scholarly journals Do NiTi Instruments show Defects before Separation? Defects caused by Torsional Fatigue in Hand and Rotary Nickel-Titanium (NiTi) Instruments which Lead to Failure during Clinical Use

2012 ◽  
Vol 13 (6) ◽  
pp. 867-872 ◽  
Author(s):  
Sudhir Kumar ◽  
P Ratnakar ◽  
NV Murali Krishna Chakka ◽  
Sanjib Das ◽  
Anandamy Bagchi ◽  
...  
Keyword(s):  
Nickel Titanium ◽  
Clinical Use ◽  
New Classification ◽  
Torsional Fatigue ◽  
Anterior Teeth ◽  
Microscopic Evaluation ◽  
Different Types ◽  
Before And After ◽  
The Difference ◽  
Niti Instruments

ABSTRACT Aims Visual and microscopic evaluation of defects caused by torsional fatigue in hand and rotary nickel titanium (NiTi) instruments. Materials and methods Ninety-six NiTi greater taper instruments which were routinely used for root canal treatment only in anterior teeth were selected for the study. The files taken include ProTaper for hand use, ProTaper Rotary files and Endowave rotary files. After every use, the files were observed visually and microscopically (Stereomicroscope at 10×) to evaluate the defects caused by torsional fatigue. Scoring was given according to a new classification formulated which gives an indication of the severity of the defect or damage. Statistical analysis Data was statistically analyzed using KruskallWallis and Mann-Whitney U test. Results Number of files showing defects were more under stereomicroscope than visual examination. But, the difference in the evaluation methods was not statistically significant. The different types of defects observed were bent instrument, straightening/stretching of twist contour and partial reverse twisting. Endowave files showed maximum number of defects followed by ProTaper for hand use and least in ProTaper Rotary. Conclusion Visible defects due to torsional fatigue do occur in NiTi instruments after clinical use. Both visual and microscopic examinations were efficient in detecting defects caused due to torsional fatigue. This study emphasizes that all files should be observed for any visible defects before and after every instrumentation cycle to minimize the risk of instrument separation and failure of endodontic therapy. How to cite this article Chakka NVMK, Ratnakar P, Das S, Bagchi A, Kumar S, Anumula L. Do NiTi Instruments show Defects before Separation? Defects caused by Torsional Fatigue in Hand and Rotary Nickel-Titanium (NiTi) Instruments which Lead to Failure during Clinical Use. J Contemp Dent Pract 2012;13(6):867-872.

scholarly journals The effect of orthodontic clinical use on the mechanical characteristics of nickel-titanium closed-coil springs

2019 ◽  
Vol 47 (2) ◽  
pp. 803-814 ◽  
Author(s):  
Haixia Geng ◽  
Hongli Su ◽  
John Whitley ◽  
Feng-Chang Lin ◽  
Xin Xu ◽  
...  
Keyword(s):  
Mechanical Characteristics ◽  
Tooth Movement ◽  
Heat Treating ◽  
Nickel Titanium ◽  
Time Dependent ◽  
Clinical Use ◽  
Heat Treated ◽  
Testing Data ◽  
Before And After ◽  
Force Activation

Objective To examine the effect of clinical use on both force retention and the deactivation of closed-coil nickel-titanium (NiTi) springs in a 16-week trial. Methods The force-activation curves for NiTi springs were determined before and after clinical use. The rate of tooth movement and maximum force (MF), hysteresis between activation and deactivation, and mean force of the deactivation plateau (MDF) were examined and correlated as a function of 4, 8, 12 and 16 weeks of clinical use. To recover the force properties, the springs were heat treated at 100°C and the results were compared with the preceding data. Results A total of 36 springs were analysed. The MF loss after use was 60, 74, 55, and 48 g for the 4-, 8-, 12- and 16-week springs, respectively. Heat treating had little effect on the MF. Clinical use lowered hysteresis by a mean of 180 g*mm compared with the pre-clinical use data, and heat treating increased the hysteresis by a mean of 59 g*mm above the post clinic testing data. The MDF was nominally 100 g less than the MF. Teeth moved approximately 1 mm/month, independent of the force loss. Conclusions The loss of MF and the lowering of the MDF was not time dependent. Heat treating can partially recover the mechanical properties of the used springs.

scholarly journals Study on the Cure Rate of Invisible Headgear Orthodontic Opening Deep Occlusion of Anterior Teeth

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Longfeng Wang
Keyword(s):  
Orthodontic Treatment ◽  
Root Resorption ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Cure Rate ◽  
Anterior Teeth ◽  
Before And After ◽  
The Difference

