Crowns

 

What are dental crowns?

         Crowns are a type of dental restoration which, when cemented into place, fully cup over the portion of a tooth which lies at and above the gum line. In comparison, fillings are dental restorations that are used to fill in or cover over just a portion of a tooth. Since dental crowns encase the entire visible aspect of a tooth, a dental crown in effect becomes the tooth's new outer surface.
Crowns can be made out of porcelain (or some other ceramic material), gold (or metal alloys), or a combination of both. Dental crowns are often referred to as "dental caps" or "tooth caps".

Why do teeth need dental crowns?

    A dentist might recommend placing a dental crown for a variety of reasons but, in general, most of these reasons will usually fall within one of the following basic categories:

                    --To restore a tooth to its original shape.
                    --To strengthen a tooth

                    --To strengthen a tooth.

How are dental crowns used to restore a tooth's shape?

      Since a dental crown cemented into place essentially becomes the new outer surface of the tooth it is easy to imagine how the placement of a crown can restore a tooth to its original shape. Dental crowns are often made for teeth that have worn excessively, have broken, or else have had large portions destroyed by tooth decay.
     Conceivably the placement of a dental filling could, as an alternative, be used as a means to restore a tooth's shape. Dental crowns however offer a big advantage to your dentist over dental fillings by way of the fact that they are fabricated "away from your mouth". By this we simply mean that dental crowns are fabricated in a dental laboratory (by a dental technician who uses plaster molds your teeth made by your dentist). Dental fillings, in comparison, are created "in your mouth" by way of your dentist placing the filling material directly upon your tooth.
     When a dental crown is made the dental laboratory technician can visualize and examine all aspects of your bite and jaw movements, from a variety of angles, and sculpt your dental crown so it has the perfect anatomy. In some cases this anatomy will be even more ideal than your tooth's original shape. When placing a dental filling a dentist has less control over the final outcome of the shape of your tooth because it is often difficult for them to visualize, evaluate, and access to the tooth on which they are working.
                     How can dental crowns be used to improve the cosmetic appearance of teeth?

       Since dental crowns cup over teeth, any dental crown that has a porcelain surface can be used as a way to idealize the cosmetic appearance of a tooth. Possibly you have heard it said (especially in past decades) that such-and-such movie star has had their teeth "capped" (the term "cap" used here is equivalent to the term "dental crown"). This simply means that the person has obtained their "Hollywood smile" by way of having dental crowns placed.
      Actually, getting your teeth "capped" so just to improve their appearance can at times be a very poor choice. Dental crowns are best utilized as a way to improve the cosmetic appearance of a tooth when the crown simultaneously serves other purposes also, such as restoring a tooth to its original shape (repairing a broken tooth) or strengthening a tooth (covering over a tooth which has an excessively large filling).
      In general, dental crowns probably should not be used as a means to improve the appearance of a tooth if there is any other alternative dental treatment that could equally satisfactorily achieve the same cosmetic results. This is because a dentist must grind a significant portion of a tooth away when a dental crown is made. If a more conservative dental procedure could equally well improve the tooth's appearance, such as a porcelain veneer, dental bonding, or even just teeth whitening, then it is usually best to consider that treatment option first.

                          How do dental crowns strengthen teeth?
       The strengthening capability of dental crowns is related to the fact that they cup over and encase the tooth on which they are placed, thus serving as a splint which binds the tooth together. Dental crowns are a very important means by which a dentist can strengthen a tooth.
In contrast, dental fillings, especially large ones, often have a weakening effect on the teeth in which they are placed.            Dental fillings rely on a tooth's remaining structure to hold and support them. Fillings, in general, don't strengthen a tooth and don't protect a tooth from the forces generated by biting and chewing. If a small amount of tooth decay is present then it's usually no problem to make a repair by way of placing a dental filling. In these cases there will still be a substantial amount of healthy tooth structure remaining after the decay has been removed and the filling has been put in place. On the other hand, repairing a large cavity often requires removing so much tooth structure that the overall strength of the tooth is greatly reduced. This is simply because the tooth is no longer as intact as it once was, its structural integrity has been compromised.Of course it's not exactly the same thing but... the structural integrity aspect of a tooth is a little like an egg. If you take a raw egg and want to break it open, well it really takes a pretty firm rap. That's because an egg shell, in that specific shape, is really a surprisingly strong object. Now, in comparison, say you have broken the egg open and the two halves of the empty shell are lying on their sides. It's pretty simple to crush each piece of the shell now. Its structural integrity has been compromised. The shell is no longer in the shape it was meant to be so to withstand forces. Teeth are somewhat the same in the sense that once a large portion of the tooth is missing (because it has broken, decayed, or has been drilled away) it is simply no longer as sound.

What constitutes a big dental filling?

       Well of course this is the  question, and it's more or less what you are relying on your dentist to provide you with an opinion about. It's your dentist's obligation and responsibility to provide you with information, advice, and options on how best to restore your teeth.
       Really, any filling which is greater than about a third of the width of its tooth could be considered to be a filling large enough that the strength of the tooth overall has been reduced and the tooth is now a good candidate for the placement of a dental crown. Some dentists are even more conservative in their opinion and feel that if a filling is greater than about one third of the distance between a tooth's cusp tips, the tooth is significantly more prone to breakage.
      Take a look at the animation to the right. Each of the dental fillings shown could be considered to be "large". In each illustration an arrow(s) points to that portion(s) of the tooth which would be expected to be most prone to cracking or breaking off.

