Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word: Think about your husband even if you don't have one. What's his name? It's Otto (おっと), and he's always leaving you at home because he's working at the auto (おっと) shop.
My husband has very healthy teeth.
My husband is such a wonderful man.
There you go again, always complaining about your husband.