scholarly journals Effect of the action of diamond burs with high speed on the tensile strength of cores cemented with zinc phosphate at different preparation times

2015 ◽  
Vol 63 (4) ◽  
pp. 405-410
Author(s):  
Vanilde Rocha Rodrigues
Keyword(s):  
Tensile Strength ◽  
Statistical Analysis ◽  
High Speed ◽  
Zinc Phosphate ◽  
Metallic Core ◽  
The Core ◽  
Significant Difference ◽  
To Receive ◽  
Cobalt Chrome Alloy ◽  
Cobalt Chrome

Objective: To know the finishing effect, in order to be able to safely proceed with the cores preparation in the daily clinic, without compromising the prosthetic restoration longevity. Methods: This study used 48 human single-rooted premolars, which after the section of its crowns, were endodontically treated, and its root canal prepared 8 mm deep to receive cores casting in cobalt-chrome alloy. Cementing was made with zinc phosphate and the tensile test performed at different preparation times: G1 - without re-preparation after cementation (control); G2 - re-prepared 24 hours after cementation, and G3 - re-prepared 15 minutes after cementation. Results: Statistical analysis showed no significant difference in the tensile strength values in the different groups (p = 0.233), in other words, the core re-preparation 15 minutes or 24 hours after the cementation caused no significant reduction in tensile strength between the core and the root remaining when using the zinc phosphate cement. Conclusion: The metallic core re-preparation cast 15 minutes or 24 hours after cementation caused no significant reduction in tensile strength between the cast metallic core and the root remaining, although in absolute values there was an important difference.

scholarly journals Effect of cement types on the tensile strength of metallic crowns submitted to thermocycling

2003 ◽  
Vol 14 (3) ◽  
pp. 193-196 ◽  
Author(s):  
Simonides Consani ◽  
Julie Guzela dos Santos ◽  
Lourenço Correr Sobrinho ◽  
Mário Alexandre Coelho Sinhoreti ◽  
Manoel Damião Sousa-Neto
Keyword(s):  
Tensile Strength ◽  
Zinc Phosphate ◽  
Testing Machine ◽  
Glass Ionomer Cement ◽  
Tensile Load ◽  
Resin Cement ◽  
Glass Ionomer ◽  
Significant Difference ◽  
Resin Modified Glass Ionomer ◽  
Ionomer Cement

The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10º tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.

scholarly journals Influence of activation modes on diametral tensile strength of dual-curing resin cements

2005 ◽  
Vol 19 (4) ◽  
pp. 267-271 ◽  
Author(s):  
Renata Garcia Fonseca ◽  
Juliana Gomes dos Santos ◽  
Gelson Luis Adabo
Keyword(s):  
Tensile Strength ◽  
Zinc Phosphate ◽  
Chemical Activation ◽  
Testing Machine ◽  
Resin Cement ◽  
The Self ◽  
Resin Cements ◽  
Significant Difference ◽  
Dual Curing ◽  
Diametral Tensile Strength

In metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. The effect of the lack of photoactivation on the strength of these cements has been rarely studied. This study evaluated the influence of activation modes on the diametral tensile strength (DTS) of dual-curing resin cements. Base and catalyst pastes of Panavia F, Variolink II, Scotchbond Resin Cement, Rely X and Enforce were mixed and inserted into cylindrical metal moulds (4 x 2 mm). Cements were either: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated through mylar strips (chemical and photo-activation = dual-cured groups) (n = 10). After a 24 h storage in 37ºC distilled water, specimens were subjected to compressive load in a testing machine. A self-curing resin cement (Cement-It) and a zinc phosphate cement served as controls. Comparative analyses were performed: 1) between the activation modes for each dual-curing resin cement, using Student’s t test; 2) among the self-cured groups of the dual-curing resin cements and the control groups, using one-way ANOVA and Tukey’s test (alpha = 0.05). The dual-cured groups of Scotchbond Resin Cement (53.3 MPa), Variolink II (48.4 MPa) and Rely X (51.6 MPa) showed higher DTS than that of self-cured groups (44.6, 40.4 and 44.5 MPa respectively) (p < 0.05). For Enforce (48.5 and 47.8 MPa) and Panavia F (44.0 and 43.3 MPa), no significant difference was found between the activation modes (p > 0.05). The self-cured groups of all the dual-curing resin cements presented statistically the same DTS as that of Cement-It (44.1 MPa) (p > 0.05), and higher DTS than that of zinc phosphate (4.2 MPa). Scotchbond Resin Cement, Variolink II and Rely X depended on photoactivation to achieve maximum DTS. In the absence of light, all the dual-curing resin cements presented higher DTS than that of zinc phosphate and statistically the same as that of Cement-It (p > 0.05).

