In vitro study of structural and chemical changes in two reciprocating files after multiple reuses and sterilisation.

To use scanning electron microscopy and energy dispersive X-ray spectroscopy to evaluate the metallurgical-chemical changes of WaveOne Gold (WOG) and R-Motion (RM), after multiple uses. The instruments were divided into groups (n = 8): WOG and RM-control groups, new instruments; WOG1 and RM1; WOG2 and RM2; WOG3 and RM3 after instrumentation of 1, 2 or 3 molars, respectively. Burrs occurred mainly in the control group and after the first use. The RM files were found to have a higher nickel content, which increased during reuse, and a decrease in oxygen content with increasing reuse, in addition to calcium impregnation, which occurred in greater amounts in the corrosion areas in the WOG files. The presence of topographic and chemical changes was demonstrated, indicating that caution should be taken when reusing endodontic instruments to avoid fractures.

Elimination of E. faecalis and C. albicans Biofilm: A comparison between single and multiple file systems in an Ex Vivo study

To evaluate whether the WaveOne Gold and Reciproc single file instrumentation systems, are effective in reducing the microbial load of a mixed biofilm and the cleaning of apical third compared to the Twisted File Adaptive system (multiple- file system). Seventy mesial roots of the first and second molars were included and randomly divided into three experimental groups (n=20, n=10 controls). Biofilms were formed inside canals over 31 days. After instrumentation with the unique file systems, WaveOne Gold and Reciproc and the multiple file system Twisted File Adaptive, using 2.25% sodium hypochlorite as an irrigant in all cases, a count of colony forming units was performed using serial dilutions, cleaning of the apical third was evaluated using scanning electron microscopy. Comparisons amongst groups were made by using parametric and non-parametric statistics, according to a normal or non-normal data distribution, respectively. No significant differences in the reduction of the microbial load after employing a single-file system in comparison to the multiple-file system were found; in addition, the cleaning of the apical third was similar for the three different instrumentation systems. The single-file system is equal in effectiveness compared with the multiple-file system in reducing the microbial load.

Evaluar si los sistemas de instrumentación de lima única, como WaveOne Gold y Reciproc son efectivos para reducir la carga microbiana de un biofilm mixto y la limpieza del tercio apical, comparado con los sistemas de limas múltiples, como Twisted File Adaptive. Setenta raíces mesiales de primeros y segundos molares fueron incluidos y divididos de forma aleatoria en tres grupos experimentales (n=20, n=10 controles). El biofilm fue formado en el interior de los conductos durante 31 días. Después se instrumentó con los sistemas de lima única (WaveOne Gold y Reciproc) y el sistema de limas múltiples Twisted File Adaptive, usando hipoclorito de sodio al 2.5% en todos los casos. El conteo de unidades formadoras de colonias se realizó usando diluciones seriales, la limpieza del tercio apical se evaluó empleando el microscopio electrónico de barrido. La comparación entre grupos se realizó con pruebas paramétricas y no paramétricas, de acuerdo con la distribución normal y no normal de los datos, respectivamente. No hubo una diferencia significativa en la reducción de la carga microbiana después de emplear los sistemas de lima única en comparación a los de limas múltiples, además, la limpieza del tercio apical fue similar en los 3 diferentes sistemas de instrumentación. Los sistemas de lima única son igual de efectivos para reducir la carga microbiana comparados con los sistemas de limas múltiples.

Influencia de la Experiencia del Operador en la Conformación de Canales Radiculares Simulados Utilizando Waveone Gold

Evaluar la influencia del operador sobre el transporte apical y centrado de la instrumentación endodóntica utilizando WaveOne Gold en canales radiculares simulados de resina acrílica. Se asignaron 32 canales simulados de resina acrílica a dos grupos (n = 16). El grupo 1 conformado por estudiantes inexpertos y el grupo 2 por especialistas en el área de endodoncia. Estos canales se instrumentaron hasta un tamaño apical de 25/07 con lima Primary WaveOne Gold. Para evaluar el transporte apical y el centrado de la instrumentación se utilizaron imágenes fotográficas que fueron analizadas mediante los software de edición de imagen Photoshop e Image J. Además fue registrada la incidencia de fractura de instrumentos. Los datos fueron registrados mediante un formulario Google Forms y analizados mediante el software estadístico R. Se evaluó la normalidad de los dato s mediante el test Shapiro-Wilk y para establecer diferencias entre los grupos se realizó la prueba t. El nivel de significancia estadística fue establecido en p < 0,05. La mayor diferencia al evaluar el centrado se evidenció a nivel de los 6 mm y en cuanto al transporte apical la mayor discrepancia fue a nivel de 1 mm. Sin embargo, no se observaron diferencias significativas entre ambos grupos e n ninguno de los puntos evaluados. Se reportó una baja incidencia de fractura de instrumentos. La experiencia del operador no influye en la conformación del canal radicular simulado al evaluar centrado y transporte apical al utilizar limas WaveOne Gold.

