What exactly is a crown?

When you need a dental crown or crowns, Life Smiles Dental Crowns in Plymouth, MN has you covered.

Do you think you need a crown?  What is a crown?  We often also hear from a patient, "Is a cap the same thing as a crown?"  They are one in the same, but dentists refer to them as crowns.  A crown is a full covering of a tooth, both on the entire chewing surface and surrounding it circumferentially.   Crowns for permanent teeth are custom made and look very natural.  Dental crowns can be done on any tooth in your mouth.

 Very similar to a crown (also called a full coverage crown)  is a partial crown.  Dentists often refer to them as an onlay or 3/4 crown.  Partial coverage crowns restore a portion of your tooth, but not fully.  The goal of both full and partial crowns is to restore natural esthetics and function for a long time.  Both full coverage and partial coverage crowns can be made at a dental laboratory or by an in-office milling unit.

 Baby teeth can also be saved by restoring with a crown.   Primary teeth are important for chewing, speech and for holding space until a permanent tooth can take it's place. The crowns for baby teeth (also called primary teeth) are prefabricated, which means it is not made by a lab.  One is selected for the size of the tooth the same day the decay is removed.  It is then shaped chair-side to fit more accurately and cemented in place.  Very commonly, baby teeth in the back of the mouth receive a crown that is made out of stainless steel and other alloys.  Baby teeth in the front of the most are likely made of a tooth colored (natural looking) composite resin.  In the past 10 years, some shift has taken place with some pediatric dentists offering tooth-colored crowns for your child's molars (back tooth).

Why would I need a crown?

The most common reasons are listed below:

  • You have a broken or fractured tooth
  • You have a tooth that doesn't have a visible crack, but hurts with biting
  • You have had a root canal (endodontic therapy)
  • You have a large filling with decay or fracture
  • You have a cavity under an existing crown
  • You lost a large filling
  • Your crown came off and is now missing (not super common)
  • You have a dental implant that needs to be restored
  • Your child has a baby tooth with decay on three sides
  • Your child is missing a corner of a front tooth

A less common reason, but very concerning to patients, is a metal allergy.  Crowns that have metal have a mixture of metals.  The original treating dentist most likely has a record of exactly what metal is in your crown, but another dentist will not be able to discern this.  When tissues show chronic inflammation that is localized to immediately around a crowns, it may be an allergy.  Gum disease and other causes must be ruled out prior to considering this as a potential allergy.  When these situations arise, we are careful to use a rubber dam or an Isovac to prevent inhalation or swallowing or inhalation of particles during replacement.

Crowns are often used in cosmetic cases to create beautiful smiles.  See below for an explanation of the difference between a veneer and a crown. We also sometimes use crowns to correct a person's bite (we call it occlusion).

Will it hurt?

You will be numbed (anesthetized) for your crown procedure so you will have no pain.  You remain awake and can watch TV or listen to music during your appointment. Afterwards, a small percentage of patients may experience hot or cold sensitivity or biting sensitivity in the first days after the procedures.   If your jaw gets tired easily after dental appointments, we recommend taking ibuprofen to prevent sore jaw muscles.  We care about your comfort and do everything we possibly can to make your crown appointment comfortable. On another note, oftentimes people have had root canals on the tooth being treated. Therefore, the tooth being treated has no nerve inside to cause sensations.  Some of these people choose to forgo the anesthetic because they won't feel a thing.   

A typical, single tooth crown appointment is called the "prep" appointment.  One hour is the approximate length of time in the dental chair for the prep.  After being numbed, your tooth is shaped with a dental handpiece.  If the tooth structure remaining after the prep is very small,  Dr. Geisler may need to do a procedure then called a build-up.  A build-up creates more height and width to help hold (or retain) a crown.  An digital impression is made of your prepped tooth and your opposing teeth. You get to see what your dentition looks like in 3D on the computer monitor.  In between two appointments, you will have a crown covering your tooth that protects it which looks and feels natural. Your permanent crown is then being custom crafted by a dental laboratory in Minnesota and will be ready for you in one to two weeks.   Your second visit is shorter than the first.  The exact fit is verified before it is bonded or cemented in place.  Of course, we ask your approval of the esthetics of your smile before that final check.  Here is a link to a helpful video to demonstrate a crown appointment.  Every situation and person is unique in dentistry, so please ask us questions.  We individualize our education for you to ensure you are comfortable prior to starting.  Our fees, along with estimate of insurance benefits (if applicable)  are also reviewed with you before starting.  We try hard to avoid surprising our patients at Life Smiles.

After having a root canal in a back tooth, a crown is nearly always recommended.  For front teeth, about 66% of teeth that require a crown for long-term success. We urge patients to not wait more than a month before crowning.  Teeth with root canals are more vulnerable to breaking badly causing the loss of the tooth.  Also, the temporary filling that is placed after the root canal will leak bacteria into the tooth over time, causing an infection.  You may not know if there is any problem with your root canal, that is one reason we take a film prior to commencing treatment.

What material are crowns made of?

