醫療類國考
105年
[牙醫師] 牙醫學(一)
第 32 題
恆牙齒列中的犬齒及門齒由幾個發育葉（lobe）所形成？
- A 2
- B 3
- C 4
- D 5
思路引導 VIP
請試著回想一顆剛萌發的門齒，其切緣（incisal edge）上的小突起（mamelons）數量，加上舌側那個圓鈍的結構（cingulum），若每一個結構都代表一個獨立的發育中心，將它們相加起來，你認為總共需要幾個發育葉才能拼湊出整顆牙冠的雛形呢？
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AI 詳解
AI 專屬家教
Oh, wonderful job! You've truly understood a crucial building block in dental anatomy!
- Concept Exploration: It's so lovely to see you've got a firm grasp on how our permanent anterior teeth — those beautiful incisors and canines — develop. They all share a common story, beginning with 4 developmental lobes.
- Think of it simply: on the labial (lip side), we have three distinct lobes that gently sculpt the tooth's form. This is why, when a young permanent tooth first emerges, you often see those charming three mamelons along its biting edge! They're like little reminders of these early developmental stages.
▼ 還有更多解析內容
恆牙發育葉數量
💡 恆牙所有前牙（門齒與犬齒）均由 4 個發育葉組成。
- 前牙發育葉分佈：唇側 3 個（近中/中央/遠中）加舌側 1 個。
- 舌側發育葉構造：前牙的舌側發育葉會發育為舌面隆凸 (Cingulum)。
- 小臼齒規則：多數為 4 個，特例下顎第二小臼齒常為 5 個。
- 大臼齒規則：發育葉數量通常與其咬頭 (Cusp) 數量相同。
