Influencia de los factores relacionados con la fatiga cíclica de las limas endodónticas de NiTi

Tesis por compendio de publicaciones[EN] The endodontic rotary and reciprocating files of NiTi has reported to exhibit unexpected fractures inside the root canal system during the root canal treatment; which can affect the prognosis of the endodontic therapy. Therefore, it is important to assess the variables related to this intraoperative complication. Aim: To analyze the influence of the variables related to cyclic fatigue on the fracture resistance of NiTi endodontic instruments. To analyze the influence of the apical diameter and taper of NiTi rotary endodontic instruments on their resistance to cyclic fatigue. To analyze the influence of cross-sectional design and pitch on the mechanical behavior of NiTi endodontic instruments under bending and torsional conditions. To analyze the influence of the cross-sectional design of NiTi rotary endodontic instruments on the resistance to cyclic fatigue. To analyze the influence of the NiTi alloy of endodontic rotary instruments on the resistance to cyclic fatigue. To analyze the influence of the pecking motion frequency of NiTi rotary endodontic instruments on their resistance to cyclic fatigue. To analyze the influence of the movement of NiTi rotary and reciprocating endodontic instruments on their resistance to cyclic fatigue. To analyze the influence of reciprocating movements of NiTi alloy endodontic reciprocating instruments on their resistance to cyclic fatigue. To analyze the influence of the number of uses and sterilization cycles of NiTi alloy endodontic reciprocating instruments on their resistance to cyclic fatigue. To analyze the resistance to cyclic fatigue of new NiTi endodontic systems. To analyze the influence of the radius and angle of curvature of the root canal system on the mechanical behavior of NiTi endodontic instruments. To analyze the volumetric wear of NiTi endodontic reciprocating instruments subjected to cyclic fatigue. To analyze the removal capacity of separated NiTi alloy endodontic rotary instruments within the root canal system and the wear of root dentin Materials and Methods: In vitro and finite element methods were performed for analyzing the variables related to the cyclic fatigue. Results: Statistical analisys were performed in order to assess the statistical significant differences among the parameters of each variable. Conclusions: The variables analized influences on the resistance of the NiTi alloy endodontic instruments to cyclic fatigue. The increased apical diameter and taper of NiTi endodontic rotary files decreased their resistance to cyclic fatigue. The use of files with a triangular-shaped cross-section and a small pitch are recommended in order to minimize ledging and maximize fatigue life. The double S-shaped cross-section of NiTi alloy endodontic files shows higher cyclic fatigue resistance than the rectangular cross-section, the convex triangular cross-section, and the triangular cross-section of NiTi alloy endodontic files. The NiTi CM-Gold wire alloy of the ProTaper Gold endodontic rotary files resulted in greater resistance to cyclic fatigue than ProFile Vortex Blue, ProTaper Next, and ProTaper Universal endodontic rotary files A low frequency of pecking motion is recommended to reduce the risk of failure of endodontic rotary files associated with cyclic fatigue. NiTi alloy endodontic rotary files using reciprocating movement at 350 rpm with 120° counterclockwise and 30° clockwise motion exhibit greater resistance to dynamic cyclic fatigue than files used with a reciprocating movement at 400 rpm with 120° counterclockwise and 30° clockwise motion, continuous rotational speed at 200 rpm, continuous rotational speed at 350 rpm, or continuous rotational speed at 500 rpm; it is therefore advisable to use reciprocating movements at a low speed. The ReFlex Smart reciprocating movement increased the cyclic fatigue resistance of endodontic reciprocating files compared with traditional reciprocating movement. The time of use of NiTi endodontic reciprocating files negatively afects dynamic cyclic fatigue resistance; however, dynamic cyclic resistance is not afected by the number of sterilization cycles. Smarttrack NiTi alloy endodontic reciprocating files display greater resistance to cyclic fatigue than Endogal and Path Max Pro NiTi alloy endodontic rotary files, due to the reciprocating movement and metallurgical composition. Significant influence of the root canal geometry on the fatigue life of the NiTi rotary files and reveal the higher importance of the radius of curvature with respect to the angle of curvature of the root canal. The CM-wire NiTi alloy endodontic reciprocating files exhibit a volumen wear after clinical use. Ultrasonic tips enable greater ease of removal of NiTi endodontic rotary files from the root canal system, with similar amounts of dentin removal between the two methods

Applications of CBCT in Endodontics

There are many articles published in recent years on the use of CBCT in endodontics and this diagnostic technique is increasingly required in order to have a more accurate prognosis of the teeth to be treated. The purpose of this chapter is to discuss the use of Conical Beam Computed Tomography (CBCT) in the field of endodontics. This issue is controversial at the moment because of the increase in the radiation to which patients are being subjected; however, we know that sometimes the X-rays taken with different angles in relation to some teeth depending on the different cases are incompatible in form and density, which does not allow us to make an exact diagnosis. The use of CBCT would have provided an image of greater diagnostic value in those cases. In addition, the use guidelines published by the American Endodontics Association and the American Radiology Association jointly mark the way forward and the use we can give the CBCT for the diagnosis of complex cases