To evaluate root canal transportation and centering ability as influenced by operator experience using WaveOne Gold files in simulated acrylic resin root canals. Thirty-two simulated acrylic resin canals were distributed to two groups (n = 16). Group 1 is made up of inexperienced students, and group 2 by specialists in the field of endodontics. These canals were shaped to an apical size of 07/25 with the Primary WaveOne Gold file. Photographic images were used to evaluate apical transport and centering of the instrumentation, which was analyzed using Photoshop and Image J image editing software. File separation was also recorded. The data were recorded using Google Forms and analyzed using the R statistical program. The normality of the data was evaluated using the Shapiro-Wilk test, and the t-test was performed to establish differences between the groups. The level of statistical significance was established as p <0.05. The normality of the data was evaluated using the Shapiro-Wilk test. Then statistical significance was analyzed using the T-test. The most remarkable difference when evaluating centering was evident at the 6 mm level. In terms of apical transport, the major discrepancy was at the 1 mm level. However, no significant differences were observed between both groups in any of the points evaluated. A low incidence of instrument fracture was reported. According to our results, the operator's experience does not influence shaping in simulated root canals in terms of centering ability and apical transportation when using WaveOne Gold files.

Evaluation of temperature effect on cyclic fatigue resistance of nickel-titanium instruments in a double-curved canal: a comparative study / Avaliação do efeito da temperatura na resistência a fadiga cíclica de instrumento níquel titânio em canal com dupla curvatura: estudo comparativo

Objective: To investigate the effect of room and body temperatures on cyclic fatigue resistance of three endodontic nickel-titanium rotary files: Hyflex EDM (HEDM) (Coltene/Whaledent, Switzerland), WaveOne Gold (WOG) (Dentsply Maillefer, Switzer), and EdgeOne Fire (EOF) (EdgeEndo, Albuquerque, New Mexico, USA) in a double- curved canal. Material and Methods: In this study, Sixty NiTi rotary files were used. These files were divided into three groups (n = 20 for each group). Group A: HEDM (size 25, taper 0.08), group B: WOG (size 25, taper 0.07), and group C: EOF (size 25, taper 0.07). Each group was subdivided into two subgroups (n=10 for each subgroup). One of the subgroup was subjected to cyclic fatigue test at room temperature (20±1°C), while the other subgroup was subjected to cyclic fatigue test at body temperature (37±1°C). These files were tested by using a custom-made artificial canal with a double curvature (coronal curve: 60° curvature with 5 mm radius; apical curve: 70° curvature with 2 mm radius). All instruments were rotated according to the manufacturer instructions until the fracture occurred by using electric endodontic motor (Wave One, Dentsply Maillefer, Ballaigues, Switzerland). The number of cycles to fracture (NCF) and the fractured fragment length (FL) were recorded for each endodontic file. The data were gathered and statistically analyzed using shapiro-wilk test and two-way ANOVA test. The statistical significance was set at 0.05. Results: The NCF of WOG and EOF were significantly lower at body temperature as compared to room temperature (p ≤ 0.05), whereas no difference was observed in NCF of HEDM at body and room temperatures (p>0.05). At 20±1°C, the results showed a non-significant difference between NCF of WOG and EOF (p>0.05), while the NCF of HEDM was significantly lower than the other groups (p ≤ 0.05). At 37±1°C, the results showed a non-significant difference in NCF among the tested endodontic files (p ≤ 0.05). There is non-significant difference in FL of each group at (20±1°C) and (37±1°C) (p>0.05). No statistical difference in FL among the tested files at room and body temperatures (p>0.05). Conclusion: The temperature has a significant effect on cyclic fatigue resistance of EOF and WOG, whereas no effect was observed on cyclic fatigue resistance of HEDM. WOG and EOF had a comparable NCF, while HEDM had a lower NCF than other groups at room temperature. At body temperature, all tested files have a comparable NCF. These results were attributed to the type of the alloy and heat treated that was used to manufacture these endodontic files. The cyclic fatigue test should be done at body temperature (AU)

Objetivo : Investigar o efeito das temperaturas ambiente e corpórea na resistência a fadiga cíclica em três instrumentos endodônticos rotatório de níquel-titânio: Hyflex EDM (HEDM)(coltene/Whaledent, Switzerland), WaveOne Gold (WOG) Dentsply Maillefer, Switzer), e EdgeOne Fire (EOF) (EdgeEndo, Albuquerque, New Mexico, USA) em canais com dupla curvatura. Material e Métodos : Neste estudo foram utilizadas sessenta limas endodônticas rotatórias. Esses grupos foram divididos em três grupos (n=20). Grupo A: HEDM (tamanho 25, conicidade 0.08), grupo B: WOG (tamanho 25, conicidade 0.07), e grupo C: EOF (tamanho 25, conicidade 0.07). Cada grupo foi subdivididos em dois subgrupos (n=10). Um dos subgrupos foi submetido ao teste de fadiga cíclica em temperatura ambiente (20±1°C), enquanto o outro subgrupo foi submetido a ao teste de fadiga cíclica em temperatura corpórea (37±1°C). Essas limas foram testadas em um canal artificial feito sob medida com duas curvaturas (curva coronal: curvatura de 60º e com 5 mm de raio; curva apical: curvatura de 70º com 2mm de raio); Todos os instrumentos foram rotacionados de acordo com a instrução do fabricante até que a fratura ocorresse utilizando um motor endodôntico elétrico (Wave One, Dentsply Maillefer, Ballaigues, Switzerland). O número de ciclos até a fratura (NCF) e a comprimento do fragmento fraturado (FL) foram registrados para cada lima endodôntica. Os dados foram coletados e analisados pelo teste shopiro-wilk e ANOVA two-way. A significância estatística foi 0.05. Resultados: O NCF do WOG e do WOF foi significantemente menor na temperatura corpórea em comparação à temperatura ambiente (p ≤ 0.05), enquanto não foi observada diferença entre NCF em HEDM em temperatura corpórea e temperatura ambiente (p>0.05). Em 20±1°C, os resultados mostraram diferença não significativa entre o NFC com WOG e EOF (p>0.05), enquanto o NCF com HEDM foi significante menor que os demais grupos (p ≤ 0.05). A 37±1°C, os resultados mostraram diferença não significativa em NCF entre as limas endodônticas testadas (p ≤ 0.05). Há diferença não significativa no FL de cada grupo (20±1°C) e (37±1°C) (p>0.05). Não houve diferença estatisticamente diferente no FL entre as limas testadas nas temperaturas ambiente e corporal (p>0,05). Conclusão: A temperatura tem efeito significativo na resistência a fadiga cíclica do EOF e WOG, enquanto não foi observado nenhum efeito na resistência a fadiga cíclica do HEDM. WOG e EOF tiveram um NCF comparável, enquanto HEDM teve um NCF menor do que os outros grupos em temperatura ambiente. À temperatura corporal, todas as limas testas apresentam semelhante NCF. Esses resultados foram atribuídos ao tipo de liga e ao tratamento térmico que foi utilizado na fabricação. O teste de fadiga cíclica deve ser feito à temperatura corporal (AU)

