| 1. |
- Achilles, Silvio, et al.
(författare)
-
GPU-Accelerated Coupled Ptychographic Tomography
- 2022
-
Ingår i: Developments in X-Ray Tomography XIV. - : SPIE. - 0277-786X .- 1996-756X. - 9781510654686 ; 12242
-
Konferensbidrag (refereegranskat)abstract
- Scanning coherent X-ray microscopy (ptychography) has gained considerable interest during the last decade since the performance of this indirect imaging technique does not necessarily rely on the quality of the X-ray optics and, in principle, can achieve highest spatial resolution in X-ray imaging. The method can be easily extended to 3D by adding standard tomographic reconstruction schemes. However, the tomographic reconstruction is often applied in a subsequent step using a sequence of aligned ptychographic 2D projections. In this contribution, we outline current developments of a GPU-accelerated framework for direct 3D ptychography, coupling 2D ptychography and tomography. The program utilizes a custom GPU-accelerated framework for ptychography that offers three distinct ptychographic reconstruction algorithms. The tomographic reconstruction runs simultaneously and uses numerical routines of the ASTRA Toolbox. This parallel-computing approach results in a high performance increase considerably reducing the reconstruction time of 3D ptychographic datasets.
|
|
| 2. |
- Correa, Leticia, et al.
(författare)
-
Planning of dental implant size with digital panoramic radiographs, CBCT-generated panoramic images, and CBCT cross-sectional images
- 2014
-
Ingår i: Clinical Oral Implants Research. - : Blackwell Munksgaard. - 0905-7161 .- 1600-0501. ; 25:6, s. 690-695
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare the implant size (width and length) planned with digital panoramic radiographs, cone beam computed tomography (CBCT)-generated panoramic views, or CBCT cross-sectional images, in four implant systems. MATERIAL AND METHODS: Seventy-one patients with a total of 103 implant sites in the upper premolar and/or lower molar regions were examined with digital panoramic radiography (D-PAN) and (CBCT). A metal ball 5 mm in diameter was placed in the edentulous area for the D-PAN. CBCT data sets were reformatted to a 10-mm thick CBCT panoramic view (CBCT-pan) and 1-mm cross-sections (CBCT-cross). Measurements were performed in the images using dedicated software. All images were displayed on a monitor and assessed by three observers who outlined a dental implant by placing four reference points in the site of the implant-to-be. Differences in width and length of the implant-to-be from the three modalities were analyzed. The implant size selected in the CBCT-cross images was then compared to that selected in the other two modalities (D-PAN and CBCT-pan) for each of the implant systems separately. RESULTS: The implant-to-be (average measurements among observers) was narrower when measured in CBCT-cross compared with both D-PAN and CBCT-Pan. For premolar sites, the width also differed significantly between D-PAN and CBCT-pan modalities. The implant-to-be was also significantly shorter when recorded in CBCT-cross than in D-PAN. In premolar sites, there were no significant differences in implant length among the three image modalities. It mattered very little for the change in implant step sizes whether CBCT-cross was compared to D-PAN or CBCT-pan images. CONCLUSION: Our results show that the selected implant size differs when planned on panoramic or cross-section CBCT images. In most cases, implant size measured in cross-section images was narrower and shorter than implant size measured in a panoramic image or CBCT-based panoramic view
|
|
| 3. |
- Domic, Danijel, et al.
