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Nedelcu, R., Olsson, P., Thulin, M., Nyström, I. & Thor, A. (2023). In vivo trueness and precision of full-arch implant scans using intraoral scanners with three different acquisition protocols. Journal of Dentistry, 128, 104308-104308, Article ID 104308.
Open this publication in new window or tab >>In vivo trueness and precision of full-arch implant scans using intraoral scanners with three different acquisition protocols
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2023 (English)In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 128, p. 104308-104308, article id 104308Article in journal (Refereed) Published
Abstract [en]

Objectives: To evaluate an in situ reference acquisition method for implant positions in complete edentulous maxillae using an industrial scanner and allowing for in vivo trueness analysis of the restorative workflow. To assess in vivo trueness and precision of intraoral scanners (IOS) using different acquisition protocols. Furthermore, to compare IOS trueness with impression-based models and implant-supported fixed dentures (IFD) in a parallel study on the same cohort using the same in situ reference scan.

Methods: Six scan-bodies mounted to maxillary implants in five subjects were reference scanned (REF) using an industrial scanner. Subjects were scanned with IOS three times using three different protocols: control (CT), dental floss assisted (DF), and acrylic splint (SP). CAD-files of scan-bodies with inter-aligned analogues were geometry-aligned to REF, and SP. Scan-bodies were aligned to CT and DF in proprietary dental laboratory software and exported with analogue positions. Resulting six CAD-analogues per scan were Globally Aligned using a consistent geometry-based alignment. Deviations were computed after a Reference Point System Alignment at the implant/prosthetic platform for Cartesian axes with a linear Resultant.

Results: Resultant trueness was CT: 41±11 μm, DF: 49±22 μm, SP: 55±8 μm. Resultant precision was CT: 48±7μm, DF: 50±7 μm, SP: 45±6 μm

Conclusions: This method is applicable for assessing trueness of maxillary full-arch implant scans in vivo. The CTprotocol was most accurate. CT trueness showed no difference to digitised impression-based models in parallelstudy. CT was more accurate than IFD in a parallel study. CT displayed similar numerical trueness as existing invitro studies.

Critical significance: Using IOS to acquire full-arch implant scans is controversial. The modified protocol in thispilot shows promising results in the maxilla where great care was taken to manage non-attached tissues when amodified scanning pattern was used. However, other IOS may show varying results in vivo. A completed scan doesnot necessarily equate to an accurate scan.

Place, publisher, year, edition, pages
ElsevierElsevier BV, 2023
National Category
Dentistry
Identifiers
urn:nbn:se:uu:diva-490180 (URN)10.1016/j.jdent.2022.104308 (DOI)000992408700001 ()
Available from: 2022-12-07 Created: 2022-12-07 Last updated: 2024-01-15Bibliographically approved
Nedelcu, R., Olsson, P., Thulin, M., Nyström, I. & Thor, A. (2023). In vivo trueness of full-arch implant-supported CAD/CAM restorations and models based on conventional impressions. Journal of Dentistry, 128, 104381-104381, Article ID 104381.
Open this publication in new window or tab >>In vivo trueness of full-arch implant-supported CAD/CAM restorations and models based on conventional impressions
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2023 (English)In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 128, p. 104381-104381, article id 104381Article in journal (Refereed) Published
Abstract [en]

Objectives: To evaluate a method for in situ reference acquisition of implant positions in complete edentulous maxillae using an industrial scanner. To assess in vivo trueness of full-arch implant-supported fixed dentures (IFD) and dental models based on conventional impressions.

Methods: In five subjects, scan-bodies were mounted to six maxillary implants and scanned three times using an industrial scanner (REF). Original impression-based models used to manufacture existing IFDs, (MOD1), and models fabricated from new polyether impressions, (MOD2), were scanned three times with a laboratory scanner. Scan-bodies were aligned and exported with analogue positions corresponding to implant positions. Implant analogues were mounted onto existing IFDs and scanned three times (BRIDGE). CAD files of scan-bodies with inter-aligned CAD-analogues were geometry-aligned to REF. CAD-analogues were aligned to exported files of MOD1 and MOD2, and to BRIDGE. Resulting six CAD-analogues were Globally Aligned using a consistent geometry-based alignment. Deviations were computed after a Reference Point System Alignment at the implant/prosthetic platform for Cartesian axes and a linear Resultant.