Surface profile of different heat-treated nickel-titanium files before and after root canal preparation

Abstract The aim of this study was to evaluate surface wear, presence of microcracks and surface irregularities of WaveOne (WO) and WaveOne Gold (WOG) instruments before and after multiple uses. Eight Primary instruments of the WO and WOG systems were evaluated, each one was used to prepare six mesial canals of extracted human mandibular molars. The surface of the instruments was evaluated before use (T0), after instrumentation of three (T1) and six (T2) root canals. Surface wear was analyzed using a three-dimensional optical profiler and the presence of microcracks and surface irregularities were evaluated using a tabletop scanning electron microscopy. The Friedman test was used to assess surface wear and Kruskal-Wallis test to evaluate the presence of microcracks and surface irregularities, with a 5% significance level. There was a significant increase in wear in both groups at T2, compared to T0 (p=0.0003). The surface wear after instrumentation of six canals (T2-T0) was statistically greater in the WOG group, than in the WO group (p=0.02), where the presence of microcracks was significantly greater and increased after multiple uses (p<0.05). The presence of surface irregularities in the cutting blade before and after use was statistically greater in the WOG group than WO group (p<0.05). Wear of the cutting blade, microcracks and surface irregularities were observed on the surface topography of all the instruments after multiple uses. These surface changes may affect the cutting efficiency of WOG files and increase the risk of fracture of WO files.

Resumo O objetivo deste estudo foi avaliar o desgaste de superfície, a presença de microtrincas e irregularidades superficiais dos instrumentos WaveOne (WO) e WaveOne Gold (WOG) antes e após múltiplos usos. Oito instrumentos Primary dos sistemas WO e WOG foram avaliados, cada um utilizado no preparo de seis canais mesiais de molares inferiores humanos extraídos. A superfície dos instrumentos foi avaliada antes do uso (T0), após a instrumentação de três (T1) e seis (T2) canais radiculares. O desgaste de superfície foi analisado utilizando um perfilômetro ótico tridimensional e a presença de microtrincas e irregularidades superficiais foram avaliadas usando um microscópio eletrônico de varredura de bancada. O teste de Friedman foi usado para avaliar o desgaste de superfície e o teste de Kruskal-Wallis para avaliar a presença de microtrincas e irregularidades superficiais, com nível de significância de 5%. Houve um aumento significativo no desgaste em ambos os grupos em T2, comparado a T0 (p=0.0003). O desgaste de superfície após a instrumentação de seis canais (T2-T0) foi estatisticamente maior no grupo WOG que no grupo WO (p=0.02), onde a presença de microtrincas foi estatisticamente maior e aumentou após os múltiplos usos (p<0.05). A presença de irregularidades na superfície da lamina de corte antes e após o uso aumento significativamente no grupo WOG comparado ao grupo WO (p<0.05). Desgaste da lâmina de corte, microtrincas e irregularidades superficiais foram observadas na topografia de superfície de todos os instrumentos após os múltiplos usos. Essas alterações na superfície podem afetar a eficiência de corte dos instrumentos WOG e amentar o risco de fratura dos instrumentos WO.

Effect of number of uses and sterilization on the instrumented area and resistance of reciprocating instruments.

OBJECTIVES: This study evaluated the effect of repeated uses and autoclaving in the instrumented area, fracture resistance, and time of instrumentation of thermally treated nickel-titanium reciprocating systems. MATERIALS AND METHODS: Two hundred simulated canals were instrumented using Reciproc Blue and WaveOne Gold. Each file was used up to 10 times or until fracture. The instrumented area was measured in pre- and post-operative images, using ImageJ software. Kaplan-Meier survival analysis evaluated the number of uses of instruments before fracture. Instrumented area and time of instrumentation were analyzed by Mann-Whitney U test and Kruskal-Wallis. Correlations among the number of uses and instrumented area were measured. The level of statistical significance was set at p < 0.05. RESULTS: Reciproc Blue presented a higher estimated number of uses in comparison with WaveOne Gold (p = 0.026), but autoclaving did not affect the resistance to fracture of instruments (p > 0.05). The instrumented area was different among the evaluated groups (p = 0.039), and the instrumented area along the uses of both tested instruments was reduced. With the time of instrumentation, there was also a significant difference among the evaluated groups; the groups without sterilization cycles were faster, in comparison to those submitted to autoclaving (p = 0.010). CONCLUSIONS: Reciproc Blue was more resistant than WaveOne Gold, suffering later fracture. Additionally, the sterilization cycles did not influence the estimated number of uses of thermally treated reciprocating instruments, but the instrumented area of root canals was reduced along with the repeated uses of both instruments.

