Reverse Engineering Utilizing the 3D Photogrammetry Technique Versus Commercial Scanners for Accurate Repositioning of the Maxilla After Le-fort I Osteotomy for Correction of the Dentofacial Deformity (Randomized Controlled Clinical Trial).

In orthognathic surgery, the precise repositioning of the maxilla after Le-fort I osteotomy is a challenging procedure because there is no room for error in this step if the procedure is to be accurate.Transferring the virtual position of the maxilla to the real operative field via the intermediate occlusal splint fabrication, which is the most commonly used method, ensures only the intended position of the maxilla in the transverse, sagittal planes and cannot guarantee its vertical position in relation to the skull base. The vertical maxillary repositioning usually relies on a manual intraoperative adjustment using either intra-oral or extraoral reference points and affected by the degree of autorotation of the mandible that occur as a result of the surgical maneuvers operated by the surgeon intraoperatively. This makes the reliability of and precision in transferring virtual surgical plans to the operative field is still unpredictable defeating the main advantages of 3D technology. Moreover, it can be time consuming.

Many attempts to obtain a more reliable method for positioning the maxilla, independent of the mandible, have been made such as a series of maxillary reposition templates, patient specific osteosynthesis plates and navigation assisted surgery and it yielded satisfactory results. Also, intraoperative occlusal-based devices that transfer virtual surgical planning to the operating field for repositioning of the osteotomized segments was introduced. Most of the time the surgeon looks for new modalities to optimize his surgical results, simplify the execution of the surgery and at the same time to meet the patients' demands and expectations.

Photogrammetry is a versatile, readily available technique that allows for creating a 3D model from 2D photographs in an affordable manner and with a high levels of precision equivalent to other tools that are generally more expensive and less available such as a commercial scanner. It has several applications in the life and earth sciences, medicine, osteological studies, architecture, topography, archaeology, crime scene investigation, cinematography, and engineering. So, the present study aims to assess the accuracy gained and the feasibility of using this technique for transferring the virtually intended maxillary segment position to the real operation compared with the commercial scanners.

Trial design:

Randomized Controlled Clinical Trial. Parallel group, two arm with allocation ratio 1:1.