title: In vitro kinetic study of absorbency of retraction cords.
abstract: BACKGROUND
  The soaking time required for liquid uptake by retraction cords is a crucial factor in the successful gingival retraction procedure.
  
  
  OBJECTIVE
  The aim of this investigation was to determine the optimal soaking time for 3 retraction cords of different thickness to ensure adequate uptake of the hemostatic solution.
  
  
  METHODS
  Braided ULTRAPAC retraction cords of 3 different thicknesses (No. 00, No. 0, and No. 1) with identical lengths (35 mm) were used. The capability of the cords to absorb liquids was measured by a gravimetric method. Different sulcus retraction solutions (epinephrine, aluminum chloride, and ferric sulfate) were tested, with physiological saline solution used as the control. The cords were soaked for various time intervals (2 seconds; 1, 5, and 60 minutes; and 24 hours) in the medicament solutions at room temperature. Immediately before immersion, air inclusions that may have inhibited the inner moistening of the cords were manually pressed out. In each of the 4 treatment groups, 75 pieces of cord were tested by determining the grams of fluid absorbed by grams of dry cord (gram/gram). Before the cord was weighed, excess fluid accumulating on the outer surface of the cord was removed by filter paper saturated in the corresponding test solution. The data were analyzed by F test analysis, and P<.05 was regarded as significant.
  
  
  RESULTS
  In each group, regardless of the cord type (No. 00, No. 0, or No. 1) or medicament solutions tested, the amount of fluid absorbed increased with the soaking time, but to different extents. A logarithmic relationship in a linear plot between the amount of fluid absorbed and the soaking time was demonstrated. The relationship established offered an exact determination of both the rate and the saturation level of liquid uptake. The rate of liquid uptake calculated from the saturation equations exhibited significant correlation with the cord thickness (P<.05). The saturation levels of the solutions did not show correlation with the cord thickness (P>.30).
  
  
  CONCLUSIONS
  Within the limitations of this study, the results indicated that 20 minutes of soaking time was necessary for saturation of the cords before use, provided that air trapped within the cords was removed. In addition to the soaking time, the saturation of the cords with the solutions largely depended on the wetting of the cords.
authors.affiliation: Faculty of Dentistry, Department of Conservative Dentistry, Semmelweis University, Budapest, Hungary. csempesz@konfog.sote.hu
authors.forename: Ferenc
authors.initials: F
authors.lastname: Csempesz
authors.forename: János
authors.initials: J
authors.lastname: Vág
authors.forename: Arpád
authors.initials: A
authors.lastname: Fazekas
mesh_terms: D000042:Absorption; D000388:Air; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry; D001252:Astringents / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D003761:Dental Impression Technique / Q000295:instrumentation*; D004837:Epinephrine / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D006490:Hemostatics / Q000737:chemistry; D006801:Humans; D007101:Immersion; D016014:Linear Models; D008422:Materials Testing; D012965:Sodium Chloride / Q000737:chemistry; D013223:Statistics as Topic; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000737:chemistry; D017155:Wettability
chemical_list: D017607:Aluminum Compounds; D001252:Astringents; D002712:Chlorides; D005290:Ferric Compounds; D006490:Hemostatics; D014662:Vasoconstrictor Agents; D000077410:Aluminum Chloride; C024823:ferric sulfate; D012965:Sodium Chloride; D004837:Epinephrine