Three-dimensionally printed polycaprolactone shows more physiological stiffness compared with titanium alloy

Introduction

Intraoral bone regeneration requires the use of meshes made of titanium alloy (Ti6Al4V) placed under the oral mucosa as space maintainers and with adequate stiffness to withstand chewing loads. However, excessive load resistance could damage the mucosa with the exposure of meshes and infectious problems. Also, polycaprolactone (PCL), a resorbable polymer, is used as a mesh because it has high hardness at physiological temperatures. Both Ti6Al4V and PCL need to be sterilized before use. The objectives of this study are to compare the response to mechanical load between sterile PCL (SPCL), virgin PCL (VPCL) and Ti6Al4V meshes.

Methods

Fifteen meshes with dimensions of 10 mm x 30 mm were designed with free CAD software; thickness was 0.2 mm for five Ti6Al4V meshes and 0.8 mm for ten PCL meshes. The meshes were produced with selective laser melting for Ti6Al4V and a fused deposition modeling for PCL. Before loading, five PCL meshes were sterilized in a laminar flow hood using ethanol solution (70%) for 30 minutes, washed in distilled water for 10 minutes and then left to air-dry. All meshes were fixed at four points at the ends and loaded centrally with a universal testing machine (MTS 810) running at 130N and a 10 mm/min speed using a spherical point measuring 10 mm in diameter until the first failure.

Results

The first failure of VPCL and SPCL appeared at 46 ± 1.74 N and 36 ± 3,83 N, respectively, while it appeared at 83,1 ± 19,97 N for Ti6Al4V. PCL showed low stiffness compared with Ti6Al4V (2,8 ± 0,67, 2,0 ± 0,19 and 9,4 ± 2,11 N/mm for VPCL, SPCL, and Ti6Al4V, respectively).

Conclusions

Ti6Al4V displays higher stiffness compared with PCL, but the latter is more than adequate for withstanding physiological chewing loads and as a space maintainer. Furthermore, the PCL stiffness values ​​are similar to those of keratinized mucosa reported in the literature.