A learning curve in 3D virtual surgical planned orthognathic surgery

OBJECTIVES

To assess the surgical accuracy of 3D virtual surgical planned orthognathic surgery and the influence of posterior impaction and magnitude of the planned movements on a possible learning curve.

MATERIALS AND METHODS

This prospective cohort study included subjects who underwent bimaxillary surgery between 2016 and 2020 at the Department of Oral and Maxillofacial Surgery of the Radboud University Medical Center, Nijmegen. 3D virtual surgical planning (VSP) was performed with CBCT data and digitalized dentition data. By using voxel-based matching with pre- and postoperative CBCT data the maxillary movements were quantified in six degrees of freedom. The primary outcome variable, surgical accuracy, was defined as the difference between the planned and achieved maxillary movement.

RESULTS

Based on 124 subjects, the surgical accuracy increased annually from 2016 to 2020 in terms of vertical translations (0.82 ± 0.28 mm; p = 0.038) and yaw rotations (0.68 ± 0.22°; p = 0.028). An increase in surgical accuracy was observed when combining all six degrees of freedom (p = 0.021) and specifically between 2016 and 2020 (p = 0.004). An unfavorable learning curve was seen with posterior impaction and with a greater magnitude of movements.

CONCLUSION

The present study demonstrated a significant increase in surgical accuracy annually and therefore supports the presence of a learning curve.

CLINICAL RELEVANCE

Cases with planned maxillary posterior impaction and/or a great magnitude of jaw movements should be transferred from the 3D VSP with extra care to obtain a satisfactory surgical accuracy.

Computed tomography imaging superimposition protocols to assess outcomes in orthognathic surgery: a systematic review with comprehensive recommendations

OBJECTIVES

A systematic review was performed to analyze the current evidence on three-dimensional (3D) computed tomography (CT) superimposition protocols used to assess dentomaxillofacial changes after orthognathic and orthofacial surgery. Accuracy, reproducibility, and efficiency were evaluated.

METHODS

The search was divided into Main Search (PubMed, EMBASE, Cochrane Library, LILACS, and SciELO), Grey Literature search (Google Scholar and Open Grey), and Manual search. Thirteen studies were included. Of these, 10 reported data on accuracy, 10 on reproducibility and five on efficiency. Seven proposed or evaluated methods of voxel-based superimposition, three focused on the surface-based technique, one compared surface- and voxel-based superimposition protocols, one used the maximum mutual information algorithm, and one described a landmark-based superimposition method. Cone-beam computed tomography (CBCT) was the most common imaging technique, being used in 10 studies.

RESULTS

The accuracy of most methods was high, showing mean differences smaller than voxels' dimensions, ranging between 0.05 and 1.76 mm for translational accuracy, and 0.10-1.09° for rotational accuracy. The overall reproducibility was considered good as demonstrated by the small mean error (range: 0.01-0.26 mm) and high correlation coefficients (range: 0.53-1.00). Timing to complete virtual superimposition techniques ranged between a few seconds up to 40 min.

CONCLUSIONS

Voxel-based superimposition protocols presented the highest accuracy and reproducibility. Moreover, superimposition protocols that used automated processes and involved only one software were the most efficient.

Intraoral scanner featuring transillumination for proximal caries detection. An in vitro validation study on permanent posterior teeth

OBJECTIVES

To assess the validity of an intraoral scanner system featuring near-infrared (NIR) transillumination to aid the detection of proximal caries lesions, and to compare the diagnostic performance of this system with that of conventional caries detection methods and with that of an intraoral camera featuring NIR transillumination (DIAGNOcam).

METHODS

Ninety-five permanent posterior teeth were examined using a prototype tip functioning with TRIOS 4 intraoral scanner system (3Shape TRIOS A/S, Denmark) and emitting NIR light, DIAGNOcam, and visual and radiographic examination employing ICDAS criteria. One or two approximal surfaces per tooth, sound or with caries lesions at different stages, were examined (N₁=158). Histological assessment was used as the reference standard.

RESULTS

All methods showed excellent intra-examiner reliability (κ_intra ≥0.80). Two independent examiners assessed the NIR images obtained with both devices. The first examiner, who obtained and assessed the images, showed improved diagnostic performance than the second examiner, who only had access to the images. The inter-examiner agreement between the two examiners assessing the NIR images was substantial (κ_inter 0.57-0.72). The intraoral scanner and DIAGNOcam showed similar diagnostic performance. Regarding initial caries lesions, the NIR image assessment resulted in equal or improved sensitivity (SE 0.50-0.89) compared to radiographic assessment (SE 0.49-0.51) and higher than visual examination (SE 0.28-0.39). Radiographic and NIR image assessment resulted in similar SE in detecting moderate-extensive dentin caries lesions (SE 0.59-0.70), while visual examination showed an inferior value (SE 0.30).

