Influence of CBCT parameters on image quality and the diagnosis of vertical root fractures in teeth with metallic posts: an ex vivo study

Lagos de Melo Larissa Pereira,Queiroz Polyane Mazucatto,Moreira-Souza Larissa,Nadaes Mariana Rocha,Santaella Gustavo Machado,Oliveira Matheus Lima,Freitas Deborah Queiroz 대한치과보존학회 2023 Restorative Dentistry & Endodontics Vol.48 No.2

Objectives The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF. Objectives The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

The effects of different metal posts, cements, and exposure parameters on cone-beam computed tomography artifacts

Freitas Ana Priscila Lira de Farias,Peixoto Larissa Rangel,Mariz Suassuna Fernanda Clotilde,Bento Patrícia Meira,Maia Amorim Ana Marly Araújo,Rovaris Silva Karla,de Almeida Barros Renata Quirino,Pontu 대한영상치의학회 2023 Imaging Science in Dentistry Vol.53 No.2

Purpose: This study assessed the intensity of artifacts produced by 2 metal posts, 2 cements, and different exposure parameters using 2 cone-beam computed tomography (CBCT) units. Materials and Methods: The sample was composed of 20 single-rooted premolars, divided into 4 groups: Ni-Cr/ zinc phosphate, Ni-Cr/resin cement, Ag-Pd/zinc phosphate, and Ag-Pd/resin cement. Samples were scanned before and after post insertion and cementation using a CS9000 3D scanner with 4 exposure parameters (85/90 kV and 6.3/10 mA) and an i-CAT scanner with 120 kV and 5 mA. The presence of artifacts was assessed subjectively by 2 observers and objectively by a trained observer using ImageJ software. The Mann-Whitney, Wilcoxon, weighted kappa, and chi-square tests were used to assess data at a 95% confidence level (α<0.05). Results: In the subjective analyses, AgPd presented more hypodense and hyperdense lines than NiCr (P<0.05), and more hypodense halos were found using i-CAT (P<0.05) than using CS9000 3D. More hypodense halos, hypodense lines, and hyperdense lines were observed at 10 mA than at 6.3 mA (P<0.05). More hypodense halos were observed at 85 kV than at 90 kV (P<0.05). CS9000 3D presented more hypodense and hyperdense lines than i-CAT (P<0.05). In the objective analyses, AgPd presented higher percentages of hyperdense and hypodense artifacts than NiCr (P<0.05). Zinc phosphate cement presented higher hyperdense artifact percentages on CS9000 3D scans (P<0.05). CS9000 3D presented higher artifact percentages than i-CAT (P<0.05). Conclusion: High-atomic-number alloys, higher tube current, and lower tube voltage may increase the artifacts present in CBCT images.

Multi-mixture herbicides provide management strategies in the control of the aquatic weed Heteranthera reniformis

Úrsula R. Zaidan,Larissa M. Motta,Wendel M. de Souza,Rodrigo M. Faria,Maria C. G. Paiva,Kassio F. Mendes,Francisco Cláudio L. de Freitas 한국작물학회 2021 Journal of crop science and biotechnology Vol.24 No.2

Heteranthera reniformis (mud plantain) is a weed of aquatic habit, which currently causes losses in the production of ornamental plants and irrigated crops, such as rice, and for which there are no herbicides registered in Brazil with proven control effectiveness. This study evaluated the control effectiveness of individual and multi-mixture herbicides (i.e., glyphosate, 2,4-D, triclopyr, paraquat, oxyfluorfen, sulfentrazone, carfentrazone, diuron and S-metolachor) on post-emergence of mud plantain. An organosilicone spreader adjuvant was also evaluated. Weed injury assessments were carried out over time, at 7, 14, 21, 42, and 60 days after application (DAA) of the herbicides. At the end of the study (60 DAA), the weed dry matter was measured. The progress of weed injury was modeled using a time-trend decomposition procedure based on the Locally Eighted Scatterplot Smoothing (LOESS) method. Treatments with glyphosate application proved to be more effective in relation to mud plantain injury over time, with a slight emphasis on treatments associated with triclopyr. However, evaluating the dry matter, the treatment with glyphosate alone was more effective; besides, it showed short-range injury variance in the control of H. reniformis . The inclusion of organosilicone adjuvant to some treatments was not quite successful. Regardless of the herbicide used, higher levels of initial injury are a fair predictor of fi nal control effectiveness (i.e., period after the herbicide eff ect). On the other hand, less initial injury corresponded directly to low control effectiveness. The results suggest that the herbicides, glyphosate, triclopyr, and carfentrazone, are suitable for mud-plantain control.

A fluidized bed reactor as an approach to enzymatic biodiesel production in a process with simultaneous glycerol removal

Weriton R.R. Fidalgo,Annie Ceron,Larissa Freitas,Ju´ lio C. Santos,Heizir F. de Castro 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.38 No.-

The hydrodynamic characteristics and operational conditions to produce biodiesel by the ethanolysis ofbabassu oil catalyzed by immobilized lipase (Novozym1 435) were established in a fluidized bed reactorcoupling with a column to simultaneous remove glycerol formed as byproduct. Hydrodynamics wasdetermined by means of pulse tracer trials and results showed that the flow pattern can be described asan ideal continuous flow stirred tank. The best performance was obtained by running the reactor withbiocatalyst loading of 12% and a space–time of 8 h, attaining an average yield of 98.1% and productivity of9.9 molester/gcat/min.