The effect of radiotherapy on survival of dental implants in head and neck cancer patients

Objectives: To explore the current literature of the survival of dental implants in irradiated head and neck cancer patients considering the role of implant location, bone augmentation, dose of radiation and timing of implant placement. Study Design: Pubmed search was conducted to identify articles published between January 2000 and December 2014 and presenting data of dental implant survival with radiotherapy in head and neck cancer patients. Studies on animal subjects and craniofacial implants were excluded. Results: 18 articles out of 27 were eligible for inclusion in this systematic review. 12 out of 18 studies reported favorable outcome of dental implants and radiotherapy with survival rates between 74.4% and 97%. Seven out of ten studies comparing the survival rates according to site of implant placement reported that implants were found to osseointegrate with greater success in the irradiated mandible than irradiated maxilla. 5 studies which compared implant survival in irradiated native bone versus irradiated grafted bone reported that irradiated grafted bone showed a significantly reduced dental implant survival rate in comparison to irradiated native bone. 6 out of 18studies in which radiation doses exceeded 70 Gy reported lower survival rates of dental implants in comparison to the studies in which radiation doses were ≤70Gy. Higher survival rates were reported in 2 studies in which implants placement was before radiotherapy in comparison to the remaining 16 studies in which implants placement was after radiotherapy. Conclusions: Dental implants may be affected by radiotherapy especially when they are placed in maxilla, in grafted bone, or after radiation, however, they remain a functional option for rehabilitation of head and cancer patients. More prospective cohort studies and randomized controlled trails are still needed to draw more evidence based conclusion

Uncertainty and Volatility in MENA Stock Markets During the Arab Spring

This paper sheds light on the economic impacts of political uncertainty caused by the civil uprisings that swept across the Arab World and have been collectively known as the Arab Spring. Measuring documented effects of political uncertainty on regional stock market indices, we examine the impact of the Arab Spring on the volatility of stock markets in eight countries in the Middle East and North Africa (MENA) region: Egypt, Lebanon, Jordon, United Arab Emirate, Qatar, Bahrain, Oman and Kuwait. This analysis also permits testing the existence of financial contagion among equity markets in the MENA region during the Arab Spring. To capture the time-varying and multi-horizon nature of the evidence of volatility and contagion in the eight MENA stock markets, we apply two robust methodologies on data from November 2008 to March 2014: MGARCH-DCC, Continuous Wavelet Transforms (CWT). Our results tend to indicate two key findings. First, the discrepancies between the volatile stock markets of countries directly impacted by the Arab Spring and the countries that were not directly impacted indicate that international investors may still enjoy portfolio diversification and investment in MENA markets. Second, the lack of financial contagion during the Arab Spring suggests that there is little evidence of cointegration among MENA markets implying the opportunities of portfolio diversification. Providing a general analysis of the economic situation and the investment climate in the MENA region during and after the Arab Spring, this study bears significant importance for the policy makers, local and international investors, and market regulators

Uncertainty and Volatility in MENA Stock Markets During the Arab Spring

This paper sheds light on the economic impacts of political uncertainty caused by the civil uprisings that swept across the Arab World and have been collectively known as the Arab Spring. Measuring documented effects of political uncertainty on regional stock market indices, we examine the impact of the Arab Spring on the volatility of stock markets in eight countries in the Middle East and North Africa (MENA) region: Egypt, Lebanon, Jordon, United Arab Emirate, Qatar, Bahrain, Oman and Kuwait. This analysis also permits testing the existence of financial contagion among equity markets in the MENA region during the Arab Spring. To capture the time-varying and multi-horizon nature of the evidence of volatility and contagion in the eight MENA stock markets, we apply two robust methodologies on data from November 2008 to March 2014: MGARCH-DCC, Continuous Wavelet Transforms (CWT). Our results tend to indicate two key findings. First, the discrepancies between the volatile stock markets of countries directly impacted by the Arab Spring and the countries that were not directly impacted indicate that international investors may still enjoy portfolio diversification and investment in MENA markets. Second, the lack of financial contagion during the Arab Spring suggests that there is little evidence of cointegration among MENA markets implying the opportunities of portfolio diversification. Providing a general analysis of the economic situation and the investment climate in the MENA region during and after the Arab Spring, this study bears significant importance for the policy makers, local and international investors, and market regulators

Free–Free Beam Resting on Tensionless Elastic Foundation Subjected to Patch Load

Despite the popularity of a completely free beam resting on a tensionless foundation in the construction industry, the existing bending analysis solutions are limited to certain types of loads (mostly point and uniformly distributed loads); these are also quite complex for practicing engineers to handle. To overcome the associated complexity, a simple iterative procedure is developed in this study, which uses the Ritz method for the bending analysis of a free–free beam on a tensionless foundation subjected to a patched load. The Ritz method formulation is first presented with polynomials being used to approximate the beam deflection with unknown constants to be determined through minimization of the potential energy. To account for the tensionless action, the subgrade reaction is set to zero when the deflection is negative. The non-zero subgrade reaction zone is defined by αlL/2<x<αrL/2 where the coefficients αl and αr are to be determined iteratively. A numerical example is presented to illustrate the applicability of the proposed procedure for symmetrical and asymmetrical problems. The obtained results show high negative deflection, which proves the occurrence of separation between the beam and the supporting tensionless foundation. This location of negative deflection is called the lifted zone, while the point that separates between the negative and positive deflection is called the lift-off point. A parametric study is then performed to study the effect of the amount of load, stiffness of the beam, and the subgrade reaction on the length of the lifted zone. The results of the parametric study indicate that for the same beam stiffness to subgrade reaction modulus ratio (EI/k), the lift-off point remains the same and beams with lower stiffnesses or higher loads deflect more

