Alumina Femoral Head Fracture: An in Vitro Study

2000 ◽  
Vol 23 (4) ◽  
pp. 256-260 ◽  
Author(s):  
S. Affatato ◽  
E. Ghisolfi ◽  
G.L. Cacciari ◽  
A. Toni
Keyword(s):  
Stainless Steel ◽  
Femoral Head ◽  
In Vitro Study ◽  
Detailed Examination ◽  
Femoral Head Fracture ◽  
Acetabular Cup ◽  
Ceramic Ball ◽  
Ceramic Femoral Head ◽  
Hip Simulator

A fracture of a ceramic femoral head is reported in this study. Fractures of ceramic femoral heads are uncommon and reports on this complication are rare. After 3 million cycles, on a twelve station hip simulator that tested alumina femoral head against polyethylene acetabular cup, fracture of the ceramic ball was observed. The retrieved specimen consisted of three large ceramic fragments from the same ceramic femoral head, a polyethylene acetabular cup and a stainless steel jig. Careful and detailed examination of the removed components was made. The fracture of the ceramic ball resulted in damage to the metal taper of the jig component which was fixed into the simulator.

scholarly journals Scanning Accuracy of Bracket Features and Slot Base Angle in Different Bracket Materials by Four Intraoral Scanners: An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 365
Author(s):  
Seon-Hee Shin ◽  
Hyung-Seog Yu ◽  
Jung-Yul Cha ◽  
Jae-Sung Kwon ◽  
Chung-Ju Hwang
Keyword(s):  
Stainless Steel ◽  
In Vitro Study ◽  
Sem Images ◽  
Polycrystalline Alumina ◽  
Base Angle ◽  
Accurate Expression ◽  
Dental Model ◽  
Alumina Composite ◽  
The Difference

The accurate expression of bracket prescription is important for successful orthodontic treatment. The aim of this study was to evaluate the accuracy of digital scan images of brackets produced by four intraoral scanners (IOSs) when scanning the surface of the dental model attached with different bracket materials. Brackets made from stainless steel, polycrystalline alumina, composite, and composite/stainless steel slot were considered, which have been scanned from four different IOSs (Primescan, Trios, CS3600, and i500). SEM images were used as references. Each bracket axis was set in the reference scan image, and the axis was set identically by superimposing with the IOS image, and then only the brackets were divided and analyzed. One-way analysis of variance (ANOVA) was used to compare the differences. The difference between the manufacturer’s nominal torque and bracket slot base angle was 0.39 in SEM, 1.96 in Primescan, 2.04 in Trios, and 5.21 in CS3600 (p < 0.001). The parallelism, which is the difference between the upper and lower angles of the slot wall, was 0.48 in SEM, 7.00 in Primescan, 5.52 in Trios, 6.34 in CS3600, and 23.74 in i500 (p < 0.001). This study evaluated the accuracy of the bracket only, and it must be admitted that there is some error in recognizing slots through scanning in general.

scholarly journals Metals and Metalloids Release from Orthodontic Elastomeric and Stainless Steel Ligatures: In Vitro Risk Assessment of Human Exposure

2019 ◽  
Vol 196 (2) ◽  
pp. 646-653 ◽  
Author(s):  
Aneta Olszewska ◽  
Anetta Hanć ◽  
Danuta Barałkiewicz ◽  
Piotr Rzymski
Keyword(s):  
Stainless Steel ◽  
Inductively Coupled Plasma ◽  
Human Exposure ◽  
Orthodontic Treatment ◽  
In Vitro Study ◽  
Human Saliva ◽  
Metal Exposure ◽  
Monthly Basis ◽  
Metal Levels

Abstract Elastomeric ligatures are increasingly used as a part of esthetic orthodontic treatment, particularly in children. The aim of the present study was to experimentally test whether these appliances may contribute to exposure to toxic elements. In the present study, elastomeric ligatures (ELs) were incubated in artificial human saliva for 1 month (a typical period of their use) and the release of 21 metals (Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mg, Mo, Ni, Pb, Rb, Tl, Ti, Sb, Sr, Sn, Zn, U, V) and 2 metalloids (As and Ge) was studied using inductively coupled plasma–mass spectrometry. For comparison, stainless steel ligatures (SLs) were incubated for 1, 3, and 6 months (since sometimes their use is prolonged) under similar conditions. The determined metal levels were compared to the corresponding safety limits for human exposure. During 1 month, the ELs released Cd, Co, Cr, Mn, Ni, and Sn at total mean ± SD level of 0.31 ± 0.09, 0.98 ± 0.30, 3.96 ± 1.31, 14.7 ± 8.5, 13.8 ± 4.8, and 49.5 ± 27.7 μg, respectively. Other elements were always below the detection limits. In case of SL, the release of Co, Cr, Fe, Ni, Mn, and Sn was observed, and the determined values increased over the studied period. After 6 months, their total mean ± SD levels amounted to 28.6 ± 0.2, 21.7 ± 0.2, 623.5 ± 3.0, 1152.7 ± 1.8, 5.5 ± 0.3, and 22.6 ± 0.2 μg, respectively. The released metal levels from both ligature types were always below safety limits. The release of Ni from SL during 6 months would constitute 5.0 and 11.5% of tolerable intake in adults and children, respectively. The results of this in vitro study highlight that the use of ligatures in orthodontic treatment can be considered safe in terms of metal exposure although elastic ligatures replaced on a monthly basis appear to be advantageous in comparison to the prolonged use of stainless steel appliances.

