• Radiation Oncology Journal
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• v.34 no.4
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• pp.280-289
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• 2016

Purpose: Early hypopharyngeal squamous cell carcinoma (HPSCC) is a rarely diagnosed disease, for which the optimal treatment has not been defined yet. We assessed patterns of failure and outcomes in early HPSCC treated with various therapeutic approaches to identify its optimal treatment. Materials and Methods: Thirty-six patients with stage I (n = 10) and II (n = 26) treated between January 1992 and March 2014 were reviewed. Patients received definitive radiotherapy (RT) (R group, n = 10), surgery only (S group, n = 19), or postoperative RT (PORT group, n = 7). All patients in both the R and PORT groups received elective bilateral neck irradiation. In the S group, 7 patients had ipsilateral and 8 had bilateral dissection, while 4 patients had no elective dissection. Results: At a median follow-up of 48 months, the 5-year locoregional control (LRC) rate was 65%. Six patients had local failure, 1 regional failure (RF), 3 combined locoregional failures, and 2 distant failures. There was no difference in 5-year LRC among the R, S, and PORT groups (p = 0.17). The presence with a pyriform sinus apex extension was a prognosticator related to LRC (p = 0.01) in the multivariate analysis. Patients with a bilaterally treated neck showed a trend toward a lower RF rate (p = 0.08). Conclusion: This study shows that patients with early stage HPSCC involving the pyriform sinus apex might need a tailored approach to improve LRC. Additionally, our study confirms elective neck treatment might have an efficacious role in regional control.

• Journal of Korean Neurosurgical Society
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• v.37 no.6
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• pp.416-421
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• 2005

Objective: Despite general agreement on the goals of surgical treatment in thoracolumbar burst fractures, considerable controversy exists regarding the choice of operative techniques. This study is to evaluate the efficacy of short-segment fixation for thoracolumbar burst fractures after long-term follow-up and to analyze the causes of treatment failures. Methods: 48 out of 60 patients who underwent short-segment fixation for thoracolumbar burst fractures between January 1999 and October 2002 were enrolled in this study. Their neurological status, radiological images, and hospital records were retrospectively reviewed. Simple radiographs were evaluated to calculate kyphotic angles and percentages of anterior body compression (%ABC). Results: The average kyphotic angles were $20.0^{\circ}$ preoperatively, $9.6^{\circ}$ postoperatively, and $13.1^{\circ}$ at the latest follow-up. The average %ABC were 47.3% preoperatively, 31.2% postoperatively, and 33.3% at the latest follow-up. The treatment failure, defined as correction loss by $10^{\circ}$ or more or implant failure, was detected in 6 patients (12.5%). 5 out of 6 patients had implant failures. 2 out of 5 patients were related with osteoporosis, and the other 2 were related with poor compliance of spinal bracing. 3 patients with poor initial postoperative alignment had implant failure. 4 patients with screws only on the adjacent vertebrae and not on the injured vertebra itself showed poor initial and overall correction. Conclusion: With proper patient selection, adequate intraoperative reduction with screw fixation involving the injured vertebra, and strict postoperative spinal bracing, the short-segment fixation is an efficient and safe method in the treatment of thoracolumbar burst fracture.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.590-596
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• 2002

The resin : metal interface is at the basis of most bonding failures in resin-bonded prosthesis. Although debonding has been a problem with adhesive fixed partial dentures, various dentists classify them as long-term restorations. The advantages of resin-bonded fixed partial dentures include minimal tooth reduction and the possibility of rebonding. if resin-bonded protheses can be easily rebounded, it is of clinical importance to know if the lutingagents rebond as well the second time as they did originally. Several retentive systems for resin-to-metal bonding have recommended. Treatments such as electrolytic etching and silicone coating, despite the good result of bond strength, have proved to be time-consuming and technique-sensitive. Therefore a simple and more reliable method is desirable. This study evaluated the effect of metal surface treatments on the rebond strength of panavia 21 cement to a nickel-chromium(Ni-Cr) alloy. The samples were received the following surface treatments : Group No.1 (control or served as the control) treatment with sandblasting with 50um aluminum oxide and ultrasonically cleaned for 10minutes in double-deionized water, Group No.2 were no surface treatments. Group No.3 were treated with metal primer. Group No.4 were treated with sandblasting as previously described, and then metal priming. From the analysis of the results, the following conclusions were drawn. 1. Sandblasting and metal priming appears to be an effective method for treatment of metal after accidental debonding. 2. Group without surface treatment had significantly lower bond strengths compared with other groups. 3. The combination of sandblasting and metal priming may not develop superior bonding strengths compared with other techniques that used the Ni-Cr alloys. 4. Combination of cohesive and adhesive failures were the most common type observed. The results support the use of sandblasting as a viable procedure when rebonding accidentally lost adhesive partial denture. We concluded that sandblasting and metal priming of metal surface before bonding could provide the adequate bond strength during rebonding of resin-bonded fixed partial denture.

• Radiation Oncology Journal
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• v.23 no.3
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• pp.186-193
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• 2005

Purpose: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2l00C over a ten year period were retrospectively analyzed. Materials and Methods: The failures were classified according to the involved functional subunits, with each class rated Into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. Results: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for $20\%$ of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and $83\%$ of the expected values, respectively. The operating efficiency was maintained at $95\%$ or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. Conclusion: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. Wore rigorous equipment maintenance Is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the qualify of patient treatment.

