Final answer:
The upper carnassial teeth in dogs are triple-rooted and blade-like, designed for shearing flesh and bone, and are a unique adaptation for their carnivorous diet.
Step-by-step explanation:
The unique characteristic of upper carnassial teeth in dogs is that they are triple-rooted and blade-like. Carnassial teeth are not found in humans but are a specialized type of tooth found in some carnivorous animals, including dogs. In dogs, the carnassials are adapted for shearing tough material like flesh and bone; the upper carnassial, in particular, is part of the dog's premolars and molars which are typically used for grinding. This tooth works like a pair of scissors, allowing the dog to effectively cut through muscle and bone, aiding them in their carnivorous diet.