(författare)
-
Accuracy of cone beam computed tomography is limited at implant sites with a thin buccal bone : A laboratory study
- 2021
-
Ingår i: Journal of Periodontology. - : John Wiley & Sons. - 0022-3492 .- 1943-3670. ; 92:4, s. 592-601
-
Tidskriftsartikel (refereegranskat)abstract
- Background: To evaluate whether buccal bone thickness (BBT), implant diameter, and abutment/crown material influence the accuracy of cone beam computed tomography (CBCT) to determine the buccal bone level at titanium implants.Methods: Two implant beds (i.e., narrow and standard diameter) were prepared in each of 36 porcine bone blocks. The implant beds were positioned at a variable distance from the buccal bone surface, thus resulting in 3 BBT groups (i.e., > 0.5-1.0; > 1.0-1.5; > 1.5-2.0 mm). In half of the blocks, a buccal bone dehiscence of random extent ("depth") was created and implants were mounted with different abutment/crown material (i.e., titanium abutments with a metal-ceramic crown and zirconia abutments with an all-ceramic zirconia crown). The distance from the implant shoulder to the buccal bone crest was measured on cross-sectional CBCT images and compared to the direct measurements at the bone blocks.Results: While abutment/crown material and implant diameter had no effect on the detection accuracy of the buccal bone level at dental implants in CBCT scans, BBT had a significant effect. Specifically, when BBT was ≤ 1.0 mm, a dehiscence was often diagnosed although not present, i.e., the sensitivity was high (95.8%), but the specificity (12.5%) and the detection accuracy (54.2%) were low. Further, the average measurement error of the distance from the implant shoulder to the buccal bone crest was 1.6 mm.Conclusions: Based on the present laboratory study, BBT has a major impact on the correct diagnosis of the buccal bone level at dental titanium implants in CBCT images; in cases where the buccal bone is ≤ 1 mm thick, detection of the buccal bone level is largely inaccurate. This article is protected by copyright. All rights reserved.
|
|
| 4. |
- Liedke, Gabriela Salatino, et al.
(författare)
-
Accuracy of detecting and measuring buccal bone thickness adjacent to titanium dental implants-a cone beam computed tomography in vitro study
- 2018
-
Ingår i: Oral surgery, oral medicine, oral pathology and oral radiology. - : Elsevier. - 2212-4403 .- 2212-4411. ; 126:5, s. 432-438
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The aim of this study was to assess the accuracy of detecting and measuring buccal bone thickness (BBT) adjacent to titanium implants in cone beam computed tomography (CBCT) images. STUDY DESIGN: Titanium implants (1, 2, or 3), abutments, and metal-ceramic crowns were inserted into 40 bone blocks with various BBTs. CBCT images were acquired in various settings: Voxel sizes (0.2 and 0.13 mm) and reconstruction section thicknesses (2.0 and 5.0 mm) were assessed by 3 examiners. True BBT was measured in digital photographs of the bone blocks. Buccal bone detection was evaluated by sensitivity and specificity. BBT was evaluated by 1-way analysis of variance (ANOVA) between the true and the CBCT measurements and by calculating the difference between the true measurement and the CBCT measurement (Di-BBT). RESULTS: Detection of buccal bone exhibited high sensitivity (0.86-1) and low specificity (0.14-1). More implants in the field of view, large voxel size, and thick image reconstruction sections had a negative impact on buccal bone detection. ANOVA showed statistically significantly larger BBT for the CBCT measurements in all settings (1.07-1.21 mm) compared with the true measurements (0.85 mm). Di-BBT was mostly within 0.5 mm. CONCLUSIONS: BBT adjacent to titanium implants is overestimated when evaluated on CBCT cross-sectional images.
|
|
| 5. |
- Liedke, Gabriela S., et al.
