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1.
Shanghai Kou Qiang Yi Xue ; 29(1): 40-45, 2020 Feb.
Artículo en Chino | MEDLINE | ID: mdl-32524119

RESUMEN

PURPOSE: To study the change of ion precipitation and surface roughness of three dental alloys'coexisting in standard electrolyte solution, in order to provide a reference for the selection of clinical alloy materials. METHODS: Standard samples of Ni-Cr alloy, Co-Cr alloy and Au-Ag-Pd alloy were prepared and divided into 5 groups: Ni-Cr alloy(group N), Co-Cr alloy(group C), Au-Ag-Pd alloy(Group A), Ni-Cr alloy contact with Au-Ag-Pd alloy(group NA), Ni-Cr alloy contact with Co-Cr alloy(group NC). All groups of alloys were soaked in standard electrolyte solution (T=37 ℃, pH=2.31) for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the amount of ions released from each group. The surface morphology of each group was observed and the surface roughness(Ra) was measured using atomic force microscope(AFM). SPSS 18.0 software package was used for statistical analysis. RESULTS: The amount of nickel ions released from group N, NA, NC was (1.32±0.03) µg/cm2, (2.13±0.07) µg/cm2, (1.53±0.08) µg/cm2, respectively. Nickel ions of group NA and NC was significantly more than that of group N(P<0.05), nickel ions of group NA was significantly more than that of group NC(P<0.05). The amount of chromium ions released from group N, NA, NC was (0.06±0.01) µg/cm2, (0.08±0.01) µg/cm2, (0.05±0.01) µg/cm2, respectively, the amount of chromium ions of group NA was significantly more than that of group NC(P<0.05). The surface roughness of Ni-Cr alloy in group N, NA, NC was (4.60±0.16) nm, (5.37±0.08) nm, (5.04±0.15) nm, respectively. The surface roughness of Ni-Cr alloy in group NA and group NC was significantly larger than that in group N (P<0.05). When contact with Au-Ag-Pd alloy or Co-Cr alloy, the amount of nickel ions released and the surface roughness of Ni-Cr alloy both significantly increased. Compared with Co-Cr alloy, Au-Ag-Pd alloy caused Ni-Cr alloy to release more nickel, chromium ions and formed a rougher surface.


Asunto(s)
Aleaciones de Cromo , Aleaciones Dentales , Iones , Ensayo de Materiales , Níquel , Propiedades de Superficie
2.
J Contemp Dent Pract ; 21(4): 351-352, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32584267

RESUMEN

In the last decades, the use of nickel-titanium (Ni-Ti) rotary instruments has become the most effective and popular method among endodontists for shaping root canals, even if there are still concerns regarding the increased risks of intracanal breakage or weakening of the instruments.1,2 So manufacturers started to modify the cross-sectional geometrical aspects of the files in order to improve their resistance to torsional and cyclic fatigue. Design is a major feature in determining instruments' properties including cutting efficiency, removal of debris, stresses generated during instrumentation, and the relative resistance to these stresses; however, a perfect design is not existing and any change in design is likely to provide some advantages but also some disadvantages.3,4.


Asunto(s)
Níquel , Titanio , Estudios Transversales , Aleaciones Dentales , Instrumentos Dentales , Diseño de Equipo , Falla de Equipo , Preparación del Conducto Radicular
3.
West Afr J Med ; 37(3): 253-259, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32476119

RESUMEN

BACKGROUND: Stainless steel crown (SSC) restoration is one of the restorative treatment options in the management of carious primary molars. The Hall technique is a biologic method of managing carious primary teeth by sealing in the caries with SSCs without the routine local anaesthesia and tooth preparations. The objectives of this study was to compare the treatment assessments of the conventional stainless steel crown restoration with Hall technique using subjects' discomfort during treatments and parents' treatment perception, treatment acceptability and satisfaction with the treatment. METHODS: The study was a comparative analytical study involving the placement of 25 SSC restorations using the conventional method and 25 SSC restorations using the Hall technique in 25 subjects aged 3-8 years with a pair or pairs of unrestored enamel or dentinal carious primary molars matched for tooth type, dental arch and extent of caries. Discomfort during the placements of the SSCs was assessed by the subjects while treatment perception, acceptability and satisfaction were assessed by the parents with the use of questionnaires. RESULTS: There was statistically significant difference (p-value 0.00001) between the conventional method and the Hall technique for the discomfort outcomes. There was no statistically significant difference for treatment perception (p=0.73), acceptability (0.72) and satisfaction (0.60). CONCLUSION: The Hall Technique compared favourably well with the conventional method in treatment perception, acceptability and satisfaction but it gave higher level of discomfort in some of the subjects. The Hall Technique appears to be a good method for managing dental caries in primary molar teeth especially in a resource challenged environment where electricity and access to care are contending issues.


