A dentist may use any of several different types of direct restorations (fillings) to restore decayed teeth. Each material has its own set of characteristics, so different situations call for different procedures.
Silver amalgam remains the most durable and cost-effective method of restoring small to medium sized cavities on load-bearing surfaces of back teeth, where appearance is not a concern. It consists of silver, mercury,and several other metals chemically bonded together in an alloy which provides thermal expansion and other characteristics similar to that of natural tooth structure. This material has been used successfully for over a century, and its safety and effectiveness has been studied more than any other direct restorative (filling) material.
Contrary to misleading claims you might have seen in pseudo-science tabloids, the mercury in silver fillings does NOT cause systemic diseases such as multiple sclerosis and cancer. Replacing fillings for the purpose of curing such illnesses is costly, unnecessary, and potentially damaging to the teeth. Moreover, silver fillings do not "leak" toxic mercury to any significant degree. Just as the individually harmful elements of sodium and chlorine are chemically joined to form the harmless substance table salt, and those elements do not "leak" out of the salt, silver amalgam does not "leak" mercury. The American Dental Association's website is a good source of scientifically valid information regarding amalgam. Enough of that... let's move on.
OK, so silver amalgam restorations are economical, durable, and biologically compatible with teeth. However, they are made of metal so they don't look like tooth structure, and wouldn't look good on front teeth. Fortunately, the front teeth are not subjected to biting forces which are as heavy as those imparted to the back teeth. So a dentist can use any of several plastic type materials which can closely match the color of the tooth, even though they do not hold up as well as silver amalgam under heavy biting loads. These tooth colored filling materials include composite resin, glass ionomers, and resin ionomers. Your dentist can choose which material to use in any given situation based on the characteristics of each individual material.
Direct restorations are the economical and tooth-kind way of restoring small to medium size cavities. However, when a tooth is damaged so badly by decay or injury that little or no tooth structure is available to hold a direct restoration in place, then a crown can be a feasible alternative. A crown wraps around a damaged tooth to strengthen it as it restores its original contours.
By the time a tooth has been damaged badly enough that it requires a crown, it typically requires a buildup procedure prior to preparation for a crown. This is basically a very large direct restoration, reinforced with threaded pins or adhesive retention, which acts as a foundation to support the crown. The buildup and any remaining tooth structure are then reduced to the shape of a somewhat complex cylinder. Your dentist will then take an impression of your prepared tooth, and make a temporary crown to protect the prepared tooth until your long term crown is made.
Crowns can be made of a gold alloy, porcelain fused to a gold platinum paladium coping, or castable porcelain. The combination of metals mimics thermal expansion and other characteristics of natural tooth structure. The choice of crown type depends basically on the strength required, which favors gold alloy, and esthetics, which favors porcelain. Generally a gold crown is the most durable restoration available:
If decay or traumatic injury damages the tooth pulp, which consists of nerve tissue, blood vessel, and artery, those tissues become inflamed. If the damage is slight, the inflammation will subside after repair of the damaged tooth and no further treatment may be required. However, if the damage is more severe the pulp tissue may not heal and will eventually die. The resulting breakdown products will leak out through a natural opening in the root tip and cause an abscess which destroys the surrounding bone. In such a case the only options that will relieve the abscess are the removal of the tooth, and root canal therapy.
Root canal therpay involves the removal of the necrotic pulp material through an opening made in the biting surface of the tooth. The canals within the root are then reshaped and filled, generally with a material called gutta percha. A buildup and crown are often made to strengthen the tooth, since the tooth loses its hydration supply when the pulp dies, and it becomes somewhat brittle and prone to fracture.
This process works well about 95% of the time. However, occasionally root canal therapy does not resolve the abscess and the tooth cannot be saved.
If a tooth is lost and not replaced, a loss of chewing efficiency is only one of several possible consequences. The tooth behind the resulting space often drifts slowly forward, and the tooth opposing the missing tooth often drifts up or down into the space. This drifting adversely changes the bony support of those teeth, which can ultimately result in their loss too. Sort of a domino effect...
