| 1. |
- Dérand, Per, et al.
(author)
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Glomangioma: a case presentation.
- 2010
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In: Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. - : Elsevier BV. - 1531-5053 .- 0278-2391. ; 68:1, s. 204-7
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Research review (peer-reviewed)
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| 2. |
- Dérand, Per, et al.
(author)
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Imaging, virtual planning, design and production of patient specific implants and clinical validation in cranio-maxillo-facial surgery
- 2012
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In: Cranial maxillofacial Trauma and Reconstruction. - : SAGE Publications. - 1943-3875 .- 1943-3883. ; 5:3, s. 137-144
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Journal article (peer-reviewed)abstract
- The purpose of this article was to describe the workflow from imaging, via virtual design, to manufacturing of patient-specific titanium reconstruction plates, cutting guide and mesh, and its utility in connection with surgical treatment of acquired bone defects in the mandible using additive manufacturing by electron beam melting (EBM). Based on computed tomography scans, polygon skulls were created. Following that virtual treatment plans entailing free microvascular transfer of fibula flaps using patient-specific reconstruction plates, mesh, and cutting guides were designed. The design was based on the specification of a Compact UniLOCK 2.4 Large (Synthes®, Switzerland). The obtained polygon plates were bent virtually round the reconstructed mandibles. Next, the resections of the mandibles were planned virtually. A cutting guide was outlined to facilitate resection, as well as plates and titanium mesh for insertion of bone or bone substitutes. Polygon plates and meshes were converted to stereolithography format and used in the software Magics for preparation of input files for the successive step, additive manufacturing. EBM was used to manufacture the customized implants in a biocompatible titanium grade, Ti6Al4V ELI. The implants and the cutting guide were cleaned and sterilized, then transferred to the operating theater, and applied during surgery. Commercially available software programs are sufficient in order to virtually plan for production of patient-specific implants. Furthermore, EBM-produced implants are fully usable under clinical conditions in reconstruction of acquired defects in the mandible. A good compliance between the treatment plan and the fit was demonstrated during operation. Within the constraints of this article, the authors describe a workflow for production of patient-specific implants, using EBM manufacturing. Titanium cutting guides, reconstruction plates for fixation of microvascular transfer of osteomyocutaneous bone grafts, and mesh to replace resected bone that can function as a carrier for bone or bone substitutes were designed and tested during reconstructive maxillofacial surgery. A clinically fit, well within the requirements for what is needed and obtained using traditional free hand bending of commercially available devices, or even higher precision, was demonstrated in ablative surgery in four patients.
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| 3. |
- Dérand, Per, et al.
(author)
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Virtual bending of mandibular reconstruction plates using a computer-aided design
- 2009
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In: Journal of oral and maxillofacial surgery (Print). - : Elsevier BV. - 0278-2391 .- 1531-5053. ; 67:8, s. 1640-1643
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Journal article (peer-reviewed)abstract
- PURPOSE: The purpose of this study was to investigate the possibility of virtually designing and manufacturing a template for reconstruction plate bending, to be used during treatment of congenital or acquired bony entities. The outcome was compared with plates bent by the freehand approach in a stereolithographic skull model. MATERIALS AND METHODS: From a computed tomography examination, a polygon skull was created and the corresponding stereolithographic model retrieved. A polygon mesh of a Compact UniLock 2.4-mm plate was obtained from Synthes (Bettlach, Switzerland). The polygon plate was bent virtually around the mandible and rendered in all 3 dimensions, and a template was created. Five 10-hole plates were bent using this template, and five 10-hole plates were bent using a stereolithographic model as the template. The 2 groups were compared using the Wilcoxon signed rank test. P values less than .001 was considered to be statistically significant. RESULTS: No statistical difference was seen between the 2 methods. The median discrepancy between the 2 groups was 0.1 mm. CONCLUSION: Within the constraints of this investigation, by use of a virtually produced template based on a virtually planned reconstruction, it is possible to bend a reconstruction plate with the same degree of accuracy as that of the traditional freehand approach.
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| 4. |
- Haag, Per, et al.
(author)
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Firing temperature accuracy of four dental furnaces
- 2011
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In: Swedish Dental Journal. - : Swedish Dental Association. - 0347-9994. ; 35:1, s. 25-31
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Journal article (peer-reviewed)abstract
- In spite of using recommended firing and displayed temperatures, low-fired dental porcelain more often demonstrates unsatisfactory results after firing than porcelain fired at higher temperatures. It could therefore be anticipated that temperatures shown on the display are incorrect, implying that the furnace does not render correct firing programs for low-fired porcelain. The purpose of this study is to investigate deviations from the real temperature during the firing process and also to illustrate the service and maintenance discipline of furnaces at dental laboratories. Totally 20 units of four different types of dental furnaces were selected for testing of temperature accuracy with usage of a digital temperature measurement apparatus, Therma 1. In addition,the staffs at 68 dental laboratories in Sweden were contacted for a telephone interview on furnace brand and on service and maintenance program performed at their laboratories. None of the 20 different dental furnaces in the study could generate the firing temperatures shown on the display, indicating that the hypothesis was correct. Multimat MCII had the least deviation of temperature compared with displayfigures. 62 out of 68 invited dental laboratories chose to participate in the interviews and the result was that very few laboratories had a service and maintenance program living up to quality standards. There is room for improving the precision of dental porcelain furnaces as there are deviations between displayed and read temperatures during the different steps of the firing process.
