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Article in English | WPRIM | ID: wpr-929140


Various engine-driven NiTi endodontic files have been indispensable and efficient tools in cleaning and shaping of root canals for practitioners. In this review, we introduce the relative terms and conceptions of NiTi file, including crystal phase composition, the design of the cutting part, types of separation. This review also analysis the main improvement and evolution of different generations of engine-driven nickel-titanium instruments in the past 20 years in the geometric design, manufacturing surface treatment such as electropolishing, thermal treatment, metallurgy. And the variety of motion modes of NiTi files to improve resistance to torsional failure were also discussed. Continuous advancements by the designers, provide better balance between shaping efficiency and resistance to of NiTi systems. In clinical practice an appropriate system should be selected based on the anatomy of the root canal, instrument characteristics, and operators' experience.

Dental Alloys/chemistry , Dental Instruments , Equipment Design , Nickel/chemistry , Root Canal Preparation , Titanium/chemistry
Rev. ABENO ; 21(1): 1236, dez. 2021. tab
Article in English | LILACS, BBO | ID: biblio-1370621


Many studies address the quality of root canal treatments, but few refer to endodontics usingrotatory techniques performed by noviceoperators. This study evaluatedthe performance of undergraduates in their first contact with rotary root canal instrumentation concerningthe findings of the final periapical radiograph, and thepostendodontic treatment pain.A longitudinal observational studywas performed on periapical radiographs of 491teethfrom 450 patientssubmitted toroot canal treatmentby undergraduate students from 2015 to 2018. The analysis of the length of root canal filling followed the criteria: (i) acceptable, ifperiapical radiograph presentsroot filling ending 0 -1 mm short of radiographic apex; (ii) over, if periapical radiograph presentsroot filling ending beyond the radiographic apex; and (iii) under, ifperiapical radiograph presentsroot filling ending > 1 mm short of radiographic apex. Evaluation of postendodontic treatment painwas categorized into either absence or presenceof pain. Adequate length root canal filling was observed in 65.9% of the cases (324 teeth). Periapical lesions presenceand dimensions did not interfere to the obturation quality.Statistical relation was found between the pulp condition and postendodontic treatment pain. Thepresence of pain was observed in 4.7% of the vital teeth and 0.3% of non-vital teeth. The presence of periapical lesion did not influence postoperative pain.AdequatelengthrootcanalfillingwasobservedinmostcasesandNitTi rotary instrumentation hadapplicability in undergraduate programs, even with novice operators. Besides that, pulp condition had an effect on post endodontic pain (AU).

Muitos estudos abordam a qualidade dos tratamentos de canal radicular, mas poucos se referem à endodontia por meio de técnicas rotatórias realizada por operadores novatos. Este estudo avaliou o desempenho de graduandos no primeiro contato com a instrumentação endodôntica em relação aos achados da radiografia periapical final e à dor pós-tratamento endodôntico. Um estudo observacional longitudinal foi realizado em radiografias periapicais de 491 dentes de 450pacientes submetidos a tratamento endodôntico por estudantes de graduação no período de 2015 a 2018. A análise do comprimento da obturação de canais radiculares obedeceu aos critérios: (i) aceitável, se a radiografia periapical apresentasse término de obturação 0 -1 mm aquém do ápice radiográfico; (ii) acima, se a radiografia periapical apresentasse obturação que termina além do ápice radiográfico; e (iii) abaixo, se a radiografia periapicalapresentasse obturação, terminando > 1 mm aquém do ápice radiográfico. A avaliação da dor pós-operatória foi categorizada em ausência ou presença de dor. A obturação de canais radiculares de comprimento adequado foi observada em 65,9% dos casos (324 dentes). A presença e as dimensões das lesões periapicais não interferiram na qualidade da obturação. Foi encontrada relação estatística entre a condição pulpar e a dor pós-tratamento endodôntico. Presença de dor foi observada em 4,7% dos dentes vitais e 0,3% dos não vitais. A presença de lesão periapical não influenciou na dor pós-operatória. O comprimento de trabalho adequado foi observado na maioria dos casos e a instrumentação rotatória NitTi teve aplicabilidade em programas de graduação, mesmo com operadores iniciantes. Além disso, a condição pulpar afetou a dor pós-operatória (AU).

Humans , Male , Female , Pain, Postoperative/surgery , Root Canal Obturation/instrumentation , Students, Dental , Radiography, Dental/instrumentation , Root Canal Preparation/instrumentation , Titanium/chemistry , Chi-Square Distribution , Dental Records , Data Interpretation, Statistical , Longitudinal Studies , Tooth Apex/surgery , Dental Instruments , Endodontics/instrumentation , Observational Study , Nickel/chemistry
Int. j. morphol ; 38(4): 909-913, Aug. 2020. tab, graf
Article in English | LILACS | ID: biblio-1124875


Porous titanium alloy scaffold was widely used in treating bone defect caused by traumatic injury and osteomyelitis, which was incapable of self-healing. The implantation of scaffold produced stress shielding thereby forming osteolysis. The objective of this study was to analysis trabecular morphological features of osseointegrated bone. 14 New Zealand rabbits were divided into two groups, surgery group and healthy control group. 7 rabbits in surgery group were selected to perform 3D printed porous titanium alloy scaffold implantation surgery with preload at the defect of femoral condyle for osseointegration. The other 7 rabbits in control group were feed free. After 90 days healing, femoral condyles were extracted to perform micro-CT scanning with hydroxyapatite calibration phantom. Mean bone mineral density (BMD), bone volume fraction (BV/TV), BS/TV (bone surface area ratio), Tb.Th (thickness of trabeculae), Tb.N (number of trabeculae), Tb.Sp (trabecular separation) and DA (degree of anisotropy) were calculated from micro-CT images. The results revealed that osseointegration inside and at the surface of scaffolds worked well from grey values of micro-CT images. After 12 weeks healing, mean bone mineral densities (BMD) in surgery group and healthy control group were calculated as 800±20mg/cm3 and 980±90mg/cm3, respectively. This revealed that the strength of trabeculae in surgery group might lower than that in the healthy group. Trabecular morphological parameters test showed that trabecular morphological parameters at the surface of scaffolds in the surgery group deteriorated significantly. It was found from micro-CT images that ingrowth bone was filled with pores of scaffold. Overall, the effect of osseointegration was promoted through the change of mechanical micro-environment in the scaffold region. Overall, preload could improve osseointegration effect in the long-term after surgery. However, the trabecular morphology in the surgery group was deteriorated, which might bring secondary fracture risk again.

