Updated: May 20, 2021
One of the most important pieces of equipment in your office is the sterilizer. Without sterile instruments, one can't practice dentistry. Most offices have an autoclave to sterilize instruments. As you probably know, an autoclave uses super-heated steam under pressure to sterilize instruments. An autoclave typically sterilizes at 270-275F. Most autoclaves will also have a "plastics" cycle as cool as 250 F. Many can even be programmed to run cooler than that.
At 270 F an autoclave only requires about 3 minutes to render unwrapped instruments "sterile". Most of the time, the load is wrapped (bagged or otherwise packaged) as the instruments are not expected to be put into use as soon as they are removed from the sterilizer (a requirement if not packaged, otherwise they will no longer be considered "sterile"). If wrapped, most steam sterilizers are expected to run for 6 minutes at 275 F and 30 psi to achieve "overkill". When adding in time for heat-up and drying, most cycles are 15-20 minutes in total, but only 7 minutes is spent in actual sterilization.
The time required to sterilize will increase as the temperature goes down, of course. For example, at 250F the actually sterilization portion of the cycle (with wrapped instruments) increases to a full 30 minutes. Note the temperature resistance of what you are sterilizing and set the appropriate cycle for your load.
Some sterilizers are advertised as being faster than others. The reality is, the 2-3 minute time for unwrapped loads can't really be improved upon. One can skip the drying stage and run cycles back to back so the sterilizer starts from warm to reduce net cycle times. Most sterilizers can complete sterilization in well under 10 minutes (if unwrapped) so buying a special "rapid" sterilizer may not be the best investment when it's just a matter of learning how to use what you probably already have.
All of the above numbers are for a Gravity-Displacement type autoclave, the most commonly used in the dental industry. A Pre-vacuum sterilizer (also known as "Type B") can improve cycle times.
For further information, I recommend checking the CDC's Guidelines to Sterilization and Disinfection in Healthcare Facilities.