• Radiation Oncology Journal
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• v.29 no.4
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• pp.228-235
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• 2011

Purpose: To evaluate the impact of postoperative radiotherapy (PORT) on patterns of failure and survivals in uterine carcinosarcoma patients treated with radical surgery. Materials and Methods: Between October 1998 and August 2010, 19 patients with stage I-III uterine carcinosarcoma received curative hysterectomy and bilateral salpingo-oophorectomy with or without PORT at Seoul National University Hospital. Their hospital medical records were retrospectively reviewed. PORT and non-PORT groups included 11 and 8 patients, respectively. They were followed for a mean of 22.7 months (range, 7.8 to 126.6 months). Results: At 5 years, the overall survival rates were 51.9% for entire, 61.4% for PORT, and 41.7% for non-PORT groups, respectively. There was no statistical difference between PORT and non-PORT groups with regard to overall survival (p = 0.682). Seven out of 19 (36.8%) patients showed treatment failures, which all happened within 12 months. Although the predominant failures were distant metastasis in PORT group and loco-regional recurrence in non-PORT group, there was no statistically significant difference in locoregional recurrence-free survival (LRRFS) (p = 0.362) or distant metastasis-free survival (DMFS) (p = 0.548). Lymph node metastasis was found to be a significant prognostic factor in predicting poor LRRFS (p = 0.013) and DMFS (p = 0.021), while the International Federation Gynecology and Obstetrics (FIGO) stage (p = 0.043) was associated with LRRFS. Conclusion: Considering that adjuvant radiotherapy after surgical resection was effective to decrease loco-regional recurrence and most treatment failures were distant metastasis, multimodal therapy including surgery, radiotherapy, and chemotherapy might be an optimal treatment for uterine carcinosarcoma patients.

• The Journal of the Korean dental association
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• v.38 no.3 s.370
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• pp.288-292
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• 2000

Perhaps the most frustrating scenario in dentistry lies in the apparently well-instrumented and well-obturated tooth that, becomes symptomatic after treatment of shows a periapical lesion on recall examination. Conventional root canal treatment demands stringent adherence to asepsis, awareness of canal morphology, and mastery of a variety of clinical techniques. But the risk of endodontic failure does not end with canal obturation. The quality of the coronal restoration may have a greater bearing on the ultimate success of a case than the quality of the root canal treatment itself. This review of the endodontic literature will define coronal leakage, describe its influence on endodontic treatment failures, and make specific recommendations on prevention.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.2
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• pp.83-90
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• 2005

Failure cause of the fractured engine parts was analyzed by microstructural observation. These parts were failed far earlier than the expected service life. By the stereoscope and SEM examinations of the fractured surface, the fracture modes have been identified as wear and fatigue failure. From the observation of microstructure and microhardness measurements of the failed gears, the probable cause for failures are internal oxidation during using and retained austenite and carbide networks due to heat-treatment, respectively. These defected structures at near surface contributed to the wear and fatigue failure.

• Proceedings of the KACD Conference
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• 2001.05a
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• pp.257-257
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• 2001

Failures occur in dentistry as a result of manny factors some of which can be controlled by the operator whilst others are unavoidable. The long-term success rate of endodontic treatment has often been thought to be very high although studies reported in the literature do not support this perception. The number of failure can be reduced by adhereing to accepted treatment procedures and by avoiding 'short cut'. Endodontic disaters are usually related to operator errors and they mat have detrimental effects on the outcome of treatment in the long term, eventually becoming catastrophes. Endodontic disasters will require special techniques to salvage them whereas catastrophes usually result in loss of the tooth and every effort should be made to prevent such problems from occurring. This presentation will cover common errors in endodontic procedures especially access opening, canal negotiation, canal irrigation, canal preparation, canal filling, post preparation.ration.

• The Journal of the Korean dental association
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• v.48 no.4
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• pp.288-296
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• 2010

Although non-surgical endodontic procedures have high success rates, failures do occur, These can be managed by root canal re-treatment or surgical intervention. Intentional replantation is an accepted endodontic treatment procedure in which a tooth is extracted and treated outside the oral cavity and then inserted into its socket to correct an obvious radiographic or clinical endodontic failure. Intentional replantation is indicated when other endodontic treatments performed to maintain the tooth have failed, or when endodontic periradicular surgery is not feasible. Intentional replantation may be particularly useful in these cases because these difficult to access areas can be maximally treated while the tooth is out of the mouth without damaging the periodontal attachment in adjacent teeth. In conclusion, intentional replantation is a reliable and even predictable procedure, and should be considered more often as a treatment modality in our efforts to maintain the natural dentition.

• Radiation Oncology Journal
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• v.35 no.4
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• pp.317-324
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• 2017

Purpose: This study evaluated outcomes of radiotherapy (RT) after chemotherapy in limited-stage head-and-neck diffuse large B-cell lymphoma (DLBCL). Materials and Methods: Eighty patients who were treated for limited-stage head-and-neck DLBCL with CHOP (n = 43) or R-CHOP (n = 37), were analyzed. After chemotherapy, RT was administered to the extended field (n = 60) or the involved field (n = 16), or the involved site (n = 4). The median dose of RT ranged from 36 Gy in case of those with a complete response, to 45-60 Gy in those with a partial response. Results: In all patients, the 5-year overall survival (OS) and disease-free survival (DFS) rates were 83.9% and 80.1%, respectively. In comparison with the CHOP regimen, the R-CHOP regimen showed a better 5-year DFS (86.5% vs. 73.9%, p = 0.027) and a lower rate of treatment failures (25.6% vs. 8.1%, p = 0.040). The volume (p = 0.047) and dose of RT (p < 0.001) were significantly reduced in patients treated with R-CHOP compared to that in those treated with CHOP. Conclusion: The outcomes of RT after chemotherapy with R-CHOP were better than those of CHOP regimen for limited-stage head-and-neck DLBCL. In patients treated with R-CHOP, a reduced RT dose and volume might be feasible without increasing treatment failures.