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

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.