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PubMed1988

Mandibular reconstruction with the titanium hollow screw reconstruction plate (THORP) system: evaluation of 62 cases.

The titanium hollow screw reconstruction plate (THORP) system for reconstruction of lower jaw defects provides a functional stable fixation and is used as a long-term or permanent implant in tumor surgery and in traumatology. The rigid fixation of the head of the screw to the plate, avoiding unphysiologic loads to the bone underneath the plate, and the titanium plasma-coated perforated hollow screws, enabling the development of direct bone-titanium contact as well as the ingrowth of bone into the lumen and perforations, are the major advantages of this system compared to conventional systems. The different surgical methods, such as preservation of the condylar process with only two screws, intraoperative freely adjustable condylar prosthesis, lingual application of the plate, and primary bone transplantation, are described. The evaluation of 62 patients reconstructed with the THORP system between 1981 and 1986 revealed no plate loosening, even in irradiated bone, and showed satisfactory aesthetic and functional results.

Adult↗
PubMed1997

Threaded titanium cages for lumbar interbody fusions.

STUDY DESIGN: This study evaluated safety, fusion success rate, and clinical outcome of a new lumbar interbody hollow, threaded titanium fusion cage in a multicenter, prospective 236-case program adhering to a United States Food and Drug Administration Investigational Device Exemption controlled protocol. OBJECTIVES: The results were evaluated to demonstrate the safety and effectiveness of this new method to achieve solid lumbar interbody fusions. SUMMARY OF BACKGROUND DATA: Interbody fusions have certain distinct mechanical advantages over lateral or posterolateral ones. Autologous, cancellous bone is the preferred graft material, but is too soft to maintain the space during fusion without mechanical support. Various methods have been used in the past to maintain the graft integrity during fusion development. METHODS: An initial pilot study began on 10 patients (followed for 84 months, average 80 months). Two years after that investigation started, the multicenter United States Food and Drug Administration Investigational Device Exemption study began, with cases followed for 28-46 months (average, 32). Ninety-six percent of the investigational Device Exemption study cases had severe, disabling back pain; in addition, 74% had major annular degeneration; 57% had herniations; 21% had osteophytes; and 43% had disc height reduced by greater than 10%. Forty-five percent of cases had previous spinal surgeries, and none were posterior lumbar interbody fusions. Titanium fusion cage pairs were screwed into bored and threaded, parallel intradiscal holes, and 3-8 ml autologous cancellous bone was packed inside each. Fusion success was judged by absence of motion on flexion-extension radiographs, absence of bone halo around the implants, and maintenance of visible bone inside the cages on Ferguson view radiographs. RESULTS: Segments fused rapidly; the pilot study cases fused at 10 (91%) of 11 levels, with a reported 80% average clinical improvement. Ninety-six percent of the 208 2-year follow-up Investigational Device Exemption cases had fusion, and the Prolo socioeconomic/ functional improvement scale showed: 40% excellent, 25% good, 21% fair, and 14% poor results. Less than 1% of Investigational Device Exemption cases had complications that persisted beyond the average 5 days of hospitalization, and none were serious. CONCLUSIONS: The Ray titanium fusion cage (Surgical Dynamics, Norwalk, CT) implant method has been found to be an effective, rapid, safe procedure for lumbar spine fusions, demonstrating a high fusion rate and clinical success with rare, serious, or permanent complications.

Adolescent↗
PubMed2001

An experimental study on the interface strength between titanium mesh cage and vertebra in reference to vertebral bone mineral density.

