Crowns and Bridges


Q: I’m 58 years old and nine or ten years ago I had a lot of bridgework done to replace a few missing top teeth.  I loved the dental work when it was done but I’m beginning to have some problems.  There is a gray line beginning to show around some of my gum lines.  Small pieces of porcelain have chipped away in a couple of places and my dentist says that I’m beginning to get some decay under the bridge.  Should I be having all these problems and what can I do about them?  V.R. in Wilmington

A: As I read your question I realized that you were speaking for many dental patients that I have heard from over the years.  Dentists and patients alike hope that our dental work will last forever.  Optimism can make us very unrealistic.  If you buy a new car you kind of know that after 5 years (when the warranty is finished) things are going to start to fall apart.  First it’s just a door ding.  Then the slurpee gets spilled in the back seat.  The first problems may just be wear and tear.  Dental work is not that much different.  First the hard pretzels and raw carrots begin to take their toll. You progress to hamburgers with an accidental piece of bone, chewing ice, or maybe you keep banging the porcelain crowns with your coffee cup.  I hope that you are beginning to get the picture.

One of the things that crosses my mind is that, unless you were in an accident, most people lose teeth because they didn’t take care of them well enough.  It is not unusual for patients to take care of their new teeth the same way they took care of their original teeth.  If a patient was susceptible to gum disease we can see continued receding gums.  This can create cosmetic as well as structural problems on the bridgework.  The dark metal line at your gum line is caused by receding gums.  The receding gums can also expose the roots of the teeth.  These root surfaces are softer and more likely to develop decay.  Sometimes the decay can be patched but after a couple of years even the patches fail and the bridgework needs to be redone.

Chipped porcelain is very difficult to fix.  The only proper way is to place it back in a porcelain oven.  Unfortunately, it is almost impossible to safely tap off old bridgework.  The bridgework or even the supporting teeth can be broken, beyond repair, while trying to remove the bridgework to repair it.

Of course, the better the bridgework was planned and constructed, the longer it will last.  Additionally, the better your home care, the less likely you will have receding gums and re-decay.  But under the best of circumstances all of us would rather have healthy, long lasting permanent teeth than an artificial replacement.

Q: I had a new crown placed 4 months ago and my tooth has been sensitive to cold ever since. Does the crown have to be redone? B.L. in Pike Creek

A: A crown is a porcelain and/or metal cover that strengthens and protects your tooth. Crowns (or caps) are usually done after a tooth has broken, had a lot of decay, or a root canal has been done. The crown restores the tooth to its original shape and size.

Without seeing your tooth it is difficult to answer the question, but the most common reason for your sensitivity is that the nerve inside your tooth is sick. Every time your tooth is irritated, broken, or drilled on the nerve in the tooth can also get irritated. Eventually this irritated nerve can get sick and begin to die. Sick nerves can be very sensitive. If your sensitivity is bad enough, a root canal is necessary. The root canal removes the nerve and the sensitivity will also be gone.

It is also possible that your crown is not fitting properly. Your dentist may need to do some adjustments to make your 'bite' more comfortable or even redo the crown if he discovers something that was missed when the crown was placed.

There are a number of other reasons that your tooth may be sensitive. They include receding gums, grinding your teeth, and even sinus problems. Your dentist should be able to correct the problem and make your tooth more comfortable.

Q: I recently broke a large piece off one of my back teeth. My dentist says that I need a crown on the tooth. Do I have any other options? G.L in Centerville

A: For those of you who are lucky enough not to have had one, a crown or 'cap' (same things) is a tooth shaped shell that fits on top of the broken tooth so that it looks and feels healthy and normal again.

To make a crown, your dentist first sands the tooth down to a 'peg' shape, then sends a mold of the peg shaped tooth, along with tooth coloring instructions, to a dental lab. The dental lab then makes a crown by hand specifically for you. The new crown is cemented in place a couple of weeks later and can be used and treated like any other tooth.

There are a number of options for putting the tooth back together again. These options depend on how badly the tooth is broken and the materials that your dentist and the dental labs are comfortable using. It may be possible to place a large filling back on the tooth, but remember, your last filling was smaller and the tooth was weak and it broke. There are a number of different types of 'lab made' partial crowns, called onlays. These 'onlays' only fill in the missing part of the tooth and can be made of composite, porcelain, or gold. Onlays are cemented or bonded into the missing parts of the tooth and can give it back the strength and shape that was lost. Onlays cannot be used in every instance and they can be more difficult to do.

Every dentist has procedures that they have found works best in certain instances and new procedures and materials are being developed all the time. Your dentist has recommended a time proven and effective treatment, however second opinions are always a good idea when you have doubts.

Q: I had a crown placed on a back tooth almost 3 months ago. It felt fine before the crown was placed, but now it is very sensitive to cold and I can't bite on it. What do you think is wrong? L.M. in Rehoboth

A: This is not an uncommon problem. A crown or cap (these are the same thing) is cemented over an existing tooth to restore its shape and strength. Generally speaking, crowns are not placed on completely healthy teeth. They are placed on teeth that have been broken, had lots of decay, or had many fillings.

It is possible that this new crown is the straw that broke the camels back. The process of preparing the tooth for a crown includes drilling on the tooth to remove cracks, old fillings, and decay. It is possible that the nerve inside the tooth became sick and now it is dying. It sounds as though you may have a 'root canal' problem brewing and you should be evaluated by your dentist.

Other possible problems include a poorly fitting crown, cracked roots, or an occlusion or bite that may need an adjustment.

Your dentist should be able to evaluate your problem and suggest the correct treatment.

