Three-dimensional semi-automated volumetric assessment of the pulp space of teeth following regenerative dental procedures

Abstract

The volumetric change that occurs in the pulp space over time represents a critical measure when it comes to determining the secondary outcomes of regenerative endodontic procedures (REPs). However, to date, only a few studies have investigated the accuracy of the available domain-specialized medical imaging tools with regard to three-dimensional (3D) volumetric assessment. This study sought to compare the accuracy of two different artificial intelligence-based medical imaging programs namely OsiriX MD (v 9.0, Pixmeo SARL, Bernex Switzerland, https://www.osirix-viewer.com ) and 3D Slicer ( http://www.slicer.org ), in terms of estimating the volume of the pulp space following a REP. An Invitro assessment was performed to check the reliability and sensitivity of the two medical imaging programs in use. For the subsequent clinical application, pre- and post-procedure cone beam computed tomography scans of 35 immature permanent teeth with necrotic pulp and periradicular pathosis that had been treated with a cell-homing concept-based REP were processed using the two biomedical DICOM software programs (OsiriX MD and 3D Slicer). The volumetric changes in the teeth's pulp spaces were assessed using semi-automated techniques in both programs. The data were statistically analyzed using t-tests and paired t-tests (P = 0.05). The pulp space volumes measured using both programs revealed a statistically significant decrease in the pulp space volume following the REP (P < 0.05), with no significant difference being found between the two programs (P > 0.05). The mean decreases in the pulp space volumes measured using OsiriX MD and 3D Slicer were 25.06% ± 19.45% and 26.10% ± 18.90%, respectively. The open-source software (3D Slicer) was found to be as accurate as the commercially available software with regard to the volumetric assessment of the post-REP pulp space. This study was the first to demonstrate the step-by-step application of 3D Slicer, a user-friendly and easily accessible open-source multiplatform software program for the segmentation and volume estimation of the pulp spaces of teeth treated with REPs.

Figure 1

In vitro Validation. Tooth root volume assessment by CBCT segmentation with (A) OsiriX MD and (B) 3D Slicer software’s. (C) Illustrates volumetric analyses of the tooth root in Materialise MiniMagics software after scanning with Steinbichler COMET L3D laser equipment. (D) Illustrates volume estimation of the tooth root by water displacement method.

Figure 2

Pulp space volume assessment using OsiriX MD (A) illustrates the ROI in various axial slices and (B) reconstructed 3D model along with the volume statistics.

Figure 3

Grow Cut technique in 3D Slicer (A) initialization of an area inside and outside the ROI using paint effect (blue arrow). (B) automatic competing region- growing using GrowCut effect (red arrow).

Figure 4

Pulp space volume assessment using 3D Slicer: illustrates the ROI in the axial, saggital and coronal slicing as well as the reconstructed 3D model with the calculated volume.

Figure 5

Voxel-based superimposition. Axial slice (A), sagittal slice (B) and 3d reconstruction (C) showing post pulp volume segmentation (green) superimposed over the pre pulp volume segmentation (brown).

Figure 6

Invitro validation. Bland–Altman Plot comparison between (A) CBCT segmented volumes from OsiriX MD and real volumes from Laser scans. (B) CBCT segmented volumes from OsiriX MD and real volumes from water displacement method (C) CBCT segmented volumes from 3D Slicer and real volumes from Laser scans. (D) CBCT segmented volumes from 3D Slicer and real volumes from water displacement method. The difference between the measurements is plotted against their mean.

Figure 7

Bar diagram depicting the decrease in volume (mean) calculated with OsiriX MD and 3D Slicer based on the initial (pre) and the final (post) CBCT scans.