La malla de aleación de titanio poroso se usó ampliamente en el tratamiento de defectos óseos causados por lesiones traumáticas y osteomielitis. El implante de la malla generó una protección contra el estrés, formando así osteolisis. El objetivo de este estudio fue analizar las características morfológicas trabeculares del hueso osteointegrado. Se dividieron 14 conejos (Neozelandeses) en dos grupos, grupo cirugía y grupo control saludable. Se seleccionaron 7 conejos en el grupo de cirugía para realizar una implantación de mallas de aleación de titanio poroso, impresas en 3D con precarga en el defecto del cóndilo femoral para la osteointegración. Los 7 conejos restantes del grupo control se mantuvieron sin alimentación. Después de 90 días de curación, se extrajeron los cóndilos femorales para realizar una exploración por micro-CT con un espectro de calibración de hidroxiapatita. Se calcularon a partir de imágenes de micro-CTDensidad mineral ósea media (DMO), fracción de volumen óseo (BV / TV), BS / TV (relación de área de superficie ósea), Tb.Th (espesor de trabéculas), Tb.N (número de trabéculas), Tb.Sp (trabecular separación) y DA (grado de anisotropía). Los resultados revelaron que la osteointegración dentro y en la superficie de los andamios funcionó bien a partir de los valores grises de las imágenes de micro-CT. Después de 12 semanas de curación, las densidades medias de minerales óseos (DMO) en el grupo cirugía y en el grupo control sano se calcularon como 800 ± 20 mg/cm3 y 980 ± 90 mg/cm3, respectivamente. Esto reveló que la fuerza de las trabéculas en el grupo de cirugía podría ser menor que la del grupo sano. La prueba de parámetros morfológicos trabeculares mostró que en el grupo de cirugía, la superficie de las mallas, se deterioraron significativamente. Se descubrió a partir de imágenes de microCT que el hueso en crecimiento estaba lleno de poros de andamio. En general, el efecto de la osteointegración se promovió mediante el cambio del microambiente mecánico en la región de la malla. En general, la precarga podría mejorar el efecto de osteointegración a largo plazo después de la cirugía. Sin embargo, la morfología trabecular en el grupo de cirugía se deterioró, lo que podría traer un nuevo riesgo de fractura secundaria.

Animals , Rabbits , Bone Diseases/surgery , Osseointegration/physiology , Tissue Scaffolds/chemistry , Printing, Three-Dimensional , Prostheses and Implants , Titanium/chemistry , Porosity , Alloys , X-Ray Microtomography , Femur/surgery
J. appl. oral sci ; 28: e20190156, 2020. graf
Article in English | LILACS, BBO | ID: biblio-1090765


Abstract Objective The present study aimed to investigate the participation of focal adhesion kinases (FAK) in interactions between osteoblastic cells and titanium (Ti) surfaces with three different topographies, namely, untreated (US), microstructured (MS), and nanostructured (NS). Methodology Osteoblasts harvested from the calvarial bones of 3-day-old rats were cultured on US, MS and NS discs in the presence of PF-573228 (FAK inhibitor) to evaluate osteoblastic differentiation. After 24 h, we evaluated osteoblast morphology and vinculin expression, and on day 10, the following parameters: gene expression of osteoblastic markers and integrin signaling components, FAK protein expression and alkaline phosphatase (ALP) activity. A smooth surface, porosities at the microscale level, and nanocavities were observed in US, MS, and NS, respectively. Results FAK inhibition decreased the number of filopodia in cells grown on US and MS compared with that in NS. FAK inhibition decreased the gene expression of Alp, bone sialoprotein, osteocalcin, and ALP activity in cells grown on all evaluated surfaces. FAK inhibition did not affect the gene expression of Fak, integrin alpha 1 ( Itga1 ) and integrin beta 1 ( Itgb1 ) in cells grown on MS, increased the gene expression of Fak in cells grown on NS, and increased the gene expression of Itga1 and Itgb1 in cells grown on US and NS. Moreover, FAK protein expression decreased in cells cultured on US but increased in cells cultured on MS and NS after FAK inhibition; no difference in the expression of vinculin was observed among cells grown on all surfaces. Conclusions Our data demonstrate the relevance of FAK in the interactions between osteoblastic cells and Ti surfaces regardless of surface topography. Nanotopography positively regulated FAK expression and integrin signaling pathway components during osteoblast differentiation. In this context, the development of Ti surfaces with the ability to upregulate FAK activity could positively impact the process of implant osseointegration.

Animals , Osteoblasts/drug effects , Sulfones/pharmacology , Titanium/chemistry , Quinolones/pharmacology , Focal Adhesion Protein-Tyrosine Kinases/antagonists & inhibitors , Osteoblasts/physiology , Sulfones/chemistry , Surface Properties , Microscopy, Electron, Scanning , Signal Transduction , Gene Expression , Integrins/analysis , Cell Differentiation/drug effects , Cells, Cultured , Osseointegration/drug effects , Rats, Wistar , Quinolones/chemistry , Cell Proliferation/drug effects , Focal Adhesion Protein-Tyrosine Kinases/analysis , Focal Adhesion Protein-Tyrosine Kinases/chemistry , Real-Time Polymerase Chain Reaction
Int. j. odontostomatol. (Print) ; 13(1): 51-57, mar. 2019. tab, graf
Article in Spanish | LILACS | ID: biblio-990064


RESUMEN: El barro dentinario producido durante tratamiento endodóntico puede ser extruido hacia el tejido periradicular junto con el irrigante, produciendo inflamación y dolor postoperatorio. Comparar la cantidad de extrusión apical de barro dentinario e irrigante, producido durante la preparación químico-mecánica, por dos sistemas de instrumentación Rotatoria (Mtwo), y Reciprocante (Reciproc), complementado con irrigación pasiva o activa (Endoactivator). Cuarenta y ocho premolares (48) inferiores, fueron aleatoriamente distribuidos en cuatro grupos de estudio (n=12 dientes), (1) Rotatorio-pasiva, (2) Reciprocante-pasiva, (3) Rotatorio-activa y (4) Reciprocante-activa. Los conductos radiculares fueron instrumentados de acuerdo a las instrucciones del fabricante, e irrigados con hipoclorito de sodio al 5 %. El barro dentinario e irrigante extruido, fueron recolectados en tubos Eppendorf previamente pesados. Se calcularon los valores de extrusión de barro dentinario e irrigante para cada grupo. Los datos fueron analizados con el análisis de varianza ANOVA. En todos los grupos se produjo extrusión apical. No se encontraron diferencias estadísticamente significativas en la extrusión apical de barro dentinario, entre los grupos estudiados (P = 0,068), sin embargo, al analizar la extrusión de irrigantes, se evidenció diferencia estadísticamente significativa entre los grupos 1 y 4 (P< 0,05), entre los demás grupos no se observaron diferencias estadísticamente significativas. (P > 0,05). Bajo las condiciones de este estudio, los sistemas rotarios y reciprocante, extruyen sólido y líquido, siendo el sistema reciprocante el que produce mayor extrusión de líquido, tanto con irrigación activa como pasiva.