Asunto(s)
Coronas , Atención Dental para Niños/métodos , Caries Dental/terapia , Restauración Dental Permanente/métodos , Cementos de Resina/uso terapéutico , Acero Inoxidable , Niño , Preescolar , Aleaciones Dentales , Humanos , Diente Molar/patología , Diente Primario/patología , Resultado del Tratamiento
5.
J Contemp Dent Pract ; 21(1): 1, 2020 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32381792

RESUMEN

Root canal treatment is one of the most challenging practices in dentistry as the complexity and the variability of the endodontic space can often lead the operator to create false trajectories or missing canals. The technical advances in the development of even more efficient and resistant endodontic instrument reached important results in the last few years with the adoption of NiTi alloys and thermal treatments, which could increase the flexibility and the resistance of the instruments.1,2.


Asunto(s)
Endodoncia , Aleaciones , Aleaciones Dentales , Atención Odontológica , Humanos , Tratamiento del Conducto Radicular
6.
J Contemp Dent Pract ; 21(2): 113, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32381811

RESUMEN

The role of nickel-titanium (NiTi) in the production of endodontic instruments increased in the last few decades; therefore, the way of evaluation of its performance increased as well. Nowadays, there are several ways to evaluate NiTi instruments, divided into static and dynamic tests. The static ones are cyclic fatigue tests, torsional resistance tests, flexibility, and cutting efficiency tests. These methodologies have been deeply used to evaluate some of the metallurgical properties of the instruments on the market. Up-to-date, we know very well the behavior of NiTi under static conditions, but these knowledges are too fragmented to be relevant for understanding and evaluating the complexities of intracanal instrumentation. Starting from the purpose to introduce the variable of movement in the testing procedure, some dynamic tests have been proposed, such as dynamic cyclic fatigue test.1,2 Although these kinds of studies were capable of evaluating more precisely the behavior of rotary instruments inside the root canal, they could not take into account, at this moment, the complexities of stresses that instruments undergo during the shaping procedure.3-5 Therefore, some of these tests are not accepted anymore by the scientific community and on the contrary they do not help the general practitioner to orientate in the large amount of rotary instruments present on the market.6 This tends to withdraw the general dentistry from the scientific literature, wearing a groove between the practice and the science.7 Starting from these ideas, in the last couple of years some authors started to think the proper way to real-time evaluation of the performance of NiTi rotary instruments inside the root canal. To do so, a countable and repeatable measurement of instrument's developed stresses was needed. Setzer and Böhme8 first used the torque generated by Revo-S, Vortex, and ProFile to evaluate their performance during instrumentation. The so-called "operative torque" is the summation of torque generated in each point of the instrument during its simultaneous movement around its own axis and up and down inside the canal. The recorded values are influenced by both torsional and flexural stresses, becoming this way a reliable method to analyze, evaluate, and compare the performance of NiTi instruments inside the root canal.9 This methodology is applicable for not only in vitro but also in vivo measurement, as demonstrated by Gambarini et al.10 The main drawback of this kind of evaluation is the not well-determined correlation between the torsional and the flexural stresses; therefore, it is still unpredictable how each influence the other. In conclusion, the potential of real-time torque measurement is wide and still unexplored, but further studies are needed to better understand how torque is developed inside the root canal.


Asunto(s)
Níquel , Titanio , Aleaciones Dentales , Preparación del Conducto Radicular , Torque
7.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 38(2): 160-165, 2020 Apr 01.
Artículo en Chino | MEDLINE | ID: mdl-32314889