(författare)
-
Factors affecting the possibility to detect buccal bone condition around dental implants using cone beam computed tomography
- 2017
-
Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 28:9, s. 1082-1088
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate factors with impact on the conspicuity (possibility to detect) of the buccal bone condition around dental implants in cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS: Titanium (Ti) or zirconia (Zr) implants and abutments were inserted into 40 bone blocks in a way to obtain variable buccal bone thicknesses. Three combinations regarding the implant-abutment metal (TiTi, TiZr, or ZrZr) and the number of implants (one, two, or three) were assessed. Two CBCT units (Scanora 3D - Sc and Cranex 3D - Cr) and two voxel resolutions (0.2 and 0.13 mm) were used. Reconstructed sagittal images (2.0 and 5.0 mm thickness) were evaluated by three examiners, using a dichotomous scale when assessing the condition of the buccal bone around the implants. A multivariate logistic regression was performed using examiners' detection of the buccal bone condition as the dependent variable. Odds ratio (OR) were calculated separately for each CBCT unit. RESULTS: Implant-abutment combination (ZrZr) (OR Sc = 19.18, OR Cr = 11.89) and number of implants (3) (OR Sc = 12.10, OR Cr = 4.25) had major impact on buccal bone conspicuity. The thinner the buccal bone, the higher the risk that the condition of the buccal bone could not be detected. The use of lower resolution protocols increased the risk that buccal bone was not properly detected (OR Sc = 1.46, OR Cr = 2.00). For both CBCT units, increasing the image reconstruction thickness increased the conspicuity of buccal bone (OR Sc = 0.33, OR Cr = 0.31). CONCLUSIONS: Buccal bone conspicuity was impaired by a number of factors, the implant-abutment material being the most relevant. Acquisition and reconstruction factors had minor impact on the detection of the buccal bone condition.
|
|
| 6. |
- Nilsson, Daniel, et al.
(författare)
-
Ronchi test for characterization of nanofocusing optics at a hard x-ray free-electron laser
- 2012
-
Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 37:24, s. 5046-5048
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of the classical Ronchi test to characterize aberrations in focusing optics at a hard x-ray free-electron laser. A grating is placed close to the focus and the interference between the different orders after the grating is observed in the far field. Any aberrations in the beam or the optics will distort the interference fringes. The methodis simple to implement and can provide single-shot information about the focusing quality. We used the Ronchi test to measure the aberrations in a nanofocusing Fresnel zone plate at the Linac Coherent Light Source at 8.194 keV.
|
|
| 7. |
- Schroer, Christian G, et al.
(författare)
-
Hard x-ray nanofocusing with refractive x-ray optics : full beam characterization by ptychographic imaging
- 2013
-
Ingår i: Proceedings of SPIE. - : SPIE. - 9780819496980 ; , s. 884807-
-
Konferensbidrag (refereegranskat)abstract
- Hard x-ray scanning microscopy relies on small and intensive nanobeams. Refractive x-ray lenses are well suited to generate hard x-ray beams with lateral dimensions of 100 nm and below. The diffraction limited beam size of refractive x-ray lenses mainly depends on the focal length and the attenuation inside the lens material. The numerical aperture of refractive lenses scales with the inverse square root of the focal length until it reaches the critical angle of total reflection. We have used nanofocusing refractive x-ray lenses made of silicon to focus hard x-rays at 8 and 20 keV to (sub-)100 nm dimensions. Using ptychographic scanning coherent diffraction imaging we have characterized these nanobeams with high accuracy and sensitivity, measuring the full complex wave field in the focus. This gives access to the full caustic and aberrations of the x-ray optics.
|
|
| 8. |
- Schropp, Andreas, et al.
(författare)
-
Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging
- 2013
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. 1633-
-
Tidskriftsartikel (refereegranskat)abstract
- The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125 nmusing refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics.
|
|
| 9. |
- Schropp, Andreas, et al.
(författare)
-
PtyNAMi : Ptychographic nano-analytical microscope
- 2020
-
Ingår i: Journal of Applied Crystallography. - 0021-8898. ; 53, s. 957-971
-
Tidskriftsartikel (refereegranskat)abstract
- Ptychographic X-ray imaging at the highest spatial resolution requires an optimal experimental environment, providing a high coherent flux, excellent mechanical stability and a low background in the measured data. This requires, for example, a stable performance of all optical components along the entire beam path, high temperature stability, a robust sample and optics tracking system, and a scatter-free environment. This contribution summarizes the efforts along these lines to transform the nanoprobe station on beamline P06 (PETRAIII) into the ptychographic nano-analytical microscope (PtyNAMi).
|
|
| 10. |
- Schropp, Andreas, et al.
