NiTi Instruments Research Articles

Effect of separated instruments on periapical pH using calcium hydroxide as an intracanal medicament in curved root canals

Objective: To evaluate the effect of intracanal separated instruments with different lengths on periapical pH levels using calcium hydroxide (CH) as an intracanal medicament in curved root canals.
 Materials and Methods: 120 teeth (root canal curvature >25˚) were divided into six groups following the root canal preparation. In Group 1, 2 mm and in Group 2, 4 mm NiTi instruments were separated in the apical portion of the root canals and CH paste was applied. In Groups 3 and 4, no separated instrument but CH was applied. In Groups 5 and 6, neither a separated instrument nor CH. The samples were placed inside a glass tubes with distilled water. pH of this distilled water was measured at different time-points.
 Results: At all-time points, pH values between the experimental groups were similar except at 1-day (Group 1 < Group 2, P<0.05). At the 2-day and 30-day time points, Group 3 showed higher pH values than Group 1 (P<0.05). At 7-day and 14-day points, pH values were similar.
 Conclusions: The presence of a separated instrument with different lengths in curved root canals did not have a significant effect on the pH increase caused by CH used as an intracanal medicament.

Current endodontic practice and use of newer technologies in Australia and New Zealand.

This study investigated endodontic clinical preferences, adoption of newer technologies and information sources among dentists and endodontists. Dental and endodontic society members in Australia and New Zealand were surveyed online regarding their endodontic treatment preferences, armamentarium, information sources and continuing professional education (CPE) attendance. Complete responses were received from 71 endodontic specialists or postgraduates (Group E) and 139 general dentists (Group D). Most of Group E used dental operating microscopes (95.8%), endodontic cone-beam computed tomography (CBCT; 98.6%) and calcium silicate-based materials (CSBMs; 97.2%), significantly more (P < 0.001) than Group D (86.3% used loupes, <32% used CBCT for endodontics or CSBMs). Most respondents used dental dam always for endodontics (94.3%), electronic apex locators (EAL; 81.0%) and engine-driven nickel-titanium (NiTi) instruments (91.4%); Group E had more experience with engine-driven NiTi (P < 0.001). Endodontic CPE attendance was highest at dental association programs (P < 0.001) while hands-on NiTi training attendance was highest via commercial companies (P < 0.05). Online information sources were commonly used (38.8% of Group D, 59.2% of Group E). Dental dam, EAL and engine-driven NiTi were almost universally used. The endodontic group reported high adoption of newer endodontic technologies. Endodontic CPE and information sources should be further surveyed as online engagement evolves. © 2023 Australian Dental Association.

A critical evaluation of physical and manufacturing properties of genuine and counterfeit rotary nickel-titanium endodontic instruments.

Rotary nickel-titanium (NiTi) instruments are made to exacting standards and are costly to manufacture, and quality control is paramount. Consequently, unauthorized factories make counterfeit instruments that are less expensive and may therefore be attractive to dentists. Little information exists about the metallurgy and manufacturing quality of such instruments. There is the potential for counterfeit instruments to be at higher risk of fracture during treatment, thereby compromising clinical outcomes. The aim of this study was to evaluate physical and manufacturing properties of genuine and counterfeit ProTaper Next™ and Mtwo® rotary NiTi instruments. This study investigated the metallurgical properties, manufacturing quality, microhardness and number of cycles to failure of two commonly used rotary NiTi systems and compared them with counterfeit products purporting to be genuine articles. Counterfeit instruments were found to be inferior in manufacturing standards and were less resistant to cyclic fatigue when compared to genuine instruments. Counterfeit rotary NiTi instruments may be less efficient at preparing root canals and may be at higher risk of fracture during endodontic treatment. Dentists must be aware that, although less expensive, counterfeit instruments may be of dubious manufacturing quality and at higher risk of fracture if used in patients. © 2023 Australian Dental Association.

A review of the latest developments in rotary NiTi technology and root canal preparation.

The introduction of nickel-titanium (NiTi) mechanical instruments dramatically changed clinical endodontics over the last few decades. Before NiTi, it was necessary to use more instruments to create an ideal root canal shape, and many approaches, sequences and techniques were developed over the years. Recently, NiTi endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments to improve their root canal preparation outcomes and reduce associated canal preparation risks during root canal treatment. Heat treatment is one of the most fundamental approaches to improving the fatigue resistance and flexibility of NiTi endodontic instruments. In addition, new kinematics have been developed to offer greater safety and efficiency. This narrative review describes the general properties and manufacturing of NiTi instruments, and the mechanical system evolution of NiTi instruments.