ABSTRACT: The smear layer produced during endodontic treatment can be extruded into the periradicular tissue together with the irrigant, producing inflammation and postoperative pain. The purpose of this in vitro study was to compare the amount of apical extrusion, produced during the endodontic preparations with two rotary instrumentation systems using passive and active irrigation. Forty-eight (48) mandibular premolars were randomly assigned to 4 groups (n = 12 teeth), (1) Rotatory - passive, (2) Reciprocating passive, (3) Rotatory-active, (4) Reciprocating- active. The root canals were instrumented according to the manufacturer's instructions and irrigated with 5 % sodium hypochlorite. Extruded debris and irrigant were collected in previously weighed Eppendorf tubes. The extrusion values were calculated for each group. The data were analyzed with the ANOVA analysis of variance. Results: Apical extrusion was produced in all groups. No statistically significant differences were found in the apical extrusion of smear layer, between the groups studied (P = 0.068), however, when analyzing the extrusion of irrigants, a statistically significant difference was evidenced between groups 1 and 4 (P <0.05). , among the other groups no statistically significant differences were observed. (P> 0.05). Under the conditions of this study, the reciprocating and rotary systems, extrude solid and liquid, being the reciprocating system the one that produces more extrusion of liquid, with both active and passive irrigation.

Humans , Root Canal Irrigants , Smear Layer , Therapeutic Irrigation/instrumentation , Titanium/chemistry , Bicuspid , In Vitro Techniques , Analysis of Variance , Nickel/chemistry
Braz. oral res. (Online) ; 33: e079, 2019. graf
Article in English | LILACS | ID: biblio-1019604


Abstract Cell therapy associated with guided bone regeneration (GBR) can be used to treat bone defects under challenging conditions such as osteoporosis. This study aimed to evaluate the effect of mesenchymal stem cells (MSCs) in combination with a poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT) membrane on bone repair in osteoporotic rats. Osteoporosis was induced in female rats by bilateral removal of the ovaries (OVX) or sham surgery (SHAM), and the osteoporotic condition was characterized after 5 months by microtomographic and morphometric analyses. Calvarial defects were created in osteoporotic rats that immediately received the PVDF-TrFE/BT membrane. After 2 weeks, bone marrow-derived MSCs from healthy rats, characterized by the expression of surface markers using flow cytometry, or phosphate-buffered saline (PBS) (Control) were injected into the defects and bone formation was evaluated 4 weeks post-injection by microtomographic, morphometric, and histological analyses. A reduction in the amount of bone tissue in the femurs of OVX compared with SHAM rats confirmed the osteoporotic condition of the experimental model. More bone formation was observed when the defects were injected with MSCs compared to that with PBS. The modification that we are proposing in this study for the classical GBR approach where cells are locally injected after a membrane implantation may be a promising therapeutic strategy to increase bone formation under osteoporotic condition.

Animals , Female , Polyvinyls/pharmacology , Titanium/pharmacology , Barium Compounds/pharmacology , Guided Tissue Regeneration/methods , Mesenchymal Stem Cells/physiology , Osteogenesis/drug effects , Osteoporosis/physiopathology , Osteoporosis/therapy , Polyvinyls/chemistry , Time Factors , Titanium/chemistry , Bone Regeneration/drug effects , Bone Regeneration/physiology , Ovariectomy , Random Allocation , Bone Density , Reproducibility of Results , Treatment Outcome , Rats, Wistar , Barium Compounds/chemistry , Imaging, Three-Dimensional , Mesenchymal Stem Cells/chemistry , Flow Cytometry
Braz. oral res. (Online) ; 33: e016, 2019. tab, graf
Article in English | LILACS | ID: biblio-989478


Abstract To synthesize Nano eggshell-titanium-dioxide (EB@TiO2) biocomposite and to evaluate its effectiveness in occluding opened dentine tubules. EB@TiO2 was synthesized and characterized using X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). Sixteen simulated bovine dentine discs were prepared and randomly assigned into four groups according to the following treatment (n = 4): Group 1: No treatment; Group 2: eggshell powder; Group 3: EB@TiO2; Group 4: Sensodyne. These were then agitated in a solution of 1g powder and 40mL water for 3hours. Thereafter, each dentine discs from the respective groups were post-treated for 5 min with 2wt% citric acid to test their acid resistant characteristics. Scanning Electron Microscope (SEM) was used to observe the effectiveness of occluded dentine pre-and post-treatment. The cytotoxicity of the synthesized EB@TiO2 was tested using NIH 3T3 assay. ANOVA was used to evaluate the mean values of the occluded area ratio and the data of MTS assay. This was followed by a multi-comparison test with Bonferroni correction (α = .05). The XRD confirmed that EB@TiO2 was successfully modified through ball-milling. The TEM revealed the presence of both spherical and irregular particle shape powders. The SEM result showed that EB@TiO2 could effectively occlude open dentine tubules. Equally, the result demonstrated that EB@TiO2 exhibited the highest acid resistant stability post-treatment. NIH 3T3 assay identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100µg/ml. This study suggests that the application of EB@TiO2 effectively occluded dentine tubules and the occlusion showed a high acid resistant stability.