(författare)
-
Scanning coherent x-ray microscopy as a tool for XFEL nanobeam characterization
- 2013
-
Ingår i: Proceedings of SPIE. - : SPIE. - 9780819496997
-
Konferensbidrag (refereegranskat)abstract
- During the last years, scanning coherent x-ray microscopy, also called ptychography, has revolutionized nanobeam characterization at third generation x-ray sources. The method yields the complete information on the complex valued, nanofocused wave field with high spatial resolution. In an experiment carried out at the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS) we successfully applied the method to an attenuated nanofocused XFEL beam with a size of 180(h) × 150(v) nm2 (FWHM) in horizontal (h) and vertical direction (v), respectively. It was created by a set of 20 beryllium compound refractive lenses (Be-CRLs). By using a fast detector (CSPAD) to record the diffraction patterns and a fast implementation of the phase retrieval code running on a graphics processing unit (GPU), the applicability of the method as a real-time XFEL nanobeam diagnostic is highlighted.
|
|
| 11. |
- Schropp, Lars, et al.
(författare)
-
Early, delayed, or late single implant placement : 10-year results from a randomized controlled clinical trial
- 2014
-
Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 25:12, s. 1359-1365
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to present the 10-year clinical and radiographic data from a RCT on single-tooth implants placed early, delayed, or late after tooth extraction. Materials and Methods: Sixty-three patients were randomly allocated to three groups and received an implant on average 10 days (Ea), 3 months (De), or 17 months (La) after tooth extraction. Second-stage surgery was performed after 3 months of submerged healing; metal-ceramic crowns were cemented after one additional month. Standardized periapical radiographs were taken 1 week after implant placement (TP), 1 week (TC) and 1–1.5 year (T1) after crown delivery, and 10 years after implant placement (T10). Pocket depth (PD) and bleeding on probing were registered during controls (TC – T10). Results: Two Ea and one De implants failed to osseointegrate. Seven patients (4 Ea, 1 De, and 2 La) were not available at T10. No significant differences were found among groups regarding implant survival or radiographic peri-implant marginal bone levels (Ea: 1.15 0.77; De: 1.53 1.06; La: 1.42 1.07) at T10. Similarly, no differences were observed among groups in the number of implants with PD ≥5 mm (Ea: 29%; De: 35%; La: 44%) or the average depth of the sites with PD ≥5 mm (Ea: 5.4 0.7; De: 6.1 1.4; La: 5.4 0.5) at T10. Peri-implant mucositis was found in 70% of the cases; peri-implantitis was diagnosed only in two implants (1 De, 1 La) corresponding to 4.3%. Conclusion: Single-tooth implants placed early or delayed after tooth extraction show high survival rates and limited peri-implant marginal bone resorption or biological complications, similar to what is observed with implants placed according to the conventional (late) protocol.
|
|
| 12. |
- Schropp, Lars, et al.
