Susceptibility of a Polycaprolactone-Based Root Canal Filling Material to Degradation. I. Alkaline Hydrolysis

Abstract

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.

Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction

“…12 In addition, the thermoplasticity of Resilon is higher than that of conventional and thermoplastic gutta-percha. 19 The thermoplastic properties of Resilon are attributed to the addition of polycaprolactone, which has a melting point of 60°C, 28 making it indicated for thermoplastic obturation techniques. 5,15,19 Gutta-percha cones are composed of barium sulfate, zinc oxide, wax, resin and gutta-percha, but the proportions of these components are not constant.…”

Root canal filling using Resilon: a review

“…97 All these in vitro leakage studies are evaluated over a number of days or weeks and it has been suggested that this may give a false perspective of the behaviour of resin sealers as they may degrade 88 or hydrolysis with time. 35,98 Therefore, before any meaningful conclusions can be made long-term evaluations and clinical studies are necessary.…”

“…104 It was suggested that a reason for Resilon's potential cytotoxicity may be due to the biodegradability of Resilon by enzymes and alkaline hydrolysis, which would expose the more toxic polymer matrix. 36,98 Epiphany sealer has been shown to be cytotoxic when compared to zinc oxide eugenol and epoxy-resin based sealers 100,105-110 with one study suggesting that it became more cytotoxic with increased exposure time. 111 However, it has also been demonstrated that although Epiphany was cytotoxic it did not effect the viability of human leucocytes.…”

“…36,98 This biodegradation may result in the leaching of dyes from the material. The formation of a precipitate and associated colour change has also been noted when Resilon is disinfected with 2% chlorohexidine.…”

Resilon: A Comprehensive Literature Review

“…6 One study examined susceptibility of Resilon and gutta-percha to microbial biodegradation and showed minimal changes in the surface integrity of gutta-percha; however, Resilon exhibited severe surface pitting and erosion. 7 …”