Effect of Foraminal Enlargement on Postoperative Pain in Necrotic Single-Rooted Teeth: A Randomized Clinical Trial.

INTRODUCTION: The aim of this study was to evaluate pain perception, pain medication intake, and sealer extrusion after single-visit root canal treatment of asymptomatic teeth with or without foraminal enlargement. The correlation between sealer extrusion and pain was also investigated. METHODS: One hundred forty necrotic, single-rooted teeth were divided into 2 groups (n = 70): foraminal patency (FP), in which treatment was performed up to 1 mm short of the apex, and foraminal enlargement (FE), in which treatment was performed up to the apex. The canals were instrumented using WaveOne Gold files (Dentsply Maillefer, Ballaigues, Switzerland), irrigated with 2.5% sodium hypochlorite, and filled using the single-cone technique and AH Plus sealer (Dentsply Maillefer). A visual analog scale was used to record pain 24, 48, and 72 hours and 1 week postoperatively. The presence or absence of sealer extrusion was recorded. RESULTS: Pain levels were significantly higher for FE than FP at 24 hours (P < .05), namely 0.3 ± 0.9 versus 0.1 ± 0.1; no difference was found at 48 hours, namely 0.1 ± 0.5 versus 0.0 ± 0.0 (P > .05). No pain was reported 72 hours or 1 week postoperatively in either group. Although all patients requiring pain medication at 24 hours were from the FE group, the difference between FE and FP was not statistically significant with respect to this variable (P > .05). Nevertheless, the intake amount was significantly higher in FE than in FP at this time point (P < .05). Sealer extrusion occurred more frequently in FE than FP, namely 57.14 % versus 14.29% (P < .05). There was no association between pain and sealer extrusion (P > .05) or between pain and sex, age, or tooth type (P > .05). CONCLUSION: FE was related to higher pain levels 24 hours postoperatively and to higher rates of filling material extrusion; however, there was no association between filling material extrusion and postoperative pain.

Root dentine thickness in C-shaped lower second molars after instrumentation: A CBCT and micro-CT study.

Stripping perforation is a possible complication in instrumentation of C-shaped canals. This study evaluated the minimum thickness of the root canal wall in C-shaped teeth after instrumentation. Twelve extracted C-shaped mandibular second molars (four teeth of type I, II and III each) were examined by CBCT (voxel size 90 µm) before and after instrumentation with WOG primary file. Micro-CT scans (voxel size 30 µm) were obtained after instrumentation. Percentage of canal wall area touched by the file and minimum thickness of dentine were measured and compared between CBCT and micro-CT. In type I C-shape canals, less than 10% of the canal wall area was touched by the instrument. In ten teeth, the shortest distance to root surface was from the instrumented area; no perforations occurred. CBCT and micro-CT measurements were in good agreement in ten cases; in two teeth, micro-CT revealed considerably shorter distance to root surface. The two shortest distances were 0.27 and 0.41 mm.

Three-dimensional analysis of the root canal preparation with Reciproc Blue®, WaveOne Gold® and XP EndoShaper®: a new method in vivo.

BACKGROUND: The purpose of this study was to evaluate the changes in canal volume after root canal preparation in vivo with 3 different single-file techniques (Reciproc-Blue®, WaveOne-Gold® and XP-EndoShaper®), with a new method using CBCT and 3D reconstruction. METHODS: In this prospective study, thirty human lower premolars from healthy patients were used, in which extraction was indicated for orthodontic reasons. All the teeth used were caries- and restoration-free with complete root development, without signs of periodontal disease or traumatic occlusion, and with only one straight canal (up to 25º curvature). Teeth were randomly divided into three different groups: Reciproc-Blue, WaveOne-Gold and XP-EndoShaper. CBCT scans before root canal preparation were used to create a 3D reconstruction with RHINOCEROS 5.0 software to assess the initial canal volume, and then compared with 3D reconstructions after canal preparation to measure the increase in canal volume. Student's t test for paired data were used to determine statistically significant differences between the before and after canal volumes. Anova test was used to determine statistically significant differences in the percentage of canal volume increase between the groups and Tukey's post-hoc test were used to paired comparison. RESULTS: Reciproc-Blue showed the higher increase in canal volume, followed by WaveOne-Gold and XP-EndoShaper (p = 0.003). XP-EndoShaper did not show a statistically significant increase in canal volume after root canal preparation (p = 0.06). CONCLUSION: With this model, Reciproc-Blue showed higher increase in root canal volume, followed by WaveOne-Gold, while XP-EndoShaper did not significantly increase root canal volume during preparation.

