In vivo osteogenic properties of silicon-incorporated titanium dioxide nanotubes on titanium screw surface / 中国组织工程研究

BACKGROUND: At present, titanium and its alloy materials are mostly used in prosthesis and bone implants. These materials have superior mechanical properties and excellent corrosion resistance, but their bioactivity is insufficient, so it is difficult to form a good chemical bond with bone tissue. OBJECTIVE: To prepare titanium dioxide nanotube coating containing silicon on the surface of pure titanium screw and observe its osteogenic properties in vivo. METHODS: Titanium dioxide nanotube layers were prepared on the surface of pure titanium screws by anodic oxidation method (positive control group). Silicon ions were deposited on the surface of titanium nanotube layers by plasma immersion ion implantation and deposition (experimental group). Pure titanium screws were used as negative control group. The morphology of each group was observed by scanning electron microscope. The three kinds of screws were implanted into the femur of SD rats. The femoral specimens were taken out at 2, 4 and 6 weeks after implantation for biomechanical test, and immunofluorescence analysis was performed at 6 weeks after implantation. The animal experiment was approved by the Ethics Committee of Experimental Animal Management and Animal Welfare of Jiangnan University. RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that uniform double-layer nanotube arrays were observed in the experimental group and the positive control group, and there was no significant difference between the two groups. (2) At 2 and 4 weeks after screw implantation, the average peak pullout force of the experimental group was significantly higher than that of the positive control group and the negative control group (P 0.05). (3) Immunofluorescence showed that at 6 weeks after implantation, there was almost no new bone attachment around the screw in the negative control group, and extensive new bone attachment was observed around the screw thread in the experimental group and the positive control group, among which the new bone formation was the most in the experimental group. (4) The results showed that the silicon dioxide titanium nanotube layer could significantly promote the formation of new bone around the pure titanium screw and increase the pullout force of screws.

Complication and its prevention of the treatment with the titanium screw for mandibular fractures / 中国医师进修杂志

Objective To evaluate the reason of the complications after treating by the intermaxillary traction with the titanium screw and put forward the measures of prevention these complications in mandibular fractures.MethodsOne hundred and twenty-six cases with mandibular underwent intermaxillary traction and fixation with tapping titanium screw were observed and counted for their complications in 1-30 days after finishing the operation.Summarized and analyzed the reasons of the complications.ResultsThe rate of complications was 9.52％(12/126),4 cases of titanium screw loosen,2 cases of bad occlusion,1 case of titanium screw fallen off,1 case of titanium screw around infected,1 case of root tip damage,1 case of titanium screw maxillary penetrated into the sinus,1 case of nerve injury,1 case of dental ulcer.Conclusion The intermxillary traction with the titanium screw is simple,safety and healthy method,but the postoperative complications also don't allow to ignore,surgeons should be controlled strictly,standardized operation,try to avoid complications.

Self-designed adjustable titanium screw in treatment of unilateral vocal cord paralysis: An observation of curative effects / 第二军医大学学报

Objective: To observe the curative effects of self-designed adjustable titanium screw in treatment of unilateral vocal cord paralysis in dogs. Methods: We designed and prepared an adjustable titanium screw. The beagle dogs were divided into an experimental group and a control group (n = 3) at random. Animals in the experimental group had their left recurrent laryngeal nerve resected and received implantation of adjustable titanium screw. The left arytenoid cartilage was adjusted to allow the left vocal cord in the middle, so as to achieve glottis closure when making a sound. The dogs in the control group only received recurrent laryngeal nerve resection. Observation with electron fibrolaryngoscope and CT was done immediately, 1, 2, and 4 months after operation: electron fibrolaryngoscope was also used before operation. The curative effects and the prognoses of dogs were observed. Results: Four months after operation electron fibrolaryngoscope found that the adjustable screw in the experimental group could make the left arytenoid cartilage move inwardly, benefiting glottis closure and improving the voice quality. Animals in the control group had their left vocal cord located in the paramedina position, and there was cleft during glottis closure. CT image indicated that the adjustable screw was in a good position, and there was no breaking off. Local slight inflammation was seen in both groups 1, 2, and 4 moths after operation. Tntrinsic laryngeal muscle atrophy aggravated as time passing by. There was no severe inflammation around the implants or implants excretion. Conclusion: Our adjustable screw is easy to perform in surgical treatment of unilateral vocal cord paralysis; it can be adjusted during operation and the outcome can be observed in time. The short-time effect is confirmed and the method is worth popularizing.

