Effect of titanium and stainless steel posts in detection of vertical root fractures using NewTom VG cone beam computed tomography system

Mohammadpour, Mahdis,Bakhshalian, Neema,Shahab, Shahriar,Sadeghi, Shaya,Ataee, Mona,Sarikhani, Soodeh Korean Academy of Oral and Maxillofacial Radiology 2014 Imaging Science in Dentistry Vol.44 No.2

Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.

Effect of titanium and stainless steel posts in detection of vertical root fractures using NewTom VG cone beam computed tomography system

Mahdis Mohammadpour,Neema Bakhshalian,Shahriar Shahab,Shaya Sadeghi,Soodeh Sarikhani 대한영상치의학회 2014 Imaging Science in Dentistry Vol.44 No.2

Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.

A novel ternary Pd-GO/N-doped TiO2 hierarchical visible-light sensitive photocatalyst for nanocomposite membrane

Hossein Mahdavi,Mahdi Rezaei,Leila Ahmadian-Alam,Mostafa Mohammadpour Amini 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.6

We investigated the visible-light sensitive photocatalytic ability of a designed ternary Pd-GO/TiON nanocomposite for use as an effective photocatalyst in membranes. We succeeded in synthesizing the TiO2-based photocatalyst for Suzuki coupling reaction and application of this photocatalyst for fabricating high performance photocatalytic membrane. In this regard, palladium metal as a complementary metal in combination with N-doped TiO2 (TiON) and graphene oxide (GO) nanosheets was utilized to synthesize the upgraded version of the visible light sensitive nanocomposite photocatalyst. The synthesis of Pd-GO/TiON hierarchical nanostructure was confirmed by detecting Ti, Pd, C, O and N elements by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and EDX mapping analysis. Then, a series of PVDF-based photocatalytic nanocomposite membranes (PhNMs) filled with Pd-GO/TiON was fabricated. Evaluating the yield of Pd-GO/TiON photocatalyst was around 99% and 70% for heterogeneous system and the prepared PhNM containing 3% Pd-GO/TiON, respectively. Although, yield of Pd-GO/TiON photocatalyst in membrane is not comparable with the high yield reported by other researchers in heterogeneous system; however, it can be considered as a valuable result because of the importance of photocatalytic reactions and the environmental advantages of membrane technology. Furthermore, various analyses were also performed to study the synthesized photocatalysts and the prepared photocatalytic membranes, including thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and diffuse reflectance spectrophotometry (DRS).

Analysis of the hydrodynamic torque effects on large size butterfly valves andcomparing results with AWWA C504 standard recommendations

Farid Vakili-Tahami,Mohammad Zehsaz,Mahdi Mohammadpour,Ali Vakili-Tahami 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9

Butterfly valves are widely used in various industries such as water distribution, sewage, oil and gas plants. The hydrodynamic torque applied on the butterfly valve disk is one of the most important factors which should be considered in their design and application. Although several methods have been used to calculate the total torque on these valves, most of them are based on hydrostatic analysis and ignore the hydrodynamic effect which has a major role to determine the torque of the large-size valves. For finding the dynamic-valvetorque,some empirical formulas and methods have been proposed; for example in AWWA C504 standard, a relationship for calculating the dynamic torque has been given and its variation versus disk angle has been stated. However, the use of these empirical relationships is restricted due to the conditions defined in the standards. In this paper, the dynamic-valve-torque has been calculated for a large butterfly valve under different conditions and also at the different opening angles of the valve disk. For this purpose a computational fluid dynamics (CFD) method has been used. The results have been compared with those given in the AWWA C504 standard recommendations. Moreover, the effects of the disk shape and its deformation, surface roughness, upstream/downstream pressure variation and disk-offset value have been studied.

Accuracy of linear measurement using cone-beam computed tomography at different reconstruction angles

Sima Nikneshan,Shadi Hamidi Aval,Neema Bakhshalian,Shahriyar Shahab,Mahdis Mohammadpour,Soodeh Sarikhani 대한영상치의학회 2014 Imaging Science in Dentistry Vol.44 No.4

Purpose: This study was performed to evaluate the effect of changing the orientation of a reconstructed image on the accuracy of linear measurements using cone-beam computed tomography (CBCT). Materials and Methods: Forty-two titanium pins were inserted in seven dry sheep mandibles. The length of these pins was measured using a digital caliper with readability of 0.01 mm. Mandibles were radiographed using a CBCT device. When the CBCT images were reconstructed, the orientation of slices was adjusted to parallel (i.e., 0˚), +10˚, +12˚, -12˚, and -10˚with respect to the occlusal plane. The length of the pins was measured by three radiologists, and the accuracy of these measurements was reported using descriptive statistics and one-way analysis of variance (ANOVA); p⁄0.05 was considered statistically significant. Results: The differences in radiographic measurements ranged from -0.64 to +0.06 at the orientation of -12˚, -0.66 to -0.11 at -10˚, -0.51 to +0.19 at 0˚, -0.64 to +0.08 at +10˚, and -0.64 to +0.1 at +12˚. The mean absolute values of the errors were greater at negative orientations than at the parallel position or at positive orientations. The observers underestimated most of the variables by 0.5-0.1 mm (83.6%). In the second set of observations, the reproducibility at all orientations was greater than 0.9. Conclusion: Changing the slice orientation in the range of -12˚to +12˚reduced the accuracy of linear measurements obtained using CBCT. However, the error value was smaller than 0.5 mm and was, therefore, clinically acceptable.

Accuracy of linear measurement using cone-beam computed tomography at different reconstruction angles

Nikneshan, Sima,Aval, Shadi Hamidi,Bakhshalian, Neema,Shahab, Shahriyar,Mohammadpour, Mahdis,Sarikhani, Soodeh Korean Academy of Oral and Maxillofacial Radiology 2014 Imaging Science in Dentistry Vol.44 No.4

Purpose: This study was performed to evaluate the effect of changing the orientation of a reconstructed image on the accuracy of linear measurements using cone-beam computed tomography (CBCT). Materials and Methods: Forty-two titanium pins were inserted in seven dry sheep mandibles. The length of these pins was measured using a digital caliper with readability of 0.01 mm. Mandibles were radiographed using a CBCT device. When the CBCT images were reconstructed, the orientation of slices was adjusted to parallel (i.e., $0^{\circ}$), $+10^{\circ}$, $+12^{\circ}$, $-12^{\circ}$, and $-10^{\circ}$ with respect to the occlusal plane. The length of the pins was measured by three radiologists, and the accuracy of these measurements was reported using descriptive statistics and one-way analysis of variance (ANOVA); p<0.05 was considered statistically significant. Results: The differences in radiographic measurements ranged from -0.64 to +0.06 at the orientation of $-12^{\circ}$, -0.66 to -0.11 at $-10^{\circ}$, -0.51 to +0.19 at $0^{\circ}$, -0.64 to +0.08 at $+10^{\circ}$, and -0.64 to +0.1 at $+12^{\circ}$. The mean absolute values of the errors were greater at negative orientations than at the parallel position or at positive orientations. The observers underestimated most of the variables by 0.5-0.1 mm (83.6%). In the second set of observations, the reproducibility at all orientations was greater than 0.9. Conclusion: Changing the slice orientation in the range of $-12^{\circ}$ to $+12^{\circ}$ reduced the accuracy of linear measurements obtained using CBCT. However, the error value was smaller than 0.5 mm and was, therefore, clinically acceptable.