I'm 23. My right upper first molar was extracted 5 days ago. Do I need an implant?

Yes, a Dental implant is an ideal option in your case.
In case of non-restoration of that tooth, neighboring teeth will migrate.
and in the case of a bridge, you have to compromise two neighboring teeth.

hello - i would most certainly suggest replacing that tooth with either an implant or a bridge.  you need to regain form and function in this area and prevent shifting of teeth in the arch and these are the two fixed solutions available.  if you are missing multiple teeth you might want to consider a partial denture instead but that would not be recommended based on your age.  an implant would be best if you are a good candidate.  a bridge is good alternate if finances are an issue or if you are not a good candidate for an implant due to medical conditions or lack of bone in the area.  time is an issue as you will loose space and bone height between the adjacent tooth which will make placing an ideal restoration more difficult.  what i do for my patients that are interested in implants is place bone immediately into the tooth socket at that time of extraction and let it heal for several months.  when i see the patients at 4 months time there is good bone height and width as well as soft tissue to place an implant at that site.  the success rate usually very predictable.  this does not mean, however, that if you did not get a bone graft you can not necessarily get an implant in the future.  at this point i would suggest seeing to an oral surgeon or qualified dental professional for a complete clinical evaluation and to discuss all of your options.  good luck.  

Hello!
Because of your age I would suggest a dental implant for you to ensure the future health of your bone. As time goes on, your bone will recede from no internal stress, which is what the tooth root provided (and an implant would provide!). If a dental implant is out of your price range right now, I'd look into  bone grafting options to ensure that bone will be there when you are financially ready for implants.
Good luck!