Showing 6 results for Zarbakhsh
A Zarbakhsh, A Mazaheri Tehrani, F Shamshirgar, H Khosroshahi,
Volume 3, Issue 3 (8-2018)
Abstract
Background and Aim: The mismatch of the implant-abutment connection can produce instant stress and microleakage which result in mechanical and biological complications. This study aimed to investigate the influence of GapSeal® as a sealing material on the extent of microgap and microleakage at the external hexagon implant platform following cyclic loading.
Materials and Methods: Sixteen implants with an external-hexagon connection (BioHorizons External dental implant) were employed in this in-vitro experimental study. All implant-abutment sets were assigned to two groups and were molded in acrylic resins. GapSeal® was injected into the implants in the experimental (test) group. Then, implant assemblies were tightened with the torque of 30 N/cm, and 1200,000 loading cycles with the force of 100 N and the frequency of 1 Hz were applied. Every sample was immersed in a methylene blue dye to evaluate microleakage. Microgap was measured in six regions randomly using a scanning electron microscope (SEM). The data were entered into SPSS 22 and were analyzed using t-test.
Results: The mean±SD microgap was 0.87±0.35 µm and 3.43±1.61 µm in the test and control groups, respectively. Methylene blue dye was observed in all of the specimens of the control group, while no liquid was seen in the test group. A significant statistical difference was found between the groups regarding the microgap and microleakage (P<0.0001).
Conclusion: Application of GapSeal® reduced the dimension of the microgap and decreased microleakage at the implant-abutment interface.
E Jalalian, Ar Banifatemeh, A Zarbakhsh, A Eskandari Damaneh, E Hashemi, M Shariaty,
Volume 4, Issue 2 (6-2019)
Abstract
Background and Aim: Screw loosening is a common problem with both screw-retained and cemented implant restorations. It is assumed that the abutment diameter affects detorque value and screw loosening. We aimed to determine the effect of two different abutment diameters on detorque value using cyclic loading and thermocycling.
Materials and Methods: This in-vitro experimental study was conducted on sixteen Morse-taper implants (4×10 mm) with two different diameters (3.9 and 5.2 mm) installed with a 25-Ncm torque (n=8). Eight screws from each group (3.9- and 5.2-mm abutments) were maintained for a month in a stable state while the rest of the screws underwent cyclic loading for 10,000 cycles with the frequency of 1 Hz and force of 75 N/cm. Then, thermocycling was done at 5-55°C. Detorque value was determined using the torque meter used for screw tightening. Removal torque values were recorded. Maximum deformation force and fracture resistance were documented. Data were analyzed according to Student's t-test using SPSS 21.0 software.
Results: Detorque values were 18.25±1.91 and 21.13±1.46 Ncm with 3.9- and 5.2-mm abutments, respectively. Detorque loss value was 15.50±5.83% with 5.2-mm abutment and 27±7.63% with 3.9-mm abutment. The mean difference between the two abutment diameters was 2.87±0.85 Ncm. Significant differences were observed on torque loss with 3.9-mm- compared to 5.2-mm-diameter abutments (P=0.004).
Conclusion: The results suggested that torque loss was lower with 5.2-mm abutment diameter.
O Moghaddas, F Sarkarat, A Zarbakhsh, Mm Hoseini, T Bitaraf,
Volume 4, Issue 4 (10-2019)
Abstract
Background and Aim: Reducing the number of pathogenic microorganisms can contribute to reducing the incidence and epidemiology of periodontal diseases. This study aimed to evaluate the clinical effects of Ardox-X active oxygen-containing toothpaste on periodontal indices in patients with at least 1 to 2 implants.
Materials and Methods: In this crossover randomized clinical trial, 30 subjects were randomly divided into two groups (n=15). Oral hygiene instructions were delivered to all subjects before the study. Scaling and root planing (SRP) were performed for all subjects. The subjects were instructed to brush with Oral-B toothpaste and toothbrush twice daily for at least two minutes. All subjects returned 10 days later, and the plaque index (PI) and gingival bleeding index (GBI) were measured. The first group received Ardox-X, and the second group received Oral-B toothpaste. Both groups presented after 7 days, and GBI and PI were measured. SRP was performed again, and the plaque was zeroed. Both groups spent the wash-out period for 10 days. Next, the indices were measured again. The Ardox-X group received Oral-B toothpaste and vice versa. After 7 days, both groups returned, and the indices were measured again. T-test was used for statistical analysis.
Results: No significant difference was observed in the PI changes between the control (0.88±0.22%) and case (0.83±0.22%) groups (P<0.6). The changes in the GBI were significantly different between the control (3.9±3.4%) and case (1.5±2%) groups (P<0.01).
Conclusion: The results of this study showed that Ardox-X toothpaste performs better than the control group (Oral-B) in terms of the GBI.