Q: I recently went to my dentist and he told me that I need to have a crown with a post redone because there is decay under them. How did I get decay under my permanent crown? R.R. in Kennett Square

A: A crown (or cap) fits over a tooth that has been broken or decayed to give the tooth back its strength and shape. The damaged tooth is prepared first receive the crown. Crowns are then cemented on with permanent cement and can last for many years. The post, which is helping to hold the crown on, is a supporting rod that is used inside of weak teeth that have had root canals. Without the post, the crown would have very little to grab onto and the crown would fall off much more easily.

When you hear that there is decay under a crown or post, you definitely need to have them removed and redone. Of course the decay needs to be removed first. As for, "where did the decay come from?", you only have two choices. It was either left there from before the crown and post were done, or the decay is new. The longer the crown has been on, the more likely that the decay is new. But if you are not flossing, you can develop new decay in only a year or two. When a new crown is cemented in place, a seal is formed along the edges (or margins) of the crown where it meets the tooth. This seal is what prevents bacteria and food (and decay) from getting under the crown. The tighter a crown fits, the less cement is needed, and the longer a crown can last. Over time, with chewing pressure and fluids in the mouth, the cement margins around the edges of the crown start to dissolve away and bacteria can leak under the crown and cause decay. Unfortunately, this early leaking doesn't usually show up on x-rays. If you're lucky, the crown will fall off before there is any decay and it can be recemented.

I love it when a crown has been on for 10-15 years and a patient comes in complaining that they 'flossed it out'. Almost always it can be cleaned off and put back on. If there is decay under the crown it must be redone. So don't baby them. Floss them off.

Q: My removable bridge is 7 years old and it is getting loose. Does it need to be replaced? J.T. in Newport

A: A removable bridge or removable partial denture is a set of removable plastic or porcelain teeth held in your mouth by a thin metal framework that most often clips to some of your remaining strong teeth. Over time, as your mouth changes and the plastic teeth start to wear down, your 'partial' can get progressively looser. Sometimes, simply tightening the metal clasps can solve your problem. It would not surprise me to see that the shape of your mouth has changed and/or that the plastic teeth have worn down. If this is the case, your best option may be a new partial denture. Removable partial dentures can last from 5-15 years. You can imagine that a partial denture that replaces two teeth might last longer than a 'partial' that replaces ten teeth. Be sure to ask your dentist about other options to replace the missing teeth. Some of the other choices can allow you to have replacement teeth that do not have to be removed at night and will let you chew, speak, and smile as though you had your own teeth back again.

Q: I am 60 years old. About 15 years ago I had my missing upper teeth replaced with bridgework. The bridgework has looked great and given me no problems. However, at my last dental cleaning the dentist said that it all needs to be replaced because there is a little decay under one piece. New bridgework will cost me almost $10,000. Why can't my dentist remove the decay and let me keep the bridgework? G.J. in Newark

A: I don't know where to start, but $10,000 is a lot of money so we're going to get this right. First, a bridge is a replacement for a missing tooth or teeth. The teeth on either side of the space are crowned. A fake tooth (or teeth) is welded or fixed between the crowns. The result can be very strong, functional, and cosmetic replacement teeth. The bridgework is usually made of porcelain and metal and these materials will never decay. If the porcelain chips, it can sometimes be repaired, but the repair is weaker than the original porcelain. If the internal metal framework fractures, the bridge has failed and needs to be redone, but this is very unusual. Broken bridges are sometimes an indication of an occlusion or bite imbalance, but that's another article.

Bridges usually fail when the teeth they are cemented to fail. This failure can be from gum disease, tooth fracture, or most commonly from decay. Your problem seems to be bridge failure from decay. As the cement that holds your bridge in position starts to dissolve out from under the bridge, bacteria and then decay will begin to creep under the bridge. If the bridge is small, the dentist may be able to tap it off and repair it. But if it is larger and includes more than two support teeth, it is highly unlikely that the bridge can be removed without damaging the teeth or the bridge. In these cases, as in your case, the bridge probably needs to be replaced.

The trick for the dentist is to find the decay before the supporting tooth (with the decay) is completely destroyed and needs to be extracted. X-rays are not very helpful and if most of the bridge is firmly cemented, it may be impossible to find the decay under the 'loose' piece until it is too late. Sometimes a patient may complain of a bad taste coming from under a bridge. This can be an early sign of infection or decay. Unfortunately, for large bridges the result may be the same, because the bridge still needs to be removed.

So, how long should a bridge last? If the missing teeth were lost in an accident and you normally have had very little tooth decay, then a well made bridge can last 10, 15, or even 20 years. But if the original teeth were lost from decay and your re-decay rate is very high, and you never floss, you might be lucky to get five years.

It seems as though you have gotten good use from your old bridge and the decay was discovered early enough so that the bridge can be remade. It sounds as though everything is working just as it should.

Q: A friend of mine recently had all her front teeth capped. They certainly look better than they were, but I can tell they are fake. I also need crowns on my front teeth, but I am afraid they will look fake too. Do all crowns look artificial? H.R. in Centerville

A: All crowns are not created equal and serious cosmetics are not for beginners. Although you didn't elaborate, your friend's crowns are probably white and straight, but their color is opaque and lifeless, giving them a 'chiclet' look. You may also have seen gray gum discoloration above the teeth.

Many variables affect the esthetics and function (the chewing ability) of crowns. The two most important considerations are the skill of your dentist and his or her dental lab (or ceramist). Creating real-looking crowns is considered advanced cosmetics. To achieve such a skill level it takes experience and advanced training. A dentist with these skills will be able to recognize problems before they occur and deliver the look you want.

