• The Journal of Advanced Prosthodontics
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• v.10 no.6
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• pp.415-421
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• 2018

PURPOSE. This study investigated the effects of abutment screw lengths on screw loosening and removal torque in external connection implants after oblique cyclic loading. MATERIALS AND METHODS. External connection implants were secured with abutment screws to straight abutments. The abutment-implant assemblies were classified into seven groups based on the abutment screw length, with each group consisting of five assemblies. A cyclic load of 300 N was applied at a $30^{\circ}$ angle to the loading axis until one million cycles were achieved. Removal torque values (RTVs) before and after loading, and RTV differences were evaluated. The measured values were analyzed using repeated measures of analysis of variance with the Student-Newman-Keuls multiple comparisons. RESULTS. All assemblies survived the oblique cyclic loading test without screw loosening. There was a significant decrease in the RTVs throughout the observed abutment screw lengths when the abutment-implant assemblies were loaded repeatedly (P<.001). However, the abutment screw length did not show significant difference on the RTVs before and after the experiment when the abutment screw length ranged from 1.4 to 3.8 mm (P=.647). CONCLUSION. Within the limit of this experiment, our results indicate that the abutment screw length did not significantly affect RTV differences after oblique cyclic loading when a minimum length of 1.4 mm (3.5 threads) was engaged. These findings suggest that short abutment screws may yield stable clinical outcomes comparable to long screws in terms of load resistance.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.432-442
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• 2006

Statement of problem: One of common problems associated with dental implant is the loosening of abutment screws that retain the implants. Purpose : This study was performed to investigate the influence of abutment screw length and repeated tightening on screw loosening in dental implant. Material and method: Forty nine Hexplants (13mm length, 4.3mm diameter, Ti grade IV, Warantec. Co. Ltd. Seongnam, Korea) and cementation type abutments(straight abutment) and abutment screws (0.4mm/pitch) were divided into 7 groups, depending on abutment screw length. Each implant and abutment was tightened to 30Ncm by torque controller(MGT50, MARK-10 Inc., USA) and the removal torque values were measured during 10 consecutive closure/opening trials. Results and Conclusion: The results of comparing the removal torque value are as follows : 1. There is no significant difference in the removal torque value between groups in 10 consecutive closure/opening trials (p = 0.97). 2. If the fractured abutment screw is engaged in longer than 2.425 thread length, there is no significant difference in the preload between the fractured abutment screw and the new abutment screw when both are equally tightened to 30 Ncm. 3. The removal torque value in the 1st trial(24.510 Ncm) was lower than that in the 2nd, 3rd, 4th, 5th, 6th, 7th trials and the removal torque value in the 2nd trials(25.551 Ncm) was maximum and was decreased in 1311owing trials. The removal torque value in the 1st trial was significantly lower than that in the 2nd, 3rd, 4th trials and was significantly higher than that in the 8th, 9th, l0th trials(p<0.05). 4. In the 2nd, 3rd, 4th, 5th, 6th, 7th trials, the abutment screw was mainly influenced by settling effect and the higher preload was obtained In the 8th, 9th, l0th trials, the abutment screw was mainly influenced by adhesive wear and the progressively lower preload was obtained.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.201-210
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• 2017

This study was conducted to estimate the removal efficiency of algae by a mechanical Screw Brush Cone Filter in a lake. The device used a stainless steel cone-shaped filter with a screw brush. The ability of the developed device to remove algae larger than $20{\mu}m$ in Lake ChaSa, Gwangyang city was tested from August to September 2014. The results show that the removal rates for chlorophyll-a, suspended solids and volatile suspended solids were 44-87%(mean 61%), 35-54%(mean 40%), and 37-46%(mean 43%), respectively. This study also discusses equipment and device operation costs and device application problems, and suggests in situ. solutions to these problems.

• Journal of Korean Foot and Ankle Society
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• v.19 no.4
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• pp.181-187
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• 2015

Purpose: The purpose of this study is to retrospectively analyze the clinical results of screws and Kirschner wire (K-wire) fixation in patients with fracture dislocation of Lisfranc joint and the consequence of screw breakage. Materials and Methods: Sixty patients underwent Lisfranc joint open reduction and removal of internal fixators from January 2007 to December 2011. Forty-nine cases (81.7%) underwent operations with screw alone, and 11 cases (18.3%) underwent operations with both screws and K-wires. Type of internal fixators, duration of internal fixator removal, breakage of internal fixators and satisfaction with reduction were investigated. Additionally, American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scales were analyzed. Results: The internal fixator was broken in 5 cases (8.3%). The average duration of instrument removal was 154 days in the non-broken screw group and 268.6 days in the broken screw group (p<0.05). The average AOFAS midfoot scale was 77.4 in the non-broken screw group and 74.2 in the broken screw group. The most commonly damaged portion was the first tarsometatarsal (Lisfranc) joint. Conclusion: Treatment with screws and K-wires was effective in patients with fracture dislocation of Lisfranc joint. The appropriate time for screw removal should be considered.

