S M Shen1,2, M Deng2,3, P P Wang2,4, X M Chen5,6, L W Zheng2,7, H L Li7. 1. Department of Endodontic and Operative Dentistry, Tianjin Stomatological Hospital, Tianjin, China. 2. State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China. 3. Department of Oral Biology, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. 4. Department of Periodontology, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China. 5. State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China. chenxinmei61@126.com. 6. Department of Endodontic and Operative Dentistry, West China Hospital of Stomatology, Chengdu, China. chenxinmei61@126.com. 7. Department of Endodontic and Operative Dentistry, West China Hospital of Stomatology, Chengdu, China.
Abstract
AIM: The aim was to evaluate the incidence and type of defects that occurred with K3 rotary nickel-titanium instruments during routine clinical use. METHODOLOGY: A total of 2397 K3 (G-PACKS, SybronEndo, West Collins, Orange, CA, USA) instruments were collected from a graduate endodontic clinic over 21 months. All the instruments were limited to a maximum use of 30 canal preparations. The collected instruments were measured by a digital caliper to determine whether any fractures had occurred and then were visually inspected for deformation and fracture under a stereomicroscope. The surfaces of fractured instruments were further evaluated under a scanning electron microscope. Data were analysed using chi-square test and Kruskal-Wallis test. RESULTS: The incidence of instrument defect was 5.63%, consisting of 3.59% fractures and 2.05% deformations. The defect rates of 0.04 and 0.06 files were statistically higher than the other taper groups (P < 0.003) except for 0.08 files (P > 0.05). For the fractured instruments, 63.95% failed from flexural fatigue, whilst 36.05% failed from torsion. CONCLUSION: Flexural fracture was the major mode of fracture for instruments with larger taper. A routine check for instrument integrity particularly for 0.04 and 0.06 files at high magnification is recommended after each clinical use.
AIM: The aim was to evaluate the incidence and type of defects that occurred with K3 rotary nickel-titanium instruments during routine clinical use. METHODOLOGY: A total of 2397 K3 (G-PACKS, SybronEndo, West Collins, Orange, CA, USA) instruments were collected from a graduate endodontic clinic over 21 months. All the instruments were limited to a maximum use of 30 canal preparations. The collected instruments were measured by a digital caliper to determine whether any fractures had occurred and then were visually inspected for deformation and fracture under a stereomicroscope. The surfaces of fractured instruments were further evaluated under a scanning electron microscope. Data were analysed using chi-square test and Kruskal-Wallis test. RESULTS: The incidence of instrument defect was 5.63%, consisting of 3.59% fractures and 2.05% deformations. The defect rates of 0.04 and 0.06 files were statistically higher than the other taper groups (P < 0.003) except for 0.08 files (P > 0.05). For the fractured instruments, 63.95% failed from flexural fatigue, whilst 36.05% failed from torsion. CONCLUSION: Flexural fracture was the major mode of fracture for instruments with larger taper. A routine check for instrument integrity particularly for 0.04 and 0.06 files at high magnification is recommended after each clinical use.