STUDY DESIGN: Using human cadaver spines, the authors investigated mechanical properties of the interface between titanium mesh cage and vertebra in respect to vertebral bone mineral density. OBJECTIVES: The objective of this study is to examine the effects of the size of the mesh cage and an internal end ring system on interface mechanical properties in reference to vertebral bone mineral density. SUMMARY OF BACKGROUND DATA: A titanium mesh cage has recently been developed for anterior spinal reconstruction. The cage provides immediate postoperative stability and facilitates bony union with cancellous bone packed in the cage itself. Mechanical properties of the interface between the cage and vertebra, however, are yet to be clarified in osteoporotic spine. METHODS: Twenty-five lumbar vertebrae harvested from embalmed human cadavers (n = 20) were used. The vertebrae were divided into four experimental groups according to the applied cage conditions: Phi25 mm cage without internal end ring (L-), Phi19 mm cage without internal end ring (S-), Phi25 mm cage with internal end ring (L+), and Phi19 mm cage with internal end ring (S+). Bone mineral density of whole vertebral body was measured by dual energy radiograph absorptiometer (DXA). Peripheral quantitative computed tomography was used to determine local bone mineral density of subchondral cancellous bone of vertebral body. Each cage was compressed on vertebral endplate via a specially designed device connected to a material testing machine. Maximum load and stiffness of the interface between the cage and vertebra were measured from load-deformation data in quasi-static compression loading with a loading rate of 0.5 mm/min. Relationships between the mechanical properties and vertebral bone mineral densities were evaluated. In 11 specimens acoustic emission during compression loading was measured and simultaneously recorded in load-deformation data. After the mechanical test microradiograms of midsagittal sections of the vertebrae were taken to observe failure patterns of endplate or trabecular bone. RESULTS: Vertebrae compressed with large cages (group: L- or L+) showed greater maximum load than those compressed with small cages (group: S- or S+). The internal end ring contributed to higher maximumload. The size of the cage or the internal end ring, however, did not have any effect on stiffness. Maximum load and stiffness were positively correlated with whole vertebral bone mineral density measured by dual energy radiograph absorptiometer or local cancellous bone mineral density of subchondral bone measured by peripheral quantitative computed tomography. Correlation coefficient and P value were more significant in the association of the mechanical properties and subchondral bone mineral density measured by peripheral quantitative computed tomography than in the association of the parameters and whole vertebral bone mineral density measured by DXA. A load-deformation curve with an acoustic emission event count rate showed that significant acoustic emission signals were generated around maximum load. On microradiographic study most vertebrae compressed with the cage showed encroachment of the cage spikes into the endplate or trabecular structure, preserving structures of the most central portion of the vertebrae. CONCLUSION: A titanium mesh cage with larger diameter and/or augmentation of internal end ring produces a significant increase of the interface strength between the cage and the vertebra. A positive correlation between the interface strength and vertebral bone mineral density suggests that vertebral bone mineral density is an important parameter for successful spinal reconstruction, and also implies that in severe osteoporotic spine the stability of the cage is declined, and other instrumentation should be combined.

Aged↗
PubMed1999

Osseointegration of titanium metal implants in erbium-YAG laser-prepared bone.

Titanium screws were implanted in rat calvarial defects of identical size using either a laser or bur. The aims of this study were to determine whether the screws were able to osseointegrate in a laser-prepared bone defect and to compare the pattern of bone healing around these screws. The optimal laser settings to produce a 0.7-mm-diameter hole in the rat calvaria were determined. A 0.7-mm-diameter hole was prepared on the left calvaria with the erbium-YAG laser to receive a 1-mm-diameter self-threading titanium screw. Each animal also received a 0.7-mm-diameter hole prepared on the right calvaria with a conventional metal bur, and a 1-mm-diameter self-threading screw implant was placed. Rats were killed humanely either 3 weeks or 3 months after surgery, and the skulls were processed in paraffin wax for histological analysis. Laser-prepared defects: At 3 weeks, the screw was surrounded by vital woven bone. The dura mater was perforated, and cystic change was present in the underlying brain tissue. There was active bone formation adjacent to the screw surface, deposited on a thin zone of necrotic bone. At 3 months, the screws were osseointegrated, and the brain tissue was healed by gliosis. Bur-prepared defects: At 3 weeks, there was extensive remodeling around the prepared defect. The dura mater was intact, and there was no damage to the underlying brain. At 3 months, the screws were successfully osseointegrated with bone adjacent to the screw. Osseointegration of titanium screws can be achieved using an erbium-YAG laser to prepare the implant bed.

