Can you over bake bread?

Lots of different thermometers will more-or-less work. If the one you have is easy to use, hasn't melted, and seems to read relatively accurately, that's good enough.

My personal favorite is an el-cheapo mechanical instant-read  ...although asking TFL what's the "best" thermometer may be inviting a religious war:-)

Many cooking thermometers expect to have their probe but not their dial very hot, and will screw up (even melt) if placed in an oven.

• Separate in-oven meat thermometers are sometimes rather heavy and want to be vertical, so it's hard to poke them into a flattish dough and have them stay upright (especially staying away from the inside of the crust on the other side).
• The pop-up meat thermometers used for Thanksgiving turkeys have some problems:
  • They're probably not quite accurate enough
  • They're fixed to one particular temperature, and that temperature isn't the right one for bread
  • They're almost impossible to get outside of holiday season
• Some of the newer meat thermometers have two parts - a sensor that goes in what you're baking and a readout/alarm part that stays outside the oven - connected by a cable that can take the heat. In my experience these may bring up either of two problems:
  • The cable can be a major pain. I caught it on the oven door and pulled a lump of fresh dough onto the floor of my oven just once  ...that was enough for me. (others may feel quite differently though)
  • The metal temperature sensor tends to conduct a little bit of heat from outside the loaf (for example from your baking stone), and so read a few degrees too high. When you're trying to differentiate 204F from 207F, a thermometer that sometimes reads up to eight degrees too high can be quite frustrating.(IMHO, this is what leads to those puzzling reports of internal crumb temperatures well above the boiling point of water:-)
• "Instant read" thermometers are made with three  different technologies, and so come in three quite different subtypes. In every case though, be sure to take the loaf out of the oven to measure its temperature, and never put the thermometer in the oven.
  
  • One technology uses a thermocouple; the Thermapen brand currently has much of this market. It's very fast, settling to its final reading  in only a few seconds  ...but it's rather pricey too. Watching for sales is a good idea, but even at a sale price they cost more than many home bakers want to pay.
  • The other electronic technology uses a thermistor. It's much much cheaper (often less than $10, I found one for less than $4!), but it takes longer: up to10 seconds to get "close" and up to 30 seconds to stop changing altogether.
  • There's also the old non-digital technology, just a mechanical dial. In my experience these work surprisingly well  ...but many stores don't carry them any more.
• Candy thermometers expect to clip to the side of a pan.
• Refrigerator/freezer thermometers won't register high enough temperatures.
• Oven thermometers usually have either a stand or a hanger (or both) but not a long skinny probe, so there's no way to poke them into the inside of a loaf.