Results:REF precision was 9.3 ± 1 µm. In vivo trueness for Resultant was MOD1: 36±16 µm, MOD2: 28±7 µm and BRIDGE: 70±23 µm, where MOD1 and MOD2 were statistically significantly different from BRIDGE. In vitro manufacturing trueness of Resultant when MOD1 acted reference for BRIDGE was: 69 ± 22.

Conclusions: This method can be applied for assessing in vivo trueness. CAD/CAM processed IFD showed deviations twice that of impression-based models, however, errors from impressions and subsequent model scans were not additive to the entire workflow.

Place, publisher, year, edition, pages
ElsevierElsevier BV, 2023
National Category
Dentistry
Identifiers
urn:nbn:se:uu:diva-490355 (URN)10.1016/j.jdent.2022.104381 (DOI)000992534000001 ()
Available from: 2022-12-09 Created: 2022-12-09 Last updated: 2024-01-15Bibliographically approved
Bengtsson Bernander, K., Lindblad, J., Strand, R. & Nyström, I. (2022). Rotation-Equivariant Semantic Instance Segmentation on Biomedical Images. In: Yang, G Aviles-Rivero, A Roberts, M Schonlieb, CB (Ed.), Medical Image Understanding and Analysis, MIUA 2022: . Paper presented at 26th Annual Conference on Medical Image Understanding and Analysis (MIUA), JUL 27-29, 2022, Univ Cambridge, Cambridge, ENGLAND (pp. 283-297). Springer, 13413
Open this publication in new window or tab >>Rotation-Equivariant Semantic Instance Segmentation on Biomedical Images
2022 (English)In: Medical Image Understanding and Analysis, MIUA 2022 / [ed] Yang, G Aviles-Rivero, A Roberts, M Schonlieb, CB, Springer, 2022, Vol. 13413, p. 283-297Conference paper, Published paper (Refereed)
Abstract [en]

Advances in image segmentation techniques, brought by convolutional neural network (CNN) architectures like U-Net, show promise for tasks such as automated cancer screening. Recently, these methods have been extended to detect different instances of the same class, which could be used to, for example, characterize individual cells in whole-slide images. Still, the amount of data needed and the number of parameters in the network are substantial. To alleviate these problems, we modify a method of semantic instance segmentation to also enforce equivariance to the p4 symmetry group of 90-degree rotations and translations. We perform four experiments on a synthetic dataset of scattered sticks and a subset of the Kaggle 2018 Data Science Bowl, the BBBC038 dataset, consisting of segmented nuclei images. Results indicate that the rotation-equivariant architecture yields similar accuracy as a baseline architecture. Furthermore, we observe that the rotation-equivariant architecture converges faster than the baseline. This is a promising step towards reducing the training time during development of methods based on deep learning.

Place, publisher, year, edition, pages
Springer, 2022
Series
Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349
Keywords
Deep learning, Training, Convergence
National Category
Medical Image Processing
Identifiers
urn:nbn:se:uu:diva-489580 (URN)10.1007/978-3-031-12053-4_22 (DOI)000883331000022 ()978-3-031-12053-4 (ISBN)978-3-031-12052-7 (ISBN)
Conference
26th Annual Conference on Medical Image Understanding and Analysis (MIUA), JUL 27-29, 2022, Univ Cambridge, Cambridge, ENGLAND
Funder
Wallenberg AI, Autonomous Systems and Software Program (WASP)
Available from: 2022-12-02 Created: 2022-12-02 Last updated: 2022-12-02Bibliographically approved
Nyström, I. & Ruiz-Shulcloper, J. (2021). Editorial of special section on CIARP 2019. Pattern Recognition Letters, 148, 82-83
Open this publication in new window or tab >>Editorial of special section on CIARP 2019
2021 (English)In: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 148, p. 82-83Article in journal, Editorial material (Other academic) Published
National Category
Computer Vision and Robotics (Autonomous Systems)
Identifiers
urn:nbn:se:uu:diva-453657 (URN)10.1016/j.patrec.2021.04.014 (DOI)000674680600013 ()
Available from: 2021-09-22 Created: 2021-09-22 Last updated: 2021-09-22Bibliographically approved
Nilsson, J., Nysjö, F., Nyström, I., Kämpe, J. & Thor, A. (2021). Evaluation of in-house, haptic assisted surgical planning for virtual reduction of complex mandibular fractures. International Journal of Computer Assisted Radiology and Surgery, 16(6), 1059-1068
Open this publication in new window or tab >>Evaluation of in-house, haptic assisted surgical planning for virtual reduction of complex mandibular fractures
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2021 (English)In: International Journal of Computer Assisted Radiology and Surgery, ISSN 1861-6410, E-ISSN 1861-6429, Vol. 16, no 6, p. 1059-1068Article in journal (Refereed) Published
Abstract [en]