(författare)
-
Fate of the buccal bone at implants placed early, delayed, or late after tooth extraction analyzed by cone beam CT : 10-year results from a randomized, controlled, clinical study
- 2015
-
Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 26:5, s. 492-500
-
Tidskriftsartikel (refereegranskat)abstract
- AIM:To present 10-year cone beam CT (CBCT) data on the fate of buccal bone at single-tooth implants placed early, delayed, or late after tooth extraction. MATERIAL AND METHODS:Sixty-three of 72 patients, originally randomly allocated to three equal-size groups, received a single-tooth implant on average 10 days (Ea; N = 22), 3 months (De; N = 22), or 1.5 years (La; N = 19) after tooth extraction. Healing abutments were mounted after a 3-month period of submerged healing and metalceramic crowns were cemented after one additional month. At the second stage surgery, presence of buccal bone defects (dehiscences or intrabony) and their dimensions were registered. CBCT scans recorded with a Scanora(®) 3D unit and standardized periapical (PA) radiographs of the implants were obtained at the 10-year control. Interproximal bone levels (i.e., the distance from the implant platform to the first bone-to-implant contact; BIC) measured in CBCT image sections and PA were compared, and the buccal bone level was determined in the CBCT images. RESULTS:Two Ea and one De implants failed to osseointegrate. Forty-nine patients attended the 10-year control and due to poor quality of 5 CBCT scans, useful CBCT images were available from 44 patients (Ea:12, De:17, La:15). No significant differences between CBCT and PA images in measurements of the interproximal bone levels were observed. Ten years after implant placement, BIC at the buccal aspect was located on average 2 mm apically to the implant platform (2.39 ± 1.06 mm [median = 2.36] for Ea, 2.22 ± 0.99 mm [median = 2.16] for De, and 1.85 ± 0.65 mm [median = 1.95] for La implants) with no significant difference among the groups (P = 0.20). Mean buccal bone level (bBL) for implants with an intrabony or a dehiscence defect at second stage surgery was 2.51 ± 1.12 mm [median = 2.70] and 2.84 ± 0.70 mm [median = 2.79], respectively, while 1.78 ± 0.74 mm [median = 1.93] for the implants with no defect. The difference in bBL between the implants without a defect and those with a dehiscence was significant at 10 years (P = 0.0005). CONCLUSION:Time of placement of single-tooth implants after tooth extraction did not significantly influence the peri-implant buccal bone level, while presence of a buccal bone dehiscence at second stage surgery resulted in significantly more apically located BIC buccally at 10 years.
|
|
| 13. |
- Seiboth, Frank, et al.
(författare)
-
Aberration Correction for Hard X-ray Focusing at the Nanoscale
- 2017
-
Ingår i: Advances in X-Ray/EUV Optics and Components XII. - : SPIE - International Society for Optical Engineering. - 9781510612303 - 9781510612297
-
Konferensbidrag (refereegranskat)abstract
- We developed a corrective phase plate that enables the correction of residual aberration in reflective, diffractive, and refractive X-ray optics. The principle is demonstrated on a stack of beryllium compound refractive lenses with a numerical aperture of 0.49 x 10(-3) at three different synchrotron radiation and x-ray free-electron laser facilities. By introducing this phase plate into the beam path, we were able to correct the spherical aberration of the optical system and improve the Strehl ratio of the optics from 0.29(7) to 0.87(5), creating a diffraction-limited, large aperture, nanofocusing optics that is radiation resistant and very compact.
|
|
| 14. |
- Seiboth, Frank, et al.
(författare)
-
Perfect X-ray focusing via fitting corrective glasses to aberrated optics
- 2017
-
Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Due to their short wavelength, X-rays can in principle be focused down to a few nanometres and below. At the same time, it is this short wavelength that puts stringent requirements on X-ray optics and their metrology. Both are limited by today’s technology. In this work, we present accurate at wavelength measurements of residual aberrations of a refractive X-ray lens using ptychography to manufacture a corrective phase plate. Together with the fitted phase plate the optics shows diffraction-limited performance, generating a nearly Gaussian beam profile with a Strehl ratio above 0.8. This scheme can be applied to any other focusing optics, thus solving the X-ray optical problem at synchrotron radiation sources and X-ray free-electron lasers.
|
|
| 15. |
- Spin-Neto, Rubens, et al.
