Ahmet Kurt - Academia.edu (original) (raw)

Papers by Ahmet Kurt

Research paper thumbnail of Neonates with Culture Proven Sepsis Have Lower Amounts and Percentage of CD45RA+ T Cells

Inflammation, 2008

To evaluate the expression of lymphocyte subsets in newborns diagnosed as culture proven or cultu... more To evaluate the expression of lymphocyte subsets in newborns diagnosed as culture proven or culture negative sepsis and to investigate the differentiation. The aim of this study is to explore neonatal immunology in newborns diagnosed as culture proven or culture negative neonatal sepsis and to identify their place in the diagnosis. This prospective study was performed in newborns who were diagnosed as neonatal sepsis and hospitalized in a tertiary care hospital and who were classified as culture proven sepsis (n = 12), as culture negative sepsis (n = 21) and healthy (n = 17). Lymphocyte subsets were obtained at time of diagnosis. Culture proven sepsis had statistically significant increase of WBC compared to culture negative sepsis and control groups (p p + was lower in culture proven sepsis and absolute count of CD4+ was lower in culture negative sepsis (p + were lower in culture negative sepsis than control and percentage of CD45RA+ was lower in culture proven sepsis than control (p CD45RO+ was higher in culture proven sepsis than control group (p

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Sokakta Çal›flan ya da Yaflayan Çocuklarda Sigara Alkol ve Madde Kullanma Prevelans› ve Etkileyen Faktörler

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Prevalence and factors affecting headache in Turkish schoolchildren

Pediatrics International, 2005

AbstractBackground: Headache is a public health problem affecting life quality negatively. The pr... more AbstractBackground: Headache is a public health problem affecting life quality negatively. The present cross-sectional, selective (2nd–5th grades) study was conducted to determine the prevalence of recurrent headache in schoolchildren in Mersin, a city of Turkey.Methods: A stratified sample of 5777 students was selected to be representative of the city's schoolchildren population. After the data quality control process, the study sample was reduced to 5562 schoolchildren.Result: The prevalence of recurrent headache was 49.2% (2739/5562). Among the studied population 24.7% had tension-type headache and 10.4% had migraine. Girls had significantly more frequent headache than boys. Binary logistic regression analysis found that increasing age, female gender, low socioeconomic status of family, low education level of mother, and positive family history of headache (father, mother, siblings, second degree relatives) had a statistically significant effect on the presence of headache in children. Additionally, having travel sickness had a statistically significant effect on schoolchildren headache (P = 0.000).Conclusion: Headache is a common health problem among schoolchildren in Mersin, which merits increased attention and detailed multicentre epidemiological and clinical studies.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A model for P300 generation based on responses to near-threshold visual stimuli

Cognitive Brain Research, 1999

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fetal growth restriction due to placental disease

Seminars in Perinatology, 2004

Normal fetal growth depends on the genetically predetermined growth potential and its modulation ... more Normal fetal growth depends on the genetically predetermined growth potential and its modulation by the health of the fetus, placenta and the mother. Fetuses that are small because of intrauterine growth restriction (IUGR) are at higher risk for poor perinatal and long-term outcome than those who are appropriately grown. Of the many potential underlying processes that may result in IUGR, placental disease is clinically the most relevant. Fetal cardiovascular and behavioral responses to placental insufficiency and the metabolic status are interrelated. The concurrent evaluation of fetal biometry, amniotic fluid volume, heart rate patterns, arterial and venous Doppler, and biophysical variables therefore allow the most comprehensive fetal evaluation in IUGR. In the absence of successful intrauterine therapy, the timing of delivery is perhaps the most critical aspect of the antenatal management. A discussion of the fetal responses to placental insufficiency and a management protocol that accounts for multiple Doppler and biophysical parameters as well as gestational age is provided in this review.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of Poly(ADP-Ribose) Polymerase Inhibition in Bladder Damage Caused by Cyclophosphamide in Rats

