**Core Concept**
Primary prevention in dentistry refers to measures taken to prevent the occurrence of dental diseases or conditions. This approach focuses on maintaining good oral health and preventing the progression of disease. In contrast, secondary prevention aims to detect and treat problems early, while tertiary prevention seeks to manage and alleviate established conditions.

**Why the Correct Answer is Right**
The correct answer, wearing gloves and sterilization of the instruments, is an example of primary prevention in dentistry. This practice helps prevent the transmission of infectious diseases, such as HIV and hepatitis, from patient to dentist or vice versa. By maintaining asepsis in the dental setting, the risk of cross-contamination is significantly reduced, thereby protecting both patients and dental professionals. This is achieved through proper hand hygiene, the use of personal protective equipment (PPE), and the sterilization of dental instruments.

**Why Each Wrong Option is Incorrect**
**Option A:** Scaling & polishing and filling are examples of secondary prevention, as they aim to treat existing conditions, such as plaque and tartar buildup, rather than preventing them from occurring in the first place.

**Option B:** Extractions, root canal treatments (RCT), and periodontal surgeries are examples of tertiary prevention, as they address established dental problems and seek to alleviate symptoms or manage disease progression.

**Option D:** Replacements of Lost teeth and orthodontic treatments are also examples of tertiary prevention, as they aim to restore function and aesthetics in patients with existing dental problems.

**Clinical Pearl / High-Yield Fact**
To remember the distinction between primary, secondary, and tertiary prevention in dentistry, consider the following analogy: primary prevention is like locking the door to prevent intruders, secondary prevention is like having a security system to detect and deter intruders, and tertiary prevention is like repairing the damage after the intruders have entered.

**✓ Correct Answer: C. Wearing gloves and sterilization of the instruments**