Basic Dental Summary, Tooth Anatomy, and Physiology

Enamel is a very hard covering of the top of the tooth designed to aid in chewing food and last for a long time even when repetitive erosive forces of chewing food act upon it. It is made of an organic and inorganic matrix. This means it has a scaffold of protein fibers that have been mineralized. These minerals come on and off the tooth in microscopic amounts throughout the day and are in equilibrium. Bacteria produce acids and promote demineralization and saliva has minerals in it that promote mineralization. Imbalance in this equilibrium can cause the tooth to become more and more demineralized and create caries also known as a cavity. If the demineralization has not passed the enamel layer, and the inorganic matrix is still intact, the tooth may be able to still remineralize naturally and a filling may not be needed. If the cavity has passed the enamel layer or the inorganic matrix is destroyed, a filling will need to be done. Under the enamel lays a softer layer of dentin that is designed to disperse shockwave forces produced from chewing in a way that allows the tooth to resist microfracture damage over time. This dentin layer cannot resist bacterial erosion nearly as well as enamel and can be destroyed a lot quicker when bacteria reach it. Fillings are designed to act as prosthetic enamel and dentin to fill areas that have been destroyed from caries or fracture. These replacement tooth materials are fake and not as good as natural healthy enamel and dentin but serve as a decent replacement when the natural dentin and enamel have been destroyed or compromised. 

The top visible portion of the tooth is called the crown. When the majority of the crown is filling material or important parts of the tooth that provide structural integrity have been destroyed, a prosthetic crown will be recommended. For this procedure, the enamel layer or what would have been enamel layer is removed and a prosthetic or fake enamel layer is placed. These prosthetic crowns are fabricated as one unit to give strength back to the visible portion of the tooth. All gold crowns provide the best functioning restorations in that they act the most like natural enamel and have the best seal but look like metal. All- ceramic crowns look the best but anything with ceramic can break if overloaded with force. Porcelain fused to metal crowns are crowns that are hybrids of the other two attempting to get the best of both. They can have excellent metal seals and some porcelain coverage in the visible areas but are not always recommended and, as they contain porcelain, they can break. Onlays and inlays are basically partial coverage restorations similar to crowns and try to provide more structural stability in the tooth in situations where a crown is not quite needed but a filling is not strong enough. 

The root of the tooth is composed of dentin with a small layer of a similar substance called cementum. The root is connected to the bone via thousands of tiny ligaments. These ligaments act like trampoline springs and help the tooth have some give as it resists chewing forces. This joint between the tooth and bone is called the periodontal ligament. When fills are too high or someone bites on one tooth too hard these ligaments can get bruised just like any other joint. This can cause severe pain and will go away if the problem is resolved (if from a fill that is too high the fill must be adjusted) and the bruise is allowed to heal. Plaque is a biofilm. In other words, it is a form of glue that bacteria use to form a colony on teeth. When we brush, our goal is to remove this biofilm. Flossing is effectively brushing between the teeth where the brush bristles cannot reach. If the plaque is left in the mouth for some time it will take up the minerals in the saliva and harden into tarter also called calculus. This can only be removed with hygiene tools at the dental office. If not removed it serves as an even easier substrate for more colonies of bacteria to adhere to. Chronic plaque on the teeth allows for bacteria to release acid that causes cavities right onto the tooth surface and the other byproducts of bacteria irritate the gums just as your skin becomes irritated when bacteria colonize on it. The immune system then tries to fight the bacteria by causing inflammation called gingivitis. As the bacteria are on the surface of the gums and not within it, however, the body is unable to rid itself of these bacterial colonies on its own. Thus the inflammation continues and intensifies until it starts to cause damage to itself and the connection of the gums to the tooth as well as the periodontal ligament become damaged. Little by little these connections can be lost and the tooth becomes less and less supported. This is called periodontal disease and can lead to tooth loss. The only way to stop this process is to go in for regular recommended cleanings. If the gums also known as the gingiva  have lost connection and are forming deep pockets next to the tooth, other more harmful types of bacteria begin to invade these areas and deep cleanings known as scaling and root planing will need to be done to rid the area of this bacteria and allow the pockets to heal up. If the deep pockets are not found a normal cleaning may be able to be performed called a prophylactic cleaning. Scaling in the presence of gingivitis is a procedure where a lot of tartar must be removed in a situation without deep pockets. Periodontal maintenance is done when scaling and root planning have helped to stabilize compromised gingiva and is the type of cleaning to maintain the tooth supporting tissue from losing more connection. 

