歯内療法を行っていない歯の垂直性歯根破折の検出におけるコーンビームCTと周囲X線撮影の比較

A comparison of cone beam computed tomography and periapical radiography for the detection of vertical root fractures in nonendodontically treated teeth.

抄録

目的:

人工的に誘発された不完全歯根破折と完全歯根破折（VRF）の検出における、歯根周囲X線撮影とコーンビームCT（CBCT）の診断精度を生体外モデルで比較し、VRFの幅が画像システムの診断精度に影響を及ぼすかどうかを明らかにする。

AIMS: To compare in an ex vivo model, the diagnostic accuracy of periapical radiography and cone beam computed tomography (CBCT) for the detection of artificially induced incomplete and complete vertical root fractures (VRFs), and to determine whether the width of the VRFs had an impact on the diagnostic accuracy of the imaging systems.

方法:

歯内療法を行っていないヒト下顎前臼歯および大臼歯30歯に不完全歯根破折を誘発した。VRF幅は光干渉断層計を用いて測定した。このうち15歯に完全VRFを誘導した。破折誘発の前後に3D Accuitomoおよびi-CAT CBCTスキャンと周囲X線写真を撮影した。各撮影法についてROC（Receiver Operating Characteristic）分析を行った。さらに、感度、特異度、陽性・陰性予測値、検査者間・検査者内一致度を算出した。

METHODOLOGY: Incomplete VRFs were induced in 30 nonendodontically treated human mandibular premolar and molar teeth. VRF widths were measured using optical coherence tomography. Complete VRFs were induced in 15 of these teeth. 3D Accuitomo and i-CAT CBCT scans and periapical radiographs were taken prior to and after fracture induction. Receiver operating characteristic (ROC) analysis was carried for each imaging technique. In addition, values for sensitivity, specificity, positive and negative predictive values, inter- and intra-examiner agreement were calculated.

結果:

ROC分析では、不完全VRFの検出において、CBCTスキャナーはいずれも周囲X線撮影よりも有意に精度が高かった（P<0.05）。ROC曲線下面積（AUC）は、3D Accuitomoが0.687、i-CATが0.659、periapical radiographyが0.540であった。3D Accuitomo、i-CAT、periapical radiographyの感度は、それぞれ27%、28%、3%であった。不完全骨折の検出における検査者間一致率は、periapical radiography、3D Accuitomo、i-CATでそれぞれ0.020、0.229、0.333であった。いずれのCBCTスキャナーも、50μm以上のVRFの検出において、50μm未満のVRFと比較して有意に正確であった（P<0.01）。50μm未満のVRFの検出では、3D Accuitomoがi-CATより有意に優れていた（P<0.05）。完全骨折では、3D Accuitomo（0.999）およびi-CAT（0.998）のAUC値は、智歯周囲X線撮影（0.724）よりも有意に高かった（P<0.05）。

RESULTS: In the ROC analysis, both CBCT scanners were significantly more accurate than periapical radiography for the detection of incomplete VRFs (P < 0.05). The overall area under the ROC curve (AUC) values for 3D Accuitomo, i-CAT and periapical radiography were 0.687, 0.659 and 0.540, respectively. The sensitivity of 3D Accuitomo, i-CAT and periapical radiography was 27%, 28% and 3% respectively. Interexaminer agreement for the detection of incomplete fractures with periapical radiographs, 3D Accuitomo and i-CAT was 0.020, 0.229 and 0.333, respectively. Both CBCT scanners were significantly more accurate (P < 0.01) in detecting VRFs of ≥50 μm compared with VRFs of <50 μm. 3D Accuitomo was significantly better than i-CAT in detecting VRFs of <50 μm (P < 0.05). For complete fractures, the AUC values for 3D Accuitomo (0.999) and i-CAT (0.998) were significantly higher (P < 0.05) than for periapical radiography (0.724).

結論:

この生体外研究の条件下では、模擬不完全VRFの検出において、智歯周囲X線写真とCBCTは信頼性に欠けるものであった。破折の幅は、50μm以上のVRFの検出が50μm未満のものより有意に高かったことから、CBCTの診断精度に影響を及ぼすようであった。完全骨折の検出は、すべてのシステムで不完全骨折の検出よりも有意に高かった。

CONCLUSIONS: Under the conditions of this ex vivo study, periapical radiographs and CBCT were unreliable for the detection of simulated incomplete VRFs. The widths of the fractures appeared to have an impact on the diagnostic accuracy of CBCT as the detection of VRFs of ≥50 μm was significantly higher than those of <50 μm. The detection of complete fractures was significantly higher for all systems than that of incomplete fractures.