Novel patient-specific helical maxillary distractor: an in vitro feasibility study.

At present, stock linear distractors are used for internal maxillary distraction osteogenesis. However, the authors' research group has demonstrated, through an in silico analysis, that linear distraction leads to bone deformities and malocclusion, whereas helical distraction can yield ideal outcomes. A system for designing and manufacturing custom helical distractors has recently been developed, and the feasibility of these appliances now needs to be assessed. This study was, therefore, conducted to gain an initial insight into their feasibility. The study had two goals. First, it aimed to demonstrate, in an in vitro model, that the novel system of custom helical distraction can produce appropriate clinical outcomes. The second aim was to compare the performance of custom helical distractors with that of stock devices and hybrid devices (i.e., linear appliances that feature patient-specific footplates). Interpreting the results as trends, this study showed that the system of custom helical distraction resulted in in vitro outcomes that were superior to those obtained with stock and hybrid devices.

A new patient-specific helical maxillary distractor: a cadaver test.

The primary objective of this cadaver study was to assess the feasibility of a novel custom helical distraction system and a patient-specific antral maxillary distractor. The study involved two fresh cadaver heads and followed a systematic procedure. First, virtual planning was conducted for an asymmetric maxillomandibular advancement. Custom patient-specific hardware was then fabricated to enable sequential mandibular advancement and gradual maxillary distraction. The mandibular lengthening procedures were found to be highly accurate, with only minor deviations from the planned results. In terms of maxillary distraction, the patient-specific antral distractors demonstrated favorable outcomes, with two noteworthy exceptions. Ideal forward maxillary advancement was short by a modest 2-3 mm in both cadavers. Additionally, cadaver 2 exhibited an unplanned pitch malrotation. However, an excellent occlusion was achieved in cadaver 1 and an acceptable anterior occlusion in cadaver 2, albeit with bilateral posterior open bites that could be readily corrected with interdental elastics in a clinical setting. This cadaver model study provides compelling evidence for the feasibility of patient-specific antral helical distractors, highlighting their potential to yield positive outcomes. Importantly, the study results suggest that patient-specific antral distractors may offer superior results compared to the current standard of linear distractors.

Predicting optimal patient-specific postoperative facial landmarks for patients with craniomaxillofacial deformities.

Orthognathic surgery primarily corrects skeletal anomalies and malocclusion to enhance facial aesthetics, aiming for an improved facial appearance. However, this traditional skeletal-driven approach may result in undesirable residual asymmetry. To address this issue, a soft tissue-driven planning methodology has been proposed. This technique estimates bone movements based on the envisioned optimal facial appearance, thereby enhancing surgical accuracy and effectiveness. This study investigates the initial implementation phase of the soft tissue-driven approach, simulating the patient's ideal appearance by realigning distorted facial landmarks to an ideal state. The algorithm employs symmetrization and weighted optimization strategies, aligning projected optimal landmarks with standard cephalometric values for both facial symmetry and form, which are essential in orthognathic surgery for facial aesthetics. It also incorporates regularization to preserve the patient's facial characteristics. Validation through retrospective analysis of preoperative patients and normal subjects demonstrates this method's efficacy in achieving facial symmetry, particularly in the lower face, and promoting a natural, harmonious contour. Adhering to soft tissue-driven principles, this novel approach shows promise in surpassing traditional methods, potentially leading to enhanced facial outcomes and patient satisfaction in orthognathic surgery.