I own a canon 700d and recently I ended up causing a scratch (image attached) to it's body while fixing it to a tripod. My question is, is such a scratch or (dent?) bad for the longevity of my camera? is there a chance of such a scratch damaging the internal parts of the DSLR? It is very much a beginner's question and it may be coming from a place of panic but I would appreciate any help/advice. Thank you.
Your fine, nothing to worry about, the body will get the occasional scratch and it wont affect the internals just by scratching the body. The only way you should be worried about hurting the camera is based on how the scratch or dent happened, what I am saying is if you damage the outside by dropping the camera you may have busted something loose inside the camera that will hurt its operation. But a scratch from your tripod head plate would not do anything but change appearance, and the occasional scratch will happen.