Animals↗
PubMed2002

Nicotine and bone density around titanium implants: a histometric study in rabbits.

This study investigated the influence of nicotine on bone density around titanium implants inserted in rabbits. Thirty-two New Zealand rabbits were included. After anesthesia, the tibiae surfaces were exposed and two screw-shaped, commercially available, pure titanium implants of 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. A total of 128 implants were inserted: 64 blasted with Al2O3 particles (group 1) and 64 with a machined surface finish (group 2). The animals were randomly assigned to one of four treatment subgroups, and daily subcutaneous injections of nicotine were administered. After 42 days, the animals were killed and undecalcified sections were prepared. The bone density was measured in the cortical passage of the implant. Statistical analysis (two-way analysis of variance) revealed no significant difference neither regarding the effect of nicotine nor the effect of surface design on bone density around the implants (P > 0.05). Within the limits of the present study, it can be assumed that daily nicotine administration may not statistically influence bone density around titanium implants.

Aluminum Oxide↗
PubMed2003

Pitfalls of anterior cervical fusion using titanium mesh and local autograft.

Cervical fusion cages have been developed to provide an anterior structural support without harvesting tricortical iliac bone. Limited numbers of investigations have focused on pitfalls of anterior cervical fusion using cage implants. The objective of this study is to report clinical results and implant-related complications in anterior cervical fusion using titanium mesh and anterior plating. Twenty-four cases with anterior cervical fusion using a titanium mesh with local autograft and anterior plating were reviewed. One-level fusion was performed in 7 cases, and 17 patients underwent two-level fusion with corpectomy. The mean follow-up period was 27 months. Radiographic assessment included sagittal alignment, fusion status, and complications related to cage implants. Iliac bone graft harvesting was obviated in all the patients, whereas 15 patients required concomitant use of ceramic bone substitute. Sagittal alignment of the operative level was lordotic in 19 cases (79%) and neutral in 5 cases (21%) at the final follow-up. No late kyphotic collapse was observed. Twenty-three cases (96%) achieved a solid fusion, whereas the time to fusion was averaged 6.2 months. Cage subsidence frequently occurred in 42% of upper vertebrae and 50% of lower vertebrae. The use of titanium mesh and local autograft for anterior cervical fusion obviated the need for harvesting iliac bone block and provided structural anterior column support. However, it required a longer period to achieve a solid fusion when compared with tricortical iliac autograft. Cage subsidence was frequently observed in the early postoperative period.

Adult↗
PubMed2001

Comparative electron microscopic study of the surface structure of gold, Teflon, and titanium stapes prostheses.

HYPOTHESIS: The goal of this study was to compare stapes prostheses of different materials with respect to their surface structures and to discuss their suitability for their use in stapes surgery. BACKGROUND: The surface condition of a stapes prosthesis plays an important role in relation to the type of membrane that forms between the stapes piston and the bony edge of the stapedotomy opening. The quality of this membrane in thickness and mobility is one of the determinants for postoperative hearing improvement. METHODS: The surface conditions of gold, Teflon/steel, Teflon/platinum, and titanium stapes prostheses were examined with a scanning electron microscope. The loop, shaft, and end of each prosthesis were studied. RESULTS: The gold piston was the smoothest of the four pistons examined. When it was cut with a scalpel, a very smooth surface was achieved at the end area. The Teflon piston had the roughest surface. However, when it was cut, a smooth surface with a parallel arrangement of fibers resulted. Its steel loop was the smoothest, followed by gold and platinum. The titanium shaft had a scaly surface, which remained when the end of the shaft was shortened. CONCLUSION: Because a certain roughness of the piston surface is necessary for the development of a stable membrane between the piston and the edge of the stapedotomy opening, the titanium prosthesis is considered to be the most suitable for stapes surgery of the three pistons examined.

