Quantitative Assessment of Physical Changes in Facial Soft Tissue Caused by Personalized 3d-Printed Peek Implants

PEEK (polyether ether ketone) has been used as a biocompatible material for implant development for several decades and with more recent advances in technology such implants now can also be manufactured by 3D printing. Due to this manufacturing process, such implants currently are limited to non-load bearing use, therefore being applicable for cosmetic surgeries, primarily for patients that have undergone trauma or disease which has impacted their bony tissue and led to unwelcome visual changes. As the aim of these type of procedures is to improve the aesthetic outcome, which more often than not is dictated by the visible soft tissue, it is paramount to understand the impact of the implant design itself, as the current approaches primarily focus on the correction of hard tissue defects at its core. To examine this, a total of four patients, each with at least one presonalised and 3D-printed PEEK implant used for facial correction in a different area (orbit, cheek, mandible and maxilla) had a CBCT (cone-beam computed tomography) scan taken before and approximately 6 months after surgery. These examinations were superimposed and then used to identify changes in the soft tissue volume, skin surface area and the total soft tissue thickness at the site of the implant. The change in soft tissue volume and the skin surface area varied only by up to 5% when compared to the implants volume and the surface area in contact with the soft tissue interface, respectively, in the majority of cases, while the total soft tissue thickness on average changed by a value equivalent to half of the implant thickness. These preliminary findings indicate, that while the current implant design process may lead to the desired outcome in improving the aesthetic of the patient, the soft tissue changes do not seem to be uniform, therefore implying that the implant design process could be improved by further understanding its relationship with the corresponding soft tissue response.