acid; Dentinal Tubule; Ethylenediaminetetraacetic Acid; Scanning Electron Microscopy; Surface Morpholog

Comparative sem evaluation of three solvents used in endodontic retreatment: an ex vivo study

This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>;0.05). However, the control group had fewer dentinal tubules free of filling material (

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.  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

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

Comparative evaluation of reciproc® and waveone® when submitted to bending stress and static and dynamic cyclic fatigue tests

O objetivo deste estudo foi de avaliar comparativamente a resistência a flexão em 45°,a fadiga cíclica estática e dinâmica e o tipo de fratura nos instrumentos WaveOne® (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 e Reciproc® (VDW, Munich, Germany) 25-08. Uma amostra, de 60 instrumentos de níquel-titânio (NiTi) (30 Reciproc® and 30 WaveOne®), de 25 mm de comprimento e pertencentes a 3 diferentes lotes, foi testada. A resistência a flexão foi avaliada usando um teste de flexão em cantilever em uma máquina de teste universal. Os testes de fadiga estática e dinâmica foram realizados usando-se uma máquina especificamente projetada. Um canal artificial medindo 1,77 mm de diâmetro, comprimento total de 20,00mm e um arco com raio de curvatura de 6,0 mm foi confeccionado em um bloco metálico fundido em liga Ni-Cr-Mo-Ti. Um microscópio eletrônico de varredura foi usado para analisar o tipo de fratura. Análises estatísticas foram realizadas com os valores obtidos. Os instrumentos WaveOne® apresentaram maior resistência à flexão do que o Reciproc® (p < 0.05). Os instrumentos Reciproc® apresentaram melhor resistência nos testes de fratura cíclica estática e dinâmica (p < 0.05). Pode- se concluir que o instrumento Reciproc 25-08 possui melhor resistência à fadiga cíclica estática e dinâmica do que o WaveOne® 25-08, enquanto que o WaveOne® 25-08 é mais resistente ã flexão. Ambos instrumentos mostraram características de fratura tipo dúctil.The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the type of fracture for WaveOne® (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc® (VDW, Munich, Germany) 25-08. A sample of 60 nickel-titanium (NiTi) instruments (30 Reciproc® and 30 WaveOne®), 25 mm in length and from 3 different lots, was tested. The bending resistance was evaluated using the cantilever-bending test with a universal testing machine. Static and dynamic cyclic fatigue tests were performed using a custom-made device. An artificial channel with 1.77 mm in diameter , 20.00 mm in total length and arcs on the tips with a curvature radius of 6.0 mm was molded in a Ni-Cr-Mo-Ti alloy cast metal block . A scanning electron microscope was used to analyze the type of fracture. Statistical analyses were performed on the obtained values. The WaveOne® instrument had greater bending resistance than the Reciproc® (p < 0.05). The Reciproc® had better resistance in the static and dynamic cyclic fatigue tests (p < 0.05). It can be concluded that the Reciproc® 25-08 instrument has better resistance to static and dynamic cyclic fatigue than the WaveOne® 25-08, while the WaveOne® 25-08 is more resistant to bending. Both instruments showed ductile-type fracture characteristics.38f

Comparative Study the Physical Properties of Flow, Solubility and Disintegration of Some Root Canal Sealers

Objective: The aim of this study was to evaluate comparatively the physical properties of solubility, disintegration and flow of some root canal sealers: SEALAPEX™, PULP CANAL SEALER™, TUBLISEAL™, AH PLUS™, AH 26™, TOP SEAL™, SEALER PLUS™, SEALER 26™ and ENDOFILL™. Method: Methodology used was according ISO 6786 which test the physicochemical properties using five proof specimens for each test. Results: In terms of solubility, the root canal sealers analyzed have been classified in the following decreasing order: ENDOFILL™, SEALAPEX™, PULP CANAL SEALER™, AH 26™, TUBLISEAL™, SEALER PLUS™, AH PLUS™, TOP SEAL™ and SEALER 26™, where a statistically significant difference was found at a 1% level. Between TOP SEAL™ and SEALER™ 26 root canal sealers there was no statistically significant difference. None of the sealers above have shown disintegration. Regarding flow, the root canal sealers in the study have been classified in the following decreasing order: TUBLISEAL™ root canal sealer, followed by ENDOFILL™, SEALAPEX™, PULP CANAL SEALER™, AH PLUS™, TOP SEAL™, AH 26™, SEALER 26™ and SEALER PLUS™, where a statistically significant difference was found at a 1% level. Conclusion: The solubility, only the SEALAPEX™ and ENDOFILL™ have shown a limit above determined by ISO 6786

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&#8217; geometries and transverse cross-sections. Both of the instruments showed ductile-type fracture characteristics

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