However, the skill of your dentist would be useless if he or she was using the wrong dental lab. Dentists are always receiving advertisements in the mail from dental labs that are offering less and less expensive crowns. The economics are pretty easy: the less money dentists pay for work done by a lab, the more money they can keep for themselves. Also, the less money labs receive, the less they pay the person that makes their crowns. Lab technicians, like all other professions, come in many experience and training levels. They can begin young and inexperienced and acquire skills with time, training, and the right equipment and facilities.

It sounds as though your friend had a ceramist (a person that makes porcelain crowns) that may have been technically good, but was not an artist. The more artistic and skilled a lab technician becomes, the more they charge for their crowns and the pickier they get about which dentists they will work with.

Ask your dentist for examples of his work. Many dentists take before and after photos for their records. Ask what type of training the dental office has had. There are a number of excellent training institutes for cosmetics. You will also find that the more experienced your dentist is in cosmetics the more likely they will know the name of their porcelain ceramist instead of just sending the work to a dental lab to be completed by anyone available.

With a little work I am sure that you will find a dentist (and a ceramist) that can give you the smile of your dreams.

Q: I had crowns done 7-8 years ago on my upper front teeth. I liked them when they were done, but now when I smile you can see a gray line at the edge of the gums. Can this be fixed? J.T. in Kennett Square

A: Generally speaking there are probably two main reasons for this dark line. The first is that you may be getting new decay around your crowns. If this is the case, then the crowns must be removed and replaced. Remember, you might have had the crowns placed originally because of decay, old large fillings, or chipped teeth. Although the crowns look nicer and are stronger, if you don't take better care of your teeth they will re-decay.

The second reason for the gray line is a little more mysterious. Over the past 7-8 years your 'gums' may have receded a little. This gum recession would have exposed more and more of the crowns. Around the edge of the crowns is usually a metal margin, almost like the 'white walls' on a tire. This metal edge, or margin, is supposed to be there. Unfortunately, it is very unsightly when it is visible. There is no good way to cover it up without possibly damaging the crowns or doing gum surgery.

The good news is that you do have a good, long-term option. Over the past 5-10 years new dental porcelains have been manufactured that are so strong that it isn't necessary to have a metal support, or coping, under the porcelain. The new crowns have no metal margins and the colors can be more translucent, pearly, and natural looking.

Talk to your dentist about these new porcelain crowns. It will be important to combine the skilled preparation and impression techniques of your dentist with the artistry of an expert dental lab to achieve your desired results.

Q: I had a crown done on my upper right back tooth about six months ago by my new dentist. It has been a little sensitive since it was put in, but has gotten progressively worse in the last couple of months. What do you think is wrong? L.S. in Hockessin

A: Without seeing you I am going to have to do a little guessing. One of the possible reasons for your sensitive tooth is a poorly fitting crown, but I am sure that you and your dentist have checked and found the fit to be correct. A more probable reason for your sensitivity is a sick nerve inside of your tooth. Remember (your tooth remembers) the reason that you have a crown on your tooth is that you have had previous decay, probably more than once. You have had deep and large fillings on this tooth, probably more than one, and/or you might have chipped or broken this tooth in the past. Something always must be the 'straw that broke the camels back'. The last time your tooth was 'worked on', the nerve inside of the tooth had finally had enough, and now it has begun to get sick and die. Removing the sick nerve, also called a root canal, can most likely solve the sensitivity problem. Fortunately, a root canal rarely damages the existing crown.


Damaged Teeth

Q: I have always worried that my teenager would break one of his front teeth. If this happens what should I do? J.H. West Chester

A: I recently saw a young boy that had badly chipped his two front teeth in a swimming pool. Fortunately, the moms that were watching him sought treatment quickly and brought the broken pieces of tooth with them. Additionally, the broken pieces were placed in a cup of milk. Most of us know that if a tooth is knocked out, it is important to get to a dentist within one hour.

Additionally, you should keep the tooth moist, either in milk or in a professionally prepared 'transport solution' that is available at most drug stores. But I am not sure if it is widely known that broken teeth can be put back together like the pieces of a puzzle if enough of the 'puzzle pieces' are available. Keeping those pieces of tooth moist can greatly increase the strength of the dental bonding agents (glue). Even exposed nerves can be saved if everyone moves quickly enough.

In short, if the tooth is broken or completely out do three things. First, find the tooth or pieces of tooth, then keep them moist. Finally, have the tooth re-implanted or put back together as soon as possible.

Q: I coach an 8-year-old soccer team. I would like to be prepared in case one of my players gets hit in the mouth. Do you have any suggestions? H.M.D. in Newark

A: It is unusual for soccer players to wear mouthguards, so injuries to teeth, although infrequent, are inevitable.

Cuts on the tongue, lips, and cheeks usually heal by themselves, but sometimes need stitches and should be looked at if wounds are open or bleed excessively. Additionally, a dirty cut needs to be cleansed properly, watched for infections, and might require an updated tetanus shot. Ice packs should be on hand and applied quickly. This will help to reduce swelling and can also reduce discomfort.

The more serious problems usually occur with the teeth. Teeth can be broken, displaced, or even knocked out (avulsed). In the event that any of these problems occur, it's important to see your dentist as quickly as possible. Teeth that are broken or avulsed should be treated within an hour of receiving the injury. Quick treatment is necessary because teeth that are replaced or repositioned during the first hour have a much greater chance of surviving. Be sure to keep the tooth or tooth pieces moist and as clean as possible. Rinse them gently with water and do not touch the tooth's root. It's preferable to keep the teeth moist by placing them in Hank's Balanced Salt Solution (H.B.S.S.) which can be purchased at most drug stores. Water or milk will also work if H.B.S.S. is unavailable.

