Atypical Radicular Anatomy in Permanent Human Teeth: A Systematic Review.

The aim of the present study is to classify and quantify the anatomical variations of teeth in terms of form and number of root canals reported in human teeth employing the classification systems proposed previously. An electronic (PubMed) and manual search were performed to identify case reports noting any of the anatomical variations. Each alteration was studied independently. The electronic search was performed using the following keywords: anatomical aberration, root canal, permanent Dentition, case report, c-shaped canal, dens invaginatus, palato-radicular groove, palato-radicular groove, palato-gingival groove, radix entomolaris, dental fusion, dental gemination, taurodontism, dilaceration. The initial search revealed 1497 papers, of which 938 were excluded after analyzing the titles and abstracts. Therefore, 559 potential papers were considered. Of those, 140 articles did not meet the inclusion criteria. For the final revision, 419 papers were considered. We found that the mandibular first premolar had the highest prevalence of C-shaped canals. Dens invaginatus was more frequently found in the mandibular lateral incisor. Taurodontism was more prevalent in the maxillary first molar and in the mandibular first molar. Dilaceration was not clearly associated with a particular tooth. The classifications systems used in this review allowed for the better understanding and analysis of the many anatomical variations present in teeth. The variations in shape most found were dens invaginatus and radix entomolaris. The most frequently reported anatomical variation was in the number of canals.

Resistance to fracture due to cyclic fatigue of stainless steel manual files and its association to surface roughness.

The aim of this study was to evaluate the possible association between the roughness of 5 brands of stainless steel endodontic files and their resistance to fracture due to cyclic fatigue. The study included five different brands of stainless steel endodontic files: SybroEndo Triple-Flex Files (Kerr, Glendora, USA), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Switzerland), Mani Flexile Files (Mani, Tochigi- Ken, Japan), FKG K-Files (FKG, La Chaux-de-Fonds, Switzerland) and Zipperer Flexicut Files (VDW, Munich, Germany). Twelve files per brand (total 60 files) were evaluated. File surface roughness over an area (Sa) was quantified using a focus variation microscope. Then the files were subject to a cyclical fatigue test to determine the number cycles to fracture due to fatigue and length of fractured fragment. Finally, fractographic analysis was performed using a scanning electron microscope. The electropolished Ready Steel K-Flexofile® files had the highest roughness according to Sa parameters, though they also had the highest resistance to fracture due to cyclic fatigue and the longest fractured fragment. Moderate positive correlation was found between fractured fragment length and roughness. The fractured surface showed characteristics of ductile fracture with cracks and plastic deformation. The electropolished stainless steel Ready Steel K-Flexofile® files were the most resistant to fracture due to cyclic fatigue even though they had highest surface roughness.

El objetivo del presente estudio fue evaluar la posible asociación entre la rugosidad de 5 marcas de limas endodónticas de acero inoxidable y su resistencia a la fractura por fatiga cíclica. Se incluyeron cinco grupos diferentes de limas endodónticas de acero inoxidable: SybroEndo Triple-Flex Files (Kerr, Glendora, EE. UU.), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Suiza), Mani Flexile Files (Mani, Tochigi- Ken, Japón), FKG K-Files (FKG, La Chaux-de-Fonds, Suiza) y Zipperer Flexicut Files (VDW, Munich, Alemania); se evaluaron doce instrumentos por grupo para un total de 60 limas. Mediante un microscopio de variación focal se cuantificó la rugosidad superficial por área (Sa) de los instrumentos, posteriormente fueron sometidos a una prueba de fatiga cíclica donde se determinó el número de ciclos de fractura por fatiga y la longitud del fragmento fracturado. Finalmente, se realizó un análisis fractográfico mediante microscopía electrónica de barrido. Las limas Ready Steel K-Flexofile® con electropulido mostraron el mayor valor de rugosidad en los parámetros Sa; sin embargo, también tenían la mayor resistencia a la fractura por fatiga cíclica y la mayor longitud del fragmento fracturado del instrumento. Además, se encontró una correlación moderada positiva entre la longitud del fragmento fracturado y la rugosidad. La superficie fracturada mostró características de fractura dúctil con grietas y deformación plástica. Las limas Ready Steel K-Flexofile® fabricadas en acero inoxidable con electropulido, fueron más resistentes a la fractura por fatiga cíclica a pesar de tener la mayor rugosidad superficial.

