Comparing suture strengths for clinical applications: a novel in vitro study

Abstract

Background: The purpose of this study was to compare the tensile strengths of commonly used sutures over a 2-week period under simulated oral conditions.

Methods: Three suture materials (chromic gut [CG], polyglactin [PG], and polyglactin-fast absorbing [PG-FA]) were used in 4-0 and 5-0 gauges. After pretensioning, 252 suture samples (42 of each material and gauge) were used. A biologic simulation was created in vitro by mixing 9 ml sterile human saliva and human serum in a 1:1 ratio in a petri dish maintained at a pH of 7.4 to 8.1 at 37 degrees C. All samples were tested preimmersion and 1 hour and 1, 3, 7, 10, and 14 days postimmersion. The tensile strength was assessed using a microtensile tester, and the maximum load required to cause suture breakage was determined. The point of breakage in the samples and the samples themselves were also assessed.

Results: During the first 24 hours of immersion, all 4-0 and 5-0 samples of CG and PG maintained their initial level of tensile strength; PG-FA 5-0 decreased in strength, which was statistically significant (P = 0.001). Between days 1 and 3, the tensile strength of PG and PG-FA decreased significantly, with PG-FA 5-0 showing a greater and more precipitous decrease than PG-FA 4-0; the tensile strength of CG changed little during this time. After 7 days of immersion, PG 4-0 had significantly greater tensile strength than CG, and both were significantly greater than that of PG-FA. By day 10, CG and PG had statistically greater strength (P = 0.01) than PG-FA, and values were similar for the 4-0 and 5-0 gauge materials. All samples of PG-FA 5-0 and most samples of the PG-FA 4-0 exhibited 0.00 N strength (i.e., they had disintegrated) at the 10- and 14-day periods of evaluation.

Conclusions: 4-0 sutures are stronger and have greater tensile strength than 5-0 sutures. CG seems to sustain its strength better than PG and PG-FA after 2 weeks. PG-FA may not be a desirable suture if tensile strength is required after 10 days. Appropriately designed clinical studies are necessary to confirm this finding in an in vivo environment.