RESUMEN

OBJECTIVE: This study aims to compare the efficiency of three kinds of microtube extraction devices, namely, instrument removal system (IRS), micro-retrieve and repair (MR&R) system, and MR&R system using modified microtube in removing separated instruments with different exposure lengths. METHODS: After a cross-section platform model was established, the IRS, MR&R, and MR&R modified microtube system with sidewall window reduced to 0.20 mm were used to retrieve various separated instrument models, and the differences in extraction effects were statistically analyzed by Chi-square test. The separated instrument models were divided into two groups: stainless steel and nickel-titanium instrument groups. In total, 23 instruments were tested for three times each. RESULTS: When the exposed length of separated instrument was 0.50 mm, the removal efficiency of the modified MR&R system group was significantly higher than those of the IRS and MR&R system groups (P<0.001). When the broken end of the fracture instrument was up to 1.00 mm, the success rates of the MR&R system and modified MR&R groups were significantly higher than that of the IRS group (P<0.01). No difference was observed among these three devices when the exposure length of separated instruments was 1.50 mm or higher. CONCLUSIONS: The MR&R and modified MR&R systems have good removal effect when the exposed length of separated instrument is small.


Asunto(s)
Instrumentos Dentales , Preparación del Conducto Radicular , Aleaciones Dentales , Cavidad Pulpar , Diseño de Equipo , Falla de Equipo , Acero Inoxidable , Titanio
8.
Dental Press J Orthod ; 25(1): 64-69, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32215479

RESUMEN

OBJECTIVE: This study proposed to investigate the influence of catastrophizing and others factors related to pain during orthodontic treatment. METHODS: 27 patients with 0.022 x 0.028-in Straight-wire brackets were evaluated during alignment and leveling phase with nickel-titanium wires. Visual Analog Scales measured the intensity of orthodontic pain at six moments after a clinical appointment: 6 first hours; 1, 2, 3, 5, and 7 days. Multiple linear regression and stepwise approach assessed the influence of the following variables on pain: catastrophizing, sex, age, duration of treatment, clinical appointment time (morning or afternoon), and wire diameter. RESULTS: The highest pain intensity was reported 24 hours after activation. These data were used to analyze factors associated with pain level. Age (r = 0.062, p= 0.7586), sex (p= 0.28), catastrophizing (r = -0.268, p= 0.1765), and orthodontic wire diameter (r = 0.0245, p= 0.2181) were not correlated with orthodontic pain in the univariate statistics. Catastrophizing was included in the multiple regression model because it was of great interest. Duration of orthodontic treatment (r = 0.6045, p= 0.0008) and the time when orthodontic appliance was activated (p= 0.0106) showed statistical significant associations with pain, and were also included in the multivariate regression, which showed that about 32% of orthodontic pain could be explained by the duration of treatment (R2= 0.32, p= 0.0475). Catastrophizing (R2= 0.0006, p= 0.8881) and clinical appointment time were not significantly associated with pain (R2= 0.037, p= 0.2710). CONCLUSIONS: Pain after activation of fixed orthodontic appliance is not associated with catastrophizing as well as age, sex, orthodontic wire diameter, and period of activation.


Asunto(s)
Soportes Ortodóncicos , Catastrofización , Aleaciones Dentales , Humanos , Diseño de Aparato Ortodóncico , Alambres para Ortodoncia , Dolor , Titanio
9.
Am J Orthod Dentofacial Orthop ; 157(3): 320-328, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32115110

RESUMEN

INTRODUCTION: This study compared three-dimensional forces delivered to the displaced tooth and its adjacent teeth between passive self-ligation (PSL) and conventional elastic ligation (CL) in simulation of mandibular lateral incisor linguoversions. METHODS: A multisensor system was used to measure three-dimensional forces delivered to brackets attached to the mandibular left central incisor, lateral incisor, and canine (FDI tooth numbers 31, 32, and 33, respectively). Two ligation methods (PSL and CL), 3 nickel-titanium (0.014-inch) archwires similar to the arch form of normal occlusion, and 2 displacements (1 and 4 mm) were tested. RESULTS: In 1-mm displacement, forces were significantly smaller in CL than in PSL at 32 in the labial direction and larger at 31 in the mesial direction for all 3 types of archwires (P <0.01 for both). For 2 of 3 archwires, forces were larger in CL than in PSL at 33 in the lingual direction (P <0.01). In 4-mm displacement, forces were significantly larger in CL than in PSL at 31 in the mesial direction and significantly smaller in CL than in PSL at 33 in the distal direction for all 3 archwires (P <0.05 and P <0.01, respectively). Mean forces in the vertical direction were small, ranging from -0.05 to 0.05 N. CONCLUSIONS: Under a small amount of displacement, force magnitude in PSL was smaller than that in CL at the displaced tooth in labial-lingual directions. Under a large amount of displacement, a more "open coil spring effect" was significantly obtained in CL than PSL at both adjacent teeth of the displaced tooth.