            What size are the dental fillings in your teeth?

       Possibly by now you have already been to the mirror so you can judge the size of the dental fillings in your teeth. Did you see any "large" ones? Now, ask yourself how long those big fillings have been in place. What was your answer?      Two years, five years, longer? So what's the deal? If teeth with big fillings are so weakened, why haven't parts of these teeth already fractured off?
    Of course the answer is that no dentist can know for certain which teeth will develop problems and which teeth won't.  No doubt if your dentist could see into the future they wouldn't be spending their time practicing dentistry. Dentists do have however, both from their dental training and clinical experience, an idea of which teeth are more at risk for breaking than others and they have an obligation to report this information to you.
     Clearly not every tooth with a "large" filling will break. Many people get many years of service out of these "large" restorations. Additionally, not every tooth that does crack or break will be especially problematic to repair. What your dentist is trying to relate to you however when they suggest the placement of a dental crown instead of a filling is that they believe a crown will produce the most predictable successful outcome for your tooth, in the long run.

       The relationship between dental crowns and root canal treatment.

    Some people seem to equate a tooth's need for a dental crown with the need for root canal treatment also. While both of these dental treatments may be required they are entirely separate procedures and, most certainly, not every tooth which has a dental crown placed on it needs root canal treatment.
   The relationship between dental crowns and root canal treatment is similar in nature to that between automobile bodywork (dental crown treatment) and under the hood work (root canal treatment). If you are in an accident (tooth breakage) you will need bodywork (the dental crown). If the accident has been especially severe and your radiator has been damaged, then you will need under the hood work also (root canal treatment), but it depends on the specific nature of the accident.

What are the consequences of not protecting a tooth with a dental crown?

It's impossible to know what the future holds for a tooth that seems to be a candidate for a dental crown, but here are some of the possible scenarios which might develop.

A) The tooth will experience no problems.

When a dentist suggests that a dental filling should not be placed but instead the tooth should have the protection of a dental crown they are no doubt basing their recommendation on their years of dental training and clinical experience.
As you might guess, some teeth that very much seem to be in need of the protection of a crown never become problematic. No dentist can know precisely what set of occurrences will transpire with a tooth. They are simply advising you as to what they consider to be the most predictable treatment in regards to the long-term health of your tooth.

B)The tooth will crack. One possible outcome for a tooth that is in need of the protection of a dental crown is that it will crack. Unlike cracks in bones, the cracks in teeth do not repair themselves or heal over. Once a crack has formed it often will, with time, increase in size due to the cumulative effects of repeated exposure to biting forces.
Those teeth which do crack can do so in the following fashions:

1) Teeth that have cracked but no piece has broken off or has become mobile. The tooth produces no pain or discomfort.

      In many cases unless a portion of your tooth has broken off you may not be aware that a crack has formed. This is because many cracks are difficult, if not impossible, to visualize and not all cracks in teeth are significant enough to produce symptoms. Probably the greatest threat associated with this status is that this condition may be the prelude to a more serious situation. While clearly not all cracks will unequivocally lead to problems, the presence of a crack can suggest that a fracture, cracked tooth symptoms, or a problem with the tooth's nerve may be more likely to develop with this tooth than if the crack was not present.

2)Teeth that have cracked and no piece has broken off or has become mobile. The tooth does produce some discomfort.

Cracked teeth can be sensitive. Biting pressure can separate the portions of the tooth associated with the crack and therefore trigger a painful response. 
The classic sign of a cracked tooth is that there is a sudden sharp pain from the tooth when you bite down. The pain then subsides once you have released your biting pressure. The pain may not be produced every time you close, sometimes it takes biting (or biting on something) at just the right angle to trigger the response.
While cracks in teeth do not heal, cracked tooth symptoms can subside. If you anticipate that you do have a tooth which has cracked you should let your dentist evaluate it and make a treatment recommendation. They may determine that your tooth requires little or no treatment, or at the other extreme, that a dental crown should be placed so to splint the tooth together.

3) Teeth which crack and as a result have a portion which breaks off or becomes mobile.

Teeth can crack and as a result have a piece that fractures off. The piece that has separated can break away cleanly or, if the fractured portion is still attached to the gums, the piece will be mobile yet stay in place somewhat.
As you might expect, the amount of pain or discomfort associated with a tooth that has broken can vary widely depending on the specifics of the situation. Sometimes these teeth:

  • are totally asymptomatic.

  • are sharp or rough and therefore irritating to the person's tongue or cheek.

  • have an increased sensitivity to hot and cold stimuli.

  • are painful to biting pressure.

  • are spontaneously painful.

         Here are some of the scenarios which often present themselves as a result of a tooth fracture:

a) The tooth breaks in a fashion that is easily repaired.