(författare)
-
Técnicas Radiográficas Aplicadas à Pesquisa em Implantodontia : Racionalização
- 2013
-
Ingår i: Excelência Clínica em Implantodontia. - : Quintessence. - 9788578890339 ; , s. 135-159
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A reabilitarção oral por meio de implantes de titânio como alternativa às próteses convencionais, para a substituirção de dentes ausentes ou perdi dos, é uma modalidade de tratamento rotineira. O exame radiográfico é um componente indispensável em todas as fases do tratamento com implan tes, incluindo o planejamento pré-operatório, o diagnóstico, a avaliarção do tratamento e o monitoramento longitudinal dos resultados. Apesar disso, o uso descontrolado de exames radiográficos leva a uma exposirção á radiarção aumentada e desnecessária aos pacientes, sendo imprescindível a correta indicarção de cada modalidade de exame sugerido, embasados sempre nas vantagens do uso do método selecionado, e principalmente, ponderados por suas limitarções. Ao longo dos últimos anos urna grandevariedade de técnicas de ima geologia bi (2D) e tridimensionais (3D) têm sido utilizadas tanto nas áreas clínicas como nas pré-clínicas em Implantodontia, estando conectadas ás várias fases da reabilitarção com implantes. Mais recentemente, os avanços tecnológicos e os custos mais atraentes fizeram com que as técnicas de imagem 3D se tornassem mais acessíveis para os cirurgiões-dentistas de uma forma geral. Como reflexo, a utilizarção de tomografias computadori zadas de feixe cônico (TCFC) é cadavez mais comum, devendo sempre ser levado em conta que o uso desta técnica está associado a um aumento na dose de radiação fornecida ao paciente1-4 e a custos mais elevados quando comparada a radiografias panorâmicas, por exemplo, aliado ao fato de que o acesso a TCFC ainda é bastante limitado para a maioria das clínicas, con siderando o Brasil como um todo.5 Além disso, esta tecnologia é util prin cipalmente para o diagnóstico e plano de tratamento com implantes, mas não para o monitoramento do tratamento, devido aos artefatos que apare- cem adjacentes à superfície do implante, como resultado da interferência de objetos metálicos na captação dessas imagens. Por outro lado, admite -se que esta tecnologia provavelmente se tornará o padrão diagnóstico em um futuro próximo, tal como já ocorre em algumas partes do mundo. Considerando o que é exposto acima, neste capítulo discutiremos alguns aspectos relevantes da radiografia 2D, com foco em pesquisas em Implantodontia. As técnicas radiográficas em 3D serão brevemente men cionadas em relação à radiografia 2D. Mais especificamente, as questões relacionadas à confiabilidade das medidas radiográficas para estimar o nível ósseo peri-implantar (a), a geometria de projeção para qualidade apropriada das imagens de implantes e para avaliação do nível ósseo peri -implantar (b), distorçães dimensionais em radiografias periapicais e panorâmicas (c) e os prazos de exame radiográfico para avaliação longitu dinal dos níveis ósseos peri-implantares (d) serão discutidos.
|
|
| 16. |
- Stavropoulos, Andreas, et al.
(författare)
-
Biological complications after early/delayed/late implant placement : 10-year results from a RCT
- 2013
-
Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 24:s9, s. 38-38
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Limited information is available on the influence of timing of implant placement after tooth extraction on the marginal peri-implant conditions in the long-term. Aim/Hypothesis: To report on the marginal peri-implant soft and hard tissue levels, including prevalence of peri-implant mucositis and peri-implantitis, 10 years after early (Ea), delayed (De), or late (La) implant placement. Material and methods: 64 patients, previously randomly allocated, received a single-tooth implant (Osseotite, 3i Biomet) on average 10 days (Ea: 23), 3 months (De: 22), or 12 months (La: 19) after tooth extraction. Second stage surgery was performed after 3–4 months and porcelain-fused-to-metal crowns were cemented on the implants after one additional month (TC). All patients were recalled for a clinical and radiographic examination approximately one (T1) and 10 years (T10) after implant installation. Marginal peri-implant bone levels (BL) were measured on orthogonal periapical radiographs at TC, T1, and T10. Differences among the implant placement protocols were tested by Anova and chi-square tests. Results: At T10, clinical and radiographic data were available from 49 and 48 patients, respectively; 47 patients attended all controls, while radiographic data from all visits were available for 39 patients. Proximal BL for all implants was located at 1.39 0.65 mm, 1.32 0.63 mm, and 1.38 0.98 mm apically to the implant shoulder, at TC, T1, and T10, respectively. No significant differences in proximal BL were found among the groups at TC and T10. At T1, BL was located more apically at De implants (1.71 mm) compared to Ea and La implants (1.09 and 0.99 mm, respectively) (P = 0.002). No significant differences in BL were found between TC and T10 or between T1 and T10 both regarding all implants and within each group. 55% and 47% of the implants showed at least one site with a probing depth (PD) ≥5 mm at TC and T1, respectively. At T10, 70% of the implants showed bleeding or pus on probing (BoP) and 36% of the implants showed one or more sites with PD ≥5 mm; no significant differences among the groups were seen. At T10, only two implants (De and La) (4.3%) suffered from peri-implantitis defined as PD ≥5 mm, BoP, and marginal bone loss of >1 mm from TC. Conclusions and clinical implications: Timing of implant placement after tooth extraction did not significantly influence the marginal peri-implant soft and hard tissue levels in the longterm. Peri-implant mucositis was a frequent finding, while peri-implantitis was only scarce. This study was partially supported by 3i Biomet, FL, USA.