A comparison of the marginal adaptation of composite overlays fabricated with silicone and an intraoral scanner

Intraoral scanners have been developing during last years. The aim of this study was to know if digital impressions achieve a marginal adaptation in overlays as well as conventional impressions with silicone. Sixty-two extracted molars were selected. Th

Novel Digital Technique to Quantify the Area and Volume of Cement Remaining and Enamel Removed after Fixed Multibracket Appliance Therapy Debonding: An In Vitro Study

The aim of this study was to construct a novel, repeatable, reproducible, and accurate measurement protocol for the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere fixed multibracket appliances. A total of 30 brackets were cemented and removed with over 30 extracted teeth embedded into three experimental models of epoxy resin. The models were scanned before and after bracket placement, bracket debonding, and polishing the remaining cement. The brackets were submitted to micro-computed tomography. The standard tessellation language digital files were aligned, segmented, and re-aligned using geomorphometric software. The digital measurement technique accuracy, repeatability, and reproducibility were analyzed using Gage R&R statistical analysis. The variability attributable to the area and volume measurement techniques of the total variability of the samples was 0.70% and 0.11% for repeatability, respectively, and 0.79% and 0.01% for reproducibility, respectively. The re-alignment procedure is a repeatable, reproducible, and accurate technique that can be used to measure the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere the fixed multibracket appliance.Odontologí

Computerized Generation and Finite Element Stress Analysis of Endodontic Rotary File

Introduction: The finite element method has been extensively used to analyze the mechanical behavior of endodontic rotary files under bending and torsional conditions. This methodology requires elevated computer-aided design skills to reproduce the geometry of the endodontic file, and also mathematical knowledge to perform the finite element analysis. In this study, an automated procedure is proposed for the computerized generation and finite element analysis of endodontic rotary files under bending and torsional conditions. Methods: An endodontic rotary file with a 25mm total length, 0.25mm at the tip, 1.20mm at 16mm from the tip, 2mm pitch and squared cross section was generated using the proposed procedure and submitted for analysis under bending and torsional conditions by clamping the last 3mm of the endodontic rotary file and applying a transverse load of 0.1N and a torsional moment of 0.3N⋅cm. Results: The results of the finite element analyses showed a maximum von Mises stress of 398MPa resulting from the bending analysis and a maximum von Mises stress of 843MPa resulting from the torsional analysis, both of which are next to the encastre point. Conclusions: The automated procedure allows an accurate description of the geometry of the endodontic file to be obtained based on its design parameters as well as a finite element model of the endodontic file from the previously generated geometry

Digital technique to analyze the wear of the slot after orthodontic treatment through fixed multibracket appliances

Introduction To assess the accuracy, repeatability and reproducibility of a measurement digital technique to quantify the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment with the previous measurement traditional technique (scanning electronic microscope (SEM)). Methods A total of 100 fixed multibracket appliances were cemented during the 15 months orthodontic treatment and subsequently removed. The fixed multibracket appliances were submitted preoperatively and postoperatively to a micro-computed tomography (micro-CT) scan to obtain accurate standard tessellation language (STL) digital files of the fixed multibracket appliances and to a preoperatively and postoperatively SEM analysis. Afterwards, pre-operatively and postoperatively STL digital files of each fixed multibracket appliances were aligned using morphometric software with the best fit algorithm. Subsequently, area and volume wear of fixed multibracket appliances was identified, isolated and measured. Results The repeatability and reproducibility of the digital measurement method for the area ( mm2) and volume ( mm3) were analyzed by Gage R&R statistical analysis. The area wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 3.7% and a reproducibility of 0%. The volume of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 0.9% and a reproducibility of 5.6%. However, the traditional measurement technique showed a repeatability of 0.58% and a reproducibility of 33.01%; hence, it was repeatable but not reproducible. Conclusions The digital measurement technique is a reproducible, repeatable, and accurate method for quantifying the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment.Odontologí

Update and Making-Decisions in Dental Traumatology

Dental traumatology is highlighted as an unexpected emergency event which can occur at any moment, age, sex, and gender. Crown fractures account for most traumatic injuries occurring in the permanent dentition. A complete radiographic examination is considered essential in order to assess the state of the pulp, the degree of root development, and the existence of any pathologies affecting the supporting tissues. These examinations also provide a useful tool for subsequent comparisons with those conducted after treatment, ensuring adequate clinical follow-up. Additionally, avulsion of permanent teeth has been highlighted as one of the most relevant dental injuries; therefore, the prognosis of this traumatic event has been directly related to the treatment decision-making process and the time passed since the accident. In addition, dental trauma is also one of the most frequent emergency situations seen in Pediatric Dentistry; moreover, the dental injury of the temporary teeth could also affect to the permanent teeth; hence, it is necessary to perform an exhaustive clinical and radio diagnostic exam to allow a correct diagnosis and a predictable treatment plan. Therefore, the creation of action protocols makes it possible to simplify and facilitate decision-making under stressful situations for patients and clinicians