So many different materials have been used in crowns have been made of over the past 100 years.  Gold crowns were very common for decades but are now losing favor over natural looking crowns.  As technology is advancing, all porcelain crowns are having even better long term results in strength than gold crowns.  Zirconia is a rapidly growing choice among dentists for a very strong restoration.  It is the stuff made famous for simulation diamonds.  It is a strong choice for many situations, because it the front a more translucent material can be layered over it to mimic natural teeth.  Almost all the crowns that are done at Life Smiles Family Dentistry in Plymouth, MN are all porcelain, for both it's beauty and durability.  Sometimes zirconia is used, and sometimes other porcelain systems (or brands to the public) are choosen.  In some situations, a porcelain with metal substructure is recommended, called a PFM (porcelain fused to metal) crown.  If a new crown is being placed in your mouth, you will have a choice and a full disclosure of materials. 

How often do crowns need to be replaced?

Dentists like to think that our crowns will last a lifetime, or at least 20 years!  But what the dental insurance industry has found out is that an average lifespan of a crown is eight years.  What I have seen in the fifteen years I have been practicing, is that rarely a crown by itself will fail (by breaking).  Trauma such as a car accident or sports trauma can fracture crowns.  Likewise, an undiagnosed grinding problem (bruxing) can also lead to fracture crowns.  The mouth is a tough place to live, it's humid, there is food sticking to surfaces, and acids passing by.  How a person takes care of their teeth gives me a much greater indicator than sticking to one guaranteed day.  Do you know someone who brushes and flosses after every meal and is meticulous about eating healthy and visits their dentist regularly?  The person you are thinking of could be married to a person who eats caramels all day, chews on ice at meals and chews gum the other waking hours.  Throw in a sipping of soda pop habit, and that nice new crown will not last as long as the first person's scenario.  Decay is the number one reason crowns are needed to be replaced.  A vulnerable spot in a person's dentition for getting a cavity is under the edge (margin) of a crown.  Maybe you knew that, but most are surprised to learn that you can still get a cavity under a crown.  Regular exams as well as great home care can ensure that you will not get decay under your crown.

As long as a crown fits well, contributes to a healthy bite, and looks great, it is doing it's job.  A crown doesn't need to be replaced due to age or to being gold or metal (unless an allergy is suspected.) Some people who prefer to have metal removed out of their teeth may request a change in a crown, but that is not routinely recommended.  I will work with you instead of against you in helping you achieve a healthy mouth, if you want your metal fillings or crowns replaced.  What is right for one person does not make it right for all, so discuss any questions you may have with your dentist. 

I have seen some crowns that were done over fifty years ago and are working really well.  On the flip side, I have seen an unchecked Mountain Dew addiction wreck havoc under the edge of crowns only a few years old.  The bottom line is, take care of your teeth!

What is the difference between crowns on natural teeth vs. dental implants?

The difference is in what lies under the crown.  Implant crowns have a titanium implant and a middle piece called an implant abutment, as the supporting substructure.  You can not get a cavity or decay on an implant.  However, it is possible to have a localized gum infection along an implant, called peri-implantitis.  A natural tooth root supports a typical full coverage crown.  Implants are long lasting and can support individual crowns to dentures and many variations in between.

What is a survey crown?

A crown can be created to have contours and attachments that a partial denture can be attached to.  These "survey crowns" are becoming less common as implants are growing in use to replace missing teeth over a removable partial denture.  Survey crowns help stabilize the fit of a partial denture so looseness is minimized.

Why do some people have a black line along the edge of their crown?

Good question!  The dark line at the edge, or margin, of a crown is likely the border of a metal substructure showing.  This is possible for porcelain fused to metal crowns.  The blackish-gray line can be avoided if the dentist requests a different design from the dental laboratory.   Although not often the case, stain from dark beverages could also be the cause.  Decay can also lead to discoloration, however it is usually not black.  

What is the difference between an onlay and a crown?

We like to save as much tooth structure as possible in the dental world.  By recommending a partial coverage crown, or onlay,  we are offering conservative treatment by not "drilling" your tooth as much.   Partial crowns are not always possible based on many factors.  The most common limiting factors is that there is a problem on all five surfaces of your tooth, or an existing full coverage crown needs replacement.

On the left is a full coverage porcelain crown for a upper central incisor, on the right is a porcelain veneer for an upper canine

On the left is a full coverage porcelain crown for a upper central incisor, on the right is a porcelain veneer for an upper canine

What is the difference between a crown and a veneer?

We are often asked if veneers and crowns are the same thing.  The two are different, but in some cases, both crowns and veneers are used to create a beautiful smile.  As you can see in the photo above and below, crowns are larger, covering 360 degrees of the tooth.  As mentioned above, crowns can be made of many materials.  However, veneers are made of porcelain. Veneers cover the entire front side of a tooth that is seen when smiling and over the edge of a tooth.  Oftentimes veneers slightly wrap between teeth.  Veneers can correct some crowding and spacing problems, lengthen teeth and change the color of teeth.  Some teeth require no drilling (prepping) for veneers.  Veneers are strong once bonded to a tooth.  Both crowns and veneers can last a long time if well taken care of.

View of the back and inside surfaces of a crown (left) and a veneer (right).

View of the back and inside surfaces of a crown (left) and a veneer (right).

 

The above information is general in nature and may not apply to you.  Talk to your dentist, or Dr. Krista Geisler, to answer your questions about a dental crown in Plymouth, MN.