Animals , Cattle , Mice , Phosphates/pharmacology , Titanium/chemistry , Dentin Permeability/drug effects , Dentin Sensitivity/therapy , Egg Shell/chemistry , Nanocomposites/chemistry , Dentin Desensitizing Agents/pharmacology , Fluorides/pharmacology , Nitrates/pharmacology , Titanium/analysis , Titanium/pharmacology , Tooth Remineralization , Microscopy, Electron, Scanning , NIH 3T3 Cells , Drug Combinations , Egg Shell/ultrastructure , Nanocomposites/analysis , Nanocomposites/therapeutic use
Braz. oral res. (Online) ; 33: e028, 2019. tab, graf
Article in English | LILACS | ID: biblio-1001600


Abstract: This study aimed to assess the cyclic fatigue resistance of Genius and EdgeFile X1 reciprocating instruments compared with WaveOne Gold Primary. Twenty Genius (Ultradent) 25.04, 20 Genius 30.04, 20 EdgeFile X1 (EdgeEndo) and 20 WaveOne Gold Primary (Dentsply Maillefer) instruments were included in this study and tested in a static cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated in reciprocation mode until fracture occurred. The number of cycles to failure (NCF) was calculated and time to fracture (TF) was recorded in seconds using a digital chronometer. The mean and standard deviations of NCF and TF were calculated for each reciprocating system and the data were subjected to Kruskal-Wallis one-way analysis of variance and to Dunn's test (p < .05) using SigmaPlot software (Systat software, CA, USA). The fractured surfaces of five instruments from each brand were randomly examined and microphotographed by a low-vacuum environmental scanning electron microscopy - SEM (Tabletop Microscope TM3030, Hitachi, Japan) to confirm the cyclic fatigue fracture. EdgeFile exhibited the highest cyclic fatigue resistance, followed by both Genius files (p < .05). Within the limitations of this in vitro study, EdgeFile X1 instruments had significantly higher cyclic fatigue resistance than did Genius and WaveOne Gold Primary instruments. The cyclic fatigue resistance of both Genius files was higher than that of WaveOne Gold Primary.

Titanium/chemistry , Root Canal Preparation/instrumentation , Dental Instruments/standards , Nickel/chemistry , Reference Values , Stress, Mechanical , Surface Properties , Time Factors , Materials Testing , Microscopy, Electron, Scanning , Statistics, Nonparametric , Equipment Failure Analysis , Equipment Design
Braz. oral res. (Online) ; 33(supl.1): e065, 2019. tab, graf
Article in English | LILACS | ID: biblio-1039317


Abstract Additive manufacturing (AM) is an emerging process for biomaterials and medical devices. Direct Laser Metal Sintering (DLMS) is an AM technique used to fabricate Ti-6Al-4V implant materials with enhanced surface-related properties compared with wrought samples; thus, this technique could influence microbial adsorption and colonization. Therefore, this in vitro study was conducted to evaluate the impact of different implant production processes on microbial adhesion of periodontal pathogens. Titanium discs produced using two different processes—conventional and AM—were divided into three groups: conventional titanium discs with machined surface (G1), AM titanium discs with chemical treatment (G2) and AM titanium discs without chemical treatment (G3). Subgingival biofilm composed of 32 species was formed on the titanium discs, and positioned vertically in 96-well plates, for 7 days. The proportions of microbial complexes and the microbial profiles were analyzed using a DNA-DNA hybridization technique, and data were evaluated using Kruskal-Wallis and Dunnett tests (p < 0.05). Lower proportions of the red complex species were observed in the biofilm formed in G2 compared with that in G1 (p < 0.05). Moreover, the proportions of the microbial complexes were similar between G2 and G3 (p > 0.05). Compared with G1, G2 showed reduced levels of Porphyromonas gingvalis , Actinomyces gerencseriae, and Streptococcus intermedius , and increased levels of Parvimonas micra , Actinomyces odontolyticus, and Eikenella corrodens (p < 0.05). The microbial profile of G3 did not differ from G1 and G2 (p > 0.05). The results of this in vitro study showed that titanium discs produced via AM could alter the microbial profile of the biofilm formed around them. Further clinical studies should be conducted to confirm these findings.

Titanium/pharmacology , Titanium/chemistry , Biofilms/growth & development , Reference Values , Surface Properties , Time Factors , Bacteria/drug effects , Microscopy, Electron, Scanning , DNA Probes , Reproducibility of Results , Analysis of Variance , Statistics, Nonparametric , Microscopy, Atomic Force , Biofilms/drug effects , Photoelectron Spectroscopy
Dent. press endod ; 8(1): 23-28, Apr-Jun. 2018. ilus, tab
Article in Portuguese | LILACS, BBO | ID: biblio-883676


Objetivo: esse estudo comparou a flexibilidade de instrumentos de níquel-titânio rotatórios com diferentes conicidades, em diferentes diâmetros da haste helicoidal cônica (D3 e D6). Métodos: trinta instrumentos RaCe (FKG, La Chaux-de Fonds, Suíça), #40 (D0 = 40), com 25 mm de comprimento, foram divididos em três grupos (n = 10), de acordo com sua conicidade. No teste de flexão em cantiléver (45 graus), foram realizadas duas avaliações, com cargas aplicadas, em D3 e D6, para cada grupo. Resultados: a comparação das cargas aplicadas em D3 e D6 nos instrumentos RaCe com diferentes conicidades mostrou valores de carga máxima significativamente diferentes para flexionar os instrumentos: D3 < D6, com a flexibilidade em D3 maior do que em D6. A comparação das cargas aplicadas em D3 nos três grupos revelou diferenças significativas entre os grupos (p < 0,0001), enquanto o teste Student-Newman-Keuls (SNK) mostrou diferenças de flexibilidade entre os três grupos: 0,06 < 0,04 < 0,02mm/mm. O mesmo resultado foi encontrado na comparação da força aplicada em D6. Conclusões: a flexibilidade do instrumento aumenta com a redução da conicidade (p < 0,05) e diminui com o aumento no diâmetro do eixo helicoidal (p < 0,05).

Analysis of Variance , Dental Instruments/statistics & numerical data , Endodontics/instrumentation , Nickel/chemistry , Pliability , Titanium/chemistry
Braz. dent. j ; 29(2): 208-213, Mar.-Apr. 2018. tab, graf
Article in English | LILACS | ID: biblio-951538


Abstract The aim of the present study was to evaluate the cyclic fatigue of two anatomic finishing files: XP-Endo Finisher and XP-Clean. Roughness pattern and the micro-hardness of the files were also assessed. Instruments were subjected to cyclic fatigue resistance measuring the time to fracture in an artificial stainless-steel canal with a 60° angle and a 5-mm radius of curvature. The fracture surface of all fragments was examined with a scanning electron microscope. The roughness of the working parts was quantified by using a profilometer and the micro-hardness test was carried out using a Vickers hardness tester. Results were statistically analyzed using a student´s t-test at a significance level of P < 0.05. Weibull analysis was also performed. XP-Endo Finisher presented significantly longer cyclic fatigue life than XP-Clean instruments (P<0.05). XP-Endo Finisher was able to withstand 1000% more cycles to fracture when compared to XP-Clean instruments. SEM visual inspection of the fracture surfaces revealed fractographic characteristics of ductile fracture in all tested instruments; wide-ranging forms of dimples were identified and no plastic deformation in the helical shaft of the fractured instruments was observed. When mean life was compared XP-Endo Finisher lasted longer than XP-Clean with a probability of 99.9%. XP-Endo Finisher instruments also exhibited significantly lower roughness than XP-Clean instruments (P<0.05). No differences in the micro-hardness was observed between the files (P>0.05). It can be concluded that XP-Endo Finisher instruments showed improved performance when compared with XP-Clean instruments, demonstrating higher cyclic fatigue resistance and lower roughness.

