Summary: A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics.

Top Publications

  1. Parra Robles J, Ajraoui S, Deppe M, Parnell S, Wild J. Experimental investigation and numerical simulation of 3He gas diffusion in simple geometries: implications for analytical models of 3He MR lung morphometry. J Magn Reson. 2010;204:228-38 pubmed publisher
    ..The results presented here demonstrate that physical assumptions of the cylinder model are not valid for large diffusion gradient strengths (above approximately 15 mT/m), which are commonly used for (3)He ADC measurements in human lungs...
  2. Queiroga F, Nunes M, Meda E, Chiappa G, Machado M, Nery L, et al. Exercise tolerance with helium-hyperoxia versus hyperoxia in hypoxaemic patients with COPD. Eur Respir J. 2013;42:362-70 pubmed publisher
    The purpose of this study was to investigate whether helium-hyperoxia (HeHOx) would allow greater tolerance to maximal and submaximal exercise compared to hyperoxia (HOx) on isolation in hypoxaemic chronic obstructive pulmonary disease (..
  3. Martin A, Katz I, Terzibachi K, Gouinaud L, Caillibotte G, Texereau J. Bench and mathematical modeling of the effects of breathing a helium/oxygen mixture on expiratory time constants in the presence of heterogeneous airway obstructions. Biomed Eng Online. 2012;11:27 pubmed publisher
    ..Breathing low-density helium/oxygen mixtures may modify regional time constants so as to redistribute ventilation, potentially reducing gas ..
  4. Zhuang L, Yang T, Zhao H, Fidalgo A, Vizcaychipi M, Sanders R, et al. The protective profile of argon, helium, and xenon in a model of neonatal asphyxia in rats. Crit Care Med. 2012;40:1724-30 pubmed publisher
    Xenon provides neuroprotection in multiple animal models; however, little is known about the other noble gases. The aim of the current study was to compare xenon, argon, and helium neuroprotection in a neonatal asphyxia model in rats.
  5. Shvartsburg A, Danielson W, Smith R. High-resolution differential ion mobility separations using helium-rich gases. Anal Chem. 2010;82:2456-62 pubmed publisher
    ..The resolution gains extend to small molecules, where previously unresolved isomers can now be separated. These performance levels open major new applications of FAIMS in proteomic and other biomolecular analyses...
  6. Sato T, Funamori N, Yagi T. Helium penetrates into silica glass and reduces its compressibility. Nat Commun. 2011;2:345 pubmed publisher
    ..Here we show anomalous behaviour of SiO(2) glass in helium. Volume measurements clarify that SiO(2) glass is much less compressible than normal when compressed in helium, ..
  7. Yang Y, Wang C, Lu Y, Bai W, An L, Qu J, et al. Outcomes of ultrasound-guided percutaneous argon-helium cryoablation of hepatocellular carcinoma. J Hepatobiliary Pancreat Sci. 2012;19:674-84 pubmed publisher
    To evaluate the efficacy and safety of ultrasound (US)-guided percutaneous argon-helium cryoablation for hepatocellular carcinoma (HCC) and determine appropriate indications.
  8. Sukstanskii A, Conradi M, Yablonskiy D. ³He lung morphometry technique: accuracy analysis and pulse sequence optimization. J Magn Reson. 2010;207:234-41 pubmed publisher
    ..It is demonstrated that the optimal choice represents three not equidistant b-values: b(1)=0, b(2)?2 s/cm(2), b(3)?8 s/cm(2)...
  9. Ferreira da Silva F, Ptasinska S, Denifl S, Gschliesser D, Postler J, Matias C, et al. Electron interaction with nitromethane embedded in helium droplets: attachment and ionization measurements. J Chem Phys. 2011;135:174504 pubmed publisher
    Results of a detailed study on electron interactions with nitromethane (CH(3)NO(2)) embedded in helium nanodroplets are reported. Anionic and cationic products formed are analysed by mass spectrometry...

More Information


  1. Li M, Zhang S, Zhou Y, Guo Y, Jiang X, Miao L. Argon-helium cryosurgery for treatment of C6 gliomas in rats and its effect on cellular immunity. Technol Cancer Res Treat. 2010;9:87-94 pubmed
    Argon-helium cryosurgery has shown encouraging therapeutic effects on some solid tumors, but its application in the treatment of gliomas remains poorly documented...