Gold↗
PubMed2002

Preliminary ossiculoplasty results using the Kurz titanium prostheses.

OBJECTIVE: Limitations in biocompatibility and hearing improvement with ossicular chain reconstruction prostheses are addressed with new, lightweight titanium prostheses designed to maximize visualization of the capitulum and footplate regions. The effectiveness of these new prostheses is being tested in a prospective multicenter study. STUDY DESIGN: Prospective case series. SETTING: Multicenter (8 sites), primarily tertiary private practice or academic otologic clinics. PATIENTS: A convenience sample of 31 patients undergoing ossiculoplasty, with 16 partial ossicular chain reconstructions using the Bell prosthesis and 15 total reconstructions using the Aerial prosthesis. INTERVENTION: Ossiculoplasty using new Kurz titanium prostheses. Cartilage was interposed between the tympanic membrane and the prosthesis. MAIN OUTCOME MEASURES: Air-bone gap for pure tone average and 3,000 and 4,000 Hz, assessed preoperatively and 3 months, 6 months, and 12 months postoperatively; percent of patients obtaining an air-bone gap of </=20 dB; high-frequency average (1,000, 2,000, and 4,000 Hz) to evaluate sensorineural hearing loss; and extrusion rate. RESULTS: A postoperative air-bone gap of </=20 dB was obtained in 81% of Bell prosthesis patients and 67% of Aerial prosthesis patients at 3 months. The results were stable to improved for later time intervals. High-frequency gaps were similar to the pure tone average gap. To date, there have been no instances of extrusion, and all the surgeons found the prostheses easy to use and thought that the design characteristics facilitated accurate placement. CONCLUSIONS: Initial evaluation of the Kurz titanium prostheses produced low extrusion rates (none to date) with excellent hearing results, including good high-frequency conduction. Good visualization and accurate placement were easy to achieve. Further studies are needed to confirm long-term efficacy.

Audiometry, Pure-Tone↗
PubMed2002

Craniofacial titanium implants and chronic pain: histologic findings.

OBJECTIVE: To determine whether histologic features or histomorphometric outcomes of retrieved craniofacial percutaneous titanium implants could be found that could be related to chronic pain at the implant site in the temporal bone. STUDY DESIGN: Histologic investigation and histomorphometric measurements of seven retrieved titanium implants with surrounding bone tissue. SETTING: Tertiairy referral center. PATIENTS AND METHODS: Four patients who had previously received percutaneous titanium implants for auricular prostheses (1 patient) and a bone anchored hearing aid (three patients) had chronic pain at the implant site despite conservative treatment. The implants were retrieved, sectioned, and ground for qualitative light microscopic inspection and quantitative measurement of the bone-to-metal contact and bone area. RESULTS: Qualitative inspection of the sections of the implants demonstrated soft tissue zones at the interface, especially under the flange. Inflammatory cells were seen in the interface in all seven implants. In the implants with good bone-to-metal contact, the percentage of bone-to-metal contact rose with time. In the two implants with poor bone-to-metal contact, the soft tissue zones were more extensive, and slightly more skin reactions were observed than in the other implants while still in situ. CONCLUSION: A clear explanation for the chronic pain is not at hand. The only common histologic findings were the inflammatory cells present in the interface, but with varying density, and the presence of soft tissue zones. A variety of bone-to-metal was found among the retrieved implants.

Adolescent↗
PubMed2006

Titanium mesh for functional reconstruction of the mastoid cortex after mastoidectomy.