Resumo O objetivo do presente estudo foi avaliar a fadiga cíclica de dois instrumentos finalizadores anatômicos: XP-Endo Finisher e XP-Clean. O padrão de rugosidade e a micro dureza dos instrumentos também foram avaliados. Os instrumentos foram submetidos à resistência à fadiga cíclica, medindo o tempo de fratura em um canal artificial de aço inoxidável com um ângulo de 60 ° e um raio de curvatura de 5 mm. A superfície de fratura de todos os fragmentos foi examinada com um microscópio eletrônico de varredura. A rugosidade dos instrumentos foi quantificada usando um perfilômetro e o teste de micro dureza foi realizado usando um testador de dureza Vickers. Os resultados foram analisados ​​estatisticamente usando o teste t de student em um nível de significância de p<0,05. A análise Weibull também foi realizada. XP-Endo Finisher apresentou vida de fadiga cíclica significativamente mais longa do que os instrumentos XP-Clean (p<0,05). XP-Endo Finisher foi capaz de suportar 1000% mais ciclos para fratura quando comparado aos instrumentos XP-Clean. A inspeção visual em microscópio eletrônico de varredura das superfícies de fratura revelou características fractográficas da fratura dúctil em todos os instrumentos testados. Não foi observada deformação plástica no eixo helicoidal dos instrumentos fraturados. Quando o tempo para a fratura foi comparado entre os instrumentos, o XP-Endo Finisher durou mais do que o XP-Clean com uma probabilidade de 99,9%. Os instrumentos XP-Endo Finisher também exibiram uma rugosidade significativamente menor do que os instrumentos XP-Clean (p<0,05). Não foram observadas diferenças na micro dureza entre os arquivos (p>0,05). Pode-se concluir que os instrumentos XP-Endo Finisher apresentaram desempenho melhorado em comparação com os instrumentos XP-Clean, demonstrando maior resistência à fadiga cíclica e menor rugosidade.

Materials Testing , Root Canal Preparation/instrumentation , Dental Instruments , Stainless Steel/chemistry , Surface Properties , Titanium/chemistry , Microscopy, Electron, Scanning , Alloys , Hardness Tests , Nickel/chemistry
Braz. dent. j ; 29(1): 54-59, Jan.-Feb. 2018. tab, graf
Article in English | LILACS | ID: biblio-888720


Abstract The aim of this study was to assess the amount of apically extruded debris during filling removal with WaveOne Gold (WOG), ProTaper Universal Retreatment (PTR), D-RaCe Retreatment (DRR) or hand files (HF), to compare the working time during filling removal, and to describe failures of NiTi instruments. Forty mesiobuccal roots of maxillary first molars were prepared with WOG Primary, obturated and divided into 4 groups (n=10), according to the instruments used: WOG, PTR, DRR or HF. Distilled water was used as irrigant and the extruded debris were collected in Eppendorf tubes and dried. The amount of extruded debris was determined by subtracting the final from the initial weight. The time of filling removal for each canal was recorded and the instruments used were analyzed pre and post-operatively by SEM. Kruskal-Wallis and Dunn's test analyzed extruded debris data and ANOVA, followed by Tukey's test, compared the working time data (a=0.05). Instrument deformation and fracture were described. WOG produced significantly less debris compared with HF and DRR (p<0.05), and similar to PTR (p>0.05). HF, PTR and DRR showed no significant difference (p>0.05). Working time in HF group was significantly higher than others (p<0.05). SEM analyses showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. All instruments tested caused debris extrusion. WOG was associated with less extrusion than DRR and HF. Filling removal with HF was slower than with the other instruments. All NiTi systems presented fracture and deformation.

Resumo O objetivo deste estudo foi avaliar a extrusão apical de debris durante a desobturação com WaveOne Gold (WOG), ProTaper Universal Retratamento (PTR), D-RaCe (DRR) ou limas manuais (HF), comparar o tempo de trabalho durante a desobturação, e descrever as falhas dos instrumentos de NiTi. Quarenta canais de raízes mésio-vestibulares de primeiros molars superiores foram preparados com WOG Primary, obturados e divididos em 4 grupos (n = 10), de acordo com os instrumentos a serem utilizados: WOG, PTR, DRR ou HF. Água destilada foi utilizada como irrigante, e os debris extruídos foram coletados em tubos Eppendorf e secos. A quantidade de debris extruídos foi determinada subtraindo-se o peso inicial do peso final. O tempo de cada desobturação foi anotado e os instrumentos utilizados foram analisados no pré e pós-operatório em MEV. Os testes Kruskal-Wallis e Dunn foram utilizados para analisar os dados da extrusão de debris, e os testes ANOVA e Tukey para comparar os dados do tempo de trabalho (a=0.05). As deformações e fraturas dos instrumentos foram descritas. O grupo WOG produziu significativamente menos debris quando comparado aos grupos HF e DRR (p<0.05), e foi similar ao grupo PTR (p>0.05). Os grupos HF, PTR e DRR não apresentaram diferença estatisticamente significante (p>0.05). O tempo de trabalho no grupo HF foi significativamente maior do que nos outros grupos (p<0.05). A análise em MEV mostrou que, dos 18 instrumentos avaliados, 3 fraturaram e em 10 foi observado deformação. Todos os sistemas testados causaram extrusão apical de debris. WOG foi associado com menor extrusão do que DRR e HF. A desobturação com HF foi mais lenta do que com os demais instrumentos. Todos os sistemas de NITI apresentaram fratura e deformação.