Ingestion of orthodontic anchorage screws: An experimental study in dogs

Foreign bodies with a sharp edge which are accidentally swallowed are likely to become lodged in the stomach. An animal study was undertaken to determine the outcome of orthodontic anchorage screw ingestion. The radiographic findings of ten Mongolian dogs that ingested a total of 10 orthodontic anchorage screws and 10 reamers (both a screw and a reamer per dog) were evaluated. The study showed that all orthodontic anchorage screws and reamers reaching the stomach spontaneously passed, with the exception of two reamers. Further investigation of clinical cases might be necessary to determine whether the results of our animal study are in accordance with clinical findings.

Osseointegration with Ceramic Coated Implant / 대한척추외과학회지

PURPOSE: This study was designed to clarify the osseointegration of the titanium screw coated with CMP, in regard to the time schedule, through the characteristic of early osseointegration. MATERIALS AND METHODS: Mechanical, radiological and histomophometric measurements were performed in 28 rabbit tibial proximal metaphyseal cortical bone screws 6, 12, 26 and 52 weeks after surgery for the in vivo comparison of the osseointegration of titanium screws (3.75 mm diameter, 5 mm length) with different surface treatments: CMP coating group, with the sol-gel method (experimental group) and uncoated group (control group). RESULTS: 1. Radiology: There were no differences between the two groups without a radiolucent line or in regard to the time schedule. 2. Histology: There were no differences between the two groups without a fibrous tissue intervening surface or in regard to the time schedule. 3. Torque test: The test results for the CMP coated group were 1.5 times higher than those for the uncoated group, which was statistically meaningful, but there was no difference in regard to the time schedule. CONCLUSION: CMP coating is an option to increase the osseointegration of the titanium screw.

Changes of abutment screw after repeated closing and opening / 대한치과보철학회지

STATEMENT OF PROBLEM: Wear as a result of repeated closing/opening cycles may decrease the friction coefficient of screw head, threads, and other mating components and, consequently, resistance to opening gradually decreases. It may cause screw loosening, which is one of the most common failures in implant prosthesis. PURPOSE: The purpose of this study is to evaluate the changes on the head and thread surface of the abutment screws after repeated closing and opening through the examination of tested screws in SEM(scanning electron microscope). MATERIALS AND METHODS: Five species of abutments were selected (3i-three, Avana- two) respectively by two pieces. The implant fixtures were perpendicularly mounted in liquid unsaturated polyesther(Epovia, Cray Valley Inc.) with dental surveyor. Each abutment was secured to the implant fixture by each abutment screw with recommended torque value using a digital torque controller. The abutment screws were repeatedly tightened and removed 20 times with a digital controller. FESEM (field emission scanning electron microscope, Netherland, Phillips co., model:XL 30 SFEG) was used to observe changes of each part caused by repeatedly closing/opening expeiment. First, the Photomicrographs of pre-test screws provided by each manufacturer were taken. The changes of each screw were investigated after every fifth closing and opening experiment with FESEM. Scaning electron microscope photomicrographs of each screw were taken four times. RESULTS: As the number of closing and opening was increased, the wear or distortion of hexed or squared slot that contacted with the driver tip was more severely progressed. Wear or distortion of hexed slot was more severe than that of squared slot and it was more remarkable in the titanium screw than in the gold screw. All the tested screws showed that the width in the crest of their screw thread decreased gradually as the test was proceeded. CONCLUSIONS: Conclusively, we recommend the clinical use of gold screw, a periodic exchanges of abutment screws and avoiding repeated closing/opening unnecessarily. We also suggest a more careful manipulation of the abutment screw and screw-driver and using of abutment screw with an acute-angled slot design rather than an obtuse-angled one. Finally, it is suggested that the new slot design and the surface treatment for enduring wear or distortion should be devised.