      It's not always a catastrophic event when a tooth breaks and, in fact, in most cases it usually it isn't. Any tooth that has broken should however be inspected by your dentist so they can make a treatment recommendation. A stitch in time really can save nine when it comes to teeth.
     It is conceivable that such a small portion of the tooth has fractured off that it only requires some minor smoothing. At the other extreme you may find that your dentist recommends the placement of a dental crown. Especially in those cases where a large portion of your tooth is missing, take the obvious suggestion that both your tooth and dentist are trying to give you, have the crown made.

b)The tooth breaks, but it requires other types of dental work before the dental crown can be made.

     More serious tooth fractures will require more involved dental treatment to repair them. The tooth fractures, periodontal surgery (gum surgery) is required. If that segment of the tooth that has broken off comprises a portion of the tooth's root, gum surgery (periodontal surgery) may be needed before a dental crown can be placed. This is because the edge of a dental crown cannot extend too far underneath the gum line or else it will impair the health of the gums around the tooth. The tooth fractures, root canal treatment is required. Deep tooth cracks and tooth breakage can damage or compromise the health of a tooth's nerve. In these cases your dentist cannot simply place a dental crown on the tooth. They must first perform root canal treatment so to remedy the problem with the tooth's nerve.

c)The tooth breaks in a fashion in which it cannot be repaired. Surprisingly, even teeth that have broken off flat with the gum line can usually be rebuilt. If a crack or break involves a large portion of the root portion of the tooth however (the portion way down underneath the gum line), your dentist may find that no dental treatment will be able to adequately repair the tooth and it must be extracted.

         What steps are involved when dental crowns are made?

It typically takes two separate appointments for a dentist to make a dental crown for a tooth.

A) Your dentist will numb your tooth.

Before the process of making your dental crown is begun your dentist will anesthetize (numb) your tooth and the gum tissue which lies around it.

B) Your dentist will shape your tooth.

So a dental crown has adequate strength and, in the case of porcelain type crowns, proper aesthetics, a crown must possess a certain minimal thickness. Your tooth in turn must be reduced by this same amount so once the crown is cemented into place your tooth will not be oversized. The minimal crown thickness that is usually needed lies on the order of about two millimeters or so, which is just a little more than a sixteenth of an inch.

In those areas where a portion of your tooth has already broken off your dentist may find that they have very little tooth reduction to accomplish. As a part of the trimming process your dentist will ensure that any and all decay has been removed from your tooth. 
Besides reducing your tooth so it is smaller in size your dentist must also shape your tooth in a specific fashion. A tooth receiving a dental crown must be slightly tapered in form so the crown will slip over and seat on the tooth.
The more tooth structure that extends up into the interior of a dental crown the more stable the crown will be. There can be times when so much of a tooth has broken off that a dentist will feel that they must first "build up" a tooth with filling material (make the tooth taller) before they do the final shaping for the crown.

C) Your dentist will make an impression of your tooth.

Once your tooth has been shaped appropriately your dentist will need to make a copy of it (termed taking an "impression"). Your dental crown then in turn will be made from this impression. There are two scenarios by which this process can occur:

1) Most dentists will take an impression by way of making a dental mold of your tooth using impression paste (a putty like material). This impression will then be sent to a dental laboratory that will in turn use it to create a plaster cast of your teeth. A dental technician will fabricate your crown so it fits accurately on the plaster cast. Since the cast is a precise representation of your teeth the crown will fit on your tooth also.
      Depending on the arrangements your dentist has made with the dental technician, the amount of time required to fabricate a dental crown is usually lies on the order of two weeks or so.
2) Your dentist might have a dental milling machine in their office. These machines are attached to a camera that can take an impression of your tooth optically. From this image the machine can subsequently design your dental crown and then create it by grinding down a block of dental ceramic ("porcelain"), all in a matter of some minutes. The obvious advantage of this technique is that a tooth can be shaped and its dental crown cemented into place, all in one visit.
      If your dentist does not utilize a milling machine it can be for good reason. Milling machines can only be used to fabricate all ceramic ("porcelain") crowns. Your dentist may feel that the physical properties and/or the aesthetics of this type of crown are not appropriate for your situation.

D) A temporary dental crown will be made for your tooth.

   In those cases where your dental crown will be created by a dental laboratory you will have to wait the two to three weeks while your crown is being fabricated. During this time period your tooth will be covered over by a temporary dental crown that your dentist has made. The temporary crown, which is typically made from plastic or else a thin shell of metal, will be cemented into place over your tooth.

E) Your dentist will select the proper shade of porcelain needed for your dental crown.

If your crown will have a porcelain surface your dentist will need to determine what shade of porcelain most closely matches your tooth's neighboring teeth. Usually a dentist will have a series of small tooth shaped pieces of dental porcelain (each of a different color) which are collectively called a "shade guide". Your dentist will select various porcelain samples from the shade guide and hold them in the area your new crown will occupy, until they find the one which most closely matches the color of your tooth's neighboring teeth.

II) Your second dental crown appointment.

  Cementing your permanent crown in place.

