Advice

Poppy and Oscar have irreversible dental disease. Although some rabbits are born with jaw defects, which can cause malocclusion (the term used for teeth that don't meet properly) and some suffer injuries which can do the same, the vast majority are damaged by incorrect feeding.
Too much commercial dry food is the culprit; convenient and easy to feed, it's easily done. Rabbits love it and will happily scoff as much as their doting owners can put in front of them, not realising the damage it causes. Dental disease like this cannot be cured; at best it can only be controlled with a strict diet, regular veterinary checks and surgery when necessary, which becomes a more frequent need as time goes on. Rabbits affected like this are unlikely to reach old age.
The following points will help you avoid this painful and distressing condition for your pet - PREVENTION IS BETTER THAN CURE.
1. Avoid overfeeding dry foods, NO FOOD IS A COMPLETE RABBIT FOOD DESPITE WHAT IT SAYS ON THE BAG! 75-80% of their diet must consist of grass and hay (dried grass, not to be confused with straw).
2. The average medium/large sized rabbit needs no more than one small handful of dry mix or pellets once a day. Giant breeds need no more than two handfuls, small dwarf breeds (i.e. Netherlands) half a handful. This ensures he stays hungry enough to graze all day on grass and hay which must ALWAYS be available. Constant chewing on grass and hay will provide the correct grinding action to keep teeth short, even and straight - it is the only way to ensure healthy teeth.
3. The minerals in grass and hay help provide good bone density to ensure jawbones hold the teeth firmly in place; any slight movement while chewing causes uneven growth which means sharp points called spurs will develop on the teeth. Spurs dig into the cheeks and tongue, very painful and distressing for the rabbit and corrected only buy surgery. Antibiotics are also needed to deal with the ulcers and sores on the cheeks and tongue. Expensive and entirely preventable!
4. Watch carefully for signs of dental problems; difficulty eating, weight loss, dribbling, pawing at the mouth, wet stained fur around the paws and mouth are all signs, as are one or both eyes weeping. Rogue tooth roots can put pressure on the tear ducts which run almost parallel to the upper jaw, causing them to overflow. Any of these symptoms much be checked by your vet promptly. Root problems are often seen in small faced dwarf breeds as their short, round skulls can struggle to accommodate the same number of teeth and roots as comfortably as the more traditional looking rabbits, whose jaws are longer and offer more space.
5. JUST KEEP IT SIMPLE treat them as rabbits, not over indulged children; grass, hay vegetables and a little fruit as a treat is all that is required. Pet shop treats, biscuits, toast etc are NOT healthy snacks and you do your pet no favours in the long run. Controlling their diet is the kindest thing you can do for them; dental disease and obesity through overfeeding are killers.