Which method is least effective for sterilization in dental settings?

The ultrasonic method is primarily used for cleaning rather than sterilization. It employs high-frequency sound waves to agitate a fluid, which helps dislodge debris and contaminants from instruments, but it does not achieve the necessary temperatures or exposure times required to kill all microorganisms, including spores. In dental settings, effective sterilization is crucial for ensuring patient safety and preventing infections.

In contrast, steam autoclaving, dry heat, and chemical vapor methods are all recognized sterilization techniques that reach the required temperatures and exposure times to effectively kill a broad spectrum of pathogens, including resistant spores. Steam autoclaves utilize saturated steam under pressure, dry heat methods rely on high temperatures maintained over a period, and chemical vapor employs a combination of heat and chemical agents to achieve sterilization. Each of these methods is validated to ensure that dental instruments are rendered sterile and safe for use on patients.