Asunto(s)
Incisivo , Soportes Ortodóncicos , Técnicas de Movimiento Dental , Aleaciones Dentales , Análisis del Estrés Dental , Humanos , Diseño de Aparato Ortodóncico , Alambres para Ortodoncia , Titanio
10.
J Endod ; 46(3): 391-396, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32029265

RESUMEN

INTRODUCTION: Information is scarce regarding current usage practices of nickel-titanium (NiTi) engine-driven instruments in clinical practice. Therefore, the specific purpose of this survey was to assess trends among endodontists regarding the use and reuse of NiTi instruments. METHODS: A 16-question survey was sent by e-mail to about 4000 active members of the American Association of Endodontists. Data were collected over a 6-month period and compared using chi-square tests. RESULTS: A total of 957 surveys were collected (response rate = 23%). Of the respondents, 40.2% worked in solo practices; among them, there were significantly fewer recent graduates (<10 years) compared with those who graduated more than 10 years ago. Furthermore, 41.7% were in a group practice, 4.3% in corporate practice, 10.7% in university settings, and 3% in the military. Overall, 98.3% of respondents reported using NiTi instruments. Respondents who graduated less than 25 years ago use NiTi instruments significantly more (99%) than those who graduated more than 25 years ago (92.6%). Although 22.9% of respondents buy presterilized instruments, 41.6% sterilize them before use, and 35.5% do not sterilize new instruments before use; dental officers in the military reported that they use sterile new instruments in 100% of cases. NiTi instruments were reused by 74% of respondents. The 2 largest segments of the specialist endodontic instrument market belonged to Dentsply (York, PA; 56.9%) and EdgeEndo (Albuquerque, NM; 28.8%). CONCLUSIONS: There are significant differences in the use of NiTi instruments among types of practice and years since graduation. There were noticeable changes compared with findings reported about 10 years ago.


Asunto(s)
Aleaciones Dentales , Instrumentos Dentales , Endodoncistas , Diseño de Equipo , Humanos , Níquel , Pautas de la Práctica en Odontología , Preparación del Conducto Radicular , Encuestas y Cuestionarios , Titanio , Estados Unidos
11.
J Endod ; 46(3): 431-436, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31911005

RESUMEN

INTRODUCTION: The aim of this study was to compare the influences from different access angles and curvature radii on cyclic fatigue resistance of nickel-titanium rotary files. METHODS: Two file systems (2Shape [TS; MicroMega, Besançon, France] and HyFlex CM [HCM; Coltène/Whaledent, Allstätten, Switzerland]) were used. A total of 192 instruments of TS #25/.04 (TS1), TS #25/.06 (TS2), HCM #25/.04, and HCM #25/.06 were evaluated at 3 insertion angles (0°, 10°, and 20°) and 2 radii (5 mm and 3 mm) in 16-mm stainless steel artificial canals with a 60° curvature. Cyclic fatigue resistance was determined by the number of cycles to failure (NCF) using a customized testing device. Data were analyzed statistically with the significance level established at 95%. RESULTS: In the 3-mm radius canal, the instruments showed lower cyclic fatigue resistance than in the 5-mm radius canal (P < .05). HCM #25/.06 and all .04 taper instruments had a significant NCF reduction at 20° and 10° in the 3-mm radius canal (P < .05), whereas TS2 showed no significant differences. In the 5-mm radius of curvature, although .06 taper instruments had no significant NCF reduction for each angle tested, .04 taper files exhibited significant NCF reduction when tested at 20° (P < .05). Comparing the same size instruments, HCM had higher NCF than TS (P < .05). Instruments with a .04 taper exhibited higher NCF than the .06 ones with the same heat treatment (P < .05). CONCLUSIONS: An inclined insertion into the canals decreased cyclic fatigue resistance of thermal-treated instruments with a .04 taper at all radii of curvature tested. The synergistic effect of a small radius of curvature and access angulation of heat-treated instruments decreases their fatigue resistance.


