What is a Dental Crown?
Simply put, a crown is a small tooth-shaped cap that your dentist will use to cover one of your teeth. Crowns are used to restore the strength, size, and shape of a tooth. It will be custom-made by your dentist out of a durable material.
Every tooth is basically made up of two parts called the crown and the root. For people who brush and floss regularly, the roots of your teeth are concealed by the gum line, just like how a tree’s roots are under the soil. The crown is simply the part of the tooth that you can see. Your teeth aren’t even bones (they are stronger than them); the crown is made up of a calcified tissue called dentin covered by a shiny external layer of enamel. Just like the natural tooth structure, a crown will cover the entire tooth from the gum line up to protect the sensitive pulp and nerves contained inside of it.
Why Would I Need a Dental Crown?
As we mentioned in the last section, the crown is meant to protect the internal structures, like the nerves, of your tooth. A crown made by your doctor serves the same purpose. Specifically, you might need a crown in one of the following situations (this isn’t a complete list but just the most common reasons):
1. Dental bridge: Like an actual bridge, a dental bridge is a partial denture that is meant to link the empty gap between two teeth. If left alone, neighboring teeth will shift toward the gap and this will cause pain and/or change your bite strength.
The two teeth on either end of the bridge are called abutments and they will either be false teeth or, you probably guessed it, your dentist will have your natural teeth outfitted with crowns to increase their strength and stability.
2. Root Canal Therapy: Many years ago, if your tooth was infected or damaged it would need to be removed. In the 21st century, your dentist has special techniques to save your natural teeth instead of extracting them.
While tooth enamel is stronger than bone, it’s not indestructible: There are oral bacteria that live in your mouth and feed off mostly sugar and food particles. After these bacteria chow down, they produce acids that erode the enamel slowly. Over time, the acid will form a hole called a cavity and those bacteria will invade and inflame the soft pulp and roots inside causing discomfort and pain. Regular brushing and flossing remove the bad bacteria and reduces the risk of cavities.
To save the tooth, the dentist drills a hole through the crown (remember: the bacteria made one hole, the one the dentist made which is called an access cavity). Then he or she uses what’s called an endodontic file to remove the infected pulp and clear the canals. To prevent re-infection, the root canals are filled with a sterile material (called gutta-percha). To close the hole, strengthen the tooth, and prevent another infection, a crown will be cemented over the restored tooth.
3. Cracked or Fractured Tooth: Human teeth are very strong and meant to last your entire life. The body naturally helps maintain your teeth with saliva. Saliva prevents the build-up of cavity-forming bacteria by washing them away and keeps the mouth less acidic so the teeth can naturally re-mineralize themselves with calcium. But sometimes non-cavity damage can be so severe that only a dentist can repair your tooth.
Cracked tooth syndrome is exactly what is sound like; the outer enamel of the tooth is broken or fractured. This can be caused by anything that places excessive stress on your teeth. Some common causes of cracked teeth are:
• Using your teeth as tools, e.g., opening bottles or packages.
• Chewing on ice cubes and inanimate objects.
• Getting struck in the mouth during an athletic competition.
• Bruxism, the unintentional clenching and grinding of the teeth when one is asleep or awake.
Cracks are more likely to form in the molars in the back of the mouth because those teeth can exert over 200 pounds of force when chewing.
You may have this condition if:
• You feel a “stinging” or a “zapping” sensation whenever you bite down.
• You feel pain when you eat or drink something that is either hot or cold.
When the outer enamel shell of your tooth is cracked, chewing causes the part to move. This movement irritates the tender pulp which causes you pain. Cracks are almost impossible to diagnose with X-rays since they usually very tiny. Your dentist may try one of the following ways:
• He or she may stain the tooth with a special non-toxic dye.
• He or she may illuminate the tooth with a special light that will expose any imperfections.
• He or she will ask you to bite down with each individual tooth on a special tool. He will find the crack when you report which tooth hurts when you bite.