Humans , Nickel/chemistry , Root Canal Preparation/instrumentation , Titanium/chemistry , Tooth Apex , Therapeutic Irrigation
Acta cir. bras ; 33(1): 14-21, Jan. 2018. tab, graf
Article in English | LILACS | ID: biblio-886252


Abstract Purpose: To compare the influence of two metallic implants in the diagnosis of periprosthetic infection using 99m technetium-labeled ceftizoxime. Methods: Twenty rats were randomly divided into four groups, which received sterile and contaminated titanium and stainless steel implants. After 3 weeks, scintilographic images were obtained using a gamma chamber. Radioactivity counts were obtained for the region of interest (ROI) on the operated and non-operated paws. Results: Groups A, B, and C showed homogenous distribution of the radiopharmaceutical. Hyper uptake was observed in the operated paw from group D. The ROI target count was higher in the two groups with stainless steel implants. Among the control groups, the count was higher in the stainless steel group. Furthermore, among the contaminated groups, the uptake was higher in the stainless steel group, with a significant difference. The target: non-target ratio was significantly lower in the control and contaminated groups with both titanium and stainless steel, but the comparison between control groups and contaminated groups was only significant in the former. The cpm/g observed after a decay of 48h showed statistically significant differences between groups. Conclusion: Different biomaterials used in implants have an influence on the results of scintigraphy with 99mTc-CFT.

Animals , Stainless Steel/radiation effects , Titanium/radiation effects , Ceftizoxime/analogs & derivatives , Organotechnetium Compounds , Prosthesis-Related Infections/diagnostic imaging , Radiopharmaceuticals , Radioactivity , Reference Values , Stainless Steel/chemistry , Time Factors , Titanium/chemistry , Biocompatible Materials/chemistry , Random Allocation , Radionuclide Imaging , Reproducibility of Results , Prosthesis-Related Infections/microbiology , Rats, Wistar
J. appl. oral sci ; 26: e20180144, 2018. graf
Article in English | LILACS, BBO | ID: biblio-954493


Abstract Objective The aim of this study was to evaluate the influence of torsional preloading on the cyclic flexural fatigue resistance of thermally treated NiTi instruments. Material and Methods Ten new instruments New Hyflex CM (HF 30.06; Coltene/Whaladent Inc.), Typhoon CM (TYP 30.06; Clinician's Choice Dental Products) and Vortex Blue (VB 30.06; Dentsply Tulsa Dental) were chosen, based on geometry and specific characteristics of the manufacturing process. The new instruments of each system were tested in a bench device to determine their fatigue resistance through mean value of number of cycles to failure (Nf) (Control Group - CG). Another group of 10 new HF, TYP and VB instruments were submitted to 20 cycles of torsional straining between 0° and 180° (Experimental Group - EG) and then submitted to fatigue until rupture under the same conditions of the CG. Tested instruments were examined by scanning electron microscopy (SEM). Data were analyzed using one-way analysis of variance and post hoc Tukey's test (α=.05). Results Higher fatigue resistance was accomplished by HF instruments, followed by VB and TYP (p<0.05). During the torsional preloading, the lowest mean torque value was observed for TYP instruments (p<0.05). The torsional preload caused a significant reduction in the Nf values (p<0.05) of about 20%, 39% and 45% for instruments HF, VB and TYP, respectively. Longitudinal cracks, generated during the torsional preloading, were present in VB files, but were not observed in the CM instruments (HF and TYP). Conclusions In conclusion, the flexural fatigue resistance of thermally treated instruments is diminished after cyclic torsional loading.

Titanium/chemistry , Dental Instruments/standards , Equipment Design/methods , Equipment Failure , Torsion, Mechanical , Nickel/chemistry , Reference Values , Rotation , Stress, Mechanical , Surface Properties , Temperature , Time Factors , Materials Testing , Microscopy, Electron, Scanning , Reproducibility of Results , Pliability , Root Canal Preparation/instrumentation
J. appl. oral sci ; 26: e20170220, 2018. tab, graf
Article in English | LILACS, BBO | ID: biblio-893730


Abstract Coated archwires and ceramic brackets have been developed to improve facial esthetics during orthodontic treatment. However, their mechanical behavior has been shown to be different from metallic archwires and brackets. Therefore, the aim of this study was to compare the deflection forces in coated nickel-titanium (NiTi) and esthetic archwires combined with ceramic brackets. Material and Methods Non-coated NiTi (NC), rhodium coated NiTi (RC), teflon coated NiTi (TC), epoxy coated NiTi (EC), fiber-reinforced polymer (FRP), and the three different conventional brackets metal-insert polycrystalline ceramic (MI-PC), polycrystalline ceramic (PC) and monocrystalline ceramic (MC) were used. The specimens were set up on a clinical simulation device and evaluated in a Universal Testing Machine (Instron). An acrylic device, representative of the right maxillary central incisor was buccolingually activated and the unloading forces generated were recorded at 3, 2, 1 and 0.5 mm. The speed of the testing machine was 2 mm/min. ANOVA and Tukey tests were used to compare the different archwires and brackets. Results The brackets presented the following decreasing force ranking: monocrystalline, polycrystalline and polycrystalline metal-insert. The decreasing force ranking of the archwires was: rhodium coated NiTi (RC), non-coated NiTi (NC), teflon coated NiTi (TC), epoxy coated NiTi (EC) and fiber-reinforced polymer (FRP). At 3 mm of unloading the FRP archwire had a plastic deformation and produced an extremely low force in 2; 1 and 0.5 mm of unloading. Conclusion Combinations of the evaluated archwires and brackets will produce a force ranking proportional to the combination of their individual force rankings.

Orthodontic Wires , Titanium/chemistry , Ceramics/chemistry , Orthodontic Brackets , Orthodontic Appliance Design/methods , Coated Materials, Biocompatible/chemistry , Nickel/chemistry , Reference Values , Surface Properties , Materials Testing , Reproducibility of Results , Analysis of Variance , Friction , Statistics, Nonparametric , Esthetics, Dental , Mechanical Phenomena
J. appl. oral sci ; 26: e20160590, 2018. tab, graf
Article in English | LILACS, BBO | ID: biblio-893721


Abstract The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Material and Methods: Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). Results: For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was −15.7 to 3.5 μm for LMMs and −3.0 to 1.9 μm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 μm/-7.6 μm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was −1.3 to 2.3 μm. Conclusion: LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.