Shot peening increases resistance to cyclic fatigue fracture of endodontic files.

The objective of this study was to assess the resistance to fatigue fracture of conventional nickel-titanium files after undergoing shot peening. Forty NITIFLEX endodontic files, number 30, were divided into two groups; one was submitted to shot peening treatment and the other was not. All instruments were tested for fatigue fracture in simulated canals with a TRI-AUTO ZX endodontic motor. One file of each group was subjected to a residual stress analysis by XRD. Finally, the fractured surface was observed and elemental analysis performed by means of SEM and EDX. Roughness analysis was made by focal variation microscope. The shot peening group showed greater resistance to fatigue fracture; there was no difference in the length of the fractured fragments. XRD results showed the presence of residual compression stresses in the file submitted to shot peening, a decrease in the interplanar spacing, and an increase in the full-width-at-half-maximum and the microstrains. SEM and EDX showed a ductile fracture with zones of fatigue and an equiatomic ratio between the nickel and titanium. Surface roughness increased after the file was subjected to the shot peening procedure. In conclusion, shot peening increases the resistance to fatigue fracture due to the presence of residual compression stresses in files manufactured from a conventional nickel-titanium alloy.

Resistance to fracture due to cyclic fatigue of stainless steel manual files and its association to surface roughness / Resistencia a la fractura por fatiga cíclica de las limas manuales de acero inoxidable y su relación con la rugosidad superficial

ABSTRACT The aim of this study was to evaluate the possible association between the roughness of 5 brands of stainless steel endodontic files and their resistance to fracture due to cyclic fatigue. The study includedfive different brands of stainless steel endodontic files: SybroEndo Triple-Flex Files (Kerr, Glendora, USA), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Switzerland), Mani Flexile Files (Mani, Tochigi- Ken, Japan), FKG K-Files (FKG, La Chaux-de-Fonds, Switzerland) and Zipperer Flexicut Files (VDW, Munich, Germany). Twelve files per brand (total 60 files) were evaluated. File surface roughness over an area (Sa) was quantified using a focus variation microscope. Then the files were subject to a cyclical fatigue test to determine the number cycles to fracture due to fatigue and length of fractured fragment. Finally, fractographic analysis was performed using a scanning electron microscope. The electropolished Ready Steel K-Flexofile® files had the highest roughness according to Sa parameters, though they also had the highest resistance to fracture due to cyclic fatigue and the longest fractured fragment. Moderate positive correlation was found between fractured fragment length and roughness. The fractured surface showed characteristics of ductile fracture with cracks and plastic deformation. The electropolished stainless steel Ready Steel K-Flexofile® files werethe most resistant to fracture due to cyclic fatigue even though they had highest surface roughness.

RESUMEN El objetivo del presente estudio fue evaluar la posible asociación entre la rugosidad de 5 marcas de limas endodónticas de acero inoxidable y su resistencia a la fractura por fatiga cíclica. Se incluyeron cinco grupos diferentes de limas endo-dónticas de acero inoxidable: SybroEndo Triple-Flex Files (Kerr, Glendora, EE. UU.), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Suiza), Mani Flexile Files (Mani, Tochigi-Ken, Japón), FKG K-Files (FKG, La Chaux-de-Fonds, Suiza) y Zipperer Flexicut Files (VDW, Munich, Alemania); se evaluaron doce instrumentos por grupo para un total de 60 limas. Mediante un microscopio de variación focal se cuantificó la rugosidad superficial por área (Sa) de los instrumentos, posteriormente fueron sometidos a una prueba de fatiga cíclica donde se determinó el número de ciclos de fractura por fatiga y la longitud del fragmento fracturado. Finalmente, se realizó un análisis fractográfico mediante microscopía electrónica de barrido. Las limas Ready Steel K-Flexofile® con electropulido mostraron el mayor valor de rugosidad en los parámetros Sa; sin embargo, también tenían la mayor resistencia a la fractura por fatiga cíclica y la mayor longitud del fragmento fracturado del instrumento. Además, se encontró una correlación moderada positiva entre la longitud del fragmento fracturado y la rugosidad. La superficie fracturada mostró características de fractura dúctil con grietas y deformación plástica. Las limas Ready Steel K-Flexofile® fabricadas en acero inoxidable con electropulido, fueron más resistentes a la fractura por fatiga cíclica a pesar de tener la mayor rugosidad superficial.