  2. Hussain O, Collins E, Adiguzel N, Langbein W, Tobin M, Laghi F. Contrasting pressure-support ventilation and helium-oxygen during exercise in severe COPD. Respir Med. 2011;105:494-505 pubmed publisher
    b>Helium-oxygen mixtures and pressure-support ventilation have been used to unload the respiratory muscles and increase exercise tolerance in COPD...
  3. O Donnell C, Bankier A, Stiebellehner L, Reilly J, Brown R, Loring S. Comparison of plethysmographic and helium dilution lung volumes: which is best for COPD?. Chest. 2010;137:1108-15 pubmed publisher
    ..We sought to compare plethysmography (Pleth)-, helium dilution (He)- and CT scan-derived lung volume measurements in a sample containing many patients with severe ..
  4. Mitsuoka K. Obtaining high-resolution images of biological macromolecules by using a cryo-electron microscope with a liquid-helium cooled stage. Micron. 2011;42:100-6 pubmed publisher
    ..for high-resolution imaging in these three different methods, based on our experiences using cryo-EM with a liquid-helium cooled stage...
  5. Liet J, Ducruet T, Gupta V, Cambonie G. Heliox inhalation therapy for bronchiolitis in infants. Cochrane Database Syst Rev. 2010;:CD006915 pubmed publisher
    Acute viral bronchiolitis is associated with airway obstruction and turbulent gas flow. Heliox, a mixture of oxygen and the inert gas helium, may improve gas flow through high-resistance airways and decrease the work of breathing.
  6. Peterson E, Dai J, Holmes J, Fain S. Measurement of lung airways in three dimensions using hyperpolarized helium-3 MRI. Phys Med Biol. 2011;56:3107-22 pubmed publisher
    ..radiation from CT, we present a method for measuring the large airway diameter in humans using hyperpolarized helium-3 (HPHe) MRI in conjunction with a dynamic 3D radial acquisition...
  7. Howard M, Hall M, Edwards J, Vaughn M, PERRON B, Winecker R. Suicide by asphyxiation due to helium inhalation. Am J Forensic Med Pathol. 2011;32:61-70 pubmed
    Suicide by asphyxiation using helium is the most widely-promoted method of "self-deliverance" by right-to-die advocates...
  8. Fain S, Schiebler M, McCormack D, Parraga G. Imaging of lung function using hyperpolarized helium-3 magnetic resonance imaging: Review of current and emerging translational methods and applications. J Magn Reson Imaging. 2010;32:1398-408 pubmed publisher
    During the past several years there has been extensive development and application of hyperpolarized helium-3 (HP (3)He) magnetic resonance imaging (MRI) in clinical respiratory indications such as asthma, chronic obstructive pulmonary ..
  9. Austin A, Winskog C, Van Den Heuvel C, Byard R. Recent trends in suicides utilizing helium. J Forensic Sci. 2011;56:649-51 pubmed publisher
    Retrospective review of cases of suicide involving helium inhalation was undertaken at Forensic Science South Australia over a 25-year period from 1985 to 2009...
  10. Katz I, Martin A, Muller P, Terzibachi K, Feng C, Caillibotte G, et al. The ventilation distribution of helium-oxygen mixtures and the role of inertial losses in the presence of heterogeneous airway obstructions. J Biomech. 2011;44:1137-43 pubmed publisher
    ..In the present work, the effects of heterogeneous airway obstructions on the distribution of air and helium-oxygen were examined using an in vitro model, the two compartments of a dual adult test lung...
  11. Abril I, Garcia Molina R, Denton C, Kyriakou I, Emfietzoglou D. Energy loss of hydrogen- and helium-ion beams in DNA: calculations based on a realistic energy-loss function of the target. Radiat Res. 2011;175:247-55 pubmed
    ..Using this procedure we have calculated the stopping power and the energy-loss straggling of DNA for hydrogen- and helium-ion beams at incident energies ranging from 10 keV/nucleon to 10 MeV/nucleon...