  At that point in time when the fabrication of your crown has been completed your dentist will proceed with the process of cementing it on your tooth. Your dentist will first make sure your tooth is numb. Then, if a temporary crown has been placed your dentist will remove it.
Before your dentist can cement your new dental crown into place they will first need to evaluate the way it fits on your tooth. To do so, your dentist will place the crown on your tooth, inspect its fit (possibly by way of using dental floss, feeling it with a dental tool, or asking you to gently bite down), remove the crown and adjust it, repeatedly, until they are satisfied. Especially in those cases where the dental crown will hold a prominent position in your smile, your dentist will also evaluate (and probably ask your opinion about) the crown's overall shape and color.
Once you and your dentist both agree that all seems right with your new crown it can be cemented. Your dentist will first place dental cement inside your crown and then seat it over your tooth. After a few moments your dentist will use a dental tool and scrape away any excess cement that has extruded from underneath the edges of your crown. The placement of the crown is now complete.

   What precautions should be taken with a temporary dental crown?

 Here are some things to know about temporary dental crowns, including some of the types of precautions dentists often recommend their patients take during that time when their temporary crown is in place.

 Temporary dental crowns are held in place by "temporary" cement.

Temporary dental crowns are usually cemented into place using "temporary" cement so they can be removed easily at the time of your next dental appointment. Because this cement is not as strong as other types of dental cement, your dentist will probably suggest that you take some precautions so not to dislodge your temporary crown. Some of the types of precautions your dentist might suggest are listed below. You will simply need to ask your dentist if any of these precautions (or any other precautions not listed here) are important and relevant to your specific situation.

 

Minimize the usage of the side that has the temporary crown.

         There's no need to look for trouble, give the temporary dental crown some consideration when eating. As much as possible, shift the bulk of your chewing activities to other areas.

Keep sticky foods away from the temporary dental crown.

Anything sticky (caramel, chewing gum, etc...) has the potential to grab onto the temporary crown and pull it off its tooth.

Avoid chewing hard foods with the temporary dental crown.

Chewing exceptionally hard foods, such as raw vegetables (carrots), can dislodge or break a temporary dental crown.

Suggestions related to brushing and flossing a temporary dental crown.

A tooth with a temporary dental crown can usually be brushed and flossed in normal fashion, with the following consideration. After flossing it may be best to remove the dental floss by way of letting go of one end and then pulling it out to the side. Pulling the floss back out in normal fashion might snag the temporary crown and pull it off its tooth.

             What to do if a temporary dental crown comes off.
      If your temporary dental crown does happen to come off contact your dentist's office so they can provide you with specific instructions and also make arrangements for you to come in and have it recemented.
In regards to that time period before you get back to your dentist's office to have the temporary crown recemented, your dentist might suggest that you simply place the temporary crown right back on your tooth. Doing so can protect the tooth somewhat from irritating stimuli such as hot or cold liquids. Wearing the temporary crown will also hold the tooth in place and keep it from shifting position (an important factor in how well or how easily your permanent dental crown can be fitted). Report to your dentist if you have found that the bite on your temporary crown seems incorrect when it is placed back on your tooth. In this situation your dentist will probably prefer that you leave the temporary crown off. If your uncemented temporary dental crown doesn't seem to stay in place very well your dentist might suggest that you fill it with toothpaste, vaseline, or else denture adhesive before you place it over your tooth (this technique should only be used for a few days). Of course your dentist will no doubt advise you that you will need to be careful with your temporary crown until it can be recemented. So you don't end up swallowing or biting on it unexpectedly, your dentist will probably state that your temporary crown should be removed when you sleep and eat. Anytime your temporary crown is not in your mouth you should keep it wet. Put it in a glass of water or close it up in a baggie containing a moist paper towel.

    Pain and discomfort while your temporary dental crown is in place.

If you notice any pain or discomfort with your tooth it's best that you let your dentist know so they can evaluate your symptoms. Here are some of the types of problems that can occur:

   A) The tooth has increased thermal sensitivity.

 It is fairly common that a person will notice some increased sensitivity to both hot and cold foods and beverages during that time during which their temporary dental crown is in place. This can often be related to the fact that the edges of the temporary dental crown cover over the tooth less fully and precisely than a permanent dental crown's edges will, thus providing a space by the gum line where these thermal irritants can get at your tooth. Just to play it safe however, in this situation go ahead and contact your dentist's office, report your symptoms, and let them make a determination.

  B) The gums around your tooth hurt.

It's not unusual that the gums around a tooth that has been prepared for a dental crown will be tender for a day or so. Since the edge of most crowns end at or below the gum line your dentist will have to perform dental work in this area. It is very easy for a person's gums to get roughed up during the crown making process. As a solution a dentist will often suggest that rinsing with warm salt water up to three times a day may speed up the healing of this gum tissue. However, in all cases, if something seems amiss you should feel free to report to your dentist and let them evaluate your situation.

   C) The bite on your temporary dental crown seems incorrect.

After your numbness wears off you may find that when you bite down your temporary crown touches first or hits harder than its neighboring teeth. In these instances your dentist will probably be very eager to adjust your temporary crown so your bite is more even. Don't expect this situation to take care of itself or improve with time. Allowing this condition to persist can seriously aggravate the tooth's nerve or even compromise its health.

  D) Discomfort with your tooth.

It is not out of the ordinary that a tooth might feel a little aggravated after having been drilled on. If you do notice discomfort go ahead and let your dentist know so they can evaluate your symptoms. As a solution for minor reversible conditions, a dentist will often suggest that their patients take an anti-inflammatory analgesic (such as ibuprofen or aspirin) so to help their tooth settle down. (You will need to read and evaluate the directions and precautions that accompany these products so that you know that their usage is appropriate for you.)