Sometimes bacteria invade close or into the pulpal tissue. The pulpal tissue is the nerve and blood vessels in the center of the tooth in the canal. The bottom part of the root is known as the apex. The opening of the canal at the apex to the bone where the blood vessels and nerve run is very narrow. If the pulpal tissue gets inflamed too much and swells it cuts off its own circulation and gangrenes or dies. This allows bacteria to colonize the pulp and spill out into the bone causing abscess and bone destruction. When fillings get close to or barely touch the pulpal tissue a pulp cap can be done. This is a medicated material designed to kill bacteria and be biocompatible to allow the pulp to calm down and survive. It is not always effective but could save the patient from needing a root canal if the pulp does not die. Instances where the pulp is dying and cannot be stopped are called irreversible pulpitis. This is very painful and can only be completely relived with root canal therapy. Instances where the pulpal tissue has died are called pulpal necrosis.  Both of these need root canal therapy. Root canal therapy is a procedure where all the dying or dead pulpal tissue is removed and a filling that reaches the end of the root to fill the canal space is done. Not all teeth have straight forward canal systems. Some can branch off and have extra canals that go out the side of the root. Some of these variations can be recognized during treatment and the patient can be sent to a specialist sometimes it cannot be seen in radiographs or during treatment. This can cause a root canal to fail and have to be redone. Not all teeth can be saved with root canal therapy even with the specialist. The specialist will have other options such as apicoectomy where they do a small surgery to fill the apex opening from the bottom of the tooth. 

Patients many times due to one or more reasons lose teeth. Replacing these teeth is important as the remaining teeth will be taking more pressure than they are designed to take and could break. The more teeth you lose the worse this problem becomes. The best option is implants. An implant is a prosthetic root that the dentist can place a crown, bridge or denture attachment to. It is made of titanium and will be placed in the bone and allowed to heal in a way that the bone attaches to it and supports it. The implant prostheses cannot get cavities but they can get bone loss with periodontitis like reactions if they are not kept clean. Patients will sometimes need bone grafts if the area does not have enough existing bone. This is when artificial, animal or cadaver bone is surgically placed in the site of a bone defect or extraction in order to facilitate healing in such a manner that the bone is augmented in order to place an implant. Implants are sometimes immediately loaded with a temporary crown or the gums are stitched over them to allow for more healing into the bone before doing a temporary. Implants can be used as an anchor for bridges or crowns. Sometimes a partial or full denture will be held in place with some snaps called locators. This allows for more stability with the added ability to remove the denture when needed to clean it well. Bridges can also be done to fill spaces. If the space is not too big, crowns can be done on the teeth next to the space and a false tooth can be attached to them. A bridge is fixed and not removable. One must keep the area under the fake tooth called a pontic clean with floss. Stiff ended floss is a great way to do this.  Partial dentures fill spaces in the upper or lower jaw and have metallic hooks that grab onto remaining teeth to get some retention. Full dentures can be fixed to implants or can exist on their own. Without help from implants they generally do slosh around a bit when using them. Upper ones are usually more tolerable but lowers tend to move a lot and one must practice holding it in place by scrunching the lower lip muscles. Denture adhesives can help them be more stable. Upper dentures can cause speech changes. I always tell patients that dentures are akin to crutches. Crutches are an aid to help people get around but are uncomfortable and nothing like walking. The same is true for dentures. They are big pieces of plastic that are uncomfortable pretending to be teeth and helping you get by. Chewing is not the same as when you had teeth. You have to try to balance the food and only use the back teeth as the function of dentures usually makes front teeth only useful for looks. Dentures may be right for your mouth and financial situation, however, implants are always recommended.