CAJ | 학술논문

目的：??建立K锉、H锉和Protaper锉的三维有限元模型，分析其在弯曲根管中发生扭转断裂的原因与机制。方法???运用软件Pro/Engineer?5.0建立25号不锈钢K锉、25号不锈钢H锉及Protaper?F1锉切割刃全长的三维有限元模型；根据不同的弯曲角度和弯曲半径将其分为4组：30°/5?mm、30°/2?mm、45°/5?mm及45°/2?mm组，运行Pro/Mechanica有限元分析软件进行力量加载分析，观察顺螺纹及逆螺纹扭转负载下锉刃各部位的应力分布。结果???K锉和H锉在顺螺纹和逆螺纹2种受力条件下应力分布没有差别。K锉在45°/2?mm组的应力集中点位于切割刃尖；H锉在30°/5?mm和45°/5?mm组最大应力部位位于两切削刃的沟槽内，而在30°/2?mm和45°/2?mm组最大应力部位位于切削刃尖部，应力集中部位与扭转方向无关联；而在Protaper?F1锉组中，30°/2?mm和45°/5?mm组的最大应力部位在两切削刃的沟槽内，其余组的均位于切削刃尖部。结论??K锉和Protaper锉的对称截面设计有利于分散应力，而H锉的非对称截面设计易发生应力集中，在弯曲根管中受扭转负载时，后者更易断裂。
목적：??건립K촤、H촤화Protaper촤적삼유유한원모형，분석기재만곡근관중발생뉴전단렬적원인여궤제。방법???운용연건Pro/Engineer?5.0건립25호불수강K촤、25호불수강H촤급Protaper?F1촤절할인전장적삼유유한원모형；근거불동적만곡각도화만곡반경장기분위4조：30°/5?mm、30°/2?mm、45°/5?mm급45°/2?mm조，운행Pro/Mechanica유한원분석연건진행역량가재분석，관찰순라문급역라문뉴전부재하촤인각부위적응력분포。결과???K촤화H촤재순라문화역라문2충수력조건하응력분포몰유차별。K촤재45°/2?mm조적응력집중점위우절할인첨；H촤재30°/5?mm화45°/5?mm조최대응력부위위우량절삭인적구조내，이재30°/2?mm화45°/2?mm조최대응력부위위우절삭인첨부，응력집중부위여뉴전방향무관련；이재Protaper?F1촤조중，30°/2?mm화45°/5?mm조적최대응력부위재량절삭인적구조내，기여조적균위우절삭인첨부。결론??K촤화Protaper촤적대칭절면설계유리우분산응력，이H촤적비대칭절면설계역발생응력집중，재만곡근관중수뉴전부재시，후자경역단렬。
Objective??This?study?aimed?to?establish?finite?element?analysis(FEA)?models?of?the?K?file,?H?file,?and?Protaper?file,?and?analyze?the?factors?leading?to?the?breakdown?of?these?instruments?when?used?in?curved?root?canal.?Methods???Using?the?software?Pro/Engineer?5.0,?we?generated?three-dimensional?FEA?models?of?the?cutting?edges?of?the?stainless?steels?K?file,?H?file,?and?Ni-Ti?Protaper?file.?Curved?root?canals?were?classified?into?four?groups?according?to?the?angle?and?radius?of?the?curvature:?30°/5?mm,?30°/2?mm,?45°/5?mm,?and?45°/2?mm.?Pro/Mechanica?software?performed?the?FEA?on?the?mechanism?of?the?working?instrument?in?a?curved?root?canal.?Stress?distribution?in?the?cutting?edges?under?clockwise?and?counterclockwise?torsional?loads?was?analyzed.?Results??Similar?stress?distribution?patterns?were?observed?in?K?and?H?file?groups?regardless?of?the?direction?of?torsional?load,?either?clockwise?or?counter?clockwise.?In?the?45°/2?mm?group,?stress?on?the?K?file?is?concentrated?at?the?tip?of?the?cutting?blade.?However,?in?30°/5?mm?and?45°/5?mm?groups,?stress?on?the?H?file?is?concentrated?at?the?groove?between?two?cutting?edges,?whereas?in?30°/2?mm?and?45°/2?mm,?maximum?stress?is?located?at?the?tip?of?the?cutting?edge,?stress?positions?and?no?good?or?bad?times?to?reverse?the?direction?of?the?association.?In?F1?Group,?maximum?stress?is?located?at?the?cutting?edge?tip,?in?addition?to?groups(i.e.,?45°/5?mm?and?30°/2?mm)?where?stress?is?acting?on?the?groove?between?two?cutting?edges.?Conclusion??The?symmetric?cross-section?design?of?the?K?file?and?Protaper?file?is?beneficial?in?the?distribution?of?stress,?while?the?non-symme?triccross-section?design?of?the?H?file?is?prone?to?create?uneven?stress?distribution.?Thus,?the?latter?is?easier?to?break?when?used?in?a?curved?root?canal?and?under?torsional?load.