Is CD 12R 12 gage stranded wire suitable for use in an electric oven?
Use a dual-rated (TFFN/AWM) wire suitable for 105&deg;C

The bad news is you have the wrong wire (UL listed wires are marked, and your replacement wire isn't, so it's no good).  The good news is that we know two things here:


This wire is replacing wire within an appliance, so UL-listed Appliance Wiring Material (AWM) is the correct family of things to use
We have the old wire's temperature rating (105&deg;C)


Thus, we can safely use a dual-rated 16AWG stranded wire (TFFN/AWM) that has a 105&deg;C rating when used in an AWM application -- most TFFN sold today will be of the dual-rated type, but double-check the printing on the wire when you're buying it to make sure.