The management of complex mandible fractures, i.e severely comminuted or fractures of edentulous/atrophic mandibles, can be challenging. This is due to the three-dimensional loss of bone, which limits the possibility for accurate anatomic reduction. Virtual surgery planning (VSP) can provide improved accuracy and shorter operating times, but is often not employed for trauma cases because of time constraints and complex user interfaces limited to two-dimensional interaction with three-dimensional data. In this study, we evaluate the accuracy, precision, and time efficiency of the Haptic Assisted Surgery Planning system (HASP), an in-house VSP system that supports stereo graphics, six degrees-of-freedom input and haptics, to improve the surgical planning. Three operators performed planning in HASP on Computed Tomography (CT) and Come Beam Computed Tomography (CBCT) images of a plastic skull model and on twelve retrospective cases with complex mandible fractures. The result shows an accuracy and reproducibility of less than 2mm when using HASP, with an average planning time of 15 minutes, including time for segmentation in the software BoneSplit. This study presents an in-house haptic assisted planning tool for cranio-maxillofacial surgery with high usability that can be used for preoperative planning and evaluation of complex mandible fractures. 

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Virtual surgical planning, Haptic technology, Complex mandible fractures.
National Category
Medical Image Processing Surgery
Research subject
Surgery; Computerized Image Processing
Identifiers
urn:nbn:se:uu:diva-377518 (URN)10.1007/s11548-021-02353-w (DOI)000644782600001 ()33905085 (PubMedID)
Available from: 2019-02-25 Created: 2019-02-25 Last updated: 2024-01-15Bibliographically approved
Bengtsson Bernander, K., Lindblad, J., Strand, R. & Nyström, I. (2021). Replacing data augmentation with rotation-equivariant CNNs in image-based classification of oral cancer. In: : . Paper presented at 25th Iberoamerican Congress on Pattern Recognition, Porto, Portugal, 10 - 13 May 2021.
Open this publication in new window or tab >>Replacing data augmentation with rotation-equivariant CNNs in image-based classification of oral cancer
2021 (English)Conference paper, Published paper (Refereed)
National Category
Medical Image Processing
Identifiers
urn:nbn:se:uu:diva-460520 (URN)
Conference
25th Iberoamerican Congress on Pattern Recognition, Porto, Portugal, 10 - 13 May 2021
Funder
Wallenberg AI, Autonomous Systems and Software Program (WASP)
Available from: 2021-12-07 Created: 2021-12-07 Last updated: 2024-01-09Bibliographically approved
Nysjö, F., Malmberg, F. & Nyström, I. (2020). RayCaching: Amortized Isosurface Rendering for Virtual Reality. Computer graphics forum (Print), 39(1), 220-230
Open this publication in new window or tab >>RayCaching: Amortized Isosurface Rendering for Virtual Reality
2020 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 39, no 1, p. 220-230Article in journal (Refereed) Published
Abstract [en]

Real‐time virtual reality requires efficient rendering methods to deal with high‐ resolution stereoscopic displays and low latency head‐tracking. Our proposed RayCaching method renders isosurfaces of large volume datasets by amortizing raycasting over several frames and caching primary rays as small bricks that can be efficiently rasterized. An occupancy map in form of a clipmap provides level of detail and ensures that only bricks corresponding to visible points on the isosurface are being cached and rendered. Hard shadows and ambient occlusion from secondary rays are also accumulated and stored in the cache. Our method supports real‐time isosurface rendering with dynamic isovalue and allows stereoscopic visualization and exploration of large volume datasets at framerates suitable for virtual reality applications.