Comparison of Mechanical and Structural Properties of Nickel-titanium Alloy with Titanium-molybdenum Alloy and Titanium-niobium Alloy as Potential Metals for Endodontic Files.

Introduction: The objective of this study was to compare the mechanical and structural properties of the nickel-titanium (Ni-Ti) alloy already used in endodontics with titanium-molybdenum (Ti-Mo) and titanium-niobium (Ti-Nb) alloys to determine if these can be suggested in the manufacture of endodontic files. Methods and Materials: Orthodontic wires made of the different alloys were used. The previously mentioned alloys were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and torsion tests. Cyclic fatigue tests were performed on a simulated canal with a curvature of 86° to 375 rpm. The fractured surfaces of the wires were observed by means of scanning electron microscopy (SEM). A Kruskal-Wallis test and U Mann Whitney test were used to determine significant differences in cyclic fatigue between groups. Results: In the mechanical tests, similar values of torsion were found for the three alloys. In XRD, the Ti-Nb showed less structural changes. In the cyclic fatigue test, Ti-Nb was found to be significantly more resistant with respect to Ni-Ti and Ti-Mo. Conclusion: Based on our in vitro study, Ti-Nb is suggested as a possible alloy for the manufacture of rotary files due to its impressive properties.

Application of Cutting-Tool Concepts to Endodontic Files to Achieve Better Design: A Review.

Cutting efficiency of endodontic files (EFs) has been widely evaluated in the literature. However, its performance depends on the microgeometry of the cutting instrument itself, and this has not been studied in depth. The present review describes basic concepts of cutting instruments, including cutting-tool engineering, the EF relationship, and cutting efficiency among different EF geometric designs during primary treatment and nonsurgical endodontic retreatment.

Pulp revascularization with and without platelet-rich plasma in two anterior teeth with horizontal radicular fractures: a case report.

Pulp revascularization is an alternative treatment in immature traumatized teeth with necrotic pulp. However, this procedure has not been reported in horizontal root fractures. This is a case report of a 9-year-old patient with multiple horizontal root fractures in 2 upper central incisors that were successfully treated with pulp revascularization. The patient presented for treatment 2 years after the initial trauma, and revascularization was attempted after the initial treatment with calcium hydroxide had failed. Prior to pulp revascularization, cone-beam computed tomography and autoradiograms demonstrated multiple horizontal fractures in the middle and apical thirds of the roots of the 2 affected teeth. Revascularization was performed in both teeth; platelet-rich plasma (PRP) was used in one tooth (#11) and the conventional method (blood clot) was used in the other tooth (#21). Clinical and radiographic follow-up over 4 years demonstrated pulp calcification in the PRP-treated tooth. Neither of the 2 teeth were lost, and the root canal calcification of tooth #11 was greater than that of tooth #21. This case suggests that PRP-based pulp revascularization may be an alternative for horizontal root fractures.

Factors associated to apical overfilling after a thermoplastic obturation technique - Calamus® or Guttacore®: a randomized clinical experiment.