It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and ... more It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and peroxynitrite are responsible for cyclophosphamide (CP)-induced cystitis. Since endogenous production of peroxynitrite is known to lead to poly(ADP-ribose) polymerase (PARP) activation, in this study, the aim was to evaluate whether the PARP activation pathway is also included in the pathogenesis of CP-induced bladder ulceration in rats. A total of 48 male albino Wistar rats were divided into 5 groups. Group 1 served as control and was given 2 ml saline; four groups received a single dose of CP (200 mg/kg) with the same time intervals. Group 2 received CP only; Group 3, selective iNOS inhibitor 1400W (20 mg/kg); Group 4, peroxynitrite scavenger ebselen (30 mg/kg); and Group 5, PARP inhibitor 3-aminobenzamide (20 mg/kg). CP injection resulted in severe cystitis with continuous macroscopic hemorrhage, strong edema, inflammation, and ulceration. Moreover, bladder iNOS activation and urine nitrite-nitrate levels were dramatically increased. Histologically, 1400W protected bladder against CP damage and decreased urine nitrite-nitrate levels and bladder iNOS induction. Ebselen has shown similar histologic results with 1400W without changing urinary nitrite-nitrate level and iNOS activity. Furthermore in the 3-aminobenzamide group, beneficial effects had also occurred including decreased ulceration. These results suggest that PARP activation involves pathogenesis of CP-induced bladder ulceration. Furthermore, PARP is not only important for ulceration but also for bladder edema, hemorrhage, and inflammation because of broken uroepithelial cellular integrity.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of a Nonionic Surfactant on the Water Retention Properties of Unsaturated Soils

Soil Science Society of America Journal, 2001

Jm 2 while solid-liquid contact angle decreased from 40 to 10. No further changes in interfacial ... more Jm 2 while solid-liquid contact angle decreased from 40 to 10. No further changes in interfacial properties or soil water characteris- results in a lowering of both the surface tension of water tics were observed at surfactant concentrations above the CMC. The and the contact angle between the solid and aqueous experimental results were used to develop and evaluate alternative

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Decreased oxidation susceptibility of plasma low density lipoproteins in patients with Gilbert's syndrome

Journal of Gastroenterology and Hepatology, 2008

Background and Aim: The association of hyperbilirubinemia in Gilbert's syndrome (GS) with a decr... more Background and Aim: The association of hyperbilirubinemia in Gilbert's syndrome (GS) with a decrease in prevalence of coronary artery disease is a well-known phenomenon. In this study, the state of low-density lipoprotein (LDL) oxidation which has been postulated to be a significant determinant at the etiopathogenesis of atherosclerotic disorders was investigated among individuals with GS.Methods: For this purpose, serum cholesterol, LDL cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, apolipoprotein A and B, bilirubins, thiobarbituric acid-reactive substances, and the sensitivity of LDL oxidation levels, as well as serum alanine aminotransferase, aspartate aminotranserfase, gamma glutamil transferase, and alkaline phosphatase activities, were determined in 17 patients with Gilbert's syndrome and 15 healthy adults.Results: There was no significant difference between the groups except the indirect bilirubin parameter (P < 0.001). In comparison with the healthy individuals, LDL oxidation levels between 75 and 120 min were significantly lower (P < 0.005) along with prolonged lag-phase in GS patients, indicating a delay in oxidation susceptibility.Conclusion: It is suggested that the chronic hyperbilirubinemia leading to a lag-phase prolongation in LDL oxidation and a decrease in LDL oxidation may be reason for the low percentage of coronary artery disease.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Infrared and Raman study of some isonicotinic acid metal(II) halide and tetracyanonickelate complexes

Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Ameliorative Effects of Proanthocyanidin on Renal Ischemia/Reperfusion Injury

Renal Failure, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Biomechanical evaluation of a fiber-reinforced composite prosthesis supported by implants with and without a microthread collar design

Journal of Dental Sciences, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of different fixation methods following sagittal split ramus osteotomies using three-dimensional finite elements analysis