OBJECTIVE: To describe a rapid and effective means of reconstructing the mastoid cortex after mastoidectomy for chronic otitis media with and without cholesteatoma. STUDY DESIGN: Retrospective. SETTING: Tertiary referral otology clinic. PATIENTS: Those undergoing tympanoplasty and mastoidectomy for chronic otitis media. INTERVENTION: After tympanoplasty and mastoidectomy, the mastoidectomy defect was reconstructed using titanium mesh with subsequent closure as routine. MAIN OUTCOME MEASURES: Evaluation of soft-tissue ingrowth into the mastoid 12 to 24 months after surgery and clinical evaluation of the postauricular surgical site for accentuation of the postauricular sulcus. RESULTS: In 99 patients, the mastoidectomy defect was reconstructed using titanium mesh. None was found to have pitting of the postauricular sulcus. One patient had partial extrusion of the mesh through the ear canal. No instance of wound infection was observed. Soft-tissue growth into the mastoid cavity was found to be minimized. CONCLUSION: Titanium mesh is a rapid and effective means of minimizing soft-tissue ingrowth into the mastoid and preventing accentuation of the postauricular sulcus after mastoid surgery.

Adolescent↗
PubMed2005

A titanium-encased alumina ceramic bearing for total hip arthroplasty: 3- to 5-year results.

UNLABELLED: We examined whether encasing the alumina ceramic total hip arthroplasty insert in a thin titanium sleeve would reduce significantly or eliminate insert chipping on impaction of the insert into the shell. We also compared results, including observations of osteolysis, of the Trident study group with those of the predecessor alumina bearing couple design to determine clinical improvement and radiographic stability. Beginning in October 1996, 328 alumina ceramic bearings were implanted by six surgeons in 316 patients as a part of a prospective, randomized United States Investigational Device Exemption three-arm study comparing an alumina ceramic bearing with a control bearing of cobalt-chromium on polyethylene. In September 1999, a fourth arm of the study (Trident) was added. The Trident insert was recessed within a thin titanium sleeve. At three to five years followup, osteolysis was found in 0% of the patients with the Trident insert and in 0.5% of the patients with an alumina bearing couple. At a mean followup of 4.2 years (range, 3-5 years) no ceramic chips, fractures, or ceramic bearing failures have occurred. Encasing the alumina ceramic insert in a titanium sleeve seems to have resolved the issue of insert chipping on impaction and supports the continued use of Trident bearings in relatively young patients. LEVEL OF EVIDENCE: Therapeutic study, Level II-1 (prospective comparative study-patients treated one way compared with a group of patients treated in another way at the same institution). See the Guidelines for Authors for a complete description of levels of evidence.

Aluminum Oxide↗
PubMed2006

Treatment of tuberculous spondylitis with anterior stabilization and titanium cage.

UNLABELLED: We retrospectively reviewed 12 patients with spinal tuberculosis of the thoracic and lumbar spine who had radical débridement, anterior decompression, interbody arthrodesis with an anterior interbody titanium cage, and autologous bone grafts, combined with a standardized perioperative antituberculous regimen. Their mean age was 55.1 years and they were observed for a mean of 65.3 months. Indications for surgery included epidural abscess, structural destruction with instability, progressive kyphosis, and/or neurologic deterioration. Kyphotic deformity was corrected from a mean of 24.6 degrees (range, 15 degrees-32 degrees) to a mean of 10 degrees (range, 4 degrees-18 degrees). Tuberculous infection was controlled and bony fusion was achieved in all patients. No recurrence of infection or construct failure was recorded. All patients were safely mobilized within the first postoperative week; back pain fully resolved in eight patients and improved in the remaining four. We conclude that radical débridement followed by anterior stabilization with a titanium cage and bone grafting is a reasonable alternative for tuberculous spondylitis requiring surgical treatment. It enables accurate and lasting deformity correction and provides adequate stability to allow early mobilization. The presence of a titanium cage in an area of mycobacterial infection did not preclude infection control or lead to recurrence. LEVEL OF EVIDENCE: Therapeutic study. Level IV (case series). Please see Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMedDate not supplied

Complications of pediatric femur fractures treated with titanium elastic nails: a comparison of fracture types.