To best prepare yourself for mouth-related injuries, I recommend that you have a dentist 'on-call', ice packs, H.B.S.S., and signed parent permission forms that allow medical treatment in their absence.

One last concern that may be beyond the scope of this column is broken and dislocated jaws. In most cases, as long as the child can correctly close his teeth together you are probably OK, but if you are unsure, then the child needs to be evaluated.

Because of the age of your players, we have been talking mainly about adult teeth. We, as dentists, are generally less aggressive about saving baby or primary teeth, but if you are unsure you can follow the same steps as for adult teeth and let your dentist make the decisions.

As a last resort, if you're unable to contact your dentist and time is running out, there's a terrific bunch of very well qualified, but very overworked, dental residents at the Christiana Care Medical Center. They are on-call through the Emergency Room and are available for true dental emergencies.

Q: I am 55 years old and recently my teeth seem to be chipping and cracking too frequently. I do have a lot of old silver fillings, and they are older, but I have never had this problem before. Do you know why this is happening? T.S. in Montchanin

A: You are either growing up and wearing out, like the rest of us, or you are doing something new and different to your teeth.

Teeth are made up of a couple of materials. There is a hard, enamel, crystalline shell with a softer inner dentin layer (kind of like M&M's). The more dentin (chocolate) that is missing, the more brittle and prone to chipping and fracture your tooth will be.

A number of things can create a lack of dentin or a weak tooth. The first, and most obvious, is decay. Decay starts on the outside of your tooth, but moves the fastest and causes the greatest problems when it gets into the dentin. The greater the decay, the more 'hollow' and weaker the tooth is. Silver fillings are another problem. While fillings are necessary to remove decay, the larger the filling, the more tooth (dentin) that is missing, and the more likely the tooth is to chip or break. There is a not-so-funny saying that "silver fillings grow up to be crowns." What this means is that through your lifetime, it is likely that your silver fillings will be replaced and increase in size until something breaks and you need a crown. Lastly, if your tooth has had a root canal, it is hollow. Hollow teeth are weak and root canal teeth have been really hollowed out. When a root canal tooth breaks, it can be a bad break that is difficult to fix.

Why have your teeth started to break now? You may have started grinding or clenching your teeth or changed your diet to raw carrots and hard pretzels. But if you aren't doing anything new, then your fillings and teeth are just showing their age.

Also, bear in mind that old silver fillings leak. They leak like the old caulk around your bathtub. Bacteria and fluids begin to fill in the space between your fillings and the tooth structure and you can get decay and weakening around and under the filling. After a while you may begin to have a bad taste and may have sweet or cold sensitivity. As a result, the tooth becomes weaker and may chip or crack.

The solutions to these old silver fillings are the bonded composite fillings, onlays (partial crowns), and crowns that replace the missing parts of the tooth and give it back its strength. There are times when these old fillings and chipped teeth can be fixed individually. However, there are other times when your teeth are severely worn down and the only proper treatment is a sophisticated and well thought out complete reconstruction. Your dentist should be able to give you the reasons that you are having these 'new' problems and also provide you with your treatment options.


Dentures

Q: I wear dentures. One dentist told me not to wear my dentures at night. Another told me to wear them all the time and not take them out. What should I do? M.G. in Talleyville

A: Both dentists were right, but for different reasons. I generally tell my patients to take their dentures out at night. I suggest to them that they would not leave their socks on 24 hours a day and that their 'gums' need to breath just like their toes. If you leave your dentures in all the time, you are much more likely to develop an infection under the dentures. However, I would be wrong not to tell you that my patients who leave their dentures in at night seem to have dentures that fit a little more securely and last a little longer. Unfortunately, this is probably because their 'gums' are a little swollen from being inflamed. If you have to leave them in at night, you need to at least be brushing the 'gums' that the dentures sit on, but taking them out at night is still the way to go.

Q: Even though there are lots of wonderful new techniques available, my wife and I have found that maintaining our teeth is too expensive. We are both thinking about having all our teeth removed and getting dentures.

A: For patients with no other options, dentures are wonderful. Unfortunately, I believe that dentures may be the 'evil that you don't know.' Regardless of the skill of the dentist, a small percentage of patients like their dentures so much that they wish that they had been born with them. However, another small percentage can't talk, eat, or even wear their dentures without discomfort and you will not know which group you belong to until it's too late to go back. Additionally, once your teeth are extracted, the bone that used to hold the teeth in begins to melt away and the dentures get looser and looser. Remember, there is a whole industry making denture creams and powders to make your loose dentures stick to your gums.

So, what do you do when saving all your teeth is too expensive and taking them all out is full of possible perils? My suggestion is to look into removable partial dentures. Partial dentures replace only the teeth that are missing. Start by removing the teeth that are weak or too expensive to keep, and if the remaining teeth are strong enough and in the correct position, you can use these teeth to support a new removable partial denture. Your dentist can go over the specifics with you. But remember, full dentures are not always the least expensive or the most appropriate treatment option.


Fillings

Q: I am 44 years old and ever since I can remember I have always had bad teeth. At every dental visit I always seem to have decay and all of my teeth have large fillings. It seems that I have wasted my time and my money. Do you have any suggestions? J.B. from Newark

A: I thought that I would start my answer with a question. Do you think that most dentists and dental office staff need fillings every time they get their teeth cleaned? I will tell you that the answer is no. In all fairness to you, there seems to be groups of people that are more prone to tooth decay. Certainly people who grew up and live in areas without flouride are more at risk. Also, conditions that cause your mouth to be dry, such as, using certain medications, seasonal allergies, and radiation therapy, to name a few, can greatly increase the amount of decay that you get. But I will also tell you that the most common reason that I see recurrent decay is poor (or inadequate) dental hygiene. The reason that dental office staff has generally less decay is that they understand how to prevent it and they 'live what they preach'.

