In recent years, patient-specific implants (PSIs) have revolutionized maxillofacial reconstructive surgery, also due to advances in three-dimensional imaging, CAD design, and additive manufacturing. In particular, the use of polyetheretherketone (PEEK) prostheses allows for high biocompatibility and mechanical stability, as well as more predictable aesthetic outcomes. Despite these advantages, the response of facial soft tissues to such implants remains poorly explored and difficult to predict, still representing one of the main challenges in the prediction of surgical outcomes. The purpose of this study was to develop and apply a three-dimensional quantitative analysis pipeline to evaluate the correlation between PSI thickness and the actual augmentation of soft tissues observed in the postoperative phase.