**Core Concept**
The recommended angle of root end resection is a critical factor in endodontic surgery, as it affects the long-term success of the procedure. The angle of resection influences the preservation of the periodontal ligament, the integrity of the surrounding bone, and the overall healing of the surgical site.

**Why the Correct Answer is Right**
The correct angle of root end resection is typically between 0-10 degrees, with a recommended angle of 5 degrees. This minimally invasive approach preserves the periodontal ligament and surrounding bone, promoting a more favorable environment for healing. The optimal angle allows for the removal of the damaged or infected root tip while minimizing the risk of damage to the surrounding structures.

**Why Each Wrong Option is Incorrect**
**Option A:** An angle of 30-40 degrees is too aggressive and may lead to excessive bone loss, compromising the long-term stability of the tooth.
**Option B:** An angle of 90 degrees is too vertical and may result in a more extensive resection, increasing the risk of damage to the surrounding bone and periodontal ligament.
**Option C:** An angle of 60 degrees is too shallow and may not effectively remove the damaged or infected root tip, potentially leading to persistent infection or inflammation.

**Clinical Pearl / High-Yield Fact**
When performing root end resection, it is essential to use a high-speed bur and a gentle touch to minimize damage to the surrounding bone and periodontal ligament. Aiming for a 5-degree angle of resection will help ensure a successful outcome and promote optimal healing.

**Correct Answer: C. 60 degrees is too shallow and may not effectively remove the damaged or infected root tip, potentially leading to persistent infection or inflammation.**