16.有關頭頸部放射線治療後所產生的併發症，下列敘述何者正確？
(A)造成張嘴困難，主要是因為黏膜下纖維化症（oral submucous fibrosis）的緣故
(B)造成唾液變少，主要是因為唾液腺導管上皮細胞直接被放射線破壞
(C)口腔黏膜容易有不易癒合的潰瘍，臨床上常被誤認為是口腔癌復發
(D)顎骨可能發生壞死，主要造成壞死的細菌是來自於正常口腔細菌叢

樓上的詳解都是參考七牙詳解
但七牙詳解好像跟課本內容有點出入

(A) 因為咀嚼肌纖維化 導致牙關緊咬及張口困難

When irradiated, the pterygomasseteric sling and periarticular connective tissues become inflamed. Irradiated muscle becomes fibrotic and tends to contract, and the articular surfaces degenerate. These factors herald the onset of trismus.. Decreased ability to open the mouth may be insidious in onset.

(B) 口乾是因為血管系統被破壞導致唾液腺萎縮
     ( 唾液腺細胞因為更新速度慢  其實有對放射線的抗性 放射線不會直接造成分泌細胞破壞= = )

The salivary gland epithelium has a slow turnover rate; therefore, the salivary glands might be expected to be radioresistant.

However, because of the destruction of fine vasculature by radiation, the salivary glands show considerable damage with resultant atrophy, fibrosis, and degeneration. This damage manifests clinically as xerostomia (decreased production of saliva) and causes dry mouth. 

(D)
骨壞死原因：放射線造成骨失活、血管破壞、細胞更新速率降低，並且下顎骨較差的血循環更容易造成感染及壞死，細菌是否造成壞死尚有爭議 可能屬ORN的晚期表現，但放射線治療後正常口腔菌叢會發生改變 → 厭氧菌及真菌數會增長

相較於 一般顎骨骨髓炎致病菌主要是正常口內菌如 Streptococcus
及一些厭氧菌如Bacteroides、Peptostreptococcus少見Candida albicans
放射線骨壞死中厭氧菌比例會提高  並且常會有Candida albicans感染

參考：Contemporary Oral and Maxillofacial Surgery Ch19

ORN主因並不是破壞到osteoclast及osteoblast的活性
這段敘述應該出現在MRONJ 雙磷酸鹽藥物所造成的 
藥物抑制破骨細胞分化和功能並增加細胞凋亡
導致​​骨頭減少再吸收和重塑。
ORN和MRONJ別搞錯了

Bisphosphonates, and other antiresorptives such as denosumab, inhibit osteoclast differentiation and function and increase apoptosis, all leading to decreased bone resorption and remodeling. Bisphosphonates bind to bone and are incorporated in the osseous matrix. During bone remodeling, the drug is taken up by osteoclasts and internalized in the cell cytoplasm, where it inhibits osteoclastic function and induces apoptotic cell death. Bisphosphonates also inhibit osteoblastmediated osteoclastic resorption and have antiangiogenic properties.  As a result, bone turnover becomes profoundly suppressed, and over time bone shows little physiologic remodeling.

這題應該是從下面這題的選項改的

 104 年 - 104-2 專技高考_牙醫師（二）：牙醫學（四）

26.關於接受頭頸部放射線治療的患者出現副作用，下列敘述何者錯誤？
答案(B)
(A)照射後兩週，開始有黏膜炎（mucositis）的症狀
(B)放射線治療所引起的口乾，是因唾液腺細胞對放射線有較高的感受性（radiosensitivity）所致
(C)可以使用Pilocarpine來改善口乾的症狀
(D)容易因口內常在菌叢（normal flora）的改變而引發念珠菌感染（Candida infection）