The purpose of this study was to analyze complications seen in children with femur fractures stabilized with titanium elastic nails, comparing their use in stable and unstable fracture patterns. A retrospective review was performed on 39 consecutive children with femur fractures treated with titanium elastic nails. Patients with comminuted or long oblique fractures were classified as having "length-unstable" fractures. Patients were analyzed qualitatively for any predictive factors or treatment variables that increased the risk of complications. There were 24 patients with complications (62%). Eight patients (21%) underwent unplanned surgery prior to complete fracture union. Six of the eight requiring unplanned surgery were treated for "length-unstable" fractures. The complications that required unplanned surgery for either prominent nails or loss of reduction occurred more commonly in unstable non-transverse fracture patterns. The authors conclude that in patients with "length-unstable" femur fractures, consideration should be given to methods of treatment other than titanium flexible intramedullary nails.

Bone Nails↗
PubMedDate not supplied

Biomechanical comparison of flexible stainless steel and titanium nails with external fixation using a femur fracture model.

There are several options available for surgical stabilization of pediatric femoral shaft fractures. The purpose of this study was to compare the stability afforded by Ender stainless steel nails, titanium elastic nails, and one-plane unilateral external fixators for the fixation using a synthetic adolescent midshaft femur fracture model. The anterior-posterior (sagittal plane) bending, lateral (coronal plane) bending, torsional, and axial stiffness values were calculated using 6 different fixation configurations. These included pairs of 3.5-mm-diameter Ender nails with and without distal locking, 3.5- and 4.0-mm-diameter titanium elastic nails as well as single- and double-stacked monolateral external fixators. Eight synthetic femur models, 4 each with simulated transverse and comminuted fracture patterns, were sequentially tested for stability afforded by the various fracture fixation configurations. External fixation exhibited significantly greater control of anterior-posterior angulation compared with all flexible-nailing systems. Although Ender nails were slightly superior to titanium nails in control of sagittal plane angulation, this was not statistically significant. Compared with the external fixation constructs, all 4 flexible nail constructs demonstrated higher torsional stability. For prevention of axial shortening, all fixation methods were similar for the transverse fracture pattern, whereas external fixation was superior to flexible nails in the comminuted fracture model. No significant benefit was demonstrated with double stacking of external fixators. These findings may help guide clinicians choose the optimal fixation method for treatment of pediatric femoral shaft fractures.

Biomechanical Phenomena↗
PubMed2005

Early failures following cervical corpectomy reconstruction with titanium mesh cages and anterior plating.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To evaluate the use of titanium mesh cages in the reconstruction of the cervical spine following corpectomy. SUMMARY OF BACKGROUND DATA: Previous studies have shown high successful fusion rates and low failure rates with this technique. Similar reconstruction techniques using anterior strut bone grafting and anterior plating have shown higher failure rates following multilevel corpectomies. METHODS: A retrospective review was performed of 23 consecutive patients who underwent anterior cervical corpectomy reconstructed with a titanium mesh cage, local autograft, and fixed anterior plating. Medical records and radiographs were reviewed. Average follow-up was 28 months. RESULTS: Seven patients (30%) had reconstruction failures. There was 1 failure (6%) in the 1-level corpectomy group and 6 (75%) in the multilevel corpectomy group. All failures occurred before 12 weeks after surgery. The remaining patients had successful fusion (70%). CONCLUSION: There is a high early failure rate (75%) with the use of a titanium mesh cage and fixed anterior plating for reconstruction of multilevel corpectomies. Posterior fusion and instrumentation should be considered when using this technique for multilevel reconstructions.

Adult↗
PubMed2006

Hydroxyapatite dip coated and uncoated titanium poly-axial pedicle screws: an in vivo bovine model.