Asunto(s)
Aleaciones Dentales , Instrumentos Dentales , Falla de Equipo , Níquel , Titanio , Cavidad Pulpar , Diseño de Equipo , Ensayo de Materiales , Radio (Anatomía) , Preparación del Conducto Radicular
12.
J Endod ; 46(2): 232-237, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31889584

RESUMEN

INTRODUCTION: Optimum torque reverse (OTR) motion is a torque-sensitive reciprocal motion in which the motor rotates in alternating 90° counterclockwise and 180° clockwise rotation when the torque exceeds a predetermined value. This study aimed to examine whether OTR motion contributes to torque and force reduction during nickel-titanium rotary instrumentation with the crown-down or single-length technique. METHODS: Twenty-eight simulated straight canals in resin blocks were divided into 2 groups according to the type of motion (OTR or continuous rotation). The groups were further subdivided according to the preparation technique (crown-down or single-length technique, n = 7 each). Automated root canal instrumentation was performed with a torque/force analyzing device (300 rpm, up-and-down speed of 10 mm/min) and EndoWave instruments (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) to size #25/0.06 taper. Maximum torque and apical force were recorded and analyzed with analysis of variance and the Bonferroni test. RESULTS: During the crown-down preparation phase (#35/0.08, #30/0.06, #25/0.06, and #20/0.06), OTR motion developed lower maximum torque and upward force (representing the screw-in force) than continuous rotation. During the apical preparation phase (#25/0.06), OTR motion generated significantly lower maximum clockwise and counterclockwise torque (P < .05) when the single-length technique was used and significantly lower maximum upward force regardless of the preparation technique (P < .05) compared with continuous rotation. CONCLUSIONS: Under the present experimental conditions, OTR motion reduced both torque and screw-in force during the crown-down preparation phase of the crown-down technique and during the apical preparation phase of the single-length technique.


Asunto(s)
Cavidad Pulpar , Preparación del Conducto Radicular , Coronas , Aleaciones Dentales , Diseño de Equipo , Rotación , Titanio , Torque
13.
Niger J Clin Pract ; 23(1): 41-45, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31929205

RESUMEN

Objective: This in vitro study aimed to compare the cyclic fatigue resistance of HyFlex EDM (HEDM), Vortex Blue (VB), ProTaper Gold (PG), and OneCurve (OC) nickel-titanium (NiTi) instruments. Materials and Methods: About 12 HEDM (25/.~), 12 VB (25/.06), 12 PG (25/.08), and 12°C (25/.06) instruments were included in this study. All the instruments were tested with a 60° angle of curvature and a 3-mm radius of curvature. All the instruments were utilized until fracture occurred, and then the number of cycles to failure (NCF) was calculated. The data were analyzed statistically using Kruskal-Wallis H and Mann-Whitney U-tests. The statistical significance level was set at P < 0.05. Results: HEDM instruments had the highest cyclic fatigue resistance among all the other instruments (P < 0.05). The OC instruments had a significantly higher fatigue resistance than the PG and VB instruments (P < 0.05); however, there was no significant difference between PG and VB instruments in the NCF (P > 0.05). Conclusion: Within the limitations of this in vitro study, it was found that the cyclic fatigue resistance was higher for the HEDM instruments than for the VB, PG, and OC instruments.


Asunto(s)
Aleaciones Dentales/química , Instrumentos Dentales , Falla de Equipo , Ensayo de Materiales , Preparación del Conducto Radicular/instrumentación , Aleaciones , Diseño de Equipo , Oro , Humanos , Níquel/química , Titanio/química
14.
Dent Mater J ; 39(3): 422-428, 2020 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-31969544

RESUMEN

The aim of this study was to construct a Ti-Nb-Cu ternary phase diagram that plays the role of a map for developing new titanium alloys with excellent machinability and mechanical properties. Fifteen experimental Ti-Nb-Cu ternary alloys composed of Ti-5-30%Nb-2-20%Cu were designed, and ingots made using Ar-arc melting furnace before casting to generate specimen. The alloy castings were evaluated in terms of their microstructures and alloy phases. A Ti-Nb-Ti2Cu pseudo-ternary phase diagram was constructed using X-ray diffractmetry results. Three alloy phases (α-Ti, ß-Ti and Ti2Cu) were established within the specimen. Furthermore, the prescence of two-phase coexistence regions (α+Ti2Cu, α+ß and ß+Ti2Cu), and three-phase coexistence region (α+ß+Ti2Cu) was noted. The findings obtained through microstructural observation corresponded well with the constructed phase diagram.