  12. Hodge C, Tome W, Fain S, Bentzen S, Mehta M. On the use of hyperpolarized helium MRI for conformal avoidance lung radiotherapy. Med Dosim. 2010;35:297-303 pubmed publisher
    We wanted to illustrate the feasibility of using hyperpolarized helium magnetic resonance imaging (HPH-MRI) to obtain functional information that may assist in improving conformal avoidance of ventilating lung tissue during thoracic ..
  13. Tustison N, Avants B, Flors L, Altes T, de Lange E, Mugler J, et al. Ventilation-based segmentation of the lungs using hyperpolarized (3)He MRI. J Magn Reson Imaging. 2011;34:831-41 pubmed publisher
    ..To develop an automated segmentation method to differentiate the ventilated lung volume on (3) He magnetic resonance imaging (MRI)...
  14. Chen X, Udalagama C, Chen C, Bettiol A, Pickard D, Venkatesan T, et al. Whole-cell imaging at nanometer resolutions using fast and slow focused helium ions. Biophys J. 2011;101:1788-93 pubmed publisher
    ..Microscopy using helium ions can play a major role in both surface and subcellular imaging because it can provide subnanometer resolutions ..
  15. Roche Campo F, Vignaux L, Galia F, Lyazidi A, Vargas F, Texereau J, et al. Delivery of helium–oxygen mixture during spontaneous breathing: evaluation of three high-concentration face masks. Intensive Care Med. 2011;37:1787-92 pubmed publisher
    To evaluate the efficacy of delivering a mixture of helium and oxygen gas (He–O2) in spontaneous ventilation...
  16. Vanden Berg Foels W, Scipioni L, Huynh C, Wen X. Helium ion microscopy for high-resolution visualization of the articular cartilage collagen network. J Microsc. 2012;246:168-76 pubmed publisher
    ..The recently introduced helium ion microscope (HIM), with its smaller probe size, longer depth of field and charge neutralization, has the ..
  17. Oei G, Huhn R, Heinen A, Hollmann M, Schlack W, Preckel B, et al. Helium-induced cardioprotection of healthy and hypertensive rat myocardium in vivo. Eur J Pharmacol. 2012;684:125-31 pubmed publisher
    b>Helium protects healthy myocardium against ischemia/reperfusion injury by early and late preconditioning (EPC, LPC) and postconditioning (PostC)...
  18. Kirby M, Owrangi A, Svenningsen S, Wheatley A, Coxson H, Paterson N, et al. On the role of abnormal DL(CO) in ex-smokers without airflow limitation: symptoms, exercise capacity and hyperpolarised helium-3 MRI. Thorax. 2013;68:752-9 pubmed publisher
    ..The functional effects of abnormal diffusing capacity for carbon monoxide (DLCO) in ex-smokers without chronic obstructive pulmonary disease (COPD) are not well understood...
  19. Yang J, Ferranti D, Stern L, Sanford C, Huang J, Ren Z, et al. Rapid and precise scanning helium ion microscope milling of solid-state nanopores for biomolecule detection. Nanotechnology. 2011;22:285310 pubmed publisher
    We report the formation of solid-state nanopores using a scanning helium ion microscope...
  20. Kirby M, Svenningsen S, Ahmed H, Wheatley A, Etemad Rezai R, Paterson N, et al. Quantitative evaluation of hyperpolarized helium-3 magnetic resonance imaging of lung function variability in cystic fibrosis. Acad Radiol. 2011;18:1006-13 pubmed publisher
    ..guidance for measurements in individual cystic fibrosis (CF) subjects, we evaluated CF adults on two occasions 7 ± 2 days apart using spirometry, plethysmography, and hyperpolarized helium-3 ((3)He) magnetic resonance imaging (MRI).
  21. Theisen M, Lackner F, Ernst W. Cs atoms on helium nanodroplets and the immersion of Cs+ into the nanodroplet. J Chem Phys. 2011;135:074306 pubmed publisher
    We report the non-desorption of cesium (Cs) atoms on the surface of helium nanodroplets (He(N)) in their 6(2)P(1/2) ((2)?(1/2)) state upon photo-excitation as well as the immersion of Cs(+) into the He(N) upon photo-ionization via the 6(2)..
