55.下列有關牙周病預後的敘述，何者錯誤？
(A)牙齒解剖形態，當有牙根分叉侵犯，有愈長的牙根幹部（root trunk）預後愈佳
(B)牙周治療患者因骨喪失而使牙齒的旋轉中心下降，比旋轉中心靠牙冠的牙齒預後較差
(C)當患者因治療牙周病過程中停止抽菸，可改善其治療預後
(D)發育溝、牙根太靠近（root proximity）、牙根分叉侵犯，均因較無法執行清潔而預後較差

(A)細菌容易躲藏在牙根分岔處,牙根幹越長意味著牙根分岔處越下面,清潔也就越不容易,預後差才對

(B)正確：根據Carranza's clinical periodontoly p.376

The center of rotation of the tooth  be nearer the crown results in a more favorable distribution of forces to the periodontium and less tooth mobility.

因此旋轉中心靠牙冠的牙齒預後較好

(C)正確：根據Carranza's clinical periodontoly p.377

Patients with slight-to-moderate periodontitis who stop smoking can often be upgraded to a good prognosis, whereas those with severe periodontitis who stop smoking may be upgraded to a fair prognosis.

(D)正確：根據Carranza's clinical periodontoly p.378

Ａnatomic considerations that present accessibility problems are developmental grooves, root proximity, and furcation involvements. The presence of any of these can worsen the prognosis.