If you have lost a tooth and your dentist has talked about crowns on the teeth either side of the gap, that can sound like a bad deal. It is not automatically one. There is more than one way to replace a missing tooth, and which one suits you depends on where the tooth is, the condition of your mouth, and how much time and money you want to spend.
Most adults have 28 to 32 natural teeth, with up to eight in each quadrant. The eighth tooth in a quadrant, when present, is the third molar, or wisdom tooth. Some people never have them, or have them removed because they are impacted.
Once a tooth is gone, you may want the gap filled. Here are the main options, including the one that sounds most drastic.
Leaving the gap open
Sometimes leaving a gap is the right call.
A missing wisdom tooth is the clearest case. It often has little essential chewing function, so most dentists do not recommend replacing it.
Some other gaps can be closed orthodontically. A dentist can move the neighbouring teeth together so the row of teeth looks complete again. This works particularly well when the teeth are already crowded, because straightening them and closing the space solve two problems at once. A remaining wisdom tooth can sometimes be moved forward into the gap.
The limitations are real. Not every case can be treated this way. It is also slower than other options and generally costs more, and closing gaps this way commonly takes two or three years or longer.
There is also tooth autotransplantation. A wisdom tooth that happens to need removing anyway can be extracted and immediately repositioned into the gap. Over time the tooth can become firm and function for many years. It is not applicable to many cases, and a dentist needs to assess whether the root shape and the surrounding bone allow it.
Replacing one tooth with one tooth
This is the most straightforward idea, and for many people it is the preferred option.
Dental implants are one of the most common ways to achieve it. An implant replaces the missing tooth in its own position, supporting a crown without cutting down the teeth on either side.
Removable partial dentures can do the same thing for a single tooth, and can also replace several teeth at once. They are cheaper, and they are sometimes used as an interim solution while a more permanent option is arranged. The trade-off is that they are taken out of the mouth, and many people find them uncomfortable.
Replacing one tooth with three
This is where the arithmetic of three comes from.
If an implant is out of reach financially, and a removable denture feels uncomfortable, a fixed bridge is a reasonable option.
The teeth on either side of the gap are prepared and crowned, and the three crowns are joined into a single unit. The two natural teeth act as abutments, and the crown spanning the gap is the pontic. Replacing one missing tooth therefore involves treating three teeth.
That does mean sacrificing healthy tooth structure in the two teeth beside the gap, which is a genuine cost and worth discussing. A bridge is not a wrong choice, though, and for some people it is the right one. It takes less time, costs less than an implant, and once fitted feels entirely normal. It is a sensible choice when the supporting teeth are already heavily restored, because they may need crowning eventually.
When more than one tooth is missing The same options apply, but the treatment becomes more complex, and several approaches may need to be combined.
If a gap has been left open for a long time, the teeth beside it drift and tilt into the space, which can leave too little room for an implant. In that case the teeth are usually straightened first, and the implant placed afterwards.
When all the teeth are missing, the choices include a conventional full removable denture; an implant-supported overdenture, which uses a few implants to hold a removable denture firmly in place; and, in some cases, a fixed implant-supported prosthesis. The overdenture option is worth knowing about: a conventional full denture can slip or come out when you laugh or speak, and a small number of implants can prevent exactly that.
The honest part
There is no single correct answer here, and any dentist who gives you one option and refuses to discuss the others is not giving you the full picture.
A dentist should explain what is feasible, what each approach involves, and roughly what each costs, and then respect your decision. The factors that decide this are usually money and time, and they are personal. The choice belongs to you.
Whichever option you end up with, the practical next step is the same: get a proper examination, including X-rays, so the plan is based on your own teeth rather than a general description.