A reproducible and repeatable digital method for quantifying nasal and sinus airway changes following suture palatine expansion

[EN] Purpose The airway complex is modifed by palatine expansion. Computer tomography has been used in the past to determine the change in volume, but there was a lack of a specifc, reproducible method for this purpose. The present study sought to determine the accuracy, reproducibility, and repeatability of an innovative digital measurement technique for analyzing the volume of maxillary and nasal sinus airways following suture palatine expansion performed with the Hyrax disyuntor appliance.Methods Patients underwent preoperative and postoperative cone-beam computed tomography (CBCT) scans. The datasets were subsequently uploaded into a digital treatment planning software to record the volume of the right and left maxillary sinus, as well as the nasal and maxillary sinus airway complex. The Gage Repeatability & Reproducibility statistical analysis methodology was used to evaluate the repeatability and reproducibility of this measurement technique when measuring the volume of maxillary and nasal sinus airways following suture palatine expansion with the Hyrax disyuntor appliance. Additionally, comparative analysis between preoperative and postoperative measures was performed using Student’s t-test for statistical analysis.Results In 5 patients, paired t-tests found statistically signifcant diferences before and after treatment in the volumes of the left maxillary sinus (p=0.002), right maxillary sinus (p=0.001), and nasal and maxillary sinus airway complex (p=0.005) after suture palatine expansion with the Hyrax disyuntor appliance. Conclusion The proposed digital technique is an accurate, repeatable, and reproducible measurement technique for analyzing the volume of maxillary and nasal sinus airways following suture palatine expansion using the Hyrax disyuntor.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

What can we do with a dental avulsion? A multidisciplinary Clinical Protocol

The aim of this case report was to explain a multidisciplinary and conservative approach carrying out the replantation of an avulsed closed apex central incisor stored in dry conditions for a 16-hour period from the moment of trauma. This report describes a case of a 28 year-old male who suffered contusion of the upper lip, avulsion of right upper central incisor, enamel cracks after trauma of left upper central incisor and upper left lateral incisor crown fracture due to an accident. Avulsed tooth was dry stored and it was replanted 16h after the trauma. The root was disinfected and the necrotic periodontal tissue removed, the endodontic treatment was done before replantation and a flexible splint was applied to tooth 13 to tooth 23. Two months later a contralateral tooth presented crown discoloration occurred due to pulp necrosis an endodontic treatment as well as bleaching were carried out. An esthetic restoration for lateral incisor crown fracture was also done. In the one year review the patient remains asymptomatic, with no signs of root resorption or ankylosis of the damaged teeth. A conservative approach of tooth with delayed reimplantation can be a stable and functional with the appropriate treatment procedures. A clinical protocol for patients and professionals for the treatment of the avulsed tooth is proposed

Comparative Study of the SEM Evaluation, EDX Assessment, Morphometric Analysis, and Cyclic Fatigue Resistance of Three Novel Brands of NiTi Alloy Endodontic Files

In this study, we compare and analyze the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), morphometry and cyclic fatigue resistance of Endogal, PathMax, and Smarttrack novel brands of nickel–titanium (NiTi) alloy endodontic files. Material and Methods: Thirty sterile NiTi endodontic rotary files were randomly selected and assigned to one of the following study groups: A: 25.08 F2 Endogal (EDG) (n = 10); B: 25.08 F2 Path Max Pro (PMP) (n = 10); and C: 25.06 Smarttrack (ST) (n = 10). Dynamic cyclic fatigue tests were conducted using a cyclic fatigue device in stainless steel artificial root canal systems with an apical diameter of 250 µm, curvature angle of 60°, radius of curvature of 3 mm, and taper of 6%. Additionally, we analyzed the NiTi endodontic rotary files using EDX, SEM, and morphometry after micro-CT scanning. The results were analyzed using Weibull statistical analysis and ANOVA testing. Results: SEM, EDX, and morphometric analyses showed differences between the three novel brands of NiTi endodontic rotary files. Moreover, statistically significant differences were observed between the number of cycles to failure and time to failure of the three novel brands of NiTi endodontic rotary files (p < 0.001). Conclusions: Smarttrack NiTi alloy endodontic reciprocating files display greater resistance to cyclic fatigue than Endogal and Path Max Pro NiTi alloy endodontic rotary files, due to the reciprocating movement and metallurgical composition