Analysis of Resident Time Spent in Traditional Versus Virtual Treatment Planning for Orthognathic Surgery

Virtual treatment planning (VTP) software allows the surgeon to predict complex orthognathic surgical movements in 3-dimensions (3-D) prior to executing the plan in the operating room. Recent advances in 3D printing technology have made it possible to fabricate surgical guides based on CT data rather than making them manually on stone dental models. Potential advantages of VTP include: improved understanding of the underlying pathologic and three dimensional anatomy and improved splint construction when compared to  standard methods. Another potential benefit is a reduction in time spent by the surgeon, preoperatively, in the dental laboratory. The purpose of this study is to compare the time required for preoperative planning and model surgery by the standard technique versus VTP.   We hypothesize that there is a significant reduction in laboratory time with VTP.

                This was a prospective study of orthognathic surgery planning done at Massachusetts General Hospital (MGH) from January 2014 through January  31,  2015.  Inclusion criteria included bimaxillary cases where  both standard and VTP planning were used.  Workflow data was collected, dividing it into 3 parts.  Part 1 included time required for history and clinical examination, impressions, obtaining facebow mounting, pouring and trimming models, surveying models and preparation for model surgery.  Part 2 involved steps performed by the surgeon  to execute the plan in the operating room: occlusal grinding and bite analysis, model surgery and traditional splint fabrication (2 splints per case, final and intermediate). The sum of times spent in Parts 1 and 2 corresponds to traditional treatment planning.   Part 3 included time for an online VTP session with Materialise (Plymouth, MI) engineers.  The sum of times spent on Parts 1 and  3 corresponds to  VTP.  The time required for a CT scan, occlusal model scan, mapping of orthognathic reference points, 3-D model preparation and 3-D printing of the splints performed by Materialisetechnicians was not included in the surgeons’ time for VTP.   Average times were collected and analyzed for each step in the workflow. Comparison of the accuracy of fabricated splints was not analyzed in this study.

                There were 42 bimaxillary cases that met the inclusion criteria for this study: 21  asymmetry, 18 symmetric and 7 segmental LeFort I osteotomy cases. Average total time spent on the process for Part 1 was 4.43 hrs and for Part 2, 3.08 hrs.  Average VTP session time (Part 3) was 0.67 hours.  Average surgeons’ time required for traditional treatment planning, Part 1 plus Part 2 was 7.48 hours versus average  time required for VTP (Part 1 plus Part 3) of 4.27 hrs,  a  47.6% (p<.001) time reduction.   VTP fabricated splints were noted to fit well and were used in all cases except for one final splint.

                The results of this prospective study indicate that VTP reduces total time for treatment planning of bimaxillary  and asymmetry cases by 47 % when compared to standard surgical planning. Since part 1 data gathering is the same for both methods, the time saved occurs in the elimination of (part 2) the preparation  and execution of model surgery and construction of splints by hand rather than by 3-D printing.

References:

Stokbro K, Aagaard E, Torkov P, Bell RB, Thygesen T. Virtual planning in orthognathic surgery.  Int J Oral Maxillofac Surg. 2014 Aug;43(8):957-65.

Farrell BB, Franco PB, Tucker MR.  Virtual surgical planning in orthognathic surgery. Oral Maxillofac Surg Clin North Am. 2014 Nov;26(4):459-73.