     What problems might be experienced with a permanent dental crown?

People can and do experience problems with those teeth on which a dental crown has been placed. No doubt it is both your and your dentist's hope that once your dental crown has been completed that your tooth will be just fine. Unfortunately, life sometimes runs contrary to our wishes.
Here are some of the types of complications people can experience, they can range from very minor and common place in nature to serious and disappointing. In all cases, if you experience a problem you should let your dentist know, sooner rather than later, so they can evaluate your symptoms and make a treatment recommendation.

  A) The tooth has sensitivity to both hot and cold stimuli.

 It's not uncommon that, after a dental crown has been cemented into place, a person will notice that their tooth has sensitivity to both hot and cold foods and beverages. Typically the location of this sensitivity is at the edge of the crown, by the gum line.
In some cases a dentist might have a very simple solution for this problem. The solution might be as easy as using a tube of one of those toothpastes marketed as being a treatment for "sensitive teeth" (the active ingredient in these products is usually potassium nitrate). However, rather than make an incorrect treatment decision yourself, let your dentist know you are having a problem so they can evaluate your situation and make a recommendation.

  B) The bite of the dental crown seems off.

Your dentist will have evaluated the way your dental crown touches against your other teeth when you bite down during that visit when they cemented your dental crown in place. Even so, you may find, especially after your numbness has worn off, that some aspect of your crown's shape is not quite right. Possibly when you bite down you feel your crowned tooth makes contact first, or maybe as you slide your teeth from side to side you can feel some aspect of the crown which seems too prominent.
This type of problem is usually an easy fix for your dentist, they simply need to buff your dental crown down so its shape is more in harmony with your bite. Don't expect this type of problem to take care of itself because it won't. In fact, if this condition is not remedied promptly it can lead to serious consequences related to the health of the nerve in your tooth.

  C) Other difficulties with dental crowns.

 The same events and circumstances that have led to the need for your dental crown (a broken or cracked tooth, a large cavity, etc...) can have a detrimental effect on other aspects of your tooth's health. Possibly your tooth was asymptomatic initially and now that the crowning process has been begun (or completed) problems seem to have popped up. While this set of circumstances is disappointing, it is not an indication that all was well with your tooth initially. It simply suggests that the full extent of the tooth's problems could not be identified beforehand.
Sometimes after dental crown treatment has been begun or completed a problem with the tooth's nerve becomes apparent and subsequently root canal treatment is needed. Some teeth are cracked seriously enough that even a crown cannot hold the tooth together sufficiently. These are not circumstances your dentist can predict with certainty, they can't see the future and know all outcomes. Your dentist is simply trying to rebuild your tooth in that fashion that their experience and training suggests to them is best and most reasonable.
If you have found that a problem has developed, or has persisted, after your dental crown has been placed simply report to your dentist, sooner rather than later, so they can evaluate your current situation and suggest a treatment solution.

   D) What to do if a dental crown comes off.

  If your dental crown comes off let your dentist's office know promptly so they can provide you with specific instructions and make an appointment for you where they will evaluate your situation and then, if possible (and it very often is), recement the crown on your tooth.
During that time which exists before your dental appointment your dentist may suggest that you simply place the crown back on your tooth. The idea here is that wearing the crown will protect your tooth from irritating stimuli such as hot or cold liquids. Placing the crown on your tooth will also keep the tooth from shifting. (A tooth without its crown can shift in position so much that a dentist will not be able to recement the crown but instead will have to make you a new one.)
Sometimes when a person places a dislodged crown back on their tooth they will find that the crown's bite seems to be off. This condition must be reported to their dentist so a revised recommendation can be made. Usually in this instance a dentist will feel that is best just to leave the crown off, but that is for them to decide.
If your dental crown doesn't seem to stay in place very well your dentist might suggest that you fill it with toothpaste, vaseline, or else denture adhesive before you place it over your tooth (this technique should only be used for a few days). Of course your dentist will probably also tell you you will need to be careful with your crown until it can be recemented. So you don't end up swallowing or biting on your crown unexpectedly, your dentist will probably suggest that you remove your temporary crown when you sleep and eat.

    What type of dental crown should you have made?

  Dental crowns can be made from metal, ceramic materials (porcelain), or a combination of both. The information on this page discusses the pros and cons of each of these various types of dental crowns, but in general you should rely on your dentist's judgment and advice as to which of these types of crowns would be most appropriate for your situation.

   All metal dental crowns. / Gold dental crowns.

 Some dental crowns are made entirely of metal. The classic metal dental crown is one made of gold, or more precisely gold alloy. Over the decades a variety of different metal alloys have been put to use in making dental crowns. Some of these metals are silver in color rather than yellow like gold.

Having a gold dental crown made can be an excellent choice. Here are some reasons why:

  1. Because of its physical characteristics dentists find gold to be a very workable metal and one which lends itself to their being able to achieve a very precise crown fit.

  2. Since they are metal through and through, gold crowns withstand biting and chewing forces well. They will not chip. It would be uncharacteristic for a gold crown to break. Of all of the types of dental crowns, gold crowns probably have the greatest potential for lasting the longest.