A cracked tooth can generally be restored as long as the crack does not extend down to the root and/or go below the gum line. If the crack is deeper than the gums, then the tooth will need to be extracted and replaced with an implant. But when the crack is shallow your dentist will place a crown over it to protect the breach from bacterial invasion and to improve its overall shape.
What is the Process of Getting a Dental Crown Like?
From start to finish, a dental crown procedure will almost always take two visits. The first visit, which usually takes around 30 minutes to an hour, will consist of three steps and they are:
1. Preparing the tooth.
2. Taking an impression of the tooth.
3. Placing a temporary crown.
On the second visit, your dentist will install the finished crown with cement. This trip normally is done in about 20 to 30 minutes.
Let us talk more specifically about what your dentist is going to do on the first visit.
Tooth Preparation: While the term might sound strange, all “preparing” the tooth means is shaping it so the permanent crown will fit correctly. Tooth prep can be divided into the following steps:
1. Numbing the tooth: The dentist will want to numb, or anesthetize, the tooth and the gum tissue that envelopes it.
Before the injection, your dentist will apply a numbing agent, usually a gel, to the injection site so that you will not feel the prick of the needle as much. Then he will slowly insert the needle into the injection point and start depositing anesthetic. Then he will advance the needle a few millimeters and deposit more anesthetic. He will repeat this process until the entire injection site it totally numb. He does it this way to ensure the needle is only passing through numbed tissue which minimizes pain.
Also, it is best not to struggle or squirm since that will make it more difficult for him to direct the needle accurately and if he or she misses they will have to start all over again.
2. Shaping the Tooth: To be effective, there is a minimum thickness required of every crown. While it varies depending on the material (more on this later), most crowns need be at least 2 millimeters thick. When the tooth is prepped, the dentist is going to file away enough of your tooth material so that crown can fit without the risk of slipping.
Also if your tooth has any areas of decay the dentist will file these away to prevent them from spreading. If you have had a root canal, he or she may also remove the filling if it appears loose or otherwise unstable.
To shape the tooth, your dentist will use a cylindrical tool called a bur. This is a highly precise instrument that will help him or her to trim away just enough of your dental material for optimal crown placement.
In rare instances of severe tooth decay or a very bad fracture, there might not be enough tooth left on which a crown can be affixed. If the crown does not have enough tooth supporting it, then there is a huge chance that it will break off. To prevent this he or she will “build-up” your tooth with a core.
A core is a nothing more than permanent dental restoration material that is used to reconstruct a tooth close to its original proportions. The core is normally made of the resin that is used to make white cavity fillings or dental amalgam (the metal used in silver-colored cavity fillings). Even with a core, the dentist may still need to trim some of your natural teeth if the shape is not conducive to crown placement.
The core process could be divided into three steps:
I. *The dentist will drill down to one of the root canals (each tooth has one to five) to place a post. A post is a piece of metal that will anchor the core in place. If a post is not used, he or she may install a series of tiny pins to secure the core.
II. The post will make its new home in that root canal and be cemented into place.
III. The dental restoration material will be packed over the now-secure post and shaped into the core by your dentist (this is almost like how a sculptor will shape a mass of clay into a sculpture). When finished, the tooth will be about the same size as it was before it lost any material.
*A post is only used if the patient has undergone root canal therapy.
Taking an Impression: Now that the tooth is properly shaped, your dentist is going to take an impression of it to ensure its accuracy. He will use a tray or mold to do this. This mold is what will be used created your customized crown. This process is very simple and will only take about five minutes.
First, to make the area around the tooth dry, your doctor will use the suction tube and cotton rolls to remove excess saliva. Then he will inject impression material around the shaped tooth. For some patients, the gums will get in the way and can make an accurate impression impossible. To avoid this, your dentist will move the gums back slightly with a gingival retraction cord.
