• Restorative Dentistry and Endodontics
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• 제48권1호
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• pp.10.1-10.9
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• 2023

Objectives: This study compared the buckling resistance of 3 nickel-titanium (NiTi) retreatment file systems and the torque/force generated during retreatment. Materials and Methods: The buckling resistance was compared among the D-RaCe (DR2), HyFlex Remover, and Mtwo R25/05 retreatment systems. J-shaped canals within resin blocks were prepared with ProTaper NEXT X3 and obturated by the single-cone technique with AH Plus. After 4 weeks, 4 mm of gutta-percha in the coronal aspect was removed with Gates-Glidden drills. Retreatment was then performed using DR1 (size 30, 10% taper) followed by DR2 (size 25, 4% taper), HyFlex Remover (size 30, 7% taper), or Mtrwo R25/05 (size 25, 5% taper) (15 specimens in each group). Further apical preparation was performed with WaveOne Gold Primary. The clockwise torque and upward force generated during retreatment were recorded. After retreatment, resin blocks were examined using stereomicroscopy, and the percentage of residual filling material in the canal area was calculated. Data were analyzed using 1-way analysis of variance with the Tukey test. Results: The HyFlex Remover files exhibited the greatest buckling resistance (p < 0.05), followed by the Mtwo R25/05. The HyFlex Remover and Mtwo R25/05 files generated the highest maximum clockwise torque and upward force, respectively (p < 0.05). The DR1 and DR2 files generated the least upward force and torque (p < 0.05). The percentage of residual filling material after retreatment was not significantly different between file systems (p > 0.05). Conclusions: NiTi retreatment instruments with higher buckling resistance generated greater clockwise torque and upward force.

• 구강회복응용과학지
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• 제27권1호
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• pp.99-107
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• 2011

비외과적 재근관치료의 주된 목표는 치근주변의 치유를 위하여 근관 공간을 완전히 멸균하는 것이며, 이 목표를 달성하기 위해서는 이전 충전물질의 완전한 제거가 요구된다. 전통적으로 근관충전물질의 제거는 스테인리스스틸 수기구를 통해서 이루어져 왔으며 이는 시간과 노력이 많이 소요되는 작업이다. 최근 보다 효율적인 근관충전물질의 제거를 위해 재치료용 회전식 NiTi 기구가 소개되었다. 이 연구에서는 만곡된 근관에서의 스테인리스스틸 수기구, ProTaper Universal Retreatment (Dentsply Maillefer, Ballaigues, Switzerland), Mtwo retreatment (Sweden & Martina, Padova, Italy)의 gutta-percha 제거 효율을 비교하였다. 재치료 후 근관 내 남겨진 gutta-percha의 양은 실험군 사이에 유의한 차이가 발견되지 않았다. 하지만 재치료에 소요된 시간은 재치료용 회전식 NiTi 기구를 이용한 실험군에서 더 적게 소요되는 것으로 나타났다.

• Tuberculosis and Respiratory Diseases
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• 제80권2호
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• pp.187-193
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• 2017

Background: Third-generation tyrosine kinase inhibitors of the epidermal growth factor receptor (EGFR-TKIs) have proved efficacious in treating non-small cell lung cancer (NSCLC) patients with acquired resistance resulting from the T790M mutation. However, since almost 50% patients with the acquired resistance do not harbor the T790M mutation, retreatment with first- or second-generation EGFR-TKIs may be a more viable therapeutic option. Here, we identified positive response predictors to retreatment, in patients who switched to a different EGFR-TKI, following initial treatment failure. Methods: This study retrospectively reviewed the medical records of 42 NSCLC patients with EGFR mutations, whose cancers had progressed following initial treatment with gefitinib or erlotinib, and who had switched to a different first-generation EGFR-TKI during subsequent retreatment. To identify high response rate predictors in the changed EGFR-TKI retreatment, we analyzed the relationship between clinical and demographic parameters, and positive clinical outcomes, following retreatment with EGFR-TKI. Results: Overall, 30 (71.4%) patients received gefitinib and 12 (28.6%) patients received erlotinib as their first EGFR-TKI treatment. Following retreatment with a different EGFR-TKI, the overall response and disease control rates were 21.4% and 64.3%, respectively. There was no significant association between their overall responses. The median progression-free survival (PFS) after retreatment was 2.0 months. However, PFS was significantly longer in patients whose time to progression was ${\geq}10months$ following initial EGFR-TKI treatment, who had a mutation of exon 19, or whose treatment interval was <90 days. Conclusion: In patients with acquired resistance to initial EGFR-TKI therapy, switched EGFR-TKI retreatment may be a salvage therapy for individuals possessing positive retreatment response predictors.

• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.332-341
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• 2017

Objectives: To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods: The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with ${\chi}^2$ tests using SPSS 21.0 software. Results: New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. Conclusions: This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

• Journal of Preventive Medicine and Public Health
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• 제15권1호
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• pp.139-143
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• 1982

A study was carried out in 81 retreatment patients with sputum positive pulmonary tuberculosis who had previously been treated with first-line drugs for more than one year at Health Center. The Following results were obtained; 1. Of the total 81 case of retreatment patients, male patients occupied 63(77.8%) and 18(22.2%) were female. Age group of $30{\sim}49$ years was 54.3% of total cases. 2. By extent of disease, moderate advanced cases were 53.1% and far advanced cases were 35.8%. 3. Of 81 patients admitted to the study. 65(80.3%) completed 1 year treatment 16(19.7%) patients discharged prematurely before 1 year. 4 patients terminated their treatment during $9{\sim}11$ months after registration. 4. Completment rate of chemotherapy was highest (90%) at age of under 30 years. 5. Intractable patients with persistant positive sputum test for A.F.B. even after 12 months of retreatment were occupied 9(13.8%) of total retreatment cases.

• Restorative Dentistry and Endodontics
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• 제43권1호
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• pp.5.1-5.9
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• 2018

Objectives: This study evaluated the amount of remaining root canal filling materials after retreatment procedures performed by undergraduate students using manual, rotary, and reciprocating techniques through micro-computed tomographic analysis. The incidence of instrument fracture and the instrumentation time were also evaluated. Materials and Methods: Thirty maxillary single rooted teeth were prepared with Reciproc R25 files and filled with gutta-percha and AH Plus sealer by the continuous wave of condensation technique. Then, the specimens were assigned to 3 groups (n = 10), according to the retreatment technique used: manual, rotary, and reciprocating groups, which used K-file, Mtwo retreatment file, and Reciproc file, respectively. Retreatments were performed by undergraduate students. The sample was scanned after root canal filling and retreatment procedures, and the images of the canals were examined to quantify the amount of remaining filling material. The incidence of instrument fracture and the instrumentation time were recorded. Results: Remaining filling material was observed in all specimens regardless of the technique used. The mean volume of remaining material was significantly lower in the Reciproc group than in the manual K-file and Mtwo retreatment groups (p < 0.05). The time required to achieve a satisfactory removal of canal filling material and refinement was significantly lower in the Mtwo retreatment and Reciproc groups (p < 0.05) when compared to the manual K-file group. No instrument fracture was observed in any of the groups. Conclusions: Reciproc was the most effective instrument in the removal of canal fillings after retreatments performed by undergraduate students.

• 구강회복응용과학지
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• 제38권4호
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• pp.213-221
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• 2022

목적: 근관 치료에 사용된 실러의 양과, 재치료용 NiTi 파일이 근관충전재의 제거 효율에 미치는 영향을 알아보고자 하였다. 연구 재료 및 방법: 발거된 소구치 중 단일 근관을 가지는 치아를 대상으로 하였다. #40/.06까지 근관 형성을 한 후, 무작위로 4 그룹으로 분류하였다. 근관충전재 중 실러가 차지하는 양을 다르게 하기 위해 그룹 별로 .06 taper 또는 .04 taper 거타퍼차를 칼슘실리케이트 실러인 Ceraseal과 함께 사용하여 single-cone 충전법으로 충전하였다. 그룹 별로 재치료용 NiTi 파일로는 ProTaper Universal Retreatment system (PTUR) 또는 Hyflex Remover (HR)를 사용하였다. 충전재 제거에 걸린 시간, 치근단 방출 잔사량, 근관 내의 충전재 잔존량을 측정하고 비교하였다. 결과: 근관치료에 사용된 실러의 양은 충전재 제거 효율에 영향을 미치지 않았다. HR 그룹은 PTUR 그룹보다 빠르게 충전재를 제거하였다. 치근단 방출 잔사량과 근관충전재 잔존량은 재치료용 NiTi 파일의 종류에 따라 유의한 차이를 보이지 않았다. 결론: 근관치료에 사용된 실러의 양은 제거 효율에 유의한 영향을 미치지 않았다. HR는 기존의 PTUR보다 빠르게 충전재를 제거했으며, 다른 제거 효율은 차이가 없었다.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.15.1-15.7
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• 2023

Objectives: This study evaluated the efficiency of WaveOne Primary files (Dentsply Sirona) for removing root canal fillings with 2 types of movement: reciprocating (RCP) and continuous counterclockwise rotation (CCR). Materials and Methods: Twenty mandibular incisors were prepared with a RCP instrument (25.08) and filled using the Tagger hybrid obturation technique. The teeth were retreated with a WaveOne Primary file and randomly allocated to 2 experimental retreatment groups (n = 10) according to movement type: RCP and CCR. The root canals were emptied of filling material in the first 3 steps of insertion, until reaching the working length. The timing of retreatment and procedure errors were recorded for all samples. The specimens were scanned before and after the retreatment procedure with micro-computed tomography to calculate the percentage and volume (mm³) of the residual filling material. The results were statistically evaluated using paired and independent t-tests, with a significance level set at 5%. Results: No significant difference was found in the timing of filling removal between the groups, with a mean of 322 seconds (RCP) and 327 seconds (CCR) (p < 0.05). There were 6 instrument fractures: 1 in a RCP motion file and 5 in continuous rotation files. The volumes of residual filling material were similar (9.94% for RCP and 15.94% for CCR; p > 0.05). Conclusions: The WaveOne Primary files used in retreatment performed similarly in both RCP and CCR movements. Neither movement type completely removed the obturation material, but the RCP movement provided greater safety.