  22. Kirby M, Heydarian M, Svenningsen S, Wheatley A, McCormack D, Etemad Rezai R, et al. Hyperpolarized 3He magnetic resonance functional imaging semiautomated segmentation. Acad Radiol. 2012;19:141-52 pubmed publisher
    ..MRI) for multicenter, multiobserver studies, we generated a semiautomated segmentation method for hyperpolarized helium-3 ((3)He) MRI...
  23. Boseman A, Nowlin K, Ashraf S, Yang J, Lajeunesse D. Ultrastructural analysis of wild type and mutant Drosophila melanogaster using helium ion microscopy. Micron. 2013;51:26-35 pubmed publisher
    ..In this paper we use a new technology, helium ion microscopy (HIM) to examine surface structures on the cuticle of wild type and mutant Drosophila...
  24. Schöbel H, Leidlmair C, Bartl P, Aleem A, Hager M, Echt O, et al. Ion-molecule reactions of ammonia clusters with C60 aggregates embedded in helium droplets. Phys Chem Chem Phys. 2011;13:1092-8 pubmed publisher
    b>Helium nanodroplets are co-doped with C(60) and ammonia. Mass spectra obtained by electron ionization reveal cations containing ammonia clusters complexed with up to four C(60) units...
  25. Hunt T, Williams M, Frith P, Schembri D. Heliox, dyspnoea and exercise in COPD. Eur Respir Rev. 2010;19:30-8 pubmed publisher
    ..Despite the low density, inert nature, strong safety profile and multiple applications of helium gas, the potential benefit of helium-oxygen gas mixtures as an adjunct therapy to modify disease symptoms and ..
  26. Ghanei M, Rajaeinejad M, Motiei Langroudi R, Alaeddini F, Aslani J. Helium:oxygen versus air:oxygen noninvasive positive-pressure ventilation in patients exposed to sulfur mustard. Heart Lung. 2011;40:e84-9 pubmed publisher
    ..This study assessed the effectiveness of noninvasive positive-pressure ventilation, adjunct with 79:21 helium:oxygen instead of 79:21 air:oxygen, in 24 patients with a previous exposure to SM presenting with acute ..
  27. Ferreira da Silva F, Denifl S, Märk T, Ellis A, Scheier P. Electron attachment to amino acid clusters in helium nanodroplets: glycine, alanine, and serine. J Chem Phys. 2010;132:214306 pubmed publisher
    ..Clusters of these amino acids were formed inside helium nanodroplets, which provide a convenient low temperature (0.37 K) environment for growing noncovalent clusters...
  28. Oei G, Weber N, Hollmann M, Preckel B. Cellular effects of helium in different organs. Anesthesiology. 2010;112:1503-10 pubmed publisher
    ..in cardiac and neuronal tissue has shown that besides volatile anesthetics and xenon, the nonanesthetic noble gas helium also reduces ischemia-reperfusion damage...
  29. Aysola R, de Lange E, Castro M, Altes T. Demonstration of the heterogeneous distribution of asthma in the lungs using CT and hyperpolarized helium-3 MRI. J Magn Reson Imaging. 2010;32:1379-87 pubmed publisher
    ..Thus, cross sectional imaging in asthma is providing new insights into the pathophysiology of the disease and has the potential to become essential in the guidance of localized treatments...
  30. Minard K, Kuprat A, Kabilan S, Jacob R, Einstein D, Carson J, et al. Phase-contrast MRI and CFD modeling of apparent ³He gas flow in rat pulmonary airways. J Magn Reson. 2012;221:129-38 pubmed publisher
    ..Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements...
  31. Narayanan M, Owers Bradley J, Beardsmore C, Mada M, Ball I, Garipov R, et al. Alveolarization continues during childhood and adolescence: new evidence from helium-3 magnetic resonance. Am J Respir Crit Care Med. 2012;185:186-91 pubmed publisher
    ..The current hypothesis that human pulmonary alveolarization is complete by 3 years is contradicted by new evidence of alveolarization throughout adolescence in mammals...
  32. Rice W, Van Hoek A, Paunescu T, Huynh C, Goetze B, SINGH B, et al. High resolution helium ion scanning microscopy of the rat kidney. PLoS ONE. 2013;8:e57051 pubmed publisher
    b>Helium ion scanning microscopy is a novel imaging technology with the potential to provide sub-nanometer resolution images of uncoated biological tissues. So far, however, it has been used mainly in materials science applications...