Third step: you will be asked to bite down on an impression tray and wait. After a few minutes, your dentist will take the tray away and send it to a lab*. Your new crown should be ready for you in about one to two weeks.
* Recently some dentist offices have been using what are called “crown milling machines”. With these machines, you could have the entire crown process completed in one visit.
Steps one and two of crown preparation will occur as normal. Then your dentist will take a special wand with a digital camera, called an intra-oral scanner, on its business end to take a 3-D photo of the shaped tooth and the neighboring ones. The picture is sent to the milling unit which will then grind down a tiny cube of porcelain into a crown based on your photo.
Your dentist can customize this photo before the crown is fabricated. The unit can only make porcelain crowns (we will get to the material used for crowns later) and your dentist might not feel that that is the best material for you based on your dental history.
Temporary Crown: Most dentists will send your impressions to a lab where your crown is handcrafted by a specialist called a ceramist. This process takes about two weeks. Obviously, you need to eat and drink in the meanwhile so what are you to do to protect your tooth? There is no need to worry; your dentist has you, and your tooth, covered…literally!
At the end of this first visit, your doctor will give you a temporary crown. Like a regular crown, this is mean to protect your tooth and make it easy for you to bite food. Your dentist will custom-make your temporary in the office while you wait. It probably will not match the color of your other, natural teeth perfectly. Once installed, do not chew anything for at least thirty minutes so the cement can solidify.
You will probably notice some sensitivity around the crowned tooth, especially after have eaten or drunken something that is either hot or cold. That is perfectly normal and this will go away once the permanent crown is fixed. Also take care not to brush and floss too hard around the temporary crown or you may weaken the cement and cause it to fall out. If your temporary crown ever comes out, call your dentist immediately so he or she can re-cement it for you.
Here are some tips to help you care for your temporary crown:
1. Just like regular teeth, some foods you eat will stick to it. The cement on your temporary allows your dentist to easily remove it when your crown is ready. But sometimes sticky foods can pull it out of place too. Avoid foods like taffy, chewing or bubble gum, and caramel.
2. While you are at it, avoid hard foods like ice cubes, apples, carrots, and hard candies which could break and/or dislodge the temporary.
3. Your best bet when eating is to avoid using that side of your mouth where the temporary is much as possible.
4. Be very careful when you floss! Instead of sliding it up and down between your teeth, slowly move it out to the side by letting go of one end of the floss.
5. Rinse your mouth with salt water 3 times daily. Mix one tablespoon of table salt with 8 ounces of water. This reduces sensitivity along the gum line.
6. If you do not have one already, get and use a soft bristle toothbrush to reduce the risk of swelling and irritation (the tooth preparation process will slightly agitate your nearby gums).
Even if you take all the temporary crown care precautions listed above there is still a chance that it might fall out. If it is very loose and/or falls out, call your dentist immediately to have it re-cemented! This is very important: Even in just an hour or two, the teeth near the prepared tooth can shift which means your finished crown will not fit properly. Then you will need to spend more time in the chair getting another impression done.
If you cannot get to the office to get it replaced the same day then buy a tube of over the counter dental adhesive such as Recapit or Dentemp. All you do is apply some of the adhesives to the base of the crown and place it back over the tooth. DO NOT USE ORDINARY HOUSEHOLD OR CRAFT PROJECT GLUE! THOSE PRODUCTS COULD BE TOXIC.
Let us fast forward two weeks to the second dentist appointment. This visit can be divided into 3 of steps:
1. Temporary Crown Removal: Your dentist will remove the temporary crown. After that, he or she will also remove any residual cement from your tooth as well.
2. Evaluate the Crown: Next he or she will, place, or seat, the crown on the tooth. He will ask you to bite down and visually inspect how the crown touches against neighboring teeth. He may reseat the crown several times until he is satisfied with it.
If you do not like the color or the fit does not feel comfortable, then tell you dentist: After the crown is cemented it is very difficult to remove it.
