title: Effect of adhesive drying time on the bond strength of irreversible hydrocolloid to stainless steel.
abstract: BACKGROUND
  The efficacy of adhesive material is believed to be affected by the drying time allowed. However, there is no universal consensus on the drying time required for adhesive to achieve optimal bond strength for irreversible hydrocolloid impressions.
  
  
  OBJECTIVE
  This study investigated the effect of drying time on the cleavage bond strength of irreversible hydrocolloid adhesive and determined optimal adhesive drying time.
  
  
  METHODS
  In the cleavage test, the adhesive bond was stressed at the edge. An offset tensile force was applied to 1 side of the testing plates to split the bond. Cleavage testing plates were designed and machined in stainless steel. Adhesive material (Fix) was applied thinly to the plates and allowed to dry for 1, 3, 5, 7.5, 10, and 20 minutes before loading with an irreversible hydrocolloid (Blueprint). The irreversible hydrocolloid was then allowed to set for 5 minutes before testing. Twenty specimens were tested for each selected drying time. The force at failure was measured by an Instron machine with a crosshead speed of 50 mm/min applied to the edge of the bond. A nonadhesive group was included as a control.
  
  
  RESULTS
  The calculated cleavage bond strength at 1-minute drying (32 kPa) improved moderately up to 5-minute drying (37 kPa), but decreased on further drying. When compared with specimens in the nonadhesive group, cleavage bond strength was 3 times greater when the adhesive was applied and dried for 5 minutes.
  
  
  CONCLUSIONS
  Adhesive is effective in improving the cleavage bond strength of irreversible hydrocolloid to stainless steel, and drying of adhesive in excess of 5 minutes is not recommended.
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Hong Kong. kcmleung@hkucc.hku.hk
authors.forename: K C
authors.initials: KC
authors.lastname: Leung
authors.forename: T W
authors.initials: TW
authors.lastname: Chow
authors.forename: E C
authors.initials: EC
authors.lastname: Woo
authors.forename: R K
authors.initials: RK
authors.lastname: Clark
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000269:Adhesives / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry*; D000704:Analysis of Variance; D003102:Colloids / Q000737:chemistry*; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D009757:Nylons / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014992:Xylenes / Q000737:chemistry
chemical_list: D000269:Adhesives; D000464:Alginates; C062271:Blueprint Asept; D003102:Colloids; D009757:Nylons; D012997:Solvents; D014992:Xylenes; D013193:Stainless Steel; D019840:2-Propanol