STUDY DESIGN: A 1-year-old calf was implanted with titanium pedicle screws either uncoated (n = 7) or coated with hydroxyapatite (n = 7) by the dipping method on the pedicles of vertebrae (t10-l3). OBJECTIVE: To evaluate biomechanical and histomorphologic responses to titanium pedicle screws uncoated and coated with hydroxyapatite. SUMMARY OF BACKGROUND DATA: Failure of fixation caused by loosening of pedicle screws is a problem in spinal surgery. Enhancement of the fixation ability of screws by coating with biocompatible materials may improve prognosis of surgery. METHODS: The calf was euthanized 4 months after implantation for determination of insertion and extraction torques for screws, and histologic and scanning electron microscopic examinations of areas screw embedded. RESULTS: Insertion torques did not differ by the kind of screws (99 +/- 5.7 Ncm). However, extraction torques for screws coated with hydroxyapatite were higher than for screws uncoated (249 vs. 133 Ncm, P < 0.01). As compared with uncoated screws, implanted areas for hydroxyapatite-coated screws were denser, had more cracks, and provided better bonding. Fibrous tissue and new bone formation were observed around the areas of uncoated and hydroxyapatite-coated screws embedded, respectively. CONCLUSIONS: Hydroxyapatite coating of titanium pedicle screws by the dipping method improved fixation and vertebral bone-implant interface, suggesting a decreased risk of a screw-loosening problem.

Animals↗
PubMed2006

Mechanical testing of a smart spinal implant locking mechanism based on nickel-titanium alloy.

STUDY DESIGN: Development and testing of a new spinal implant-locking mechanism based on the special properties of nickel-titanium alloy. OBJECTIVE: To develop a new self-tightening locking mechanism to reduce fretting corrosion at implant junctions. SUMMARY OF BACKGROUND DATA: All current implant locking involves tightening of a nut against the rod and screw head to form a coupling. Particulate debris is generated, and the coupling becomes loose because of wear between the rod and locking mechanism (fretting). To avoid this fretting, a new locking mechanism with an automatic retightening effect based on the superelastic and shape-memory properties of nickel-titanium alloy has been developed. METHOD: The new coupling made of nickel-titanium alloy will tightly lock the rod when temperature increases to 50 degrees C (shape-memory effect). If fretting occurs, the coupling will further tighten itself around the rod (superelastic effect). This new coupling is mechanically tested against 4 current implant couplings. RESULTS: In axial compression, conventional couplings failed between 570 and 740 N, while the new coupling reached 800 N without loosening. In axial rotation, conventional devices failed between 1.8 and 5.3 Nm, while the new coupling reached 6.5 Nm without failure. During testing, the retightening effect could be seen on the force versus displacement plot. CONCLUSIONS: To our knowledge, the self-tightening coupling is a new concept not previously described and is attributable to the superior superelastic effect of the new coupling. This implant coupling has the potential to be used as a very low profile system and also in nonfusion technologies in which demands on the coupling would not higher without the protection of spinal fusion.

Alloys↗
PubMed2005

Shaping ability of RaCe rotary nickel-titanium instruments in simulated root canals.

This study assessed the shaping ability of RaCe rotary nickel-titanium instruments in simulated root canals. Forty simulated root canals consisting of four different shapes were prepared with RaCe rotary nickel-titanium instruments in a crowndown approach. Preoperative images were taken at the outset and postoperative images at various stages of preparation including at the conclusion of the shaping procedure. The combined images enabled assessment of aberrations and resin removal at various positions along the canal length. Overall, mean preparation time to size 40, .02 taper was 1.36 min. Thirty-three canals (83%) maintained the working length, three instruments deformed and no zips, perforations, or ledges were created. Under the conditions of this study RaCe rotary nickel-titanium instruments prepared simulated canals rapidly and successfully, with little change in working length and with few aberrations or instrument deformities.

Dental Alloys↗