CONCLUSIONS

The intraoral scanner system featuring NIR transillumination and DIAGNOcam showed an overall good diagnostic performance. The conventional caries detection methods showed inferior sensitivity at initial caries lesion stages.

CLINICAL SIGNIFICANCE

Considering the promising diagnostic performance of the intraoral scanner featuring transillumination and the advantages offered by combining the NIR images with the 3D models of the teeth, this system has the potential to contribute towards more reliable caries detection and monitoring in clinical practice without the use of ionizing radiation.

[Analysis of lumbosacral sagittal balance parameter variation in minimally invasive transforaminal lumbar interbody fusion with real-time 3D navigation techniques]

OBJECTIVE

To explore the dynamic changes of lumbosacral sagittal parameters after real-time three-dimensional navigation assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and traditional open TLIF for treatment of lumbar degenerative disease.

METHODS

The clinical data of 61 patients with lumbar degenerative disease underwent single-segment surgery from September 2017 to September 2019 were retrospectively analyzed. Among them, 31 cases underwent MIS-TLIF with 3D navigation techniques (MIS-TLIF group) and another 30 cases underwent conventional open TLIF (traditional open TLIF group). The basic information, operative time and intraoperative blood loss were collected. The sagittal radiologic parameters were measured before surgery and 3 months after surgery, including lumbar lordosis (LL), segmental lordosis (SL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), anterior disc height (ADH), posterior disc height(PDH).And the average disc height(DH) and pelvic incidence to lumbar lordosis mismatch (PI-LL) were calculated.

RESULTS

Operative time and intraoperative blood loss in MIS-TLIF group were significantly less than in traditional open TLIF group(P<0.05). In MIS-TLIF group, LL, SL, PI-LL, and DH were significantly improved at 3 months after surgery (P<0.05), while PI, PT, and SS were not statistically different from those before surgery (P>0.05). LL, PI-LL, and DH of patients in the traditional open TLIF group were significantly improved at 3 months after surgery (P<0.05), while the PI, PT, SS, and SL were not statistically different from those before surgery (P>0.05). LL change showed a significant correlation with SL change (r= 0.433, P<0.001). Change in SL closely correlated to change in ADH (r=0.621, P<0.05) and PDH(r=0.527, P<0.05).

CONCLUSION

Real-time navigation-assisted MIS-TLIF and traditional open TLIF can recover DH in a short term for lumbar degenerative diseases, improve LL and PI-LL, and make the arrangement of the sagittal plane of the lumbosacral region more coordinated after surgery. But only the navigation assisted MIS -TLIF can significantly improve SL. Compared with traditional open TLIF, real-time navigation assisted MIS-TLIF in the treatment of degenerative lumbar diseases has the advantages of short operation time and less intraoperative bleeding.

Morphological parameters of fourth lumbar spinous process palpation: a three-dimensional reconstruction of computed tomography

Background

The localization of lumbar fourth spinous process (L4-SP) is an important anatomical landmark, and identifying its accurate position is essential for the diagnosis and treatment of waist diseases.

Methods

Five hundred participants were scanned with positive and lateral computed tomography (CT), which aimed to clarify anatomic characteristics of L4-SP. Anatomical parameters of the surface localization of L4-SP were measured and recorded through a three-dimensional (3D) reconstruction.

Results

Five hundred participants were classified into three types according to the position of BC with the iliac spine. There are just 266 that the line between the highest point of the iliac spine on both sides located on L4-SP (type I, 53.20%), 16 above L4-SP (type II, 3.20%), and 218 below L4-SP (type III, 43.60%). BC in type I (15.92 ± 1.30 mm) is longer than type III (15.56 ± 1.32 mm). While the angle combined with AB and BC is different in the three groups, the angle in type I (173.00 ± 4.83°) is larger than that in type II (164.69 ± 5.50°) and type III (159.45 ± 8.39°). Other measurements were not found any significant differences between above.

Conclusion

The traditional palpation for L4-SP is not absolutely exact. The accuracy rate is only 53.20%, and the errors may cause serious consequences.

Performance of Cone Beam Computed Tomography Systems in Visualizing the Cortical Plate in 3D Image Reconstruction: An In Vitro Study

INTRODUCTION

Cortical bone is an important anatomical structure and its thickness needs to be determined prior to many dental procedures to ensure treatment success. Imaging modalities are necessarily used in dentistry for treatment planning and dental procedures. Three-dimensional image reconstruction not only provides visual information but also enables accurate measurement of anatomical structures; thus, it is necessarily required for maxillofacial examination and in case of skeletal problems in this region.

AIMS

This study aimed to assess the ability of three Cone Beam Computed Tomography (CBCT) systems including Cranex 3D, NewTom 3G and 3D Promax for Three-Dimensional (3D) image reconstruction of the cortical plate with variable thicknesses.