3. Cementing Your Crown: After having adjusted the crown for fit, the dentist will cement it into place. First, he will place a layer of cement in the crown and re-seat it on your tooth. Once seated, the dentist will remove any excess cement from the sides. And now you have a brand new crown!
The Process of Getting a Dental Crown in a day: Cerec Crown in one visit
How Long Will My New Crown Going to Last?
There is not a definitive answer to this question. Just to recap, the dental implant that we call a crown is typically made of several parts:
1. Crown: The ceramic or metal (more on crown material in the next section) cap that covers the tooth.
2. Post: The metal implant that acts as the “root” of the crown and keeps it in place.
3. *Core: The artificial restoration made from dental resin.
Since the crown is exposed and will be absorbing the stress of your chewing food it is most likely of the three parts listed above that is going to break.
But the answer to the question above is: It depends. Generally speaking, dentists expect their crowns to last from 5 to 15 years on average. Anything less than 5 years would probably make your dentist feel bad. Most insurance companies are willing to pay for a replacement crown as long the original lasted a minimum of five years.
A crown could easily be made to last indefinitely if you maintain good oral hygiene habits by brushing twice a day, flossing at least once daily and have 2 routine dental check-ups annually.
Another factor affecting the longevity of a crown is its location. A crown in the front of your mouth will last longer than one in the back of your mouth (a molar, bicuspid or wisdom tooth). This is because the teeth in the back of the mouth, where your jaw muscles are, can exert upwards of 275 pounds of force when you are chewing on something. More chewing power means more stress on those particular teeth. Also, people who habitually grind their teeth are more likely to break their crowns than those who do not.
A crown is not enameled so it cannot decay. Unlike dentures, it is permanently fixed to your mouth. The tooth structure underneath it can decay if you do not brush and floss regularly, though. Bad oral hygiene is a leading factor conducive to the development of the gum disease gingivitis. Gingivitis could cause gum line recession that can lead to crown failure and necessitate subsequent replacement.
In theory, just like your natural teeth, a crown should last your lifetime depending on your oral health and its location. A study completed in 2013 showed that out of 2,430 patients 85% of their crowns lasted at least 25 years.
What Are Crowns Made Out of?
Generally, there are four different types of materials that are used to make dental crowns. All of them are very durable and will protect your tooth from further damage or decay but all have unique advantages and disadvantages. Your dentist will ask you which you on prefer. Let us look at the different types of crown in depth:
1. All metal crowns: These are dental restorations that are made either from gold, an alloy, or mixture of gold and other metals (like copper) or a base-metal alloy with no gold.
The biggest advantage to a gold or metal alloy crown lies in their durability. These crowns are considerably stronger than your natural enamel and can withstand chewing, bruxism, and other types of everyday stress that would break or chip a normal tooth. Due to their strength, your dentist will not have to shave off much of your healthy tooth structure to seat one.
The biggest disadvantage to a metal crown is the color. A lot of people do not like the look of a shiny gold or silver tooth in their mouth. Due to color issue, most people prefer to have these crowns seated on molar where they cannot be seen easily. But another overlooked factor to consider is that metals are efficient conductors of heat so warm or very cold foods or beverages could be uncomfortable.
2. All Porcelain a.k.a an All-Ceramic: An all-porcelain crown’s color will most closely match your natural tooth color than another type on this list. These are also a good choice for people who have metal allergies and therefore cannot get gold or alloy crown. These tend to be a very good choice from front tooth crowns.
Ceramic crowns are not are as strong as metal and as such are more prone to chipping and completely breaking. Ceramics tendency to breaks comes from the fact that it is very brittle. Another downside to porcelain is that while highly resilient; if the surface wears and becomes rough it can actually accelerate wear of the surface of neighboring teeth. If the crown gets stained a whitening solution will not work on it.
Also, it is important to remember that not all all-porcelain crowns are made equal! The off-white crowns from a milling machine are porcelain. On the other hand, the crowns that are made by a ceramist could be combined with multiple layers of porcelain to ensure maximum durability and color congruency.