Avaliação das propriedades físico-químicas de instrumentos reciprocantes de níquel-titânio tratados termicamente / Evaluation of the physicochemical properties of heat-treated nickel-titanium reciprocating instruments

Os instrumentos endodônticos de níquel-titânio acionados a motor foram desenvolvidos para se obter um preparo químico-mecânico mais rápido e seguro, no entanto, esses instrumentos apresentam como desvantagem o risco de fraturar durante o seu uso. Diante disso, os fabricantes têm desenvolvido mudanças no design dos instrumentos, nos acabamentos das ligas e na cinemática de uso, pois são características que contribuem para que as fraturas aconteçam. O objetivo deste estudo foi avaliar e comparar propriedades mecânicas de novos instrumentos de níquel-titânio com memória controlada lançados no mercado. Os sistemas WaveOne Gold (WOG; Dentsply Sirona, Ballaigues, Switzerland), WA1 File (WA1; TDKaFile, Cidade do México, México) e X1 File (X1; MK Life, Porto Alegre, RS, Brasil) foram submetidos ao teste de resistência à torção, de acordo com a norma ISO 3630-1, ao teste rigidez à flexão, através do ensaio de flexão em cantiléver (45º) e ao teste de resistência à flambagem. Os resultados foram avaliados através da análise de variância (ANOVA), o teste F e o teste de Tukey, considerando um nível de significância de 5%. No teste de resistência à torção os instrumentos WOG apresentaram maior deflexão angular, ou seja, maior resistência à fratura em torção, enquanto os instrumentos WA1 a menor e na comparação do torque máximo em torção não houve diferença estatística significante entre os sistemas. Nos testes de rigidez a flexão e resistência à flambagem houve diferença estatística significante entre os 3 sistemas, sendo os instrumentos X1 os mais rígidos. No primeiro teste os instrumentos WA1 se apresentaram como os mais flexíveis e no segundo, os instrumentos WOG. Conclui-se que os instrumentos WOG, WA1 e X1 mostraram diferenças estatísticas nos testes mecânicos, sendo os instrumentos WOG e WA1 os mais resistentes à fratura por torção e os mais flexíveis, diferentemente dos instrumentos X1 que se apresentaram mais susceptíveis à fratura por torção e menos flexíveis (AU)

Reciprocating nickel-titanium endodontic instruments have been developed to obtain a faster and safer preparation, however, these instruments have the disadvantage of fracturing during use. Facing this disadvantage, manufacturers have developed changes in instrument design and alloy finishes, as metallurgical characteristics are one of the factors that contribute to fractures. The aim of this study was to evaluate and compare mechanical properties of new nickel-titanium instruments with controlled memory. The WaveOne Gold (WOG; Dentsply Sirona, Ballaigues, Switzerland), WA1 File (WA1; TDKaFile, Mexico City, Mexico) and X1 File (X1; MK Life, Porto Alegre, RS, Brazil) systems were subjected to the torsional fatigue test, according to the ISO 3630-1 standard, flexural stiffness test, through the cantilever flexion test (45°) and buckling resistance test. The results were evaluated through analysis of variance (ANOVA), the F test and the Tukey test, considering a significance level of 5%. In the torsional fatigue test, the WOG instruments showed greater angular deflection, that is, greater resistance to torsional fracture and the WA1 instruments the lesser, and when comparing the maximum torsional torque, there was no statistically significant difference between the systems. In the flexural stiffness and buckling resistance tests, there was a statistically significant difference between the 3 systems, with the X1 instruments being the most rigid. In the first test, the WA1 instruments were the most flexible followed by the WOG instruments. In conclusion, the WOG, WA1 and X1 instruments showed differences in the mechanical tests, with the WOG and WA1 instruments being the most resistant to torsion fracture and the most flexible, unlike the X1 instruments that were more susceptible to torsion fracture and also the most rigid (AU).

Fracture incidence of WaveOne Gold files: a prospective clinical study.

AIM: This prospective clinical study evaluated the incidence of instrument fracture observed after single-file root canal treatment of molars using WaveOne Gold instruments. METHODOLOGY: Three standardized, experienced and calibrated specialists treated 750 maxillary and mandibular molars with curvatures less than 45° (2691 root canals) over a 12-month period. All the treatments were performed in a single session. A total of 1104 WaveOne Gold instruments were used, including 38 small, 750 primary, 228 medium and 88 large instruments. Intracanal procedures were performed according to the manufacturer's recommendations, and each instrument was used in a single clinical case. The instruments were examined after their removal from the canal, under an operating microscope at 8× magnification. RESULTS: No fractures were observed in any of the 1104 instruments used. CONCLUSIONS: No fractures of WaveOne Gold reciprocating instruments occurred during root canal preparations performed in maxillary and mandibular molars with curvatures less than 45° when used strictly according to the manufacturer's recommendations and applied in a single clinical case.

Influence of the Preparation Order in Four-Canal Maxillary Molars with WaveOne Gold System.