Ritz method for large deflection of orthotropic thin plates with mixed boundary conditions

In this paper, the Ritz method is developed for the analysis of thin rectangular orthotropic plates undergoing large deflection. The trial functions approximating the plate lateral and in-plane displacements are represented by simple polynomials. The nonlinear algebraic equations resulting from the application of the concept of minimum potential energy of the orthotropic plate are cast in a matrix form. The developed matrix form equations are then implemented in a Mathematica code that allows for the automation of the solution for an arbitrary number of the trial polynomials. The developed code is tested through several numerical examples involving rectangular plates with different aspect ratios and boundary conditions. The results of all examples demonstrate the efficiency and accuracy of the proposed method

Free–Free Beam Resting on Tensionless Elastic Foundation Subjected to Patch Load

Despite the popularity of a completely free beam resting on a tensionless foundation in the construction industry, the existing bending analysis solutions are limited to certain types of loads (mostly point and uniformly distributed loads); these are also quite complex for practicing engineers to handle. To overcome the associated complexity, a simple iterative procedure is developed in this study, which uses the Ritz method for the bending analysis of a free–free beam on a tensionless foundation subjected to a patched load. The Ritz method formulation is first presented with polynomials being used to approximate the beam deflection with unknown constants to be determined through minimization of the potential energy. To account for the tensionless action, the subgrade reaction is set to zero when the deflection is negative. The non-zero subgrade reaction zone is defined by αlL/2xαrL/2 where the coefficients αl and αr are to be determined iteratively. A numerical example is presented to illustrate the applicability of the proposed procedure for symmetrical and asymmetrical problems. The obtained results show high negative deflection, which proves the occurrence of separation between the beam and the supporting tensionless foundation. This location of negative deflection is called the lifted zone, while the point that separates between the negative and positive deflection is called the lift-off point. A parametric study is then performed to study the effect of the amount of load, stiffness of the beam, and the subgrade reaction on the length of the lifted zone. The results of the parametric study indicate that for the same beam stiffness to subgrade reaction modulus ratio (EI/k), the lift-off point remains the same and beams with lower stiffnesses or higher loads deflect more

Enhancing unreinforced masonry wall resilience through nano-silica modified steel fiber reinforced mortar: A study on in-plane cyclic loading

Strengthening existing unreinforced masonry (URM) structures with plaster is a common technique used to improve the structural integrity and durability of buildings. However, using a thin layer of plaster alone may not provide sufficient reinforcement to adequately enhance the URM wall’s resistance to lateral or other types of loading. Therefore, incorporating additional materials, such as steel fibers and nano-silica, into the plaster mix has been explored in this study to further improve the URM wall’s resilience performance. The effect of nano-silica modified steel fibers reinforced (NS-SFR) mortar plastering on the axial and lateral load capacity of concrete masonry walls was experimentally investigated. The investigated URM walls were constructed with a dimension of 830 × 810 × 100 mm (length × width × thickness) using hollow concrete masonry blocks. These walls were categorized as a reference wall, plastered on one side only wall, and plastered on both sides wall. During the experimental testing, each sample was exposed to a combination of precompression and cyclic in-plane loading to assess its shear capacity. The tests also involved closely observing and identifying any cracks or types of failures that occurred. The results of the tests indicated that the walls that were strengthened with NS-SFR mortar exhibited a significant improvement in their compressive strength, shear strength capacity, and stiffness, in comparison to the walls that were not strengthened. Applying NS-SFR mortar as a plaster on the URM wall resulted in significant improvements in both compressive strength and shear capacity. Specifically, for the one-side plastered wall, the use of NS-SFR mortar increased compressive strength and shear capacity by 18.5 % and 40 %, respectively, while for the two sides plastered wall, the increase was even more significant, with improvements of 86.5 % and 132 % in compressive strength and shear capacity, respectively