International Journal of Oral and Maxillofacial Surgery, 2005

The purpose of this study was to evaluate the mechanical behavior of different fixation methods u... more The purpose of this study was to evaluate the mechanical behavior of different fixation methods used in bilateral sagittal split ramus osteotomy (BSSRO). Part 1 comprises of the results of the analysis for mandibular advancement, four different fixation configurations of six hole fragmentation mini plates with monocortical screws and lag screws and posterior loading conditions in the molar and premolar region. The finite element analysis method (FEA) appears suitable for simulating complex mechanical stress situations in the maxillofacial region. The mechanical behavior of selected lag screws with linear or triangular configuration and double parallel or single oblique six hole mini plates with monocortical screws were compared by FEA after 5 mm BSSRO advancement procedure. Four separate three-dimensional finite element models of the mandible were created to simulate the BSSRO and corresponding fixation methods. These models consisted of 122,717 elements and 25,048 nodes. The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer&#39;s information. 500 N posterior occlusal loads were simulated on the distal segments. The commercial finite element solver MSC Marc software was utilized to calculate the stress fields on both the segments and fixative appliances. It was concluded that the use of 2.0mm lag screws placed in a triangular configuration following the BSSRO advancement surgery provides sufficient stability with any rotational movement and less stress fields at the osteotomy site, when compared with the other rigid fixation methods used in the current study.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA. Part 1: Advancement surgery

International Journal of Oral and Maxillofacial Surgery, 2008

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA

International Journal of Oral and Maxillofacial Surgery, 2009

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA

International Journal of Oral and Maxillofacial Surgery, 2009

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Three-dimensional finite element analysis used to compare methods of fixation after sagittal split ramus osteotomy: setback surgery-posterior loading

British Journal of Oral & Maxillofacial Surgery, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of prosthesis type and material on the stress distribution in bone around implants: A 3-dimensional finite element analysis

Journal of Dental Sciences, 2011

The design and materials of a prosthesis affect the loading of dental implants and deformation of... more The design and materials of a prosthesis affect the loading of dental implants and deformation of the bone. The aim of the study was to evaluate the effects of prosthesis design and materials on the stress distribution of implant-supported prostheses.A 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the bone. Three different models were designed as follows: a 3-unit implant-supported fixed partial denture (FPD) composed of a metal framework and porcelain veneer with (M2) or without a cantilevered extension (M1) and an FPD composed of a fiber-reinforced composite (FRC) framework and a particulate composite veneer without a cantilevered extension (M3). In separate load cases, 300-N vertical, 150-N oblique, and 60-N horizontal forces were applied to the prostheses in the models. von Mises stress values in the cortical and cancellous bone were calculated.In cortical bone, the highest von Mises stresses were noted in the M2 Model with a vertical load; whereas, higher stresses were observed in the M1 Model with horizontal and oblique loads. The lowest stress values were determined in the M3 Model for all loading conditions. In cancellous bone, decreased stress values were found with all 3 models under the applied loads.Prosthesis design and materials affect the load-transmission mechanism. Although additional experimental and clinical studies are needed, FRC FPDs can be considered a suitable alternative treatment choice for implant-supported prostheses. Within the limitations of the study, the 3-unit FPD supported by 2 implants with a cantilevered extension revealed acceptable stress distributions.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Biomechanical comparison of implant retained fixed partial dentures with fiber reinforced composite versus conventional metal frameworks: A 3D FEA study

Journal of The Mechanical Behavior of Biomedical Materials, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Neonates with Culture Proven Sepsis Have Lower Amounts and Percentage of CD45RA+ T Cells