The aims of this study were to analyze whether age, tooth type and sex are related to radiographically visible extrusion of filling material as an unintended outcome in teeth undergoing endodontic treatment with a thermoplastic obturation technique (Calamus® or GuttaCore®) and to determine whether the presence of such overfilling is associated to postoperative pain. We selected 120 teeth with diagnoses involving vital pulp and indication for endodontic treatment. Biomechanical preparation was performed using the Protaper Next® system with X2 or X3 master apical file. Teeth were randomly divided into 2 groups (n=60). Teeth in Group 1 were filled with the Guttacore® system and teeth in Group 2 were filled with single cone technique and Calamus® obturation system. Thermoplastic obturation techniques were found to cause overfilling in 53. 33% of the total cases (64 teeth) (56. 66% in Guttacore® group and 50% in the Calamus® group). Anterior teeth were found to be associated to presence of overfilling (p= 0. 024) (OR = 4. 35). Of the 120 teeth treated, 10 (8. 33%) presented postoperative pain and radiographically visible overfilling. The association between presence of extruded filling material and mild/moderate pain was statistically significant withp = 0. 002. To conclude, endodontic thermoplastic obturation with Guttacore® and Calamus® systems are significantly associated with the probability of filling material extrusion, and overfilling is associated to postoperative pain. Anterior teeth are 4 times more likely to be overfilled with the obturation techniques tested.

Los objetivos de esta investigación fueron: Analizar si factores como la edad, el tipo de diente y el género están asociados con la extrusión de material obturador radiográficamente visible como desenlace imprevisto en dientes sometidos a tratamiento endodóntico con una técnica de obturación termoplástica (Calamus® o GuttaCore®) y determinar si la presencia de esta sobreobturación está asociada con dolor posoperatorio. Se seleccionaron 120 dientes con diagnósticos que implicaban pulpa vital y con indicación de tratamiento de endodoncia. La preparación biomecánica se llevó a cabo con el sistema ProtaperNext® con lima apical principal X2 o X3. Los dientes se dividieron aleatoriamente de la siguiente forma (n=60): El grupo 1 se obturó con el sistema Guttacore® y el grupo 2 se obturó con una técnica de obturación de cono único y el sistema de obturación Calamus®. Se observó quelas técnicas de obturación termoplástica generaron sobreobturación en 53. 33% del total (64 dientes), 56. 66% se presentaron en el grupo de obturación con Guttacore® y 50% en el grupo de la técnica con el sistema Calamus®. Se encontró que los dientes anteriores presentaron asociación con la presencia de sobreobturación (p= 0. 024) (OR=4. 35). De los 120 dientes tratados, 10 (8. 33 %) presentaron dolor posoperatorio y sobreobturación radiográficamente visible. La asociación entre la presencia de extrusión de material de obturación y dolor leve-moderado fue estadísticamente significativa con un valorp= 0. 002. Como conclusión las técnicas de obturación termoplástica en endodoncia Guttacore® y el sistema Calamus® están asociadas significativamente con la probabilidad de extrusión de material obturador y dicha sobreobturación está asociada con dolor posoperatorio, los dientes anteriores presentan 4 veces más riesgo de sobreobturación con las técnicas de obturación utilizadas.

Assessment of the relationship between the maxillary sinus floor and the upper posterior root tips: Clinical considerations.

AIM: The purpose of the present study was to evaluate the relationship between the maxillary sinus floor and the upper posterior root tips in the Colombian population using cone-beam computed tomography. METHODS: A total of 1656 roots were analyzed (1104 molars and 552 premolars), classified as types I (outside the maxillary sinus) and II (inside the maxillary sinus). RESULTS: The results showed that the palatal root of the maxillary first molar was most frequently found inside the antrum. CONCLUSIONS: Understanding the relationship between the maxillary sinus floor and the upper posterior root tips is important to the clinician when performing conventional or surgical endodontic treatment and conventional surgery procedures in order to minimize or avoid the risk of damaging the maxillary sinus.

Factors associated to apical overfilling after a thermoplastic obturation technique - Calamus(R) or Guttacore(R): a randomized clinical experiment / Factores asociados con la presencia de sobreobturación apical posterior a una técnica de obturación termoplástica Calamus® o Guttacore®: experimento clínico aleatorizado