Your dentist may suggest any of several options to replace a missing tooth, depending on the dental situtation. If a tooth is present of each side of the space, a bridge might be used. The teeth on either side of the missing tooth are prepared for crowns, an impression is taken, and the teeth are protected with temporary crowns. A bridge is made in the laboratory which consists of crowns for each prepared tooth, fused to a false tooth croown to replace the missing tooth:
Another way to replace a missing tooth is with an implant retained crown. An implant is an artificial tooth root, typically made of titanium, which is surgically inserted into the bone in the area of the missing tooth. After a period of healing, a crown is constructed and attached to the top of the implant, providing the replacement for the missing tooth.
Up until a few years ago, implants were considered somewhat unreliable. Now, as techniques and materials have dramatically improved, it is a predictable and viable alternative to a bridge, so long as such considerations as bone support and bite are favorable.
An implant offers several advantages over a bridge. The teeth either side of the space do not have to be cut down for crowns. An implant retained crown is easier to keep clean, since it can be flossed like any other tooth. Floss threaders are not needed to clean beneath a false tooth as is the case with a bridge.
Implants can also be used to provide supplemental retention for dentures:
When many or all teeth are missing, fixed appliances such as bridges may not be feasible due to dental or cost considerations. A partial denture can replace several missing teeth with one removable appliance. The partial denture is kept in place by friction against parallel walls prepared in key tooth surfaces, and by clasps which engage undercut areas in other tooth walls. The appliance is removed after meals for cleaning, and is generally kept out of the mouth at night. Partial dentures represent a somewhat simpler and more economical way of replacing several missing teeth:
When all upper or lower teeth have been lost, a full denture is often used. An upper full denture is retained with suction against the palate, while a lower full denture is retained primarily by muscle action of the cheeks and tongue. It also is removed after meals for cleaning, and kept out at night:
When plaque and tartar are allowed to remain on root surfaces due to inadequate cleaning, bad things usually happen. Due to the relative softness of root structure, decay can form there easier than it can on other tooth surfaces. Another problem is more prevalent in adults, however. The byproducts of bacteria in plaque can cause gum inflammation, which manifests as swollen bleeding gums. This in itself is generally reversible. However, as those toxic byproducts continued to be secreted by bacteria, the bone supporting the tooth roots is slowly destroyed. This process is generally NOT reversible, and once bone has been lost it is gone for good.
Treatment often consists of 3 or 4 steps. The first is removal of the immediate source of the inflammation (plaque and tartar) by a procedure called scaling and root planing, or curettage. Second is changes in daily oral hygiene technique so plaque removal is more effective at home. Third is a program of dental cleanings every few months or so. The fourth step is sometimes needed, depending on response to the first 3. That is surgical recontouring of areas where remaining bony defects impede the ability to keep the tooth roots clean at home.
If this doesn't sound fun, see prevention.
Malposed teeth and discrepancies in tooth and jaw size present not only esthetic problems, but also functional ones. Poorly positioned teeth can cause difficulty cleaning, increasing chances of gum diseases problems. An improper bite relationship can cause unhealthy pressure in the jaw joints, contributing to temporomandibular joint disorder (TMD)
Sometimes an orthodontist can plan shorter and more effective treatment if he or she can see a child before the primary, or baby, teeth have been lost. The orthodontist may be able to take advantage of growth spurts, for example, to guide jaw growth in a more favorable direction.
If a discrepancy exists between tooth size and jaw size, there may not be enough room for wisdom teeth, or third molars. If that is the case, the wisdom teeth could remain "impacted" behind the second molars. Leaving impacted wisdom teeth in place could result in damage to the jaw bone, infections of the overlying gum tissue, and resorbtion of roots of the teeth in front of the impacted wisdom teeth. A dentist can generally tell whether space exists for wisdom teeth by the mid to late teenage years.
As soon as this problem becomes evident, your dentist may suggest having the teeth removed. The healing process is at a peak during teenage years, so that is often an ideal age for removal. Generally speaking, whatever discomfort a person experiences following the extraction of one third molar is pretty much the same as after the extraction of 4 third molars, so it usually makes sense to have all 4 removed at the same time. That way the procedure must be experienced only once.
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