Objective: To explore the cure rate of bracketless invisible headgear orthodontic for opening deep occlusion of anterior teeth. Methods: 10 cases with deep occlusion of anterior teeth were selected. All of the patients were admitted to our hospital from January 2017 to January 2020. All selected patients received bracketless invisible headgear orthodontic treatment. We took CBCT (cone beam CT) before and after orthodontics) lateral cranial radiographs and curved tomographic radiographs to analyze the effect of orthodontic treatment in 10 patients. Results: The changes of 10 patients before and after the orthodontic treatment were not significant in U1-SN, U6-SN, MP-FH (P>0.05); the U1-PP of the patients all decreased by 3~5mm. Compared with the effect before orthodontic treatment, the difference is significance(P<0.05); The tooth loosening didn’t occur obviously in 10 patients. And 2 patients (20.00%) had mild root resorption in the anterior teeth. Conclusion: The effect of invisible headgear orthodontic treatment without brackets is significant in orthodontic treatment of patients with deep occlusion of anterior teeth. The pressure of the upper anterior teeth can reach as low as 3~5mm. The cure rate of deep occlusion of open anterior teeth is high. The orthodontic method is comfortable, with beautiful appearance, which is easier to be accepted by patients.

scholarly journals Comparing Meal Satisfaction Based on Different Types of Tableware: An Experimental Study of Japanese Cuisine Culture

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1546
Author(s):  
Tomoko Hasegawa ◽  
Nobuyuki Sakai
Keyword(s):  
Food Industry ◽  
The Other ◽  
Food Preparation ◽  
Japanese Culture ◽  
Japanese People ◽  
Perceptual Evaluation ◽  
Different Types ◽  
Before And After ◽  
The Difference ◽  
Plastic Containers

In Japan, as in other countries, the externalization of food preparation is increasing. Japanese people are interested in the combination of food and tableware and they are concerned about transferring ready-made meals from plastic containers to natural tableware. This study aimed to examine the varying evaluations of meals due to differences in tableware. In this study, we investigated the effect of tableware on meal satisfaction, which is emphasized in Japanese culture. We studied the difference in the evaluation of ready-made meals (a rice ball, salad, croquette, and corn soup) before, during, and after a meal under two conditions: plastic tableware and natural wooden tableware. The results showed that there was no difference in the perceptual evaluation of taste and texture during the meal, except for the color of the salad and the temperature of the soup. On the other hand, meals served on natural wooden tableware were rated more positively than those served on plastic tableware before and after meals. These results suggest that, in Japan, the use of tableware, even for ready-made meals, increases the level of meal satisfaction. These findings have implications for both the providers and consumers of ready-made meals as well as the food industry.

scholarly journals Differential scanning calorimetric investigations of three rotary nickel-titanium instrument systems before and after simulated clinical uses

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Khoa Van Pham
Keyword(s):  
Human Body ◽  
Clinical Performance ◽  
Clinical Situation ◽  
Nickel Titanium ◽  
Differential Scanning Calorimetric ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Significant Difference ◽  
Before And After ◽  
Niti Instruments

Abstract Background The transformation temperatures were important values, influencing the mechanical properties and clinical performance of nickel-titanium instruments. The aim of this study was to determine the transformation temperatures of three rotary nickel-titanium (NiTi) instruments: Reciproc, HyFlex CM Pro, and Neoniti before and after simulated clinical uses. Methods Ninety new NiTi instruments of three single-file instruments: Reciproc, HyFlex CM Pro, and Neoniti were divided into three groups. Thirty instruments of each group were divided into 3 subgroups (10 instruments for each subgroup): new, one-time simulated clinical used and sterilised, and three times simulated clinical used and sterilized subgroups. The instruments were in the as-received condition for the new subgroups, one time used in the plastic endo-training blocks and sterilised for the one-time subgroups, and three times used in the plastic endo-training blocks and sterilised for the three times subgroups. Each instrument in subgroups was cut into four small segments of 4–5 mm. All segments of instruments were analysed using Differential Scanning Calorimetry (DSC). Data was collected and analysed using SPSS version 20.0 with ANOVA test or Kruskal–Wallis test at the significant level of 0.05. Results There was not significant difference between before and after simulated clinical use with sterilised procedure in three NiTi instrument systems. The austenite-finish (Af) temperatures of three instrument systems were higher than that of the human body (37 °C), of these, the Af temperature of Neoniti was highest and that of HyFlex CM Pro was lowest. Conclusions The austenite-finish (Af) temperatures of three NiTi instruments were higher than that of human body temperature, therefore, material was in the phase transformation from martensite to austenite, gives the instruments more flexibility when used in the clinical situation.

