The number of line angles in a permanent maxillary central incisor is
**Core Concept**
The number of line angles in a tooth refers to the angular points where the tooth's surfaces meet. In permanent maxillary central incisors, line angles are defined by the junctions of the facial, lingual, mesial, distal, and occlusal surfaces.
**Why the Correct Answer is Right**
The permanent maxillary central incisor has six distinct line angles: two on the facial surface (mesial and distal), two on the lingual surface (mesial and distal), and two at the occlusal corners (one at the mesial and one at the distal). These are formed by the intersection of the incisal edge with the adjacent surfaces. This pattern is consistent across normal, healthy maxillary central incisors and is a key feature in dental anatomy for diagnosis and restorative planning.
**Why Each Wrong Option is Incorrect**
Option A: Two – This is incorrect because it underestimates the number of junctions; only two are not sufficient to represent the full surface geometry.
Option B: Four – This misses the two lingual line angles and fails to account for the occlusal corners.
Option D: Eight – This is excessive; no standard anatomical structure in this tooth has eight line angles.
**Clinical Pearl / High-Yield Fact**
Maxillary central incisors have the most line angles among anterior teeth, making them critical for assessing tooth morphology during restorations and crown preparations. Remember: **"Facial, lingual, mesial, distal, occlusal corners"** — each corner contributes to the count.
✓ Correct Answer: C. Six