METHODS

Depending on the cortical bone thickness, samples were evaluated in three groups of ≤ 0. 5 mm, 0.6 -1 mm and 1.1-1.5 mm cortical bone thickness. The CBCT scans were obtained from each sample using three systems, their respective FOVs, and 3D scans were reconstructed using their software programs. Two observers viewed the images twice with a two-week interval. The ability of each system in the 3D reconstruction of different thicknesses of cortical bone was determined based on its visualization on the scans. The data were analyzed using SPSS and Kappa test.

RESULTS

The three systems showed the greatest difference in the 3D reconstruction of cortical bone with < 0.5 mm thickness. Cranex 3D with 4×6 cm2 FOV had the highest and 3D Promax with 8×8 cm2 FOV had the lowest efficacy for 3D reconstruction of cortical bone. Cranex 3D with 4×6 cm2 and 6×8 cm2 FOVs and NewTom 3G with 5×5 cm2 and 8×5 cm2 FOVs showed significantly higher efficacy for 3D reconstruction of cortical bone with 0.6-1mm thickness while 3D Promax followed by NewTom 3G with 8×8 cm2 FOV had the lowest efficacy for this purpose.

CONCLUSION

Most CBCT systems have high efficacy for 3D image reconstruction of cortical bone with thicknesses over 1 mm while they have poor efficacy for image reconstruction of cortical bone with less than 0.5 mm thickness. Thus, for accurate visualization of anatomical structures on CBCT scans, systems with smaller FOVs and consequently smaller voxel size are preferred.

Quantitative MDCT assessment of binder effects after pelvic ring disruptions using segmented pelvic haematoma volumes and multiplanar caliper measurements

OBJECTIVE

To assess effects of pelvic binders for different instability grades using quantitative multidetector computed tomography (MDCT) parameters including segmented pelvic haematoma volumes and multiplanar caliper measurements.

METHODS

CT examinations of 49 patients with binders and 49 controls performed from January 2008-June 2016, and matched 1:1 for Tile instability grade and Pennal/Young-Burgess force vector, were compared for differences in pubic symphysis and sacroiliac displacement using caliper measurements in three orthogonal planes. Pelvic haematoma volumes (ml) were derived using semi-automated seeded region-growing segmentation. Median caliper measurements and volumes were compared using the Mann-Whitney U test, and correlations assessed with Pearson's correlation coefficient. Relevant caliper measurement cutoffs were established using ROC analysis.

RESULTS

Rotationally unstable (Tile B) patients with binders showed significant decreases in sacroiliac diastasis (2.7 mm vs. 4.5 mm; p=0.003) and haematoma volumes (135 ml vs. 295 ml; p=0.008). Globally unstable (Tile C) binder patients showed decreased sacroiliac diastasis (4.7 mm vs. 6.4 mm, p=0.04), without significant difference in haematoma volumes (284 ml vs. 234 ml, p=0.34). Four Tile C patients with binders demonstrated over-reduction resulting in pubic body over-ride.

CONCLUSION

Rotationally unstable patients with binders have significantly less sacroiliac diastasis versus controls, corresponding with significantly lower haematoma volumes.

KEY POINTS

• Haematoma segmentation and multiplanar caliper measurements provide new insights into binder effects. • Binder reduction corresponds with decreased pelvic haematoma volume in rotationally unstable injuries. • Discrimination between rotational and global instability is important for management. • Several caliper measurement cut-offs discriminate between rotationally and globally unstable injuries. • Pubic symphysis over-ride is suggestive of binder over-reduction in globally unstable injuries.

Angioarchitecture of Spinal Dural Arteriovenous Fistula - Evaluation with 3D Rotational Angiography

Purpose

The complex angioarchitecture of spinal dural arteriovenous fistulas (SDAVFs) sometimes preclude angiographic analyses or superselective procedures. Therefore, the effectiveness of 3 dimensional rotational angiography (3DRA) as a detailed imaging technique for SDAVFs was evaluated.

Materials and Methods

Of 57 patients with spinal vascular malformations, recent 13 SDAVF patients underwent 3DRA. The advantage of 3DRA compared to digital subtraction angiography (DSA) in imaging SDAVF was assessed. Angioarchitecture of SDAVF was focused on location, number, and course of feeders and draining vein. Appropriate angled views were also selected to reveal the segmental artery and feeders.

Results

3DRA technique provided additional information for imaging evaluation of SDAVFs compared to DSA; the presence of multiple feeders, including their transdural portions, as well as their courses. The contralaterally angled anterior-oblique-caudal (spider) view showed the radicular feeder by separating the intercostal artery and the dorsal muscular branch. The bottom-to-up (tunnel) view was useful for revealing the location (ventral vs. dorsal) including sharp medial turn of the dural feeder. The dual mode, which displays both vessels and bones, revealed the course of the feeders and the fistula related to the spinal bony column.

Conclusion

Because spinal vasculature overlaps in DSA, 3DRA revealed additional information for evaluations of the number and transdural course of fistular feeders in SDAVFs, and it offers working angles to obtain appropriate views.