I will give you a simplified yet effective way of visualizing the decay process. Bacteria that live on your teeth cause decay. If you feed these bacteria sugar they release acid that eats away at your teeth. Fortunately for us, the bacteria must organize on our teeth in order to do much damage. It takes almost 24 hours for the bacteria to organize, eat the sugar, and damage our teeth with acid. Every time you eat sugar (pasta, bread, fruit, soda, pretzels, juice, etc.), you feed the bacteria, and they can release acid for about 20 minutes. If you take a small sip of soda (or coffee w/ cream) every 15-20 minutes all day long, you are bathing your teeth in acid continuously and overwhelming your body's ability to keep away the decay. I would rather, for the sake of your teeth, that you drink a case of soda for breakfast, than sip on one can of soda all day long. I hope that I am making a case for decreasing the amount of time that you expose your teeth to sugar.

The next step in preventing decay is keeping the bacteria on your teeth from becoming organized enough to cause too much trouble. The question that comes to mind is how often should I brush and floss? Well, if it takes 24 hours for the bacteria to organize, then you should brush and floss once a day to prevent this 'organization.' Unfortunately, most of us don't do a perfect job of brushing and flossing. So it's a good idea to brush after meals and brush and floss before we go to bed. Remember, the bacteria like it best at night when it is dark and warm and moist for the longest period of time.

My staff and I have found that the people who generally get recurrent decay are our patients with the poorer eating and/or brushing and flossing habits. Many people that think they spend a lot of time on their teeth are usually having major problems in at least one of these two areas. If we can correct the cause of the recurrent decay, your fillings will last longer, and you will enjoy hearing that you don't have to return to the office for 6 months.

Q: Just recently I finished a series of dental appointments. I had lots of fillings done to get rid of decay. Now that I am done, can I get decay in the teeth that now have fillings? Z.G. in Wilmington

A: If you continue to do the things that led to decay in the first place, you will quickly get new decay. Dental decay occurs when bacteria in your mouth releases acid. The acid eats away at your teeth until you have a soft spot, then a hole, and then an infection or abscess.

It's important to control your diet because the more sugar you feed this bacteria, the more acid they can release. Eat healthy food at meals and avoid between meal snacks. The reason that hard candies and gum are so bad for your teeth is that they feed sugar to the bacteria for long periods of time.

Also, the longer the bacteria sit on your teeth, the more numerous and dangerous they become. If you aren't brushing and flossing properly, you leave this extra dangerous bacteria just sitting on your teeth waiting for their next sugar feeding frenzy. You feed them a little sugar and immediately they release acid that eats away at the teeth again. If you are doing a good job of keeping your teeth clean, you minimize the number of bacteria and reduce the amount of acid released.

There are two particular areas of your teeth that are more prone to decay. The first areas are the pits and fissures (grooves) on your back teeth. These areas can be very difficult to keep clean. However, once they are filled these fillings are small and can last a very long time. In children, we often place sealants (or plastic coatings) over these grooves to try to avoid decay before it starts.

The second weak spot for decay is between your teeth. If you don't floss you will eventually get decay in these areas unless you are one of those lucky few who are very resistant to decay.

To answer your question directly, there are a couple of reasons you might get new decay. The joint between the filling and your tooth is a weak spot just like the caulking material around your bathtub. As smooth as a dentist tries to make the joint, there is always a weak spot that starts to leak and break down. The bacteria find these weak spots and attack them with acid until they break down and decay again. If your diet and homecare are the same as before the fillings were placed, you will very likely get new decay.

Then why have the fillings done? The new silver, porcelain, or gold material will never decay and once the 'decay prone' areas have been filled you are less likely to get decay in the other areas of a tooth that are more resistant to decay. Finally, I know that you have 'seen the light' and your nutrition and oral hygiene are now perfect.

Q: My 6 year old child recently had her teeth cleaned. The dentist said that she has decay between some of her back teeth and needs fillings. Why do baby teeth need fillings if they are going to be replaced by permanent teeth? G.P. in Dover

A: Baby teeth have a number of reasons for being there. Among these reasons are the abilities to chew, eat, and facilitate speech. If you've ever been without one of your front teeth then you know how hard it is to speak properly. Additionally, your baby teeth act as space maintainers for your permanent teeth that are going to come in later. As we grow and get older, the baby teeth are replaced by permanent teeth that are generally bigger and stronger than the baby teeth that they replace.

In order for the baby teeth to act as space maintainers for the permanent teeth, they need to stay in until the permanent teeth are ready to replace them. Baby teeth are lost in two waves. The first wave usually starts around 6 years old and lasts 1 ? - 2 years. During this period, your child will lose his/her front 4 teeth (top and bottom) and get his/her first four permanent molars. For approximately the next 2 years nothing major happens, then the rest of the baby teeth start to loosen up and are lost over the next 2 years. You can see that the baby molars can easily be needed until your child is 10-11 years old. If the baby teeth are lost early, the spaces between teeth can close and the permanent teeth will come in very crooked. It can be much more difficult to straighten teeth with braces if many of the baby teeth were lost early.

I believe that it is very important for you to listen to your dentist and have the fillings done as soon as possible. When a small amount of decay is detected in a tooth it can be quick and relatively simple to fix. As the decay (hole) gets larger, the tooth becomes more difficult and costly to repair and save. If you wait too long it may become impossible to save a badly decayed tooth and you risk pain and infection.