3. Porcelain Fused to Metal: This is a combination of types 1 and 2: It is a porcelain crown that encapsulates a metal structure that provides the strength of type 1 with desired natural look of type 2. They can be used anywhere in the mouth. They have been used since 1950’s and have become a favorite of dentists and patients alike.
Generally, these crowns appear to be just a durable as all-metal crowns. Due to their metal nature, they can make your tooth more sensitive to temperature changes caused by food and drink just like all metals. Also if the porcelain surface is not properly glazed, that is given a glassy coating in high-temperature kiln or oven, it may have rough edges that will cause the enamel on abutting teeth to wear away.
A unique, but a totally harmless problem that is unique to porcelain fused to metal crown is that they sometimes develop a dark line near the base. The dark line is nothing more than the metal showing and does not mean your crown is in any way defective. If you do not like the way it looks then you can ask your dentist to replace it for you.
4. Zirconia & Porcelain Fused to Zirconia: Lately patients have been demanding a wider selection of crown options because:
I. They want a strong restoration that will last a lifetime while blending in with their natural teeth.
II. Some do not feel comfortable with the idea of a having a piece of metal in their mouths 24/7.
So to this end, dentists have started using zirconia for crowns around a decade ago. Zirconia crowns are stronger than porcelain, which has a tendency to chip, and their translucent color let them blend in easily with your natural teeth, unlike metal crowns.
Also, zirconia is popular for its biocompatibility, which means that it is not known to cause allergic reactions in humans like other metals do for some people. Even though it is durable, zirconia is malleable, or flexible, so your dentist can easily have it shaped to your tooth with minimal, if any, shaving/preparation required.
Zirconia fused to porcelain crowns are crowns that have a layer of porcelain covering a zirconium structure. This combination gives you all the strength benefits of zirconium with the naturalistic appearance of porcelain.
The only downside to a zirconium crown is its durability: It can be abrasive and could cause neighboring teeth to wear if the fit is not 100% accurate.
Ultimately there is no one right type of crown to pick. Each one has its distinct advantages and drawbacks. To get a sense of the best type of crown for you, think about your individual needs and talk to your dentist to get his input as well.
What is an Onlay? What is a 3/4 Crown? How Are These Different From Crowns?
To understand what these are we need to understand some general tooth anatomy. Every tooth that is not an incisor has cusps on it. Cusps are the raised points on a tooth. Cuspids have 1 cusp, bicuspids have two, and your molars have the most cusps (either 4 or 5).
An onlay is a restorative procedure that is used to replace just one cusp on a tooth. A crown is essentially an onlay that covers the entire tooth surface instead of just a fraction of it. Your dentist will recommend an onlay if your tooth is too weak for a filling but not damaged enough for a full crown. Shaving down and capping a tooth unnecessarily will leave it prone to breakage and would then might require a root canal to fix.
A 3/4 crown is an onlay that covers 3 of the four sides of your tooth surface.
When deciding between a crown, an onlay, and 3/4 crown you should consider the location of the affected tooth. Onlays and 3/4 crowns work best on teeth with large surface areas like molars and bicuspids. All three of these procedures have nearly the same price.
So I Have Picked My Crown and Had It Installed…Does it Need Any Special Care?
Generally speaking, a crown tooth requires the same care as your regular, natural teeth do: You need to brush at least two times per day, floss at least once daily and see your dentist for routine cleanings and check-ups twice a year. Brushing massages the gums and removes food and sticky plaque deposits just like how a broom sweeps up dirt and dust. Flossing removes plaque and tartar below the gum line where your toothbrush cannot reach.
Remember that a crown is not a replacement for the tooth but rather just a covering for part of your existing tooth structure which means that there is always the risk that you could develop tooth decay under the crown.
