Final answer:
Codeine, often combined with non-opioid pain relievers, is an appropriate choice for controlling dentally related pain in clients with hypothyroid conditions.
Step-by-step explanation:
An appropriate opioid to use for controlling dentally related pain in hypothyroid clients is codeine, particularly in combination with non-opioid pain relievers.
Opioids such as morphine and codeine, derived from the opium poppy, have potent analgesic properties, hence are effective in managing moderate to severe pain. Morphine is typically used for more severe pain, often in a surgical setting, while codeine is common for mild to moderate pain, and is often formulated in combination with acetaminophen or other non-opioid medications. It is important to consider the potential for abuse with opioids and to use them responsibly under medical supervision.