Some people do give dog biscuits as chews - for helping to keep teeth trim. The ingredients of those sound ok - ie nothing nasty listed! But it does say 18.7% glucose - which is sugar basically. So personally I wouldn't want to give them very often - it might keep teeth trim but could also give tooth decay if too much sugar.
One type of dog chew that is good for hamsters and their teeth (and they all seem to go crazy for them) are the whimzee/antos mini sized dog chews - they come as mini toothbrush shapes or mini alligators. They are vegetable based and no sugar.
I don't know if Viovet ship to Ireland but they stock them. I tend to get 4 of the mini singles and give one maybe once a month.
https://www.viovet.co.uk/Antos_Cerea...+chews&sct_r=2
I tend to think of chews (for keeping teeth trim) as different from treats generally. Although some wood chew sticks also have food on them (the Rosewood naturals dandelion sticks are a favourite here - also sugar free).
For treats for taming I used to give the Rosewood little hearts, but pumpkin seeds are very popular for treats too
You can just get pumpkin seeds in the supermarket on the bakery counter.