Q: My 16 year old son just returned from the dentist. I was told that he has eight new areas of decay and needs six new fillings. I have been taking him for cleanings every six months and I don't understand why he has all these problems. Should I get a second opinion?

A: Second opinions are always OK, but let's see if your own expectations are realistic.

Six months is a short period of time to find lots of new decay, but decay is more difficult to find when it is between teeth. In its early stages, x-rays are needed to find interproximal (in between teeth) decay. Although it has been only 6 months since his last 'cleaning', I would imagine that it has been at least 1 year, and maybe more, since his last x-rays.

Tooth decay forms when there is an imbalance and an imbalance occurs when more bad things are happening to your teeth than good things. Certainly going to the dentist every six months is a good thing, but there are 363 other days in the year, and two cleaning appointments can't overcome weeks and months of neglect or bad habits.

Dr. Alan Goldfeder and I recently had a conversation regarding this very issue. We sort of decided that children don't brush or floss their teeth any better or worse than they did 20 years ago, but there seems to be an increase in decay in the teenagers that we are seeing. Without hard evidence we believe that bottled and filtered waters are reducing fluoride intake in youngsters and more sodas and fast foods are being consumed.

There are quite a few reasons for our perceived increase in decay: poor brushing and flossing habits, too many sweets in your diet, eating chewing gum or any other long lasting candies, and drinking too many carbonated drinks everyday (including diet). Carbonated beverages are particularly bad because the carbonation is acidic (carbonic acid) and will soften your teeth. Additionally, if there is inadequate daily fluoride consumption or a failure to have regular dental visits, the decay problem just gets worse.

Dr. Goldfeder and I have a list of recommendations that I believe are important. They are listed below:

These recommendations and the associated problems should help you evaluate your son and hopefully create better dental visits in the future.

Q: I had some fillings replaced a couple of weeks ago and the teeth have been very sensitive to cold. The sensitivity seems to be getting better but I'm not sure if I should be worried. E.P. in Montchanin

A: It is a good sign that the cold sensitivity is getting better. As long as you are getting a little better every couple of days I wouldn't worry. But if the sensitivity remains you need to have the fillings checked for fit and to make sure that you don't have the beginnings of a root canal problem.

Q: I am going to have my old silver fillings replaced. My dentist wants to replace them with a white filling material, but my old silver fillings never gave me any problems. Which material is better? G.Y. in Talleyville

A: I am happy to hear that you have had such good results with your silver fillings. It is a great material and has been used for many years. Unfortunately, as dentists, we see these silver fillings getting bigger and bigger over the years as they are replaced and redone. Eventually, the nerve in the tooth can die and you may need a root canal or the tooth can break and you may need a crown. I believe that the white (composite) fillings that your dentist recommended are a better choice. They have two properties that the silver fillings don't have. First, the white fillings bond, or stick, to the tooth. This helps to protect the nerve in the tooth and helps to keep the tooth from breaking if you bite too hard on it. The composite fillings actually strengthen the tooth. Secondly, patients have become much more aware and demanding about cosmetics and the way that they look. When composite fillings are placed, they are barely visible and it's a nice feeling seeing your teeth as though they have no fillings in them.

There are a couple of things you should know about white fillings. They are more difficult and time consuming for your dentist to place, so the cost is greater. Additionally, because the fillings are white, problems (such as decay) seem to show up better and sooner so they may not last as long.

To sum this up, there is no perfect material. From a durability standpoint, gold is the best filling material, but it is more costly than white fillings and not very cosmetic. The white cosmetic materials have a couple of drawbacks but I use them almost exclusively because I believe they are better than the old silver amalgam materials. It sounds like you have gotten good advice.

Q: Many of my old silver fillings need to be replaced. I want them replaced with white fillings and my dentist suggested onlays. The onlays are more expensive. What are they and why can't I just have fillings? H.B. in Pike Creek

A: Replacing your old silver fillings is probably a good idea. It is not uncommon for me to remove an old silver filling and find some decay under it, even if there is no decay evident on the x-rays. Old fillings of any type can begin to 'leak' much like the caulk around your bathtub. When the bathtub caulk is placed, it is smooth and white. Over time it starts to flake, stain, and mildew. When you remove it, you will find 'surprises' underneath. Old fillings also leak, stain, and conceal decay.

What you are really asking me is what choice of materials should you replace your old silver fillings with? To simplify this discussion lets break your choice down into three different materials; silver fillings, composite fillings, and onlays or partial crowns.

Silver fillings have been around for ages. They have stood the test of time, are relatively easy to place, and have been cost effective. But they have three drawbacks. First, they are ugly. Second, when they get to be medium to large in size, they can act as a wedge inside the tooth and lead to tooth fracture. Lastly, there is a growing concern about their mercury content. Although it is not considered a problem in the United States, the mercury content in new silver fillings is considered toxic in a number of European countries.

Composite or white fillings are slowly replacing silver fillings. Instead of being a wedge inside your tooth, composite fillings actually help hold your tooth together because they actually bond to the tooth's surfaces. In addition to helping to prevent fractures, they also help protect the nerve and reduce the need for root canals. But they have some drawbacks too. They are technically difficult and time consuming for the dentist to place. Additionally, as the white fillings get larger and larger, some problems begin to arise and it becomes more and more difficult to make them fit properly and keep them from breaking. At this point, it becomes time to consider doing onlays or partial crowns.