Sh Naser Mostofy, A Zarbakhsh, Mm Alaei, T Bitaraf,
Volume 5, Issue 3 (8-2020)
Abstract
Background and Aim: Oral bacteria can proliferate in the implant-abutment interface (IAI) and cause inflammation in the peri-implant tissues and adjacent bone. This study aimed to assess the effect of zirconia and titanium abutments on the microleakage of the IAI under oblique cyclic loading conditions.
Materials and Methods: In this in-vitro study, 12 implant-abutment assemblies with zirconia and titanium abutments, in two groups of six, were vertically mounted inside resin blocks modified with autopolymerizing polyester base. The specimens were subjected to 75N oblique cyclic loading at an angle of 30±2° to the longitudinal axis of the implant at a frequency of 1 Hz at 500,000 cycles, which is equivalent to 20 months of human masticatory force. Fuchsine solution was used to evaluate the microleakage. To examine the penetration of fuchsine into the IAI, the fixtures were cut from the middle using a cutting machine. Then, the amount of fuchsine penetration in each of the samples was measured with a stereomicroscope at ×75 magnification at three points in each semicircle (cut implant), and the average of these six points was recorded as microleakage (µm). T-test was used to compare the microleakage after load with the significance level set at 0.05.
Results: The microleakage rate after cyclic loading was 66.08±11.66 µm in zirconia abutments and 39.17±10.65 µm in titanium abutments, which was significantly higher with zirconia abutments (P=0.002).
Conclusion: Microleakage after oblique cyclic loading varies depending on the type of abutment. Titanium abutments showed significantly less microleakage than zirconia abutments.
N Naseri, A Babasafari, E Jalalian, A Mazaheri, A Zarbakhsh,
Volume 6, Issue 4 (9-2021)
Abstract
Background and Aim: This study assessed the effects of cyclic loading on screw loosening, vertical misfit, and microleakage at the fixture-angulated abutment interface.
Materials and Methods: This in vitro study evaluated 12 implants in two groups (n=6). The implants were mounted in self-cure acrylic resin. The abutment screw was torqued to 30 N/cm by a digital torque-meter and re-torqued after 5 min. Six points at the fixture-abutment interface were inspected under a stereomicroscope (x75 magnification), and the distance between the two reference points was measured. Six implant-abutment assemblies then underwent cyclic loading (75 N, 1 Hz, 500,000 cycles) while the remaining six (control group) were stored at room temperature. The distance was measured again at the same 6 points after cyclic loading. Vertical misfit was calculated by subtracting the before and after values. The torque loss was measured by a digital torque-meter. The assemblies were then immersed in fuchsine and incubated at 37°C for 24 h. Next, the abutment was unscrewed and the fixtures were cut in half. The penetration depth of fuchsine was measured at 3 points of each fixture half under a stereomicroscope at x75 magnification, and the mean of the six measurements (entire fixture) was reported as the microleakage score of each sample. Data were analyzed using t-test.
Results: Cyclic loading significantly increased the misfit (P=0.001) and microleakage (P=0.01), and decreased the detorque value (P=0.04). No case of screw loosening was noted in any group.
Conclusion: Cyclic loading significantly increases the vertical misfit, microleakage, and torque loss.
Arezu Babasafari, Ezatollah Jalalian, Arash Zarbakhsh, Abdolkarim Rostamian, Shaghayegh Golalipour, Sotoudeh Khorshidi,
Volume 8, Issue 3 (8-2023)
Abstract
Background and Aim: This study aimed to assess the effect of horizontal cantilever on microgap and microleakage at the implant-straight abutment interface in cement-retained crowns.
Materials and Methods: In this experimental study, 12 implant-abutment assemblies and 12 cement-retained crowns were evaluated. The implant fixtures were bone-level, and had 10 mm length and 4 mm diameter. Straight titanium abutments had 7 mm length, 4 mm diameter, and 1 mm gingival height with Morse-Taper connection. Two groups were evaluated: 6 cement-retained crowns with a horizontal cantilever (test group) and 6 cement-retained crows without a horizontal cantilever (case group). The assemblies underwent load cycling in a chewing simulator. Cyclic load (75 N) with 1 Hz frequency was applied along the longitudinal axis of each specimen to the triangular ridge between the mesiobuccal and mesiolingual cusps of the crown. The amount of microgap before and after cyclic loading, and the microleakage score after immersion in fuchsine were evaluated under a light microscope. Data were compared by t-test (alpha=0.05).
Results: The change in microgap after cyclic loading compared with before was not significant in the control group (P=0.724). However, in the case group, the amount of microgap significantly increased after cyclic loading compared with before (P=0.000). Microleakage in the case group was significantly greater than that in the control group (P=0.019).
Conclusion: Horizontal cantilever caused horizontal microgap and increased the microleakage at the implant-straight abutment interface. |