INTRODUCTION: The aim of this study was to evaluate the effect of the order of preparation of four-canal maxillary molars on volume variation, instrument deformation, cyclic fatigue, and preparation time by using the WaveOne Gold Primary (WOG 25.07). METHODS: We selected 48 permanent, human, four-canal maxillary molars. The teeth were divided into 4 groups according to the order of initiation of the canal preparation sequence: (1) mesiobuccal (MB), distobuccal (DB), palatal (P), second mesiobuccal (MB2); (2) DB-P-MB2-MB; (3) P-MB2-MB-DB and (4) MB2-MB-DB-P. Pre- and post-preparation microtomography scanning was performed to obtain initial and final canal volume measurements. The instruments were also evaluated by using scanning electron microscopy to determine the wear and deformation present after use. The active instrumentation time was also recorded. The data were statistically compared by using a significance level of 5%. RESULTS: No statistically significant difference was found between groups for volume variation and time of preparation of the canals with the WOG system (P > .05); however, a statistically significant difference was observed in the deformation of the instruments. In the comparison between the groups for MB-DB-P-MB2 and P-MB2-MB-DB, the latter presented greater deformation of the instruments. CONCLUSIONS: Root canal preparation sequence affected deformation of the instruments but did not influence the volume variation or the canal preparation time with the WOG system. To minimize instrument deformation, the preparation order should be MB-DB-P-MB2.

Torsional fatigue resistance of R-Pilot and WaveOne Gold Glider NiTi glide path reciprocating systems.

AIM: To evaluate the torsional properties of the NiTi glide path reciprocating instruments R-Pilot (VDW, Munich, Germany) and WaveOne Gold Glider (Dentsply Sirona, Ballaigues, Switzerland). METHODOLOGY: Ten R-Pilot (size 12.5, .04 taper) and 10 WaveOne Gold Glider (size 15, .02v taper) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. Three millimetres of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Data were analysed using the Student t-test at a significance level of P < 0.05. RESULTS: The maximum torsional strength of the R-Pilot instruments was greater than the WaveOne Gold Glider (P < 0.05). In contrast, WaveOne Gold Glider instruments had significantly higher angular rotation to fracture than R-Pilot instruments (P < 0.05). The scanning electron microscopy of the fracture surfaces revealed similar and typical features of torsional failure (ductile type) for both brands. The torsional failure displayed two zones: the first with microvoids in the centre of the instruments (core) and the second one represented by plastic deformation around the microvoids; this configuration occurred because of the shear stresses originated during the twisting. CONCLUSIONS: R-Pilot instruments had a lower angle of rotation to fracture but a higher torque to failure than WaveOne Gold Glider instruments.

Estudio comparativo de la conformación generada con las limas ProGlider y WaveOne Gold Glider en conductos curvos simulados / A comparative study of the shaping ability generated with ProGlider and WaveOne Gold Glider in simulated curved canals

Objetivo: Comparar, en conductos curvos simulados de Endo Training Blocks, la conformación alcanzada por las limas ProGlider y WaveOne Gold Glider. Materiales y métodos: Se utilizaron 20 Endo Training Blocks con conductos curvos. Los conductos fueron teñidos con tinta china. Los bloques fueron divididos al azar en dos grupos, A y B, de 10 bloques cada uno. En el grupo A los conductos se permeabilizaron y conformaron con limas ProGlider, y en el grupo B, con limas WaveOne Gold Glider, accionadas con movimiento rotatorio y reciprocante, respectivamente. Para realizar la evaluación, los conductos se dividieron en tres tercios (cervical, medio y apical), para lo cual se colocó debajo de cada bloque una hoja milimetrada, y en esa posición fueron fotografiados. Se observaron las imágenes y se estableció la siguiente categorización: 0, no conformado; 1, conformación parcial; 2, conformado. La comparación entre los dos grupos dentro de cada tercio fue realizada por medio de la prueba de Chi cuadrado o de la prueba exacta de Fisher, según correspondiera. La comparación entre tercios dentro de cada grupo fue efectuada con la prueba de Friedman. En ambos casos se fijó el nivel de significancia en P<0,05. Resultados: En los tres tercios evaluados, el WaveOne Glod Glider mostró mejores resultados que el ProGlider, obervándose diferencias estadísticas significativas entre los grupos dentro de cada tercio. La comparación entre tercios dentro de cada grupo mostró, en el grupo A, ausencia de diferencias significativas entre los tercios cervical y medio, en tanto el tercio apical fue significativamente diferente a los otros dos; en el grupo B hubo diferencias estadísticas significativas entre el tercio cervical y el medio, mientras no las hubo entre el apical y los otros dos. Conclusiones: En los tres tercios evaluados, el WaveOne Gold Glider mostró mejores resultados que el ProGlider (AU)

Aim: To compare in simulated curved canals of Endo Training Blocks, the shaping ability of ProGlider and WaveOne Gold Glider files. Materials and methods: Twenty Endo Training Blocks with curved canals were used. The simulated canals were dyed with China ink. The blocks were randomly assigned to two groups, A and B, of 10 blocks each. Group A canals were shaped with ProGlider files and group B ones with WaveOne Gold Glider files, operated with rotary and reciprocating motion respectively. For the evaluation, the canals were divided into three thirds (cervical, middle and apical). A sheet of graft paper was placed under each block and they were photographed. The images were observed and the following score was established: 0, not shaped; 1, partially shaped; 2, shaped. The comparison between the two groups within each third was made by means of the chi-square test or Fisher's exact test as appropriate. The comparison between thirds within each group was made by means of Friedman's test. In both cases, the level of significance was set at P<0.05. Results: WaveOne Gold Glider showed better results than ProGlider in the three evaluated thirds. Statistical significant differences were detected between groups in each third. The comparison between thirds within each group showed, in group A, no significant differences between the cervical and middle thirds, while the apical third presented significant differences with the other two. In group B, significant differences were observed between the cervical and middle thirds, while there were none between the apical and the other two thirds. Conclusions: In the three thirds evaluated, WaveOne Gold Glider showed better results than ProGlider (AU)

Substance P and Calcitonin gene-related peptide expression in human periodontal ligament after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files.

