Dental crowns in an hour? -

CAD/CAM technology makes it possible for a dentist to make and place a permanent crown in just one visit, possibly in about an hour. | How do one-appointment systems work? | Are single-visit crowns just as good as conventional ones?

The crown-in-1-hour procedure.

If you've read our page that outlines the steps of the crowning process you know that it typically takes two appointments, usually spaced about two weeks apart, for a dentist to make and place a dental crown for a patient.

As an alternative to this ordeal, some dentists offer crown-in-an-hour service where in just a single appointment, with the patient sitting in the dental chair for as little as an hour, the placement of a tooth's crown is fully completed (start to finish).

How are single-visit crowns possible?

In-one-hour placement is made possible via the application of CAD/CAM technology.

  • CAD stands for "computer aided design." - In the case of making crowns, a tooth's impression (copy of it in its trimmed form) is taken and fed into computer software where this information and stock tooth forms are melded to create the design of a customized crown for the patient.
  • CAM stands for "computer aided manufacturing." - In-an-hour restorations are fabricated using a milling machine that grinds them out of a single block of dental ceramic.

Actually, the materials and equipment needed to perform this service is not all that new. The first CAD/CAM dental units appeared on the market in the latter half of the 1980's.

What are some of the brand names associated with this technology?

The first brand to offer chairside (in-office) CAD/CAM dental units was Cerec®. Other brand names associated with chairside equipment are E4D®, Planmeca® and Galaxy Biomill®.


What are the steps of the crown-in-one-hour procedure?

Many of the steps performed when having a one-visit crown placed are exactly the same as those performed during conventional crowning technique. (You can reference those steps here.)

The 7 steps of in-an-hour (single-appointment) crown placement.
  1. Your tooth is first anesthetized (numbed up).
  2. Your dentist then "prepares" (shapes) your tooth using their dental drill.
  3. An (optical) impression of your prepared tooth is then taken and uploaded into the CAD software.
  4. The software proposes a design for your crown. Your dentist then refines and approves it.
  5. A block of dental ceramic that matches the shade of your teeth is placed in the CAM unit.
  6. The CAD software then directs the CAM milling machine in grinding the block down into the shape designed for your tooth.
  7. The finish of the restoration is then further refined and its fit evaluated. Once both steps have been completed, the crown is permanently cemented onto your tooth.

(CAD = computer aided design. CAM = computer aided manufacturing.)

Procedure differences: In-an-hour vs. conventional technique.

While similar, there are some very distinct differences between the steps of single-visit and conventional crown placement.

  • Optical impression taking. - With conventional technique, your dentist takes your tooth's impression by way of squishing impression putty over it and letting it set.

    With one-hour technique, the tooth's impression is acquired optically by taking a picture of it using a camera attached to the design (CAD) computer.

  • There's no need for a temporary crown. - Since your permanent crown is made and placed during the same appointment, there's no need for your dentist to place a temporary.
  • The way your tooth is prepared may be different. - By definition, a crown milled out of a single block of ceramic is an all-ceramic crown. And as such, the shape of the tooth it rests on, especially where its edges seat, must have a specific design for the best crowning outcome.

    To your dentist, this shape vs. what's needed for conventional (porcelain-metal or all-metal) crowns is quite significant. But to you, this difference will be so minute that it's unnoticeable.

How long does placing a single-appointment crown really take?

Despite what is often advertised, the phrase "crown in an hour" is really a bit of a misnomer when applied to this procedure.

  • Most single-tooth, one-visit crown placements probably take more along the line of 1.5 to 2.5 hours to actually complete.
  • The good news is that for some of the time (about 45 minutes or so during the middle of your appointment) you can be up and relaxing. This is the time period during which your crown is being designed, fabricated and finished.

Possibly the most truthful way to state this claim is that "in one hour" refers to about how much time you'll actually spend in your dentist's chair.


How good are single-visit, one-hour dental crowns?

Are they better than conventional ones?

No, not at all. What you're buying is the convenience of a relatively quick, one-appointment solution for your tooth's dental needs. There's nothing superior about the type of restoration placed. An equivalent crown could be made conventionally.

Are they worse?

No, probably not. Like we just stated, your new one-hour crown might be essentially identical to one your dentist would otherwise have placed using conventional technique.

The real answer to this question lies in coming to a conclusion about the following:

Does the type of all-ceramic crown that will be placed make an acceptable choice for your tooth?

As mentioned above, single-visit, 1-hour crowns are a type of all-ceramic restoration. Additionally, they have a monolithic construction, referring to the fact that they are milled out of a single block of ceramic. And while this type of construction does have some substantial advantages, it also has some distinct trade offs.

They can include factors such as crown strength, durability and esthetics, each of which can be significantly influenced by the specific type of ceramic that's used to make the crown. (We discuss these issues in detail here.)

Use the link above and educate yourself about this type of crown while keeping your own situation in mind. Then quiz your dentist as to if or why not your concerns can be expected to be an issue.

Having an all-ceramic crown placed can make a great choice in many situations. But only having to sit for one appointment may not be much of an advantage if your new restoration can't provide predictable, lasting service or only has a mediocre appearance.

What are the advantages of in-an-hour dental crowns?

a) Convenience.

One big advantage of single-visit crowns is that of convenience. Having one placed is one-stop shopping. In just a single appointment, all of your tooth's dental needs are taken care of.

b) Advantages of in-1-hour vs. conventional crown placement procedure.

Additional advantages have to do with how the procedure is performed. Some steps are different (and easier), others are omitted entirely.

  • Fewer dental shots. - Since you just have to sit through a single appointment to get your new crown, you won't have to have your tooth numbed up a second time during a following appointment.

    (Having said that, during the crown placement appointment associated with conventional crowning procedure, anesthetic isn't always required.)

  • Taking your tooth's impression is easier. - Because the information about your tooth's shape needs to be converted into digital form for the CAD software, impressions for one-visit restorations are taken optically via a hand-held camera (intraoral scanner) attached to the CAD/CAM unit.

    That means if you're prone to gagging when conventional impressions are taken (which involves trays filled with putty), you'll have one less hurdle to endure.

  • There's no need for a temporary crown. - Temporaries take at least a few minutes of time to make. And wearing one involves a whole set of potential problems and needed precautions.

    Because when single-visit technique is used a temporary isn't needed (because your crown will be made during your appointment), you reap the benefits of not having to have one.

Does getting a one-hour crown cost more?

Maybe, but not necessarily.

  • A dentist's fees for different types of crowns usually does vary (use the link for examples). But typically just by the restoration's type and not the fabrication method used.

    Having said that, due to the expense of the equipment needed to make in-office restorations, a dentist might find that they must charge more for placing in-one-hour crowns than they would for equivalent restorations crafted by a dental laboratory. (And therefore have a higher fee than surrounding dentists for all-ceramic crowns in general).

    However, this will most likely be determined by how much of this kind of work the dentist performs. High-volume practices will be in a better position to reap the rewards of efficiency and productivity that this technology can offer.

  • As a second scenario, due to a demand for one-hour service a dentist may find that they can charge more for single-visit crowns and therefore do.
 

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