|
|
| 17. |
- Weber, Sebastian, et al.
(författare)
-
Evolution of Hierarchically Porous Nickel Alumina Catalysts Studied by X-Ray Ptychography
- 2022
-
Ingår i: Advanced science (Weinheim, Baden-Wurttemberg, Germany). - : Wiley. - 2198-3844. ; 9:8, s. 2105432-2105432
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis of hierarchically porous materials usually requires complex experimental procedures, often based around extensive trial and error approaches. One common synthesis strategy is the sol-gel method, although the relation between synthesis parameters, material structure and function has not been widely explored. Here, in situ 2D hard X-ray ptychography (XRP) and 3D ptychographic X-ray computed tomography (PXCT) are applied to monitor the development of hierarchical porosity in Ni/Al2 O3 and Al2 O3 catalysts with connected meso- and macropore networks. In situ XRP allows to follow textural changes of a dried gel Ni/Al2 O3 sample as a function of temperature during calcination, activation and CO2 methanation reaction. Complementary PXCT studies on dried gel particles of Ni/Al2 O3 and Al2 O3 provide quantitative information on pore structure, size distribution, and shape with 3D spatial resolution approaching 50 nm, while identical particles are imaged ex situ before and after calcination. The X-ray imaging results are correlated with N2 -sorption, Hg porosimetry and He pycnometry pore characterization. Hard X-ray nanotomography is highlighted to derive fine structural details including tortuosity, branching nodes, and closed pores, which are relevant in understanding transport phenomena during chemical reactions. XRP and PXCT are enabling technologies to understand complex synthesis pathways of porous materials.
|
|
| 18. |
- Yang, Xiaogang, et al.
(författare)
-
Tomographic reconstruction with a generative adversarial network
- 2020
-
Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 27, s. 486-493
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a deep learning algorithm for tomographic reconstruction (GANrec). The algorithm uses a generative adversarial network (GAN) to solve the inverse of the Radon transform directly. It works for independent sinograms without additional training steps. The GAN has been developed to fit the input sinogram with the model sinogram generated from the predicted reconstruction. Good quality reconstructions can be obtained during the minimization of the fitting errors. The reconstruction is a self-Training procedure based on the physics model, instead of on training data. The algorithm showed significant improvements in the reconstruction accuracy, especially for missing-wedge tomography acquired at less than 180° rotational range. It was also validated by reconstructing a missing-wedge X-ray ptychographic tomography (PXCT) data set of a macroporous zeolite particle, for which only 51 projections over 70° could be collected. The GANrec recovered the 3D pore structure with reasonable quality for further analysis. This reconstruction concept can work universally for most of the ill-posed inverse problems if the forward model is well defined, such as phase retrieval of in-line phase-contrast imaging.
|
|