AIM: To quantify Substance P (SP) and Calcitonin gene-related peptide (CGRP) expression in healthy human periodontal ligament from premolars after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files. METHODOLOGY: A total of 50 human periodontal ligament samples were obtained from healthy mandibular premolars where extraction was indicated for orthodontic reasons. Prior to extraction, 40 of these premolars were equally divided into four groups, and root canals were prepared using four different systems: Reciproc Blue, WaveOne Gold, XP EndoShaper and a hand instrumentation technique. The remaining 10 healthy premolars were extracted without treatment and served as a negative control group. All periodontal ligament samples were processed, and SP and CGRP were measured by radioimmunoassay. The Kruskal-Wallis test was used to establish significant differences between groups and LSD post hoc comparisons were also performed. RESULTS: Greater SP and CGRP values were found in the hand instrumentation group, followed by the XP EndoShaper, WaveOne Gold and the Reciproc groups. The lower SP and CGRP values were for the healthy periodontal ligament group. The Kruskal-Wallis test revealed significant differences between groups (P < 0.05). Post hoc Least Significant Difference (LSD) tests revealed significant differences (P < 0.05) in SP and CGRP expression between all the comparisons except for the Reciproc Blue and WaveOne Gold group (P > 0.05). CONCLUSION: All the root canal preparation techniques tested increased SP and CGRP expression in human periodontal ligament, with hand files and XP EndoShaper instruments being associated with greater neuropeptide release compared to Reciproc Blue and WaveOne Gold files.

Eficacia de dos sistemas mecanizados para la desobturación de conductos radiculares curvos obturados con GuttaCore / Efficacy of two engine-driven systems for the removal of GuttaCore fillings from curved root canals

Objetivo: Comparar ex vivo la eficacia del instrumento WaveOne Gold Primary con la del sistema ProTaper Retratamiento para la remoción del material de obturación en conductos mesiales de molares inferiores obturados con GuttaCore y sellador. Materiales y métodos: Se seleccionaron raíces mesiales de 15 molares inferiores humanos extraídos con dos conductos radiculares cada una, forámenes independientes y curvaturas de entre 20o y 40o. Los conductos se prepararon con el sistema WaveOne Gold hasta una longitud de trabajo prefijada y hasta el instrumento Primary. La irrigación fue realizada con NaClO al 2,5%. Todos los conductos fueron obturados mediante GuttaCore empleando el obturador Primary y el sellador AH Plus con el agregado de una gota de azul de metileno al 1%. Los 30 conductos (15 mesio-vestibulares y 15 mesio-linguales) fueron divididos al azar en dos grupos de 15 (n=15) conductos cada uno. Los del grupo 1 fueron desobturados con el instrumento de movimiento recíproco WaveOne Gold Primary; los del grupo 2, con el sistema rotatorio ProTaper Retratamiento. Las muestras fueron incluidas en bloques de resina acrílica y se realizaron secciones transversales de 1 mm de espesor a nivel de 1,5, 3 y 9 mm de la longitud de trabajo con micrótomo para tejidos duros. Luego se observaron con un microscopio óptico bajo luz reflejada y se fotografiaron con una cámara digital. Las imágenes se analizaron mediante un programa informático. En cada grupo y en cada uno de los niveles prefijados, los resultados fueron expresados como la diferencia entre el área cubierta por restos de gutapercha/sellador y el área total perimetral del conducto radicular, y analizados mediante ANOVA y la prueba de Tukey, con un nivel de significación de P<0,05. Resultados: Se observaron remanentes del material de obturación en todos los niveles de ambos grupos. No hubo diferencias significativas (P>0,05) entre grupos. Las diferencias observadas entre los niveles prefijados fueron significativas (P<0,05), especialmente cuando se compararon los resultados obtenidos a 1,5 y 9 mm de la longitud de trabajo. Conclusiones: El empleo de WaveOne Gold Primary o ProTaper Retratamiento no permitió remover completamente el material de obturación en conductos mesiales de molares inferiores obturados con GuttaCore y AH Plus (AU)

Cyclic Fatigue Resistance of WaveOne Gold, ProDesign R and ProDesign Logic Files in Curved Canals In Vitro.

