If a tooth has a cavity but no pain, should I fill the cavity or is just regular care enough? What are the disadvantages of tooth filling?

I'm looking for a wide array of dental services for both children and adults in Merced, CA such as soft tissue management, bonding, bridges, dentures, crowns, smile makeover, fillings, whitening, veneers, etc. If a tooth has a cavity but no pain, should I fill the cavity or is just regular care enough? What are the disadvantages of tooth filling?