An onlay is a filling or partial crown made by a dental lab out of porcelain, composite, or a mix of both. When done properly, they are harder, stronger, prettier, and last longer than normal fillings. They are also more expensive and require two visits. More and more of these onlays, and their smaller cousins, the inlay, are being done. While, they are more costly and time consuming, they are the 'Cadillac' fillings of today.

In short, the onlays are probably your best option. You just need to balance the expense against the benefits. Your dentist should be able to help you with this.


Implants

Q: You recommend implants to replace missing teeth. Is this always the best choice? J.W. in Landenburg

A: Implants are terrific in many instances and the more experienced your dentist is with implants, the more likely you are to have a successful outcome from treatment. But, the time consuming surgical process is not for everyone. Bridges and partial dentures have been around much longer than implants and can give very satisfactory results. The choices usually start with checking the condition of the remaining teeth. If you have the right teeth in the right positions, and there is good bone support where the missing teeth are, then you can make choices based solely on economics. However, if time is limited and the arrangement of the teeth and bone are not ideal, then your choices may be limited.

Q: I am 38 years old. When I was about 12 years old I fell off my bicycle and cracked my upper front tooth. Since then that tooth has had a root canal, two metal posts, and two crowns. My dentist says that the tooth is cracked again and needs to be taken out. He said that he wants to place a bridge but I am not happy about drilling on the teeth next to the space. Do I have any other options to replace the missing tooth?

A: Although a number of options are available to you, I believe that an implant supported crown is your best choice. An implant is a titanium screw that is placed where your tooth root used to be. It is buried under the gums (into the bone) and over a few months, your bone will grow into the 'swiss cheese' holes in the implant. Once the implant is fixed or 'integrated' into the bone, your dentist can place a new crown over the implant. The implant has a number of advantages. First, you don't need to drill any other teeth. The implant supported tooth can support itself. Next, once a tooth is extracted, the bone that used to hold the tooth in place begins to melt away. Over the years this will create a 'hole' that may be difficult to hide with bridgework. Once the implant is placed, the bone will stop melting away. And finally, you will never get decay in your titanium implant.

The more visible an implant supported tooth is in your smile, the more important your choice of restorative dentist, oral surgeon, and dental lab becomes. Likewise, the more closely these three people have worked together, the more predictable your final result will be. Be sure to listen to your dentist's advice because there may be other factors to consider. For example, if there are large fillings on the teeth next to the space, a fixed bridge may still be your best choice. But remember, a properly placed implant can have a 95% success rate and last a long, long time.

Q: My 16 year old son had his top front tooth knocked out playing ice hockey. We read your column and we are thinking of replacing it with an implant. T.R. in Centerville

A: At 16 years old an implant should not be your first choice. An implant is a metal root that replaces a missing tooth. Once the implant has been secured (integrated) into the bone, a new tooth can be attached to it. While I don't know your son, it is a good bet that he is not finished growing. An implant should not be placed in a growing mouth. The target age for implants in girls is approximately 17-18 years old. The target age for boys is a couple of years older. Another reason to delay the placement of the implant is that normal teeth are all a little loose. When they get hit they can 'bend' a little instead of breaking. Implant supported teeth are very strong, but are more likely to break with a hard impact, like a hockey puck.

There are a number of good temporary tooth replacements, both fixed and removable, that your dentist can help you with until your son is old enough for an implant.


Root Canals

Q: My dentist said that I need a root canal. He wants to do it, but I thought specialists do root canals. Can you tell me what a root canal is and who should treat it? L.R. in Talleyville

A: Root canal therapy, or RCT for short, is most commonly done when the nerve inside the tooth is infected or sick. It can become sick for a number of reasons. There can be deep decay, large fillings, or simply a hard blow (trauma) to the tooth. Unlike ear infections and many other bacterial infections that you may have had, a sick nerve inside a tooth is not cured by medicine. An antibiotic may make the tooth feel better, but the pain and infection will return unless the nerve is removed.

During root canal therapy the nerve inside the tooth is removed and the tooth is 'hollowed out'. A common misconception is that the tooth's roots are removed. A more accurate analogy is a plumber cleaning out your pipes. The pipe still remains, but the 'sludge' on the inside has been removed. After the tooth has been 'hollowed out' using tiny little files, it is filled with a rubber material to prevent re-infection. When the root canal is complete you now have a tooth that is a weakened shell of its previous form. In most instances, especially on back teeth, it is important to place a crown on the tooth to strengthen it and prevent it from breaking. The good news is that root canals can be done with a very high degree of success and in most cases can be completed in a relatively short appointment with no discomfort.

Additionally, you are right, there are dental specialists that only do root canals. They are highly trained and can make even difficult root canals look easy. However, general dentists do most root canals. Any dentist with the proper training can perform root canal therapy and your dentist must feel comfortable with your particular situation or he would have referred you to an endodontist (root canal specialist).

Q: My dentist says that I need a crown on my back tooth that has had a root canal. Can you explain why? H.H. in Middletown

A: The answer is simple. A tooth that receives a root canal is 'hollowed out' and weakened. Additionally, a root canal problem is often caused by an already weakened tooth that may have had a very large filling or fracture. The combination of a tooth with large holes or fillings and hollow roots will often require the support of a crown to prevent a fracture that can cause you to ultimately lose your tooth.

Q: In the past, whenever I've had a root canal, I had a crown done also. I need a couple of new crowns, why don't I need to have root canals done first? L.W. in Greenville

A: Root canals and crowns are done for different, but sometimes related reasons. Just because you need one does not necessarily mean that you will need the other.