The best thing to do is to treat your crowned teeth as if they were your regular teeth. That means:
1. Do not use your teeth as tools.
2. Avoid biting down on hard objects such as ice cubes, pens, and unpopped popcorn kernels.
3. Wear a mouth guard or a facemask if you participate in any contact sports.
4. If you suffer from grinding your teeth while you sleep, talk to you dentist about getting fitted for a night guard. A night guard is a like an athlete’s mouth guard that you wear while you sleep to stop you from excessively grinding your teeth.
How Much Do Dental Crowns Cost?
As we covered in an earlier section, the process to get a crown take place over two visits and consist of three steps on each visit. Just to quote the cost of the crown does not give you the full picture of the total cost of the procedure (you will be charged for each step, i.e, shaping the tooth is one charge, an impression is another, the temporary crown has a cost, as does its installation, etc). Not only that, but the cost of a crown procedure varies depending on the city and state you live in and will vary depending on your type of insurance coverage you have. Most insurance typically covers up to fifty percent of the procedure and some plans have annual maximum limits so you should find out exactly how much your plan will cover (if you exceed it you must pay the overage out of pocket). Alternatively, you can have your dentist send your insurer a pretreatment authorization so you can find out how much, if anything, you would be responsible for paying on your own.
The numbers listed below are just general guidelines and are subject to change at any time:
• Porcelain Fused to Metal: Average price is around $1000 USD but they range from $500 to upwards of $1500. If you are uninsured one will set you back about $1100.
• Metal (Gold, Alloy, or Gold Alloy): Average price is around $900 with insurance. The price range goes from $750 at the low-end all the way up to $2400(the more gold in the crown the higher the price). Without insurance, the cost should be around $1400.
• All Porcelain: The most expensive material. Prices normally range from $1000 up to $3000. With insurance, the average cost would be about $1000. An uninsured person should be expecting to pay about $1600 out of pocket.
What Are Some Common Problems That People With Crowns Have?
A crown is a restorative procedure that will help your tooth maintain its strength and structure. While it is designed to be a long-term solution for teeth that have been damaged by physical trauma or tooth decay, it is not a permanent solution.
Here is a list of common problems that people with crowns sometimes encounter:
1. The crown falls off: This is the biggest problem by far. This happens for one of the following reasons:
a. The core broke off: Look in your crown. If you see some sort of a material along with parts of the tooth in it then the core failed. The core was there because there was not enough tooth material to attach the crown to. This is very difficult to fix and you will need to have the tooth extracted or get a root canal so you can get a post crown implanted.
b. The post failed: Look in your crown. Do you see a tiny metal rod in it? If so then the post has come out. This can be caused by weak cement, the post being too short, or if the root is fractured. The first two reasons can be fixed easily (with better cement or longer post, respectively) but a fractured root can hold an additional post and the tooth will need to be extracted.
c. The cement failed: Look in your crown. Does it look hollow? Now look in your mouth. Do you see a stump where the crown was? If you answered “Yes.”, to both then you just need some new cement for the crown. When you go to your dentist, ideally on the same day, he or she will also check to see if there was any tooth decay that caused the crown to fall out.
2. The crown breaks: This problem is almost exclusive to all porcelain crowns but can also occur to porcelain fused to metal crowns. Just like cracked tooth syndrome, this is usually caused by eating very hard foods or chewing on non-food objects.
The best way to fix this is to get a new crown seated, preferably one that made of a more durable material. If the patient does not want a new one then the dentist can try to repair the cracks by plugging them with a composite filling. It is better to get a new crown since the filling with eventually sometime down the line.
3. Sensitivity: If you notice mild pain or discomfort from hot and cold foods and drinks or when your breathe through your mouth, you have what dentists refer to as thermal sensitivity. You likely have sensitivity if the pain is only caused by the same stimuli and does not get worse over time.
When your tooth is prepared some of the outer enamel shell is ground away. If too much enamel was filed off, the dentin beneath it will be exposed. This can be easily cured by using a toothpaste that states it is for sensitive teeth.