scholarly journals Effect of different EGTA concentrations on dentin microhardness

2002 ◽  
Vol 13 (3) ◽  
pp. 188-190 ◽  
Author(s):  
Antonio Miranda da Cruz-Filho ◽  
Eduardo Augusto de Paula ◽  
Jesus Djalma Pécora ◽  
Manoel Damião de Sousa-Neto
Keyword(s):  
Acetic Acid ◽  
Statistical Analysis ◽  
High Speed ◽  
Acrylic Resin ◽  
Distilled Water ◽  
Three Solutions ◽  
Human Teeth ◽  
Tukey Test ◽  
Significant Difference ◽  
Root Dentin

The effect of 1%, 3% and 5% EGTA (ethylene glycol-bis-(b-amino-ethyl ether) N,N,N´,N´-tetra-acetic acid) on the microhardness of root dentin of the cervical third of human teeth was studied. Five newly extracted maxillary incisors were sectioned transversely at the cementoenamel junction, and the crowns were discarded. The roots were embedded in blocks of high-speed polymerized acrylic resin and cut transversely into 1-mm sections. The second section of the cervical third of the root of each tooth was sectioned and divided into four parts. Each part was placed on an acrylic disc that was used as a base for microhardness measurement. Fifty microliters of 1% EGTA, 3% EGTA, or 5% EGTA were applied to the dentin surface. Deionized and distilled water was used as control. Dentin microhardness was then measured with a load of 50 g for 15 s. Statistical analysis showed that the three concentrations of the chelating solution EGTA significantly reduced dentin microhardness when compared with water (ANOVA, p<0.01), and that there was a statistically significant difference among the three solutions (Tukey test, p<0.05).

scholarly journals The Efficacy of High-Volume Evacuators and Extraoral Vacuum Aspirators in Reducing Aerosol and Droplet in Ultrasonic Scaling Procedures during the COVID-19 Pandemic

2022 ◽  
Author(s):  
Trijani Suwandi ◽  
Vidya Nursolihati ◽  
Mikha Sundjojo ◽  
Armelia Sari Widyarman
Keyword(s):  
Statistical Analysis ◽  
High Speed ◽  
High Volume ◽  
Limited Data ◽  
Dental Procedures ◽  
Significant Difference ◽  
Kolmogorov Smirnov ◽  
Airborne Disease ◽  
Better Than ◽  
Smirnov Test

Abstract Objective SARS-CoV-2 can be carried by aerosols and droplets produced during dental procedures, particularly by the use of high-speed handpieces, air-water syringes, and ultrasonic scalers. High-volume evacuators (HVEs) and extraoral vacuum aspirators (EOVAs) reduce such particles. However, there is limited data on their efficacy. This study aimed to determine the efficacy of HVE and EOVA in reducing aerosols and droplets during ultrasonic scaling procedures. Materials and Methods Three ultrasonic scaling simulations were conducted on mannequins: 1. saliva ejector (SE) was used alone (control); 2. SE was used in combination with HVE; and 3. SE was used in combination with HVE and EOVA. Paper filters were placed on the operator's and assistant's face shields and bodies, and the contamination of aerosols and droplets was measured by counting blue spots on the paper filters. Statistical Analysis All data were analyzed for normality using the Kolmogorov–Smirnov test. The differences between each method were analyzed using a two-way ANOVA, followed by a posthoc test. The differences were considered statistically significant when p < 0.05 Result Using HVE and EOVA reduced aerosols and droplets better than using SE alone or SE and HVE: the posthoc test for contamination revealed a significant difference (p < 0.01). The assistant was subjected to greater contamination than the operator during all three ultrasonic scaling procedures. Conclusion The usage of HVE and EOVA significantly reduced aerosols and droplets compared with using SE solely. Using these techniques together could prevent the transmission of airborne disease during dental cleanings, especially COVID-19. Further studies of aerosol-reducing devices are still needed to ensure the safety of dental workers and patients.

scholarly journals Waiting Time for Coronal Preparation and the Influence of Different Cements on Tensile Strength of Metal Posts