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| 5. |
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| 6. |
- Huo, Jinxing, et al.
(author)
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Failure location predictoin by finite element analysis for an additive manufactured mandible implant
- 2015
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In: Medical Engineering and Physics. - : Elsevier BV. - 1350-4533 .- 1873-4030. ; 37:9, s. 862-869
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Journal article (peer-reviewed)abstract
- In order to reconstruct a patient with a bone defect in the mandible, a porous scaffold attached to a plate, both in a titanium alloy, was designed and manufactured using additive manufacturing. Regrettably, the implant fractured in vivo several months after surgery. The aim of this study was to investigate the failure of the implant and show a way of predicting the mechanical properties of the implant before surgery. All computed tomography data of the patient were preprocessed to remove metallic artefacts with metal deletion technique before mandible geometry reconstruction. The three-dimensional geometry of the patient's mandible was also reconstructed, and the implant was fixed to the bone model with screws in Mimics medical imaging software. A finite element model was established from the assembly of the mandible and the implant to study stresses developed during mastication. The stress distribution in the load-bearing plate was computed, and the location of main stress concentration in the plate was determined. Comparison between the fracture region and the location of the stress concentration shows that finite element analysis could serve as a tool for optimizing the design of mandible implants.
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| 7. |
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| 8. |
- Huo, Jinxing, et al.
(author)
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Finite Element Investigation of the In - Vivo Failure of a Titanium Alloy HumanJaw Implant
- 2014
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Conference paper (peer-reviewed)abstract
- In order to reconstruct a patient with a bone defect in the right lower jaw, a scaffold attached to a reconstruction plate, both in a titanium alloy, was designed and manufactured using three-dimensional printing technique. Regrettably the implant fractured in situ several months after surgery. This paper is orientated to investigate the reason for the implant’s failure and provide a way of predicting the mechanical properties of the implant before surgery. Preoperative, postoperative and implant-break computed tomography data of the patient were provided by the responsible surgeon. Metallic artifacts introduced by previous dental implants were removed with metallic deletion technique software beforehand. Three-dimensional volume of the patient’s jaw was thereafter reconstructed with trabecular bone removed based on the cleaned computed tomography data. The implant, screws and jaw were assembled together and meshed with triangular elements in Mimics 16.0. The assembly was imported into in-house software with surface mesh converted to linear tetrahedral mesh. Simulations were implemented under simplified but suitable loading conditions with the assumption that jaw was a linear elastic and homogeneous material. The stress distribution on the implant plate was calculated and the location of stress concentration on the plate was determined and then verified by the clinical data of the patient. This validated model could serve in the future as a tool for optimizing the design of jaw implants.
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| 9. |
- Jesson, Gerald, et al.
(author)
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Carbon Dioxide-Mediated Generation of Hybrid Nanoparticles for Improved Bioavailability of Protein Kinase Inhibitors
- 2014
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In: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 31:3, s. 694-705
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Journal article (peer-reviewed)abstract
- A versatile methodology is demonstrated for improving dissolution kinetics, gastrointestinal (GI) absorption, and bioavailability of protein kinase inhibitors (PKIs). The approach is based on nanoparticle precipitation by sub- or supercritical CO2 together with a matrix-forming polymer, incorporating surfactants either during or after nanoparticle formation. Notably, striking synergistic effects between hybrid PKI/polymer nanoparticles and surfactant added after particle formation is investigated. The hybrid nanoparticles, consisting of amorphous PKI embedded in a polymer matrix (also after 12 months), display dramatically increased release rate of nilotinib in both simulated gastric fluid and simulated intestinal fluid, particularly when surfactants are present on the hybrid nanoparticle surface. Similar results indicated flexibility of the approach regarding polymer identity, drug load, and choice of surfactant. The translation of the increased dissolution rate found in vitro into improved GI absorption and bioavalilability in vivo was demonstrated for male beagle dogs, where a 730% increase in the AUC(0-24h) was observed compared to the benchmark formulation. Finally, the generality of the formulation approach taken was demonstrated for a range of PKIs. Hybrid nanoparticles combined with surfactant represent a promising approach for improving PKI dissolution rate, providing increased GI absorption and bioavailability following oral administration.
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| 10. |
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| 11. |
- Vult von Steyern, Per, et al.
(author)
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Fracture strength of In-Ceram all-ceramic bridges in relation to cervical shape and try-in procedure. An in-vitro study.
- 2000
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In: European Journal of Prosthodontics and Restorative Dentistry. - 0965-7452. ; 8:4, s. 153-158
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Journal article (peer-reviewed)abstract
- Investigations were performed on the strength of dental porcelain depending on whether it was exposed to saliva before or after the final firing. Forty porcelain specimens were fabricated and subjected to different treatments. A three-point flexural test was performed. In a second study investigations were performed to compare how the cervical shape of the preparation influenced the fracture strength of fixed partial dentures made of glass-infiltrated aluminium oxide. It was concluded that short-term exposure to saliva could have a negative effect on the strength of porcelain and that all-ceramic bridges luted with non-adhesive luting techniques should be supported by abutments with shoulder preparations.
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