Dynamic cyclic fatigue resistance of NiTi instruments in a double-curved stainless steel canal with variable distances of displacement

The present study aimed to measure the number of cycles to fracture (NCF) of different instruments using pecking motion at constant and varying distances of movement at body temperature. This study included 20 files from each brand: ProTaper Universal F2, ProTaper Next X2, and WaveOne Gold Primary (Dentsply Sirona, Maillefer, Ballaigues, Switzerland). Instruments from each brand were divided into two groups (ten files for each group) that experienced constant or variable distances in a stainless-steel artificial double-curved canal in a platform that ensured that the instrument rotated at a stable temperature with a minimum fluctuation of the environment. While running, the platform was programmatically controlled to move at any desired distance of instrument displacement to simulate the clinical pecking motion at variable distances. The files were rotated using proprietary programs. The times to fracture were recorded and then transformed into the number of cycles to fracture (NCF). Data were analyzed using Minitab with proper tests. All fragments were observed under a scanning electron microscope to capture and describe the characteristics of the fracture surface. The WaveOne Gold had the highest NCF, while the ProTaper Universal had the lowest NCF. The manufacturer brands and the modes of displacement of the experimental instrument showed interactive effects. The fracture surface revealed no striation. A new design, material, mode of rotation, and different distances of movement have certain effects on the cyclic fatigue resistance of the instrument.

3D Surface Scanning-A Novel Protocol to Characterize Virtual Nickel-Titanium Endodontic Instruments.

The nickel-titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.

Removal of Thermafil Obturators Using 2 Different Techniques: A Comparative Ex Vivo Study

IntroductionThe aim of this ex vivo study was to compare 2 techniques for removal of Thermafil obturators from curved root canals in mandibular molars. MethodsSixty mesial root canals in extracted mandibular molars were distributed into matched pairs according to degree and radius of curvature and were prepared to size 35/.04 and obturated with Thermafil obturators size 35. Each tooth was embedded in resin, mounted in a mannequin head, and isolated with rubber dam to simulate clinical conditions.Removal of obturators was undertaken under a dental operating microscope by an experienced endodontist using either the FragRemover loop device, or reciprocating NiTi instruments. Pre- and postoperative micro-CT scans were taken to compare the amount of remaining filling material and of removed dentin. Eventual problems during removal attempts were recorded. ResultsUsing Reciproc, 24 carriers (80%) were removed, 16 in one piece, 8 in small pieces, and in 6 cases removal failed. The FragRemover removed 12 carriers (40%), all of these completely, but in 18 cases removal failed (P < .05). Reciproc left less remaining filling material than the FragRemover (P < .05) but removed significantly more dentin in the apical part of the root canal (P < .01). There was no significant difference concerning the total amount of removed dentin (P > .05) between both groups.Seven complications occurred in the Reciproc group. In 5 teeth, working length could not be reached; in 2 teeth, a Reciproc file R25 fractured. With the FragRemover, 64 complications occurred, in 36 cases, including second removal attempts, the loop slipped over the carrier, in 24 cases the top of the carrier was sheared off. In 9 cases, separation of the core occurred too far apically, not allowing further use of the FragRemover. In 4 cases, the wire loop tore. ConclusionsReciproc was more effective in removal of Thermafil carriers, whereas when using the FragRemover less dentin was removed in the apical part of the root canal and more obturation material was left.

