How much local anesthetic is there in a dental cartridge of 1% concentration (1.8 ml cartridge)?

To determine the amount of local anesthetic in a dental cartridge with a concentration of 1%, you start by understanding what the concentration means. A 1% solution indicates that there is 1 gram of anesthetic in 100 ml of solution. To find out how much anesthetic is in a smaller volume, such as a 1.8 ml cartridge, you can use the following calculation:

1. First, convert the percentage to a concentration in milligrams for clarity. Since 1% equals 10 mg/ml, we can directly say that in 1 ml of a 1% solution, there are 10 milligrams of the anesthetic.

2. Then, multiply the concentration (10 mg/ml) by the volume of the cartridge (1.8 ml):

( 10 , \text{mg/ml} \times 1.8 , \text{ml} = 18 , \text{mg} )

Thus, the amount of local anesthetic in a 1.8 ml cartridge of 1% solution is 18 mg. This calculation confirms that the correct answer is indeed 18 mg, which is why it is the right choice among the alternatives provided.