An Investigation of the Automatic Relative Gravimeters

2013 ◽  
Vol 199 ◽  
pp. 261-266 ◽  
Author(s):  
Eimuntas Parseliunas ◽  
Petras Petroškevičius ◽  
Romuald Obuchovski ◽  
Rosita Birvydiene
Keyword(s):  
Elastic System ◽  
Zero Drift ◽  
Maximum Difference ◽  
Linear Scale ◽  
Field Investigations ◽  
Different Types ◽  
Before And After ◽  
The Difference ◽  
Field Works ◽  
Gravity Acceleration

The laboratory and field investigations of the several automatic gravimeters Scintrex CG_5 with a quartz elastic system used for the determining of gravity acceleration were performed. Research on characteristics of four gravimeters includes a five-year period. The data consists of gravimetric observations at a laboratory, on the gravimetric testline and at the points of the Lithuanian gravimetric network. The evaluation of the phenomena of the spring systems of the gravimeters was made. The stress on the estimation of the zero drift at a laboratory and field investigations was done. It was detected that zero drift does not exceed 500 μGal per day with a diapason of 200 μGal. The zero drifts per hour do not exceed 25 μGal, mostly they are under 10 μGal. According to the annual calibration results the character of the changes of the linear scale coefficients of the gravimeters were analysed too. The calibration base of 270 km length in Lithuania where the difference of the gravity acceleration of the end points is 201 mGal was used for investigations. The research showed that the biggest deviation from the unit of the linear scale coefficients does not exceed 0.013. It was noted, that the values of the linear scale coefficients of the gravimeters have a tendency to decrease. Also was noted, that the values of the linear scale coefficients have a tendency to decrease in the period between field works, and to increase - in the field works period. So the calibration of the gravimeters should be carried out before and after the field works. Based on measurements carried out during development of the Lithuanian gravimetric network, which consists of 686 gravimetric points, accuracy of gravity acceleration increments was assessed. The comparison of the observations results against the results, obtained by the LaCoste and Romberg gravimeters with metal elastic system, is presented too. The total number of common points is 51. It was stated, that the differences of the gravity accelerations measured by the different types of gravimeters at gravimetric points do not differ more than 10 μGal, therefore maximum difference of 25 μGal was received. The standard deviations of the gravity accelerations of the gravimetric points do not exceed 7 μGal. Such results show the good performance of the SCINTREX CG_5 gravimeters.

Heat debt as an index for cold adaptation in men

1987 ◽  
Vol 62 (4) ◽  
pp. 1627-1634 ◽  
Author(s):  
J. H. Bittel
Keyword(s):  
Body Temperature ◽  
Cold Adaptation ◽  
Cold Test ◽  
Mean Body Temperature ◽  
Body Fat Content ◽  
Different Types ◽  
Before And After ◽  
The Difference ◽  
Temperature Levels ◽  
Male Subjects

Several types of cold adaptation in men have been described in the literature (metabolic, insulative, hypothermic). The aim of this study is to show that the decrease of heat debt can be considered as a new index for cold adaptation. Ten male subjects were acclimated by water immersions (temperature 10–15 degrees C, 4 immersions/wk over 2 mo). Thermoregulatory responses before and after acclimation were tested by a standard cold test in a climatic chamber for 2 h at rest [dry bulb temperature (Tdb): 10 degrees C; relative humidity (rh): 25%]. After adaptation, four thermoregulatory modifications were observed: an increase in the delay for the onset of shivering (32.7 +/- 7.99 instead of 14.1 +/- 5.25 min); a decrease of body temperature levels for the onset of shivering [rectal temperature (Tre): 37.06 +/- 0.08 instead of 37.31 +/- 0.06 degrees C; mean skin temperature (Tsk): 24.83 +/- 0.56 instead of 26.86 +/- 0.46 degrees C; mean body temperature (Tb): 33.03 +/- 0.20 instead of 34.16 +/- 0.37 degrees C); a lower level of body temperatures in thermoneutrality (Tre = 37.16 +/- 0.08 instead of 37.39 +/- 0.06 degrees C; Tsk = 31.29 +/- 0.21 instead of 32.01 +/- 0.22 degrees C; Tb = 35.92 +/- 0.08 instead of 36.22 +/- 0.05 degrees C); a decrease of heat debt calculated from the difference between heat gains and heat losses (5.66 +/- 0.08 instead of 8.33 +/- 0.38 kJ/kg). The different types of cold adaptation observed are related to the physical characteristics of the subjects (percent body fat content) and the level of physical fitness (VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Adding a Stone Base on the Accuracy of Working Casts Using Different Types of Dental Stone

