You really must keep this in perspective. Any piggie is only here for as long as they're here. There are no guarantees. Life with a dental piggie can be even more uncertain.For example, Archie needs a lot of extra help and his dental issues most likely started due to some other problem, but he's been here with me for about 16 months now and his needs are managed. How long will he be here for? Who knows, but as long as he has a good life while he is here then that's all that matters.
When Oscar was here with me, just a week ago, he needed encouragement to start eating but once he started he ate well. Rather than give too much syringe food, that he is likely to become reliant on, I would hand feed him as much veg as possible. Feed him away from the rest of the herd and let him eat at his own pace. The fact that he's needed very little dental work doing at the last two appointments is very encouraging as it means he must be using his teeth.
Keep an eye on his weight, but don't worry about the loss of few grams here and there. If generally his weight is stable then that's fine.
Please don't get yourself into a state over this. Oscar is still a big, strong piggie who just needs a bit of extra encouragement. Yes, there could be some other issue, but as long as this can be worked around then it's business as usual. If I thought too much about what might be round the next corner with my 'extra needs' gang, then I would be teetering on the edge, or completely falling over it!
Please don't view Oscar as a piggie with a limited life, but as a normal piggie who just needs a bit of extra help at times.