As of 1st February 2018, medicines containing codeine will only be available via a prescription. There are good reasons for doing this, most importantly that there is strong evidence that alternative medicines such as Paracetamol plus Ibuprofen are more effective in controlling strong dental pain.
Added to the problems with codeine such as tolerance (needing a higher dose to have the same affect) and withdrawal issues we need to be careful with what we take for dental pain. Consult with your Doctor, Dentist or Pharmacist to be better informed as to the best option for you.
For more information see https://www.nps.org.au/medical-info/consumer-info/medicines-with-codeine-what-you-need-to-know