OUTCOME EVALUATION OF ENDODONTIC TREATMENT WITH PROTAPER ROTARY INSTRUMENT SYSTEM ON MAXILLARY INCISORS

In recent years, thanks to the rapid advancement of science and technology and a better understanding of the anatomy of the root canal system, many new endodontic instruments and materials have been introduced with the desire to minimize complications in the process of preparing the root canal, help the cleaning and shaping process to complete well. It is noteworthy that the emergence of new endodontic files made of Nickel-Titanium alloy (NiTi files), which, according to the recommendations of manufacturers, make the preparation of root canals faster and more efficient, with a much simpler shaping technique than previous stainless-steel files. This is the topic that attracts great interest from clinicians. Therefore, it is necessary to conduct studies to evaluate these types of instruments. Over the years, there has been a lot of research on NiTi instrument systems carried out in the world, which mainly focused on the current types of rotary NiTi files. In Vietnam, although the NiTi instrument system appears a lot on the market and is increasingly employed by many dentists and endodontic experts, the amount of research on them is limited.&#x0D; Therefore, in order to contribute to more understanding and improve the effectiveness of endodontic treatment with niti rotary instrument systems we carry out the research: “Outcome Evaluation of endodontic treatment with Protaper rotary instrument system on maxillary incisors" with two aims:&#x0D; &#x0D; To evaluate root canal sealing results with cone beam computed tomography (CBCT)&#x0D; To evaluate the outcomes of maxillary incisor root canal treatment with the Protaper rotary instrument system.&#x0D;

Opto-magnetic imaging spectroscopy in analyzing rotary NiTi endodontic instruments

Intra-canal fracture of rotary NiTi instruments occurs due to torsional stress, cyclic fatigue, or a combination of these two factors. Broken instruments are a serious obstacle to shaping, cleaning, and filling of the root canal and can adversely affect the outcome of endodontic therapy.The aim of this study was to examine the magnetic properties and ultrastructural changes of new, used, and fractured NiTi instruments using opto-magnetic imaging spectroscopy (OMIS). The study included three sets of different types of rotary instruments: MTwo (VDW, Munich, Germany), Pro Taper Universal (Dentsply Maillefer, Ballaigues, Switzerland), and BioRace (FKG DENTAIRE Swiss Dental Products, Le Crêt-du-Locle Switzerland). Root canal shaping was performed on root canals with different curvatures, and after intra-canal fracture, instruments of the same type (new, used, and fractured) were analyzed using OMIS at the Faculty of Mechanical Engineering, University of Belgrade.The obtained results showed a coincidence of peak localization for the used instruments that did not suffer a fracture, as well as for new, unused instruments of all examined groups. Additionally, there was a coincidence of peak intensities for new and fractured instruments in all groups. The specific treatment of electropolishing of the active surface of BioRace instruments caused a completely different electromagnetic response compared to conventional NiTi sets of tested instruments. New, unused BioRace instruments had the most pronounced positive (5.6078 n.a.u. x1000) and negative (−8.5218 n.a.u. x1000) intensity values.The analysis of NiTi instruments using opto-magnetic imaging spectroscopy indicated changes in the magnetic properties after their instrumentation.

Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments

This study aimed to evaluate the influence of temperature on torsional strength and angular deflection of two experimental NiTi rotary instruments manufactured from Blue and Gold thermal treatments and with identical cross-sections. A total of 40 experimental NiTi instruments 25.06 and with a triangular cross-section and manufactured from Blue and Gold thermal treatments were used (n=20). The torsional test was performed in the 3 mm from the tip of the instrument according to ISO 3630-1. The torsional test evaluated the torsional strength and angular deflection to failure at room temperature (21°C ± 1° C) and body temperature (36°C ±1°C). The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using an unpaired t test for inter and intra-group comparison and the level of significance was set at 5%. The results showed that the body temperature did not affect the torsional strength and angular deflection of the instruments when compared with room temperature (P>0.05). However, at body temperature, the Blue NiTi instruments presented significantly lower angular deflection in comparison with Gold NiTi instruments (P<0.05). There was no significant difference regarding the torsional strength of the instruments at body temperature (P>0.05). The temperature did not affect the torsional strength of the instruments manufactured from Blue and Gold technology. However, the Blue NiTi instruments presented significantly lower angular deflection than Gold instruments at 36°C temperature.

Life span of Neoendo Flex and ProTaper Next rotary files with reciprocating motion in single-rooted teeth.

