Comparative analysis of tensile strength between three types of retraction cords

Abstract

Introduction: Gingival retraction is the withdrawal of the marginal gingiva away from the tooth. This procedure creates a space between the prepared tooth and the gingival tissues to catch more fine details of the impression material. The most common retraction device used in clinical practice is the retraction cord. Aim: The study aims to evaluate the tensile strength of retraction cords designed with different braiding technology. Materials and methods: A total of 150 experimental units were studied. They were divided into 3 groups of 50 each according to the type of retraction cord (Ultrapak #00, braided cord without core, and braided cord with monofilament core). We tested the tensile strength in the LMT 100 micro-tensile apparatus. The data were analyzed using SPSS v. 21. A critical significance level of p<0.05 is used. Results: The comparative analysis of the tensile strength of the retraction cords shows a statistically significant difference between the braided and the knitted threads (Ultrapak #00) (p<0.001). The results indicated the highest tensile strength of the cord with monofilament 41.95 N/mm2, followed closely by the cord with the same cotton braid without monofilament with average strength of 39.80 N/mm2, and last came the Ultrapak cord 22.11 N/mm2. Conclusions: The braided retraction cords show higher tensile strength compared to the Ultrapak #00 cord, which is made using knitting technology.