Keywords
ray tracing, visibility, point-based models, virtual reality
National Category
Computer Sciences
Research subject
Computerized Image Processing
Identifiers
urn:nbn:se:uu:diva-398397 (URN)10.1111/cgf.13762 (DOI)000519969500017 ()
Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2020-05-06Bibliographically approved
Way, B. L. M., Khonsari, R. H., Karunakaran, T., Nysjö, J., Nyström, I., Dunaway, D. J., . . . Britto, J. A. (2019). Correcting exorbitism by monobloc frontofacial advancement in Crouzon–Pfeiffer syndrome: An age-specific, time-related, controlled study. Paper presented at EURAPS 2014, May 29–31, Lacco Ameno, Italy. Plastic and reconstructive surgery (1963), 143(1), 121e-132e
Open this publication in new window or tab >>Correcting exorbitism by monobloc frontofacial advancement in Crouzon–Pfeiffer syndrome: An age-specific, time-related, controlled study
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2019 (English)In: Plastic and reconstructive surgery (1963), ISSN 0032-1052, E-ISSN 1529-4242, Vol. 143, no 1, p. 121e-132eArticle in journal (Refereed) Published
National Category
Medical Image Processing
Research subject
Computerized Image Processing
Identifiers
urn:nbn:se:uu:diva-375236 (URN)10.1097/PRS.0000000000005105 (DOI)000455067400012 ()30589795 (PubMedID)
Conference
EURAPS 2014, May 29–31, Lacco Ameno, Italy
Available from: 2019-01-01 Created: 2019-01-29 Last updated: 2019-02-21Bibliographically approved
Nyström, I., Heredia, Y. H. & Núñez, V. M. (Eds.). (2019). Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications. Paper presented at 24th Iberoamerican Congress on Pattern Recognition (CIARP 2019), 28-31 October, 2019, Havana, Cuba. Springer-Verlag New York
Open this publication in new window or tab >>Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications
2019 (English)Conference proceedings (editor) (Refereed)
Place, publisher, year, edition, pages
Springer-Verlag New York, 2019. p. 793
Series
Lecture Notes in Computer Science book series (LNCS, volume 11896), ISSN 0302-9743 ; 11896
National Category
Discrete Mathematics
Research subject
Computerized Image Processing
Identifiers
urn:nbn:se:uu:diva-408047 (URN)978-3-030-33903-6 (ISBN)
Conference
24th Iberoamerican Congress on Pattern Recognition (CIARP 2019), 28-31 October, 2019, Havana, Cuba
Available from: 2020-04-02 Created: 2020-04-02 Last updated: 2020-09-10Bibliographically approved
Nedelcu, R., Olsson, P., Nyström, I., Rydén, J. & Thor, A. (2018). Accuracy and precision of 3 intraoral scanners and accuracy of conventional impressions: A novel in vivo analysis method. Journal of Dentistry, 69, 110-118
Open this publication in new window or tab >>Accuracy and precision of 3 intraoral scanners and accuracy of conventional impressions: A novel in vivo analysis method
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2018 (English)In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 69, p. 110-118Article in journal (Refereed) Published
Abstract [en]

Objective: To evaluate a novel methodology using industrial scanners as a reference, and assess in vivo accuracy of 3 intraoral scanners (IOS) and conventional impressions. Further, to evaluate IOS precision in vivo.

Methods: Four reference-bodies were bonded to the buccal surfaces of upper premolars and incisors in five subjects. After three reference-scans, ATOS Core 80 (ATOS), subjects were scanned three times with three IOS systems: 3M True Definition (3M), CEREC Omnicam (OMNI) and Trios 3 (TRIOS). One conventional impression (IMPR) was taken, 3M Impregum Penta Soft, and poured models were digitized with laboratory scanner 3shape D1000 (D1000). Best-fit alignment of reference-bodies and 3D Compare Analysis was performed. Precision of ATOS and D1000 was assessed for quantitative evaluation and comparison. Accuracy of IOS and IMPR were analyzed using ATOS as reference. Precision of IOS was evaluated through intra-system comparison.

Results: Precision of ATOS reference scanner (mean 0.6 mu m) and D1000 (mean 0.5 mu m) was high. Pairwise multiple comparisons of reference-bodies located in different tooth positions displayed a statistically significant difference of accuracy between two scanner-groups: 3M and TRIOS, over OMNI (p value range 0.0001 to 0.0006). IMPR did not show any statistically significant difference to IOS. However, deviations of IOS and IMPR were within a similar magnitude. No statistical difference was found for IOS precision.

Conclusion: The methodology can be used for assessing accuracy of IOS and IMPR in vivo in up to five units bilaterally from midline. 3M and TRIOS had a higher accuracy than OMNI. IMPR overlapped both groups. Clinical significance: Intraoral scanners can be used as a replacement for conventional impressions when restoring up to ten units without extended edentulous spans.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Digital impression, Intraoral scanner, Polyether impression, Accuracy, Precision, In vivo
National Category
Dentistry
Identifiers
urn:nbn:se:uu:diva-349829 (URN)10.1016/j.jdent.2017.12.006 (DOI)000425888000014 ()29246490 (PubMedID)
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2023-11-01Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9739-0364

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