Infektionsprävention: Wissen und Compliance bei Studenten der Zahnmedizin

Objective: This study aimed to assess the level of knowledge, attitudes, and practices regarding infection control procedures among undergraduate dental students. Methods: This was a questionnaire-based cross-sectional survey. A self-administered questionnaire consisting of questions on students' vaccination status as well as knowledge and attitudes regarding infection control was sent to 600 undergraduate dental students in the fourth, fifth, and sixth year of the Al-Farabi College for Dentistry and Nursing, Riyadh, Saudi Arabia. The collected data were analyzed using SPSS software. The significance level was set at P <0.05. Results: The response rate was 85% (512 out of 600). While the vast majority of students (90%) had been vaccinated against hepatitis, only 37.4% have been assessed for anti-HBs. A total of 98.8% and 90.8% reported always wearing gloves and masks, respectively, during dental procedures. The use of protective eyewear was reported by only 29.2%. A significantly higher proportion of sixth-year students showed a positive attitude toward the treatment of patients with infectious diseases than other students of lower academic years. Approximately one-third of students reported having one or more occupational injuries while treating their patients. Conclusion: Although the students had good knowledge and attitudes regarding infection control, the compliance and practice levels regarding the same were low. Such findings highlight the necessity of continued infection-control education of Saudi dental students.Zielsetzung: In der Studie sollten die Kenntnisse, die Einstellung und die praktische Umsetzung infektionspräventiver Maßnahmen bei Studenten der Zahnmedizin analysiert werden.Methode: In einer Querschnittsstudie wurde ein selbst zu beantwortender Fragebogen zur Erfassung des Impfstatus, der Kenntnisse und der Einstellung zur Infektionsprävention an 600 Studenten im 4., 5. und 6. Ausbildungsjahr des Al-Farabi College für Dentistry und Nursing, Riyadh, Saudi Arabia, verschickt. Die Daten wurden mittels SPSS analysiert. Das Signifikanzniveau wurde mit p<0,05 festgelegt.Ergebnisse: Die Responserate betrug 85% (512 von 600). Während die Mehrzahl der Studenten (90%) gegen Hepatitis B geimpft war, war nur bei 37,4% anti-HBs bestimmt worden. 98,8% bzw. 90,8% trugen stets Schutzhandschuhe bzw. Mund-Nasen-Schutz bei der zahnärztlichen Behandlung, während das Tragen einer Schutzbrille nur in 29,2% angegeben wurde. Ein signifikant höherer Anteil der Studenten zeigte im 6. Ausbildungsjahr eine positive Einstellung zur Behandlung von Patienten mit Infektionskrankheiten im Vergleich zum 4. und 5. Ausbildungsjahr. Etwa ein Drittel der Studenten gab an, dass sich ein oder mehrere arbeitsbedingte Verletzungen bei der Patientenbehandlung ereignet hatten.Schlussfolgerung: Obwohl die Studenten ein solides Wissen und eine gute Einstellung zur Infektionsprävention hatten, war die Compliance zur praktischen Umsetzung gering. Die Ergebnisse unterstreichen die Notwendigkeit der kontinuierlichen Erziehung Saudischer Zahnmedizinstudenten zur Infektionsprävention

Outcomes and problems of hysteroscopic endometrial ablation in a University Hospital

Objective: To evaluate outcomes and hysteroscopic endometrial ablation challenge in Assuit University Hospital. Study design: Descriptive study. Setting: Woman’s Health Hospital a tertiary health center in upper Egypt. Patients: Fifty premenopausal women complaining of dysfunction uterine bleeding. Primary outcome measured: Number of occasions where hysteroscopic endometrial ablation was achieved without intra-operative or technical complications. Secondary outcome measured: (1) Number of occasions where hysteroscopic endometrial ablation was not possible. (2) Causes of inability to achieve hysteroscopic endometrial ablation and methods used to overcome these causes. (3) Postoperative outcomes at 1 year follow up. Results: Among 50 premenopausal women included in the study, hysteroscopic endometrial ablation was achieved in 41 cases (82%), 31 (62%) cases of them by the primary prepared hysteroscopic instruments and 10 cases (20%) by backup instruments. Tactile endometrial ablation was used as a backup method for hysteroscopic failures in 8 (16%) cases; and one (2%) woman had undergone a hysterectomy. Conclusion: Although hysteroscopic endometrial ablation is simple and feasible procedure, yet due to financial constrains in many occasions inability to complete the procedure as was intended can occur

Tactile Electrosurgical Ablation: A Technique for the Treatment of Intractable Heavy and Prolonged Menstrual Bleeding

Objective. To study the efficacy and safety of tactile electrosurgical ablation (TEA) in stopping a persistent attack of abnormal uterine bleeding not responding to medical and hormonal therapy. Methods. This is a case series of 19 cases with intractable abnormal uterine bleeding, who underwent TEA at the Women’s Health Center of Assiut University. The outcomes measured were; patient’s acceptability, operative time, complications, menstrual outcomes, and reintervention. Results. None of the 19 counseled cases refused the TEA procedure which took 6–10 minutes without intraoperative complications. The procedure was successful in the immediate cessation of bleeding in 18 out of 19 cases. During the 24-month follow-up period, 9 cases developed amenorrhea, 5 had scanty menstrual bleeding, 3 were regularly menstruating, 1 case underwent repeat TEA ablation, and one underwent a hysterectomy. Conclusions. TEA represents a safe, inexpensive, and successful method for management of uterine bleeding emergencies with additional long-term beneficial effects. However, more studies with more cases and longer follow-up periods are warranted