• Journal of Korean Neurosurgical Society
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• v.51 no.4
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• pp.203-207
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• 2012

Objective: The purpose of this prospective study was to evaluate the efficacy and safety of screw fixation without bone fusion for unstable thoracolumbar and lumbar burst fracture. Methods: Nine patients younger than 40 years underwent screw fixation without bone fusion, following postural reduction using a soft roll at the involved vertebra, in cases of burst fracture. Their motor power was intact in spite of severe canal compromise. The surgical procedure included postural reduction for 3 days and screw fixations at one level above, one level below and at the fractured level itself. The patients underwent removal of implants 12 months after the initial operation, due to possibility of implant failure. Imaging and clinical findings, including canal encroachment, vertebral height, clinical outcome, and complications were analyzed. Results: Prior to surgery, the mean pain score (visual analogue scale) was 8.2, which decreased to 2.2 at 12 months after screw fixation. None of the patients complained of worsening of pain during 6 months after implant removal. All patients were graded as having excellent or good outcomes at 6 months after implant removal. The proportion of canal compromise at the fractured level improved from 55% to 35% at 12 months after surgery. The mean preoperative vertebral height loss was 45.3%, which improved to 20.6% at 6 months after implant removal. There were no neurological deficits related to neural injury. The improved vertebral height and canal compromise were maintained at 6 months after implant removal. Conclusion: Short segment pedicle screw fixation, including fractured level itself, without bone fusion following postural reduction can be an effective and safe operative technique in the management of selected young patients suffering from unstable burst fracture.

• Journal of Trauma and Injury
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• v.36 no.3
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• pp.265-268
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• 2023

Ankle fractures with syndesmotic injuries often require fixation, where metal screw fixation is a popular method. However, as the patient begins weight-bearing, most syndesmotic screws tend to loosen or break, and removal of such screws has been challenging for the surgeons, as the available techniques require predrilling or trephination and are associated with risks of bone damage. This study presents a case with technical tip for the removal of broken tricortical-fixed non-cannulated syndesmotic screws. It implements the generation of a small cortical window in the medial distal tibia and the use of pliers to engage the screw tip and remove through the medial side. The technique presented in the current study overcomes these limitations and facilitates minimal bone damage and reduced exposure to radiation.

• Journal of Veterinary Clinics
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• v.39 no.1
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• pp.28-31
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• 2022

A 5-week old Thoroughbred foal was presented with severe left carpal valgus. Radiographs of the dorsopalmar projections confirmed the deviation was 14 degrees. Surgery using a single-position screw traversing the physis of the distal radius was performed. The limb was almost straight (2 degrees) 3 weeks after surgery. Visual/radiograph follow-up 7 months after screw removal revealed no over-correction after removal of the screw. Transphyseal bridging using a single-position screw without lateral periosteal transection of distal radius was successful for the correction of foals with this condition.

• The Journal of Advanced Prosthodontics
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• v.5 no.1
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• pp.21-28
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• 2013

PURPOSE. This study examined the effects of the abutment types and dynamic loading on the stability of implant prostheses with three types of implant abutments prepared using different fabrication methods by measuring removal torque both before and after dynamic loading. MATERIALS AND METHODS. Three groups of abutments were produced using different types of fabrication methods; stock abutment, gold cast abutment, and CAD/CAM custom abutment. A customized jig was fabricated to apply the load at $30^{\circ}$ to the long axis. The implant fixtures were fixed to the jig, and connected to the abutments with a 30 Ncm tightening torque. A sine curved dynamic load was applied for $10^5$ cycles between 25 and 250 N at 14 Hz. Removal torque before loading and after loading were evaluated. The SPSS was used for statistical analysis of the results. A Kruskal-Wallis test was performed to compare screw loosening between the abutment systems. A Wilcoxon signed-rank test was performed to compare screw loosening between before and after loading in each group (${\alpha}$=0.05). RESULTS. Removal torque value before loading and after loading was the highest in stock abutment, which was then followed by gold cast abutment and CAD/CAM custom abutment, but there were no significant differences. CONCLUSION. The abutment types did not have a significant influence on short term screw loosening. On the other hand, after $10^5$ cycles dynamic loading, CAD/CAM custom abutment affected the initial screw loosening, but stock abutment and gold cast abutment did not.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.4
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• pp.260-266
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• 2012

Purpose: The purpose of this study is to identify the changes of a physiologic nature and the sedative parameters associated with dexmedetomidine and pethidine, in patients undergoing plate and screw removal surgery, after orthognathic surgery. Methods: Twenty-three patients were sedated with dexmedetomidine and pethidine during plate and screw removal, after orthognathic surgery. An initial loading dose of dexmedetomidine ($1.0{\mu}g/kg$ infused over 10 minutes) was followed by a maintenance dose ($1.0{\mu}g/kg/hr$). Systolic blood pressure, diastolic blood pressure, mean arterial pressure, oxygen saturation, and heart rate were monitored. Perioperative amnesia and anxiety were recorded. Results: Significant changes were found in the blood pressure and heart rate (Freidman test, P<0.05), but not in oxygen saturation (Freidman test, P>0.05). Amnesia during local injection was observed in eight patients (34.8%). Compared with the preoperative anxiety score, the intraoperative anxiety score was decreased. Conclusion: In this study, we found cardiovascular and respiratory stability in intravenous sedation using dexmedetomidine with pethidine, in plate and screw removal, after orthognathic surgery. Furthemore, intravenous sedation using dexmedetomidine with pethidine shows adequate analgesic and sedative effects.

• Journal of the Korean Arthroscopy Society
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• v.10 no.2
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• pp.187-191
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• 2006

Few cases have been reported in which the femoral interference screw has migrated into the posterior compartment after an ACL reconstruction. It usually requires removal, because it leads usually to mechanical symptom. However, the arthroscopic removal of a screw is a technically demanding procedure, especially in the case of an intact integrated ACL graft or one that is encapsulated around the screw. We present a case in which a displaced femoral interference screw migrated within the posterior compartment 11 years postoperatively, after the graft had been successfully incorporated at the femoral site and showed good continuity on MRI and arthroscopic examination. Although it is often technically challenging, through the use of a posterior trans-septal portal, we can successfully remove a displaced femoral interference screw even in the most difficult locations in the posterior compartment without damage to ACL graft.