• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.85-91
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• 2012

Purpose: The object of this study was to determine if the low-priced alloy and metal UCLA abutment could be available for manufacturing bar-retained framework of implant prosthesis. Materials and methods: Bar structure was classified into 4 groups, The specimen of group 1 and 2 were based on casting high noble metal alloys and noble metal alloys with gold UCLA abutment. The specimen of group 3 and 4 were based on casting noble metal alloys and base metal alloys with metal UCLA abutment. Cast bar structure was installed in an acrylic resin model and only the screw on the hexed abutment side was tightened to 20 Ncm. On the opposite side, vertical discrepancy was measured with stereo microscope from front, back, and lateral side of the implant-abutment interface. One-way ANOVA was performed to analyze the marginal fit discrepancy. Results: One-way ANOVA test showed significant differences among all groups ($P$<.05) except for Group 1 and 3. Among them, difference between Group 1 and 2 was noticeable. Measured vertical discrepancies were all below $70{\mu}m$ except to Group 2. Conclusion: Base metal alloy and metal UCLA abutment could be used as an alternative to high-priced gold alloy for implant bar-retained framework.

• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.71-77
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• 2020

Purpose: To determine if sparing the interspinous and supraspinous ligaments during posterior decompression for lumbar spinal stenosis is significant in preventing postoperative spinal instability. Materials and Methods: A total of 83 patients who underwent posterior decompression for lumbar spinal stenosis between March 2014 and March 2017 with a minimum one-year follow-up period, were studied retrospectively. The subjects were divided into two groups according to the type of surgery. Fifty-six patients who underwent posterior decompression by the port-hole technique were grouped as A, while 27 patients who underwent posterior decompression by a subtotal laminectomy grouped as B. To evaluate the clinical results, the Oswestry disability index (ODI), visual analogue scale (VAS) for both back pain (VAS-B) and radiating pain (VAS-R), and the walking distance of neurogenic intermittent claudication (NIC) were checked pre- and postoperatively, while simple radiographs of the lateral and flexion-extension view in the standing position were taken preoperatively and then every six months after to measure anteroposterior slippage (slip percentage), the difference in anteroposterior slippage between flexion and extension (dynamic slip percentage), angular displacement, and the difference in angular displacement between flexion and extension (dynamic angular displacement) to evaluate the radiological results. Results: The ODI (from 28.1 to 12.8 in group A, from 27.3 to 12.3 in group B), VAS-B (from 7.0 to 2.6 in group A, from 7.7 to 3.2 in group B), VAS-R (from 8.5 to 2.8 in group A, from 8.7 to 2.9 in group B), and walking distance of NIC (from 118.4 m to 1,496.2 m in group A, from 127.6 m to 1,481.6 m in group B) were improved in both groups. On the other hand, while the other radiologic results showed no differences, the dynamic angular displacement between both groups showed a significant difference postoperatively (group A from 6.2° to 6.7°, group B from 6.5° to 8.4°, p-value=0.019). Conclusion: Removal of the posterior ligaments, including the interspinous and supraspinous ligaments, during posterior decompression of lumbar spinal stenosis can cause a postoperative increase in dynamic angular displacement, which can be prevented by the port-hole technique, which spares these posterior ligaments.