A Study of the Wear Characteristics of Sliding Pairs of High Density Polycrystalline Aluminium Oxide with Particular Reference to Their Use in Total Replacement Human Joints

1983 ◽  
Vol 12 (1) ◽  
pp. 23-28 ◽  
Author(s):  
N Wallbridge ◽  
D Dowson ◽  
E W Roberts
Keyword(s):  
Femoral Head ◽  
High Density Polyethylene ◽  
High Density ◽  
Wear Testing ◽  
Distilled Water ◽  
Acetabular Cup ◽  
Wear Characteristics ◽  
Total Replacement ◽  
Ceramic Femoral Head ◽  
Dry Conditions

The introduction of ceramic components into total replacement joints for the human body in the last decade has attracted considerable attention. In most cases in which a ceramic component is used a ceramic femoral head is located on a metallic femoral stem, whilst the acetabular cup is made from ultra high molecular weight polyethylene. In some designs a ceramic acetabular cup is used in association with the ceramic femoral head. A study of the basic wear characteristics of sliding pairs of high density polycrystalline ceramics is reported in this paper. Tests have been carried out under both ‘dry’ and ‘wet’ (distilled water) conditions in a tri-pin-on-disc wear testing machine. It is shown that sliding pairs of alumina ceramics exhibit remarkably low wear under dry conditions when subjected to small loads, but that high loads lead to rapid deterioration of the interacting surfaces and the onset of very high wear rates. The presence of distilled water generally permits smooth sliding at higher loads than are possible under dry conditions, but the wear rate increases by a factor of about ten over those encountered at low loads in air. The slight advantage of sliding pairs of alumina over high density polyethylene sliding on stainless steel as far as wear is concerned is not evident if the comparison is made with high density polyethylene sliding on high density ceramic in the presence of distilled water.

Degree of Conversion of Three Light-Cured Orthodontic Adhesives

2018 ◽  
Vol 777 ◽  
pp. 577-581
Author(s):  
Wassana Wichai ◽  
Kanin Nimcharoensuk ◽  
Niwat Anuwongnukroh ◽  
Surachai Dechkunakorn ◽  
Pitchaya Roongrujimek
Keyword(s):  
Stainless Steel ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
In Vitro Study ◽  
Degree Of Conversion ◽  
Friedman Test ◽  
Orthodontic Adhesives ◽  
Time Periods

Introduction: The aim of this in-vitro study was to analyze the polymerization ability of 3 light-cured orthodontic adhesives by determining the degree of conversion (DC). Materials and Methods: Fourier transform infrared spectroscopy (FTIR) was used to evaluate the DC after polymerization immediately, 1 day, 7 days, and 30 days. The adhesives investigated were Transbond XT (3M Unitek, USA), Grengloo (Ormco Corp., USA), and Green Glue (Hangzhou Biomaterials, China). Twelve stainless steel brackets (n=4) were used and the adhesives were cured with Bluephase G2 (Ivoclar Vivadent, Liechtenstein). The data were analyzed by Kruskal-Wallis test for comparing materials and Friedman test for comparing the time periods. Results: The DC values were significantly different among the materials and among the time periods. The highest DC in each period was obtained for Grengloo and the lowest DC was observed for Transbond XT. Thus, there were significant differences between the DC values of Grengloo and Transbond XT in each period. Among the time periods, DC% at T1 (Immediately) and T3 of the material were significantly different. The DC values of all adhesives increased extremely from immediately following curing to 1 day and then slightly increased from 1 day to 7 days. Conclusions: Grengloo showed the highest levels of DC at all tested periods. The percentage values of DC largely increased from immediately following curing to 1 day. This concluded that monomers in orthodontic adhesives kept converting even after completion of photoactivation.

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