  3. Although they are very strong the wear rate of a gold crown is about the same as a person's own tooth enamel. This means that a gold dental crown won't promote excessive wearing of the teeth it opposes (the teeth with which it bites against).
    Metal dental crowns are usually placed on those teeth that are not overly visible when a person smiles (i.e. molars). If you are considering having a gold crown made take our advice on this point. Before you give your dentist the go ahead on making a gold crown, check with your spouse first. They're the one who will be looking at your smile and your new dental crown the most. Dental crowns that will show prominently when you smile are usually either made of porcelain or else have a veneer of porcelain on their surface, so that the crown's color is white like the rest of your teeth.

    All porcelain dental crowns.

    Some dental crowns are constructed in a manner where their full thickness is porcelain (or some other ceramic material). These crowns can possess a translucency that makes them the most cosmetically pleasing of all of the different types of dental crowns.
    Although they can be very life like in appearance, the overall strength of all porcelain dental crowns is less than the other types of crowns. While they can be a good choice for front teeth, due to the large chewing and biting forces which humans can generate an all porcelain dental crown may not be the best choice for back teeth.

    Porcelain fused to metal dental crowns.

     Porcelain fused to metal dental crowns are somewhat of a hybrid between all metal crowns and all porcelain crowns. When they are made the dental technician first makes a shell of metal that fits precisely over the tooth. A veneer of porcelain is then fused over this metal, giving the crown a white tooth-like appearance. Depending on the requirements of your situation, these crowns are sometimes made where the porcelain veneer only covers those aspects of the crown that are readily visible (the other portions of the crown have a metal surface), in other cases these crowns are pretty much fully surfaced by porcelain.
    Porcelain fused to metal dental crowns can be a good choice for either front or back teeth. These crowns are strong enough to withstand heavy biting pressures and at the same time can have an excellent cosmetic appearance. There are some disadvantages associated with porcelain fused to metal crowns however (which no doubt your dentist will try to minimize as much as is possible). They are:

  1. While the cosmetic appearance of these crowns can be excellent, they often are not as pleasing aesthetically as all porcelain dental crowns.

  2. The crown's porcelain can chip or break off.

  3. The porcelain surface of the crown can significantly wear those teeth that bite against it.

  4. The metal underlying the crown's porcelain can sometimes be visualized as a dark line found right at the crown's edge. A dentist will usually try to position this dark edge just underneath the tooth's gum line but if a person's gums recede this dark line can show, thus spoiling the crown's appearance.

    How long do dental crowns last?

    It would be reasonable to expect that a dental crown could last between five and fifteen years. Most likely a crown which did only last five years would be somewhat of a disappointment to your dentist. It's probably their hope that any crown they make for you will last ten years or longer. Depending on what wear and tear the dental crown is exposed to, and how well you keep the tooth to which it is cemented free of dental plaque, a crown can last somewhat indefinitely. Especially one found in a location where its cosmetic appearance is not much of a concern.

    Why do dental crowns need to be replaced?

    There can be a variety of reasons why a dental crown might need to be replaced. Some of them are:

     The formation of tooth decay.

     While a dental crown cannot decay the tooth on which the crown is cemented certainly can. If dental plaque is allowed to accumulate on a tooth in the region where the crown and tooth meet, a cavity can start.

    While there can be a lot of variables with this type of situation, the worst case scenario for your dental crown is that in order for your dentist to be able to get at the decay, and subsequently restore your tooth properly, the crown will need to be removed and replaced with a new one.

    B) The dental crown becomes excessively worn.

    Dental restorations are not necessarily more wear resistant than your own natural teeth, nor is it in your best interest that they should be. The ideal dental crown would be one made out of a material which has the same wear characteristics as your own teeth. This way neither the dental crown nor your teeth would wear each other excessively.
    Dental crowns can wear out, especially in those cases where a person clenches and grinds their teeth excessively. A dentist will sometimes detect a small hole on the chewing surface of a dental crown in that area where it makes contact with an opposing tooth (meaning a tooth which touches on the crown when you bite). In these cases, since the crown no longer seals over your tooth your dentist will probably recommend that a new crown be made, before that point in time when dental plaque has seeped under the crown and has been able to start a cavity.

    C) The dental crown has broken.

    Dental crowns can break, or more precisely the porcelain component of a dental crown can fracture. Some dental crowns are made in a fashion where their full thickness is porcelain. In these cases if the crown breaks it will most likely break through and through. Even if the broken piece of the crown doesn't come off either the esthetics, function, or the seal of the crown will most likely have been compromised and the crown will need to be replaced.
    Other ceramic dental crowns are of the "porcelain fused to metal" variety. When this type of crown is fabricated the dental technician first makes a thin metal shell that fully covers over the tooth, a layer of porcelain is then fused to this metal so to give the crown a tooth-like color. In cases where this type of crown has broken it is the layer of porcelain that has fractured off, usually revealing the metal tooth covering underneath (which is often grey in appearance). While the function and esthetics of the crown may have been compromised, the crown's seal over the tooth may not have been affected.
    Since the seriousness of a dental crown fracture can vary greatly, any crown which has broken should be evaluated by your dentist. Some minor damage might not be of much concern, and possibly ameliorated by a little smoothing with a dental drill, but only your dentist should determine this and only after they have had an opportunity to examine your precise situation.