Cleaning and shaping represent a vital step in the endodontic procedure. In routine endodontic therapy, the fracture of nickel-titanium (NiTi) instruments is a procedural problem creating a major obstacle to therapy. This study examines the life span of one Neoendo Flex and ProTaper Next (PTN) rotary file using reciprocating motion and compares the time required by both file systems for canal preparation. One hundred maxillary permanent central incisors were selected. In that, fifty teeth are utilized in a reciprocating motion (RM) with the PTN file (n = 25) and Neoendo Flex file (n = 25). To check fractured resistance and the overall root canal preparation time, fifty more teeth are employed in continuous motion (CM) with canals prepared using PTN (n = 25) and Neoendo Flex (n = 25). All canals are prepared following the sequence of respective files. Later, the fracture mechanism of the files was inspected using a scanning electron microscope. In an RM motion, both PTN and Neoendo Flex files can be used in a minimum of 25 canals in single-rooted teeth. Statistical analysis using the Mann-Whitney U-test showed no significant difference in total time taken by PTN and Neoendo Flex in both motions. Within the limitation of this study, the RM was found to be better than CM with less incidence of instrument fracture.

CBCT assessment of dentin thickness of lower incisors after shaping with NiTi instruments – in vivo study

Remaining root dentin thickness plays a key role in the longevity of endodontically treated teeth. Purpose: The aim of this study was to compare the root canal wall thickness in the danger zones of mandibular incisors before and after their instrumentation with two different NiTi rotary systems by means of CBCT. Methodology: Thirty lower incisors of patients aged 45 – 55 years underwent primary endodontic treatment with two NiTi files systems: ProTaper Universal and WaveOne Gold. The changes of the root canal thickness in the danger zones of the incisors were investigated by two CBCT scans – one at the beginning of the experiment and the other after the shaping of the root canals. Results: Shaping of the root canals of lower incisors with the two NiTi systems significantly decreased the mesio-distal root dentin thickness in all root canal levels when compared with the baseline values (p≤0.001). NiTi files from both experimental groups removed substantially more root dentin in the coronal portion of the root than in the apical (p&lt;0.05). The intergroup comparison between the two tested NiTi systems revealed no statistically significant difference in their performance at the three observation levels (p&gt;0.05). Conclusions: Both NiTi systems performed equally and removed dentin more aggressively in the coronal portion of the root. Further clinical experiments are necessary to find the minimally invasive endodontic systems for an optimal preservation of root dentin in the danger zones of mandibular inciso

Influence of Coronal Flaring on the Shaping Ability of Two Heat-Treated Nickel-Titanium Endodontic Files: A Micro-Computed Tomographic Study.

Nickel-titanium (NiTi) usage is associated in endodontics with some complications including canal transportation. Centering ability of a NiTi file is the ability to stay centered in the root canal system during instrumentation. Any undesirable deviation from the natural canal path is indicated as canal transportation. A possible strategy to improve the centering ability of NiTi instruments is the pre-enlargement of the coronal third of the root canal to minimize coronal interferences. This procedure is known as coronal flaring. The aim of this study was to perform a micro-computed tomographic (micro-CT) evaluation of the effect of coronal flaring on canal transportation and centering ability of two heat treated nickel-titanium rotary instruments, 2Shape (Micro Mega, Besançon, France) and HyFlex CM (Coltène Whaledent, Altstätten, Switzerland). Thirty extracted mandibular molars with two independent mesial canals were selected and randomly instrumented (n = 15 canals) with One Flare (Micro Mega, Besançon, France) before HyFlex CM, HyFlex CM (without coronal flaring), One Flare before 2Shape and 2Shape (without coronal flaring). One Flare (Micro Mega, Besançon, France) was introduced 4 mm below the canal entrance for canals prepared with coronal flaring. HyFlex CM and 2Shape were used accordingly to manufacturers’ instructions. New files were used for each canal. During and after instrumentation, irrigation procedures were performed. Micro-CT images were obtained pre- and post-preparation to measure and record root canal transportation and centralization. They were reconstructed from root apex to canal orifices, generating approximately 1000 sections per specimen. The anatomical thirds were determined by dividing the number of cross-sectional slices by three. Root canal transportation and centralization were determined by Gambil method, and the mean values were analyzed by repeated measures analysis of variance followed by multiple comparisons of Bonferroni to compare the different instrumentations procedures and the root thirds (p < 0.05). As for root canal transportation, 2Shape reported significantly higher values compared to HyFlex CM in the cervical region independently from the coronal flaring. In the apical region, 2Shape caused significantly minor canal transportation when used with coronal flaring with compared with the absence of coronal flaring. Regarding the centralization, HyFlex CM showed higher values than 2Shape in the cervical, independently from coronal flaring. In the apical region, 2Shape with coronal flaring exhibited significant major centering ratio, compared with not. Within the limitations of this study, coronal flaring reduced canal transportation and improved centralization of the 2Shape files in the apical section while it had no significant influence on shaping ability of the HyFlex CM instruments. Coronal flaring could represent a valid strategy to improve the shaping ability of NiTi files knowing that its benefit could be influenced by the shaping file used.