Inflammation, 2008

To evaluate the expression of lymphocyte subsets in newborns diagnosed as culture proven or cultu... more To evaluate the expression of lymphocyte subsets in newborns diagnosed as culture proven or culture negative sepsis and to investigate the differentiation. The aim of this study is to explore neonatal immunology in newborns diagnosed as culture proven or culture negative neonatal sepsis and to identify their place in the diagnosis. This prospective study was performed in newborns who were diagnosed as neonatal sepsis and hospitalized in a tertiary care hospital and who were classified as culture proven sepsis (n = 12), as culture negative sepsis (n = 21) and healthy (n = 17). Lymphocyte subsets were obtained at time of diagnosis. Culture proven sepsis had statistically significant increase of WBC compared to culture negative sepsis and control groups (p p + was lower in culture proven sepsis and absolute count of CD4+ was lower in culture negative sepsis (p + were lower in culture negative sepsis than control and percentage of CD45RA+ was lower in culture proven sepsis than control (p CD45RO+ was higher in culture proven sepsis than control group (p

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Sokakta Çal›flan ya da Yaflayan Çocuklarda Sigara Alkol ve Madde Kullanma Prevelans› ve Etkileyen Faktörler

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Prevalence and factors affecting headache in Turkish schoolchildren

Pediatrics International, 2005

AbstractBackground: Headache is a public health problem affecting life quality negatively. The pr... more AbstractBackground: Headache is a public health problem affecting life quality negatively. The present cross-sectional, selective (2nd–5th grades) study was conducted to determine the prevalence of recurrent headache in schoolchildren in Mersin, a city of Turkey.Methods: A stratified sample of 5777 students was selected to be representative of the city's schoolchildren population. After the data quality control process, the study sample was reduced to 5562 schoolchildren.Result: The prevalence of recurrent headache was 49.2% (2739/5562). Among the studied population 24.7% had tension-type headache and 10.4% had migraine. Girls had significantly more frequent headache than boys. Binary logistic regression analysis found that increasing age, female gender, low socioeconomic status of family, low education level of mother, and positive family history of headache (father, mother, siblings, second degree relatives) had a statistically significant effect on the presence of headache in children. Additionally, having travel sickness had a statistically significant effect on schoolchildren headache (P = 0.000).Conclusion: Headache is a common health problem among schoolchildren in Mersin, which merits increased attention and detailed multicentre epidemiological and clinical studies.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A model for P300 generation based on responses to near-threshold visual stimuli

Cognitive Brain Research, 1999

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fetal growth restriction due to placental disease

Seminars in Perinatology, 2004

Normal fetal growth depends on the genetically predetermined growth potential and its modulation ... more Normal fetal growth depends on the genetically predetermined growth potential and its modulation by the health of the fetus, placenta and the mother. Fetuses that are small because of intrauterine growth restriction (IUGR) are at higher risk for poor perinatal and long-term outcome than those who are appropriately grown. Of the many potential underlying processes that may result in IUGR, placental disease is clinically the most relevant. Fetal cardiovascular and behavioral responses to placental insufficiency and the metabolic status are interrelated. The concurrent evaluation of fetal biometry, amniotic fluid volume, heart rate patterns, arterial and venous Doppler, and biophysical variables therefore allow the most comprehensive fetal evaluation in IUGR. In the absence of successful intrauterine therapy, the timing of delivery is perhaps the most critical aspect of the antenatal management. A discussion of the fetal responses to placental insufficiency and a management protocol that accounts for multiple Doppler and biophysical parameters as well as gestational age is provided in this review.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of Poly(ADP-Ribose) Polymerase Inhibition in Bladder Damage Caused by Cyclophosphamide in Rats