  33. García Alcantara E, López Callejas R, Morales Ramírez P, Peña Eguiluz R, Fajardo Muñoz R, Mercado Cabrera A, et al. Accelerated mice skin acute wound healing in vivo by combined treatment of argon and helium plasma needle. Arch Med Res. 2013;44:169-77 pubmed publisher
    ..In the development of the present study, an argon plasma needle was chosen for coagulation purposes, whereas for healing purposes, a helium plasma needle was used.
  34. Morales Ramirez P, Cruz Vallejo V, Peña Eguiluz R, López Callejas R, Rodríguez Méndez B, Valencia Alvarado R, et al. Assessing cellular DNA damage from a helium plasma needle. Radiat Res. 2013;179:669-73 pubmed publisher
    ..Mouse leukocytes embedded in agarose were exposed to the plasma at two different distances from a helium plasma needle outlet and during three different exposure periods...
  35. Kirby M, Mathew L, Heydarian M, Etemad Rezai R, McCormack D, Parraga G. Chronic obstructive pulmonary disease: quantification of bronchodilator effects by using hyperpolarized ³He MR imaging. Radiology. 2011;261:283-92 pubmed publisher
    To evaluate short-acting bronchodilator effects in chronic obstructive pulmonary disease (COPD) by using hyperpolarized helium 3 (³He) magnetic resonance (MR) imaging, spirometry, and plethysmography.
  36. Denifl S, Zappa F, Mähr I, Mauracher A, Probst M, Urban J, et al. Ionization of doped helium nanodroplets: complexes of C60 with water clusters. J Chem Phys. 2010;132:234307 pubmed publisher
    ..Mass spectra recorded by electron ionization of water-doped helium droplets show that the helium matrix also fails to quench OH loss...
  37. Boden S, Asadollahbaik A, Rutt H, Bagnall D. Helium ion microscopy of Lepidoptera scales. Scanning. 2012;34:107-20 pubmed publisher
    In this report, helium ion microscopy (HIM) is used to study the micro and nanostructures responsible for structural color in the wings of two species of Lepidotera from the Papilionidae family: Papilio ulysses (Blue Mountain Butterfly) ..
  38. Staffieri F, Bauquier S, Moate P, Driessen B. Pulmonary gas exchange in anaesthetised horses mechanically ventilated with oxygen or a helium/oxygen mixture. Equine Vet J. 2009;41:747-52 pubmed
    ..It is unknown whether administration of gas-mixtures high in inspired fraction of oxygen (FiO2) under general anaesthesia may increase formation of pulmonary atelectasis and impair gas exchange...
  39. Leino M, Viel A, Zillich R. Electronically excited rubidium atom in helium clusters and films. II. Second excited state and absorption spectrum. J Chem Phys. 2011;134:024316 pubmed publisher
    Following our work on the study of helium droplets and film doped with one electronically excited rubidium atom Rb(?) ((2)P) [M. Leino, A. Viel, and R. E. Zillich, J. Chem. Phys...
  40. Jolliet P, Tassaux D, Thouret J, Chevrolet J. Beneficial effects of helium:oxygen versus air:oxygen noninvasive pressure support in patients with decompensated chronic obstructive pulmonary disease. Crit Care Med. 1999;27:2422-9 pubmed
    ..decompensated chronic obstructive pulmonary disease (COPD), noninvasive pressure support ventilation using 70:30 helium:oxygen instead of 70:30 air:oxygen could reduce dyspnea and improve ventilatory variables, gas exchange, and ..
  41. Kauczor H, Markstaller K, Puderbach M, Lill J, Eberle B, Hanisch G, et al. Volumetry of ventilated airspaces by 3He MRI: preliminary results. Invest Radiol. 2001;36:110-4 pubmed
    ..To develop a validated post-processing routine for volumetry of the ventilated airspaces by 3He MRI...
  42. Pecchiari M, Pelucchi A, D Angelo E, Foresi A, Milic Emili J, D Angelo E. Effect of heliox breathing on dynamic hyperinflation in COPD patients. Chest. 2004;125:2075-82 pubmed
    ..b>Helium-oxygen mixtures (ie, heliox) have been used in treating these patients on the assumption that, by lowering airway ..