Endodontic glide path - importance and performance techniques

Glide path is a procedure that precedes mechanical instrumentation of the root canals. It is defined as a procedure used to expand or create a smooth tunnel from the coronal part of the root canal to its physiological terminus. It is performed using small-size hand files or specially designed mechanical NiTi instruments. An adequately created glide path extends the life of rotary NiTi instruments, enables better mechanical and chemical debridement and easier preservation of original morphology of endodontic space during further mechanical instrumentation. Frequent use of mechanical instrumentation in daily practice requires better understanding of the glide path, its significance, and instruments and techniques used for its creation.

Apically extruded debris, canal transportation, and shaping ability of nickel-titanium instruments on contracted endodontic cavities in molar teeth.

Apically extruded debris, canal transportation and shaping ability were compared between contracted endodontic cavities (CECs) and traditional endodontic cavities (TECs) after instrumentation with XP-endo Shaper (XPS), ProTaper Gold (PTG), ProTaper for hand-use (HPT) and Hero Shaper. The CECs or TECs groups were sub-divided into 24 groups according to root canal morphology and nickel-titanium (Ni-Ti) instruments. The weight of apically extruded debris was calculated using the Myers and Montgomery model. Pre- and postoperative images of teeth were scanned using micro-CT and the three-dimensional models were constructed and compared. Under CECs or TECs, XPS and PTG produced less apical debris and formed less canal transportation than HPT and Hero Shaper (P < 0.05). XPS group under CECs extruded less apical debris than that under TCEs for round canals with curvature of 20°-35° (P < 0.05). The centering ratios of four tested instruments were higher under TECs than those under CECs (P < 0.05). The HPT and Hero Shaper had more transportation under CECs than that under TCEs (P < 0.05). No statistical difference was found regarding shaping ability among all the groups. Under CECs, XPS preserves the original root canal anatomy, meanwhile it produces less apical debris than the other instruments.

Formiranje instrumentacione putanje ručnim i mašinskim instrumentima u povijenim kanalima - in vitro studija

Introduction: Preparation of glide path is an important precondition for the safe use of rotary NiTi instruments during endodontic treatment. Aim: The aim of this study was to examine the duration of glide path preparation as well as all the changes in canal morphology and canal diameter after the use of hand K-files and NiTi rotary PathFiles. Material and methods: This research was performed on a total of twenty Endo Training Blocks (Dentsply, Maillefer, Switzerland). The glide path was prepared using hand stainless steel K-files ISO #10-15-20 (Dentsply, Sirona, USA) (n = 10) and NiTi rotary PathFiles ISO #13, #16 and #19 (Dentsply, Sirona, Switzerland) (n = 10). The time required to establish the glide path was measured with an iPhone stopwatch (Apple Inc. Cupertino, California). The images of the apical segment of canals before and after glide path preparation were taken under the stereomicroscope (Boeco BSZ-405, Germany), and then images were analyzed and processed with Scopeimage 9.0 (Teleskop, Austria). Statistical analysis was performed with the Mann-Whitney test at the level of significance 5% (a = 0.05). Results: A statistically significant difference was observed in terms of the time required for glide path preparation. The mean total time for glide path preparation was significantly longer with K-files (382 ± 62 s) than with PathFile (200 ± 11 s) (p &lt; 0.05). A statistically significant difference in terms of changing the morphology of the apical part of the canal (p &gt; 0.05) was not observed. The difference in the diameter of the root canal was at the limit of statistical significance (p ≈ 0.05). Conclusion: Instrumentation with NiTi rotary PathFiles reduces the time required for glide path preparation. Preparing endodontic space for rotary instrumentation with hand K-Files and rotary PathFiles leads to similar changes in the morphology of the apical segment. A slightly larger diameter of the root canal was measured after preparation with the hand K-files.