The aims of this study were to analyze whether age, tooth type and sex are related to radiographically visible extrusion of filling material as an unintended outcome in teeth undergoing endodontic treatment with a thermoplastic obturation technique (Calamus® or GuttaCore®) and to determine whether the presence of such overfilling is associated to postoperative pain. We selected 120 teeth with diagnoses involving vital pulp and indication for endodontic treatment. Biomechanical preparation was performed using the Protaper Next® system with X2 or X3 master apical file. Teeth were randomly divided into 2 groups (n=60). Teeth in Group 1 were filled with the Guttacore® system and teeth in Group 2 were filled with single cone technique and Calamus® obturation system. Thermoplastic obturation techniques were found to cause overfilling in 53.33% of the total cases (64 teeth) (56.66% in Guttacore® group and 50% in the Calamus® group). Anterior teeth were found to be associated to presence of overfilling (p= 0.024) (OR = 4.35). Of the 120 teeth treated, 10 (8.33%) presented postoperative pain and radiographically visible overfilling. The association between presence of extruded filling material and mild/moderate pain was statistically significant with p = 0.002. To conclude, endodontic thermoplastic obturation with Guttacore® and Calamus® systems are significantly associated with the probability of filling material extrusion, and overfilling is associated to postoperative pain. Anterior teeth are 4 times more likely to be overfilled with the obturation techniques tested (AU)

Los objetivos de esta investigación fueron: Analizar si factores como la edad, el tipo de diente y el género están asociados con la extrusión de material obturador radiográficamente visible como desenlace imprevisto en dientes sometidos a tratamiento endodóntico con una técnica de obturación termoplástica (Calamus® o GuttaCore®) y determinar si la presencia de esta sobreobturación está asociada con dolor posoperatorio. Se seleccionaron 120 dientes con diagnósticos que implicaban pulpa vital y con indicación de tratamiento de endodoncia. La preparación biomecánica se llevó a cabo con el sistema ProtaperNext® con lima apical principal X2 o X3. Los dientes se dividieron aleatoriamente de la siguiente forma (n=60): El grupo 1 se obturó con el sistema Guttacore® y el grupo 2 se obturó con una técnica de obturación de cono único y el sistema de obturación Calamus®. Se observó quelas técnicas de obturación termoplástica generaron sobreobturación en 53.33% del total (64 dientes), 56.66% se presentaron en el grupo de obturación con Guttacore® y 50% en el grupo de la técnica con el sistema Calamus®. Se encontró que los dientes anteriores presentaron asociación con la presencia de sobreobturación (p= 0.024) (OR=4.35). De los 120 dientes tratados, 10 (8.33 %) presentaron dolor posoperatorio y sobreobturación radiográficamente visible. La asociación entre la presencia de extrusión de material de obturación y dolor levemoderado fue estadísticamente significativa con un valor p= 0.002. Como conclusión las técnicas de obturación termoplástica en endodoncia Guttacore® y el sistema Calamus® están asociadas significativamente con la probabilidad de extrusión de material obturador y dicha sobreobturación está asociada con dolor posoperatorio, los dientes anteriores presentan 4 veces más riesgo de sobreobturación con las técnicas de obturación utilizadas (AU)

Surgical management with intentional replantation on a tooth with palato-radicular groove.

A palato-radicular groove (PRG) is a developmental anomaly primarily found in the maxillary lateral incisors. It is a potential communication path between the root canal and the periodontium that decreases the survival prognosis of the affected tooth, therefore compromising the stability of the dental structure in the oral cavity. The aim of this case report is to present an original technique where a PRG was treated by means of intracanal disinfection, PRG sealing with glass ionomer, replantation with intentional horizontal 180 degree rotation of the tooth, and an aesthetic veneer placed to provide adequate tooth morphology. The clinical and biological benefits of this novel technique are presented and discussed.

Utilidad de la conformación del túnel liso antes de usar limas rotatorias endodónticas de níquel-titanio / Usefulness of shaping the glide path before using rotary nickel-titanium endodontic files

