Four-Dimensional Imaging of Soft Tissue and Implanted Biomaterial Mechanics: A Barbed Suture Case Study for Tendon Repair.

Timely, recent developments in X-ray microcomputed tomography (XµCT) imaging such as increased resolution and improved sample preparation enable nondestructive time-lapse imaging of polymeric biomaterials when implanted in soft tissue, which we demonstrate herein. Imaging the full three-dimensional (3D) structure of an implanted biomaterial provides new opportunities to assess the micromechanics of the interface between the implant and tissues and how this changes over time as force is applied in load-bearing musculoskeletal applications. In this paper, we present a case study demonstrating in situ XµCT and finite element analysis, using a dynamically loaded barbed suture repair for its novel use in tendon tissue. The aim of this study was to identify the distribution of stress in the suture and tendon as load is applied. The data gained demonstrate a clear 3D visualization of microscale features in both the tissue and implant in wet conditions. XµCT imaging has revealed, for the first time, pores around the suture, preventing full engagement of all the barbs with the tendon tissue. Subsequent finite element analysis reveals the localized stress and strain, which are not evenly distributed along the suture, or throughout the tissue. This case study demonstrates for the first time a powerful in situ mechanical imaging tool, which could be readily adapted by other laboratories to interrogate and optimize the interface between the implanted biomaterials and the soft tissue.

Micro-CT evaluation of the effectiveness of the combined use of rotary and hand instrumentation in removal of Resilon.

This study compares the effectiveness of ProTaper rotary files with ProTaper retreatment and K-files in the removal of Resilon or gutta percha (GP) from canals filled either by cold lateral condensation or thermal obturation using micro-CT. Ninety-six teeth were prepared using ProTaper files and allocated into four groups (n=24): Group-1 was filled with GP/AH-Plus and Group-2 with Resilon/RealSeal using cold lateral condensation. Group-3 was filled with GP/AH-Plus and Group-4 with Resilon/RealSeal using System B and Obtura II. The roots were scanned by micro-CT. Each group was divided into two subgroups (n=12): A, retreated using ProTaper files and B, using ProTaper retreatment and K-files. The roots were scanned to calculate the volume of the remaining material. With thermal obturation, roots filled with Resilon had significantly more remaining material than GP. Obturation using thermal technique resulted in significantly less remaining material than cold condensation except Resilon retreated using ProTaper retreatment and K-files.