title: [Influence of hand-mixed methods on compressive strength of zinc phosphate dental cement].
abstract: OBJECTIVE
  To study the influence of hand-mixed methods on the compressive strength of the zinc phosphate dental cement.
  
  
  METHODS
  Three skilled nurses used three kinds of common clinical hand-mixed methods (included the unidirectional rotation method, the alternate pro and con bidirectional rotation method and the pulling and pushing with folding method) to mix the zinc phosphate dental cement on the same condition (i.e. same indoor temperature and humidity, the same mixing ratio, mixing time, mixing frequency and the same mixing instruments and so on). The mixed zinc phosphate cement was packed into the plastic cylinders with 10 mm-high and 5 mm-bore. After the mixed zinc phosphate cement coagulated, compressive strength was tested separately.
  
  
  RESULTS
  The compressive strength of the zinc phosphate dental cement mixed with the alternate pro and con bidirectional rotation method was the best, and the value was (106.11+/- 4.82) MPa. The compressive strength of the zinc phosphate dental cement mixed with the pulling and pushing with folding method was lower, and the value was (77.57 +/- 6.26) MPa. The compressive strength of the zinc phosphate dental cement mixed with the unidirectional rotation method was the lowest, and the value was (54.41 +/- 5.08) MPa. The compressive strength of the zinc phosphate dental cement mixed with the unidirectional rotation method and the pulling and pushing with folding method could not achieve the clinical required compressive strength (about 100 MPa), while the compressive strength mixed with the alternate pro and con bidirectional rotation method was above 100 MPa.
  
  
  CONCLUSIONS
  The alternate pro and con bidirectional rotation method to mix the zinc phosphate dental cement is recommended in clinic.
authors.affiliation: Department of Conservative Dentistry and Endodontics, West China College of Stomatology, Sichnan University, Chengdu 610041, China.
authors.forename: Hao-Lai
authors.initials: HL
authors.lastname: Li
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Bi
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Li
authors.forename: Wen
authors.initials: W
authors.lastname: Chen
authors.forename: Xiao-Xi
authors.initials: XX
authors.lastname: Zhao
authors.forename: Jin-Bo
authors.initials: JB
authors.lastname: Yang
mesh_terms: D019245:Compressive Strength; D010710:Phosphates; D017967:Zinc Compounds; D015036:Zinc Phosphate Cement
chemical_list: D010710:Phosphates; D017967:Zinc Compounds; C043952:zinc phosphate; D015036:Zinc Phosphate Cement