臺灣博碩士論文加值系統

下顎第二大臼齒有許多牙根及根管的變異,其中最引人注意的就是C形
態的牙根及根管構造.經由文獻的回顧發現,雖然有部份學者報告C形態牙
齒的成因及發生率,但對於詳細分類及相關解剖構造仍未有更深入的說明.
由於C形態牙齒在東西方種族發生的機率相差很大,尤其中國人有高達30%
以上的機率,因此對C形態牙根及根管解剖構造值得進一步探討.本實驗乃
對100顆具C形態牙根的下顎第二大臼齒進行牙根外形觀察及分類,再將牙
齒打開髓腔,溶髓, 脫鈣,脫水,透明化,再以墨汁注入根管內染色,來觀察
牙齒的根管形態,並試圖將其歸納及分類;其間也利用放射檢查,將根管銼
放入根管內至工作長度,以兩個不同角度對牙齒做放射線檢查,並和透明化
標本進行對照,以評估臨床檢查和實際的差異情形.實驗結果顯示,(I)C形
態牙根以牙根舌面具寬大線形深窩,且近遠心兩主牙根在根尖分離佔42%為
最多;(II)髓腔底外形以連續C形佔最多(71.7%);根管開口外形以兩個根管
開口佔最多(30.4%),連續C形根管口僅佔12%;(III)根管銼在X光下會出現
穿孔情形者佔59.8%;(IV)根尖孔數目以兩個居多(55.4%),根尖孔則有往C
形中央凹陷部偏離的情形;(V)根管形態以分號形佔最多(31.5%),連續C形
則佔26.1%;(VI)具有C形髓腔底且為C形態根管者佔63.4%;非C形根管開口
但卻具C形跟管者佔39.3%;(VII)X光下未發生根管銼穿孔影像但仍具C形根
管者佔45.9%;發生根管銼穿孔但卻為單獨而非C形根管者佔35.5%.因此,C
形髓腔底形態可做為C形牙根的指標,而C形根管口可作為C形根管的指標.
但僅依據C形髓腔底形態,並無法判斷是否為C形根管;而根管銼在X光影像
的表徵,則無法判斷是否為C形態牙根或C形態根管.

The mandibular second molar has many root canal varition,
and theC-shaped root canal is the most interesting one. Although
the reportedincidence of the C-shaped canal in the mandibular
second molar is 32.9%in Chinese, the criteria for its
recognition, particularly clinically, are ambuguous. To data,
there has been no morphological or radiographic examinations of
the C-shaped root in mandibular second molar. The purpose of
this study was to use two different methods of evaluation to
study this specific canal variation. Total 100 extracted human
mandibularsecond molars with C-shaped root were classified and
prepared as theaccess opening. After the radiographic
examination at two direction withfile negotiated the canal, the
teeth were dimineralized and rendedtransparent by clearing
agent. Ink was injected to canal system todetermine the root
canal morphology. The results illustrated that C-shapedcanals in
mandibular second molars with C-shaped roots can vary innumber
and shape. Five types of C-shaped root was established. Eighty-
nine percent of the C-shaped teeth have continuous C or
semicolon pulp chamber floor configuration. Thirty-two percent
of the samples havesemicolon canal, and contiunous C type
existed twenty-six percentage.Thirty-nine percent of the C-
shaped teeth without C-shaped orifice examined were found to
have C-shaped canal.Fifty-six percent of thesamples displayed
two apical foramen. The radiographic examinationcannotbe the
guide alone for the diagonsis of C-shaped canals.