Teeth have tubes or 'canals' that run up the middle of their roots. Back teeth can have three or four of these tubes. These tubes contain a tooth's nerves. The nerves were needed when you were young and the tooth was forming, but as an adult with fully formed teeth, they are no longer needed. When the nerve becomes sick or infected from tooth decay, fracture, or other problems, it can be removed which, in turn, saves the tooth. Root canals are done for a number of different reasons, but the reason that most people understand or are familiar with is a tooth abscess.

Crowns restore the shape and strength of a decayed, broken, or discolored tooth. When a tooth has missing pieces from fracture or decay, a crown fills in the missing pieces. If a tooth has discolored from medications, large fillings, trauma, or age, a crown can restore the original tooth shade (or create an even better color).

Remember that a root canal is usually performed on teeth that have had a lot of decay or a bad fracture. These teeth are weak and probably scheduled for strengthening (crowns) even before the root canal is done. After the root canal has been finished, the tooth has been further weakened because it has been hollowed out in order to remove the sick or infected nerves. These weak teeth need to be restored with crowns. However, once in a while a nerve inside a tooth will get sick and/or die and the tooth has had no previous decay or fracture. In cases like this, when most of the tooth is intact, it is sometimes possible to avoid a crown.

Now let's turn this around. Suppose you have a crown done on a tooth that has never had a root canal. Does this tooth need a root canal now? Most teeth that need crowns never need a root canal, especially with the newer bonding materials that have been available to dentists over the last few years. Let's further suppose the reason you need a crown is because your tooth has a large filling with new decay. Your dentist is going to drill on the tooth, close to the nerve. If the previous filling was deep, then the nerve was probably slightly damaged. The tooth remembers every time it has been hurt from decay, fracture, and dentist drills. There is always the chance that a last bit of trauma to a tooth can make the nerve so sick that it won't get better on its own and a root canal may be necessary. In other words, it's possible that doing a crown may irritate the tooth and cause a root canal, but the odds are in your favor that a root canal won't need to be done.

Q: My 40-year-old daughter has been seeing a dentist in another state. Even though she has had excellent dental care from the time she was a child she has needed 3 root canals over the past year. Her dentist was highly recommended and has a great reputation but we are losing confidence. Why has she needed all these root canals? R.B. in Wilmington

A: Without seeing your daughter I'm going to do a lot of guessing, but I think that I can help. A root canal is done to treat a sick and dying nerve. So what you are really asking is, 'why are the nerves on your daughter's teeth sick and dying now?'

The nerves inside of teeth only have a very small ability to heal themselves and the nerves seem to remember everything that has ever happened to them. For instance, the time that you bit into a hamburger and hit a piece of bone, or the time you fell off your bicycle and hit your front teeth, or all the years you have been grinding your teeth at night, have all hurt your teeth. However, the worst things that happen to your teeth are usually associated with going to the dentist. Dentists drill on your teeth to remove decay, fix broken pieces, or even place crowns. The deeper the decay or fracture, the closer the drill gets to the nerve, and the greater the chance of creating nerve sensitivity or even a dying nerve (or root canal problem).

When you are young, the blood supply to the tooth is very strong and teeth seem to bounce back from problems pretty well. As you get older, this blood supply diminishes and increases the chance that a sick nerve will die.

As you can see, age alone can increase your chances of needing a root canal. When you add all the other problems your teeth may have had, you increase the root canal risk even more.

Over the last few years dentistry has been exploding with new materials and techniques. When used properly, these new materials are strong, beautiful, and comfortable, but they are very technique sensitive to use. If your daughter's dentist has not quite mastered these materials, he could have helped introduce these sensitivity problems on some of her teeth. However, simply replacing those sensitive fillings usually solves the sensitivity problem and avoids a root canal.

My last concern is what appears to be a lack of confidence that you have for your daughter's dentist despite his reputation. I believe that a second opinion is called for. A second opinion may be the best way to find out that your daughter has had excellent dental work done and re-establish her confidence.

Your daughter's dentist has a great reputation because he cares about his patients and the work that he does. It can't hurt to have an open discussion with him.

Q: About three weeks ago I had a root canal done on a back tooth. The tooth still hurts when I chew on it. Shouldn't it be feeling better by now? What do you think is going on? G.Y. in Wilmington

A: I can't diagnose your problem without seeing you but I can give you some general ideas. First, a root canal is a treatment that removes a sick or dead nerve from inside a tooth. The root of the tooth is not cut off, it is hollowed out. For a dentist, a root canal is like doing a tiny little puzzle, under water, in the dark (you know, fun). But, like any other procedure, not all root canal treatments are successful. While 97% of our treatments work, there can still be complications.

Let's get back to your problem. If you are still in pain, then the area is still infected, still inflamed, or there is a second undiagnosed (or missed) problem.

If the tooth is still infected it may need to be retreated. A tooth can have more than one nerve and a nerve might have been hidden and missed. We are trained to look for these hidden nerves, but some can be almost impossible to find. Sometimes a root is not completely cleaned out and some residual infection is left. Redoing that root can solve the problem. Other roots may be completely inaccessible and can lead to lingering problems.

Even a properly treated root canal tooth can be painful. I have found that the longer a tooth hurts or is uncomfortable, the longer it seems to take to heal. Complete healing can take weeks or longer if the infection was very bad. Sometimes if the tooth has an improper bite (or occlusion), a simple 'bite' adjustment can solve your problem.

You must also keep in mind other possible problems. I have seen a second tooth, next to the first one, also need a root canal. Your dentist must look for cracked roots and infected gums. Is the tooth near an infected sinus or do you grind your teeth at night? TMJ or muscle pain can sometimes feel like a toothache.

I hope this helps. A return visit to your dentist should help to diagnose and solve the problem.