  43. Hyldegaard O, Kerem D, Melamed Y. Effect of combined recompression and air, oxygen, or heliox breathing on air bubbles in rat tissues. J Appl Physiol (1985). 2001;90:1639-47 pubmed
    ..The clinical implication of these findings might be that heliox 50:50 is the mixture of choice for the treatment of decompression sickness...
  44. Salerno M, de Lange E, Altes T, Truwit J, Brookeman J, Mugler J. Emphysema: hyperpolarized helium 3 diffusion MR imaging of the lungs compared with spirometric indexes--initial experience. Radiology. 2002;222:252-60 pubmed
    To quantitatively evaluate hyperpolarized helium 3 ((3)He) diffusion magnetic resonance (MR) images of the lung in patients with emphysema and to determine whether apparent diffusion coefficients (ADCs) measured with MR imaging correlate ..
  45. Deninger A, Mansson S, Petersson J, Pettersson G, Magnusson P, Svensson J, et al. Quantitative measurement of regional lung ventilation using 3He MRI. Magn Reson Med. 2002;48:223-32 pubmed
    A new strategy for a quantitative measurement of regional pulmonary ventilation using hyperpolarized helium-3 (3He) MRI has been developed. The method employs the build-up of the signal intensity after a variable number of (3)He breaths...
  46. Berkenbosch J, Grueber R, Dabbagh O, McKibben A. Effect of helium-oxygen (heliox) gas mixtures on the function of four pediatric ventilators. Crit Care Med. 2003;31:2052-8 pubmed
    To evaluate the effects of helium on the function of four ventilators commonly used in pediatrics: the Bird VIP, Bird VIP Gold, Servo 300, and Servo 900C.
  47. Dedieu D, Balon N, Weiss M, Risso J, Kinkead R, Rostain J. Microdialysis study of striatal dopaminergic dysfunctions induced by 3 MPa of nitrogen- and helium-oxygen breathing mixtures in freely moving rats. Brain Res. 2004;998:202-7 pubmed
    Previous studies have demonstrated opposite effects of high-pressure helium and nitrogen on extracellular dopamine (DA) levels, which may reflect disturbances on the synthesis, release or metabolic mechanisms...
  48. Stavngaard T, Søgaard L, Mortensen J, Hanson L, Schmiedeskamp J, Berthelsen A, et al. Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease. Eur J Nucl Med Mol Imaging. 2005;32:448-57 pubmed
    ..The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers...
  49. Tiggesbäumker J, Stienkemeier F. Formation and properties of metal clusters isolated in helium droplets. Phys Chem Chem Phys. 2007;9:4748-70 pubmed
    The unique conditions forming atomic and molecular complexes and clusters using superfluid helium nanodroplets have opened up an innovative route for studying the physical and chemical properties of matter on the nanoscale...
  50. Yablonskiy D, Sukstanskii A, Woods J, Gierada D, Quirk J, Hogg J, et al. Quantification of lung microstructure with hyperpolarized 3He diffusion MRI. J Appl Physiol (1985). 2009;107:1258-65 pubmed publisher
  51. Katz A, Gentile M, Craig D, Quick G, Cheifetz I. Heliox does not affect gas exchange during high-frequency oscillatory ventilation if tidal volume is held constant. Crit Care Med. 2003;31:2006-9 pubmed
    ..We hypothesized that when tidal volume delivery is held constant, heliox does not alter gas exchange...
  52. de Lange E, Altes T, Patrie J, Parmar J, Brookeman J, Mugler J, et al. The variability of regional airflow obstruction within the lungs of patients with asthma: assessment with hyperpolarized helium-3 magnetic resonance imaging. J Allergy Clin Immunol. 2007;119:1072-8 pubmed
    ..With hyperpolarized helium-3 magnetic resonance (H(3)HeMR) imaging, the airspaces are depicted and focal areas of airflow obstruction are ..
  53. Briseno Marroquin B, Kremers L, Willershausen Zönchen B, Mücke A. Microleakage of gold casting repairs with different materials as quantified by a helium gas system. Oper Dent. 1995;20:197-203 pubmed
    ..Tetric, Charisma, and Polofil Molar), and one glass-ionomer cement (Ketac Silver) and gold cast crowns using a helium gas microleakage method...