Evaluation of Osseointegration in Titanium Alloy Cortical Screws with the Passage of Time

PURPOSE: To evaluate the osseointegration of titanium alloy cortical screws with the passage of time. MATERIALS AND METHODS: Fifty four titanium alloy cortical screws (24 mm in length, 3.5 mm in diameter) were implanted bilaterally in the tibial diaphysis of adult mongrel male dogs of similar size and weight (30 +/-5 kg). The insertion torques, radiographs, undecalcified histology, histomorphometric analysis and extraction torques were evaluated at 2, 4 and 8 weeks after surgery. RESULTS: The extraction torque at 2 weeks (1.14+/-0.470 cN. m) was significantly lower than the insertion torque (1.76+/-0.609 cN. m) (p=0.0071), the extraction torque at 4 weeks (2.57+/-1.36 cN. m) was slightly improved and the extraction torque at 8 weeks (3.18+/-0.499 cN. m) was significantly higher than insertion torque (p=0.0005). Direct bony contact in the early phase was poor and intervening fibrous tissue was observed at the bone-screw interface. However, the fixation between the bone and the screws improved with time. The percentage of bone-screw contact at 8 weeks (33.1+/-18.5%) was higher than that of 2 weeks (22.4+/-12.9%), but not statistically significant. CONCLUSION: Because of thermal injury or pressure necrosis, the fixation strength of titanium alloy cortical screws at 2 weeks after implantation is significantly lower than that at the insertion time. So, we should keep in mind the initial phase weakness of screw fixation when we allow the patients the range of motion exercise or weight bearing and the improvement of the initial phase fixation is very important in clinical results.

A study on the fit of the implant-abutment-screw interface / 대한치과보철학회지

STATEMENT OF PROBLEM: There have been previous studies about considerable variations in machining accuracy and consistency in the implant-abutment-screw interfaces. PURPOSE: The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combinations on two randomly selected implants from each of four manufactures. MATERIAL AND METHODS: In this study, screws were respectively used to secure a cemented abutment to a hexlock implant fixture; teflon coated titanium alloy screw(Torq-Tite) and titanium alloy screw in Steri-Oss system, gold-plated gold-palladium alloy screw(Gold-Tite) and titanium alloy screw in 3i system, gold screw and titanium screw in AVANA Dental Implant system, and titanium screws in Paragon System. The implants were perpendicularly mounted in polymethyl methacrylate autopolymerizing acrylic resin block(Orthodontic resin, Densply International Inc. USA) by use of dental surveyer. Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10minutes. All samples were cross sectioned with grinder-polisher unit(Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). RESULTS: There were the largest gaps in the neck areas of screws in hexagonal extension implants which were examined in this study. The leading edge of the abutment screw thread (superior surface) was in contact with the implant body thread, and the majority of the contacting surfaces were localized to the middle portion of the mating threads. Considerable variation in the contacting surfaces was noted in the samples evaluated. Amounts of contact in the abutment screw thread were larger for assemblies with Gold-Tite screw, gold alloy screw, Torq-Tite screw than those with titanium screws. The findings of intimate contact between the screw and screw seat were seen in all samples, regardless of manufacturers. However, microgap between the head and lateral neck surface of the screw and the abutment could be dectected in all samples. The findings of intimate contact between the platform of the implant and the bottom of the abutment were consistent in all samples, regardless of manufacturers. However, microgaps between the lateral surface of external hex of the fixture and the abutment could be dectected in all samples. CONCLUSION: Considerable variations in machining accuracy and consistency were noted in the samples and the implant-abutment-screw interfaces were incomplete. From the results of this study, further development of the system will be required, including improvements in pattern design.