    D) The esthetics of the crown have become objectionable.

    Some dental crowns are replaced because, from a cosmetic standpoint, their appearance is no longer pleasing. Two situations where the cosmetic aspects of a dental crown can change with time are:

    1) The dental crown's edge has become visible.

     Often as time passes the gum line of a tooth on which a dental crown has been placed will recede. This is especially likely in those cases where diligent brushing and flossing have not been practiced. If enough recession occurs the edge of the dental crown, which was originally tucked out of sight just under the gum line, will become visible.
    Inherent to porcelain fused to metal dental crowns (related to their construction) is the fact that the very edge of these crowns will show some darkness (a hint of the metal that lies underneath the porcelain). If enough gum recession occurs this dark edge will become visible, thus spoiling the cosmetic appearance of the crown.
    All porcelain dental crowns do not have the same inherent edge darkness as porcelain fused to metal crowns. Gum recession can, however, expose the portion of the tooth that lies beyond the edge of the crown (the tooth's root surface). Usually the color of this part of the tooth is significantly darker than the color of the dental crown, thus spoiling the cosmetic appearance of the tooth.

    2) The color of the dental crown no longer matches its neighboring teeth.

     Also related to the cosmetic appearance of a dental crown, there can be times when, as years have elapsed, the color of the crown no longer closely matches the shade of its neighboring teeth. In these cases it is not the color of the porcelain used to make the dental crown that has changed but instead the neighboring teeth have stained and darkened.
    There can be two solutions to this situation. The dental crown can be replaced with a new one that more closely matches the current color of its neighboring teeth. Another solution might be to use a teeth whitening process to return the neighboring teeth closer to the color they were when the dental crown was originally placed.

    Alternatives to having a dental crown made for a tooth
    There is no other dental restoration that covers over a tooth in the same fashion that a dental crown does *, and for that reason there really is no perfectly equivalent alternative treatment to the placement of a crown. There are however, depending on your specific circumstances, other choices that might be made. Since none of them are precisely identical to the placement of a dental crown you may run some risk when choosing one of them. It is your dentist's obligation to provide you with an intelligent discussion regarding all of the various options that dentistry has to offer.
    *There are variations on the technique of dental crowns, they are termed onlays and 3/4 crowns. The premise behind these types of dental restorations is identical to that of a crown, they just cover over a tooth less fully. For the purposes of our discussion here, we have considered these restorations to be the same as a dental crown.

    Alternatives to the placement of dental crowns.

    Here are some of the types of options that might be suitable alternatives to the immediate placement of a dental crown. It would seem that any thorough discussion your dentist provides would need to include most of these topics.
           You should never make a treatment decision unilaterally. Both you and your dentist together need to determine which of these alternatives might be a suitable approach for your specific situation.

    A) Delay the placement of the dental crown.

    This can be an appropriate solution in some circumstances, in other situations it could be the absolute worst decision. You should never elect this option without the advice and concurring opinion of your dentist. Especially in those cases where decay is already present, or the tooth has broken in a fashion where it traps food and plaque and decay is likely to form easily, delaying dental treatment could very well lead to more serious dental complications and even tooth loss.

    B) Seek another dentist's opinion.

    Different dentists have different skills and have had different clinical experiences. A second dentist may have varying views or insights regarding what they feel can be an appropriate treatment for your tooth. No one can predict the future, there isn't always one right solution to every problem. Hear each dentist out and see which approach makes the most sense to you.

    C) Ask what financial arrangements can be made.

    Dental crowns can be expensive and your dentist is probably asked about this possibility with some frequency. They may have a solution to offer.

    D) Temporize the tooth, delay the placement of the dental crown.

    This quite possibly could be a good solution. Once again, you will simply need to seek the advice of your dentist as related to your specific situation. Among the topics that need to be addressed are the time frame during which this temporization could be expected to be stable, and what precautions should be taken during this time period.

    E) Have a filling placed instead of a dental crown.

    While there can be a number of variables associated with this approach, having your dentist place a dental filling instead of a crown can be a solution. Sometimes this solution works exceedingly well. Having a filling placed now does not preclude the placement of a dental crown later. In fact, in most cases it would still be prudent to go ahead and have a crown placed on the tooth whenever circumstances permit.

    Especially in those situations where a large amount of your tooth is already missing or has been replaced by filling material, the circumstances related to placing a dental filling might be less than ideal. You cannot expect the filling your dentist creates to provide the same longevity or precise tooth restructuring that a dental crown can offer. As you have discovered on the other pages of this topic, dental fillings do not provide the same protection for teeth that dental crowns do. There is some risk in choosing the placement of a dental filling over a crown in that your tooth may break sometime in the future, possibly even irreparably.

    F) Have the tooth extracted.

     This seemingly simplest and cheapest of solutions can be worst and most expensive choice in the long run. When a tooth is extracted its neighboring teeth will have a tendency to shift, sometimes significantly. The resulting misalignment of your teeth can, in turn, have a major impact on your dental health. Even the removal of a single tooth can lead to problems related to your chewing ability, problems with your jaw joint, and predispose any teeth that have shifted to having problems.
    To avoid these complications your dentist will probably recommend to you that you replace the tooth that has been extracted. Replacing a tooth that has been extracted with an artificial one will most likely cost more than the alternative of not having a tooth extraction and instead rebuilding the tooth.

