Comparison of feasibility, time consumption and costs of three virtual planning systems for surgical correction of midfacial deficiency

The purpose of this study was to evaluate the usability of three established VSP software applications (IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®) regarding the virtual planning steps of midfacial correction using modified IQLFIIO. Specific aims were to compare feasibility, time consumption, and costs in a standardized workflow.

Based on retrospective data, we performed a cross-sectional study and re-planned all patients with midfacial deficiency treated by modified IQLFIIO and BSSO (bilateral sagittal split osteotomy) at our institution between April 2013 and December 2018 using the three software applications: IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®.

The study sample was recruited from a consecutive series of patients with midfacial deficiency treated by modified IQLFIIO and BSSO. Inclusion criteria were midfacial deficiency and skeletal class III malocclusion as well as a fulfilled protocol with pre-surgical and post-surgical orthodontic treatment. The surgical treatment had to be completed at the time point of the beginning of the study. Exclusion criteria were missing or poor quality of available pre-surgical computer tomography (CT) data.

This study was approved by the ethics committee of the authors’ institution (No. EK 1775/2017) and performed according to the Declaration of Helsinki and the guidelines for Good Clinical Practice (GCP).

In this retrospective study, all cases were re-planned by VSP with three different software application systems. The pre-intervention data were obtained from existing CT or cone-beam CT (CBCT) examinations of the head. VSP was done with the software applications IPS Case Designer ® (KLS Martin Group), Dolphin Imaging ® 11.95 (Patterson Dental Supply, St. Paul, MN), and ProPlan CMF ® (Materialise). A routine workflow for VSP for IQLFIIO was performed. This included data import of Digital Imaging and Communications in Medicine (DICOM) datasets, rendering a 3D image of the head, setting the intervention cut lines for IQLFIIO, calculating the surgical intervention of the 3D model for hard and soft tissue. The last step was virtual model surgery by moving the maxilla including the infraorbital region into the target position.

All VSP were performed with a personal computer—Dell Inspiron 15 5000 Notebook (Intel Core i5-7500 U, 16 GB RAM, 256 GB SSD, AMD Radeon R7 M445) by one experienced person who had been trained on all three applications.

To evaluate and compare feasibility, the following steps in the process of VSP of an IQLFIIO were evaluated: (i) preselect a IQLFIIO tool, (ii) setting of cut lines on defined IQLFIIO landmark positions (maxilla, infraorbital rim, anterior nasal spine), (iii) 3D rendering of the segment to be moved, (iv) act of moving to the target position, and (v) possibility to design a splint.

In order to establish a standardized and realistic procedure, post-surgical intervention results were defined as the target position for the VSP. Distances between pre- and post-operative landmarks were measured in a previous step to import exactly these movements into the VSP system. These data were obtained by image fusion using Materialise Mimics ® Research 21.0 (Mimics-Materialise NV Belgium). These measurements were used to set the target position in all three compared VSP systems.

The IQLFIIO cut lines were set in positions corresponding to the post-operative CT scans. The 3D rendered model was cut exactly along these lines. The selected IQLFIIO part was moved into the target position by manual input of the known distances. All the measurements and VSP have been done by one researcher who has been experienced and trained in using these software tools consequently.

Regarding time used for the VSP, the time of the surgeon working with the PC was measured for all steps of the VSP procedure in minutes (min).

Regarding costs, asset costs for acquiring the software application, license fee, license possibilities, paying for support services, service contracts, and costs for splint production in cooperation with the VSP system were covered by contacting the company. Costs were calculated in dollars ($) without value-added tax.

For characterizing the study, cohort descriptive statistics was used. All data were recorded in Microsoft Excel 2017.

The purpose of this study was to evaluate the usability of three established VSP software applications (IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®) regarding the virtual planning steps of midfacial correction using modified IQLFIIO. Specific aims were to compare feasibility, time consumption, and costs in a standardized workflow.

For the graphical analysis of time consumption, a boxplot graphic was created. For comparison time consumption, a post hoc analysis with a Tukey range test was performed.

Statistical analysis was performed using the open source software R Project R 3.1.1. The costs are outlined in tables.

All evaluated steps of the VSP procedure, including (i) preselect a IQLFIIO tool, (ii) setting and definition IQLFIIO cut lines, (iii) 3D rendering of the segment to be moved, (iv) moving the IQLFIIO part to target position could be successfully tested in all three evaluated applications in all 19 cases.