Introducción: para prevenir la fractura de instrumentos endodonticos actualmente se siguen investigando materiales, técnicas y diseños los cuales buscan reducir su incidencia. La conformación de túnel liso (Glide Path) se ha propuesto con este fin, sin embargo su utilidad ha sido controvertida. Objetivo: comprobar teóricamente mediante la utilización de un análisis de elementos finitos, la utilidad de la conformación de túnel liso, antes de la utilización de limas rotatorias endodonticas de níquel-titanio. Métodos: se realizó una simulación numérica mediante un análisis de elementos finitos, para lo cual se construyeron modelos matemáticos de las limas rotatorias de níquel-titanio S1 y S2 de la serie Protaper®. Con el software Simulation multyphisics de Autodesk® se programaron las propiedades mecánicas de las limas y un límite de falla por fractura de 1270,588 MPa. Posteriormente se aplicó el torque recomendado por el fabricante y se fijo la punta del instrumento (sin conformación de túnel liso) aplicando allí restricciones en todos los grados de libertad.Para simular la realización de la conformación de túnel liso, se aplicaron restricciones en todos los grados de libertad a una determinada distancia de la punta del instrumento, simulando de esta forma que la punta del instrumento permanecía libre. Resultados: al fijar la punta de las limas, los esfuerzos máximos fueron 1545,77 MPa para la S1 y 1306,47 MPa para la S2, observando fractura de los instrumentos. Al fijar las limas a distancia de la punta no se observó fractura. Conclusiones: se demostró teóricamente que al impedir que se atrapen la punta de las limas, se previene su fractura y que dicho atrapamiento se evita con una conformación de túnel liso, por lo que se concluye que este procedimiento es útil para prevenir la fractura de los instrumentos rotatorios de níquel-titanio(AU)

Introduction: materials, techniques and designs continue to be studied with the purpose of reducing the incidence of fracture in endodontic instruments. Shaping of the glide path has been proposed for this end; however, its usefulness has been a matter of controversy. Objective: based on the finite element method, carry out a theoretical analysis of the usefulness of shaping the glide path before using rotary nickel-titanium endodontic files. Methods: numerical simulation was performed based on finite element analysis, to achieve which mathematical models were built of rotary nickel-titanium files S1 and S2 of the Protaper™ series. Autodesk™ Simulation Multiphysics software was used to program the mechanical properties of the files, as well as a fracture failure limit of 1270.588 MPa. The torque recommended by the manufacturer was then applied and the instrument tip fixed into place (without shaping the glide path) with restrictions on all degrees of freedom. In order to simulate glide path shaping, restrictions were applied to all degrees of freedom at a certain distance from the instrument tip, thus simulating that the instrument tip remained free. Results: on fixing the file tips, maximum efforts were 1545.77 Mpa for S1 and 1306.47 Mpa for S2. Instrument fracture was observed. When files were fixed at a distance from the tip, no fracture was observed. Conclusions: it was theoretically demonstrated that when file tips are prevented from being caught, fracture is prevented as well, and such catch is avoided by shaping the glide path. It is therefore concluded that the procedure is useful to prevent the fracture of rotary nickel-titanium instruments(AU)

Theoretical evaluation of Nickel-Titanium Mtwo series rotary files.

Nickel-Titanium rotary files are a technological development that enables dentists to prepare irregularly shaped root canals without altering them. Unfortunately, these files may fracture without any prior visible warning signs. The aim of this study was to perform a theoretical evaluation of the mechanical behaviour of Mtwo Nickel-Titanium rotary files for endodontics, in order to determine which of the files in the basic series are most likely to fracture. Mathematical models of the Mtwo basic file series were analyzed using the finite elements method. Bending and torsion loads were applied to the files both under normal conditions and under extreme conditions, to determine which of them had the highest Von Mises stresses. When the approximation was similar to normal use none of the file models reached the maximum limit of failure by fracture. When used inadequately, file models 10/0.04 and 25/0.06 had the highest Von Mises stresses for bending and torsion, respectively. Thus, it is recommended that Mtwo files 10/0.04 and 25/0.06 should be used once only, to prevent fractures.

A theoretical model of dentinogenesis: dentin and dentinal tubule formation.

INTRODUCTION: Dentinogenesis, odontoblast dentin formation, includes dentinal growth, mineralization and dentinal tubule formation. Odontoblasts synthesize collagen resulting in collagen apposition contributing to dentinogenesis. Furthermore, within the tubule, they express non-collagenous proteins, such as dentin phosphoprotein (DPP), associated with hydroxyapatite crystal formation and growth. The aim of this work was to determine patterns of growth and dentin formation and quantification of its mineralization. Findings from our work are relevant to endodontics for future regenerative treatment. METHODS: We formulated a 3D domain mathematical model, which recreates the events that lead to dentinal tubule mineralization. As reference we used collagen apposition and DPP activity. RESULTS: We obtained a model depicting predentin's mineralization distribution during dentin development. Furthermore, we verified different DPP diffusion coefficients to test the model's sensitivity. CONCLUSIONS: We present a model to shed light on the process of dentin and dentinal tubule formation, and its relation to diffusion and mineralization processes.