It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and ... more It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and peroxynitrite are responsible for cyclophosphamide (CP)-induced cystitis. Since endogenous production of peroxynitrite is known to lead to poly(ADP-ribose) polymerase (PARP) activation, in this study, the aim was to evaluate whether the PARP activation pathway is also included in the pathogenesis of CP-induced bladder ulceration in rats. A total of 48 male albino Wistar rats were divided into 5 groups. Group 1 served as control and was given 2 ml saline; four groups received a single dose of CP (200 mg/kg) with the same time intervals. Group 2 received CP only; Group 3, selective iNOS inhibitor 1400W (20 mg/kg); Group 4, peroxynitrite scavenger ebselen (30 mg/kg); and Group 5, PARP inhibitor 3-aminobenzamide (20 mg/kg). CP injection resulted in severe cystitis with continuous macroscopic hemorrhage, strong edema, inflammation, and ulceration. Moreover, bladder iNOS activation and urine nitrite-nitrate levels were dramatically increased. Histologically, 1400W protected bladder against CP damage and decreased urine nitrite-nitrate levels and bladder iNOS induction. Ebselen has shown similar histologic results with 1400W without changing urinary nitrite-nitrate level and iNOS activity. Furthermore in the 3-aminobenzamide group, beneficial effects had also occurred including decreased ulceration. These results suggest that PARP activation involves pathogenesis of CP-induced bladder ulceration. Furthermore, PARP is not only important for ulceration but also for bladder edema, hemorrhage, and inflammation because of broken uroepithelial cellular integrity.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of a Nonionic Surfactant on the Water Retention Properties of Unsaturated Soils

Soil Science Society of America Journal, 2001

Jm 2 while solid-liquid contact angle decreased from 40 to 10. No further changes in interfacial ... more Jm 2 while solid-liquid contact angle decreased from 40 to 10. No further changes in interfacial properties or soil water characteris- results in a lowering of both the surface tension of water tics were observed at surfactant concentrations above the CMC. The and the contact angle between the solid and aqueous experimental results were used to develop and evaluate alternative

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Decreased oxidation susceptibility of plasma low density lipoproteins in patients with Gilbert's syndrome

Journal of Gastroenterology and Hepatology, 2008

Background and Aim: The association of hyperbilirubinemia in Gilbert's syndrome (GS) with a decr... more Background and Aim: The association of hyperbilirubinemia in Gilbert's syndrome (GS) with a decrease in prevalence of coronary artery disease is a well-known phenomenon. In this study, the state of low-density lipoprotein (LDL) oxidation which has been postulated to be a significant determinant at the etiopathogenesis of atherosclerotic disorders was investigated among individuals with GS.Methods: For this purpose, serum cholesterol, LDL cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, apolipoprotein A and B, bilirubins, thiobarbituric acid-reactive substances, and the sensitivity of LDL oxidation levels, as well as serum alanine aminotransferase, aspartate aminotranserfase, gamma glutamil transferase, and alkaline phosphatase activities, were determined in 17 patients with Gilbert's syndrome and 15 healthy adults.Results: There was no significant difference between the groups except the indirect bilirubin parameter (P < 0.001). In comparison with the healthy individuals, LDL oxidation levels between 75 and 120 min were significantly lower (P < 0.005) along with prolonged lag-phase in GS patients, indicating a delay in oxidation susceptibility.Conclusion: It is suggested that the chronic hyperbilirubinemia leading to a lag-phase prolongation in LDL oxidation and a decrease in LDL oxidation may be reason for the low percentage of coronary artery disease.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Infrared and Raman study of some isonicotinic acid metal(II) halide and tetracyanonickelate complexes

Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Ameliorative Effects of Proanthocyanidin on Renal Ischemia/Reperfusion Injury

Renal Failure, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Biomechanical evaluation of a fiber-reinforced composite prosthesis supported by implants with and without a microthread collar design

Journal of Dental Sciences, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of different fixation methods following sagittal split ramus osteotomies using three-dimensional finite elements analysis