 
 
 

      Preparing The Tooth After A Crown--

    A crown is a tooth-shaped "cap" placed over a tooth that is badly damaged or decayed. A crown, which many people call a "cap," is made to look like your tooth.

     Crowns may be placed for several reasons, but generally the tooth has been extensively damaged by decay or breakage and filling material can't replace the missing tooth structure and make the tooth strong enough. A crown may hold together parts of a cracked tooth and can be used to hold a bridge in place. Crowns also are used for cosmetic purposes to cover misshapen or badly discolored teeth.

    Crowns can be prefabricated or made in a laboratory. Prefabricated crowns are made of acrylic or stainless steel and can be used as a temporary restoration until a permanent crown is manufactured. In some cases, prefabricated crowns can be used as a permanent restoration.

    Crowns can be all metal, porcelain fused to metal (PFM), or all ceramic. Metals include gold alloy, other alloys (palladium) or a base-metal alloy (nickel or chromium). The all-metal or PFM crowns are stronger and are better choices for back teeth. PFM and all-ceramic crowns look just like normal teeth.

    Crowns last at least seven years, but in many cases they last much longer, up to 40 years or so.

  

Preparing The Tooth

      If you need a crown, you may also need endodontic or root-canal treatment on the tooth, due to extensive decay or the risk of infection or injury to the tooth's pulp. Not everyone who needs a crown will also need a root canal.

     Besides the crown, your dentist may need to build up a foundation to support the crown. A foundation would be needed if large areas of the natural tooth structure were decayed, damaged or missing. If you are receiving the crown after root-canal treatment, your dentist may insert a post-and-core foundation.

     To place a crown, your dentist must file down the tooth to make room for it. If you are receiving an all-metal crown, less tooth structure will be removed because these crowns are thinner than PFM or all-porcelain ones.

      After filing down the tooth, your dentist will use a piece of thread or cord to push the gum down around the tooth, and then make an impression of the tooth. The impression material sets in five or six minutes and is removed. Your dentist will also take an impression of the teeth above or below the tooth that will receive the crown, to make sure the crown will not affect your bite.

     The impressions are sent to the lab, where the crown is made. During that time, you will have a temporary crown. These crowns are usually made of acrylic and are made in your dentist's office on the day of your visit. They are not meant to last. If a temporary crown is left in the mouth, the cement eventually washes out and the tooth can develop decay.

      At a second visit, your dentist will remove the temporary crown and test the permanent one. Sometimes crowns need additional polishing or glaze before they are placed. Once the crown is ready, it's cemented to your tooth.

 

  

            After A Crown

          You shouldn't feel any discomfort or sensitivity after a crown is placed, though if your tooth still has the nerve in it, you may have some hot/cold sensitivity. If you notice pain or sensitivity when you bite down, you should contact your dentist. Usually this means that the crown is too high on the tooth. This can be easily fixed.

         You may notice a dark line next to the gumline on your crowned tooth, particularly if you have a PFM crown. This dark line is the metal of the crown showing through and is normal. A crowned tooth is not protected from decay or gum disease. You should continue practicing good oral hygiene.

Crowns, especially all-porcelain ones, can chip. This can sometimes be repaired in the mouth. Your dentist will etch the porcelain with acid and bond composite resin to it to fix the chip. If the chipping is extensive, you may need a replacement crown.

It's also possible that the cement could wash out from under the crown, but the crown does not fall out. Under these conditions, bacteria can leak in and cause decay. If your crown seems loose, contact your dental office.

       Your crown may fall out, due to a lack of cement or an improper fit. If this happens, clean the crown and the tooth. You can replace the crown temporarily using denture adhesive or temporary cement sold for this purpose. Contact your dental office immediately and try to schedule a visit for the next day. If you are away from home, seek a dentist in the area who can evaluate the problem. You may need a new crown or it may be possible to re-cement the old one on the tooth.

Bridges

       A bridge is made to replace one or more missing teeth. Bridges can be supported by natural teeth, a combination of teeth and implants or just by implants. Traditional bridges involve creating a crown for the tooth or implant on either side of the space and cementing a false tooth between the crowns. When the crowns are placed, the false tooth (dentists call it a pontic) fills the space.

      If the teeth receiving the crowns are healthy and strong, they probably will not need root-canal therapy. However, parts of the teeth will be removed so the crowns will fit. Traditional bridges are either made of porcelain fused to metal (PFM) or ceramics.

          There are other types of bridges as well. Cantilever bridges are used when there are adjacent teeth on only one side of the missing tooth or teeth. A Maryland bonded bridge (also called a resin-bonded bridge or a Maryland bridge) consists of a metal framework with plastic teeth and gums. There are metal "wings" on each side that are bonded to your existing teeth. Bonded bridges are usually not as expensive as traditional bridges because the adjacent teeth need less preparation. However, these bridges are only as strong as the bonding material and do not hold up well in areas of the mouth where the biting forces are high.

         Getting a bridge requires at least two visits: the first to prepare the teeth to be crowned and make impressions, and the second to place the bridge. Bridges last at least five to seven years, and often longer.