Differences between the three tested software applications among another were found: (i) Only the system ProPlan CMF ® offers a tool to select Le Fort II osteotomy. A VSP of the IQLFIIO performed with this system is depicted in Fig. 1. In IPS Case Designer ® and Dolphin Imaging ®, only the Le Fort I intervention type for the upper jaw surgery was selectable. (ii) It was possible to manually set the cut lines in the Le Fort II level in the IPS Case Designer ® and Dolphin Imaging ®. When using ProPlan CMF ®, a tool called “Mimics” has to be used prior to planning for rendering and maxillary and mandibular or the whole Midface region segmentation. It is required for setting the surgical cut lines in a second step. (iii) 3D rendering was possible in all three systems. A VSP of the IPS Case Designer ® system is seen in Figs. 2 and 3. (iv) To finish the VSP process, moving the segmented part to the target position was also possible. As well as to visualize soft tissue changes—seen in Fig. 4 (Dolphin Imaging ®). (v) Surgical splint design using with CAD/CAM technology was also possible in all three software applications. An example is given in Fig. 5.

For the VSP system IPS Case Designer ®, the mean value of time needed was 36.5 min (median, 32 min; minimum, 20 min; maximum, 60 min).

For the VSP system Dolphin Imaging ®, the mean value of time needed was 33.6 min (median, 30 min; minimum, 20 min; maximum, 60 min).

For the VSP system ProPlan CMF ®, the mean value of time needed was 45.5 min (median, 43 min; minimum, 25 min; maximum: 63 min).

Also seen in Fig. 6.

To compare the three systems regarding working time, we performed a post hoc analysis. Therefore, a Tukey range test was used. We found a statistical significant difference between ProPlan CMF ® and Dolphin Imaging ® (p value, 0.02). There was no statistical significance found between the IPS Case Designer ® and Dolphin Imaging ® (p value, 0.7) and ProPlan CMF ® and IPS Case Designer ® (p value, 0.09). The difference measured in minutes between the means of IPS Case Designer ® and Dolphin Imaging ® was 2.9, between ProPlan CMF ® and Dolphin Imaging ® 11.9, and between ProPlan CMF ® and IPS Case Designer ® 9.

The three tested VSP systems are available in different software packages. The costs are in a similar range. Dependent on which package to choose, asset costs for acquiring the software, license fee, license possibilities, paying for support services, and service contract costs differ. The authors decided to show these results in tables. For the VSP system IPS Case Designer ®, see Table 1.

Costs of the VSP system Dolphin Imaging ® are shown in Table 2.

In the Dolphin Business version, the license is perpetual. The annual fee is not mandatory, but updates or support run out if not paid.

In the VSP system ProPlan CMF ®—see Table 3—there is no initial software training included in the price. But it is possible to buy a training session.

Costs for splint production in cooperation with the current company were also assessed. The files could be exported for free and the splints can be built in a 3D printer. The VSP system IPS Case Designer ® from the KLS Martin Group company was the only application software which offers the possibility to send the splint files during the planning process via data transfer for production. The splints will be sent back per post. Costs for splint fabrication were 182.25 $ per splint.

As a strength, the authors mention that for evaluation of time consumption, all VSP was performed by one experienced person who had been trained on all three software applications. All work was done with the same PC.

A further strength is the chosen patient collective for this comparison. Nineteen already finished cases with available pre- and post-operative radiological 3D datasets were used for a realistic second planning of IQLFIIO, a complex surgical intervention. The surgical aim was the actually reached situation as found in the post-operative scans. We have successfully developed a standardized workflow for all three compared applications.

An aim of this study is to give an overview about the different costs and license products. These are different, but in similar ranges in all three software applications. It is difficult to perform and publish a price comparison because companies sometimes quickly change their price policies. This is a limitation of this study. However, the authors think that this work gives a suitable overview about the level of costs allowing to estimate usability in surgical planning routine.

For the system IPS Case Designer ®, the costs are outlined on the homepage of the company and apparent for everyone. For Dolphin Imaging ® and ProPlan CMF ®, the company has to be contacted to acquire cost information. One possible limitation of this study is that the authors only give a financial orientation instead of a price/performance ratio. However, it only seems to be possible to assess a price/performance ratio if the whole functional range is considered. This was not an objective of this work.

Generally, costs are higher; the more steps of the planning process have to be outsourced [6].