International Journal of Oral and Maxillofacial Surgery, 2005

The purpose of this study was to evaluate the mechanical behavior of different fixation methods u... more The purpose of this study was to evaluate the mechanical behavior of different fixation methods used in bilateral sagittal split ramus osteotomy (BSSRO). Part 1 comprises of the results of the analysis for mandibular advancement, four different fixation configurations of six hole fragmentation mini plates with monocortical screws and lag screws and posterior loading conditions in the molar and premolar region. The finite element analysis method (FEA) appears suitable for simulating complex mechanical stress situations in the maxillofacial region. The mechanical behavior of selected lag screws with linear or triangular configuration and double parallel or single oblique six hole mini plates with monocortical screws were compared by FEA after 5 mm BSSRO advancement procedure. Four separate three-dimensional finite element models of the mandible were created to simulate the BSSRO and corresponding fixation methods. These models consisted of 122,717 elements and 25,048 nodes. The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer&#39;s information. 500 N posterior occlusal loads were simulated on the distal segments. The commercial finite element solver MSC Marc software was utilized to calculate the stress fields on both the segments and fixative appliances. It was concluded that the use of 2.0mm lag screws placed in a triangular configuration following the BSSRO advancement surgery provides sufficient stability with any rotational movement and less stress fields at the osteotomy site, when compared with the other rigid fixation methods used in the current study.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA. Part 1: Advancement surgery

International Journal of Oral and Maxillofacial Surgery, 2008

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA

International Journal of Oral and Maxillofacial Surgery, 2009

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA

International Journal of Oral and Maxillofacial Surgery, 2009

The study aimed to calculate the location and intensity of the maximum stress fields on the fixat... more The study aimed to calculate the location and intensity of the maximum stress fields on the fixation plates and surrounding maxilla following Le Fort I osteotomies after advancement procedures using three-dimensional finite element analysis. The models were generated using skull CT scan data. Le Fort I osteotomy simulations were made and two separate impacted maxillary models were designed. The ADV-2 model has 2 plate fixations bilaterally at the piriform rims, the ADV-4 model has 4 plate fixations at the zygomatic buttresses and piriform rims. The stress fields on bone, plate and screws were computed for each model. Posterior occlusal loads were simulated on one side in the molar-premolar region, in all three directions, reflecting the chewing forces. The increased locations of highest Von Mises stresses on the plates and highest maximum principle stresses on the bones were determined in ADV-2 models especially under horizontal and oblique loads when compared with ADV-4 models. Evaluation of the highest Von Mises stress values and maximum principal stress revealed that oblique load in the ADV-2 model received the highest values. 4-plate fixation following Le Fort I advancement surgery exerts less stress on the maxillary bones and fixation materials than 2-plate fixation.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Three-dimensional finite element analysis used to compare methods of fixation after sagittal split ramus osteotomy: setback surgery-posterior loading

British Journal of Oral & Maxillofacial Surgery, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of prosthesis type and material on the stress distribution in bone around implants: A 3-dimensional finite element analysis

Journal of Dental Sciences, 2011

The design and materials of a prosthesis affect the loading of dental implants and deformation of... more The design and materials of a prosthesis affect the loading of dental implants and deformation of the bone. The aim of the study was to evaluate the effects of prosthesis design and materials on the stress distribution of implant-supported prostheses.A 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the bone. Three different models were designed as follows: a 3-unit implant-supported fixed partial denture (FPD) composed of a metal framework and porcelain veneer with (M2) or without a cantilevered extension (M1) and an FPD composed of a fiber-reinforced composite (FRC) framework and a particulate composite veneer without a cantilevered extension (M3). In separate load cases, 300-N vertical, 150-N oblique, and 60-N horizontal forces were applied to the prostheses in the models. von Mises stress values in the cortical and cancellous bone were calculated.In cortical bone, the highest von Mises stresses were noted in the M2 Model with a vertical load; whereas, higher stresses were observed in the M1 Model with horizontal and oblique loads. The lowest stress values were determined in the M3 Model for all loading conditions. In cancellous bone, decreased stress values were found with all 3 models under the applied loads.Prosthesis design and materials affect the load-transmission mechanism. Although additional experimental and clinical studies are needed, FRC FPDs can be considered a suitable alternative treatment choice for implant-supported prostheses. Within the limitations of the study, the 3-unit FPD supported by 2 implants with a cantilevered extension revealed acceptable stress distributions.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Biomechanical comparison of implant retained fixed partial dentures with fiber reinforced composite versus conventional metal frameworks: A 3D FEA study

Journal of The Mechanical Behavior of Biomedical Materials, 2011

Bookmarks Related papers MentionsView impact