Final answer:
The best recommended method for sterilizing dental handpieces is autoclaving, as it's the most effective form of sterilization, fully eliminating all forms of microbial life without damaging the instruments.
Step-by-step explanation:
Recommended methods for sterilizing dental handpieces include autoclaving, which is considered the most effective method of sterilization. Autoclaves utilize moist-heat to raise temperatures above the boiling point of water, eliminating all forms of microbial life, including resistant structures like endospores. While chemical disinfection and dry heat sterilization are other methods of controlling microbial growth, they are not the preferred choice for dental handpieces due to either the potential damage to the instrument or the less effective microbial control compared to autoclaving. Therefore, the correct answer here is 1) Autoclaving, as it offers comprehensive sterilization without damaging the sensitive instruments. Nonetheless, manufacturers' recommendations and regulatory standards should always be followed for the sterilization of dental equipment.