Mesial slope of distobuccal cusp of maxillary first molar meets its distal slope at ______________ angle
## **Core Concept**
The question pertains to the morphology of the maxillary first molar, specifically the angle formed by the mesial slope of the distobuccal cusp and its distal slope. Understanding dental anatomy, particularly the structural details of teeth, is crucial for various dental procedures and restorations.
## **Why the Correct Answer is Right**
The correct answer, **135 degrees**, is based on the typical anatomical configuration of the maxillary first molar. The distobuccal cusp of this tooth has specific slopes that meet at a particular angle. This angle is significant in dental anatomy as it helps in the identification and classification of teeth, which is essential for dental restorations, prosthodontics, and orthodontics. The mesial slope of the distobuccal cusp and its distal slope forming a **135-degree angle** is a characteristic feature that dental students and professionals must recognize.
## **Why Each Wrong Option is Incorrect**
- **Option A: 45 degrees** - This angle is too acute for the described cusp configuration of the maxillary first molar. Angles of 45 degrees are more commonly associated with other anatomical features or inclinations not specific to this particular cusp relationship.
- **Option B: 90 degrees** - A right angle of 90 degrees does not accurately describe the typical angle formed by the mesial and distal slopes of the distobuccal cusp of the maxillary first molar. This option underestimates the angle.
- **Option D: 180 degrees** - This option suggests a straight line, which is not applicable to the description of the slopes meeting at an angle.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the maxillary first molar often has a distinctive morphology, including the configuration of its cusps and grooves. Recognizing these features, such as the **135-degree angle** formed by the slopes of the distobuccal cusp, is essential for dental identification, restorative dentistry, and understanding occlusal relationships.
## **Correct Answer: C. 135 degrees**