I want to do a video on this eventually to explain further, but I wanted to briefly point out a scientific discrepancy in the CGI series. The chipmunk characters don't have the correct number of teeth as their real life counterparts or any rodents for that matter. Instead, they have the exact same dental formula as humans.
For most mammals, a dental formula denotes the number of each kind of tooth in one quarter of an animal's jaws. Mammals have 4 different kinds of teeth: incisors, canines, premolars, and molars. Rodents of the sciuridae family (squirrels, chipmunks, marmots, and prairie dogs) have 20 teeth consisting of 4 incisors, no canines, 4 premolars, and 12 molars, giving them a dental ratio of 1:0:1:3. Humans and all other catharrine primates (humans, apes, and old world monkeys) have 32 teeth consisting of 8 incisors, 4 canines, 8 premolars, and 12 molars, giving them a dental formula of 2:1:2:3.
I cross referenced this shot of Theodore in the season 5 opening with two other instances where a large portion of the inner mouth is shown and found that the number and placement of teeth are consistent across the series and with all chipmunk characters. I have used colored brackets in the last image to denote each type of tooth. Green for incisors, red for canines, yellow for premolars, and blue for molars.
I know this may seem like I'm over-analyzing, but with their dental ratio being so specific to humans, this was likely intentional by the creators to make them more human-like and not simply a coincidence. I doubt there are any in-universe ramifications to this (unless you subscribe to the theory of them being mutants). Perhaps some other time I'll explain how I would describe their teeth in my scientifically plausible chipmunk design.