title: Usefulness of a rotation-revolution mixer for mixing powder-liquid reline material.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the distribution of bubbles, degree of mixing, flowability and mechanical strength of powder-liquid reline material by manually and with a rotation-revolution (planetary) mixer, and to determine the usefulness of a rotation-revolution mixer for this application.
  
  
  METHODS
  Powder-liquid reline material (Mild Rebaron, GC, Tokyo, Japan) was mixed with a powder to liquid ratio of 1:0.62 according to the manufacturer's instruction. Two methods were used to mix it: mixed by manually ("manual-mixing") and automatically with a rotation-revolution mixer (Super Rakuneru Fine, GC, Tokyo, Japan; "automatic-mixing"). Disc-shaped specimens, 30 mm in diameter and 1.0mm in thickness, were used to observe the distribution of bubbles in at 10× magnifications. Flowability tests were carried out according to the JIS T6521 for denture base hard reline materials. A three point bending test was carried out by a universal testing machine. Elastic modulus and flexural stress at the proportional limit were calculated.
  
  
  RESULTS
  A median of 4 bubbles and inhomogeneous were observed in manual-mixed specimens. However, no bubbles and homogeneous were observed in automatic-mixed specimens. Flowability was within the JIS range in all mixing conditions and did not differ significantly across conditions. The elastic modulus was the same for manual-mixed and automatic-mixed specimens. On the other hand, the flexural stress at the proportional limit differed significantly between manual-mixed and automatic-mixed specimens.
  
  
  CONCLUSIONS
  The results confirm that rotation-revolution mixer is useful for mixing powder-liquid reline material. Automatic-mixing may be recommended for clinical practice.
authors.affiliation: Division of Comprehensive Prosthodontics, Niigata University, Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-Dori, Niigata 951-8126, Japan. Electronic address: y.yamaga@dent.niigata-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamaga
authors.affiliation: Division of Biomimetics, Niigata University, Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-Dori, Nigata 951-8126, Japan.
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Kanatani
authors.affiliation: Professor Emeritus, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nomura
mesh_terms: D003764:Dental Materials / Q000737:chemistry; D003799:Dental Stress Analysis / Q000379:methods; D003819:Denture Bases; D003822:Denture Liners; D008422:Materials Testing / Q000379:methods; D055585:Physical Phenomena; D011208:Powders; D012399:Rotation; D013674:Technology, Dental / Q000295:instrumentation* / Q000379:methods
chemical_list: D003764:Dental Materials; D011208:Powders
keywords: Direct denture reline; Powder–liquid reline material; Rotation–revolution mixer