2006 ◽  
Vol 7 (4) ◽  
pp. 17-28 ◽  
Author(s):  
Ayman Ellakwa ◽  
Khalid Al-Abidi
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Univariate Analysis ◽  
Posterior Teeth ◽  
Base Materials ◽  
Significant Difference ◽  
Different Types ◽  
Before And After ◽  
Master Model ◽  
The Difference

Abstract Aim Gypsum products are used for the preparation of stone casts of oral and maxillofacial structures and as important adjuncts to dental laboratory operations involved in the production of dental prostheses. The aim of this study was to determine the effect on the dimensional accuracy of a working cast of adding a stone base using different stone products. Methods and Materials A total of forty impressions of a mandibular dentoform were made. The impressions were dried with compressed air and stored at room temperature for 24 hours before pouring stone casts. The forty impressions were randomly divided into four groups of ten each. All forty impressions were poured once using one pre-weighed 140 Gm package of Silky Rock (SR) Type IV improved stone (Whip Mix Corporation, Louisville, KY, USA) per impression. All working casts and the die setups were prepared according to the manufacturer's recommendations for pin placement (M.R. Dual pin and sleeve). Four different types of dental stone (II, III, and IV) and Flow Stone (FS) were used as bases for the working models. They were mixed according to the manufacturer's recommendations. The lower posterior teeth were flattened on the dentoform prior to taking the impressions. All were indexed using a mounted abrasive disc. Four teeth were selected as follows: 21, 28, 30, and 18. These represented A, B, C, and D landmarks, respectively. All measurements (five times for each specimen) were made with a Universal measuring microscope (Unitron Instruments, Inc., Bohemia, NY, USA). After the pre-sectioned measurements were recorded, the stone base was poured. A manual hand saw was used to section and fabricate removable dies for the mandibular landmarks A, B, C, and D. The dies were later seated and removed ten times to simulate the average amount of handling during laboratory procedures. Each die was carefully seated and measurements were made using the same technique as for the master model and unsectioned casts. Multivariate repeated measures analysis of variance (MANOVA) was used to test the difference in three different landmark distances (AB, AC, and AD) among the master model before and after sectioning of the working dies and among the four different base materials. Univariate analysis of variance (ANOVA) was conducted for each measurement, AB, AC, and AD to test the difference in landmark distances on the master model at pre sectioning and then at post sectioning using four different base materials. When there was a significant main effect (p < .05), the Student-Newman-Keul's (SNK) were used to test for pair wise comparison of means (P<0.05). Results The results of the MANOVA indicated there was a significant difference in three landmark measurements on the master model before and after sectioning of the working dies for the four different base materials (F=6.60, p=0.0001). In addition there was a significant difference in three landmark measurements on the master model at: (1) pre sectioning (p=0.0001), (2) between the master model and SR material (p=0.0002), (3) between the master model and Laboratory Plaster (LP) material (p=0.0001), (4) between the master model and Quick Stone (QS) material (p=0.0001), and (5) between the master model and FS material (p=0.0001). Citation Al-Abidi K, Ellakwa A. The Effect of Adding a Stone Base on the Accuracy of Working Casts Using Different Types of Dental Stone. J Contemp Dent Pract 2006 September;(7)4:017-028.

scholarly journals Cyclic Fatigue Resistance of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals

2013 ◽  
Vol 24 (2) ◽  
pp. 117-120 ◽  
Author(s):  
Oscar Faciola Pessoa ◽  
Juliana Melo da Silva ◽  
Giulio Gavini
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Time To Failure ◽  
Clinical Use ◽  
Root Canals ◽  
Niti Instruments ◽  
Number Of Cycles ◽  
Curved Root Canals

The aim of this study was to assess cyclic fatigue resistance in rotary nickel-titanium instruments after simulated clinical use in curved root canals (40-degree, 5-mm radius curve). Thirty-six RaCe rotary NiTi files, size #5, taper 0.04, were divided into 3 groups: Groups A, B and C with one, three and five cycles of use, respectively. Time to failure was recorded with a stopwatch in seconds and subsequently converted to number of cycles to fracture. The data were analyzed statistically by ANOVA and Tukey's test (α=0.05). Five sets of clinically used files (group C) reached significantly lower cycle-numbers before fracture (mean=197.5 cycles) when compared with one set of clinically used files (mean=309.2) and three sets (mean=287.5). Results showed that the number of simulated clinical uses of RaCe instruments for shaping curved canals affects adversely the fatigue resistance of these instruments after five uses.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

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