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Ilione Kruschewsky Costa Sousa Oliveira ◽  
Ynara Bosco de Oliveira Lima Arsati ◽  
Roberta Tarkany Basting ◽  
Fabiana Mantovani Gomes França
Keyword(s):  
Tensile Strength ◽  
Waiting Time ◽  
Zinc Phosphate ◽  
Tensile Load ◽  
Root Apex ◽  
Load Test ◽  
Resin Cement ◽  
The Core ◽  
Nickel Chromium ◽  
Retention Strength

This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16 mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP) cement or resin cement (RC), the specimens were divided into 3 groups (n= 10) according to the waiting time for core preparation: no preparation (control), 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5 mm/min) until failure. Two-way ANOVA (time versus cement) and the Tukey tests (P< 0.05) showed significantly higher (P< 0.05) tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation.

scholarly journals The Effects of a Preoperative Steroid/Anesthetic Injection on Post-Tonsillectomy Pain

2003 ◽  
Vol 82 (4) ◽  
pp. 305-308 ◽  
Author(s):  
Timothy M. Cupero ◽  
Sam Y. Kim ◽  
Andrew B. Silva
Keyword(s):  
Statistical Analysis ◽  
Postoperative Pain ◽  
Active Treatment ◽  
Generalized Estimating Equations ◽  
Blind Study ◽  
Significant Difference ◽  
The Right ◽  
And Control ◽  
To Receive ◽  
Single Blind

We conducted a placebo-controlled, single-blind study to determine the efficacy of a local preoperative injection of a steroid/anesthetic combination in preventing post-tonsillectomy pain. We randomized 21 adults to receive either triamcinolone/bupivacaine on the left side and saline on the right or vice versa. Injections were administered in the area of the tonsillar pillars following intubation and prior to tonsillectomy. Based on the “generalized estimating equations” model of statistical analysis, we found no significant difference in the degree of postoperative pain between the active-treatment and control sides.

scholarly journals Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts

2006 ◽  
Vol 17 (2) ◽  
pp. 130-133 ◽  
Author(s):  
Edson Alfredo ◽  
Emanuel Soares de Souza ◽  
Melissa Andréia Marchesan ◽  
Silvana Maria Paulino ◽  
Ricardo Gariba-Silva ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Bond Strength ◽  
Zinc Phosphate ◽  
Tensile Force ◽  
Adhesive Properties ◽  
Crosshead Speed ◽  
Pull Out ◽  
Gutta Percha ◽  
Significant Difference

The present study evaluated, in vitro, the influence of an eugenol-based endodontic sealer (EndoFill) on the adhesion of intra-radicular posts cemented with a resin-based cement (Enforce) ou a zinc phosphate cement. Twenty-four single-rooted maxillary canines were divided into 2 groups (n=12) and obturated with either gutta-percha points plus EndoFill or gutta-percha points alone (no cement). In each group, half of intracanal posts (n=6) were cemented with Enforce resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test in an Instron machine and tensile force was applied at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal was recorded (N) and means were submitted to statistical analysis by Kruskal-Wallis test (p<0.01). Posts cemented with zinc phosphate cement were significantly more retentive (353.4 N) than those cemented with Enforce (134.9 N) (p<0.01). Regarding the influence of the eugenol-based cement (EndoFill) on post retention, there was statistically significant difference (p<0.01) only between the groups cemented with Enforce, i.e., in the canals filled with EndoFill + guta-percha there was lower bond strength than in the canals filled with gutta-percha points alone (101.5 and 168.2 N, respectively). In conclusion, the zinc-phosphate-based cement showed greater post retention than the resin-based cement. The findings of this study suggest that the eugenol-containing sealer interfered with the adhesive properties of the resin-based cement.

Short-Term Bond Strengths Between Adhesive Cements and Dental Alloys

1974 ◽  
Vol 53 (6) ◽  
pp. 1377-1386 ◽  
Author(s):  
J.B. Moser ◽  
D.B. Brown ◽  
E.H. Greener
Keyword(s):  
Stainless Steel ◽  
Zinc Phosphate ◽  
The Other ◽  
304 Stainless Steel ◽  
Dental Alloys ◽  
Short Term ◽  
Bond Strengths ◽  
Almost All ◽  
Cobalt Chrome Alloy ◽  
Cobalt Chrome

The tensile bond strength between three polycarboxylate cements and Types I and III gold, 304 stainless steel, and cobalt-chrome alloy was compared to that obtained with a silico-phosphate and a zinc phosphate cement. The polycarboxylate cements showed higher strengths with almost all alloys than did the other two.