Effect of various volume syringes on solution delivery time using conventional irrigation technique in 0.04 tapered preparations of single straight root canals

Introduction: The important aspect of endodontic treatment is root canal irrigation. Although agitation systems proved to have enhanced irrigant wall interactions, syringe needle-based delivery systems still play a significant role during the preparatory phases of root canal treatment. The current study aimed to evaluate the time taken for the irrigant delivery during conventional syringe irrigation using different volume syringes in different root canal preparations. Materials and Methods: Two hundred extracted single-rooted premolars with approximately round canals were randomly instrumented to preferred apical preparation sizes using 0.4 tapered Hyflex-CM rotary Ni-Ti instruments and randomly divided as follows: Group I, instrumentation to size 40, 0.04 taper (n = 50); Group II, instrumentation to size 30, 0.04 taper (n = 50); Group III, instrumentation to size 25, 0.04 taper (n = 50); and Group IV, instrumentation to size 20, 0.04 taper (n = 50). Fifty operators were chosen for the experimentation. They were asked to irrigate the prepared specimens using different volume syringes. The entire irrigant delivery time was recorded by a head nurse using a stopwatch, and the values were calibrated and statistically analyzed. Results: Group I recorded significantly lesser time for irrigant delivery during manual syringe needle irrigation (P = 0.005) compared to other groups. Conclusion: Irrigation delivery time was less in 40/0.04 taper preparations, using 1 ml volume syringes.

Comparative evaluation of cleaning efficiency of single file NiTi rotary system during root canal treatment procedure - A scanning electron microscope study.

Optimal biomechanical preparation, thorough irrigation, proper disinfection, and finally, well-sealed obturation is a must to attain definitive success in root canal procedure. Proper preparation of the root canal is all the more imperative to establish a hermetic apical seal with adequately placed filling materials. The present study was conducted for comparing the Cleaning Efficiency of F360 system and the WaveOne Gold (WOG) system of rotary NiTi instrumentation for a root canal. One hundred freshly extracted noncarious mandibular canines were obtained. Access cavity of standard size was made followed by the establishment of working length. Afterward, random division of all the specimens was done into two study groups: group A: the group in which F360 system was used for instrumentation and group B: the group in which the WOG system was used for instrumentation. Irrigations of all the specimens of both the study groups were done followed by root canal shaping by the instrument system of their respective study groups. Scanning electron microscope (SEM) was used for assessment after specimens were cut buccolingually. Debris score and residual smear layer score were used for assessment. Among group A specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.76, 2.39, and 2.65, respectively. Among group B specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.34, 1.59, and 1.92, respectively. While analyzing statistically, it was seen that the mean smear layer score was significantly higher among specimens of group A in comparison to group B. While analyzing statistically, it was seen that the mean debris score was significantly higher among specimens of group A in comparison to group B. The cleaning effectiveness of WOG instruments was significantly enhanced in comparison to F360 equipment.

A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature.

To develop a model to test cyclic fatigue resistance of TruNatomy instruments undergoing rotational and axial movement at body temperature. A total of 288 Prime and Medium instruments were subjected to cyclic fatigue testing in simulated canals (at 37°C) using a model with either rotational movement only or rotational and axial movement simultaneously. Two different sized canals and three different types of curvatures were tested for each instrument (30/0.04 and 30/0.06 for Prime; 38/0.04 and 40/0.06 for Medium). The number of cycles to failure (fatigue resistance) was recorded. Rotational and axial movement of instruments led to greater fatigue resistance compared with rotational movement alone. Apical curvatures led to greater fatigue resistance than curvatures in the coronal and middle third. The developed dynamic model at body temperature to evaluate fatigue resistance of instrument closer simulates clinical scenarios.

Management of Separated Endodontic Instrument and a Blocked Canal - A Case Report

The fracture of endodontic instruments and canal blockage is a procedural problem creating a major obstacle to normal routine endodontic therapy. The separated instrument, particularly a broken file, leads to metallic obstruction in the root canal while canal blockage,caused by packing dentin chips and/or tissue debris, impedes efficient cleaning and shaping. Negotiating the canal and achieving patency is a must but when attempts fail to bypass such a fragment or gaining patency becomes difficult, it should be achieved by newer techniques and equipments. Dental operating microscope and ultrasonics have found indispensable applications in a number of dental procedures. This clinical casedemonstrates the usage of anultrasonic device under operative microscope in the removal of separated NiTi instrument and achieving patency in symptomatic premolars.