Replica Techniques/methods , Dental Prosthesis Design/methods , Computer-Aided Design , Dental Marginal Adaptation/standards , Models, Dental/standards , Microscopy/methods , Reference Standards , Reference Values , Titanium/chemistry , Observer Variation , Reproducibility of Results
J. appl. oral sci ; 26: e20170222, 2018. tab, graf
Article in English | LILACS, BBO | ID: biblio-893701


Abstract The effect of fluoride agents on the retention of orthodontic brackets to enamel under erosive challenge is little investigated. Objective: The aim of this study was to evaluate the effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) agents on the shear bond strength of brackets to enamel and on the enamel microhardness around brackets under erosive challenge. Methods: Brackets were bonded to bovine incisors. Five groups were formed according to fluoride application (n=10): TiF4 varnish, TiF4 solution, NaF varnish, NaF solution and control (without application). The specimens were submitted to erosive challenge (90 s cola drink/2h artificial saliva, 4x per day for 7 days). Solutions were applied before each erosive cycle and varnishes were applied once. Vickers Microhardness (VHN) was obtained before and after all cycles of erosion and the percentage of microhardness loss was calculated. Shear bond strength, adhesive remnant index and polarized light microscopy were conducted after erosion. The data were analyzed by ANOVA, Tukey, Kruskal-Wallis and Mann-Whitney U tests (α=0.05). Results: The %VHN had no statistically significant differences among the experimental groups. However, considering the comparisons of all groups with the control group, TiF4 varnish showed the highest protection from enamel demineralization (effect size of 2.94, while the effect size for the other groups was >2.4). The TiF4 varnish group had significantly higher shear bond strength compared to other groups. There was no difference among groups for adhesive remnant index. Polarized light microscopy showed higher demineralization depth for the control group. Conclusions: Application of NaF and TiF4 agents during mild erosive challenge minimized the enamel mineral loss around brackets, however only the experimental TiF4 varnish was able to prevent the reduction of shear bond strength of brackets to enamel.

Animals , Cattle , Sodium Fluoride/chemistry , Titanium/chemistry , Tooth Erosion/prevention & control , Cariostatic Agents/chemistry , Dental Bonding/methods , Orthodontic Brackets , Dental Enamel/drug effects , Fluorides/chemistry , Reference Values , Saliva, Artificial/chemistry , Surface Properties , Materials Testing , Reproducibility of Results , Analysis of Variance , Tooth Demineralization/prevention & control , Statistics, Nonparametric , Dental Enamel/chemistry , Shear Strength , Hardness Tests , Microscopy, Polarization
J. appl. oral sci ; 26: e20170215, 2018. tab, graf
Article in English | LILACS, BBO | ID: biblio-893700


Abstract Objective To evaluate the amount of apically extruded debris, percentage of foraminal enlargement and apical foramen (AF) deformation that occurred during root canal preparation with different reciprocation systems: Reciproc, WaveOne (M-Wire), and ProDesign R (Shape Memory Technology Wire) at two different working lengths (WLs): 0.0 and 1.0 mm beyond the AF. Material and methods The AF of 120 root canals in 60 mesial roots of mandibular molars were photographed with stereomicroscope and randomly assigned into four groups: manual, Reciproc (REC), WaveOne (WO), and ProDesign R (PDR); subsequently, they were further subdivided according to the WL (n=15). Teeth were instrumented, coupled to a dual collecting chamber, and then another photograph of each AF was captured. Extrusion was analysed by determining the weight of extruded debris. Each AF diameter was measured in pre- and post-instrumentation images to determine deformation, which was analysed, and afterwards the final format of AFs was classified (circular/oval/deformed). Results We found no significant differences when analysing each system at different WLs. When considering each WL, REC and WO showed highest extrusion values (P<.05); for AF enlargement, differences were observed only for WO, when it was used beyond the AF; differences were observed among M-Wire groups beyond the AF (P<.05). AF deformation was observed in all groups; PDR showed the lowest AF deformation values at both WLs; M-Wire groups showed 50% strain beyond the AF. Conclusion Authors concluded that beyond the apical limit, the alloy and taper are important aspects when considering extrusion and deformation.

Humans , Titanium/chemistry , Root Canal Preparation/adverse effects , Root Canal Preparation/instrumentation , Tooth Apex/chemistry , Nickel/chemistry , Reference Values , Random Allocation , Reproducibility of Results , Statistics, Nonparametric , Root Canal Preparation/methods , Tooth Apex/anatomy & histology , Dental Instruments/adverse effects , Equipment Design
Bauru; s.n; 2018. 144 p. ilus, tab.
Thesis in English | LILACS, BBO | ID: biblio-884453


The aim of this study was to evaluate canal transportation; centering ability; dentin thickness; change in volume, and time spent on shaping ability of maxillary molars prepared with mechanized NiTi file systems composed of a conventional NiTi alloy (Mtwo), a CM-Wire (Prodesign R and Hyflex CM) NiTi alloy, R-phase (Twisted File Adaptive) and an M-Wire (Reciproc) NiTi alloy]. With the purpose of understanding the role of new treated NiTi alloys in larger apical preparations, this type of preparation was evaluated in the mesiobuccal (MB) and distobuccal canal (DB) of maxillary molars, as well as, in the second mesiobuccal (MB2) canals in extracted maxillary first molars by means of micro-computed tomographic (micro- CT) imaging. For the second mesiobuccal canal (MB2) evaluation, thirty maxillary molars with Vertucci type IV canal configuration were selected and randomly divided into 3 groups (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. To assess the mesiobuccal and distobuccal canals, a total of 45 extracted maxillary molars were selected according to the following criteria: MB canals exhibiting curvatures according to the Weine classification in the 20-30 degree range; and DB canals presenting curvatures in the 0-5 degree range. These teeth were randomly assigned to three groups, Reciproc (REC) [40.06]; Hyflex CM (HF) [40.06] [Coltene, Cuyahoga Falls, OH, USA] and Twisted file Adaptive (TFA) [35.04]. After root canal preparation, all the teeth were scanned to evaluate parameters previously cited. In particular, the percentage of negotiability of the MB2 canal was evaluated. All parameters were statistically compared using the Kruskal-Wallis and Dunn's Multiple comparison tests within groups with a significance level of 5%. For MB2 canals, no statistically significant difference was observed among the three groups with regard to the values of canal transportation, centering ability, remaining dentin thickness in the coronal third, number of specimens with thickness under 0.5 mm in the danger zone, and apical volume (P>0.05). However, the entire volume of the canal in Group MO differed statistically from that of Group PDR (P<0.05), but Group REC did not differ statistically from Groups MO and PDR (P>0.05). Group PDR demanded more time to reach WL than use of the MO and REC systems. For MB and DB canals, the trend of canal transportation was towards inner curvature in apical third, while in the coronal third it was towards the outer curve. There was no difference in apical transportation values in the first apical millimeters for both canals. In MB canal, at 3 and 4 mm, the Reciproc transportation value was significantly lower than that of Hyflex CM(P<0.05). In the DB canal, at 2 and 4 mm, Reciproc showed substantially higher values than Group TFA (P<0.05). There was no statistically significant difference between the two canals among the three systems for centering ability in the apical third and the remaining dentin thickness (RDT). For DB canal, there was no significant difference in shaping time, but in the MB canal, Group TFA was swifter than Reciproc and Hyflex CM. The initial changes in volume (apical/entire) after canal preparation was statistically significant within groups in MB and DB canals for percentage and volume of dentin removed. TFA had the lowest values for the apical and entire volumes of dentin removed in both canals compared with Reciproc and Hyflex CM (P<0.05). TFA had the lowest percentage of dentin removed from the entire MB canal, and from the apical and entire volume of DB canal. For negotiating and shaping the MB2 canal, the three file systems had similar performance. However, the REC system reached the full working length faster than PDR. The MO and REC systems removed more dentin in the inner furcation area when compared with PDR. For MB and BD canals, the heat treated NiTi alloy systems used for larger apical preparation evenly maintained the morphology of the MB and DB canals of maxillary molars. In shaping procedures, the larger apical preparation produced slight canal transportation without evidence of significant preparation errors. However, these variations may not be feasible of clinical significance. Use of TFA was swifter for preparing the MB canal and produced fewer changes in volume parameters. The TFA system was able to preserve the original canal anatomy with less canal transportation than the Reciproc and Hyflex CM systems.(AU)