• Tuberculosis and Respiratory Diseases
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• 제49권6호
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• pp.684-690
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• 2000

배경 : 폐결핵의 치료에 있어서 실패하는 가장 중요한 원인은 항결핵제의 조기중단과 불규칙적인 복용이다. 특히 재치료를 시행하는 환자는 장기간 동안 항결핵제를 규칙적으로 복용하는 것이 치료에 가장 중요하다. 본 연구는 재치료를 시행한 폐결핵 환자들의 재치료 실패의 원인이 될 수 있는 위험인자들을 알아내어 폐결핵의 재치료 성공률 향상과 더불어 난치성 관리에 대해 기초자료로 삼고자 하였다. 대상 및 방법 : 1994년 1월부터 1995년 12월까지 국립목포결핵병원에서 입원하여 재치료를 시행한 62명의 환자를 대상으로 하였다. 재치료에 실패한 환자군(1군)과 성공한 환자군(2군)으로 나누어 재치료 실패를 유발할 수 있는 인자들을 알아내기 위하여 성별, 연령, 과거의 치료력, 치료약제의 개수 및 내성 약제의 개수, 치료 약제중 살균제의 개수와 감수성이 있는 약제의 비율, 다재내성균의 발현율, 흉부 X-ray상 NTA 분류를 이용한 병변의 정도 및 공동의 유무등을 조사하여 독립표본 T-검정, ${\chi}^2$검정 및 Fisher의 정확확률 검정을 이용하여 비교 분석하였다. 결과 : 1군과 2군을 비교한 결과, 성별, 나이, 과거의 치료 실패율, 흉부 방사선 검사상 병변의 정도, 공동의 유무, 내성 약제의 개수, 치료약제중 감수성 약제의 비율과 감수성이 있는 살균제의 개수 및 다재내성균의 발현율에서 통계학적 유의성(p>0.05)은 관찰되지 않았다. 과거에 결핵치료를 받은 횟수에서는 1군에서 $2.4{\pm}0.8$, 2군에서 $1.6{\pm}0.9$로 통계학적 유의성(p<0.05)을 관찰할 수 있었다. 결론 : 폐결핵의 재치료 실패의 위험인자는 과거의 불규칙한 치료력임을 알 수 있었다. 따라서 재치료 실패를 감소시키기 위해서 초치료 폐결핵의 관리를 철저히 하여 실패하지 않도록 보다 큰 노력이 필요하다고 생각된다.

• Tuberculosis and Respiratory Diseases
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• 제40권4호
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• pp.404-409
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• 1993

연구배경 : 많은 재치료실패 환자들이 국립공주결핵병원에 입원해 있다. 그렇지만 이들에 대한 만족할만한 치료법이 없는 것이 현 실정이다. 이들에 대한 더 많은 관심과 적극적 대책이 필요하겠다. 방법 : 1992년 4월부터 1993년 2월까지 국립공주결핵병원에 입원하였던 재치료실패 환자 50명에 대하여 성별 및 연령별 분포, 질병기간, 항결핵제의 과거력, 약제내성, 병변의 크기, 조기중단 및 불규칙 복용의 이유 그리고 학력을 조사하였다. 결과: 1) 남녀의 비는 3:2였고 연령분포는 21~40세가 62%를 차지했다. 2) 28명(56%)이 10년이상의 질병기간을 가지고 있었다. 3) 모든 환자가 대부분의 항결핵제를 사용하였던 경험이 있었다. 4) RMP에 대한 내성은 96%에서, INH는 83%에서 나타났고 그밖의 항결핵제에 대한 내성은 6~67%에서 나타났다. 5) 48명(96%)이 중증으로 나타났다. 6) 초치료시는 28명(56%), 재치료시는 21명(42%)이 조기중단 및 불규칙 복용을 하였던 경험이 있었는데 그 이유는 초치료시는 '증상이 없어서'가 21명(75%) 이었고 재치료시는 '증상이 없어서'가 6명(29%), '생활이 바빠서'가 6명(29%) 그리고 '경제적 이유'가 3명(14%) 이었다. 7) 27(54%)이 고졸이상의 학력소유자이었다. 결론 : 치료실패를 방지하기 위하여 환자관리에 더 많은 노력이 필요하며 전염방지와 적절한 치료를 위하여 재치료실패 환자들에 대한 더 많은 지원과 입원치료가 필요하겠다.