OBJECTIVES: The objectives of this study were to investigate the compositions, pattern of weaving and some physical properties (swelling, tensile strength) of six gingival retraction cords. METHODS: Types of cord fiber were identified using TISI 121 book 15:1981 and AATCC 20:2004 techniques. Pattern of weaving and number of threads were observed using light microscope. Ten cords of each brand were used to measure the amount of swelling after immersion in distilled water for 5 and 10 minutes. Two hundred and twenty specimens were divided into eleven groups for tensile testing, 20 samples for each group (10 centimeters in length). The strength tests were performed in dry and wet conditions using a universal testing machine at cross-head speed of 100 mm min-1. RESULTS: The chemical analysis showed that three gingival retraction cords were made from cotton. Other two brands were cotton-polyester and cotton-nylon-copper cords. One brand was made of polyester. Most cords were braided. The gingival retraction cords used in this study could be divided into two groups according to their diameters. In group 1, the cord diameters ranged between 0.58-0.68 mm. In group 2, the cord diameter ranged between 0.76-0.86 mm. Maximum swelling percentage of cords were 13.1% (cotton fiber) in group 1 and 15.1% (polyester fiber) in group 2. The retraction cords made from polyester exhibited the highest tensile strength in both groups and were significantly different from the others. There was no statistically significant difference between the tensile strengths of dry and wet cords for most of the retraction cords tested. CONCLUSIONS: Most gingival retraction cords were made from cotton. The amount of swelling and tensile strengths of gingival retraction cords depended on the fiber composition and diameter. Polyester retraction cords exhibited the highest strength.

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