#4 premolar Working length and electronic apex locator.ppt

Premolar WL & EAL

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2. Electronic Apex Locator
2014.10.17

3. The Rational for Electronic Apex Locators
•The electronic resistance of the mucous membrane
and the periodontium is constant.
•No individual technique is truly satisfactory in WL
determination.
Gordon 2004
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3. minor constriction
(CDJ)
a->b->c 同一顆牙越來越老

4. The Components of RooZx
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Contrary Electrode(為唇鉤)
接到白色的 probe cord
connector上，而灰色的 File
Holder Plug接到灰色的
probe cord connector
上。

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唇鉤與水接觸 (水為導電的物
質，用以模擬臨床口腔環境 )，
相對應的臨床步驟則是將唇鉤

掛在病人的嘴角。

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Root ZX是以閃爍指標減
0.5~1mm的方式來決定工作長度。

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9. Premolar WL Determination
2014.10.17

10. Materials
•A lower premolar及X光片
•High speed and no.557, no.700L burs
•Low speed handpiece and no.291 bur
•Endodontic explorer (DG16)
•至少#15 K-file (請使用21mm或25mm的file)
•Irrigation
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11. Procedure
•Estimate the length from occlusal surface to
chamber roof.
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12. 觀察牙齒型態
•下顎小臼齒須注意牙冠部分有向舌側傾斜的現象
(lingual inclination)
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上下小臼齒皆為橢圓形的髓腔開擴
90% 2 canal

13. 達到初步的 strait-line access
•Remove cervical ledge/collar. 自行以DG-16檢查亦
可使用#291bur, GG drill #2->#3->#4
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14. The proper working length distance
•No bone or root resorption:
–1 mm1 mm from apex
•Bone but no root resorption:
–1.5 mm1.5 mm from apex
•Bone and root resorption:
–2 mm2 mm from apex
•Teeth for endo lab: 1Teeth for endo lab: 1 mm from apexmm from apex

15. 拍攝X光片
•拍攝正照及 M shift (X光射線由 M往D發射)
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16. 16
正照 M shift

17. 填寫special chart
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18. 評分標準
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•Access opening
磨去過多齒質
髓腔穿孔 (perforation)
未找到所有根管口
•Working length determination
不正確的工作長度
Use #10 file
未將雙根管分開 (需拍攝正照及 M shift)
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19. 打成績
•口外牙
•Mounted X-ray film (initial & WL film)
•成績單
•評估WL的表格
•Endodontic explorer (DG16)
•時間：16:00~17:00 逾時不候下次上課補打
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