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

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

An analysis in vivo of intracanal bacterial load before and after chemo-mechanical preparation: a comparative analysis of two irrigants and two activation techniques

Background: The goals of this randomized double-blind trial were to assess the antimicrobial activity in vivo of Sodium hypochlorite (NaOCl) vs. chlorhexidine gluconate (CHX) used in combination either with EndoActivator® or IRRI S® files in patients with apical periodontitis. Material and Methods: A total of 120 patients with apical periodontitis (in single or multiple root canals) were randomly assigned to the four irrigation protocols outlined below: Group A: 5.25% sodium hypochlorite (NaOCl) + EndoActivator®; Group B: 5.25% NaOCl + IRRI S® files; Group C: 2% chlorhexidine gluconate (CHX) + EndoActivator®; Group D: 2% CHX + IRRI S® files. Paper points were used to collect microbiological samples before (1A samples) and after (1B samples) irrigation. Viable colony-forming units (CFU) were quantified twice: (1) without speciation, and (2) only for Enterococcus Faecalis ( EF ). Statistical analysis was performed using SPSS 22.0 for Windows. Results: No significant differences were observed between NaOCl and CHX in the reduction of CFU; in fact, reduction was > 93% for the two irrigants. Conversely, statistically significant differences were found between the two activation techniques (sonic and ultrasonic) in the reduction of Enterococcus faecalis ( EF ). Thus, the effectiveness of ultrasonic activation was significantly higher (> 93%; p=0.012) as compared to sonic activation. Following the combination of the two irrigants with the two activation techniques (groups A, B, C and D), significant differences were observed between group A and B ( p =0.025) in the reduction of EF populations, reaching up to 94%. Conclusions: NaClO and CHX are effective in reducing intracanal bacterial load. Ultrasonic activation is the most effective activation technique in reducing EF populations

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

Computerized Generation and Finite Element Stress Analysis of Endodontic Rotary Files

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

Endodontic re-treatment and restorative treatment of a dens invaginatus type II through new technologies

Background: The complex anatomy of dens invaginatus makes access cavity to root canal system difficult, which has an impact on the prognosis of these teeth. A novel technique, based on new technologies, is proposed to make access cavity conservative and guided with minimal dental structure lost. Material and Methods: This case report shows the root canal retreatment and the endodontic surgery of a dens invaginatus type II in a left lateral upper incisor previously treated which was affected by a chronic apical abscess and an apical fracture. A Cone Beam Computed Tomography was performed to better diagnosis the dental anatomy. An intraoral scan was performed to get a digital 3D model. A computer-guided implant planning software was used to plan the access cavity and design the splint guided. Finally, the clinical crown was restored by a resin nanoceramic veneer made by a chairside system made up of an intraoral scanning unit and a grinding unit. Last, the authors carried through the endodontic surgery to extract the apical fractured fragment. Results: Follow-up appointments at 6, 12 and 18 months showed a radiographic reduction of the periapical lesion and absence of clinical signs. Conclusions: The splint guide allowed a guided and conservative access cavity to root canal system. It facilitates the root canal retreatment and improves the prognosis of the teeth with dental malformations

Influence of the Pecking Motion Frequency on the Cyclic Fatigue Resistance of Endodontic Rotary Files

Purpose: To analyze the influence of the pecking motion frequency on the cyclic fatigue resistance of endodontic rotary files. Material and Methods: Sixty PlexV 25.06 endodontic rotary files were selected and distributed into three groups: 30 movements/min (n = 20), 60 movements/min (n = 20), and 120 movements/min (n = 20). A dynamic cyclic fatigue device was designed using Computer Aided Design/ Computer Aided Engineering (CAD/CAE) technology and manufactured by 3D impressions to simulate the pecking motion performed by an operator. Failures of the endodontic rotary files were detected by a Light-Emitting Diode (LED)/Light-Dependent Resistor (LDR) system controlled by an Arduino-Driver complex and management software. Endodontic rotary files were tested on an artificial root canal manufactured by wire electrical discharge machining (EDM), with similar dimensions to those of the instrument under examination. Endodontic rotary files were used following the manufacturer's recommendations. The results were analyzed by ANOVA and Weibull statistics. Results: All pairwise comparisons revealed statistically significant differences in all three variables, except for the difference in the number of cycles between the groups with 60 and 120 movements/min (p = 0.298). The scale distribution parameter of Weibull statistics showed statistically significant differences in all three variables, except for the differences in the number of cycles between groups with 30 and 60 movements/min (p = 0.0722). No statistically significant differences in the three variables were observed for the shape distribution parameter. Conclusion: A low frequency of pecking motion is recommended to reduce the risk of failure of endodontic rotary files associated with cyclic fatigue