Asunto(s)
Aleaciones , Titanio , Aleaciones Dentales , Difracción de Rayos X
15.
Dent Mater ; 36(3): 431-441, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31992484

RESUMEN

OBJECTIVE: The Ti-6Al-4V (TAV) alloy is commercially used as a dental implant material. This work seeks to elucidates the origins of degradation of Ti-6Al-4V (TAV) implant alloys that result in peri-implant bone loss. 
Methods: In this work, a combination of microstructure, surface, and solution analyses was utilized to study the corrosion mechanism of the TAV alloy in oral environments. The corrosion of TAV alloys in the F--enriched environment of a crevice was evaluated through nanoscale surface analysis. And, the findings were further rationalized via electrochemical means. 
 RESULTS: Our results suggest the bone loss was caused by crevice corrosion and the consequential release of by-products, and the crevice corrosion was potentially induced by the buildup of corrosive species such as fluorides, which are common additives in dental products. In turn, the corrosion properties of the TAV alloy were evaluated in fluoride enriched environments. Nanoscale analysis of corroded surfaces, carried out using vertical scanning interferometry (VSI) showed that the corrosion susceptibility of the constituent phases dictates the corrosion product species. In specific, the aluminum-rich α phase preferentially dissolves under potential-free conditions and promotes the formation of insoluble Al-Ti oxides. Notably, under conditions of applied potential, oxidative dissolution of the vanadium-rich ß phase is favored, and the vanadium release is promoted. 
 SIGNIFICANCE: These findings elucidate the origins of degradation of TAV-implants that result in the release of corrosion by-products into the local biological environment. More important, they offer guidelines for materials design and improvement to prevent this nature of degradation of dental implants.


Asunto(s)
Implantes Dentales , Aleaciones , Corrosión , Aleaciones Dentales , Ensayo de Materiales , Saliva Artificial , Propiedades de Superficie , Titanio
16.
J Prosthodont ; 29(3): 251-260, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31782584

RESUMEN

PURPOSE: A new type of diazonium-based adhesive has been recently developed by our team to bind dental alloys (Titanium, stainless steel, and cobalt chromium) to dental polymers. Here, we explored the endurance of the resulting adhesive after thermal-cycling and autoclave aging. MATERIALS AND METHODS: Polished samples of titanium (Ti), stainless steel (SS) and cobalt chromium (Co-Cr) were coated with a diazonium-based adhesive. Untreated samples served as controls (n = 12 per each condition). X-ray photoelectron spectroscopy (XPS) was performed to characterize the elemental compositions of the different surfaces. Biocompatibility of the coated alloys was assessed with human gingival fibroblasts (HGF). Inductively coupled plasma (ICP) and total organic carbon (TOC) analyses were used to quantify the ions and organic matters released from the diazonium coated alloys. Endurance of the adhesives was assessed by exposing the samples to autoclaving and thermal-cycling. The tensile strength of the poly(methylmethacrylate) (PMMA)-alloy bond was also tested. RESULTS: Results of mechanical testing demonstrated a higher endurance of the coated CoCr, Ti, and SS compared to the uncoated alloys. The human fibroblasts cultured on the substrates remained alive and metabolically active, and the coatings did not release significant amounts of toxic chemicals in solutions. CONCLUSIONS: The results further support the use of diazonium-based adhesives as new coupling agents for dental applications.


Asunto(s)
Aleaciones Dentales , Cementos Dentales , Aleaciones , Aleaciones de Cromo , Humanos , Ensayo de Materiales , Propiedades de Superficie , Titanio
17.
Aust Endod J ; 46(1): 52-59, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31087492

RESUMEN

This study assessed the cutting properties of two Nickel Titanium file systems with different designs and manufacturing materials. ProTaper Next X1 and X2 (PTN; Dentsply Sirona) and ProTaper Universal S2 and F1 (PTU; Dentsply Sirona) instruments were employed. The cutting parameters, that is torque and apical forces, were determined using a specially designed bench-testing machine. Dimensional and geometric parameters were considered to evaluate the results. The average maximum torque values showed statistically significant differences (P < 0.05) among all instruments. Apical force for PTN X2 and PTU F1 instruments initially decreased and then experienced a rapid increase in the last 2 mm of the canal. For PTN X1 and PTU S2, apical force increased during the entire test. When compared to PTU files, PTN required higher torque and apical forces during the shaping procedure. The results lead us to conclude that PTN instruments demonstrated a lower cutting efficiency than PTU.