Theoretical evaluation of nickel-titanium MTWO series rotary files

Las limas rotatorias de níquel-titanio son un avance tecnológico que permite al odontólogo llevar a cabo tratamientos en conductos con morfologías irregulares Lamentablemente, estos instrumentos pueden fracturarse sin presentar señales visibles que permitan prevenir este accidente. Por lo tantoel objetivo del presente estudio fue evaluar teóricamente el comportamientomecánico de las limas rotatorias de Níquel-Titanio para uso en endodoncia Mtwo® para determinar cuál de losinstrumentos de la serie básica es el que presenta mayor probabilidad de fractura. Con este fin se realizó un análisis por medio del método de los elementos finitos utilizando modelos matemáticos de los instrumentos de la serie básica de las limas Mtwo®. Aestos instrumentos se les aplicaron cargas de flexión y torsión en condiciones normales y en condiciones extremas, para determinar cuáles presentaban los esfuerzos de Von Mises más altos. En una aproximación similar al uso normal, ninguno de los modelosde las limas alcanzó el limite máximo de falla por fractura. Ante un uso inadecuado, los modelos de las limas 10/0.04 y 25/0.06 mostraron los esfuerzos de Von Mises más altos tanto a flexión como a torsión respectivamente, por lo tanto se recomienda dar un solo uso a la lima 10/0.04 y a la lima 25/0.06 de Mtwo® para prevenir la fractura de estos instrumentos.

Nickel-Titanium rotary files are a technological development thatenables dentists to prepare irregularly shaped root canals withoutaltering them. Unfortunately, these files may fracture without anyprior visible warning signs. The aim of this study was to perform atheoretical evaluation of the mechanical behaviour of Mtwo®Nick-el-Titanium rotary files for endodontics, in order to determinewhich of the files in the basic series are most likely to fracture.Mathematical models of the Mtwo®basic file series were analyzedusing the finite elements method. Bending and torsion loads wereapplied to the files both under normal conditions and under extremeconditions, to determine which of them had the highest Von Misesstresses. When the approximation was similar to normal use, noneof the file models reached the maximum limit of failure by fracture.When used inadequately, file models 10/0.04 and 25/0.06 had thehighest Von Mises stresses for bending and torsion, respectively.Thus, it is recommended that Mtwo®files10/0.04 and 25/0.06should be used once only, to prevent fractures.

Theoretical evaluation of Nickel-Titanium Mtwo series rotary files. / Theoretical evaluation of Nickel-Titanium Mtwo series rotary files.

Nickel-Titanium rotary files are a technological development that enables dentists to prepare irregularly shaped root canals without altering them. Unfortunately, these files may fracture without any prior visible warning signs. The aim of this study was to perform a theoretical evaluation of the mechanical behaviour of Mtwo Nickel-Titanium rotary files for endodontics, in order to determine which of the files in the basic series are most likely to fracture. Mathematical models of the Mtwo basic file series were analyzed using the finite elements method. Bending and torsion loads were applied to the files both under normal conditions and under extreme conditions, to determine which of them had the highest Von Mises stresses. When the approximation was similar to normal use none of the file models reached the maximum limit of failure by fracture. When used inadequately, file models 10/0.04 and 25/0.06 had the highest Von Mises stresses for bending and torsion, respectively. Thus, it is recommended that Mtwo files 10/0.04 and 25/0.06 should be used once only, to prevent fractures.

