Susceptibility of a polycaprolactone-based root canal filling material to degradation. I. Alkaline hydrolysis

Polycaprolactone, a thermoplastic aliphatic polyester, is reportedly susceptible to both alkaline and enzymatic hydrolyzes. This screening study examined the susceptibility of Resilon, a polycaprolactone-based root filling composite, to alkaline hydrolysis. There were 15-mm diameter disks of Resilon and Obtura gutta-percha prepared by compressive molding and immersed in 20% sodium ethoxide for 20 or 60 min. Control disks were immersed in ethanol for 60 min. These disks were examined using field-emission scanning electron microscopy and energy dispersive X-ray analysis. For Resilon, the surface resinous component was hydrolyzed after 20 min of sodium ethoxide immersion, exposing the spherulitic polymer structure and subsurface glass and bismuth oxychloride fillers. More severe erosion occurred after 60 min of sodium ethoxide treatment. Gutta-percha was unaffected after immersion in sodium ethoxide. As Resilon is susceptible to alkaline hydrolysis, it is possible that enzymatic hydrolysis may occur. Biodegradation of Resilon by bacterial/salivary enzymes and endodontically relevant bacteria warrants further investigation.