INTRODUCTION: Endodontic instruments are developed to provide a better cleaning of the root canal system and reduce its risk of fracture. The aim of this study was to evaluate the instrumentation time and cyclic fatigue resistance of WaveOne Gold, ProDesign R and ProDesign Logic files. METHODS AND MATERIALS: Thirty Nickel-titanium (NiTi) rotary instruments were divided into 3 groups (n=10). ProDesign Logic file 25/0.06 was used in continuous rotation after glide path preparation. WaveOne Gold 25/0.07 and ProDesign R 25/0.06 files were used in reciprocating motion. Every file instrumented 3 standardized artificial canals. The average time, the number of cycles (NCI) and cyclic fatigue resistance of each file were determined through the number of cycles to failure (NCF) in a stainless-steel device. The total amount of cycles to fracture was also calculated (NCI+NCF). Data was analyzed using the Kruskal-Wallis and Mann-Whitney tests. RESULTS: The instrumentation time of the ProDesign Logic file was significantly lower when compared to the other files (P=0.019). The longest times to failure were presented by ProDesign Logic (182.07 sec) and ProDesign R (152.38 sec) files. The same differences were observed for the NCF (910.37 and 761.93). The WaveOne Gold group presented a lower NCF as well as a smaller sum of NCI+NCF (748.33) that was statistically significant when compared to the other groups (P<0.05) respectively. CONCLUSION: The use of continuous rotational motion in canals with a glide path in the ProDesign Logic group led to shorter instrumentation time. The cyclic fatigue resistance of ProDesign R and Logic instruments was superior to WaveOne Gold. The thermal treatment of the instrument's alloy, its cross section and the glide path seems to influence the cyclic fatigue resistance.

Effect of Reciprocating Systems and Working Lengths on Apical Microcrack Development: a micro-CT Study

Abstract The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 µm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentation, and no new apical microcrack was detected. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. Root canal preparation with WaveOne Gold and Unicone, regardless of the working length, was not associated with apical microcrack formation.

Resumo O objetivo deste estudo foi avaliar o efeito da instrumentação de canais radiculares utilizando sistemas reciprocantes de lima única em diferentes comprimentos de trabalho sobre o desenvolvimento de microfissuras apicais utilizando imagens de microtomografia computadorizada (micro-CT). Quarenta incisivos inferiores humanos extraídos foram distribuídos aleatoriamente em 4 grupos (n=10) de acordo com os sistemas e comprimentos de trabalho utilizados para preparar os canais radiculares: Grupo A - WaveOne Gold no forame apical (FA), Grupo B - WaveOne Gold 1 mm aquém do FA (FA-1 mm), Grupo C - Unicone (FA) e grupo D - Unicone (FA-1 mm). Escaneamentos de micro-CT foram realizados antes e após o preparo dos canais a uma resolução isotrópica de 14 μm. Em seguida, três examinadores avaliaram as imagens de secção transversal geradas para detectar microfissuras na porção apical das raízes. Microfissuras apicais foram visualizadas em 3, 1, 1 e 3 espécimes nos grupos A, B, C e D, respectivamente. Todas essas microfissuras observadas após o preparo dos canais radiculares já existiam antes da instrumentação e não foi detectada nenhuma nova microfissura apical. Para todos os grupos, o número de cortes apresentando microfissuras após o preparo dos canais radiculares foi o mesmo verificado antes do preparo dos canais. A instrumentação de canais radiculares utilizando WaveOne Gold e Unicone, independentemente do comprimento de trabalho, não foi associada à formação de microfissuras apicais.

WaveOne Gold, un nuevo instrumento reciprocante para la conformación de los conductos radiculares / WaveOne Gold, a new reciprocating instrument for root canal shaping

El objetivo del presente artículo es describir y analizar el nuevo sistema de limas reciprocantes WaveOne Gold, evolución del sistema WaveOne presentado en 2010. Las mejoras en su diseño y en su metalurgia les otorgan más flexibilidad y aumentan su resistencia a la fatiga cíclica, lo cual brinda al clínico la posibilidad de instrumentar con más seguridad y confianza el sistema de conductos radiculares.

The aim of the present article is to describe and analyzethe new reciprocating system WaveOne Gold.This instrument, preceded by the WaveOne in 2010, showsimprovements in its design and in its metallurgy, providingmore flexibility and increasing its resistance to cyclic fatigue.Alfie D, García G, Rodríguez P. WaveOne Gold, un nuevo instrumento reciprocante para la conformaciónde los conductos radiculares. Rev Asoc Odontol Argent 2016;105:78-82.This gives the clinician greater security and confidence duringthe shaping of the root canal system.

Bending Resistance and Cyclic Fatigue Life of a new Single-File Reciprocating Instrument Waveone Gold.

OBJECTIVE: The present study aimed to evaluate the bending resistance and cyclic fatigue fracture resistance of a new single-file reciprocating instrument called WaveOne Gold. Reciproc and WaveOne instruments were used as references for comparison. METHODS: Sixty 25-mm NiTi instruments (Reciproc R25, WaveOne Primary and WaveOne Gold Primary) were tested. Flexibility was determined by applying 45° bending tests using a universal testing machine (n=10). A custom-made device was used during cyclic fatigue test (n=10), comprising a stainless steel artificial canal measuring 1.4 mm in diameter, 19 mm in total length with an 86° angle and 6 mm radius of curvature. Possible deformations at the helical shaft and mode of fracture were evaluated using scanning electron microscopy analysis. Statistical analysis was performed using one-way analysis of variance. Post hoc pair-wise comparisons were performed using Tukey's test for multiple comparisons (P<0.05). RESULTS: WaveOne presented significantly higher bending resistance than the other tested systems (P<0.05), whereas Reciproc presented the lowest bending resistance (P<0.05). Reciproc revealed a significantly longer cyclic fatigue fracture resistance than the other systems (P<0.05). CONCLUSION: Although WaveOne Gold presented higher flexibility than WaveOne, no differences in the resistance to fatigue were observed between both systems. The Reciproc files were more flexible and resistant to fatigue for the angle of curvature of 86° and 6 mm radius than WaveOne and WaveOne Gold files.