O objetivo deste estudo foi avaliar o transporte do canal, a centralização do canal, a espessura dentinária, a alteração volumétrica e o tempo de trabalho de diferentes sistemas mecanizados de níquel-titânio compostos por ligas convencional (Mtwo) e tratados termicamente (CMWire (Prodesign R e Hyflex CM), M-Wire (Reciproc) e fase-R (Twisted file adaptive) em preparos de canais em molares superiores. O papel dos novos instrumentos de níquel titânio tratados termicamente em preparos apicais mais amplos de canais mésio-vestibulares e distovestibulares dos molares superiores foi avaliado, como também o preparo do canal mésiopalatino (CMP), por meio da microtomografia computadorizada (µ-CT). No estudo do canal mésio-palatino, 30 primeiros molares superiores com configuração tipo IV de Vertucci foram selecionados e divididos em 3 grupos (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. No estudo dos canais mésio-vestibulares e disto-vestibulares, o total de 45 molares superiores foram selecionados com angulação da raiz mésio vestibular de 20 a 30 graus e apresentando a raiz disto-vestibular com angulação de 0 a 5 graus, de acordo com a classificação de Weine. Os dentes foram aleatoriamente distribuídos em 3 grupos (n=15): Reciproc (40.06) [REC, VDW, Munich, Germany]; Hyflex CM (40.06) [HF, Coltene, Cuyahoga Falls, OH, USA]; e Twisted file Adaptive (35.04) [TFA, SybronEndo, Orange, CA]. Após o preparo dos canais mésio-palatino, mésio-vestibular, e disto-vestibular, todos os dentes foram escaneados para avaliação dos parâmetros previamente citados. Especificamente, na avaliação do canal mésiopalatino, foi avaliada a porcentagem de canais que alcançaram patência. Todos os parâmetros foram avaliados estatisticamente pelo teste de Kruskal-Wallis e pelo teste Dunn's de múltipla comparação entre grupos, com nível de significância de 5%. O canal mésio-palatino não apresentou diferença estatisticamente significante em relação ao transporte, centralização, remanescente de dentina no terço cervical, quanto ao número de espécime abaixo de 0,5 mm de espessura na zona de perigo e no volume apical (P>0.05). O volume total do canal no grupo MO diferenciou-se do volume total do grupo PDR (P<0.05), enquanto essa diferença não foi evidenciada entre os grupos REC comparado aos grupos MO e PDR (P>0.05). O grupo PDR demandou maior tempo para atingir o comprimento de trabalho comparado aos sistemas MO e REC. Na análise dos canais MV e DV dos molares superiores, o transporte coronal direcionou-se para o interior da curvatura do canal, enquanto no terço apical o transporte direcionou-se para o lado externo da curvatura. O transporte apical no primeiro milímetro de ambos os canais (MV e DV) foi equivalente entre os grupos (P>0.05). O canal MV apresentou nos níveis 3 e 4 mm transporte do grupo Reciproc significantemente menor do que no grupo Hyflex CM (P<0.05). Em relação ao transporte apical, no canal DV, nos milímetros 2 e 4 apicais do grupo Reciproc transportou significantemente mais comparado ao grupo TFA (P<0.05). Contudo, a centralização apical de ambos os canais e a quantidade de remanescente dentinário apical não se diferiram estatisticamente (P<0.05). O preparo do canal MV foi mais rápido com o sistema TFA comparado ao Reciproc e do Hyflex CM (P<0.05), enquanto no canal DV não foi evidenciado diferenças em relação ao tempo de preparo (P>0.05). A porcentagem e o volume de dentina removida em todo o canal e na região apical, após o preparo do canal apresentou diferenças significantes entre os grupos. O grupo TFA teve as menores porcentagens e valores de dentina removida no volume total do canal e no volume apical, em ambos os canais, comparado com os sistemas Reciproc e Hyflex CM (P<0.05). No canal MP, os três sistemas avaliados prepararam e patenciaram semelhantemente os canais MP. Contudo, o sistema Reciproc foi mais rápido para alcançar o comprimento de trabalho do que o sistema Prodesign R. Os grupos Mtwo e Reciproc removeram mais dentina na região voltada para o interior da furca quando comparado ao Prodesign R. Os sistemas compostos por ligas tratadas termicamente em preparos com maior ampliação apical mantiveram a morfologia dos canais MV e DV. Os sistemas promoveram discretos transportes, sem evidência de erros no preparo. Contudo, essas variações não são passíveis de significância clínica. O grupo do TFA foi mais rápido e promoveu menores alterações nos parâmetros volumétricos. O grupo do TFA foi capaz de preservar a anatomia original do canal com menor grau de transporte comparado ao Reciproc e Hyflex CM.(AU)

Humans , Dental Pulp Cavity/anatomy & histology , Dental Pulp Cavity/diagnostic imaging , Nickel/chemistry , Root Canal Preparation/instrumentation , Titanium/chemistry , Dental Instruments , Equipment Design , Molar/diagnostic imaging , Reference Values , Reproducibility of Results , X-Ray Microtomography/methods