Asunto(s)
Aleaciones Dentales , Preparación del Conducto Radicular , Diseño de Equipo , Ensayo de Materiales , Titanio , Torque
18.
Clin Oral Investig ; 24(1): 351-355, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31102046

RESUMEN

OBJECTIVES: The aim of the present study was to determine the effect of taper (.08, .06, and .04) of separated K3XF instruments on duration taken for the secondary fracture formation during ultrasonic activation. MATERIALS AND METHODS: Ten 25/.08 K3XF (SybronEndo, Orange, CA, USA), ten 25/.06 K3XF, and ten 25/.04 K3XF instruments were used for the study. The apical 5 mm of the instruments was cut to simulate the fragments in root canals. Fragments of the instruments were sandwiched between two straight dentin blocks. An ultrasonic tip was used to cause a secondary fracture of the fragment. The time needed for the secondary fracture was recorded for each instrument. The data were statistically analyzed using the Kruskal-Wallis H test (alpha = 0.05). RESULTS: Secondary fractures occurred in all instruments. In the .08 taper group, secondary fractures took longer than in the case of the .06 and the .04 taper groups (P < 0.05). There were no significant differences between the .06 and the .04 taper groups in terms of the time required for the occurrence of a secondary fracture (P > 0.05). CONCLUSIONS: In the .08 taper group, secondary fracture took longer time than in the case of the .06 and the .04 taper groups due to its larger cross-sectional area involved. CLINICAL RELEVANCE: Typically, when removing separated instruments, a much lower power setting is chosen. The purpose of this in vitro study was to determine which tapered files were more resilient to secondary fracture, thus allowing a higher power setting to be chosen. Thus, the results of the present study cannot be used in clinical practice. If the clinician knows the taper of the broken file, the clinician should be very careful with regard to secondary fractures when using ultrasonics to remove the separated smaller tapered instruments.


Asunto(s)
Cavidad Pulpar , Preparación del Conducto Radicular , Ultrasonido , Aleaciones Dentales , Instrumentos Dentales , Diseño de Equipo , Níquel , Titanio
19.
Aust Endod J ; 46(1): 68-72, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31410934

RESUMEN

This study compared the cyclic fatigue resistance (CFR) of three controlled memory (CM) nickel-titanium rotary files (One Curve, EdgeFile and HyFlex CM) in comparison with a file (ProTaper Next) made from M-wire nickel-titanium alloy at two different temperatures (room and intracanal) in an s-shaped canal. One hundred and sixty files were tested to determine the CFR of OneCurve, EdgeFile, HyFlex CM and ProTaper Next in an artificial canal at room and at intracanal temperature. The number of cycles to failure was recorded, and data were analysed. At both temperatures, ProTaper Next exhibited the lowest CFR compared with the other files (P < 0.05). At room temperature, there was no difference among the three CM files regarding CFR (P > 0.05). At intracanal temperature, OneCurve and EdgeFile exhibited more CFR than the HyFlex CM (P < 0.05). Testing at intracanal temperature caused a significant decrease in CFR of all tested files compared with testing at room temperature.


Asunto(s)
Aleaciones Dentales , Preparación del Conducto Radicular , Instrumentos Dentales , Diseño de Equipo , Ensayo de Materiales , Temperatura , Titanio
20.
Dent Mater J ; 39(2): 256-261, 2020 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-31723091

RESUMEN

The artifact volume generated in magnetic resonance (MR) images was quantitatively evaluated to investigate how artifact behavior correlates to the magnetic susceptibility and volume of an implanted metal device. For this, a new low-magnetic-susceptibility Zr-14Nb alloy was compared with two conventional dental alloys, Ti-6Al-7Nb alloy and Co-Cr-Mo alloy, using spherical specimens of each alloy prepared with four different diameters. Then, MR images were recorded under fast spin echo and gradient echo conditions, from which the artifact volume was measured. The artifact volume decreased with the magnetic susceptibility, volume, and mass of the specimens, and significant linear correlations were observed. The artifact volume can be estimated by the equations presented here; nevertheless, further studies are necessary to interpret the influence of some important factors (e.g., imaging conditions, shape, and orientation) to predict the artifact volume more precisely.


Asunto(s)
Aleaciones , Artefactos , Aleaciones Dentales , Imagen por Resonancia Magnética , Magnetismo , Titanio
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