A study on surface alteration of implant screws after function / 대한치과보철학회지

STATEMETN OF PROBLEM: Surface alteration of the implant screws after function may be asso-ciated with mechanical failure. Theses metal fatigue appears to be the most common cause of structural failure. PURPOSE: The purpose of this study was to evaluate surface alteration of the implant screws after function through the examination of used and unused implant screws in SEM(scanningelectron microscope). MATERIAL AND METHODS: In this study, abutment screws(Steri-oss, 3i), gold retaining screw(3i) and titanium retaining screw(3i) were retrieved from patients. New, unused abutment and retain-ing screws were prepared for control group. Each of the old, used screws was retrieved with a screwdriver. And retrieved implant complex of Steri-oss system was prepared for this study. Then, SEM investigation and EDS analysis of abutment and retaining screws were per-formed. And SEM investigation of cross-sectioned sample of retrieved implant complex was performed. RESULTS: In the case of new, unused implant screws, as maunfactured circumferential grooves are regularly examined and screw thread are sharply remained. Before ultrasonic cleans-ing of old, used implant screw, a lot of accumulation and corrosion products were existed. After ultrasonic cleansing of old, used implant screws, circumferential grooves as examined before function were randomly deepened and scratches increased. Also, dull screw thread was examined. More surface alterations after function were examined in titanium screw than gold screw. And more surface alteration was examined when retrieved with driver than retrieved without driver. CONCLUSIONS: These surface alteration after function may result in the screw instability. Regularly cleansing and exchange of screws was recommended. We recommend the use of gold screw rather than titanium screw, and careful manipulation of the driver.

Anterior Vaginal Wall Sling Operation with Bone Fixation using Self-made Titanium Screw for Stress Urinary Incontinence Associated with Intrinsic Sphincter Deficiency / 대한비뇨기과학회지

PURPOSE: Anterior vaginal wall sling operation (by Raz`s method )for the treatment of stress urinary incontinence(SUI) associated with intrinsic sphincter dysfunction(ISD) may produce postoperative suprapubic discomfort and suture related problem such as pull-through and loosening. Stabilization of the bladder neck to the pubic bone decreases the tension placed on the anterior rectus fascia and lessens the possibility of suture-related pain and the risk of entrapment of ilioinguinal neve branches. At present, bone anchoring system is available in Korea but its cost sometimes limit the use of the kit. Therfore, we developed self-made titanium screw which is anchored to pubic bone at the time of anterior vaginal wall sling operation and acquired good short-term results. MATERIALS AND METHODS: Total 16 women who had SUI with ISD were treated by in-situ anterior vaginal wall sling using self-made titanium screw anchored to pubic bone to support the bladder neck and midurethra. Postoperative results were analyzed for 16 patients who has been followed up for more than 3 months after surgery. RESULTS: Overall cure rate was 100% at 3 months of follow-up. Complication included anemia in 2 patients, mild dysuria in 2 patients and osteitis pubis in 1 patient. After resting and antibiotic therapy, complications were subsided. CONCLUSIONS: In short term follow-up, anterior vaginal wall sling using self-made titanium screw was shown to be very effective treatment of SUI with ISD with simple technique and had relatively low cost, low complication rates. Long-term followup will be necessary to define the efficacy of this method.

Influence of Type of Screw on the Bacterial Adherence and Infection / 대한정형외과학회잡지

The purpose of the study was to evaluate the effect of commonly used orthopaedic material, stainless steel (SS) screw (2.7xlOmm, Synthes) and titanium (Ti) screw (2.7x10mm, Synthes), on bacterial adherence and infection. The bacteria used for this study was Staphylococcus epidermidis for its ability of adherence. For in vitro assay, screws of each material were placed into test tube containing 107 colony forming unit (CFU) of S. epidermidis in trypticase soy broth for 18 hours. Following incubation, each screws were treated either with trypsin or with an ultrasonic cleaner. For in vivo assay, we inoculated 5x107 CFU of S. epidermidis into the proximal tibial metaphysis of the rabbits, and then inserted Ti screw on the right side and SS screw on the left side. The amount of in vitro adherence of S. epidermidis was greater for SS screw than for Ti screw. Especially following trypsin treatment, SS groups yielded significantly higher bacterial counts than Ti group, respectively (1.4x105 CFU vs 2.8x104 CFU, p<0.05). We found a significantly higher bacterial count after use of SS screw than after Ti screw in rabbits in vivo assay also. Trypsin treatment for identifying biofilm embedded bacteria from implanted metal may be useful in the diagnosis of infection. Ti screw appears to have biocompatibility to inhibit bacterial adherence compared with SS screw in the rabbit tibial model.