scholarly journals Statistical anatomy of tyrannosaurs

1992 ◽  
Vol 6 ◽  
pp. 1-1
Author(s):  
William L. Abler
Keyword(s):  
Tensile Strength ◽  
Factor Analysis ◽  
Statistical Analysis ◽  
Anatomical Structures ◽  
Filament Diameter ◽  
South Central ◽  
Internal Structures ◽  
Significant Difference ◽  
And Migration ◽  
Source Of Information

Since dinosaur fossils are not numerous enough for statistics, the idea of studying dinosaurs at all has been questioned. Teeth of Judith River tyrannosaurs (late Cretaceous of south-central Alberta, Canada) are sufficiently numerous and rich in anatomical structures for statistical analysis: 1. No difference was found between widths of serrations of anterior and posterior rows (Mann-Whitney U test, two-tailed; n = 24 tooth fragments: p> .05; anterior and posterior x = 0.4 mm): 2. Reversals in uniform trends in serration width within each serration row were more numerous for the anterior (reversals = 51; non-reversals = 74) than for the posterior (reversals = 45; non-reversals = 135) serration rows (χ2 (2×2) = 7.82; d.f. = 1; p< .01); 3. Serrations of the anterior row are more steeply angled toward the point of the tooth than are those of the posterior row (Mann-Whitney U test, two-tailed, n = 21 tooth fragments; p< .01; anterior x̄ = 8.9°; posterior x̄ = 5.0°): 4. Small teeth (mean length = 9.8mm) show less tendency to be scratched than large ones (mean length = 25.0mm) (t(d.f. = 234) = 4.64; p< .01); 5. Inter-serrational slots of posterior row require less force (x̄ = 0.14 newton) to cut standard nylon filament (diameter = 0.04mm; tensile strength = 0.42 newton) than did slots of the anterior row (x̄ = 0.24 newton; Mann-Whitney U test, two-tailed; p< .05; n = 17 fragments); 6. There is a significant difference between edge radii r (expressed in microns μ) of serrations of three classes of tyrannosaur teeth: unerupted/partially erupted (x̄ = 78.2μ), vs. fully erupted but still attached to bone (x̄ = 94.7μ), vs. shed (x̄ = 139.3μ) teeth (two factor analysis of variance, F(2,173) = 10.86; p< .05). Teeth of Judith River tyrannosaurs possess numerous structures, both interior and exterior (see figure) whose geometry differs markedly from that of, e.g., troodon teeth (which may possess a radix, but no other differentiated internal structures), or thecodont teeth (which possess a peak of interior enamel intruding into each denticle and tilted toward the point of the tooth). Statistical anatomy of teeth may offer a rich source of information for studying taxonomy, evolution, and migration of tyrannosaurs.

The Use of Twisting and Tightening Tool to Strengthen the Cerclage and Tension Band Wiring

2020 ◽  
pp. 155335062096533
Author(s):  
Esat Uygur ◽  
Mehmet A. Yayla ◽  
Yakup Yürektürk ◽  
Fuat Akpinar
Keyword(s):  
Tensile Strength ◽  
Statistical Analysis ◽  
Tension Band ◽  
Tension Band Wiring ◽  
Cerclage Wire ◽  
Significant Difference ◽  
Group A ◽  
The Mean ◽  
Group B ◽  
Biomechanical Tests

Cerclage and tension band wiring are being used in most bone surgeries in different disciplines. The regularity of the twist on the node of a cerclage and tension band is thought to determine cerclage stability. For this purpose, a novel twisting and tightening tool was designed. This tool maintains extremely regular twists on the node, which we consider to be important for stability. In the present biomechanical trial, we aimed to investigate the consistency of the twists forming the cerclage node. This study was performed on a total of 30 cerclage loops. In group A (n = 15), the cerclage wire was tightened manually by a clipper, while in group B (n = 15), it was tightened using the twisting and tightening tool. In biomechanical tests, the cerclage loops were pulled apart by 2 hooks connected to the biomechanical device. The velocity was adjusted to 20 mm/min. On statistical analysis, there was a significant difference in the ultimate strength ( P = .03) and the mean tensile strength ( P = .01) between groups A and B. It was found that the strength of the cerclage wire can be increased by maintaining more regular twists. The twisting and tightening tool is a reasonable and useful device for both clinical and experimental usages.

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