Theoretical evaluation of nickel-titanium MTWO series rotary files

Las limas rotatorias de níquel-titanio son un avance tecnológico que permite al odontólogo llevar a cabo tratamientos en conductos con morfologías irregulares Lamentablemente, estos instrumentos pueden fracturarse sin presentar señales visibles que permitan prevenir este accidente. Por lo tantoel objetivo del presente estudio fue evaluar teóricamente el comportamientomecánico de las limas rotatorias de Níquel-Titanio para uso en endodoncia Mtwo« para determinar cuál de losinstrumentos de la serie básica es el que presenta mayor probabilidad de fractura. Con este fin se realizó un análisis por medio del método de los elementos finitos utilizando modelos matemáticos de los instrumentos de la serie básica de las limas Mtwo«. Aestos instrumentos se les aplicaron cargas de flexión y torsión en condiciones normales y en condiciones extremas, para determinar cuáles presentaban los esfuerzos de Von Mises más altos. En una aproximación similar al uso normal, ninguno de los modelosde las limas alcanzó el limite máximo de falla por fractura. Ante un uso inadecuado, los modelos de las limas 10/0.04 y 25/0.06 mostraron los esfuerzos de Von Mises más altos tanto a flexión como a torsión respectivamente, por lo tanto se recomienda dar un solo uso a la lima 10/0.04 y a la lima 25/0.06 de Mtwo« para prevenir la fractura de estos instrumentos.(AU)

Nickel-Titanium rotary files are a technological development thatenables dentists to prepare irregularly shaped root canals withoutaltering them. Unfortunately, these files may fracture without anyprior visible warning signs. The aim of this study was to perform atheoretical evaluation of the mechanical behaviour of Mtwo«Nick-el-Titanium rotary files for endodontics, in order to determinewhich of the files in the basic series are most likely to fracture.Mathematical models of the Mtwo«basic file series were analyzedusing the finite elements method. Bending and torsion loads wereapplied to the files both under normal conditions and under extremeconditions, to determine which of them had the highest Von Misesstresses. When the approximation was similar to normal use, noneof the file models reached the maximum limit of failure by fracture.When used inadequately, file models 10/0.04 and 25/0.06 had thehighest Von Mises stresses for bending and torsion, respectively.Thus, it is recommended that Mtwo«files10/0.04 and 25/0.06should be used once only, to prevent fractures.(AU)

Does the geometric location of odontoblast differentiation and dentinal tubules depend on a reaction-diffusion system between BMP2 and Noggin? A mathematical model.

INTRODUCTION: The mesenchymal differentiation to odontoblasts is a complex process that determines the formation of dentinal tubules. This process involves a carefully regulated sequence of changes in the behavior of mesenchymal cells coordinated by the expression of different molecular factors that includes mainly the Noggin and bone morphogenetic protein type 2 (BMP2). METHODS: We investigated a bioregulatory mathematic model based on a set of equations of reaction-diffusion to predict the geometry of the formation of the dentinal tubules. RESULTS: We found that odontoblast location and the dentinal tubules formation are determined by the spatial distribution of a set of molecular signals that compete among themselves to maintain places of the greatest concentration of BMP2, which determines the step from mesenchymal cells to odontoblasts and the formation of the dentinal tubules. CONCLUSIONS: This mathematic model suggests a regulatory loop between BMP2 and Noggin, which is highly stable and repeatable and determines the right location patterns of the odontoblasts and the formation of dentinal tubules. This mathematic approach allows us to understand biological phenomena and biochemical activity during the period of pulp differentiation.

Morfogénesis de los túbulos dentinales: un modelo matemático / Morphogenesis of dentinal tubules: a mathematical model

La diferenciación mesenquimal a odontoblasto es un proceso complejo que determina la formación de los túbulos dentinales. Este proceso involucra una cuidadosa y regulada secuencia de cambios en el comportamiento de las células mesenquimales, coordinados por la expresión de diferentes factores moleculares, entre ellos, principalmente, el Noggin y BMP2. En este artículo se simula la formación de los túbulos dentinales a partir de un modelo matemático de reacción difusión que es solucionado por el método de los elementos finitos...

Mesenchymal differentiation into odontoblasts is a complex process determining the formation of dentinal tubules. The process involves a carefully regulated sequence of changes in the behavior of mesenchymal cells, coordinated by the expression of various molecular factors, particularly Noggin and BMP2. In this paper the formation of dentinal tubules is simulated using a reaction-diffusion mathematical model solved by the finite element method...